design of pilot plant based on new blasting explosives

Design of Pilot Plant based on New Blasting

Explosives Developed from Decanted

Trinitrotoluene (TNT)

By

MUHAMMAD FAROOQ AHMAD

School of Chemical and Materials Engineering (SCME)

National University of Sciences and Technology (NUST)

2018

Design of Pilot Plant based on New Blasting

Explosives Developed from Decanted

Trinitrotoluene (TNT)

Author: MUHAMMAD FAROOQ AHMAD

Registration No: 2011-NUST-TfrPhD-EM-E-90

This thesis is submitted as a partial fulfillment of the requirements for

the degree of doctor of philosophy

PhD in Energetic Materials Engineering

Supervisor Name: Dr. Arshad Hussain

Co- Supervisor: Dr. Abdul Qadeer Malik

School of Chemical and Materials Engineering (SCME)

National University of Sciences and Technology (NUST)

H-12 Islamabad, Pakistan

September, 2018

Dedication

To

My Beloved Parents

(Whose untiring efforts have made me achieve this milestone)

Loving Wife, Caring Siblings & Pretty Daughter

(Who always stood with me, encouraged and

helped me in achieving my goals)

Pakistan Army

Respected Teachers

Trustworthy Friends

Time Tested Colleagues &

Shuhada e Pakistan

Acknowledgments

All praise is due to Almighty Allah (S.W.T.), the ultimately, the

most Merciful and the Most Beneficent who gave me potential for

completion of my research work. All the respect to Our Holy

Prophet Hazrat Muhammad (P.B.U.H) who assisted us in

recognition of our Creator

I would like to express my most sincere gratitude to my supervisor

Dr. Arshad Hussain. His endless support and assistance coupled with his

tolerance, sound knowledge and perseverance made my research goals

attainable. I shall never forget his gentle attitude, supervision, and kind

concerns. My thanks are also due to my co-supervisor Dr. Abdul Qadeer

Malik for his benign guidance and everlasting support. Without supervision

of Dr. Abdul Qadeer Malik, I think my goals were never going to be

fulfilled. His words of advice in the crucial times of my research work

always paid me a lot for which I am really obliged to Dr. Abdul Qadeer

Malik. Besides my supervisors, I would like to acknowledge my GEC

members not only for their insightful comments and encouragement, but

also for the hard questions which incited me to widen my research from

various perspectives. Worthy members of the GEC include Dr. Habib Nasir,

Dr. Iftikhar Ahmed Salarzai and Dr. Nazr e Haider (ex Director

D.E.S.T.O).

I would also like to say thanks to Pakistan Army Ordnance Corps in

general and Brigadier Zulfiqar Sadiq in particular for sparing me to

complete my PhD at National University of Sciences and Technology

(NUST). With this, my appreciation also goes to School of Chemical and

Materials Engineering (SCME), NUST for providing me with an

opportunity and sufficient funds to complete my research work.

I would like to express my thanks to my friends Mr.Jawwad Akbar,

Mr. Abu Bakr, Mr. Imran Ali Shah, Dr. Rizwan, Dr. Adil Shah, Mr. Amir

Mukhtar, Dr. Muhammad Ahsan, Mr. Nawaid Ahmad for helping me

throughout these years with their moral support and extreme help whenever I

was feeling discouraged and frustrated. I am extremely thankful to entire

SCME staff for their consistent help and support in every possible manner. I

also applaud the nice company of my class fellows i.e. Dr. Zaheer ud Din

Babar, Mr. Muddassar Ahmad, Mr. Syed Sajid Ali Shah, Dr. Mukhtar

Ahmad Gondal, Mr. Azizullah Khan and Mr. Sajid Nawaz Malik. I always

cherish the happy moments spent with them.

I would love to recognize the sacrifices of “Shuhada e Pakistan”

who are our “Real Heroes” as they shed their blood and lose their lives

while defending our motherland.

I pay my homage and sweet sensation of love and respect to my

family including my parents, my siblings, my wife, my sweet daughter and

my close relatives who prayed for me all the time and helped me in every

possible manner. It would not have been easy to complete this work without

their cooperation and prayers.

Thanks a bunch!

(Muhammad Farooq Ahmed)

Abstract

This work presented in the thesis pertains to the design of a pilot plant based on

new blasting explosives developed from decanted Trinitrotoluene (TNT). Disposal of

life-expired and unwanted munitions is a great challenge across the globe. In the past,

these unserviceable explosives were disposed of through conventional disposal

techniques such as Open Burning/ Open Detonation (OB/OD), sea dumping,

underground demolition, incineration and biological degradation. Production of

poisonous and toxic gases such as NOx, COx, etc. during these disposal techniques have

always been a great concern for Environmental Protection Agency (EPA). Besides,

labour cost for the preparation of disposal pits, fuel requirement for shifting of explosives

to munition disposal sites and use of large quantities of serviceable explosives during

disposal of these unwanted munitions makes these techniques most uneconomical, unsafe

and unfriendly for the environment.

In order to curtail all these practices, decanting of explosives through decanting

plant were carried out for different munitions. All decanted explosives, particularly

decanted TNT, were disposed of further through open air burning. In the present research

work, efforts have been made to reutilize the decanted TNT. For this purpose, various

ingredients such as oxidizers, stabilizers and additional fuels have been added to the

decanted TNT to convert it into viable blasting explosive compositions. Laboratory scale

experiments using decanted TNT and other ingredients such as calcium ammonium

nitrate (CaAN), commercial grade wax and calcium carbonate (CaCO3) have been

carried out to make different blasting compositions. All the newly formulated

compositions were characterized through different analytical techniques such as

Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Thermogravimetry/

Differential Thermal Analysis (TG/DTA) and Fourier Transform Infrared (FTIR) to

study their morphological and thermal cum kinetic properties. Simultaneously, Horowitz

and Metzger method is used for calculation of activation energy (Ea) and enthalpy of

different samples. Once all compositions were certified for their future use, velocities of

detonation (VOD) measurements were conducted. Besides, stability tests, the density of

all these compositions were also measured.

In order to translate the laboratory scale compositions into useable blasting

explosives, a pilot scale plant has been designed using PTC-Creo Parametric 3D

modeling software. Similarly, simulation of the design was carried out through Aspen

Plus® V8.4 simulation software. Based on the successful simulation and design results, a

state-of-the-art, safe, feasible and environment friendly semi-automatic pilot scale plant

has been fabricated and installed for the conversion of decanted explosive into blasting

explosives for civil and military applications. Main components of the plant include

double jacketed mixing drums, brass-made mashing roller, 5 Horse Power (HP) motor,

vertical gear box and fume discharging unit having explosives production capacity of

about 10kg/ hour per batch. All the safety parameters required during manufacture,

filling and formulation of explosives have been ensured to avoid any untoward situation.

Functional test of this plant was performed using dummy explosive materials having

almost similar compositions. Subsequently, blasting explosive samples were produced

utilizing decanted TNT and other suitable ingredients. To ascertain their performance,

VOD tests of all newly formulated blasting explosives have been performed. It is worth

mentioning that the resultant VOD of all the samples fall between 2600-4400 m/s which

makes it the most suitable product for use in blasting applications such as mining,

quarrying, underwater blasting, etc.

In a nutshell, the present research work not only provides an opportunity for risk-

free reutilization of decanted TNT where new products are easily manufactured, cheap in

cost and safe in handling; but EPA concerns regarding emissions of toxic gases into the

atmosphere are also amicably addressed through reutilization of unwanted TNT that will

ultimately enhance Carbon Credit Ratings of Pakistan around the globe.

i

List of Contents

Chapter No. 1: General Introduction

1.1 Energetic Materials 1

1.2 Constituents of Explosives 2

1.2.1 High Explosives 3

1.2.2 Low Explosives 4

1.2.3 Distinction between Propellants, Explosives and Pyrotechnics 4

1.3 Types of Explosions 4

1.4 Deflagration (Fast Combustion) 5

1.5 Detonation (Supersonic Combustion) 5

1.6 Chemical Composition and Behaviour of Explosives 6

1.6.1 Explosive Mixtures 6

1.6.2 Explosive Compounds 7

1.7 Applications of Explosives 7

1.8 Military High Explosives 8

1.8.1 Physical Properties of Military High Explosives 9

1.8.2 Broad Categories of Military High Explosives 10

1.8.2.1 Primary High Explosives 10

1.8.2.2 Booster or Intermediary Charges 11

ii

1.8.2.3 Secondary High Explosives 11

1.9 Commercial Explosives 13

1.9.1 Blasting Caps (Detonators) 13

1.9.2 Safety Fuse 15

1.9.3 Detonating Cord 16

1.9.4 Explosive Boosters 17

1.9.5 Dynamite 18

1.10 Environmental Impact 18

1.11 Demilitarization 18

1.11.1 Dominating Features for Disposal of Unwanted Munitions 19

1.11.2 Environmental Hazards 19

1.11.3 Economic Effects 20

1.11.4 Safety Concerns 20

1.11.5 Obsolete or Outdated Munitions 20

1.11.6 Steps involved in Demilitarization 21

1.11.6.1 Transportation of Unwanted Munitions 21

1.11.6.2 Unpacking and Disassembly 21

1.11.6.3 Removal of Explosives 23

1.11.6.4 Open Burning/ Open Detonation (OB/OD) 23

1.11.6.5 Resource, Recovery and Reutilization (R3) 25

iii

1.11.7 Dumping 26

1.11.8 Sea Dumping 26

1.11.9 Demolition 27

1.11.10 Explosive Train 28

1.12 Environmental Protection Agency (EPA) and Pak-EPA 29

1.13 Motivation for the Present Research Work 30

1.14 Scope of the Present Research Work 31

References 36

Chapter No. 2: Experimental Techniques, Materials and

Methods

2.1 Purpose of the Present Research Work 37

2.2 Experimental Techniques 37

2.3 Thermal Analysis 37

2.3.1 Thermal Analysis Methods 38

2.3.1.1 Differential Thermal Analysis (DTA) 38

2.3.1.2 Thermogravimetery (TG) 39

2.3.1.3 Differential Scanning Calorimetry (DSC) 39

2.3.1.4 Thermo Mechanical Analysis (TMA) 39

2.3.1.5 Dynamic Mechanical Analysis (DMA) 39

http://en.wikipedia.org/wiki/Differential_thermal_analysis

iv

2.3.1.6 Thermo-magnetometry (TM) 39

2.3.1.7 Emanation Thermal Analysis (ETA) 39

2.3.2 Differential Thermal Analysis (DTA) 39

2.3.2.1 Sample Related Factors 41

2.3.2.2 Instrument Related Factors 41

2.3.3 Thermogravimetry (TG) 42

2.3.3.1 Working Principal of TG 43

2.4 X-ray diffraction (XRD) 44

2.5 Scanning Electron Microscopy (SEM) 46

2.6 Velocity of Detonation (VOD) Measurement 47

2.7 Fourier Transform Infrared (FTIR) Spectroscopy 49

2.8 Materials Used 50

2.8.1 Oxidizers 50

2.8.2 Fuels 50

2.8.2.1 Recovered/ Decanted TNT 50

2.8.2.2 Aluminium (Al) Powder 51

2.8.2.3 Saw Dust 52

2.8.3 Paraffin Wax 53

2.8.4 Calcium Carbonate (CaCO3) 53

v

2.9 Compositions of Newly Formulated Blasting Explosives 53

2.9.1 Compositions Formulated at Laboratory Scale 54

2.9.1.1 Composition No.1 with TNT and 15% Al (TAL-1) 54

2.9.1.2 Composition No.2 with TNT and

26% Al Powder (TAL-2) 54

2.9.1.3 Composition No. 3 (TAN) 55

2.9.1.4 Composition No. 4 (TCAN) 55

2.9.1.5 Composition No. 5 (TACAN-1) 56

2.9.1.6 Composition No. 6 (TACAN-2) 56

2.9.2 Compositions Formulated through Pilot Plant 57

2.9.2.1 Composition No. 7 (TCAN-1) 57






2.10 Kinetic Evaluation Methods 59

2.10.1 Significance of Kinetic Evaluation for Explosives 59

2.10.2 Horowitz and Metzger Method 60

References 62

vi

Chapter No. 3: Morphological and Thermal cum Kinetic

Studies of Assorted Explosives

3.1 Summary of the Present Research Work 64

3.2 Experimental Conditions 65

3.2.1 Arrangement of Explosives 65

3.2.2 Recovery of TNT and RDX from US Comp B Explosive 65

3.2.3 Analytical Techniques 67

3.2.3.1 Scanning Electron Microscopy (SEM) Analysis 67

3.2.3.2 Thermo gravimetric/ Differential Thermal Analysis

(TG/DTA) 67

3.2.3.3 X-ray Diffraction (XRD) Analysis 68

3.2.3.4 Fourier Transform Infrared (FTIR) Spectroscopy 68

3.3 Results and Discussion 68

3.3.1 Scanning Electron Microscopy (SEM) Analysis 69

3.3.1.1 US Composition B 69

3.3.1.2 Recovered TNT 70

3.3.1.3 Original TNT 72

3.3.1.4 Recovered RDX 74

3.3.1.5 Original RDX 75

vii

3.3.2 Thermogravimetric (TG) Analysis 77


3.3.4 X-ray Diffraction (XRD) Analysis 79

3.3.5 Fourier Transform Infrared (FTIR) Spectroscopy 80

3.4 Conclusion 83

References 84

Chapter No. 4: Comparative Analysis of Decanted TNT

Vis-à-vis Serviceable TNT for Reutilization as Blasting

Explosive



4.2.1 Decanting of TNT from Unserviceable Munitions 86

4.2.2 Equipment of Decanting Plant 87

4.2.3 Arrangement of TNT Samples 88

4.3 Analytical Techniques 88

4.3.1 SEM Analysis 88

4.3.2 TG/DTA 88

4.3.3 XRD Analysis 89

4.4 Kinetic Evaluation Methods 89

viii



4.5.1.1 Decanted TNT Unsvc 89

4.5.1.2 TNT Svc 91



4.5.4 Horowitz and Metzger Method 94


4.6 Conclusion 98

References 99

Chapter No. 5: Formulation of New Blasting Explosives

Developed from Decanted TNT and Aluminium Powder


5.2 Formulation of New Blasting Explosives Developed from

Decanted TNT and Al Powder 101


5.3.1 Formulations Process 101

5.3.2 Percentages of Ingredients used during Experiments with Al Powder 103

5.3.3 Characterization of Serviceable and Unserviceable Explosives 104

ix



5.4.1.1 Chinese TNT Svc 105

5.4.1.2 Decanted TNT Unsvc 107

5.4.1.3 TNT / 15%Al Sample 109

5.4.1.4 TNT / 26%Al Sample 111




5.5 Conclusion 118

References ` 119

Chapter No. 6: Formulation of New Blasting Explosives

Developed from Decanted TNT and Suitable Ingredients


6.2 Laboratory Scale Formulations of Blasting Explosives 122

6.2.1 Materials Selection 122

6.2.2 Procedure Adopted during Laboratory Scale Experiments 123

6.2.3 Special Precautions Kept in Mind During Experiments 124

6.2.4 Abel Heat Test of Laboratory Formulated Blasting Explosive Samples 125

x

6.2.5 Procedure Adopted for VOD Measurements 126

6.2.6 Field Tests of Laboratory Formulated Blasting Explosives

using VOD Meter 128

6.2.7 Density (g/cc) Calculation of Laboratory Formulated

Blasting Explosives Samples 130

6.3 Formulations of New Blasting Explosives though Pilot Plant

and Their Field Tests 131

6.3.1 Materials Selection 131

6.3.2 Procedure Adopted During Real Time Experiments 132

6.3.3 Stability Tests of New Blasting Explosive Formulated through

Pilot Plant 133

6.3.4 VOD Measurements of New Blasting Explosive Formulated

through Pilot Plant 134

6.3.5 Density (g/cc) Calculation of New Blasting Explosive Formulated


6.4 Conclusion 138

Reference 138

Chapter No. 7: Pilot Plant Design, Simulation and

3D Modeling

7.1 Summary of the Present Research 139

7.2 Process Flow Diagram (PFD) of Pilot Plant 140

xi

7.2.1 Aspen PLUS® V8.4 Simulation Software 140

7.2.2 Steps involved During Simulation Process 141

7.2.2.1 Components Selection 142

7.2.2.2 Global Selection 142

7.2.2.3 Streams and Blocks Selection 144

7.2.2.4 Component Materials Characteristics 145

7.2.2.5 Heaters Characteristics 147

7.2.2.6 Mixers Characteristics 149

7.3 Simulation Results 150

7.4 3D Model of Decanted TNT Reutilization Plant 151

7.5 Conclusion 152

References 153

Chapter No. 8: Pilot Plant Fabrication, New Blasting

Explosives Analyses General Conclusion and Suggestions for

Future Work


8.2 Pilot Plant Fabrication 155

8.2.1 Components of Pilot Plant 156

8.2.2 Technical Data of Pilot Plant 157

xii

8.3 General Hazards involved During Formulation of Explosives 157

8.4 Safety Precautions Taken During Blasting Explosives Formulation 158

8.5 Cost Analysis (Commercial Vs New Blasting Explosives) 160

8.5.1 Commercial Products (Blasting Explosives) and their Characteristics 160

8.5.2 New Blasting Explosives Formulated in Laboratory

and their Characteristics 161

8.5.3 Comparative Analyses of Commercial Vs Laboratory Formulated

New Blasting Explosives 162

8.5.4 Newly Formulated Blasting Explosives using Pilot Plant

with their Characteristics 165

8.6 Estimation of Timeline Required for Total Cost Recovery

of Industrial Scale Batch Plant (Approximately 300 kg) 167

8.7 Conclusion 168

General Conclusions 169

Suggestions for Future Work 170

xiii

List of Figures

Figure 1.1: Detailed Classification of Explosives 2

Figure 1.2: Graph showing Military High Explosives with their VOD (m/s) 12

Figure 1.3: Graph showing Military High Explosives with their Densities (g/cc) 13

Figure 1.4: Mechanical or Non-Electric Blasting Caps (Detonators) 14

Figure 1.5: Electric Blasting Caps (Detonators) 15

Figure 1.6(a) and (b): Typical Safety Fuse used During various Disposal Techniques 16

Figure 1.7: Detonation Cord filled with PETN Explosive 17

Figure 1.8: Tetryl CE used in Demolition 17

Figure 1.9: Munitions Hydraulic Breakdown Machine 22

Figure 1.10: Defuzing and Prime-Deprime Machines 23

Figure 1.11: Open Detonation of High Explosive Filled Shells 24

Figure 1.12: Open Burning of Propellant Charges used with Ammunition 24

Figure 1.13: Complete Life Cycle of Military Munitions 25

Figure 1.14: Dumping of Unserviceable Munitions 26

Figure 1.15 (a) and (b): Sea Dumping of Unwanted Munitions 27

Figure 1.16: Schematic Layout of an Explosive Train 29

Figure 1.17: Road Map for Completion of the Present Research Work 32

Figure 1.18: Explosive Decanting Plant with Decanted TNT 34

Figure 2.1: Diamond TG/DTA - Perkin Elmer Instrument 40

xiv

Figure 2.2: Main Components of TG Equipment 43

Figure 2.3: Working Principle of a TG Instrument 44

Figure 2.4: X-ray Diffraction (XRD) STOE Machine 45

Figure 2.5: Scanning Electron Microscope JEOL (JSM- 6490 LA) 47

Figure 2.6: (a) VOD Meter, (b) VOD Meter with Accessories and Box 48

Figure 2.7: Perkin Elmer FTIR Spectrum 100, MID IR 49

Figure 2.8: Decanted TNT with Decanted Shell Free From Explosives (FFE) 51

Figure 2.9: Open Air Experiments using Al as Thermite Composition 52

Figure 2.10: Fine Quality Saw Dust used in Research Work 53

Figure 3.1: Solubility of RDX in gram per 100 g of Solvent 66

Figure 3.2: Solubility of TNT in gram per 100 g of Solvent 66

Figure 3.3: SEM Images of US Composition B Explosive Sample at 5.0kV

and Magnifications of (a) 1500; (b) 3000; (c) 10000, respectively 70

Figure 3.4: SEM Images of Recovered TNT Explosive Sample at 5.0kV

and Magnifications of (a) 1500; (b) 3000; (c) 10000, respectively 72

Figure 3.5: SEM Images of Original TNT energetic material sample at 3.0kV

and Magnifications of (a) 1500; (b) 3000; (c) 10000 74

Figure 3.6: SEM Images of Recovered RDX Explosive Sample at 20-5.0kV


Figure 3.7: SEM Images of Original RDX Explosive Sample at 5.0kV


Figure 3.8: TG Curves of Five Different Samples 78

xv

Figure 3.9: DTA Curves of US Composition B, RDX and TNT Samples 79

Figure 3.10: XRD Patterns of Five Different Samples 80

Figure 3.11: FTIR Spectra of US Composition B, Recovered TNT,

Original TNT, Recovered RDX and Original RDX 81

Figure 4.1: Explosives Decanting Plant 87

Figure 4.2: SEM images of Decanted TNT Unsvc Sample at 5.0kV

and Magnifications of (a) 10000X; (b) 3000X; (c) 1500X 91

Figure 4.3: SEM images of TNT Svc sample at 3.0kV and Magnifications

of (a) 10000X; (b) 3000X; (c) 1500X 92

Figure 4.4: TG Curves of Decanted TNT Unsvc and TNT Svc Samples 93

Figure 4.5: DTA Curves of Decanted TNT Unsvc and TNT Svc samples 94

Figure 4.6: Calculation of Kinetic Parameters of (a) Decanted TNT Unsvc

(b) TNT Svc Sample, respectively 96

Figure 4.7: XRD patterns of Decanted TNT Unsvc and TNT Svc Samples 97

Figure 5.1: Open Air Experiments using Decanted TNT and Al Powder 101

Figure 5.2 (a) and (b): Percentage of Different Ingredients used with

Decanted TNT 103

Figure 5.3: SEM Images of Chinese TNT Svc Sample at Magnifications of

(a) 250; (b) 3000; (c) 5000; (d) 10000 107

Figure 5.4: SEM Images of Decanted TNT Unsvc Sample at Magnifications of

(a) 250; (b) 3000; (c) 5000; (d) 10000 109

xvi

Figure 5.5: SEM Images of TNT/15%Al Sample at Magnifications of

(a) 250; (b) 3000; (c) 5000; (d) 10000 111

Figure 5.6: SEM Images of TNT/26%Al Sample at Magnifications of

(a) 250; (b) 3000; (c) 5000; (d) 10000 114

Figure 5.7: TG Analysis of Chinese TNT Svc, Decanted TNT Unsvc,

TNT/15% Al and TNT/ 26% Al Samples 115

Figure 5.8: DTA of Chinese TNT Svc, Decanted TNT Unsvc, TNT/15% Al and

TNT/ 26% Al Samples 116

Figure 5.9: XRD Pattern of Four Types of TNT Samples 117

Figure 6.1: Safety Gadgets used During Explosives Formulation Process 124

Figure 6.2: Results of Abel Heat Tests 126

Figure 6.3: Layout of Demolition Stores used During Field Tests 127

Figure 6.4: Stepwise Images of Blasting Explosives

(Formulation Till Final Disposal) 128

Figure 6.5: VOD (m/s) Measurements of Different Samples including

Decanted TNT 129

Figure 6.6: VOD (m/s) Results of Laboratory Formulated Blasting

Explosives Samples 130

Figure 6.7: Density (g/cc) of Different Samples including Decanted TNT 131

Figure 6.8: Results of Abel Heat Tests 133

Figure 6.9: VOD (m/s) Measurement of Newly Formulated Blasting

Explosive Developed from Decanted TNT through Pilot Plant 135

xvii

Figure 6.10: VOD (m/s) Results of all New Blasting Explosives Formulated


Figure 6.11: Density (g/cc) of New Blasting Explosives Samples including

Decanted TNT 137

Figure 7.1: Flow Sheet of Pilot Plant for Decanted TNT 140

Figure 7.2: Components Specified from Aspen PLUS® Data Bases 142

Figure 7.3: Set up Selected for Steady-State Simulation Process 142

Figure 7.4: Selected SR-POLAR Property Method 143

Figure 7.5: Streams Specified in Simulation Process 144

Figure 7.6: Blocks Specified in Simulation Process 145

Figure 7.7 (a), (b), (c) and (d): Components with Characteristic Values

used in Simulation Process 147

Figure 7.8 (a), (b) and (c): Different Heaters with their Input Values

used in Simulation Process 149

Figure 7.9: Mixers with Input Values used in Simulation Process 150

Figure 7.10: 3D Model of Decanted TNT Re-utilization Plant 152

Figure 8.1: Pilot Plant Fabricated and Installed for New Blasting Explosives 155

Figure 8.2: Plant Room Constructed for Formulation of New Blasting Explosives 156

Figure 8.3: Pilot Plant with Newly Formulated Blasting Explosives and

Decanted Shells 157

Figure 8.4: Graph Showing Comparative Analysis of VOD (m/s)

for Commercial Explosives Vs New Blasting Explosives 163

xviii

Figure 8.5: Graph Showing Comparative Analysis of Cost (in PKR)

for Commercial Explosives Vs New Blasting Explosives 164

Figure 8.6: Graph Showing Comparison of VOD (m/s) for

Commercial Explosives Vs New Blasting Explosives 166

Figure 8.7: Graph Showing Cost Analysis of Commercial Explosives

Vs New Blasting Explosives Formulated through Pilot Plant 167

xix

List of Tables

Table 1.1: List of Most widely used Military High Explosives 9

Table 1.2: List of commonly used Primary High Explosives 11

Table 1.3: List of Demolition Stores used during Explosive Train Layout 29

Table 2.1: Percentage of ingredients used in Composition no. 1 (TAL-1) 54

Table 2.2: Percentage of each ingredient used in Composition no. 2 (TAL-2) 55

Table 2.3: Percentage of each ingredient used in Composition no. 3 (TAN) 55

Table 2.4: Percentage of each ingredient used in Composition no. 4 (TCAN) 56

Table 2.5: Percentage of each ingredient used in Composition no. 5 (TACAN-1) 56

Table 2.6: Percentage of each ingredient used in Composition no. 6 (TACAN-2) 57

Table 2.7: Percentage of each ingredient used in Composition no. 7 (TCAN-1) 57






Table 3.1: Experimental Vibrational Frequencies (cm-1) of RDX and TNT

Observed in FTIR Spectra along with their Descriptions 82

Table 4.1: Kinetic Evaluation Results of Decanted TNT Unsvc and Svc TNT 96

xx

Table 5.1: Materials Used in Formulation of New Blasting Explosives

Developed from Decanted TNT and Al Sample 102

Table 6.1: Compositions Used with Decanted TNT in Chemical Laboratory 123

Table 6.2: Various Types of Compositions Used with Decanted TNT 132

Table 7.1: Mass Flow Rate of Various Components Per Batch 144

Table 7.2: Components with their Characteristic Values 145

Table 7.3: Heaters with Specified Conditions Used in Simulation 148

Table 7.4: Simulation Results obtained through Aspen Plus® V8.4 Software 151

Table 8.1: Cost of Some of the Commercial Explosives Available in Pakistan

with VOD (m/s) 161

Table 8.2: Cost (in PKR) of New Blasting Explosives Formulated in

Laboratory with their Densities (g/cc) and VODs (m/s) 162

Table 8.3: Comparative Analysis of Cost (in PKR) of Commercial Explosives

Vs New Blasting Explosives Formulated in Laboratory 164

Table 8.4: Cost of New Blasting Explosives Formulated using Pilot Plant

with their Calculated Densities (g/cc) and VODs (m/s) 165

Table 8.5: Comparative Analysis of Cost (in PKR) of Commercial Explosives

Vs New Blasting Explosives Formulated using Pilot Plant 166

xxi

Abbreviations

Al Aluminium

CaAN Calcium Ammonium Nitrate

CaCO3 Calcium Carbonate

Comp B Composition B

DTA Differential Thermal Analysis

EPA Environmental Protection Agency

Ea Activation Energy (kJmol-1

) corresponds to a specific degree of

conversion

FTIR Fourier Transform Infrared

FBMR Fluidized Bed Membrane Reactor

HMX High Melting Explosive Cyclotetramethylenetetranitarmine)

HP Horse Power

NG Nitroglycerine

(NH, NI) Nitrogen Tri-iodide and Azoimide

OB/OD Open Burning/ Open Detonation

PAK-EPA Pakistan Environmental Protection Agency

PEPA Pakistan Environmental Protection Act

Pb(N3)2 Lead Azide

PFD Process Flow Diagram

xxii

PETN Pentaerythritol tetranitrate

R Gas constant (Jmol-1

K-1

)

RR Recoilless Rifle

R3 Resource Recovery and Re-utilization

RDX Royal Development Explosive (Cyclotrimethylenetrinitramine)

R&D Research and Development

RPM Revolutions per minute

SEM Scanning Electron Microscopy (SEM)

Svc Serviceable

STP Standard Temperature and Pressure

SOP Standard Operating Procedure

SMR Steam Methane Reforming

Tetryl CE Tetryl Composition Exploding

TNT Trinitrotoluene

TG Thermogravimetry

Unsvc Unserviceable

VOD Velocity of Detonation (m/s)

XRD X-ray Diffraction

1

Chapter No. 1

General Introduction

1.1 Energetic Materials

Human beings have had a tendency to use various types of firearms against their

adversaries for several centuries. In the past, people used to fight with swords and

battleaxes to safeguard their property, land and other possessions in the battlefields.

These practices, however, diminished after the invention of modern weapons and

ammunitions. Ammunition is used as a destructive material that is fired from a weapon

and is considered to be a most precious commodity. Its serviceability, consistency and

ability to produce the desired results during training and actual combat situations is of

prime importance. Special attention, safety and care is always required during the

filling, formulation and handling stage to enhance the shelf-life of ammunition under

ideal conditions. Ammunition mainly consists of a casing, initiating mechanism and an

explosive charge.

Explosives, also known as “Energetic Materials”, are very sensitive to external stimuli

[1-2]. Black powder, or gunpowder as it is better known, is considered to be the oldest

form of explosive known. Although the exact history about the inventor of black

powder is not known, the Chinese are considered to have started using black powder

during the 9th

century. Historians, therefore, mention black powder as the initial class of

explosive used by human beings for a wide range of applications. Initially, mining,

blasting, fireworks and signaling tasks were performed through use of different forms

of black powder. Later on, however, the use of black powder as a ballistic propellant

was introduced. In 1831, the first ever safety fuse was invented by the British

businessman William Bickford. Thus, with the invention of the safety fuse, the use of

black powder for practical purposes became safer and easier.

Despite the use of explosives in conventional military warheads, its application for

civilian purposes cannot be ruled out. Researchers around the globe are working in

2

different areas of interests to find newer version of explosives – carrying out in-depth

study on molecular dynamics and its structure. An explosive is a substance which

requires a suitable means of initiation i.e. a spark, flame, shock, impact or heat and then

undergoes a rapid chemical reaction to release a large amount of stored energy in the

form of immense heat and high pressure [3-4]. Based on sensitivity to external stimuli,

performance and characteristics, explosives are mainly classified under civilian and

military categories. Military explosives are further categorized into three main groups,

namely Pyrotechnics, Low explosives (Propellants) and High explosives. A flow chart

showing a broad classification of explosives is given in Figure 1.1. It is considered

prudent to briefly introduce all aspects of explosives so that the actual content of the

present research work is comprehended beforehand.

Figure 1.1: Detailed Classification of Explosives [5]

1.2 Constituents of Explosives

Explosives mostly contain Oxygen (O2) and Nitrogen (N2); in addition to oxidizing

elements like Carbon (C) and Hydrogen (H2) except Lead Azide (PbN), Nitrogen Tri-

iodide and Azoimide (NH, NI) etc. which contain no O2 in their compound. Explosives,

3

once initiated, give rise to chemical reactions where N2 and O2 molecules are liberated.

These separated molecules then immediately combine with oxidizing elements to

produce final products.

2C7H5N3O6 → 7CO + 5H2O + 7C + 3N2 ---------------------------------- (1.1)

In equation (1.1), a chemical reaction taking place during the thermal decomposition of

TNT has been shown. During the thermal decomposition, immense pressure and heat is

produced. Heat generated during such a process is the difference between the initial

heat required for initiation (stimuli) and the heat liberated during the formation of final

products which then form CO2, H2O, N2, etc.

1.2.1 High Explosives

Due to technological advancements in the field of explosives, the handling, formulation

and storage of high explosives has become safer and more secure. Generally, high

explosives have higher densities than other classes of explosives and they tend to

remain serviceable for a longer period of time. However, the rate of explosion

propagation for high explosives is very fast [6]. In other words, high explosives are

incredibly powerful – having a supersonic rate of decomposition. Their

Velocity of Detonation (VoD) varies between 3000 to 9000 m/sec. This speed

is a few times faster than the speed of sound. Additionally, the VOD of HMX in

comparison to the speed of sound is, interestingly, almost 28 times greater than

the speed of the sound. High explosives find its use in a variety of applications,

ranging from conventional warheads to blasting and other demolition tasks.

High explosives greatly differ in physical and chemical properties from other

classes of explosives. Generally speaking, high explosives require proper

means of initiation i.e. shock from blasting cap, etc. Once initiated, the burning

surface moves from particle to particle at very high speed owing to the granular

shape of the explosive. The speed of this burning surface denotes the type of

reaction taking place. Low explosives deflagrate, whereas high explosives

detonate. Therefore, the combustion of high explosives is defined as

instantaneous combustion.

4

1.2.2 Low Explosives

Contrary to high explosives – which undergo detonation on initiation – low explosives

decompose at a much lower burning rate, commonly known as deflagration. In this

case, the flame front travels with subsonic velocity [7]. Low explosives also differ

greatly from high explosives in their composition. Low explosives contain an

insufficient amount of O2 required for combustion, thus, oxidizer is added as a separate

ingredient during the manufacturing process. The main types of low explosives can be

categorized as propellants and pyrotechnics.

1.2.3 Distinction between Propellants, Explosives and Pyrotechnics

A detailed investigation of various classes of explosives is quite essential to

differentiate them from one another. All types of explosives are utilized in a variety of

applications. High explosives serve as the main filling in military munitions.

Propellants are used for propulsion purposes in rockets, gun munitions and missiles.

Similarly, pyrotechnic compositions are used for heat, smoke, light and sound effects,

where required [8]. All types of explosives can be easily distinguished on the basis of

their combustion behaviour. High explosives detonate and their burning rate is

extremely fast. However, propellant and pyrotechnic compositions deflagrate with

comparatively lower combustion rates.

1.3 Types of Explosions

As discussed previously, high explosives undergo detonation once suitably initiated.

However, the rate of burning dictates the type of chemical reactions. In the case of

detonation, supersonic shock waves travel from point of initiation to the far end,

whereas, the deflagration wave is of low intensity and thus travels at moderate speed

throughout the burning process. In simple terms, deflagration is a rapid chemical

reaction followed by the release of a large amount of gas and an intense heat wave,

pressure and high sound.

Explosion, or deflagration under confinement, is categorized as:

a. Chemical Explosion

b. Mechanical Explosion

5

c. Atomic Explosion

1.4 Deflagration (Fast Combustion)

In deflagration, combustion propagates at subsonic speed through an explosive

substance. It differs from detonation due to the speed of the shockwave. The

propagation speed of combustion is lower than detonation. The most commonly known

type of deflagration is an ordinary fire. However, once explosive materials are confined

into a suitable casing, deflagration converts into detonation. In this case, the detonation

wave travels at supersonic speeds instead of subsonic speeds. More specifically,

deflagration is a controlled type of combustion, whereas, detonation is uncontrollable

once initiated. Combustion, deflagration and detonation mainly differ from each other

on the basis of the speed of the burning.

1.5 Detonation (Supersonic Combustion)

It is commonly known that explosives are the most densely stored energy materials that

release a large volume of hot gases along with intense pressure on detonation. In the

process of detonation, the detonation wave travels at supersonic speeds leaving behind a

rapid chemical reaction. The detonation produces a chemical reaction which is highly

exothermic in nature [9]. A powerful shock wave is always required to initiate the

detonation process, I the absence of which the detonation phenomena will not occur. In

general, all military explosives – once properly initiated – undergo detonation.

However, the speed of the detonation wave varies according to the composition of the

explosive. Solid and liquid based explosives are more powerful as compared to gaseous

explosives since their velocities of detonations are greater. Detonation is also a form of

instantaneous combustion because a time interval is required for the instantaneous and

complete combustion of explosive particles during the detonation process. The speed

with which the detonation wave travels through explosive particles is termed as VoD,

also represented as “D”. Experimentally, VoD is measured with the help of a VoD

meter. Detonation is also classified into two categories, namely, high order detonation

and low order detonation. High order detonation occurs in high explosives having the

highest measure of VoD as a complete detonation of the explosive particles take place.

However, in the case of low order detonation, either a partial or incomplete detonation

6

occurs; where the VoD is lower than the optimally required velocity even with a

complete detonation. Possible causes of low order detonation are listed below:

a. insufficient power generated by blasting cap (detonator)

b. explosive charge affected by moisture, dampness or even corrosion

c. bad contact between blasting cap (detonator) and the explosive charge

d. manufacturing defects in explosive charge i.e. porosity, cracking,

cavities and other defects

e. existence of discontinuities and exudation in the explosive charge

1.6 Chemical Composition and Behavior of Explosives

Explosives can be categorized as either simple compositions or a mixture of various

elements blended together to form a chemical composition. Explosive compositions are

more aggressive and energy rich chemical compositions. Thus, when properly initiated,

they decompose swiftly with the liberation of a large amount of heat, gases and

immense pressure. The physical and chemical behaviour of reactants and products are

always different from each other. During the combustion or detonation process, a self-

propagating process takes place in the explosive particles which ultimately results in the

formation of shock waves and a bang. It is really important for the chemical

composition in any explosive to have a sufficient amount of O2 otherwise the reaction

fails to produce the desired products. For this purpose, an oxidizer is added to all

chemical explosives having suboptimal levels of O2 in their composition. The oxidizer

ultimately provides a sufficient amount of O2 for the sustenance of decomposition

reactions in order to produce the desired products. Commonly known oxidizers include

nitrates, chlorates, perchlorates, transition metal oxides, peroxides, etc. They are all

used as oxidizers in the formulation of different explosive compositions. It is pertinent

to mention that atmospheric O2 also acts as an additional oxidizer for some explosive

compositions, for example, Fuel- Air Explosives (FAE) [10].

1.6.1 Explosive Mixtures

Explosive mixtures are compositions where an oxidizer is mixed with fuel and other

ingredients mechanically. However, for high explosive compositions, an oxidizer is

blended in through pouring, melt cast and pressing techniques. All these techniques are

7

used to obtain high grades of precision and accuracy to avoid filling defects in high

explosives. A mechanical blending technique is also used in the case of low explosives

and propellants because they are rapidly burning materials and give rise to gaseous

production. These gases, in return, are utilized for mechanical work. In situations where

the ordinary mixing of oxidizer and low explosives is not feasible, water is added to

make a paste containing fine particles. All these efforts are made during the

manufacturing and filling process to eliminate any chances of cracks, voids or ruptures

appearing in the explosive mixture; a phenomenon most commonly seen to occur in the

dry season or during field transportation.

1.6.2 Explosive Compounds

High explosives are the chemical compounds which detonate under the influence of a

sufficient shock wave. They are formulated in such a way that the fuel and oxidizer are

blended together during the filling process, being tightly bonded. Since a mechanical

blending technique is considered unreliable in the case of high explosives, thus, more

reliable blending techniques such as melt casting, pouring and pressing techniques are

adopted.

1.7 Applications of Explosives

An explosive is a chemical substance that contains a large amount of useful energy

which can be utilized for multiple tasks according to the requirement. Explosives may

embody a single ingredient or a combination of two or more substances. High

explosives usually produce a high rate of shattering and destructive effects on the target

materials. Whereas low explosives, being less powerful, are used for specialized effects

like propulsion, smoke, light and heat. Therefore, the use of explosives in conventional

military munitions and in various commercial applications, including civil and

industrial purposes, cannot be ruled out. Since commercial explosives are relatively less

powerful than military explosives, they are employed in drilling, blasting, quarrying and

mining tasks. It is, therefore, important to select an explosive on the basis of its physical

and chemical characteristics.

8

1.8 Military High Explosives

Currently, a large number of various categories of explosives are available but not all of

them are being used for military purposes. On the contrary, military-utilized explosives

are fewer in number but are of a high-performance grade. Military grade explosives are

designed and manufactured to have very long shelf and in-service life (~20-25 years).

They are kept in specially designed and constructed storage accommodations under

ideal conditions. Every explosive intended for conventional military use is passed

through a certain number of bench-marks and proof tests. At each stage, the quality and

performance of the explosive is checked to ensure prolonged shelf life and high

performance during field service. Additionally, these rigorous tests are performed to

ensure that the final product is free from any kind of defects that may occur during the

formulation, filling and manufacturing processes. Defects, if any, are rectified in-situ

and the final data received after completion of tests is compared with standard

explosive data. It is of paramount importance for military grade explosives to function

precisely and consistently and also achieve the desired results once fired. Besides

performance criteria, the explosive must prove safe and reliable during the handling,

storage and transportation stages [10]. Some of the most widely used military high

explosives with their chemical formula are given in enlisted in Table 1.1.

9

Table 1.1: List of Most widely used Military High Explosives

S No. Military

High Explosive

Molecular

Formula

Structural

Formula

Velocity of

Detonation

(D)

1 2,4,6 Trinitrotoluene

(TNT) C7H5N3O6

6900

2 1,3,5-Trinitro-1,3,5-

triazinane (RDX) C3H6N6O6

8750

3 Pentaerythritol

tetranitrate

(PETN)

C5H8N4O12

8400

4 1,3,5,7-Tetranitro-

1,3,5,7-tetrazocane

(HMX)

C4H8N8O8

9100

1.8.1 Physical Properties of Military High Explosives

All military high explosives are used in a conventional manner against adversaries. Any

chance of misfire or malfunction during intended fire may lead to undesirable results,

understandably unacceptable in such situations. In order to maintain optimal

performance during a prolonged shelf life, military explosives need to qualify on the

basis of the following physical properties.

a. Availability and Cost

10

b. Sensitivity

c. Brisance and Power

d. Stability

e. Density

f. Volatility and Reactivity

g. Toxicity

1.8.2 Broad Categories of Military High Explosives

Based on the performance and combustion rate, military high explosives are further

classified into two broad categories i.e. Primary high explosives and Secondary high

explosives. Both vary in their rate of thermal decomposition; primary explosives burn

quickly (deflagrates). On the other hand, secondary high explosives, being more

powerful, detonate (burn with supersonic speed) once sufficient energy from a

shockwave is provided. Various categories of military high explosives differ from each

other based on their rate of sensitivity and performance; therefore, all these categories

are discussed here in detail to aid comprehension.

1.8.2.1 Primary High Explosives

Primary high explosives are designed to have a higher sensitivity (within reason),

increased initiation ability for the detonating explosives (boosters or intermediary

charges), a higher reliability and, finally, superior stability under ordinary conditions.

They are sensitive enough to be initiated by external stimuli, spark, friction, heat or

even a static charge. Their sensitivity is higher than PETN explosives due to which they

are used to initiate intermediary explosion i.e. Tetryl CE (Composition Exploding).

Since their sensitivity is greater than intermediary explosives, a small amount of

primary high explosive is filled into blasting caps (mg) to initiate the booster charge.

Primary explosives have low bulk densities and high specific areas. The most

commonly used primary high explosives are listed in Table 1.2.

11

Table 1.2: List of Commonly used Primary High Explosives

S.No Primary Explosive Chemical

Formula Characteristics

1 Lead Azide Pb(N3)2 Less hygroscopic, stable in storage at STP

2 Lead Styphnate C6HN3O8Pb Stable in storage at STP

3 Mercury

Fulminate Hg(CNO)2 Non-corrosive, less toxic and more stable

4 Silver Azide AgN3 Very toxic

5 Sodium Azide NaN3 Very acutely toxic

6 Lead Azide Pb(N3)2 Stable in storage at STP

7 Tetrazine C2H2N4 Less stable in nature

1.8.2.2 Boosters or Intermediary Charges

Boosters act as median explosives between primary high explosives and secondary high

explosives and are also termed as “intermediary charges”. They are designed to be more

stable and more powerful but less sensitive than primary high explosives. Boosters are

used to translate low power shock waves from primary high explosives in order to

detonate secondary high explosives. Tetryl CE is usually used as a booster in military

actions. In some cases, however, pellets of PETN (Pentaerythritoltetranitrate) and RDX

(Cyclotrimethylenetrinitramine) have also been used as boosters instead of Tetryl CE.

1.8.2.3 Secondary High Explosives

Secondary high explosives are most powerful high explosives, used as the main

bursting charges in military warheads and munitions. They differ in both physical and

chemical properties from other classes of explosives. On detonation, secondary high

explosives exert intense pressure on surrounding medium and induce the liberation of a

large amount of heat and gases. Mostly, secondary high explosive are rated according to

their VoD and employed according to their shattering effects. Confinement provides

12

additional power to the explosive as discharge gases are confined to a small area which

ultimately increases the shattering power of an explosive. Similarly, the VoD is directly

proportional to various physical and chemical properties such as initial density, initial

ambient temperature, pressure, particle size, charge diameter and degree of

confinement. Additionally, VoD of an explosive may be increased by decreasing the

particle size or increasing its charge diameter. It is universally considered that there is a

negative shift of about 70 to 80 percent in the case of unconfined velocity as compared

to a confined one. In Figure 1.2, a graph showing some of the most widely used

secondary high explosives with their VODs has been displayed. Figure 1.3 shows a

graph depicting military high explosives with the densities. HMX bears the highest

VOD of 9162 m/s [11].

Figure 1.2: Graph showing Military High Explosives with their VOD (m/s)

6900

8750 9162

7350

13

Figure 1.3: Graph showing Military High Explosives with their Densities (g/cc)

1.9 Commercial Explosives

A wide range of explosives are manufactured around the globe and utilized in a number

of applications. Some are used for military purposes while others find its use in civil

sectors. The basic manufacturing techniques of all explosives almost remains the same,

however, the chemical composition varies between various classes of explosives.

Commercial explosives are most prominently used in blasting, mining, quarrying,

underwater blasting applications, etc. Their formulation greatly differs from military

explosives, as commercial explosives are intended mainly for blasting, shattering and

brisance purposes. Some of the most widely used commercial explosives are briefly

described in subsequent sections.

1.9.1 Blasting Caps (Detonators)

Blasting caps also known as detonators are used to detonate more powerful explosives

such as booster or secondary explosives. Mostly blasting caps are encased in silver or

copper materials having a cylindrical shape. Very small amounts of super sensitive,

least stable and less powerful primary explosives are filled in blasting cap. A special

primary explosive called ASA compound is pressed into a commercial blasting cap.

ASA is a combination of lead azide, lead styphnate and aluminium. ASA compound is a

1.60 1.76

1.91 1.93

14

highly sensitive composition, thus special care is taken while handling the blasting cap

[10]. Two types of blasting caps are available in the market, i.e. mechanical and

electrical blasting caps. For initiation of mechanical or non-electric blasting, a cap

safety fuse filled with PETN is used. A safety fuse carries flame from initiators and

transmits it to the ASA compound in the blasting cap. Electrical blasting caps are initiated

through electronic source where heat passing through an electrical wire is transmitted to

the far end of the blasting cap. Explosive experts always go for extreme care while

handling all types of blasting caps. It must be noted that electric blasting caps are not used

where there is danger of any static charge or any chance of automatically current

generation. For safety purposes, all types of blasting caps are kept isolated and under

observation to avoid any accidents during storage, handling and transportation.

Specimens of mechanical and electric blasting caps (detonators) are given in Figure 1.4

and Figure 1.5, respectively.

Figure 1.4: Mechanical or Non-Electric Blasting Caps (Detonators)

15

Figure 1.5: Electric Blasting Caps (Detonators)

1.9.2 Safety Fuse

A safety fuse is a safety mechanism introduced during the demolition process where a

mechanical blasting cap is used. A safety fuse gives time delay for initiation of an

explosive train according to the user‟s choice. Thus, this unique feature, coupled with

the necessary safety arrangements, makes it convenient for use in demolition processes.

Internally, a safety fuse is covered with a black powder core and, externally, a

waterproof jacket is bonded. Safety fuses are designed to burn smoothly even in water

but its storage and handling in a wet environment is not feasible. Figure 1.6 (a) and (b)

shows typical safety fuses used during blasting and demolition processes.

16

Figure 1.6 (a) and (b): Typical Safety Fuse used During various Disposal Techniques

1.9.3 Detonating Cord

A detonating cord, also known as detonation cord, is similar in design to a

safety fuse but it has got a different composition. Just like a safety fuse, a

detonation cord is a flexible plastic tube filled with PETN explosive. A

detonating cord is made waterproof through exterior sheathing and plastic

wrapping and is used to transfer detonation wave from blasting cap (detonator)

to the booster charge at an extremely fast rate. Most importantly, a detonating

cord can easily be used for blasting of more than one charge simultaneously.

Figure 1.7 shows detonating cord filled with PETN explosive.

(a)

(b)

17

Figure 1.7: Detonation Cord filled with PETN Explosive

1.9.4 Explosive Boosters

Explosive boosters are used to enhance the power of a detonation wave. It acts as the

bridging material between the blasting cap (detonator) and the main bursting charge.

Tetryl CE (sometimes called Primer CE) is mostly used as an explosive booster in both

commercial and military blasting activities. However, with the advent of newer versions

of explosive boosters, Tetryl CE has been replaced by other compositions like PETN

and phlegmetized RDX pellets. Almost all types of explosive boosters carry a hole to fit

the blasting cap so that detonation waves are further transmitted to the main explosive

charge. Figure 1.8 shows Tetryl CE used as booster in demolition tasks.

Figure 1.8: Tetryl CE used in Demolition

18

1.9.5 Dynamite

Dynamite is a type of explosive used for blasting, mining, construction works, etc.

Initially, nitroglycerine (NG) based dynamites were used worldwide for mining and

blasting purposes. With time, ammonium nitrate (AN) based explosives replaced NG

based dynamites. There is also another type of military dynamite where NG is replaced

with a much more stable ingredient. This type of military dynamite is considered more

safe and secure during handling and in storage for longer period of time. It has been

learnt through experience that older lots of NG dynamite are hazardous for use as they

pose a serious threat during handling.

1.10 Environmental Impact

Adverse affects from the use of all types of explosives, whether military or commercial,

have been observed on human lives. Explosives not only pollute the environment but

also give rise to devastating effects when used in any form. More severely affected

areas are manufacturing and storage sites, filling areas, field fire and disposal grounds,

etc. There is also a considerable increase in global warming which is directly linked to

extensive use of Explosives. The Environmental Protection Agency (EPA), a leading

agency which dedicates its operations to the safe-guarding of the environment, has

shown greatest concerns over rapid environmental degradation globally. In order to

combat these issues, advance stage measures are required. One of the best alternatives

is to demilitarize all unwanted/ defective munitions and explosives through

environment friendly techniques.

1.11 Demilitarization

Although military munitions are considered very dangerous allies during conflict

situations against adversaries, their adverse effects on the environment during the

manufacturing, storage and disposal stages cannot be neglected [3]. If these munitions

become unwanted or unserviceable due to some reason, hazard prevails. The primary

hazard starts immediately once unwanted munitions start deteriorating, leading to

untoward incidents. Globally, different techniques are adopted for the disposal of all

unwanted and unserviceable munitions. These include Open Burning/ Open Detonation

(OB/OD), sea dumping, underground demolition, incineration and biological

19

degradation [4]. Although unwanted munitions are commonly disposed of through these

techniques, despite this, the environmental hazards start multiplying. Secondly, hazards

during the employment of disposal techniques are also serious issues which are

encountered a number of times internationally. Highly Explosives such as TNT, RDX,

HMX and PETN generate considerable hazards during detonation/ disposal. Such high

explosives contaminate soil surface and subsurface areas due to leaching of toxic

materials [1]. Other prominent hazards include air emissions, noise production and

residual materials. To safely combat all these issues, demilitarization procedures are

presently adopted in advanced militaries. Demilitarization is a very useful technique

where unwanted munitions are disposed of safely, thus addressing EPA concerns. Also,

approved policies relating to safety, security and the environment are followed [2].

1.11.1Dominating Features for Disposal of Unwanted Munitions

Multiple factors influence premature disposal of unwanted or unserviceable munition

during shelf life. A few dominating features are:-

a. exudation and other defects giving rise to environmental hazards

b. requirement of continuous maintenance during storage, thus becoming

unproductive and uneconomical

c. safety concerns specially while in storage, handling and transportation

d. obsolete or outdated type

1.11.2 Environmental Hazards

Almost all disposal techniques involve environmental hazards which pose a serious

threat to human lives. Unfortunately, munitions cannot be stored for a very longer

period of times once declared unserviceable or unwanted. Thus, an immediate disposal

procedure is adopted. Demolition has been practiced for quite some times around the

globe but due to inherent hazards involved, it is not practiced in advanced countries any

more. Similarly, OB/OD is considered ineffective due to air emissions, bang and

leaving behind residual materials. Residual materials, whether energetic or toxic,

ultimately contaminate the soil water being used by human beings, which is

understandably undesirable. Incineration is considered a somewhat acceptable

technique due to controlled and safe emission treating process and for this purpose

20

different types of incinerators are in use for disposal [5]. Other techniques involve

oxidation and biodegradation which are fairly similar to incineration. In both these

techniques, water is used for treating purpose which ultimately becomes waste water

and is equally hazardous. So it is beyond any question that all these disposal techniques

contribute to environmental pollution and hazards.

1.11.3 Economic Effects

All disposal techniques of unwanted or unserviceable munitions also involve use of

additional resources. Similarly, prolonged maintenance during storage necessitates use

of trained staff for monitoring of inventory management through check of ground

balances and condition of stocks. Pakistan, being a developing country, cannot afford to

maintain huge stocks of unwanted munitions in storage areas. Thus, a need is being felt

to adopt a proper mechanism for recovery and recycling of explosives, one where useful

energy stored in explosives is transformed through viable means.

1.11.4 Safety Concerns

Safety of human life and safety of other stored serviceable munitions from the threat of

all unwanted munitions are the two major concerns. Human life is in constant danger

from all unwanted and deteriorated munitions due to the threat of accidental initiation

during storage, transportation or while handling. Spontaneous combustion has taken

place a number of times, something that may ultimately lead to deflagration or even

detonation of the main charges of munitions. Moreover, staff involved in the regular

maintenance, care, preservation and final disposal procedures is continuously exposed

to accidental blasts or toxic fumes and gases.

1.11.5 Obsolete or Outdated Munitions

All outdated and obsolete munitions are considered waste material after the induction of

newer types of munitions. Outdated or obsolete munitions are then segregated from

serviceable or latest munitions to avoid accidental incorporation and are disposed of

accordingly. As mentioned earlier, keeping obsolete munition is highly unproductive

and hazardous and thus needs immediate disposal. For all those munitions where

recovery of components and explosives are safely manageable, disassembly and

21

demilitarization procedure are adopted. But in case of complete rounds where fuzing

and priming mechanisms are fixed, and removal of components and explosives is

inappropriate, then OB/OD, dumping, Sea dumping and demolition techniques are

adopted for disposal.

1.11.6 Steps involved in Demilitarization

Demilitarization of unwanted munitions is carried out in order to decant the explosive

from the shell body. The process of complete demilitarization involves a certain number

of steps. Every step in demilitarization involves careful handling of the munitions and

requires a safe environment for the handler. Each of these steps will be discuss briefly

for better assimilation. The main steps involved in the demilitarization process are listed

below:

a. transportation of unwanted munitions

b. unpacking and disassembly

c. removal of explosives

d. burning of explosives

e. resource recovery and re-utilization

1.11.6.1 Transportation of Unwanted Munitions

Transportation of unwanted munitions to the disposal site is a major part of a

comprehensive disposal procedure. All explosives produce large amounts of heat,

pressure and gases when detonated. Also, debris and splinters can travel a long distance

once munition is properly initiated. It is important that the disposal site be selected at a

suitable distance from general population, communities, living areas or other buildings,

etc. Proper arrangements for the transportation of unwanted munitions to the disposal

site are to be made. Standard Operating Procedures (SOPs) are to be strictly followed

and transportation is to be carried out according to the laid down SOPs.

1.11.6.2 Unpacking and Disassembly

Most of the munitions are seal packed or kept in close containers, boxes and packaging.

It is most important for unwanted munitions to be carefully transported to the disposal

site in proper packaging. The basic purpose of the packing material is to absorb jolts

22

and shocks during handling and transportation. Upon arrival at the site, munitions are

unpacked and laid out for proper disassembling. During disassembling process, all

components and explosives are removed so that it is ready for final disposal through a

suitable technique [6]. Fused munitions are also dissembled, with the removal of the

fuse being the first stage, to make it safe and secure for further handling. Thus,

arrangements for the disassembly of the complete round are made beforehand. Munition

hydraulic breakdown, defusing and prime-deprime machines are shown in Figure 1.9

and Figure 1.10, respectively.

Figure 1.9: Munitions Hydraulic Breakdown Machine

23

Figure 1.10: Defuzing and Prime-Deprime Machines

1.11.6.3 Removal of Explosives

Depending on the nature and type of explosives, recovery or removal of explosives is

carried out through specified techniques. In case of melt cast explosives such as TNT,

RDX and PETN, melting through steam or a hot water spray technique is adopted.

However, in some cases a nozzle jet spraying technology is applied for removal of

certain explosives, e.g. bombs, rocket motors and heavy calibre shells. Low power

explosives such as pyrotechnic compositions and propellants are removed through a

simple recovery machine.

1.11.6.4 Open Burning/ Open Detonation (OB/OD)

OB/OD has been one of the most widely used disposal technique for unwanted

munitions all around the world, especially after WW-II. This technique has been used

extensively as it provides a simple, cost effective and straightforward process of

munitions handling, laying and initiation. Not much effort is involved in laying

unwanted munitions for OB/OD; furthermore, also collection of material residues after

demolitions is quite an uncomplicated task. Secondly, OB/OD makes it possible to

dispose of almost all types of unserviceable munitions conveniently. However, this

technique was abandoned due to inherent hazards involved. One of the biggest hazards

is air emission where toxic gases like NOx, COx, etc. are liberated during OBOD.

24

Figure 1.11 demonstrates the laying down of high explosive-filled 155 mm gun shells

for Open Detonation [7]. Figure 1.12 shows the Open Burning of propellant charges

used with155 mm HE Shell.

Figure 1.11: Open Detonation of High Explosives Filled Shells

Figure 1.12: Open Burning of Propellant Charges used with Ammunition

25

1.11.6.5 Resource, Recovery and Reutilization (R3)

In the last phase of demilitarization, recovered explosives are either burnt or re-utilized

for useful purposes. Subsequently, metal parts and scraps of munitions are immediately

collected from disposal sites and reused in several ways. For example, metal parts

including scraps can be recycled in recovery plants, if the facility is available. On the

other hand, the same may be sold in the civilian market after altering the entire

specification, shape and design. All the metal parts, especially copper and brass made

components, are very costly and can be easily reutilized for other tasks. However, the

sale of munitions metal and scrap components is only allowed to authorized dealers

who are contractually bound to immediately change, and convert, all these military

components into specific molds not resembling military designs and shapes. Figure 1.13

illustrates the complete life cycle of military munitions from storage up until final

disposal.

Figure 1.13: Complete Life Cycle of Military Munitions

26

1.11.7 Dumping

Before the global move towards environmentally suitable disposal technologies,

dumping was carried out worldwide to get rid of unwanted munitions post World War-

2. All unserviceable, defective and unwanted munitions were dumped in remote areas

where it was considered to be safe for disposal. As unwanted munitions were never

disposed of permanently in this process, munitions used to remain alive on the dumping

site, with all their incumbent safety hazards and risks. A great numbers of incidents

have been reported of dumping site blasts where humans have lost their limbs and/or

lives. Secondly, environmental pollution due to exudation and leakage of explosives

also increased manifolds in this practice. However, this practice for munitions dumping

is not in practice any more. Figure 1.14 shows the dumping of unserviceable munitions.

Figure 1.14: Dumping of Unserviceable Munitions

1.11.8 Sea Dumping

In line with the dumping technique discussed previously, world armies also adopted sea

dumping of unwanted munitions for permanent disposal after WW-II. But the practice

of sea dumping lasted only until the advent of the “1972 United Nation Convention on

the Prevention of Marine Pollution by the Dumping of Wastes and Other Matter

(London Convention)” [8]. Through this Convention, the disposal of unwanted

munitions through sea dumping was banned forthwith. A major cause of this ban was to

27

protect sea life from chemical hazards produced by explosives and also from the rusting

of the metallic parts of munitions which immediately started upon exposure to water.

Figure 1.15 (a) and (b) demonstrates sea dumping of unwanted munitions.

Figure 1.15 (a) and (b): Sea Dumping of Unwanted Munitions

1.11.9 Demolition

Demolition is the most common disposal technique still in practice for disposal of

unwanted munitions (both military and commercial). In this technique, all unwanted

munitions are disposed of conveniently in a well prepared underground pit. Demolition

(b)

(a)

28

may seem quite similar to OB/OD but its harmful effects on the surrounding

environment are contained more suitably than in OB/OD. During demolition, an

explosive train (discussed in detail in subsequent paragraphs) is connected to the

unwanted munitions laid in a definite pattern inside an underground pit. Although a

great effort is involved in digging the underground pit for disposal of unwanted

munitions, the risks to human lives are minimized to a great extent with this technique.

On initiation, the explosive train produces a shock wave sufficient enough to detonate

the main explosive charge of munitions. The amount of debris and splinters resulting

from the demolition of unwanted munitions is less significant than in the process of

OB/OD.

1.11.10 Explosive Train

An explosive train can basically be defined as a “Progressive grouping of explosives to

detonate the main charge of a munition”. It involves the successive layout of

explosives according to sensitivity, moving from most to least sensitive, and also on the

basis of stability, in reverse order. It consists of a safety fuse connected to a blasting cap

which is further linked to a booster in order to detonate the main explosive charge.

Procedurally, the burning flame of the safety fuse gives sufficient energy to the blasting

cap which, in turn, produces a detonation wave. A detonating cord attached with the

blasting cap transfers the detonation wave travelling at supersonic speed to the booster

(Tetryl CE). Finally, the booster or intermediary charge further enhances the detonation

wave to detonate the main high explosive charge. Table 1.3, lists the demolition stores

with the filling details utilized in the explosive train. Any damage or disruption caused

during the layout or initiation of an explosive train will lead to the failure of the

detonation process during demolition. Figure 1.16 gives a schematic layout of an

explosive train.

29

Figure 1.16: Schematic Layout of an Explosive Train

Table 1.3: List of Demolition Stores used during Explosive Train Layout

S.No Item used Explosive Filling Purpose

1 Safety Fuse Gun Powder Flash Carrier

2 Blasting Cap Lead Azide, Lead Styphnate

and Mercury Fulminate

Detonation wave

Producer

3 Detonating

Cord

Pentaerythritoltetranitrate

(PETN)

Detonation wave

Carrier

4

Booster

Charge

Tetryl CE (Composition

Exploding)

Detonation wave

Enhancer

5

Plastic

Explosive

(PE-3A)

RDX 87%,Wax 11%,

Lecithin 1%

Main bursting

charge/ explosive

1.12 Environmental Protection Agency (EPA) and Pak-EPA

The Environmental Protection Agency (EPA) is an agency which works for the

protection of human lives and the environment. Initially, the EPA was established in

30

the USA on 02 December, 1970; subsequently, the EPA branched out its operations to

almost all countries. The EPA conducts a series of environmental assessment initiatives,

research operations and educational awareness programs globally. The EPA has written

legislation and regulations pertaining to environmental protection for enforcement in

the society. Its work mainly revolves around the protection of air, land, and water

resources; including a focus on hazardous wastes and materials. Pertaining to

explosives, the EPA has always voiced great concern about the wide spread disposal of

military munitions. Additionally, an increase in global warming, pollution levels in the

environment and the widening of the Ozone layer is seen to be directly linked to the

massive adversarial use of military munitions in the World. The use of high explosive-

filled munitions during the two major World Wars of 1914 and 1939 has left

immeasurable adverse effects on the human environment. The EPA has published

stringent regulations for the reduction of hazardous materials and policies for

environmental protection. Pakistan, being a nuclear weapon state, also takes full

responsibility to ensure environmental protection. Pakistan Environmental Protection

Agency (Pak-EPA) was established under section (5) of Pakistan Environmental

Protection Act, (PEPA) 1997. One of the main responsibilities of Pak-EPA is to prevent

pollution and to protect the environment from contamination resulting from explosives

through strict enforcement of PEPA-1997 rules & regulations. Additionally, Pak-EPA

gives approval for projects requiring Environmental Impact Assessment (EIA) and

deals with the issuance of Initial Environmental Examination (IEE) Certificates for

establishment of Environment Laboratories. Pak-EPA states, “Protection of

Environment is Our Moral and Legal Obligation. Support Pakistan Environmental

Protection Agency (Pak-EPA) in implementation of Pakistan Environmental

Protection Act (PEPA)”.

1.13 Motivation for the Present Research Work

Disposal of life-expired and unwanted munitions is a great challenge across the globe.

In the past, these unserviceable explosives were disposed of through conventional

disposal techniques such as Open Burning/ Open Detonation (OB/OD), sea dumping,

underground demolition, incineration and biological degradation. Production of

poisonous and toxic gases such as NOx, COx, etc. during these disposal techniques

31

have always been a great concern for Environmental Protection Agency (EPA). It is

very obvious that a completely hazard-free solution cannot be achieved in its entirety

but the best available option is to minimize these hazards through alternative means of

disposal. There is also an international consensus that due to the excessive use of

military and commercial explosives, global warming has increased to life-threatening

proportions. Moreover, the sustainability of a clean environment that enables economic

and social development has also been endangered due to hazardous materials. The

present work is aimed at finding the most feasible solution for the disposal of all

unserviceable explosives. Pakistan army, being one of the largest militaries in the

world, is holding huge stockpiles of unserviceable and unwanted munitions. There is an

ever-present need to devise a suitable mechanism for the reutilization of high

explosives. With this motivation, the present research work was initiated, and through

repetitive experimentations and field tests, new blasting explosives have been

formulated using decanted TNT, amongst other ingredients. All these newly formulated

explosives have qualified the required standards and are considered appropriate for

adoption as a blasting explosive to be used in mining, quarrying and other military and

commercial applications.

1.14 Scope of the Present Research Work

A brief literature survey has been carried out to find various fields of recent

research pertaining to demilitarization and reutilization of high explosives. The aim

was also to identify research work where thermal cum kinetic evaluation studies have

been performed on these high explosives. Important aspects of the literature survey

pertaining to various research areas are mentioned in the introductory section of each

chapter. A road map for the completion of the present research work is given in Figure

1.17.

32

Figure 1.17: Road Map for Completion of the Present Research Work

A brief literature survey, along with the comprehensive research work done in

specified fields, will be discussed in concerned chapters but some of the aspects are

also covered in subsequent paragraphs of this chapter.

33

The first two chapters of this thesis cover introductory sections and do not include any

part of the present research work. However, in Chapter 3, the first portion of the

research work has been discussed briefly. It contains solvent based recovery of TNT

and RDX from an unserviceable Composition B (US Comp B) explosives shell. Once

fully recovered, a comparative analysis of these recovered samples has been carried

out with serviceable samples of TNT and RDX using different instrumental techniques.

All the samples were investigated using simultaneous Thermo-gravimetric/ Differential

Thermal Analysis (TG/DTA). The most important aspect during this phase of research

was to maintain identical conditions for each sample under investigation so that

resultant values could be easily compared. Similarly, for the morphological study,

Scanning Electron Microscopy (SEM) was selected and all samples were subjected to

scanning through SEM. In addition to this, X-ray diffraction (XRD) and Fourier

Transform Infrared (FTIR) analyses have also been carried out to discover the

crystalline nature and spectroscopy of all the samples. Any change in surface

morphology, crystallinity and vibrational peaks of both serviceable and recovered

samples of TNT and RDX have been identified and recorded for further research work.

Chapter 4 of this thesis covers decanting of TNT from unserviceable munitions using

an explosive decanting plant (Figure 1.18). The decanting of explosives through boiler-

less decanting plant is one of the safest and most advanced methods in comparison to

conventional explosive recovery techniques. Thus, for all future requirements during

present research work, decanted TNT recovered from decanting plant was utilized.

34

Figure 1.18: Explosive Decanting Plant with Decanted TNT

Samples of decanted TNT, once fully drained from moisture contents, were further

compared with serviceable TNT samples using different analytical techniques. The

purpose of this comparison was to get a fair idea of the possible use of decanted TNT

for the formulation of new blasting explosives. Consequently, kinetic evaluation using

Horowitz and Metzger method was carried out for the calculation of activation

energies (Ea) and enthalpies of both the TNT samples. For this purpose, Battery

software was employed using a curve fitting program. It has been discovered through

the results obtained that decanted TNT has lower Ea in comparison to serviceable

TNT. Thus, sensitivity of decanted TNT has increased primarily because of the

presence of impurities, etc.

In Chapter 5 and Chapter 6 of this thesis, laboratory scale formulation of new blasting

explosives developed from decanted TNT and suitable oxidizers, fuels and stabilizers

have been discussed in details. Initially, analytical grade aluminium has been used as

thermite composition to enhance the blast efficiency of newly formulated blasting

explosives. However, high value of VOD makes it unsuitable for use in routine blasting

operations. Thus, ammonium nitrate (AN) and calcium ammonium nitrate (CaAN) have

been selected for use with decanted TNT. Field tests of all newly formulated blasting

explosives were conducted with the help of VOD meter (Explomet-fo-2000,

35

manufactured by KONTINITRO AG). The purpose was to ascertain the performance

and blast efficiency of all newly formulated blasting explosives. VOD results show that

almost all the new blasting explosive samples have qualified the required standards and

are considered appropriate for adoption as blasting explosives. Similarly, all the

samples have also achieved the desired level of stability and densities. All these results

have been recorded and briefly discussed in Chapter 5 and Chapter 6.

In Chapter 7, brief descriptions about the design of a pilot plant based on new blasting

explosives developed from decanted TNT have been given. Pilot scale plant has been

designed using Creo-parametric 3D modeling software. In later sections of the chapter,

the simulation of plant through Aspen PLUS® V8.4 software has been covered. After

successful simulation, results have been discussed in details in Chapter 6.

Chapter 8 adequately covers fabrication, installations and functional tests of pilot plant

based on new blasting explosives. Initially, dummy materials have been used to check

the functionality of fabricated plant. Once the plant has qualified all the criteria, real

experiments are performed using decanted TNT, CaAN, wax and CaCO3 to formulate

new blasting explosives. Adherence to the explosive safety regulations and Standard

Operating Procedures (SOPs) has been ensured at all stages of the experiments to

avoid any untoward incident. Performance and stability tests of all the newly

formulated blasting explosives through pilot plant were performed using VOD meter

and Abel Heat tests. Furthermore, a cost analyses of commercially available blasting

explosives vis-à-vis newly formulated blasting explosive in this research work have

been made. Surprisingly, all the newly formulated blasting explosives account for as

little as one-third of the cost of available commercial blasting explosives having

similar characteristics. All the acquired results have been thoroughly discussed in

Chapter 8 of this thesis.

36

References

[1] C.B. Aakeroy, T.K. Wijethunga, J. Desper, Chemistry-A European Journal 21

(2015) 11029.

[2] J.P. Agrawal, R. D. Hodgson, book on “Organic Chemistry of Explosives”, John

Wiley & Sons Ltd, England (2007).

[3] D. Guo, Q. An, W. A. Goddard, S. V. Zybin, F. Huang, J. Phys. Chem. C. 118

(51) (2014) 30202.

[4] T.Yan, K. Wang, X. Tan, J. Liu, B. Liu, B. Zou, J. Phys. Chem. C. 118 (40)

(2014) 22960.

[5] S. Kumar, P. Jain, M. Sharma, Importance of Forensic Investigation in

Explosion: A Case study, J Forensic Res. (2016).

[6] J. Akhavan, The Chemistry of Explosives 2 (2004).

[7] M.R. Anvekar, P. Kallolimath, Journal of Aeronautics & Aerospace Engineering

(2013).

[8] J.P. Agrawal, High Energy Materials: Propellants, Explosives and Pyrotechnics,

John Wiley & Sons (2010).

[9] J. Mathieu, H. Stucki. Military High Explosives, CHIMIA International Journal

for Chemistry 58(58) (2004), 383.

[10] L. Türker, Defence Technology 12 (6) (2016) 423.

[11] S. S. Samudre, U. R. Nair, G. M. Gore, R. K. Sinha, A. K. Sikder, S. N.

Asthana, Propellants Explos. Pyrotech. 34 (2009) 145.

37

Chapter No. 2

Experimental Techniques, Materials and Methods

2.1 Purpose of the Present Research Work

Experimental techniques form an essential part of research work when confirmatory

analysis is required. A number of experimental techniques are available to support

scientific work. Since the present research work aims at finding various morphological,

thermal and kinetic evaluations of various explosive samples, care has been taken to

adopt some of the major experimental techniques for this purpose. A brief description

of experimental techniques used in the present research work is given in succeeding

paragraphs.

2.2 Experimental Techniques

In the present research work, thermal analysis has been carried out using its various

experimental modes. Explosives can be easily investigated for their thermal evaluation

using these experimental techniques. Thermal properties are also directly associated

with kinetic parameters of explosives. For a brief evaluation of kinetic parameters,

thermal data of material under investigation is utilized. In all, the following

experimental techniques have been used for evaluation of explosives.

a. Differential Thermal Analysis (DTA)

b. Thermogravimetery (TG)

c. X-ray Diffraction (XRD)

d. Scanning Electron Microscopy (SEM)

e. Velocity of Detonation (VOD) Measurement

f. Fourier Transform Infrared (FTIR) Spectroscopy

2.3 Thermal Analysis

Thermal analysis is a very useful technique for the detailed investigation of any

chemical composition or material substance. Chemical and physical behaviour and

38

associated properties of elements, pure compounds and mixtures are simply analyzed

with the help of thermal analysis techniques. Due to their sensitive nature and erratic

behaviour, explosives are considered most complex organic compositions for thermal

analysis. Usually, investigation of explosives is carried out using thermal analysis

techniques. These methods are used primarily because very small quantities of an

explosive are needed for the analysis. Thus, small quantities of the samples make it

safer and easier to analyze different classes of explosives [1-3]. During thermal analysis

of a sample, any change in its properties, i.e. physical or chemical properties, occurs

due to sudden exposure to high temperature. Sample temperature is systematically

increased in a controlled manner. Sample and inner reference materials are placed in a

heating chamber and the difference in temperature over time is observed. Some of the

physical and chemical properties such as boiling point, melting point, phase transition

and thermal decomposition, etc. can be easily obtained using thermal analysis.

Similarly, heat flow measurement defines endothermic or exothermic behaviour of

material during thermal events. Moreover, useful information on activation energy (Ea),

frequency factor or pre-exponential factor (E) and reaction rate can be easily obtained

through thermal analysis. Thermal analysis can be effectively used for:

a. Description of various polymers [4]

b. Explosives characterization

c. Design and development of pharmaceutical [5]

d. Soil investigation and evaluation [6]

e. Thermal study of foods [7]

2.3.1 Thermal Analysis Methods

Different methods are available for the thermal analysis of a chemical composition or

substance. In each method, the material under investigation is observed for any specific

change in property with respect to temperature change. A few of the useful thermal

analysis methods are enlisted below [8].

2.3.1.1 Differential Thermal Analysis (DTA)

DTA is used for the measurement of temperature difference between sample and inert

reference material over time.

http://en.wikipedia.org/wiki/Differential_thermal_analysis

39

2.3.1.2 Thermogravimetery (TG)

TG provides useful information about change in sample mass in relation to change in

temperature or time. Change in mass loss can be further used for measurement of

various kinetic parameters of the sample.

2.3.1.3 Differential Scanning Calorimetry (DSC)

In DSC, difference in heat flow between sample and inert material is measured. Various

changes in melting point, boiling points, thermal decomposition temperatures and phase

transformations can be easily observed through DSC. This method is frequently used

for thermal and kinetic evaluation of different explosives [9-11].

2.3.1.4 Thermo Mechanical Analysis (TMA)

Unlike other methods, TMA provides very useful information about various mechanical

properties of the materials.

2.3.1.5 Dynamic Mechanical Analysis (DMA)

DMA is used to measure mechanical stiffness and damping of material.

2.3.1.6 Thermo-magnetometry (TM)

This method is employed where magnetic properties of a material are required.

2.3.1.7 Emanation Thermal Analysis (ETA)

ETA mainly gives observation about evolution of radioactive gas from a material. In

order to discover various properties of a sample, thermal analysis is carried out. In

general, thermal analysis is a set of the most effective tools to measure chemical, physical

and mechanical properties of a sample upon heating. Thermal cum kinetic evaluation of

explosives can be easily observed using thermal analysis methods. In the present research

work, Thermogravimetery (TG) and Differential Thermal Analysis (DTA) methods

have been used for investigation of different explosives which are briefly discussed.

2.3.2 Differential Thermal Analysis (DTA)

Differential Thermal Analysis (DTA) is a wonderful technique for the thermal analysis

of explosives. In the present research, DTA has been used extensively for the thermal

http://en.wikipedia.org/wiki/Differential_scanning_calorimetry

http://en.wikipedia.org/wiki/Dynamic_mechanical_analysis

40

and kinetic analysis of different explosives. It has been used to get useful information

on melting points, thermal decompositions, phase transformations, glass transitions

temperature, crystallization rates, etc. [12-14]. In DTA, a small quantity of sample

material is placed in Perkin Elmer ceramic crucible simultaneously with reference

material in another ceramic crucible for the thermal analysis. Both the materials are

then exposed to the required heating rate. The process for thermal analysis is carried out

under a controlled temperature program. Once the input is complete and the program

has been run, any change in temperature between sample material and reference

material is recorded and plotted as a function of temperature. The resulting curve is

called “Thermogram”. Through DTA, various kinetic parameters such as activation

energy (Ea), enthalpy etc. have been measured. Diamond TG/DTA-Perkin Elmer

Model Pyris instrument shown in Figure 2.1 has been used in the present research

work.

Figure 2.1: Diamond TG/DTA - Perkin Elmer Instrument

Reference materials used in DTA have a great effect on final results obtained from DTA

41

thermogram. The following characteristics must be kept in mind while selecting reference

material:-

a. Since reference material is used for comparative analysis, it must remain

inert thermally during the entire course of the thermal analysis.

b. Reference material should also remain neutral and non-reactive with

other ceramic crucible and thermocouples, etc.

c. Alumina or carborandum crucibles are considered most desirable

reference materials for thermal analysis as they possess almost all of the

above properties.

In addition to the above, a few other factors also have a direct impact and bear an

effect on DTA thermogram results. It is also important to know that all such factors

have a direct influence on TG curves as well.

2.3.2.1 Sample Related Factors

Sample characteristics and its nature are the key factors affecting the final results of

DTA curve. Some of the main factors are:

a. sample mass or weight

b. particle size and loading density of the sample

c. sample heat capacity and thermal conductivity

d. sample activation energy

2.3.2.2 Instrument Related Factors

a. heating rate of furnace selected for the sample

b. crucible material

c. crucible geometry

d. atmosphere of the chemical reaction

e. furnace type

f. exact position of thermocouple

g. instrument response and its specification

h. total time of investigation

42

For a brief thermal analysis of explosives, both TG and DTA techniques can be used

concurrently. As both TG and DTA are run under same environmental conditions,

kinetic parameters of any energetic material can be obtained easily using resultant

curves. In the present work, both TG and DTA have been used simultaneously.

2.3.3 Thermogravimetery (TG)

Thermogravimetry (TG) is a suitable technique used for the determination of energetic

material reaction. It is also termed as Thermogravimetric Analysis (TGA). In TG, a

small quantity of sample material is placed on a balance inside a heating oven and the

temperature is raised to the desired heating rate under a controlled temperature program.

Any change in weight gain or weight loss of the sample material is noted as a function

of temperature. In case of sample weight loss with rise in temperature, it may be linked

to the liberation of gaseous products due to chemical reaction, thermal decomposition of

sample material over time, etc. In cases where the sample has gained weight during TG,

it may be attributed to the chemical reaction of sample material with surrounding

environment, e.g. oxidation of metals [4]. In both cases of weight loss or weight gain,

sufficient useful information is obtained concerning the sample material. Either way,

obtained data regarding sample mass is correlated with other materials having similar

properties to recognize thermal events that have been observed in defined temperature

range. Weight vs. temperature curve plotted for the available data on sample material

gives very useful information about its thermal stability and decomposition. For the

measurement of possible changes in sample weight with temperature increases, thermo-

balance is utilized [5]. Based on all this information, TG analysis has been

comprehensively used for thermal analysis of explosives [15-17]. In the present work,

TG curves have been used for the measurement of thermal analysis and kinetic evaluation of

different samples of explosives. The main components of TG equipment are shown in Figure

2.2.

43

Figure 2.2: Main Components of TG Equipment

2.3.3.1 Working Principle of TG

In TG system, the sample material is filled in one pan whereas reference material is

placed in an adjacent pan. The two microbalances are linked with respective driving

coils. Any change in sample mass during DTA is observed closely with the help of

optical position sensors containing a slit. An optical beam is transmitted to the two

microbalances connected with driving coils through an optical position sensor. The

resulting current or input data is then passed to the driving coil to make sure that the slit

returns to its original location. It must be noted that sample weight loss or weight gain is

directly linked to the current passed by the microbalance to the driving coil. This way it is

easy to detect any change in sample mass with respect to reference material. Figure 2.3

shows the working principle of a TG instrument.

44

Figure 2.3: Working Principle of a TG Instrument

2.4 X-ray diffraction (XRD)

One of the most powerful and extensively used techniques for the identification of the

atomic or molecular structure of crystalline materials is X-ray diffraction (XRD). XRD

provides useful information about crystal structure of materials and is thus utilized in

the fields of Materials Science and Chemistry. Experts and research students working in

the fields of explosives widely use XRD for multiple reasons [18-20]. In this technique,

the incident X-rays are dispersed in var ious directions. This dispersion is caused

because of the X-ray‟s interface with the materials‟ atoms. The interference of an X-ray

may be constructive or destructive in nature. Bragg‟s law briefly explains the

constructive interference:

nλ = 2dsinθ

Here,

„n‟ shows an integer,

„λ‟ signifies incident X-rays wavelength,

„d‟ denotes the spacing between the planes and

θ represents the angle between the incident X-rays and set of crystal planes.

X-rays are electromagnetic radiations having a wavelength between 0.5-2.5Ao.

45

Within this wave length range, it is quite easy to find the crystal structure of any

materials at their atomic level. In the present research work, XRD has been used for the

description of serviceable and decanted TNT, RDX and Composition B explosives.

XRD is quite effective in identifying the residues produced as a result of the thermal

decomposition of the sample energetic material. In this work, XRD analysis was

performed using STOE Germany Theta-Theta Diffractometer, Germany; as shown in

Figure 2.4.

Figure 2.4: X-ray Diffraction (XRD) STOE Machine

The XRD instrument broadly consists of the following basic components:

a. An X-ray source usually named Monochromatic

b. Pan or holder for the sample

c. Main data collector or Scintillation counter

d. Cu and Kα X-rays

As discussed above, XRD is mostly used for the identification of the crystal structures

of materials and their atomic layout, etc. However, there is other useful information

which can also be deduced from the XRD analysis. Some of them are enlisted below:

a. recognition of phase composition

b. identification lattice parameters of unit cells

c. crystalline structure of materials

46

d. surface morphology/orientation

e. exact size of crystallite

2.5 Scanning Electron Microscopy (SEM)

SEM is a highly unique and resourceful technique being used by scientists and research

students around the world for multi-research in the fields of science and technology [21].

SEM works as an electron beam focused on the target material for brief scanning. A

specific signal is generated once the electron beam strikes the material surface. Structural

information as well as the composition of the sample material is obtained through the

action of the electron beam. In comparison with commonly used microscopes, Scanning

Electron Microscope produces extraordinary results. Due to the short wavelength of

the electron and its improved focusing qualities, SEM can attain a resolution of <1 nm.

The wavelength of white light is comparatively higher than the electrons‟ wavelength.

Because of the inherent limitations of this high wavelength, the focusing resolution of

latest model microscopes is not >250nm.

In the present work, SEM has been used effectively for the analysis of surface features

and morphologies of various types of high explosives such as TNT, RDX and

Composition B (Comp B). Additionally, newly formulated blasting explosives have

also been investigated through SEM. This technique has been used primarily for the

surface investigation of all serviceable, decanted and newly formulated blasting

explosives to determine possible changes which may have occurred during their shelf

life. This technique also gave an insight into the various defects; including porosity,

cracks, minor holes, and other structural changes; found on the materials‟ surface

during a comparative analysis of different explosives. For this purpose, a scanning

electron microscope made by JEOL (JSM- 6490 LA), Japan, has been used which is

shown in Figure 2.5.

47

Figure 2.5: Scanning Electron Microscope JEOL (JSM- 6490 LA)

2.6 Velocity of Detonation (VOD) Measurement

The Velocity of detonation (VOD) Meter is a very dynamic tool for the measurement of

explosive efficiency with regards to blasting power. It helps in the identification of various

classes of explosives for selection on the basis of their use and applications. The VOD

meter helps to determine the strength and the performance of the explosive. The

EXPLOMET-FO-2000™ (KONTINITRO AG made in Switzerland) has been used

during the field testing of almost all explosives. This instrument has an accuracy of

+0.1 microsecond (µs).VODs of all samples of explosives, i.e. serviceable, decanted

and newly formulated blasting explosives have been measured using VOD meter. The

VOD meter actually works as a digital counter for the recording of VODs up to 10km/s.

Optical fiber probes in VOD meters are used to transmit light emitted during the

detonation of an explosive sample. The VOD meter is connected to two probes which

are attached on either side of the sample material. Once the explosive is initiated, the

detonation wave travels through optical fibers and its velocity is recorded automatically

in the VOD meter, thereby acting as an electronic counter between 0.1 micro-second

and 10 seconds. The resultant velocity is then used to determine the blast efficiency of

explosives. The VOD meter finds its use in a vast variety of scenarios for the

measurement of the VODs of various explosives; including the military, commercial

48

mining and other civil industries. Figure 2.6 (a) and (b) shows a VOD meter and a VOD

meter with accessories and box, respectively.

Figure 2.6: (a) VOD Meter, (b) VOD Meter with Accessories and Box

(a)

(b)

49

2.7 Fourier Transform Infrared (FTIR) Spectroscopy

Fourier Transform Infrared (FTIR) Spectroscopy is a very dynamic technique used for

the qualitative structure analysis of any material. The infrared region is used for the

measurement of the transmittance or absorption spectra with the help of a spectrometer.

In FTIR spectroscopy, the existence of various functional groups attached to the sample

material is verified. This technique is also very useful for the identification of the band

position, peak intensity and shape of explosives. A structural analysis of different

explosives used during the present research work has been done with the help of FTIR

spectroscopy. The stretching and vibration of various bonds in the explosive transmit

and absorb an infrared light which is further used for analytical purposes. All further

information was obtained through intensity/ wavelength curves [10].

In this research, FTIR (FT-IR Spectrum 100 Perkin Elmer, MID IR) shown in Figure

2.7 has been used for the qualitative structure analysis of serviceable and unserviceable

explosives samples; with 1 cm−1 resolution in the transmission mode from wave

numbers 450–4000 cm−1. Small quantities of both categories of explosives have been

prepared according to the requirement and placed in the pallet holder. Next, the holder

was placed in the Perkin Elmer FTIR instrument mentioned above. The resultant

spectra of all the explosive materials were recorded at an ambient temperature.

Figure 2.7: Perkin Elmer FTIR Spectrum 100, MID IR

50

2.8 Materials Used

2.8.1 Oxidizers

During the present research work, new blasting explosives have been formulated using

decanted and recovered TNT along with other suitable ingredients. One of the

ingredients worth mentioning is an oxidizer which is used for maintaining the fuel

levels needed to burn properly during the detonation process. TNT, being an oxygen

deficient explosive, always requires a sufficient amount of oxidizing agent to increase

its energy and efficiency. In order to enhance the oxygen levels in new blasting

explosive compositions, commercial grade Ammonium Nitrate (AN) and Calcium

Ammonium Nitrate (CaAN) have been selected and used in different proportions

during research work. Purity levels of all oxidizers used in the present work are lower

than in analytical grades because of two reasons, i.e. cost effectiveness and its utility as

per the requirement of blasting explosives. Since commercial blasting explosives are

used for low profile tasks as compared to military applications, not much precision and

accuracy is required in terms of range and power. AN and CaAN have been purchased

from local markets, thus, ensuring that both the oxidizers are easily available during the

formulation of new blasting explosives on a large scale basis. Before embarking on the

impregnation of TNT with oxidizers, all oxidizers have been sieved through ~18 mesh

size after being finely ground.

2.8.2 Fuels

2.8.2.1 Recovered/ Decanted TNT

TNT is one of the most powerful explosives used for both military and commercial

purposes. TNT finds its application as a fuel and as an energizing material due to its

powerful nature, high VOD and thermal stability. Initially, unserviceable TNT was

recovered from Comp B explosive through a solvent based technique. However, for all

other experiments, unserviceable TNT was recovered from unserviceable munitions

through a decanting process. Both types of TNT were used as the main fuel in the

formulation of new blasting explosives. Due to the high energetic value of contents,

decanted TNT has been used in different percentages along with various other

ingredients for the formulations of new blasting explosives. Figure 2.8 shows decanted

51

TNT placed in a wooden box; alongside its decanted shell showing a residue free

surface post the decantation of TNT explosive.

Figure 2.8: Decanted TNT with Decanted Shell Free From Explosive (FFE)

2.8.2.2 Aluminium (Al) Powder

During the initial phases of the present research work, Al powder was used due to its

high thermal effect, high heat of combustion and ease of availability [22]. Al powder

not only enhances the blast energy of explosives due to its high calorific value but also

enhances its brisance and shattering power. Analytical grade Al powder produced by

Panreac (Spain) was purchased. The average particle size of the analytical grade Al

was 26.98 µm. Al powder was used with TNT recovered from Comp B explosive for the

formulation of blasting explosives. Experiments using analytical grade Al were carried

out in an open atmosphere for safety reasons as the heating of Al powder requires

special handling and care. Figure 2.9 shows an open-air experimental area set up for the

formulation of blasting explosives using Al as fuel.

52

Figure 2.9: Open-Air Experiments using Al as Thermite Composition

2.88.2.3 Saw Dust

Saw dust, also commonly known as wood dust, is a flammable material which can

produce sufficient amounts of heat and energy. Commonly available saw dust has been

purchased from the local market for simultaneous use with decanted TNT, as an

additional fuel in order to act as a blasting agent. Small quantities of the finest quality

saw dust has been used in different proportions during the experimentation process. The

main reason behind its use was to produce additional energy and to increase the overall

heat of the newly formulated blasting explosives. Figure 2.10 shows fine quality

sawdust used during the research work.

53

Figure 2.10: Finest Quality Saw Dust used in Research Work

2.8.3 Paraffin Wax

Paraffin Wax is commonly used for lubrication, insulation and candle work. However,

it can be effectively use as a fuel, a phlegmatizing agent and for waterproofing

purposes. Additionally, wax works as an anti-caking agent and a moisture-repellant.

Two types of waxes have been used in the present research work to determine their

utility with respect to cost, availability and ease of handling; the first being an

analytical grade wax (made by Merck, Germany, having a solidification point between

56-58oC) and the second being a commercial grade wax. After initial laboratory scale

experiments, the analytical grade wax was replaced with commercial grade wax due to

cost effectiveness and availability.

2.8.4 Calcium Carbonate (CaCO3)

Calcium Carbonate (CaCO3), also known as Chalk, is a very useful composition which

is used in a variety of civil applications. Due to its inherent characteristics as a sound

base, it can be effectively used as a free acid absorbent. Chalk has been used to stabilize

the sensitivity of decanted TNT. It also helps in reducing the degradation process of

explosives and increases their shelf life. A very small quantity (~1-2%) of chalk has

been used in different explosive formulations to get the desired results.

2.9 Compositions of Newly Formulated Blasting Explosives

During the entire course of the research work, a large numbers of experiments have

54

been conducted for the formulation of new blasting explosives developed from

decanted TNT. Some of the samples achieved the desired results while others failed to

do so. Almost all the newly formulated explosives have been characterized, tested and

analyzed through various instrumental techniques. Detailed compositions of all newly

formulated blasting explosives are mentioned below.

2.9.1 Compositions Formulated at Laboratory Scale

2.9.1.1 Composition No.1 with TNT and 15% Al (TAL-1)

In this composition decanted TNT has been used with 15% Al to increase the blast

effects and energy of the new formulation. Nitrocellulose (NC) as flammable compound

was added to the composition. Wax was added as an insulation and desensitizing agent.

Besides, methanol and dry lecithin were also added to the composition in small

quantities according to its requirement. The percentage of each ingredient used in

Composition no.1 (TAL-1) is shown in Table 2.1.

Table 2.1: Percentage of ingredients used in Composition no. 1 (TAL-1)

S. No Chemical used Percentage (%)

1 Decanted or Recovered TNT 56

2 Al powder 15

3 AR Grade NC 13

4 Methanol 1

5 Wax 14

6 Dry Lecithin 1

Total 100

2.9.1.2 Composition No.2 with TNT and 26% Al Powder (TAL-2)

In this composition, decanted TNT has been used with 26% Al to further enhance the

blast effectiveness of the new formulation. Similarly, NC % has been increased

slightly to see the final effect. The percentage of each ingredient used in Composition

no.2 (TAL-2) is given in Table2.2.

55

Table 2.2: Percentage of each ingredient used in Composition no. 2 (TAL-2)


1 Decanted or Recovered TNT 45

2 Al powder 26

3 AR Grade NC 14

4 Methanol 1

5 Wax 13

6 Dry Lecithin 1

Total 100

2.9.1.3 Composition No. 3 (TAN)

In this particular sample, decanted TNT was used with AN to determine the results for

comparison with CaAN samples. Results of Composition no. 3 are discussed in a

relevant chapter of this thesis. Table 2.3 shows the percentages of ingredients used in

this composition.

Table 2.3: Percentage of each ingredient used in Composition no. 3 (TAN)


1 Decanted TNT 7

2 AN 88

3 CaCO3 0.5

4 Wax 0.5

5 Sawdust 4

Total 100

2.9.1.4 Composition No. 4 (TCAN)

In this particular sample, a blasting explosive was developed from decanted TNT

using a sufficient quantity of CaAN as an oxidizer. The VOD and other field test

results show remarkable achievement, including cost effectiveness. Although, data in

literature form regarding use of CaAN with unserviceable TNT for reutilization

purposes is not available. Cost effectiveness, safety in handling and availability

56

aspects also makes it seem like the most practical candidate for use as an oxidizer.

Table 2.4 gives percentage-wise details of the composition used.

Table 2.4: Percentage of each ingredient used in Composition no. 4 (TCAN)


1 Decanted TNT 20

2 CaAN 74

3 CaCO3 0.5

4 Wax 0.5

5 Sawdust 5

Total 100

2.9.1.5 Composition No. 5 (TACAN-1)

In this composition, a mixture of CaAN and AN has been used to determine their

results. Wonderful results have been achieved which are discussed in detail in a

relevant chapter of the thesis. Table 2.5 gives percentage-wise details of the

composition used.

Table 2.5: Percentage of each ingredient used in Composition no. 5 (TACAN-1)


1 Decanted TNT 30

2 AN/ CaAN 60

3 CaCO3 0.5

4 Wax 0.5

5 Sawdust 9

Total 100

2.9.1.6 Composition No. 6 (TACAN-2)

In line with composition no. 5, different percentages have been used to determine the

final results which are discussed in a later chapter. Table 2.6 gives percentage wise

details of composition used.

57

Table 2.6: Percentage of each ingredient used in Composition no. 6 (TACAN-2)


1 Decanted TNT 15

2 AN/ CaAN 80

3 CaCO3 0.5

4 Wax 0.5

5 Sawdust 4

Total 100

All these newly formulated explosives have been analyzed through various thermal and

analytical techniques and results have been deduced accordingly.

2.9.2 Compositions Formulated through Pilot Plant

In order to achieve comparative results based on similar ingredients, different

percentages have been used in all compositions formulated through the pilot plant. The

purpose was to obtain VOD results having different values, so that required samples of

blasting explosive may be used according to their VODs. All these compositions have

been formulated through a personally fabricated plant using decanted TNT along with

other ingredients. Percentage-wise details of each composition formulated through

pilot scale plant are mentioned in Table 2.7 to Table 2.12.

2.9.2.1 Composition No. 7 (TCAN-1)

Table 2.7: Percentage of each ingredient used in Composition no. 7 (TCAN-1)


1 Decanted TNT 30

2 CaAN 60

3 CaCO3 2

4 Wax 1

5 Sawdust 7

Total 100

58




1 Decanted TNT 25

2 CaAN 70

3 CaCO3 1.5

4 Wax 0.5

5 Sawdust 3

Total 100




1 Decanted TNT 20

2 CaAN 75

3 CaCO3 1.5

4 Wax 0.5

5 Sawdust 3

Total 100




1 Decanted TNT 40

2 CaAN 50

3 CaCO3 1.5

4 Wax 0.5

5 Sawdust 8

Total 100

59




1 Decanted TNT 35

2 CaAN 60

3 CaCO3 1.5

4 Wax 0.5

5 Sawdust 3

Total 100

Composition No. 12 (TCAN-6)



1 Decanted TNT 25

2 CaAN 65

3 CaCO3 1.5

4 Wax 0.5

5 Sawdust 8

Total 100

2.10 Kinetic Evaluation Methods

2.10.1 Significance of Kinetic Evaluation for Explosives

Since explosives are energy rich compounds having very reactive and sensitive natures,

kinetic evaluation is significant prior to their handling, storage and transportation. It is of

paramount importance to evaluate explosives according to their thermal stability and

sensitivity. In the present research work, explosive data recorded during TG and DTA has

been used for the kinetic parameters evaluation of their thermal decompositions. Kinetics

evaluation is also important because it not only provides insight into the route of the

chemical reaction but also finds stability and suitability of different compositions with

each other. Thermal cum kinetic evaluation also provides assistance with the selection

60

and formulation of new versions of compositions along with their safety procedures.

Over a period of time, large numbers of thermal cum kinetic methods have been

devised for thorough evaluation of explosives. A key feature of TG/ DTA instrument is

that both the thermal analysis and kinetic evaluation of a particular energetic material is

obtained using a single instance of data.

It is also pertinent to mention that non-isothermal methods are better than conventional

isothermal techniques [23-24]. Some of the key features of non-isothermal methods are:

a. In all these methods, temperature scan of sample material over intended

range of temperature is a fast and easy process.

b. These methods provide continuous opportunity for the kinetic evaluation

of a sample over intended temperature range.

c. Non isothermal method sometimes form part of isothermal method as

the sample temperature has to be increased to the intended temperature

non-isothermally where the sample may be in danger of experiencing

some chemical reaction. However, these issues do not exist in the case

of non-isothermal methods.

d. All such methods need very little experimental data in a short span of

time.

e. For better results, numerous heating rates are chosen but where such an

option is not available, a single heating rate is still acceptable.

During this research, non-isothermal methods of kinetic analysis have been used.

Some of the most commonly used methods for kinetic evaluation are enlisted below:

a. Kissinger method

b. Ozawa method

c. Horowitz and Metzger method

d. Friedman method

e. Flynn–Wall–Ozawa method

2.10.2 Horowitz and Metzger Method

The Horowitz and Metzger method has been used in the present work as it can easily

manage to measure the activation energy (Ea) using a single heating rate in the

61

experiment. In this method, a reference temperature is determined and marked as Ts.

At this temperature, decomposition of any material under investigation reaches its

peak rate. The relationship shown in equation (2.2) helps in calculating Ts from TG

data obtained through analysis.

Ts = Wt / Wo = 1/e ------------------------------------------------------ (2.1)

Where, “Ts” denotes reference temperature, “Wt” is samples weight recorded at any

given temperature T, “Wo” is the total starting weight of the sample and “e” is the

exponential. In case the reference temperature “Ts” is already known, then difference

in temperatures ө (theta) can be calculated with the help of equation (2.2).

ө = T- Ts ------------------------------------------------------- (2.2)

Here “T” is temperature of the sample at any weight “Wt”. The “ө” is then plotted

against lnlnWo/ Wt. The value of Ea is then calculated using a gradient or the slope of

a nearly straight line obtained from the above mentioned graph [25].

Slope = Ea/ RTs2

------------------------------------------------ (2.3)

Where,

Ea is the activation energy,

R is the Universal Gas Constant and

Ts is the reference temperature.

62

References

[1] D. Ouyang, G. Pan, H. Guan, C. Zhu, X. Chen, Thermochimica Acta 513

(2011) 119.

[2] P.R. Patil, V.N. Krishnamurthy, S.S. Joshi, Propellants Explos. Pyrotech. 31

(2006) 442.

[3] L.Liu, G. He, Y. Wang, Journal of Thermal Analysis and Calorimetry 114

(2013) 1057.

[4] M.P. Sepe, Book on Thermal Analysis of Polymers, Smithers Rapra Publishing

(1997).

[5] D. Giron, Journal of Thermal Analysis and Calorimetry 68 (2002) 335.

[6] A.F. Plante, J.M. Fernández, J. Leifeld, Geoderma 153 (2009) 1.

[7] Y. Roos, Journal of Thermal Analysis and Calorimetry 71 (2003) 197.

[8] M.E. Brown, Book on Introduction to Thermal Analysis: Techniques and

Applications, Second Edition (2001).

[9] B. Berger, A. Brammer, E. Charsley, J. Rooney, S. Wirrington, Journal

of Thermal Analysis and Calorimetry 49 (1997) 1327.

[10] J.S. Lee, C.K. Hsu, C.L. Chang, Thermochimica Acta 392 (2002) 173.

[11] R. Sivabalan, M. Talawar, N. Senthilkumar, B. Kavitha, S. Asthana, Journal

of Thermal Analysis and Calorimetry 78 (2004) 781.

[12] H.-H. Licht, Propellants Explos. Pyrotech. 25 (2000) 126.

[13] Z. Ma, F. Li, H. Bai, Propellants Explos. Pyrotech. 31 (2006) 447.

[14] S.Pourmortazavi, M. Fathollahi, S. Hajimirsadeghi, S. Hosseini,

Thermochimica Acta 443 (2006) 129.

[15] X. Kang, J. Zhang, Q. Zhang, K. Du, Y. Tang, Journal of Thermal Analysis

and Calorimetry 109 (2012) 1333.

[16] J. Luman, B. Wehrman, K. Kuo, R. Yetter, N. Masoud, T. Manning, L. Harris,

H.Bruck, Proceedings of the Combustion Institute 31 (2007) 2089.

[17] Q.S. Kwok, R.C. Fouchard, A.M. Turcotte, P.D. Lightfoot, R. Bowes, D.E.

Jones, Propellants Explos. Pyrotech. 27 (2002) 229.

[18] G. Harding, A. Harding, Book on Counterterrorist Detection Techniques of

Explosives (2007) 199.

63

[19] L. Meda, G. Marra, L. Galfetti, F. Severini, L. De Luca, Materials Science

and Engineering: C 27 (2007) 1393.

[20] S.H. Ba, Z. Zhang, M.H. Yan, Z.X. Sun, X.P. Teng, Applied Mechanics

and Materials 217 (2012) 669.

[21] J.R. Verkouteren, Journal of Forensic Sciences 52 (2007) 335.

[22] Lemi TÜRK, Defence Technology 12 (2016) 423.

[23] S. Maitra, S. Mukherjee, N. Saha, J. Pramanik, Ceramica 53 (2007) 284.

[24] S. Vyazovkin, C.A. Wight, International Reviews in Physical Chemistry

17 (1998) 407.

[25] M.V. Kok, R. Pamir, Oil Shale 20 (2003) 57.

64

Chapter No. 3

Morphological and Thermal cum Kinetic Studies of

Assorted Explosives

3.1 Summary of the Present Research Work

Explosives experience widespread application in military as well as commercial

applications. They are being used for multiple purposes ranging from war field weapons

to the commercial mining and underwater blasting activities. Explosives are casted into

military shells by two different methods i.e. melt cast and press cast method [1]. Just

like other chemical compositions, explosives have a specified shelf life after which they

become unserviceable (US) for use, particularly in military operations. Out of various

classes of explosives, nitramines are ranked at the top due to their high energetic

properties and that is why technical application of these explosives is always useful [2-

3]. Composition B explosive is a mixture of 60% RDX, 40%TNT but in some cases 1%

wax is also added as desensitizing agent. Since both RDX and TNT are mostly used as

the main explosive charge for filling the military munitions, therefore, successful re-

utilization of these precious materials after completion of shelf life helps to reduce the

wastage of these explosives. A. Maranda et al., mentioned in their research that

application of unwanted explosives in the surface mining industry is in widespread

demand [4]. Similarly H. Krause investigated the conversion of military high explosives

into various forms of raw materials such as TNT into DAT and mentioned some of their

applicability into plastic industry [5]. Globally, efforts are underway for the safest

disposal of these unwanted explosives but these techniques are still hazardous for

human beings. J. C. Pennington et al., predicted in their research on unwanted

munitions that all degraded particles left over in the soil after a demolition process

produce adverse biological effects on human beings [6-8].

The present research work is aimed at successful recovery of RDX and TNT from US

Composition B using solvent based technique. This technique is not only safe but

65

environmentally acceptable because explosives are treated with solvent without heating

or exposing to external stimuli. After successful recovery of TNT and RDX, both the

samples have been investigated through various analytical techniques their thermal,

morphological and kinetic evaluations. Thermo-gravimetric/ Differential Thermal

Analysis (TG/DTA), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD)

and Fourier Transform Infrared (FTIR) techniques have been used during analyses of

both TNT and RDX. Special focus has been made on TNT explosive because of its

insensitive nature, thermal stability and relative cost-effectiveness [9-11]. To be more

confident about the recovered samples, original TNT and RDX were arranged. For in-

depth analyses, all the four samples of Recovered TNT and RDX vis-a-vis Original

TNT and RDX were used in the present work. SEM analysis has particularly been done

so that morphological changes between recovered and Original explosive samples could

be easily compared.

3.2 Experimental Conditions

3.2.1 Arrangement of Explosives

US Composition B was recovered arranged through defense organization for the present

research work. However, original TNT and original RDX were purchased from

Pakistan Ordnance Factories (POFs), Wah. After thorough literature study, analytical

grade chloroform was selected as suitable solvent for recovery of Composition B

ingredients (i.e. RDX and TNT).

3.2.2 Recovery of RDX and TNT from US Composition B Explosive

Composition B containing 59.5 % RDX / 39.5 % TNT and about 1% paraffin wax is a

melt cast explosive mixture. In order to recover TNT and RDX from US Composition

B using chloroform, the solubility of RDX and TNT in 100g of solvent have been

studied within temperature range of 20-25oC. Resultant data is shown in Figure 3.1 and

Figure 3.2 respectively [12].

66

Figure 3.1: Solubility of RDX in gram per 100 g of Solvent

Figure 3.2: Solubility of TNT in gram per 100 g of Solvent

Table 3.1 and Table 3.2 reveals that chloroform, being the most important solvent,

based on solubility difference, can be used for the recovery of RDX and TNT from US

Composition B explosive sample [12]. During experiment, small amount of chloroform

was added to US Composition B sample in a separating funnel. After proper shaking,

sample material was allowed to remain stationary on the clamp stand for a while so that

TNT and RDX could be completely recovered from US Composition B in two distinct

layers based on solubility difference in the chloroform. The process was repeated

67

several times until two distinct layers were visible. Brownish layer of TNT at the top

while white crystalline particles of RDX was present in the bottom layer. RDX was

drained out through bottom vent in the separating funnel. Recovered RDX was then

dried in the open air for further analysis. Chloroform solvent being very volatile in

nature completely evaporated in open air. In line with RDX, TNT particles were

collected from the bottom vent and subsequently dried through heating process just

below its melting point of 81+1 oC. Lastly, distilled water was added to left over

particles of TNT/ wax mixture so that insoluble wax floating on the top most layer

could be easily recovered and collected. Recovered TNT and RDX were then analyzed

through different techniques to find out their thermal behavior and surface morphology.

3.2.3 Analytical Techniques

Thermal and morphological analysis of all five samples including US Composition B,

Recovered RDX, Recovered TNT, Original TNT and Original RDX have been carried

out. Different instruments used during present research work included Scanning

Electron Microscopy (SEM-6490A JEOL made in Japan), Thermo gravimetric

/Differential Thermal Analyzer (TG/DTA- Perkin Elmer Model Pyris Diamond), X-Ray

Diffraction (XRD- made by Theta-Theta Toe, Germany) and Fourier Transform

Infrared (FTIR-Model Spectrum 100).

3.2.3.1 Scanning Electron Microscopy (SEM) Analysis

SEM, being one of the most versatile tools in identification of structural information,

can be employed in the field of explosive detection and identification. To carry out the

present work, Scanning Electron Microscope (SEM) instrument, 6490A JEOL has been

used. Variable voltages of 2-20kV and magnifications of 1500, 3000 and 10000 were

applied at different angles keeping in view the sensitivity and nature of the samples

3.2.3.2 Thermo gravimetric/ Differential Thermal Analysis

(TG/DTA)

TG/DTA is a very strong tool for thermal and kinetic studies of the sample under

controlled temperature program. Perkin Elmer Model Pyris Diamond TG/DTA (Thermo

gravimetric/ Differential Thermal Analysis) instrument available at SCME, NUST has

68

been used for the thermal analysis of various samples. All five samples were examined

using Perkin Elmer TG/DTA. This instrument works at a heating rate of 0.001oC/min to

200oC/min. In order to calibrate the apparatus, standards were run and then initial setup

for actual analysis was made. Nitrogen (N2) was used as purging gas for creation of

inert atmosphere. All five samples were subjected to a heating rate of 10oC/min and

temperature range was kept between 25oC to 350

oC during entire thermal analyses.

3.2.3.3 X-ray Diffraction (XRD) Analysis

X-ray Diffraction (XRD) analysis has also been carried out in the present research work

due to its wide range of investigation for a particular sample. Various parameters such

as crystal structure, atomic arrangement, phase orientation, lattice parameters, grain size

and density etc. of any sample can be easily identified.

3.2.3.4 Fourier Transform Infrared (FTIR) Spectroscopy

This instrument is particularly used to observe band position, shape and peak intensity

of various samples so that characteristics of functional groups can be identified. It has a

wave number ranging from 10000 cm-1

to 100 cm-1

. In this technique IR spectrum of

absorption, emission and Raman scattering of a solid, liquid or gas can be obtained.

3.3 Results and Discussion

During present work different results have been achieved through analytical techniques

which are briefly explained in the succeeding paragraphs. Sequentially all the samples

are discussed to get optimum information about each of the five explosive samples.

69

3.3.1 Scanning Electron Microscopy (SEM) Analysis

3.3.1.1 US Composition B

In Figure 3.3, US Composition B explosive sample in powder form was subjected to

SEM analysis and investigation. From SEM images it has been revealed that US

Composition B has spindle-like structure with multiple cracks and porosity of 160-521

nm size visible on the surface. The sample was examined at variable voltages between

3.0-5.0kV because at higher magnification and with increase in voltage, sample

behavior showed abrupt changes which proved unsafe for further analysis. The sample

has completed its shelf life; therefore various climatic changes may have rendered

multiple cracks and porosity in its surface. These cracks adversely affect the sensitivity

of this explosive and render it unsafe.

(a)

70

Figure 3.3: SEM Images of US Composition B Explosive Sample at 5.0kV

and Magnifications of (a) 1500; (b) 3000; (c) 10000, respectively

3.3.1.2 Recovered TNT

In Figure 3.4, a small quantity of Original TNT was investigated for its morphology. It

has been noted from the in- depth analysis that Original TNT has an even surface with

irregular blocks shape microstructure. Very few pores can be seen in the image which

shows that the sample is uniformed having integrated particle structure and is defect-

free explosive sample unlike Recovered TNT sample. Presence of cracks on explosive

surface has multiple reasons, some of which may be inappropriate storage conditions

and adverse climatic effects. An explosive is designed to be free from any kind of

(c)

(b)

71

filling or formulation defects, otherwise it may cause premature ignition of the

munitions. Similarly, exudation process can also be a cause of some defects during hot

climate. For the explosives, both the physical as well as chemical behaviors are most

important aspects. These include explosives crystalline or non-crystalline shape, pore

size and its density, ignition temperature etc.

(b)

(a)

72

Figure 3.4: SEM Images of Recovered TNT Explosive Sample at 5.0kV and

Magnifications of (a) 1500; (b) 3000; (c) 10000, respectively

3.3.1.3 Original TNT

In Figure 3.5, a small quantity of Recovered TNT sample was examined through SEM

analysis at 3.0kV and different magnification for its complete picture. Morphological

studies reveal that the sample has an irregular shape with no specific orientation.

Multiple pores in the size range of 247-608 nm are visible which render this sample

unsuitable for field utility as compared to Original TNT sample whose surface is

smooth and homogeneous [13]. Since sample was treated with water during separation

process, therefore chances for increase in porosity cannot be ruled out. However, a

major reason for large number of pores on the surface is long shelf life.

Multiple

tiny holes

(c)

73

(a)

(b)

74

Figure 3.5: SEM Images of Original TNT explosive sample at 3.0kV and

Magnifications of (a) 1500; (b) 3000; (c) 10000

3.3.1.4 Recovered RDX

In Figure 3.6, SEM analysis of Recovered RDX revealed that this particular sample is

more dangerous in nature especially once exposed to high temperature environment.

The sample was analyzed between voltages of 5.0-20.0kV, keeping in view its erratic

behavior. Sample has multiple cracks with width sizes of 212- 384 nm and varied

lengths. The surface seems to be more compact and flat in shape. Multiple cracks on its

surface are quite evident.

Even Surface

without tiny

holes or cracks

(c)

(a)

75

Figure 3.6: SEM Images of Recovered RDX Explosive Sample at 20-5.0kV

and Magnifications of (a) 1500; (b) 3000; (c) 10000

3.3.1.5 Original RDX

In Figure 3.7, SEM analysis of original RDX revealed that this particular sample has

spherical shaped morphology with multiple tiny holes spread across the surface.

Analysis was carried out at constant voltage of 5.0kV but at different magnifications of

1500, 3000 and 10000. No much difference has been observed in this particular sample

as compared to the Recovered RDX Sample. Surface is flat with multiple cracks of

170.88-475.39 nm sizes and varied lengths.

Multiple cracks

of ~2-6µm

(c)

(b)

76

(a)

(b)

77

Figure 3.7: SEM Images of Original RDX Explosive Sample at 5.0kV and

Magnifications of (a) 1500; (b) 3000; (c) 10000

3.3.2 Thermogravimetric (TG) Analysis

TG curves of all five explosive samples including US Composition B, Recovered TNT,

Original TNT, Recovered RDX and Original RDX are given in Figure 3.8. It has been

noted that TG curves for all samples exhibit nearly 100% mass loss in a single step.

Onset of mass loss for TNT samples both in Recovered and Original samples seems to

start near 165oC, whereas for RDX sample, mass loss is observed to start near 180

oC. A

rapid shift in mass loss has been identified between 180-245oC due to thermal

decomposition of TNT and RDX. Hence the total mass loss for all the samples over

controlled temperature range of 165-245oC was found to be nearly 99%.

Surface with less

no of tiny holes

(c)

78

Figure 3.8: TG Curves of Five Different Samples


Figure 3.9 shows DTA thermograms for various explosive samples including US

Composition B, RDX and TNT. Two different thermal behaviors have been found with

endothermic reaction occurring in first stage. Before melting of TNT, there is no

significant change in the thermal behavior of TNT and RDX. However, sharp

endothermic event can be observed between 81-83oC which corresponds to melting of

TNT [14-16]. Similarly, early stage melting of RDX is obtained near 190oC in case of

US Composition B and original RDX sample melting near 204oC [17-19] can be

deduced from Figure 3.7 above. This shift in melting point of RDX is due to presence

of more impurities in case of US Composition B sample and slightly less number of

impurities for Recovered RDX. In the next stage, exothermic peaks are visible for RDX

decomposition between 239-250oC, which corresponds to thermal decomposition of

RDX. However, for TNT, thermal decomposition between 235- 239oC occurs with

endothermic reaction. A few degrees temperature difference for all thermograms in

respect of RDX and TNT is probably because of the presence of impurities in

Composition B sample and variation of environmental condition during solvent

treatment of the samples.

79

Figure 3.9: DTA Curves of US Composition B, RDX and TNT Samples

3.3.4 X-ray Diffraction (XRD) Analysis

XRD results of RDX and TNT shown in Figure 3.10 reveal several different distinctive

diffraction peaks with varying intensity. It has been observed that both TNT and RDX

maintain crystalline structure in all types of state. XRD spectra exhibited these peaks in

the range of 10 to 40 (2 theta degree). The diffraction pattern of RDX can be easily

distinguished from TNT. Spectra revealed that TNT exists in monoclinic structure

possessing more stability than meta-stable state in both samples under observation.

Miller indices have been identified on XRD spectra with number of h, k, l values of

(-202), (004), (021), (-315) for TNT and (111), (210), (102) and (132) for RDX crystals.

Spectra showed that RDX exists in cubic crystal structure and its peak at h, k, l value of

(102) seemed to be more intense and sharp due to high crystalline nature. It has also

been noted that both Recovered and original RDX exhibits almost similar spectra.

Similarly, TNT peak with h, k, l value of (004) gives more intense value due to higher

degree of crystalline nature in TNT crystal. Experimental results so obtained are in

agreement with literature values for TNT and RDX in original form and thus proves its

existence in its actual state even after treatment with solvent.

80

Figure 3.10: XRD Patterns of Five Different Samples

3.3.5 Fourier Transform Infrared (FTIR) Spectroscopy

All selected explosives sample shown in Figure 3.11 were subjected to spectroscopic

characterization between 350 cm-1

to 3600 cm-1

and various absorption lines have been

observed in this range. Observed vibrational frequencies of Original and Recovered

TNT samples are 460.87, 639.41, 717.92, 717.60, 1351.62, 1351.72, 3095.98 and 3096.

However, for Original and Recovered RDX, numerous vibrations of 585.07, 585.10,

779.48, 779.51, 1386.51, 1038.49, 1591.79, 1591.88, 3074.74 and 3074.96 have been

identified. Table 3.1 gives experimental vibrational frequencies of TNT and RDX

observed in FTIR spectra along with available literature data on original explosive [20].

81

Figure 3.11: FTIR Spectra of US Composition B, Recovered TNT, Original

TNT, Recovered RDX and Original RDX

Spectral lines show similarity between experimental values and literature data. It has

been observed that RDX exists in original form with strong vibrational frequencies in

the range of 3074.74 to 585.07 cm-1

due to C-H, NO, C-N and N-N-O stretching.

However, TNT shows variant vibrational frequencies. At 3095.98 cm-1

, frequency

shows weak intensity due to C-H ring antisymmetric stretch whereas at 1351.62 cm-1

,

frequency band shows very strong C-C ring stretch. At lower frequencies of 639.41 cm-

1 and 460.87 cm

-1, band shows comparatively low intensity due to C-C ring stretch and

Ring torsion, respectively.

82

Table 3.1: Experimental Vibrational Frequencies (cm-1) of RDX and TNT observed

in FTIR Spectra along with their Descriptions

Name of

Explosive

Experimental

vibrational

frequencies (cm-1

)

of RDX and TNT

Available

literature data

on vibrational

frequencies

(cm-1

) of

Original RDX

and TNT

Description of

the normal

modes of

vibration

Peak

strength

RDX

(Original

and

Recovered)

3074.76

3074.96 3075

C-H stretch

(symmetric) Strong

1591.79

1591.88 1593 N-O stretch Strong

1386.32

1386.10 1390 C-N stretch Strong

1038.51

1038.49 1040 C-N stretch Strong

779.48

779.51 783 N–N–O bend Strong

585.07

585.10 590

Ring distortion

at C atoms

Medium

overlap

TNT

(Original

and

Recovered)

3095.98

3096.00 3097

C–H ring stretch

(antisymmetric)

Weak

1351.62

1351.72 1354 C–C ring stretch

Very

strong

639.41 639 C–C ring

bending Small

460.87 462 Ring torsion Very small

83

3.4 Conclusion

In this study various aspects like thermal behavior, possible degradation, crystalline

structure and morphology have been evaluated for US Composition B, Original TNT,

Original RDX, Recovered TNT and RDX. Results from these analytical techniques

indicate that the presence of impurities in these explosives have ultimately resulted into

degradation of these substances and thus rendered them US for further use. However,

these US explosive substances can be effectively reutilized in multiple applications

such as for civil, industrial and commercial purposes after the modification. Solvent

based technique used in the present research work has resulted into successful recovery

of TNT and RDX from US Composition B. The technique is quite safe, cost effective

and environmentally friendly process for reutilization of unwanted but most precious

commodity i.e. highly explosives. It has been noticed that recovered TNT and RDX

samples are of good purity and have various characteristics like melting point,

decomposition temperatures comparable with original TNT and RDX. Thus their

reutilization in commercial and military based applications cannot be ruled out.

84

References

[1] J. S. Lee, C. K. Hsu, Thermochim. Acta 371 (2001) 367.

[2] G. A. Olah, D. R. Squire, Chemistry of Explosives, Academic Press, San Diego,

CA. (1991).

[3] M. H. Keshavarz, J. Hazard. Mater. 162 (2009) 1557.

[4] A. Maranda, J. Nowaczewski, A. Paplinski, Defense Industries: Science and

Technology Related to Security, Kluwer Academic Publishers, Netherland

(2004) 361.

[5] H. Krause, Book on Conversion Concepts for Commercial Applications and

Disposal Technologies of Energetic Systems (1997).

[6] J. C. Pennington, J. M. Brannon, Thermochim. Acta 384 (2002) 163.

[7] J. M. Conder, T. W. La Point, J. A. Steevens, G. R. Lotufo, Environ. Toxicol.

Chem. 23 (2004) 141.

[8] X. Zhanga, Y. Lina, X. Shanb, Z.Chena, Chem. Eng. J. 158 (2010) 566.

[9] T. B. Brill, K. James, Chem. Rev. 93 (1993) 2667.

[10] G. T. Long, B. A. Brems, C. A. Wight, Thermochim. Acta 388 (2002) 175.

[11] T. B. Brill, K. J. James, Chem. Rev. 93 (1993) 2667.

[12] J. Yinon, S. Zitrin, Book on Modern Methods and Applications in Analysis of

Explosives (1996) 3.

[13] G. R. Miller, A. N Garroway, A Review of the Crystal Structures of Common

Explosives Part I: RDX, HMX, TNT, PETN, and Tetryl, University of Maryland

College Park (2001).

[14] T. Gibbs, A. Popolato (Eds.), LASL Explosive Property Data, University of

California Press, California (1980).

[15] S. V. Ingale, P. B. Wagh, R. Tewari, S. C. Gupta, J. Non-Cryst. Solids 356

(2010) 2162.

[16] S. Lixia, H. Rongzu, L. Jiamin, Thermochim. Acta 253 (1995) 111.

[17] R. Meyer, Explosives 3 (1987).

[18] G. Singh, S. P. Felix, P. Soni, Thermochim. Acta 426 (2005) 131.

[19] M. Fathollahi, B. Mohammadi, J. Mohammadi, Fuel 104 (2013) 95.

[20] A. Banas, K. Banas, M. Bahou, H. O. Moser, L. Wena, P. Yang, Z. J. Li, M.

Cholewa, S. K. Lim, C. H. Lim, Vib. Spectrosc. 51 (2009) 168.

85

Chapter No. 4

Comparative Analysis of Decanted TNT Vis-à-vis

Serviceable TNT for Reutilization as Blasting

Explosive


In this particular work, TNT has been decanted from an unserviceable munition through

properly designed and fabricated decanting plant installed in ammunition site. Although

in chapter 3, solvent based recovery of TNT from US Composition B for reutilization as

new blasting explosives has been discussed but to find out best possible recovery of

TNT through more convenient, safe and easy way, present research work has been

started. It has been noticed that this alternative method for decanting of TNT is easier

to handle, safe and economical as compared to solvent based technique. Besides, large

numbers of military calibres are filled with TNT alone, thus decanting makes it suitable

method for recovery of TNT from these shells. Cohen R et.al., Brill T B et.al., already

mentioned in their individual researches the presence and availability of TNT in pure

form as an explosive substance for use in various ways [1-4]. It has been extensively

used in military munitions as main charge and once declared unserviceable, TNT has

been disposed of through different techniques such as OB/OD, incineration, demolition,

etc. [5-6]. S. Ojha, in his PhD thesis very wisely covered various aspect of wasted TNT

including its possible hazards during conventional disposal techniques and also

mentioned about various forms of research work carried by scientists to mineralize TNT

[7]. These forms include phytoremediation, composting, advance oxidation and

photocatalytic degradations of waste TNT. Although these researches are equally good

for adoption but their utilities are very limited and thus could not spread too much as

alternate means for a very long.

In this work, decanting TNT was critically analyzed for its structural cum kinetic

studies so that surface morphology and also thermochemical decomposition of TNT is

86

observed. Since surface morphology and thermal characteristics clearly defines possible

reutilization of TNT or otherwise. A small quantity of decanted TNT in unserviceable

(Unsvc) form has been used for comparative study with serviceable (Svc) TNT. Both

the samples have been investigated for their thermal cum kinetic behaviour with the

help of available techniques such as TG/DTA, XRD and SEM. TG curves have further

been used for the determination of Arrhenius kinetic parameters, e.g. activation energy

(Ea) and enthalpy of formation of both Svc and Unsvc samples of TNT using Horowitz

and Metzger Method. Simultaneously, mass loss/ gain and thermal decomposition

ranges have also been evaluated using TG/DTA curves. For detailed structural analysis,

XRD technique has been used which gave distinct diffraction peaks showing crystalline

nature of TNT. Similarly, molecular structures of both TNT samples have been

examined through SEM analysis. SEM analysis revealed variety of defects present in

Unsvc sample. These defects include porosity, cracks, voids, etc. Interestingly, it has

been observed that the thermal as well as kinetic behavior of both the samples vary to a

great extent, keeping in view various aspects such as shelf life, environmental

conditions, manufacturing, filling and formulation processes. Additionally, resultant

data show that the decomposition temperature of decanted TNT has increased

substantially. Besides, prominent changes in activation energy (Ea) of both the samples

under investigation have also been observed.


4.2.1 Decanting of TNT from Unserviceable Munitions

Decanting is one of the most advance techniques for safe disposal of energetic

materials. It mainly works on the principle of melting out chemical composition filled

in munition through steam jet. In case of TNT, water is heated to 95oC through steam

generator and then spray onto the nozzle of the shell place upside down on decanting

table. Hot steam jet melts out TNT around 82oC which is then collected in receiving

trays placed underneath decanting table. Collected TNT is then dried in open air or

through hot air blow until 1% of the moisture contents remains. Steam water sprayed

onto TNT shells is drained to soakage pits where left over residues of TNT are also

collected through special wire mesh. Figure 4.1 shows decanting plant installed at

ammunition site.

87

Figure 4.1: Explosives Decanting Plant

4.2.2 Equipment of Decanting Plant

Decanting plant mainly consists of the following equipment:-

a. Overhead Water Tank for storage of water

b. Water Softening Unit

c. Feed Water Tank

d. Steam Generator

e. Steam Holder

f. Hot Water Tank

g. Decanting Table

h. Receiving Tray

i. Soakage Pit

j. Control Panel

88

4.2.3 Arrangement of TNT Samples

Two types of TNT samples have been used in the present research work i.e. TNT

Serviceable (Svc) and Decanted TNT Unserviceable (Unsvc). TNT Svc sample was

arranged through POF Wah. Whereas, TNT Unsvc was decanted from unserviceable

shell filled with TNT through previously described decanting. In routine procedure,

decanted TNT after drying for an hour is burnt in open air according to OB/OD

technique. However, in present research decanted TNT sample (unserviceable) has been

used for comparative analysis with serviceable TNT sample so that its viability for

further use in making blasting energetic materials can be worked out.

4.3 Analytical Techniques

Both the TNT samples have been analyzed through various instrumental techniques

used in the present work. These include SEM-6490A JEOL made in Japan, TG/DTA-

Perkin Elmer Model Pyris Diamond and XRD- made by Theta-Theta Toe, Germany.

4.3.1 SEM Analysis

SEM has been used for the extraction of structural and chemical information of both the

explosive samples under investigation through topographic imaging, e.g. fracture

surface, cracks etc. SEM version 6490A JEOL (made in Japan) has been used for the

microscopic study of samples from various dimensions which is available at SCME,

NUST. Different electron beam energies have been applied to obtain maximum output

from the SEM images with magnifications ranging from 1500X to 10000X.

4.3.2 TG/DTA

Wide utility of TG/DTA makes it one of the most versatile tools for the verification and

thermal cum kinetic studies of material sample using a controlled temperature

environment. In order to obtain thermal data about the samples, Perkin Elmer Model

Pyris Diamond TG/DTA instrument has been used. N2 has been used as purge gas to

maintain an inert environment for the samples. A heating rate of 10oC/min was kept

constant throughout the analysis along with temperatures ranging between room

temperature to 340oC.

89

4.3.3 XRD Analysis

XRD analysis, being a widely used method for the crystallographic identification of

material sample, has been selected to identify crystal structure of both the samples.

XRD analysis gave useful information about the samples which includes their

crystalline phases, atomic arrangement, orientation of a single crystal, lattice parameters

and density.

4.4 Kinetic Evaluation Methods

Literature finds various methods for the measurement of activation energy (Ea) and

enthalpy of explosive material. Few of the most commonly known methods are; Doyle

method, Coats and Red fern method, Horowitz and Metzger method, Freeman and

Carroll method and Newkirt method. Although all of the these methods are quite

accurate and reliable in use , however, present study for the calculation of Ea and

enthalpy of TNT explosive samples have been carried out with help of Horowitz and

Metzger method using a curve fitting program.



4.5.1.1 Decanted TNT Unsvc

For an in-depth analysis of Decanted TNT Unsvc, about 5mg of sample was examined

at 5.0kV electron beam energy and various magnifications through SEM instrument as

shown in Figure 4.2. All three images at different magnifications show an irregular

dough shaped morphology with no definite orientation of TNT sample. A predictable

number of pores in the size range of 247-608 nm are visible on the surface, giving an

indication of less possibility for potential use as military grade high explosive.

Similarly, a wide range of cracks on the sample surface renders it unsuitable for use in

pure form. One of the primary reasons for these pores and cracks may be linked to

treatment with hot water spray during its decanting process along with storage

conditions and handling processes.

90

Multiple

tiny holes

(a)

(b)

91

Figure 4.2: SEM images of Decanted TNT Unsvc Sample at 5.0kV and

Magnifications of (a) 10000X; (b) 3000X; (c) 1500X

4.5.1.2 TNT Svc

A small quantity of TNT in Svc form was utilized for analysis through SEM instrument

which is shown in Figure 4.3 above. The idea was to compare structural changes

occurring between Decanted TNT Unsvc and TNT Svc. Once exposed for investigation,

it is revealed that the TNT Svc sample has a smooth surface, with irregular pebble like

shape and no distinct orientation. The number and size of pores (between 240.00-

905.54 nm) visible on sample surface are fewer than those on Decanted TNT Unsvc

sample surface. Similarly, a very small quantity of cracks can be found on the

microstructure. It can be deduced from both the samples under investigation that TNT

Svc sample covers the basic requirement of pure explosive use for military grade

because of its clear, compact, smooth and homogeneous microstructure; unlike that of

the Decanted TNT Unsvc explosive sample. Variation in storage conditions, handling

procedure and climatic effects greatly affect the explosive‟s physical as well as

chemical properties and its shelf life.

(c)

92

Figure 4.3: SEM images TNT Svc sample at 3.0kV and Magnifications of

(a) 10000X; (b) 3000X; (c) 1500X

Even Surface

without tiny

holes or cracks

(a)

(b)

(c)

93


For thermal analysis, Decanted TNT Unsvc and TNT Svc were examined through

Perkin Elmer TG/DTA instrument. Figure 4.4 gives TG curves for both the samples

under investigations. Study of TG curves shows that weight loss occurred in both

samples in one step with both the samples diminishing nearly 98% around 285oC which

is in agreement with literature data [8-9]. Interestingly, onset of weight loss of both the

samples seems to occur around between 152-155oC. A rapid change in mass loss has

generally been observed between 175-266oC, which can be related to thermal

decomposition of both TNT explosive samples. Consequently, total weight loss for

Decanted TNT Unsvc sample under inquiry over prescribed temperature range of 155-

266oC is observed to be nearly 98%, whereas for Svc TNT sample, the decline in

weight loss seems to progress further and comes closer to 95% exhaustion around

285oC. This implies that the Decanted TNT Unsvc sample decomposes earlier than the

TNT Svc sample, which could be due to impurities, prolonged exposure to high

temperature environment, a long shelf life or even treatment with hot water spray

during decanting process.

Figure 4.4: TG Curves of Decanted TNT Unsvc and TNT Svc Samples

94


DTA curves for Decanted TNT Unsvc and TNT Svc have been observed in Figure 4.5

below. DTA thermogram indicate that both the samples nearly exhibit similar curves

until 1st sharp endothermic peaks for melting point of TNT between 81-83

oC are visible

[10-12]. Close examination reveals that TNT Svc started melting earlier than Decanted

TNT Unsvc explosive sample. Similarly, second endothermic event with slightly broad

peaks between 245-255oC corresponds to endothermic decomposition of both TNT

samples [13-14]. A slightly earlier decomposition of Decanted TNT Unsvc explosive as

compared to TNT Svc has been observed, which may be linked primarily to the

existence of the impurities in Decanted TNT Unsvc sample. However, presence of

moisture content in this particular sample may also contribute as impurity.

Figure 4.5: DTA Curves of Decanted TNT Unsvc and TNT Svc Samples

4.5.4 Horowitz and Metzger Method

Kinetic parameters like activation energy (Ea) and enthalpy of the decomposition for

Decanted TNT Unsvc as well as TNT Svc explosive samples have been determined

with the help of Horowitz and Metzger Method using TG curves. Graphs used for the

calculation of kinetic parameters are shown in Figure 4.6 (a) and (b) for Decanted TNT

Unsvc and TNT Svc samples respectively. Figure 4.6 (a) and (b), show that activation

95

energy (Ea) of Decanted TNT Unsvc explosive sample under controlled temperature

program is lower i.e. 203.40 kJmol-1

(48.613 kcalmol-1

) than the literature value for the

pure TNT i.e. 222 kJmol-1

(53.06 kcalmol-1

). However, activation energy (Ea) of TNT

Svc calculated from Horowitz and Metzger method is 217.78 kJmol-1

(52.05 kcalmol-1

),

which is in close agreement to the literature value for pure TNT [15]. On the other

hand, enthalpy of decomposition of Decanted TNT Unsvc explosive sample is

determined to be 203.20 kJmol-1

(48.56 kcalmol-1

), whereas, the same is 215.91 kJmol-1

(52.08 kcalmol-1

) for TNT Svc sample. It has been deduced from comparative study

that TNT Svc sample will result into a better performance in terms of its thermal

stability and sensitivity. Its rate of thermal decomposition and activation energy (Ea)

are well defined. On the contrary, Decanted TNT Unsvc explosive compound has

shown slight variation in its chemical characteristics which can be related to variety of

reasons such as ingress of moisture contents, impurity etc. All or some of these

properties may have affected serviceability of TNT and resulted into change of its

chemical or physical properties, for instance, decrease in activation energy and enthalpy

of decomposition. This decrease in Ea of the Decanted TNT Unsvc explosive has

negative impact on its thermal stability and shock sensitivity because thermally stable

compounds are more difficult to detonate.

(a)

96

Figure 4.6: Calculation of Kinetic Parameters of (a) Decanted TNT Unsvc

(b) TNT Svc Sample

Table 4.1 shows summary of kinetic evaluation results for two energetic materials

samples under investigation.

Table 4.1: Kinetic Evaluation Results of Decanted TNT Unsvc and Svc TNT

S.

No

Type of

Sample

Melting

point

(oC)

Activation

energy Ea

(kJmol-1

)

aLiterature

Value of Ea

for pure

TNT

(kJmol-1

)

Enthalpy

(kJmol-)

Decomposition

Range (oC)

1

Decanted

TNT

Unsvc

81.30 203.40 222 203.20 155 – 266

2 Svc TNT 80.81 217.78 222 215.91 155 – 285

a S. R. Ahmed et al. [15].

(b)

97


XRD results of Decanted TNT Unsvc and TNT Svc shown in Figure 4.7 reveal several

different distinctive diffraction peaks with varying intensity. During XRD analysis, it

has been noted that both the TNT samples has maintained their crystalline nature. XRD

spectra exhibited these peaks in the range of 20 to 40 (2 theta degree). The diffraction

pattern of TNT Svc can be easily distinguished from Decanted TNT Unsvc. XRD

Spectra revealed that TNT exists in monoclinic structure possessing more stability than

meta-stable state in both samples under observation [16]. Miller indices have been

identified on XRD spectra with number of h, k, l values of (004), (021), (-315), (1021)

for TNT. Similarly, TNT peak with h, k, l value of (004) is the most crystalline peak of

TNT spectra. Experimental results so obtained are quite close to the literature values for

pure TNT sample and thus proves its existence in its actual state even after aging and

treatment with hot water spray.

Figure 4.7: XRD patterns of Decanted TNT Unsvc and TNT Svc Samples

98

4.6 Conclusion

During present work, various characteristics of two different types of TNT explosive

samples such as thermal decomposition, microstructure analysis, surface morphology,

etc. have been carried out/ conducted. Results show that Decanted TNT Unsvc

explosive has gained impurity during storage, handling and transportation. Presence of

impurities has adversely affected its thermal properties, while its activation energy (Ea)

became lower than intended value thus making it more sensitive to accidental initiation

by friction or shock. Similarly, surface morphology of decanted TNT sample reveals

that it has become rough with multiple cracks and porosity thus giving rise to the

creation of hotspot. Likewise, earlier decomposition of decanted TNT sample reveals

that the sample contains impurities thus making it decompose prematurely. Although

numerous changes have been observed for the Decanted TNT Unsvc sample throughout

the analysis but interestingly it has maintained its crystalline nature even though after a

long shelf life, aging and exposure to variant climatic condition. This in-depth research

has given us hope that decanted TNT can be effectively used with other ingredients for

conversion into blasting explosives. This method of decanting is not only very simple,

easy in handling but also very quick in operation.

99

References

[1] R. Cohen, Y. Zeiri, E. Wurzberg, R. Kosloff, J. Phys. Chem. A. 111

(2007)11074.

[2] T. B. Brill, K. J. James, Chem. Rev.93 (1993) 2667.

[3] T. B. Brill, K. J. James, J. Phys. Chem. 97 (1993) 8759.

[4] T. B. Brill, K. J. James, R. Chawla, G. Nicol, A. Shukla, I. H. Futrell, J. Phys.

Org. Chem. 12 (1991) 819.

[5] J. Becanova, Z. Friedl, Z. Simek, Int. J. Mass Spectrom. 291 (2010) 133.

[6] J.C. Pennington, J. M. Brannon, Thermochim. Acta 384 (2002) 163.

[7] O. Sandeep, PhD Thesis submitted in University of California, LA. (1997).

[8] S. V. Ingale, P. B. Wagh, R. Tewari, S. C. Gupta, J. Non-Cryst. Solids 356

(2010) 2162.

[9] P. S. Makashir, E. M. Kurian, J. Therm. Anal. Calorim. 55 (1991) 173.

[10] T. R. Gibbs, A. Popolato, LASL Explosive Property Data University of

California Press Barkeley and Los Angeles, California (1980) 281.

[11] O. Srihakulung, Y. Soongsumal, World Academy of Science Engineering and

Technology 54 (2011).

[12] S. Lixia, Hu Rongzu, Li Jiamin Thermochim. Acta 253 (1995) 111.

[13] J. Yinon, S. Zitrin, Book on The Analysis of explosives Pergamon series in

analytical chemistry 3 (1984) 136.

[14] G. T. Long, B. A. Brems, C. A. Wight, Thermochim. Acta,388 (2002) 175.

[15] S. R. Ahmed, M. Cartwright, Book on Laser Ignition of Energetic Materials

John Wiley & Sons 1 (2014) 161.

[16] G. R. Miller, A. N. Garroway, Naval Research Laboratory 4555 Overlook

Avenue, SW Washington, DC. (2001) 20375.

100

Chapter No. 5

Formulation of New Blasting Explosives Developed

from Decanted TNT and Aluminium Powder


In this chapter, use of decanted TNT (decanting process has already been discussed in

chapter 4) with suitable ingredients such as fuels, oxidizers, stabilizers, etc. for the

formulation of new blasting explosives will be discussed. Since, existence of debris

from conventional disposal sites not only contaminates the soil but also creates severe

biological effects on living beings [1-3]. Nico H et. al., S.D. Harvey et. al., John Pichtel

et. al., Mark E. et. al., Paul Wanninger and Oldrich Machacek et. al., all these

explosive scientists have tried to recycle and reutilize various types of unserviceable

explosives and this practice is still in hand globally [4-9]. TNT has been selected for

reutilization through present research work due to its widespread application in military

munitions and also due its safe nature in handling and formulations [10]. In this chapter

use of aluminium (Al) powder with decanted TNT in different proportion have been

covered to see its final results. As we know that Al powder having high calorific value

has also been used in the past in different explosives formulation for both commercial

as well as military grades [11-12]. This is because Al particles contribute towards

energy level of explosives and thus enhance the blast effect of explosives [13-14].

Germans started extracting explosives out of the munitions casing and then letting these

materials burn in open air. Although their technique was comparatively easy to

implement but produced harmful results mostly due to uncontrollable combustion and

emission of toxic gases such as NOx, COx and SOx, etc. into the atmosphere [15].

101

5.2 Formulation of New Blasting Explosives Developed from

Decanted TNT and Al Powder

Two types of compositions have been formulated in SCME, NUST laboratories. All

aspects related to safety in handling of Al with melted TNT and other ingredients have

been kept in mind while doing these experiments. It is important to mention that all

these experiments were conducted in open air to avoid accumulation of any unwanted

toxic gases as addition of Al is highly exothermic in nature. Figure 5.1 shows layout of

experimental setup for formulation of blasting explosives using decanted TNT and Al

powder. In later part of the experiments, all samples have been characterized through

various analytical techniques available in SCME, NUST. Results obtained from

analytical methods have been noted and interpreted accordingly.

Figure 5.1: Open Air Experiments using Decanted TNT and Al Powder


5.3.1 Formulations Process

Formulations of new blasting explosives using decanted TNT and Al powder carried

out at specially designed safe yard of SCME, NUST laboratories, involved various steps

which have been discussed in succeeding paragraphs. List of different ingredients

including decanted TNT is given in Table 5.1.

102

Table 5.1: Materials Used in Formulation of New Blasting Explosives Developed

from Decanted TNT and Al Sample

S. No Material used Specifications Company/ Supplier

1 Decanted TNT Unsvc Military Grade Ammunition installation

2 Nitrocellulose (NC) Military Grade Government defense

sector

3

Aluminium powder (Al)

(average particle size 45

µm)

Analytical Grade Panreac

4 Methanol Analytical Grade Sigma-Aldrich (Riedel-de

Haen)

5 Paraffin Wax Analytical Grade Merck / MP Biomedicals

6 Dry Lecithin Analytical Grade Expert Scientist/

Germany

7 Glycerin Analytical Grade Scharlau/ Spain

8 Calcium Carbonate Analytical Grade Sigma-Aldrich (Riedel-de

Haen)

During initial experiments using decanted with Al powder, melted paraffin wax was

added to dry lecithin in a beaker and the mixture is stirred continuously at selected rpm.

Simultaneously, a small quantity of nitrocellulose (NC) was mixed with methanol and

then poured into wax mixture prepared earlier along with CaCO3. Upon compete

mixing; the whole blend was poured in an open pan. Finally, a small quantity of

decanted TNT unsvc was melted and subsequently added to the whole blend along with

moderately heated free flow wax coated Al. In this step, a beaker containing whole

blend of different ingredients was kept in a specially designed container filled with

glycerin to serve as an oil bath; the aim being to avoid direct contact of heat with beaker

containing decanted TNT and other materials. Percentage of Al was successively

changed during number of experiments to get an optimum value of newly formulated

TNT/Al based blasting explosive. After complete mixing of the blended, a small

quantity of newly formulated TNT/Al blasting explosive was used for advanced

analysis and characterization.

103

5.3.2 Percentages of Ingredients used during Experiments with Al

Powder

During these experiments all ingredients previously mentioned in Table 5.1 have been

used. Figure 5.2 (a) and (b), give details of each ingredient used during experiments,

respectively.

Figure 5.2 (a) and (b): Percentage of Different Ingredients used with Decanted TNT

1

14

1

13

15

56

45

26

14

1

13

1

(b)

(a)

104

5.3.3 Characterization of Serviceable and Unserviceable Explosives

Four types of explosives samples i.e. Chinese TNT serviceable (svc), decanted TNT

(unserviceable) unsvc, TNT/15%Al and TNT/26%Al have been used during this

particular research work. All the samples have been thoroughly investigated using

SEM, TG/DTA and XRD techniques. SEM analyses have been done with intention to

see apparent changes in the structure and morphology of all four samples. For scanning

purpose, SEM-6490A JEOL (made in Japan) has been used. Various magnifications of

250-10000 times were applied during scan process of all four samples at different

angles. For thermal cum kinetic studies of all four samples, Perkin Elmer TG/DTA

instrument have been used. Like previously conducted analyses, N2 gas has been used

as purging gas to produce inert atmosphere. Small quantities of all four samples have

been subjected to non-isothermal environment having controlled temperature program.

The whole examinations were conducted between temperature ranges of 25oC- 325

oC.

Controlled heating rate of 10oC/min was kept during entire analyses for all four

samples. Simultaneously, all these samples have also been characterized through XRD

using Theta-Theta (Toe), Germany made instrument. XRD have been used to get

valuable information about various parameters such as crystalline phase and orientation,

structural properties and lattice parameter, etc.

105



5.4.1.1 Chinese TNT Svc

In Figure 5.3 below, small quantity of Chinese TNT Svc has been analysed for an in-

depth morphology. Closer observation reveals that Chinese TNT Svc has a flake-type

microstructure with few tiny pores and cracks on its surface. These voids may be linked

to the filling, handling and processing defects. Explosives are mostly classified with

regards to their various physical and chemical properties such as shape, size and density

of powder particles along with its thermal and kinetic properties. Therefore, minor

defects in filling and formulation processes or inappropriate handling while in storage

may give rise to an untoward situation.

Spindle like

surface

(a)

106

Surface with visible

cracks on places

(b)

(c)

Cracks of

~2-5 µm visible

on surface

107

Figure 5.3: SEM Images of Chinese TNT Svc Sample at Magnifications

of (a) 250; (b) 3000; (c) 5000; (d) 10000

5.4.1.2 Decanted TNT Unsvc

In Figure 5.4, small quantity of unsvc decanted TNT sample has been examined at

varying magnifications. SEM images show that the sample has an irregular granular-

type shape with comparatively more pores and cracks visible on the surface of

microstructure [16]. As decanted TNT Unsvc was treated with steam jet during

decanting process, therefore the number of pores and cracks were observed to have

increased. Resultantly, impurities in the decanted TNT Unsvc sample have increased

manifold. Presence of such a large numbers of pores and cracks are prone to affect the

sensitivity and thermal characteristics of explosives.

Visible pores and

cracks on surface

(d)

108

(a)

(b)

Multiple tiny

holes and pores

on the surface

109

Figure 5.4: SEM Images of Decanted TNT Unsvc Sample at Magnifications

of (a) 250; (b) 3000; (c) 5000; (d) 10000

5.4.1.3 TNT/15%Al Sample

Figure 5.5 shows SEM images of newly formulated blasting explosives developed from

decanted TNT and 15% Al powder. In order to check the difference in addition of

various ingredients to decanted TNT, SEM analyses of the newly formulated samples

have been carried out. From Figure 5.5, it can be easily deduced that the structure of the

(c)

(d)

Multiple cracks

~5-8 µm visible

on the surface

Slightly smooth

surface

110

sample is spindle like having smooth, uniform and homogeneous surface. More

precisely the newly formulated blasting explosive has fewer numbers of pores and

cracks and thus its surface is very neat and clear. This shows that addition of various

ingredients to decanted TNT unsvc have overall very positive impacts on the structural

morphology.

Rough surface with

dough shape morphology

(a)

(b)

Compact surface

with fewer no of

pores and cracks

111

Figure 5.5: SEM Images of TNT/15%Al Sample at Magnifications

of (a) 250; (b) 3000; (c) 5000; (d) 10000

5.4.1.4 TNT/26%Al Sample

Figure 5.6 shows SEM of newly formulated blasting explosive developed from

decanted TNT with 26% Al powder. The percentage of Al has been increased in this

particular experiment to see the impact of addition of Al on surface morphology and

physical characteristics of newly formulated blasting explosive. Explosive sample was

(c)

(d)

Smooth surface

with negligible

number of pores

and cracks

More compact

surface without

pores and cracks

112

scanned at varying magnifications set for previous sample under investigation. It has

been observed that TNT/26%Al sample has spheroidal type shape with smooth and

integrated particle surface. SEM images of the two newly formulated blasting

explosives developed from decanted TNT with addition of 15%Al and 26%Al,

respectively show remarkable changes in their surface morphology. It has been noticed

that addition of more quantity of Al powder has amazingly reduced the number of pores

and cracks besides giving clear, compact and homogeneous particle surface. Since,

increased number of pores and cracks tend to increase chances of premature

degradation of explosives during prolonged storage.

(a)

Spheroidal type shape with

smooth and integrated

particle surface

113

(b)

(c)

More smooth and

integrated surface

Surface without

pores and cracks

114

Figure 5.6: SEM Images of TNT/26%Al Sample at Magnifications

of (a) 250; (b) 3000; (c) 5000; (d) 10000


In Figure 5.7 all four samples have been examined with the help of Perkin Elmer-

TG/DTA instrument. From TG curves, it has been noted that weight loss of all four

explosive samples started near 165oC. Weight loss remained almost constant till 180

oC

but became rapid between 180-245oC due to thermal decomposition of TNT. Thermal

decomposition of all four samples over controlled temperature range of 180-245oC have

also found to be 86%. During brief investigation of TG curves, it has also been

observed that all the four samples undergo single stage reaction during thermal

decomposition.

(d)

Most compact and

smooth surface

115

Figure 5.7: TG Analysis of Chinese TNT Svc, Decanted TNT Unsvc,

TNT/15% Al and TNT/ 26% Al Samples


For thermal analysis of all four samples, DTA curves of Perkin Elmer-TG/DTA

instrument as shown in Figure 5.8 have been recorded. The results indicate that DTA

curves (heat flow curve) of Chinese TNT svc and decanted TNT Unsvc give two

distinct sharp peaks which are endothermic in nature. The 1st peak near 80+1

oC

corresponds to the melting of TNT samples which is in quite agreement with already

reported data [17-19]. Similarly, next endothermic peak around 240+5oC correspond to

thermal decomposition of TNT samples. However, in case of newly formulated blasting

explosive using decanted TNT/Al powder, small peaks prior to the melting of TNT

have also been observed which can be attributed to the melting point of paraffin wax

near 52oC. Since experiments were conducted in open atmosphere, therefore, slight

variations in thermal decomposition peaks for newly formulated blasting explosives

using decanted TNT/Al powder have been observed. It is also pertinent to mention that

decanted TNT unsvc sample melted earlier than Chinese TNT svc. However, thermal

decomposition phenomena took place later in decanted TNT unsvc as compared to

116

Chinese TNT svc. These slight variations in thermal behaviour may be linked to the

various types of impurities present in the decanted TNT unsvc sample. If we look at the

results of newly formulated blasting explosive using decanted TNT/Al powder, it can

be easily defined that both the samples started melting earlier than the rest of the two

samples. However their decomposition temperature occurred later than decanted TNT

and Chinese TNT samples. Interestingly, elevation of curves in case of newly

formulated blasting explosive using decanted TNT/Al powder on the heat flow axis

have been recorded that may be linked to the slow oxidation of Al metal which is an

exothermic process [20].

Figure 5.8: DTA of Chinese TNT Svc, Decanted TNT Unsvc,

TNT/15% Al and TNT/ 26% Al Samples


XRD analyses of all the four samples have been carried out for crystallographic studies.

Samples were scanned in the range of 20ᶿ to 43ᶿ angles and their XRD patterns are

shown in Figure 5.9. From XRD pattern, it can be deduced that there are four distinct

diffraction peaks available in case of Chinese TNT svc as well as for decanted TNT

unsvc samples. These peaks are very much similar to diffraction peaks present in XRD

117

pattern for pure TNT sample (as discussed earlier in chapter 3). However, in case of

newly formulated blasting explosives using decanted TNT/Al powder, additional

diffraction peaks for Al crystals have also been observed. Miller indices have been

marked on XRD peaks with h, k, l values of (004), (021), (-315) and (1021) for TNT

and (111) for Al crystals. The results from XRD pattern also reveals that TNT in all

crystalline states of four samples exist in monoclinic form and is considered more stable

than orthorhombic form which is metastable at room temperature [16]. It has also been

noticed that TNT samples belong to space group C2/c and space group number 15

which is in close agreement with literature data [21]. All four peaks with h, k, l value of

(004) seems to be more sharp and intense than the other recorded peaks. This intensity

shows higher value of TNT crystallinity as compared to other ingredients used in the

formulation processes. XRD pattern also exhibits that Al exist in cubic crystal system

with h, k, l value of (111) having space group Fm-3m and space group number 225.

Figure 5.9: XRD Pattern of Four Types of TNT Samples

118

5.5 Conclusion

After a brief investigation through various analytical techniques, it has been observed

that decanted TNT‟s unserviceable sample has lost some of the characteristics values

needed for military applications. Most noteworthy is the earlier decomposition of the

sample with lower activation energy (Ea). Existence of impurities is a prime factor for

degradation of explosives. Presence of any such impurities and defects in explosives

may lead to enhanced chances of premature ignition and an increase in the sensitivity of

explosives to shock and impact during storage and operations. It has been noted during

recent experimental work that the energy level of both the newly formulated TNT/Al

samples have increased due to the addition of Al particles. The same has also been

noted during DTA analysis of newly formulated samples where exothermic elevations

were observed. Amazingly, it has also been noticed that the presence of a multiple

number of pores and cracks in the microstructure of formulated TNT/Al samples have

been reduced to an appreciable limit. All these experiments for the formulation of new

TNT/Al samples have been quite successful and are considered appropriate for adoption

on a large scale. However, to improve further upon the safety aspects whilst handling

and formulating, it was considered best to eliminate Al and NC from the formulation

processes. For this purpose, a few more experiments were conducted in the present

research work and the same are discussed in Chapter 6.

119

References

[1] J.C. Pennington, J.M. Brannon, Thermochim. Acta 384 (2002) 163.

[2] J. M. Conder, T. W. La Point, J. A. Steevens, G. R. Lotufo, Environ. Toxicol.

Chem. 23, (2004) 141.

[3] X. Zhanga, Y. Lina, X. Shanb, Z. Chena, Chem. Eng. J. 158 (2010) 566.

[4] N. H. A van Ham, Waste Manage. 17 (1997) 147.

[5] S. D. Harvey, H. Galloway and A. Krupsha, J. Chromatogr. A 775 (1997) 117.

[6] J. Pichtel, Applied and Environmental Soil Science (2012) 1.

[7] M. E. Morgan, P. L. Miller, International Journal of Explosives and Chemical

Propulsion 4 (1997) 199.

[8] P. Wanninger, International Journal of Explosives and Chemical Propulsion 4

(1997) 155.

[9] O. Machacek , J. B. Gilion , G. Eck , J. Lipkin , R. Michalak , R. Perry, A.

McKenzie, L. Morgan, International Journal of Explosives and Chemical

Propulsion 4 (1997) 177.

[10] T. B. Brill, K. J. James, Chem. Rev 93 (1993) 2667.

[11] V. A. Babuk, V. A. Vassiliev, V. V. Sviridov, Combust. Sci. Technol. 163

(2001) 261.

[12] H. Ninga, L. Yudea, Z. Hongpengb, L. Chunpenga, International Symposium on

Safety Science and Engineering in China. Procedia Engineering 43 (2012) 449.

[13] Q. S. M. Kwok, R. C. Fouchard, A. M. Turcotte, P. D. Lightfoot, R. Bowes, D.

E. G. Jones, Propell. Explos. Pyrot. 27 (2002) 229.

[14] P. Brousseau, C. J. Anderson, 12th International Detonation Symposium, San

Diego, California (2002).

[15] N. J. Duijm, F. Markert, J. Hazard. Mater. A 90 (2002) 137.

[16] G. R. Miller, Naval Research Laboratory Washington, D.C., USA (2001).

[17] T. R. Gibbs, Alphonse P, LASL Energetic material Property Data. University of

California Press, L.A., USA (1980).

[18] O. Srihakulung and Y. Soongsumal, World Academy of Science, Engineering

and Technology 5 (2011) 739.

[19] S. Lixia, H. Rongzu, L. Jiamin, Thermochim. Acta. 253 (1995) 111.

120

[20] P. E. Snyder, H. Seltz, Carnegie Institute of Technology, Carnegie Mellon

University, USA (1945).

[21] Chongwei, J. Wang, W. Xu, F. Li, Propell. Explos. Pyrot. 35 (2010) 365.

[22] A. Maranda, J. Nowaczewski, A. Paplieski, Military University of Technology,

(2004), 361.

121

Chapter No. 6

Formulation of New Blasting Explosives Developed

from Decanted TNT and Suitable Ingredients


After going through various aspects of TNT/Al samples, it was decided to experiment

with a new formulation without the addition of Al and NC as both the chemicals have

proven very costly and sensitive in nature. Also, the resultant VODs of TNT/Al samples

are much greater than the VODs of normal blasting explosives available in the market.

Thus, an effort has been made to identify and use alternative oxidizers with decanted

TNT for the formulation of new blasting explosives. For this purpose, ammonium

nitrate (AN) and calcium ammonium nitrate (CaAN) have been selected and used in

different proportions with decanted TNT to formulate various blasting explosives.

Additionally, calcium carbonate (CaCO3), suitable wax and saw dust have been used as

stabilizers, anti-caking agents and additional fuels for the first time during the present

experimental work. Andrzej Maranda et. al., have already investigated the use of waste

TNT with AN in their research on the possible reuse of energetic materials for industrial

purposes [1]. However, in the current work, a different method has been used for the

possible reutilization of decanted TNT with AN. Additionally, to the best of our

knowledge, the use of CaAN as an alternative to AN has not been mentioned in the

available literature, thus, we have used it as the main oxidizer for the first time with

decanted TNT and the results proved remarkable! In this work, different samples have

been prepared in the laboratory using decanted TNT and other suitable ingredients.

Besides achieving additional safety in conversion, the aim was to formulate new

blasting explosives using decanted TNT with other suitable ingredients; while also

achieving cost effectiveness. Laboratory scale experiments have been conducted using

decanted TNT and other suitable ingredients. Furthermore, all the samples were tested

in the field and their ensuing results are described in detail in concerned sections of this

122

chapter. Once all the prerequisites of blasting explosives at laboratory scale had been

achieved, a pilot scale batch plant was designed, simulated and fabricated for the

formulation of blasting explosives developed from decanted TNT and other ingredients.

Real time experiments with decanted TNT and various essential ingredients have been

conducted through the pilot plant and all the samples have been tested in the field with

the help of a VOD meter and an Abel heat Test; along with the calculation of their

densities. The newly formulated blasting explosives developed from decanted TNT and

other ingredients are not only cheap but also very safe in handling and formulation. The

VOD results of all samples confirmed that the samples qualified on the basis of the

desired standards of commercial blasting explosives.

6.2 Laboratory Scale Formulations of Blasting Explosives

6.2.1 Materials Selection

All the ingredients utilized during the entire research work of this thesis have been

sourced locally to ensure timely availability and cost effectiveness. During laboratory

scale experiments, various ingredients mentioned in Table 6.1 have been used with

decanted TNT for the formulation of new blasting explosives. Different compositions

have been prepared during the present research work. It is evident from the resultant

data that altering the percentages of each composition, comprising of decanted TNT for

formulations of new blasting explosives, greatly affect the performance and overall

results. Interestingly, all the newly formulated blasting explosives developed in the

chemical laboratory have qualified upon the basic stability and VOD standards.

Moreover, the overall cost of final products (covered in Chapter 8) is remarkably less

than currently available products in the market.

123

Table 6.1: Compositions Used with Decanted TNT in Chemical Laboratory

Composition

No.

Composition

Name

Ingredients with %ages

Decanted

TNT CaAN AN CaCO3 Wax

Saw

Dust

3 (TAN) 7 - 88 0.5 0.5 4

4 (TCAN) 20 74 - 0.5 0.5 5

5 (TACAN-1) 30 30 30 0.5 0.5 9

6 (TACAN-2) 15 40 40 0.5 0.5 4

6.2.2 Procedure Adopted during Laboratory Scale Experiments

During the formulation of the entire compositions at laboratory scale proportions, a

similar procedure was adopted to ensure that the comparative analysis was conveniently

done and that there was no doubt appertaining to procedural changes. Pertinently, the

following steps have been taken during the formulation of new blasting explosives:

a. Measured quantity of the oxidizer was heated in a beaker kept in a water

bath and the material was stirred for a while.

b. Required quantity of decanted TNT was then added to the already heated

oxidizer and heated to sufficient temperature so that decanted TNT

remained in melted form during the entire formulation process.

c. Thereafter, a sufficient quantity of pre-melted wax was added to the

mixture and stirred continuously.

d. Finally, Chalk (CaCO3) was then mixed with the blend and mixture was

stirred continuously until homogeneous mixing was achieved.

e. Composition material was then allowed to cool down before a small

quantity of fine quality saw dust was sprinkled onto the composition.

f. The newly formulated explosive was sufficiently mixed through

continuous stirring before filling into suitable moulds such as plastic

tubes or polythene bags, etc.

124

Some of the safety gadgets used during explosives formulation processes are given in

Figure 6.1.

Figure 6.1: Safety Gadgets used During Explosives Formulation Process

6.2.3 Special Precautions Kept in Mind during Experiments

In this regard, the following precautionary measures have been ensured:

a. Formulations were carried out in such a way that heat was supplied

through indirect source to avoid contact between the material and the

heat source.

b. A hot water bath was used as heating source for the entire range of

experiments.

c. All electrical panels and connections were kept in isolation and away

from explosives to avoid generation of static charge.

d. Special gadgets including face mask, gloves, shoes and anti-static

laboratory coat were used during these experiments.

e. Experiments were carried out in isolation to keep all individuals and

materials away from any hazard or untoward situation during the

formulation process.

f. Waste materials were washed away immediately and collected using a

125

suitable tray.

g. Only a wooden stirrer was used during all laboratory experiments.

h. Newly formulated materials were preserved appropriately in an isolation

room ready for field testing through a VOD meter.

i. Additional experiments were performed using a fabricated plan. In this

regard, safety rules and regulations laid down for manufacturing of

explosives were thoroughly followed.

6.2.4 Abel Heat Test of Laboratory Formulated Blasting Explosive

Samples

In order to see the stability of all newly formulated blasting explosives at laboratory

scale, the Abel Heat Test was selected due to their simplicity and handiness. The Abel

Heat Test can be performed in any chemical or physical laboratory. It gives a fair idea

about the stability of a sample before its chemical or thermal degradation starts.

Results shown in Figure 6.2 reveals that all newly formulated blasting explosives

developed at laboratory scale are stable enough to sustain ordinary environmental

conditions. However, changes in compositions will automatically alter the state of

stability. During Abel Heat Tests, small quantities of all these newly formulated

blasting explosive samples were put in a beaker already filled with normal water. Water

temperature was raised to 81oC and then maintained at this temperature. Starch paper

(pre-dipped in a starch iodine solution) was then inserted into the beaker. Since iodine

solution immediately reacts with nitric fumes once exposed to them, any discolouration

of starch paper means that the degradation process has started. Commercial explosives

are considered stable enough if their degradation does not start before twenty minutes.

However, it is ideal that the samples must sustain beyond thirty minutes for prolonged

stability.

126

Figure 6.2: Results of Abel Heat Tests

6.2.5 Procedure Adopted for VOD Measurements

In order to obtain the VOD results for all newly formulated blasting explosives,

Explomet-fo-2000 VOD meter available in SCME have been used in the field firing

range. During the VOD measurements, the following steps are involved:

a. Arrangement for demolition stores including Tetryl CE, Electric/ Non

Electric Blasting Caps, Detonator holders, Dynamo Exploder, Crimper,

Anti-static Cutter, Safety Fuze, Flash Instantaneous Detonating (FID)

Cord, Match Fuze, Binding Tapes, Sand bags, Concrete Blocks, Digging

Tools, etc. Figure 6.3 shows the layout of some of the demolition stores

used during field tests.

TAN TCAN TANCAN-1 TANCAN-2

22

23

24

23

Decomposition Time (minutes)

127

Figure 6.3: Layout of Demolition Stores used During Field Tests

b. All these arrangements are necessary to complete the explosive train for

the initiation of the main explosive charge.

c. Coordination and arrangements for fire fighting personnel, medical aid

and various other administration groups to cater for emergency situations

during the disposal process.

d. Proper arrangements for warning signs and alarm systems to keep all

individuals and materials away from the demolition sites during the

ongoing procedure.

e. Clearance of the area before, and immediately after, the demolition

process.

f. Setting up of the VOD Meter and the fibre optical wires for clearance,

including the connectivity of all related connections in order to complete

the process of the VOD measurements.

g. Input of the required data pertaining to the sample into Explomet-fo-

2000 VOD meter before final measurements.

h. Once all procedures and SOPs are completed, the sample is initiated

through the blasting cap and the results are recorded in the

Explomet-fo-2000 VOD meter for use later on. Figure 6.4 gives a

128

general layout of the blasting explosive formulation till final disposal in

the field.

Figure 6.4: Stepwise Images of Blasting Explosives (Formulation till Final Disposal)

6.2.6 Field Tests of Laboratory Formulated Blasting Explosives using

VOD Meter

Field tests of all newly formulated blasting explosives including decanted TNT/Al

powder samples have been conducted using the VOD meter. The main purpose of the

VOD tests was to check the blast efficiency and field performance of newly formulated

samples. The VOD meter is a very effective and useful instrument available for the

measurement of VOD (m/s) of any particular material. It works as a digital counter for

129

measuring VOD up till 10km/s. It uses optical fiber probes that transmit emitted light

during the detonation of energetic material. The VOD meter clearly displays the power

and strength of any explosive. For present research work, the Explomet-fo-2000™

VOD Meter has been used for the VOD measurements of all samples. Before final tests

of all VOD samples were conducted, the VOD of Tetryl CE was measured through

VOD testing. Results were checked and verified with reference to literature data. Upon

confirmation of serviceability of the VOD Meter, proper VOD tests were conducted for

all newly formulated blasting explosives. The VOD meter results for different samples

are given in Figure 6.5.

Figure 6.5: VOD (m/s) Measurements of Different Samples including Decanted TNT

It has been noticed that all the newly formulated blasting explosives developed from

decanted TNT, along with other suitable ingredients, bear sufficient VODs. Since

commercial blasting explosives for rock blasting, mining and quarrying purposes

require materials having VOD greater than 2.5 km/s, it is determined that all of these

newly formulated samples can be effectively employed as blasting explosives for both

civil and military applications. Some of the measured results are displayed in Figure

6.6.

4929

5645

3601

2688 2624 2840 2617

VOD (m/s)

130

Figure 6.6: VOD (m/s) Results of Laboratory Formulated Blasting Explosives Samples

6.2.7 Density (g/cc) Calculation of Laboratory Formulated Blasting

Explosives

In the present research work, densities of all newly formulated samples along with

decanted TNT have been calculated using a simple measurement technique. The density

of each sample was calculated by putting a small quantity of the sample into a pre-

measured quantity of normal water poured into a graduated cylinder. Any change in the

volume was noted and recorded as the density of the sample. Calculated densities for all

samples including decanted TNT have been presented in Figure 6.7.

131

Figure 6.7: Density (g/cc) of Different Samples including Decanted TNT

6.3 Formulations of New Blasting Explosives though Pilot Plant and

Their Field Tests

As a mandatory part of the present PhD research work, a pilot scale plant was designed,

simulated and fabricated based on new blasting explosives developed from decanted

TNT. Further details about the plant are given in the subsequent chapter of this thesis.

Since all laboratory scale formulations have proved to be successful in giving positive

results about their VODs and densities, it was considered highly pertinent to translate

the laboratory scale compositions into useable blasting explosives through a pilot scale

plant. After successful completion of plant installation and functional trials, real time

experiments were conducted. In totality, 6 x different formulations of blasting

explosives were formulated using decanted TNT along with various other ingredients.

Approximately 6-8 kgs of each composition has been formulated through the pilot

plant. All of these 6x new blasting explosives have been verified through compulsory

field tests, i.e. VOD measurements, density calculations and stability tests through Abel

Heat tests. Subsequently, results of these tests are briefly explained below for each of

the 6 x samples.

6.3.1 Materials Selection

Although a large number of experiments have been conducted through the pilot plant,

1.47 1.43 1.392

0.95 0.85 0.81 0.84

Density (g/cc)

132

only 6 x types of compositions are being discussed here because the rest of the samples

were observed to bear almost similar results. Details of the 6 x different compositions

formulated through the pilot plant are mentioned in Table 6.2.

Table 6.2: Various Types of Compositions Used with Decanted TNT

Composition

No.

Composition

Name

Ingredients with %ages

Decanted

TNT CaAN CaCO3 Wax Saw Dust

7 TCAN-1 30 60 2 1 7

8 TCAN-2 25 70 1.5 0.5 3

9 TCAN-3 20 75 1.5 0.5 3

10 TCAN-4 40 50 1.5 0.5 8

11 TCAN-5 35 60 1.5 0.5 3

12 TCAN-6 25 65 1.5 0.5 8

6.3.2 Procedure Adopted During Real Time Experiments

Almost a similar procedure, as already discussed in the previous section of this chapter,

has been adopted during the formulation of all compositions through the pilot plant.

However, a few additional steps involved during real time experiments through the pilot

plant are appended below:

a. The water in the lower jacket of the plant is properly heated before the

operation starts.

b. Measured quantities of the selected oxidizer, i.e. CaAN or AN, is then

sufficiently heated in the plant from the heat produced by hot water

available in the lower jacket of the plant. Material is properly pressed

with the help of mashing rollers installed in the plant.

c. A sufficient quantity of decanted TNT is then added to the oxidizer and

the mixture is continuously mashed through rollers and a scrapper in the

plant.

d. Once the melted TNT properly impregnates on the oxidizers prills, pre-

measured quantity of wax is then added to the composition and the

133

operation continues until wax is properly coated onto the composition.

Wax acts as Phlegmetizer and also as anti-caking agent.

e. Finally, measured quantity of Chalk (CaCO3) is then added to the

composition to stabilize the sensitivity of decanted TNT. Composition is

allowed to mix continuously through the mashing roller and scrapper in

the plant until it is perfectly blended. Meanwhile, the temperature of the

plant is lowered to ambient levels.

f. Once the composition temperature reaches an ambient temperature, very

fine quality saw dust is sprinkled onto the composition in the plant and

the pressing through roller continues for a short while.

g. Composition once fully prepared is then poured into a desired mould for

further field tests, etc.

6.3.3 Stability Tests of New Blasting Explosive Formulated through

Pilot Plant

In line with already adopted procedure for stability of all newly formulated blasting

explosives through pilot scale plant, Abel Heat Test was selected. Since all samples

prepared to laboratory scale lack some stability, sufficient quantities of chalk were

added to all the samples formulated through pilot scale plant to make them more stable.

Figure 6.8 shows a brief account of results for all newly formulated blasting explosives.

Figure 6.8: Results of Abel Heat Tests

24

25

26

27

28

29

30

31

32

TCAN-1 TCAN-2 TCAN-3 TCAN-4 TCAN-5 TCAN-6

Decomposition Time (minutes)

28

32

27

31

28

29

134

Results shown in Figure 6.8 reveal that all newly formulated blasting explosives

developed through pilot plant are more stable than previously formulated samples at

laboratory scale. The main reason for enhanced stability may be attributed to an

increase in the percentage of chalk in all these formulations. Hence, all of these samples

can easily sustain normal environmental conditions. Furthermore, stability of all new

blasting explosives may be altered with changes in the percentages of the ingredients.

The results of all the samples are very satisfactory and it shows that the samples are

adequate enough to be accepted as commercial blasting explosives.

6.3.4 VOD Measurements of New Blasting Explosive Formulated

through Pilot Plant

Similar to all previous samples prepared at laboratory scale, the VOD measurements for

newly formulated blasting explosives have been carried out using the VOD meter.

Figure 6.9 shows the VOD results of all the newly formulated blasting explosives

developed from decanted TNT. The VOD tests were conducted on the Explomet-fo-

2000 VOD Meter. All the formulations have performed exceptionally well and

produced very promising and encouraging results. It has been noticed that the VODs for

all 6x newly formulated blasting explosives fall between 3409 m/s and 4335 m/s, which

makes them highly suitable for adoption as commercial blasting explosives.

Additionally, formulations of a wide range of new blasting explosives with different

compositions and varied VODs – i.e. higher and lower – are in hand. Thus, field

requirements for any kind of blasting explosive can be easily met through these

formulations.

135

Figure 6.9: VOD (m/s) Measurement of Newly Formulated Blasting Explosive

Developed from Decanted TNT through Pilot Plant

The VODs results of all new blasting explosives formulated through pilot plant are

given in Figure 6.10.

TCAN-1TCAN-2

TCAN-3TCAN-4

TCAN-5TCAN-6

3947 3807

4335

4000 3954

3409

VOD (m/s)

136

Figure 6.10: VOD (m/s) Results of all New Blasting Explosives Formulated through

Pilot Plant

137

6.3.5 Density (g/cc) Calculation of New Blasting Explosive Formulated

through Pilot Plant

Densities of all 6 x new formulations of blasting explosives have been calculated using

a simple measurement method (the detailed procedure has already been discussed in the

previous section of this chapter). Calculated densities for all 6 x newly formulated

samples have been presented in Figure 6.11.

Figure 6.11: Density (g/cc) of New Blasting Explosives Samples

including Decanted TNT

TCAN-1 TCAN-2 TCAN-3 TCAN-4 TCAN-5 TCAN-6

0.87

0.81

0.83

0.91

0.81

0.88

Density (g/cc)

138

6.4 Conclusion

In this work, multiple samples of new blasting explosives have been formulated using

decanted TNT and varied other ingredients. Initially, Al powder was used to experiment

with its effects on the new formulations. However, high cost, sensitive nature and

complicated handling make it an unsuitable candidate for ordinary blasting explosive

formulations. As an alternative, AN and CaAN have been used in subsequent

experiments and it has been observed that all the newly formulated samples using

decanted TNT, with either AN or CaAN, makes them most suitable oxidizers. Both, AN

and CaAN are relatively very cheap and insensitive during handling. Particularly, use of

CaAN as permanent oxidizer in next few samples formulated through indigenously

manufactured plant has given very promising results. CaAN is also very cheap, easily

available and has proven itself as a stable oxidizer due to which the overall cost of new

blasting explosives has been greatly reduced.

Reference

[1] Andrzej M., Jerzy N. and Andrzej P, Military University of Technology (2004)

361.

139

Chapter No. 7

Pilot Plant Design, Simulation and 3D Modeling

7.1 Summary of the Present Research

With the advancements in technologies, scientists and research around the world have

focused on modeling and simulation of various plants through suitable softwares.

Adoption of this mechanism has not only brought about a reasonable change in the

production cost of materials and chemical processing plant but also helped in finding

accurate results. Currently, a large numbers of simulation softwares are available in the

market. Researchers working in the field of explosives have also used variety of

simulation softwares for different tasks on explosives. Daniel O. Asante et al. (2015)

used Computational Fluid Dynamics (CFD) software package with the help of ANSYS

FLUENT for their research work on TNT. During their work, numerical CFD

simulation was carried out for the thermal behaviour of TNT including cook-off and

thermal decomposition [1]. The work done by M. Hobbs (2009) investigated the

convection and the non-convection effects of the detonation for confined explosives.

The COMSOL Multi-physics CFD tool was used during his simulation on TNT work

[2]. Similarly, L. Chen et al. (2010) carried out their simulation for the execution of fast

and slow cook-off behaviour in TNT explosives employing multiple heating rates [3].

The present research work is also based on the designing and simulation of pilot scale

plant for the formulation of new blasting explosives developed from decanted TNT.

Initially, Aspen HYSYS software was selected for design and simulation purpose.

However, the idea was replaced with Aspen PLUS®

simulation softwares as certain key

components were not available in Aspen HYSYS data base. Aspen PLUS® V8.4 being

most dynamic process simulator has thus been used for present design and simulation

work. Besides, PTC-Creo Parametric 3D Modeling Software has also been used for

modeling of the plant. A brief description of the research is given in succeeding

paragraphs.

140

7.2 Process Flow Diagram (PFD) of Pilot Plant

Process Flow Diagram (PFD) is a very simple and most effective way of demonstrating

common flow of chemical process. PFD is commonly used in chemical and process

engineering to facilitate in designing specific plant, its equipment and other major tools.

PFD broadly indicates the linkage between different parts and equipment of a chemical

plant. Thus before final simulation of pilot plant for decanted TNT through Aspen

PLUS® V8.4 simulation software, PFD or flow sheet was developed which is shown in

Figure 7.1.

Figure 7.1: Flow Sheet of Pilot Plant for Decanted TNT

7.2.1 Aspen PLUS® V8.4 Simulation Software

In the present research work, modeling and steady-state simulation of pilot plant for

reutilization of decanted TNT was carried out through Aspen PLUS®

V 8.4 simulation

software. Process simulation helps in evaluating the operating variable, optimization

and proper configuration in any design. In some of the process simulators few of the

modules are missing e.g. unit operation modules. In such a case, all missing details

regarding modules are manually added. However in modern simulators significant

toolboxes and unit operation modules are added as built in unit operations. Such an

addition not only saves time by doing very fast optimization of any process design but

is also considered easy to use and user friendly. Aspen PLUS® developed by Aspen

Technology, Inc. sufficiently assists in designing and simulating various forms of

141

chemical processes. During whole process of design and simulation, it is possible to

amend any specifications i.e. material composition, flow pattern and other working

conditions to suit the final design. In the present simulation work following

assumptions have been made to keep the steady-state simulation process easily

converged and to obtain the desired results in simple way:

a. Materials remained neutral as no chemical reaction took place between

different components and decanted TNT throughout the steady-state

simulation process.

b. Temperature of 90oC was kept for heater (H2) in case of decanted TNT

and 60oC for the other two heaters i.e (H1 and H3).

c. Ambient pressure of 1.013 bar was kept constant throughout the

simulation process and there was no pressure gradient.

d. Mass flow rate was set at kilogram/hour (kg/hr) for all components

including decanted TNT.

e. Maximum of 30 iterations were performed during steady-state

simulation process.

7.2.2 Steps involved During Simulation Process

During the conversion of complete decanted TNT reutilization process into Aspen

PLUS® V8.4 process simulation model, following steps were involved:

a. Components Selection

b. Global Selection

c. Properties Selection

d. Streams and Blocks Selection

e. Components Materials Characteristics

f. Heaters Characteristics

g. Mixers Characteristics

7.2.2.1 Components Selection

Before the start of simulation process, all chemical components involved in the

experimental work have been specified from the Aspen PLUS® V8.4 data bases. These

includes TNT, AN, CaCO3 and wax. Figure 7.2 displays various components specified

142

from Aspen Plus data bases.

Figure 7.2: Components Specified from Aspen PLUS® Data Bases

7.2.2.2 Global Selection

User defined unit set was selected so that all values obtained at the end are easily

interpreted and can be correlated with available data. Figure 7.3 shows selected set up

for steady-state simulation process.

Figure 7.3: Set up Selected for Steady-State Simulation Process

Similarly, SR-POLAR base method was selected for the simulation process. The main

143

reason for selection of SR- POLAR property method was that this method suits the

equation of states for highly non ideal systems. The Schwartzentruber-Renon is the

basis for the SR-POLAR property method. This method is effectively used for modeling

of chemically non-ideal systems [4-6]. Its accuracy is almost similar to that of activity

co-efficient property methods like WILSON property method. Figure 7.4 displays

SR-POLAR property method selected during steady state simulation process for the

present research work.

Figure 7.4: Selected SR-POLAR Property Method

After selection of appropriate thermodynamic model, flow sheet was configured using

physical properties of components and mixer. The batch type pilot plant for reutilization

of decanted TNT was deliberated with a total production capacity of 8-10 kg/ hr. For

present simulation process, mass flow rate of 8 kg/ hr of whole product have been

selected. Table 7.1 shows breakdown of mass flow rate (kg/hr) for each component

used in the present simulation.

144

Table 7.1: Mass Flow Rate of Various Components Per Batch

S. No Ingredients Flow rate/ batch in kg/hr

1 TNT 0.64

2 AN 7.20

3 CaCO3 0.08

4 Wax 0.08

Total product/ batch 8.00 kgs/hr

After specifying the basic data including thermodynamic conditions such as

temperature and pressure to be used in the simulation process, flow sheet was organized

which has previously been discussed in Figure 7.1.

7.2.2.3 Streams and Blocks Selection

Unless all the streams and blocks are completely defined, simulation process cannot

proceed. Thus it is very significant to specify all streams and blocks used in any process

simulation appropriately. In the present simulation process, all streams and blocks have

been specified with requisite inputs. Figure 7.5 and Figure 7.6 shows various streams

and blocks used in present simulation process, respectively.

Figure 7.5: Streams Specified in Simulation Process

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Figure 7.6: Blocks Specified in Simulation Process

Results obtained after simulation process for each stream and block have been deduced

which will be discussed in succeeding paragraphs.

7.2.2.4 Component Materials Characteristics

For the present simulation work, different component materials used in real laboratory

work have been selected. All the component materials have been enlisted in Table 7.2

along with required input details and other characteristic values.

Table 7.2: Components with their Characteristic Values

S. No Component

Temperature (oC) Pressure

(bar)

Mass Flow

rate (kg/hr) Initial Final

1 TNT 25 90 1.013 0.64

2 AN 25 60 1.013 7.20

3 CaCO3 25 25 1.013 0.08

4 Wax 25 60 1.013 0.08

Figure 7.7 (a), (b), (c) and (d) shows all components with their characteristic values

specified in Aspen PLUS® simulation process.

146

(a)

(b)

147

Figure 7.7 (a), (b), (c) and (d): Components with Characteristic Values used in

Simulation Process

7.2.2.5 Heaters Characteristics

In order to provide sufficient heat to certain component materials during simulation

process, three (3) heaters with varying conditions have been used in the present

(d)

(c)

148

simulation process. Table 7.3 shows heaters with specified condition and their uses.

Ambient pressure (1.013 bar) was kept constant throughout the simulation process.

Figure 7.8 (a), (b) and (c) represents all heaters with their specified input values.

Table 7.3: Heaters with Specified Conditions Used in Simulation

S.

No Heater ID Used with Valid Phase

Temperature

(oC)

Stream

1 H1 AN Solid 60 S1

2 H2 TNT Liquid 90 S2

3 H3 Wax Liquid 60 S3

(a)

149

Figure 7.8 (a), (b) and (c): Different Heaters with their Input Values used in

Simulation

7.2.2.6 Mixers Characteristics

Unlike chemical plants where chemical reaction takes place during mixing formulation,

no such chemical reaction is expected during formulation of decanted TNT with

oxidizer and other components. Thus, any chances of pressure build up or accumulation

(b)

(c)

150

of gaseous product inside plant is least expected. Secondly provision of fume

discharging unit in case of real fabricated plant also minimizes any chance of pressure

build etc. Simple mixer was selected for the present simulation work with expected

temperature of around 85oC inside the plant. Figure 7.9 shows input values of mixer

Figure 7.9: Mixers with Input Values used in Simulation Process

7.3 Simulation Results

Once all the input values regarding each component, stream and block were completed

successfully, simulation was run. It has been learnt that the process simulation has

converged successfully and results have been displayed in separate excel sheet. Values

for the entire simulation have been given in Table 7.4. It has been noticed that the final

product has a density of 1.704 g/cc. Total mass flow of the product during process

simulation remained 8.0 kg/hr. Although, maximum temperature of 90oC was supplied

during input data but simulation results shows temperature of the final product as

94.3oC.This rise in temperature of the final product may be linked to accumulation of

heat inside the plant which has ultimately raised the internal temperature of the final

product. Pressure of 1.013 bar remained constant throughout simulation and no pressure

gradient has been observed from resultant data. Average MW of the final product is

calculated as 85.26. Remaining minor details (self-explanatory) obtained as excel sheet

are shown in Table 7.4.

151

Table 7.4: Simulation Results obtained through Aspen PLUS® V8.4 Software

Heat and Material Balance Table

Steam ID - AN CaCO3 FP S1 S2 S3 TNT Wax

From - - - MX H1 H2 H3 - -

To - H1 MX - MX MX MX H2 H3

Phase - LIQ LIQ SOLID SOLID LIQ LIQ LIQ LIQ

Substream:

MIXED - - - - - - - - -

Mole Flow kmol/hr - - - - - - - -

TNT - 0.0 0.0 .81E-3 0.0 .81E-3 0.0 .81E-3 0.0

AN - .0899 0.0 .089 0.089 0.0 0.0 0.0 0.0

CHALK - 40.0 .99E-4 .99E-4 0.0 0.0 0.0 0.0 0.0

WAX - 0.0 0.0 .57E-4 0.0 0.0 .57E-4 0.0 .57E-4

Total Flow kg/h 7.20 .08 8.0 7.20 0.64 .08 .64 .08

Temperature C 25.0 25.0 94.30 60.0 90.0 60.0 25.0 25.0

Pressure bar 1.013 1.013 1.013 1.013 1.013 1.013 1.013 1.013

Density g/cc .267 .334 1.70 1.72 1.066 .542 1.094 .549

Average MW - 80.04 100.0 85.26 80.04 227.13 310.60 227.13 310.60

7.4 3D Model of Decanted TNT Reutilization Plant

Pilot plant fabrication requires brief model and accurate specifications before

undertaking fabrication work. For the fabrication of present plant for reutilization of

decanted TNT, detailed paper work and funds allocation was required. Once all the

formalities were finalized, 3D model of pilot scale plant was created through PTC-Creo

Parametric 3D Modeling Software. This software is quite dynamic in its application

having powerful and flexible 3D CAD capabilities.

Some of the key features of PTC-Creo Parametric 3D Modeling Software are:

a. Creation of 3D models of any part or assembly in very fast time and in

comfortable way.

b. It helps in creating different designs automatically giving full reliabilities

and confidence.

c. It has both features of parametric and direct modeling.

d. Enhance design aesthetics with broad surfacing power.

152

e. Easy accessibility to brief learning materials and manuals for user

benefits.

Figure 7.10 shows 3D model created on PTC-Creo Parametric 3D Modeling Software

for re-utilization of decanted TNT.

Figure 7.10: 3D Model of Decanted TNT Re-utilization Plant

7.5 Conclusion

With the advent of new technologies and latest softwares, it is relatively easy to design

and fabricate a production facility for any composition. However, a great deal of effort

and dedication are required to translate theoretical knowledge into practical application.

The use of most advanced softwares like the Aspen PLUS® process simulator and the

PTC-Creo Parametric 3D Modeling Software have helped in achieving the desired

model for the formulation of new blasting explosive using decanted TNT. Simulation

results also enabled us to investigate and predict possible production costs of the plant

and materials. Through these results, it has been possible to fabricate and install pilot

scale plant at SCME, NUST during the course of present research work.

153

References

[1] D. O. Asante, S. Kim, J. Chae, H. Kim, M. Oh, Propellants Explos. Pyrotech. 40

(2015) 699.

[2] M. Hobbs, Society for Experimental Mechanics Inc. USA. (2009).

[3] L. Chen, C. Wang, X. Ma, F. Wang, Workshop on Energetics, Hong Kong

(2010).

[4] G. Soave, Chem. Eng. Sci. 27 (1972) 1196.

[5] J. Schwartzentruber, H. Renon, Ind. Eng. Chem. Res. 28 (1989) 1049.

[6] A. Peneloux, E. Rauzy, R. Freze, Fluid Phase Eq. 28 (1982) 7.

154

Chapter No. 8

Pilot Plant Fabrication, New Blasting Explosives

Analyses, General Conclusion and Suggestions for

Future Work


During previous chapters of this thesis, various phases of research work, including

materials management, sample preparation, characterization and related aspects, have

been discussed at length. The aim of the present research work is to build a platform for

the successful reutilization of unwanted explosive, i.e. decanted TNT into blasting

explosives. The Pakistan army, being one of the largest armies of the World, maintains

large stockpiles of munitions containing both serviceable and unserviceable lots.

Although, a great deal of effort has been made in the past to safely discard these

munitions, there is still a dire need to arrange an alternate solution for the disposal of

unwanted munitions. In the present research work, decanted TNT has been reutilized in

combination with other suitable ingredients to formulate new blasting explosives which

can be used in civil and military applications like mining, quarrying and rock blasting,

digging trenches, demolitions, etc. In order to accomplish the last part of the present

research work, a pilot scale plant has been designed, simulated and fabricated; whereby

useful blasting explosives are formulated on this plant. Details regarding the fabrication

of the plant, safety aspects of the plant and cost analyses of both commercially available

products vis-a-vis these products have been discussed in detail in this chapter. Lastly, a

few general conclusions and suggestions have been given for future research work.

155

8.2 Pilot Plant Fabrication

In order to complete the current research work, a process flow diagram was made and

thereafter, the process of designing, simulation and fabrication was carried out.

Adequate measures were taken to ensure that all safety aspects were completed before

finalization of the fabrication work. The structure of the batch type plant is made of

mild steel and it has a production capacity of 8-10 kg/ batch in an hour. This plant was

installed in the Chemical Engineering Department of SCME, NUST and its functional

tests were conducted using non-explosives materials to ensure safety during the plant‟s

trial stage. After successful installation, real experiments were conducted using

decanted TNT and various other ingredients to formulate new blasting explosives.

Figure 8.1 shows the pilot plant fabricated and installed at SCME, NUST for the

production of new blasting explosives using decanted TNT and various other

ingredients. Figure 8.2 demonstrates plant room constructed for accommodation of the

pilot plant.

Figure 8.1: Pilot Plant Fabricated and Installed for New Blasting Explosives

156

Figure 8.2: Plant Room Constructed for Formulation of New Blasting Explosives

8.2.1 Components of Pilot Plant

Pilot plant mainly composed of following components:

a. Double jacketed mixing drums with 1m diameter and approximately18

inches height for mixing of ingredients. Hot water rotates in the lower

drum and provides sufficient heat to the mixer components.

b. Meshing roller with angular mixing blade for homogeneous mixing of

decanted TNT and other ingredients.

c. 5 Horse Power (HP) electric motor with RPM control mechanism

(installed outside plant room).

d. Vertical gear box with rotary mechanism.

e. Fume discharging unit.

f. Heat source (coiled band heater).

g. Water pipes for hot and cold water supply.

h. Outlet vent or hoper for removal of final product.

In Figure 8.3, pilot plant along with newly formulated blasting explosives samples

157

developed from decanted TNT as well as decanted shells have been given.

Figure 8.3: Pilot Plant with Newly Formulated Blasting Explosives

and Decanted Shells

8.2.2 Technical Data of Pilot Plant

Some of the main features of fabricated plant are appended below:

a. Capacity - ~8 to 10 kg/ batch

b. Time required per batch - ~1 hour

c. Operating temperature in lower jacket - 90oC

d. Decanted TNT melting temperature - ~81 oC [1-2]

e. Operating pressure - 1.013 bar

f. Electric motor power - 5 HP (3-phase)

g. Maximum men limit - 3

(1 technical staff, 2 labours)

h. Fabrication and installation cost (in PKR) - 0.625 million

(including General Sales Tax)

8.3 General Hazards involved During Formulation of Explosives

Explosives are highly sensitive compositions as compared to common organic

compounds. Extra precautionary measures, safety and care are required during

158

formulation, handling, transportation and storage conditions. It is therefore extremely

important to cater for all kind of associated hazards involved with explosives. Some of

the notable hazards involved during formulation of explosives are listed below:

a. Creation of excessive heat and pressure during ingredient mixing and

formulation of decanted TNT and other ingredients.

b. Production of fumes and gases during mixing and processing of different

ingredients with decanted TNT.

c. Initiation of electric spark and flash from electric panels and

switchboards.

d. Spilling of explosives and other ingredients on the sides of reutilization

plant or on floor surface during materials pouring and mixing and

extraction.

8.4 Safety Precautions Taken During Blasting Explosives

Formulations

Strict adherence to the Standard Operating Procedures (SOPs) on safety of explosives is

mandatory as explosives are very sensitive and extremely precarious if roughly handled.

In the present research work all possible safety precautions have been ensured to cater

for any chance of accidents and hazards. Some of the major safety measures adopted

during processing of decanted TNT with other ingredients are listed below:

a. Open space between building and roof top for clear discharge of fumes

and gases.

b. Plant room has been designed in such a way to allow immediate escape

of accumulated pressure through the roof to avoid extreme damage to

surrounding environment and building.

c. Use of fume discharging unit at the top also helps in safe discharge of

fumes and toxic gases.

d. Heating of decanted TNT and other composition through hot water flow

in the lower jacket of the pilot scale plant. Thus avoiding direct heating

of explosive materials through electric source which may ignite the

composition through spark or flash.

159

e. Use of protection wall inside plant room to ensure extra safety during

explosives formulation.

f. Arrangement for protection/ safety screens to ensure remote observation

during explosives processing.

g. Complete checking and inspection of explosive-proof electric switches

and other equipment before processing of explosives.

h. Use of heat and fire resistant bricks in plant room floor for heat and fire

resistance.

i. Use of hot and cold water supply to the pilot scale reutilization plant.

j. Use of water supply for immediate washing and removal of spilled

explosives or other ingredients on floor surface.

k. Plant room has been constructed in such a way that sun light is directly

available during working hours and there is no requirement for

additional electric source of light (conduit wiring, bulbs, etc.).

l. All electric appliances have been kept outside plant room to deny

accessibility of any spark and light to the reutilization plant.

m. Limited quantity of explosives is processed batch wise to facilitate safety

and security.

n. Arrangement for recycling of waste water after circulation.

o. Special care and attention during mixing and formulation.

p. Regular monitoring through cameras fitted inside plant room.

q. Plant room is constructed in isolation to keep all men and materials away

from any untoward incident.

r. Only minimum allowed men are given access to the plant room and none

other is allowed to visit the facility.

s. Outside walls and structure including main entrance gate of explosives

field testing area are made strong enough to sustain any kind of blast and

fire.

t. Strict adherence to working time is ensured and no one is allowed access

thereafter.

160

u. In order to avoid accumulation of static charge, lighting conductors have

been installed in the plant room and its serviceability is ensured through

regular check and monitoring.

v. Use of protection clothes, helmet, gloves and glasses by the technical

staff during working environment has been ensured.

w. Copper scrubbers have been arranged for scrapping of explosives from

plant surfaces.

x. Use of automatic discharge fire extinguishers and auto fire extinguisher

balls in plant room.

8.5 Cost Analysis (Commercial Vs New Blasting Explosives)

Explosives are used according to their characteristics and power. Similarly their costs

are estimated as per their utilities and shelf life. All military and commercial grade

explosives are required to be cost effective to save economy. In the present research

work, efforts have been made to formulate very cheap and cost effective blasting

explosives using decanted TNT and other ingredients. Estimated costs of these newly

formulated blasting explosives have been compared with commercially available

products (blasting explosives) to see the difference in cost.

8.5.1 Commercial Products (Blasting Explosives) and their

Characteristics

Commercially available blasting explosives are used by both civil and military

organizations for their mining, quarrying, road construction, underwater blasting, etc.

Almost all types of commercial explosives are utilized in various defense and civil

industries. Latest costs (in Pakistan currency, Rupees) of various commercial explosives

provided by two major industries in Pakistan are available. However, these are

estimated costs and may vary to some extent. Table 8.1 gives costs of some of the

locally available commercial explosives.

161

Table 8.1: Cost of Some of the Commercial Explosives Available in Pakistan with

VOD (m/s)

S. No Product

Name

Density

(g/cc)

VoD

(m/s)

Rate in PKR

per kg Consistency Company

1 Wabox 1.5±.10 5000 460.00+20 Gelatinous

#WAH

NOBEL

Pakistan

2 Wabox

80% 1.45±.10 5000 450.00+20 Gelatinous

3 Wabox

60% 1.40±.10 3000 445.00+20 Gelatinous

4 Wabox

40% 1.40±.10 2500 390.00+20 Gelatinous

5 Wabofite 1.0±.05 3000 325.00+20 Semi

Gelatinous

6 Wabonite 0.90±.05 2500 260.00+20 Powder

7 Wapril 0.75±.03 2500 260.00+20 Powder

8 BIO-

BULK 0.88±.04 9185 360.00+20 Gelatinous *BIAFO

Industries

Pakistan 9 BIO

PRIL 0.85±.04 8202 260.00+20 Powder

Source: #http://www.wahnobel.com/index.php, *http://www.biafo.com/index.html

8.5.2 New Blasting Explosives Formulated in Laboratory and their

Characteristics

For the present research work, decanted TNT was arranged through defense

organization, whereas other ingredients were purchased from local market to formulate

new blasting explosives. Both analytical and commercial grades chemical materials

were used during experimental work to suit the explosive nature and final cost of the

new blasting explosives. Table 8.2 shows cost analysis of newly formulated blasting

explosives.

http://www.wahnobel.com/index.php

http://www.biafo.com/index.html

162

Table 8.2: Cost (in PKR) of New Blasting Explosives Formulated in Laboratory with

their Densities (g/cc) and VODs (m/s)

S.

No

Product

Name

Density

(g/cc)

VOD

(m/s)

Rate in

PKR per

kg

Consistency Company

1 TAL-1 1.43±.10 5645±5.6 200.00+20 Solid

Composite

SCME,

NUST

Pakistan

2 TAL-2 1.392±.10 3601±3.6 195.00+20 Solid

Composite

3 TAN 0.95±.05 2840±2.8 100.00+20 Powder

4 TCAN-1 0.85±.05 2617±2.6 100.00+20 Powder

5 TCAN-2 0.80±.05 2688±2.6 100.00+20 Powder

Estimated costs of the entire ranges of newly formulated blasting explosive have been

calculated. However, there may be some variation in cost of the product depending on

large scale production, changes in percentages of different ingredients and other

associated factors.

8.5.3 Comparative Analyses of Commercial Vs Laboratory

Formulated New Blasting Explosives

In order to qualify for the required standard, comparative analyses of newly formulated

blasting explosives have been carried out with commercially available products having

almost similar characteristics. Since all the samples produced during this research work

have qualified the basic criteria for blasting explosives, therefore, final comparison

between new blasting explosives vis-a-vis commercial products have been recorded.

Mainly comparisons have been drawn in two major categories i.e. VOD (m/s) and Cost

(in PKR) for commercial explosives vs new blasting explosives. VOD comparison

graph is shown in Figure 8.4.

163

Figure 8.4: Graph Showing Comparative Analysis of VOD (m/s) for Commercial

Explosives Vs New Blasting Explosives

Similarly compasrison of the cost in Pakistan currency have been drawn for both the

commercial products vs new blasting explosives. It has been noticed that almost all the

newly formulated blasting explosives are very cheap and bear minimum cost in

comparison to the available commercial products. Cost analysis of both the categories

of products has been displayed in graphical form as shown in Figure 8.5.

164

Figure 8.5: Graph Showing Comparative Analysis of Cost (in PKR) for Commercial

Explosives Vs New Blasting Explosives

To further elaborate upon the cost analysis, comparative analyses of both commercial

products and new blasting explosives is given in table 8.3.

Table 8.3: Comparative Analysis of Cost (in PKR) of Commercial Explosives Vs New

Blasting Explosives Formulated in Laboratory

S.No Commercial

Explosives

Cost per

kg

New Blasting

Explosive Cost per kg

Difference in

Cost (PKR)

1 Wabox 460.00±20 TAL-1 375.00±20 85.00±20

2 Wabox 80% 445.00±20 TAL-2 290.00±20 155.00±20

3 Wabonite 260.00±20 TAN 110.00±20 150.00±20

4 Wabox 40% 390.00±20 TCAN 110.00±20 290.00±20

5 Wabofite 325.00±20 TACAN-1 100.00±20 225.00±20

6 Wapril 260.00±20 TACAN-2 100.00±20 160.00±20

165

8.5.4 Newly Formulated Blasting Explosives using Pilot Plant with

their Characteristics

After successful installation of pilot plant multiple samples were formulated using

decanted TNT and different ingredients. Approximated cost for all newly formulated

blasting explosives have been calculated based on the current market rates including

labour and energy costs. Final cost of each type of sample was estimated at an average

of Rs. 120/ kg as almost all the formulations bears similar ingredients. Details of each

type of formulation with characteristic values are given in Table 8.4.

Table 8.4: Cost of New Blasting Explosives Formulated using Pilot Plant with their

Calculated Densities (g/cc) and VODs (m/s)

S.No Commercial

Product

Density

(g/cc)

VoD

(m/s)

Rate in

PKR per

kg

Consistency Company

1 TCAN-1 0.87±.05 3947±3.9 120.00±20 Powder

SCME,

NUST

Pakistan

2 TCAN-2 0.81±.05 3807±3.8 120.00±20 Powder

3 TCAN-3 0.83±.05 4335±4.3 120.00±20 Powder

4 TCAN-4 0.91±.05 4000±4.0 120.00±20 Powder

5 TCAN-5 0.81±.05 3954±3.9 120.00±20 Powder

6 TCAN-6 0.88±.05 3409±3.4 120.00±20 Powder

Comparative analysis of the costs for both commercial products as well as new blasting

explosives formulated through pilot plant is given in Table 8.5.

166

Table 8.5: Comparative Analysis of Cost (in PKR) of Commercial Explosives Vs New

Blasting Explosives Formulated using Pilot Plant

S. No Commercial

Product

Cost per

kg

New Blasting

Explosive

Cost per

kg

Difference in

Cost (PKR)

1 Wabox 460.00±20 TCAN-3 120.00±20 340.00±20

2 Wabox

80% 445.00±20 TCAN-4 120.00±20 325.00±20

3 Wabonite 260.00±20 TCAN-2 120.00±20 140.00±20

4 Wabox

60% 430.00±20 TCAN-5 120.00±20 310.00±20

5 Wabofite 325.00±20 TCAN-1 120.00±20 205.00±20

6 Wapril 260.00±20 TCAN-6 120.00±20 140.00±20

Since, laboratory scale experiments have been translated into real time products

formulated through pilot plant, thus comparison of both VODs and costs for all new

blasting explosive formulated through pilot plant have been displayed in graphical

form. VOD comparison graph is shown in Figure 8.6.

Figure 8.6: Graph Showing Comparison of VOD (m/s) for Commercial Explosives Vs

New Blasting Explosives

167

In line with laboratory scale formulated new blasting explosives, all the samples

formulated through pilot plant have proved to be very cost effective and economical as

their rates are almost 1/3rd

of the available commercial products having similar VOD

and other specifications. Cost analysis has been shown in graphical form which is given

in Figure 8.7.

Figure 8.7: Graph Showing Cost Analysis of Commercial Explosives Vs New

Blasting Explosives Formulated through Pilot Plant

8.6 Estimation of Timeline Required for Cost Recovery of Industrial

Scale Batch Plant (Approximately 300 kg)

The existing pilot plant has a capacity of about 8-10 kg/ hour per batch. It has a total

cost of Rs. 0.625 million. Since, this plant was a part of PhD research work whereby

additional cost on research and development, trials and installations has incurred.

However, in case of industrial scale batch plant with a total capacity of about 300 kg/ hr

per batch, the total cost may be estimated at Rs. 7.0 million. This cost may be earned

back through savings from product sale in about one year time.

168

Following details will further clarify the plant estimates:-

a. Average Per kg saving of blasting explosives - Rs. 150/-

b. Per 300 kg saving of blasting explosives - Rs. 45,000/

(on daily basis)

c. Per Month saving of blasting explosive - Rs. 7,20,000/-

(planned on 4 x working days a week)

d. No of Months required to complete the cost - 10 months

e. Total Cost in 10 months x Rs.7,20,000/-) - Rs.70,20,000/

Rs.7.02 Million

Note: These are estimated calculations based on current difference between the cost of

commercial products and new blasting explosives developed from decanted TNT.

These estimated data may vary to a great extent once practically applied. However, as a

guideline industrial plant with a minimum operating life of 10 years, it may help save

about Rs. 60.00 million to the government exchequer.

8.7 Conclusion

Various aspects of the pilot plant have been discussed briefly in this chapter. The most

prominent feature is the pilot plant fabrication for the safe reutilization of decanted

TNT into new blasting explosives. Other main highlights are the technical data

pertaining to the plant, its main components, and safety in explosives formulation

procedures. Moreover, this chapter broadly covers the VODs and cost analyses of both

commercially available blasting explosives vis-à-vis newly formulated blasting

explosives, containing both laboratory scale formulations and also formulations through

pilot plant. It has been learnt after comparative analysis that almost all the formulations

carried out in the present research work are not only viable for use as blasting

explosives in both military and commercial applications but also very cheap and cost

effective. All the samples formulated in the present work meet the requirements of

blasting explosives and their ingredients can be easily altered to suit other requirements.

Additionally, all the ingredients used in the formulation of the present samples utilizing

decanted TNT are easily available in the local market. The fabricated plant can also be

maintained effortlessly through local market and all parts and accessories are available.

169

General Conclusion

Explosives are categorized as one of the most sensitive and highly energetic materials.

A great deal of respect and care during handling, formulation, transportation and during

storage conditions is demanded by these high explosives. Previously, all these precious

commodities were disposed of through conventional disposal techniques such as

OB/OD, incineration, sea dumping, demolition, etc. However, in the present research

work, the aim was to successfully reutilize unserviceable TNT into blasting type

explosives. During the initial stages of the research work, decanted TNT was used with

Al powder in measured quantity to formulate new blasting explosives. Al is highly

exothermic in nature and relatively very sensitive while handling in experiments with

high explosives, therefore, as an alternate, AN and CaAN have been used in subsequent

blasting explosives formulations. All these newly formulated samples, including Al

based formulations, were subjected to thermal cum kinetic evaluation to determine

various thermal, chemical and morphological characteristics. In addition to this, the

stability, density and VOD tests have been conducted for all new blasting explosives.

Subsequently, a pilot scale plant has been designed, simulated and fabricated during the

present research work. Multiple experiments were conducted for the formulation of new

blasting explosives developed from decanted TNT and suitable ingredients. Lastly,

comparative cost and VOD analyses of all the newly formulated blasting explosive

samples were carried out with commercially available products to determine the

comparative difference. Fortunately, in cost vis-à-vis effectiveness, almost the entire

ranges of new blasting explosive samples have achieved an economical edge over the

commercially available products. Through this project, Pak-EPA‟s concerns about

environmental pollution regarding disposal techniques will be addressed. In addition to

this, the current research holds the potential honour of increasing Pakistan’s Carbon

Credit Rating around the globe!

170

Suggestions for Future Work

The suggestions based on the extant research work are as follows:

a. Research work carried out at pilot scale to be translated into industrial scale for

commercialization so that optimum utilization of available unwanted munition

is carried out.

b. PhD research to be initiated on various other explosives such as RDX, HMX,

etc. to cope with the requirement of safe handling of these unwanted munitions.

design of pilot plant based on new blasting explosives

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