A

Practical Training Report

On

“Hindustan Zinc Limited”

Submitted

in partial fulfillment for the award of the degree of

Bachelor of Technology

In Mechanical Engineering

Submitted to: Submitted by: D N Naresh Gagandeep Singh (HOD, ME) B.Tech VII Sem 09EJEME019

Department Of Mechanical Engineering

Jaipur Engineering College, Kukas

Rajasthan Technical University

2012-2013

ACKNOWLEDGEMENT

Only until you've climbed the mountain can you look behind you and see the vast distance that you've covered, and remember those you've met along the way who made your track a little easier . Now that this book is finally finished after the many miles of weary travel, I look back to those who helped me turn it into a reality and offer my heartfelt thanks:

To my lecturers , friends and employees of CSC for their contribution in completing of my training and preparation of project report successfully.

A heartful thanks to the following people,

NAME LOCATION

Mr. N.K.Vyas Head Mechanical Engineering

Mr. M.S. Khan Sinter

Mr. Kailash Chahande ISF

Mr. Krishna Reddy Lead Ckt

Mr. Rajesh Verma Auto garage

Mr. R. Bhujanga Rao Mechanical Workshop

A special valuable asset was the expect lecture delivered by all those engineers who are working in the plant control room.

I am also grateful to safety department for the safety training that helped me to get safe in the plant.

I am grateful to HR department for the assistance they provided me for my training.

I would also like to thank Mr. D N Naresh (HOD-Mechanical) JEC, Kukas and all the faculty members of Mechanical Engineering Department for their effort of constant co- operation, which have been a significant factor in the accomplishment of my industrial training.

Gagandeep Singh

PREFACE

The practical training is an essential requirement for an engineering student. The student has to take the training for the pre-described period as per the university norms. The purpose of training is to help the student to gain industrial experience. Moreover, as for the utility of training concerning, it can be said that student gets an opportunity during his training to imply the theoretical knowledge in the field work and to clear the difficulties in a better way.

In the year 2012, after completion of 6th semester, I took my training at Chanderiya Smelting Complex, known as CSC, a unit of M/s Hindustan Zinc Limited of ' VEDANTA RESOURCES ' group.

TABLE OF CONTENTS

TOPICS Page No.

1. INTRODUCTION............................................................

2. SAFETY DEPARTMENT................................................

3. SINTER PLANT...............................................................

4. IMPERIAL SMELTING FURNACE...............................

5. LEAD Ckt GROUP...........................................................

6. AUTO GARAGE..............................................................

7. MECHANICAL WORKSHOP.........................................

8. CONCLUSION.................................................................

INTRODUCTION

Hindustan Zinc Limited:

Hindustan Zinc is a Vedanta Group company in Zinc, Lead and Silver business. It is India's

only and the world's largest integrated producer of Zinc-Lead. Also being one of the leading

Silver producers in the world. HZL’s business comprises of mining and smelting of zinc and

lead along with captive power generation. There are four mines and four smelting operations:

mines are situated at Rampura Agucha (largest zinc producing mine in the world), Sindesar

Khurd, Rajpura Dariba and Zawar in the State of Rajasthan; while the smelters are located at

Chanderiya, Debari and Dariba in the State of Rajasthan and Vizag in the State of Andhra

Pradesh.

The current metal production capacity is 1,064,000 tonnes per annum (879,000 tonnes of zinc

and 185,000 tonnes of lead). With reserves and resources of 313.2 million tonnes, HZL’s

exploration programme is integral to its growth and future expansions. Successful exploration

and subsequent development of mineral assets underlines the mission and business strategy.

HZL also owns a 474 MW of coal based thermal captive power plants in Rajasthan to support

the metallurgical operations. It also has 123.2 MW of wind energy in Gujarat and Karnataka,

which is sold to the respective State grids.

HZL Operations (Mines)

HZL Operations (Smelters and Wind Power Plants)

Highlights of HZL:

The only fully integrated Zinc-Lead producer in the country

Having three lead-zinc mines, three smelters in Rajasthan and one at Vizag, Andhra

Pradesh.

Annual turnover of Rs.11,405 crores with a PBDIT of 6454 crores for the year 2011-

12

Strive for continuous improvements in Environment, Health, Safety performance of

its operations

Stimulating working atmosphere

Galvanizing India’s growth

Refined Zinc production capacity – 879000 TPA

Refined Lead production capacity – 93,000 TPA

Ore production capacity – 9.75 MTPA

Talent pool of over 7,000 employees.

Continuous operational improvements, meticulous planning, constant innovation,

debottlenecking, continuous process improvements, extensive R & D, technological up

gradation and so much more – HZL has come a long way and grown into a multi-unit and

multi-product company.

PHYSICAL AND CHEMICAL PROPERTIES OF ZINC:

Atomic number 30

Atomic mass 65.37 g.mol -1

Electronegativity according to Pauling 1.6

Density 7.11 g.cm-3 at 20°C

Melting point 420 °C

Boiling point 907 °C

Vanderwaals radius  0.138 nm

Ionic radius 0.074 nm (+2)

Isotopes 10

Electronic shell  [ Ar ] 3d10 4s2

Energy of first ionisation 904.5 kJ.mol -1

Energy of second ionisation 1723 kJ.mol -1

Standard potential - 0.763 V

Discovered Andreas Marggraf in 1746

Zinc is a lustrous bluish-white metal. It is found in group IIb of the periodic table. It is brittle and crystalline at ordinary temperatures, but it becomes ductile and malleable when heated between 110°C and 150°C. It is a fairly

reactive metal that will combine with oxygen and other non-metals, and will react with dilute acids to release hydrogen.

PHYSICAL AND CHEMICAL PROPERTIES OF LEAD:

Atomic number 82

Atomic mass 207.2 g.mol -1

Electronegativity according to Pauling 1.8

Density 11.34 g.cm-3 at 20°C

Melting point 327 °C

Boiling point 1755 °C

Vanderwaals radius  0.154 nm

Ionic radius 0.132 nm (+2) ; 0.084 nm (+4)

Isotopes 13

Electronic shell  [ Xe ] 4f14 5d10 6s2 6p2

Energy of first ionisation 715.4 kJ.mol -1

Energy of second ionisation 1450.0 kJ.mol -1

Energy of third ionisation 3080.7 kJ.mol -1

Energy of fourth ionisation 4082.3 kJ.mol -1

Energy of fifth ionisation 6608 kJ.mol -1

Discovered by The ancients

Lead is a bluish-white lustrous metal. It is very soft, highly malleable, ductile, and a relatively poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air. Lead isotopes are the end products of each of the three series of naturally occurring radioactive elements.

Vision , Mission & Values

Vision:

• Be the World's largest and most admired Zinc-Lead & Silver Company.

Mission:

• Enhance stakeholders value through exploration, innovation, operational excellence and sustainability

• Be a globally lowest cost producer

• Maintain market leadership and customer delight

Values:

• Entrepreneurship

• Growth

• Excellence

• Trust

• Sustainability

Financials:

• Witnessed exponential growth with Revenues of Rs. 11,405 crores and a record net profit of Rs. 5526 crores in 2011-12.

• Strong Balance sheet with Cash/Bank and liquid investment of Rs. 17,948 crores

Key Enablers for HZL to become “World Class”

Schemes Objectives

ENABLERS

SIX SIGMA AND QC

BENCHMARKING AGAINST

GLOBAL PEERS

TECHNOLOGICAL

UPGRADATION

L&D INITIATIVES

TEAM SYNERGY

5 S

B.S Process Enhance technical & professional competence in employees with BITS-Pilani being our Educational Partner.

Improvement Projects Encouraging and Rewarding employees to explore newer ways of delivering superior business value.

ACT-UP ( Accelerated Competency Tracking and Upgradation Program )

Identifying high performers and creating a talent pool called as “Stars of the business”

Preparing Individual Development Plan of Star Performers to enable them to take future Leadership roles

I/WE Appreciate Valuing and Appreciating employees for ideating and implementing newer ways of doing business.

Learning and Development L&D programs are designed on the basis of training need analysis to sharpen their functional expertise and improve behavioural traits.

Chanderiya Lead Zinc Smelter – Hindustan Zinc:

HZL has two types of zinc smelters, hydrometallurgical and pyrometallurgical. Both

processes are carried out at the Chanderiya Smelting Complex, Chittorgarh. Apart from the

smelters it also has a captive power plant which supports the metallurgical processes.The

hydrometallurgical smelting process is a roast, leach and electro winning process (RLE),

whereas the pyrometallurgical smelter uses Imperial Smelting Process (ISP).

Features of CLZS

SAFETY DEPARTMENT :

The Safety is one of the fundamental needs of all living beings. Accident is an unwanted event and held due to carelessness. So these should be minimized or prevented. A Worker can preserve himself by following the safety rules and precautions to get the best out of and “Individual” his physical safety essential. These are to main reasons which induce the accidents.

UNWANTED ACTS UNWANTED CONDITIONS

In the accidents incurred by the unwanted acts, the worker is directly responsible. These type of accidents are held by improper acts, carelessness, short cuts for completing work early and

overconfidence of the worker. These unwanted acts can be minimized by keeping awareness, patience in doing work. One should not touch any machine or equipment or should not do any work with out having compelete knowledge and procedure about it.

The main reason which motivate the accidents in the from of unwanted acts are as follows:

Use of machine or equipment improperly. Filling of loading the material improperly. Keeping high speed of machine. Maintaining Oiling of greasing the M/C in running condition. Poor house keeping and loose uniform Standing in unsafe condition. During working attract the attention of other worker. Use of unsafe tool and safety equipment. Have incomplete knowledge of work. Lifting or keeping the material unsafe. Disobey the instructions and rules.

There are some unsafe conditions which motivate the accidents as follows:

1. Work on gradeless machine.2. There is oil or grease on the floor of work station.3. Bad housekeeping.4. Unsafe dresses.5. Unsafe tool and design.6. Breading or absence of railing on platform.

Thus we can prevent accidents by considering the main causes unwanted acts and unsafe conditions.

If the person is assured that the tool and equipment he handles are well designed and well build have necessary guards against misuse, he can apply himself confidently to work with out being insecure and hesitant.

There are many rules for safety but main golden rules are as follows:

Comply with all safety rules and refutations. Correct of report Unsafe Conditions immediately to Supervisor. Use right tool for the right job and use it safely. Keep the work place clean and tidy. Don’t horseplay. Report accident. Report near-miss accident.

Thus safety is the basic foundation for building tall structure and defines productivity.

SAFETY EQUIPMENTS (PPE’S):

1. Safety Belt

2. Safety Shoes

3. Ear muff

4. Face shield

5. Safety helmet

6. Acid proof glasses

7. PVC Uniform for acid

8. Leather Aprin

SINTER PLANT

HZL’s CLZS zinc and lead production begins with zinc and lead concentrates wherein zinc

and lead are present as sulphides is imported from its own captive mines in India.

Concentrates is received in trucks and stored in a Raw Material House. From the Raw

Material House, it is transported to Bins in Sinter Plant by a well controlled belt conveyor

system, where along with

certain other necessary ingredients like fluxes, secondary materials and water it is mixed in a

prefixed proportion and fed to sintering machine. Sintering serves the dual purpose of

converting the sulphides into oxides and agglomerates the product into porous, high strength

lumps called sinter.

In the sintering process the sulphides of lead and zinc react with oxygen of air to form SO2 gas:

2 ZnS + 3 O2 2ZnO + 2 SO2

2 PbS + 3 O2 2 PbO + 2 SO2

The sinter plant has following main sections:

1. RMH (Raw Material Handling):

The raw material from mines is first dumped in a yard then it comes in RMH Plant through Belt Conveyor. The unloading system of belt conveyors takes the material to the respective bay through a tripper conveyor. *The tripper conveyor is like a belt, which is mounted on the head pulley and is driven by a gear coupling (spiral helical gear, the gear box is SCN 180 where S→Spur gear, C→Triple state, 180→code for size and other specifications). With the

tripper conveyor Take-up Pulley Arrangement (automatically adjustable system) is there, which prevents breaking of belt due to stretching while working. This arrangement is perpendicular to the tripper conveyor and head pulley arrangement. *

*From the belt conveyor raw material is transferred to the respective bay via Shuttle Conveyor. Water spraying is done with the help of Fly-Over, so that the powder form of material doesn’t scatter here and there. *

From the bay the material is fed into the hoppers using Pay Loaders. Hopper transfers the material on the belt conveyor, which carries the material to the Sinter building. *Impact idlers are used in driving this belt conveyor to absorb sudden shocks. Some magnetic separators are put in between the way to separate the magnetic impurities present in the raw materials.

The basic raw material used in the industry is as follows:

1. Zn Concentrate 2. Pb concentrate3. Lime Stone 4. Ferous Oxide 5. Calcium Oxide6. Silicon Oxide7. Sulphur

2. Charge Proportioning and Conditioning System:

The raw materials can be made to pass through a disintegrator and then through hammer mill to break the oversized particles. Now the material comes on the shuttle conveyor via a belt conveyor. Raw material is transferred to the respective bin via Shuttle Conveyor.

Here we have kept 13 storage bins.

6 for Zinc concentrate (cap.→50 cu.m.)

4 for Lead concentrate (cap.→50 cu.m.)

1 for bulk concentrate (cap.→50 cu.m.)

1 for iron flux (cap.→50 cu.m.)

2 for limestone (cap.→50 cu.m.)

1 for spare dross (cap.→25 cu.m.)

2 for return fines (cap.→25 cu.m.)

All bins are equipped with Vibrators and Shock Cannons to prevent blockage, provide uniform charging and separate out the undersized particles.

The feed basically contains:

1. Return fines2. Ventilation dust3. Rich gas dust4. Bag house dust5. Blue powder6. Leach residue from Copper dross leaching7. Leach residue from Cadmium plant8. Sludge from lead refinery

The raw material from the bins comes on a belt conveyor that moves on the rollers. This system is called Weigh Feeder because a rod is attached among the rollers to sense the material load in tones per hour. The speed of all weigh feeder bins is 6 times lesser than the speed of the feeder of return fines bin due to the 6 times more requirement of return fines in sinter machine. Generally the ratio between the crude charge and return fines is in the range of 1:3 to 1:5. In order to have a sulphur of 6% in the feed to sinter machine.

From weigh conveyors the charge comes on the collecting belt, common to all bins. From this belt the charge is fed to mixing drums. The mixing drum is a cylinder in which the charge is mixed with the moisture, 2 to 4% water is added for that.

Magnetic Ore Separator is applicable for wet magnetic separation of materials such as magnetite, pyrrhotite, roasted ore and ilmenite whose size is less than 3 mm and also used for iron removal operation of materials such as coal, nonmetalliferous ore and construction material and so on.The sketch of the mixing drum and its drive is somewhat like this-

Small drum

Small drum

Mixing drum

Motor

dischargeinput

Bearings:

In its mechanism the motor drives the smaller drums, which drive the mixing drum. The spherical roller bearings are provided so that no rubbing occurs. The charging and discharging is through a V-belt arrangement. In the mixing drum some intermediate cones are provided so that slipping of charge does not occur. When the charge gets stuck in between the cones then the charge find time to mix with the moisture. From mixing drum the charge goes to the conditioning drum, where further water is added. The difference between the mixing and the conditioning drum is that the no. of cones in the latter one is more. The conditioning drum maintains the amount of moisture (approx. 6%) in the charge in the sinter machine feed. In this drum lumps of charge are formed and thus size of fines is increased. The mechanism of this same as that of the mixing drum.

3. Sinter machine:

The updraft sinter machine has an area of 120 m2 and 109 pallets each measuring 3m*1m in size. There are 444 grate bars in a pallet.

To drive the sinter machine, is used a motor and a gear box system. The drive gear is flexible and it is hanged at one side of machine. It is made flexible and movable because the machine is very long, so there are jerks in some conditions. So to withstand it drive gear box is made flexible and thus the drive does not get damaged.

The specifications of drive gearbox are-

Supplier – M/S-CITROEN MESSIAN DURAND FRANCE

Type – 71 HAA-165-500F-H3C20

Input Ratio –128/18*76/3*40.078 = 7219.90

Input Speed – n1 – 1500rpm

Output Sped – n2 – 0.207-27rpm

Motor (kW) – 75

GENERAL ARRANGEMENT OF DRIVE.

Above the sinter machine the main and ignition layer bins are located. Through ignition bin charge is passed on the pallets to form the ignition layer, the thickness of which is generally adjusted to give 30mm height. The ignition layer is fired by 2 burners operating on LSHS (low sulphur heavy stack) to get about 1000C hood temperature.

The ignition gases are drawn by the ignition waste gas fan through the wind box and conveyed to recirculating gas fan. Dust and spillage are removed in a solid separator. The ignition wind box, is equipped with two screw conveyors which are to seal and discharge the sinter machine dust collecting through.

On the 1000C burnt ignition layer, is formed the main layer 360mm in all (30mm ignition layer+330mm fresh charge). The 330mm layer comes from main layer hopper which is located above the sinter machine. The burnt 30mm layer of charge with air now heats the 330mm layer of fresh charge.

Air+ O2

To supply O2, there are 3 fresh air fans and one recirculating fan supplying fresh air and recirculates to 17 wind boxes of the sinter machine. The gases above the both updraft windboxes are low in SO2, extremely humid and at low temperature. These gases are mixed with the hot gases from the discharge and of the sinter machine and recirculated to the last 3 windboxes at the discharge end of the sinter machine. There are 5 Cyclones for dust removal og ventilation air and recirculating gases in order to avoid any dust build up in the ducts and also to avoid wear of the fans.

The SO2 gas is sucked from the top and the duct is situated in the mid of the sinter machine.

The reaction is as follows-

ZnS + O2 → ZnO + SO2 ↑

The maximum of SO2 is sucked at mid and the remaining from the back of sinter machine with hot gases. The SO2 from mid is sent to Wet Gas Cleaning Plant (WGC) through a HGP with the help of booster blower.

The specifications of the plant are as follows:

Effective updraft are a of the sinter m/c 120 m2,

Width of the pallet 3.0 m

Capacity (Dry basis) Sinter material 4600tons per day

Specific Sulphur burning rate 1.6 tons per square meter per day

Sinter Production 1080 tons per day

Sulphur content of mixture <1%

SO2 content of the gases >5%

Moisture Content <7%

Bulk density of the crude charge 2.5 tons per cubic meter (Avg.)

The ignition chamber contains the horizontally arranged oil burners. Oxidation reaction produce such heat that local melting at contact surface takes place between single grains as a result of that they agglomerate into lumps. The temperature at the outlet of the sinter machine is around 800◦ C.

4. Sinter and Return Fines Handling (Crusher Plant):

Because the sinter from sinter machine is in the form of very big size lumps, which cannot be directly fed to furnace, and it needs to be broken in the size of approximately 65 to 130mm. This sizing is done in the Crusher Plant. Also, as the major part of the input to sinter plant is the return fines and for that the fines are prepared in the Crusher Plant.

Now the agglomerated material is directly fed to the claw crusher or Sinter Breaker that is placed just after the sinter machine. This crusher helps in reducing the size of sinter upto 300mm. And the temperature at this stage is approximately 500C.

Now the sinter is sent to the Spike Roll Crusher that gives the size of sinter as 130mm. Before this crusher a Vibro-Feeder is provided to give uniform charging to crusher.

Finally the material goes in the Rose Roll Classifier. The sinter of size less than 65mm and greater than 65mm is classified in this classifier. The sinter of size 65 to 130mm comes to Production Bin, which is the input for ISF Plant.

The –65mm sinter (i.e. the size is less than 65mm) passes through another circuit so that proper size of fines can be fed to the sinter input in the form of return fines. The size should be approximately 6mm for proper permeability is achieved.

The size of returns is reduced upto 25mm in the Corrugated Roll Crusher. Further the size is reduced in the Smooth Roll Crusher to 6 to 13mm, which is the required size of return fines. At this stage the temperature is approximately 300C that is further reduced to 90C in the Cooling Tower or Cooling Drum. Thus formed fines are the feed for the sinter plant.

The material, which is agglomerated in the sinter machine, is mainly rich in ZnO and PbO, which are now; send to the ISF plant to feed it to the furnace. The reaction-taking place in the plant is as follows:

2 PbS+O2 → 2PbO

2 ZnS+O2 → 2ZnO

These are sent to ISF to reduce it to Zn and Pb.

Gas Cleaning Plant

Basic purpose of the plant is to clearfy the gas Sulphur Dioxide to use it further in the Acid plant to manufacture the Sulphuric acid. The gas coming out of the sinter plant is mainly Sulphur Dioxide. This gas is allowed to pass through the ESP (Electrostatic Precipitator). High electric field is applied to charge the solid powdered substance coming with the gas. Due to that all the powdered impurities get settle down at the bottom of the precipitator. Continuous cleaning of the ESP is required to stop blockage.

Gas coming out of the Hot gas Precipitator is has a sufficiently high temperature (300 C) is now passed through the washing tower. While passing through the washing tower the gas get cooled down as well as it settles down all the solid impurities present in the gas having a sufficiently large size. Still the temperature of the gas is about 60 to 65 C which need to be get dow.

This task of bringing the temperature of the gases to the normal atmospheric temperature is done by coolers. There are six coolers installed in the plant who used to cool the gases with the continuous flow of the water.

Now the gas is allowed to pass through the fluorine separator to wash out any traces of fluorine coming with the gases. A wet gas precipitator is used in the plant to settle down any last traces of impurities in the gases. Here lead electrodes are used to charge the impurities in

the gases. The gases coming out of the plant are now at 330C and is ready to fed it to Acid plant.

IMPORTANT DATA AND PARAMETERS IN GAS CLEANING PLANT:

1. Fresh inputs to sinter machine

Zinc concentrates 18.2 T/H

Lead concentrates 7.2 T/H

Bulk concentrates 6.5 T/H

Limestone+ Lime 4.1 T/H

Iron Flux 0.2 T/H

2. Output from Sinter Machine

SO2 gas 6% 1500 m3/min

Cadmium dust from HGP 2.81 T/H

Sinter to ISF 45.61 T/H

OTHER RELEVANT DATA AND PARAMETERS:

1. Return fines from ISF 11.3 T/H

2. Moisture in feed to sinter machine 5-6%

3. Sulphide sulphur in feed to 5-6%

Sinter Machine

4. L.S.H.S. consumption per hour for 200 kg/hr

two burners

5. Ignition hood temperature 1000 deg. Centigrade

6. Ignition layer thickness 30-50 mm

7. Main layer thickness 360-400mm

8. Sinter machine speed 0.19-2.00 m/min

9. Sinter machine hearth area 120 m2

10. Crude charge return fines ratio 1:3 to 1:5

11. Concentrate size 100% less than 1mm

12. Maximum moisture in concentrate 7%

13. Flux size 100% < 5mm, 80% <2mm

14. Sinter sent to ISF, size +65mm-130mm

15. Sinter sent to ISF, quantity 45T/H

16. Sinter return from ISF 11 T/H

17. Zinc concentrate required per 0.6-0.7 Ton of sinter consumed in ISF

18. Lead concentrate required per 0.25-0.3 Ton of sinter consumed in ISF

19. Limestone required per 0.1 Ton of sinter consumed in ISF

20. Iron Flux required per 0.3 Ton of sinter consumed in ISF

21. Rattler Index of product sinter 60-80

22. Maximum size of return fines < 6 mm

23. L.S.H.S. required per 5.5-6 kilo Ton of sinter consumed in ISF

24. LDO required per 3-3.5 kilo ton of sinter consumed in ISF

SULPHURIC ACID PLANT

The acid plant used for manufacturing the Sulphuric acid is a traditional plant based on contact process for manufacturing the sulphuric acid. In the plant we have used following instruments in some fixed numbers as:

Absorption Towers (3):

1. In the gas coming from the gas cleaning plant contains a significant amount of water which is to be removed before it is allowed to enter to the catalyst chamber because water may destroy the catalyst. For that we must dehydrate it using a dehydrating agent. And the dehydrating agent frequently available in the plant is the Sulphuric acid itself. We pass the concentrated acid through the tower to absorb the water vapours in the gas. After passing through the tower the acid become dilute which is mixed with the concentrated acid coming from the other two absorption towers to maintain the concentration.

2. The second absorption column is used to convert the SO3 into Sulphuric acid. A spray of the some dilute sulphuric acid made from the top of the column and we are getting the concentrated acid from the bottom of the plant.

3. The third absorption column is used to convert the remaining SO3 into the Sulphuric acidizing the same method. The acid coming out of the last tower is approximately 98% pure. This acid is mixed with the acid coming from the other two towers to maintain the concentration. The amount of acid of each concentration getting mixed with one another is controlled from the control room

Reactors (1):

The reactor used in the sulphuric acid plant is containing a known weight of the catalyst Vanadium Penta Oxide. The Sulphur Dioxide entering into the reactor gets converted into the Sulphur Trioxide. The temperature at which the reaction is fastest is 450-620°C. So temperature from the control room is maintained between these limits. As the reaction is exothermic the temperature is maintained automatically inside the reaction vessel around the desired value. This is accomplished by taking out some amount of gas out of the column after each catalyst bed. When the gas is brought out first two times it is just cooled using the heat exchangers. But when gas is brought out after next two catalyst beds it is first through the heat exchangers and then through the absorption columns.

Heat Exchangers (6):

In plant we have total 6 heat exchangers which are being used to cool the gases coming from the reactor (On tube side). These heat exchangers are arranged in such a way that proper usage of the heat generated in the plant can be done.

Absorption Tower 1 Reactor

Absorption Tower 3

Absorption Tower 2

Cooler Heat Exchanger

To Storing Tank

Sim

plified

Diag

ram O

f Sulp

hu

ric Acid

Plan

t In P

lant

SpecificationsParameters ContentTotal Acidity (as H2SO4) 98.00% minResidue on ignition 0.050% maxIron Content (as Fe) 0.005% maxLead Content (as Pb) 0.002% maxArsenic content (as As) 0.003 % maxBulk density 1.840

End Uses

Sulphuric Acid is the bulk commodity chemical used by almost all the industries. It is the basic building molecule for chemical industry; used for different applications. The major consuming end use segments are:

1) Fertilizer (Phosphatic Fertilizers: DAP & SSP)

2) Detergent

3) Dyes & Dyes Intermediates

4) Organic & Inorganic Chemicals

5) Textiles

6) Petrochemicals

7) Refineries

8) Pharmaceuticals

9) Explosives

10) Pulp & Paper

11) Rayon

12) Alum Manufacturing

13) Sugar Refining

14) Metal Pickling

IMPERIAL SMELTING FURNACE PLANT

Introduction

The imperial smelting blast furnace is designed to simultaneously produce molten zinc and lead by smelting prepared raw materials with preheated coke and preheated blast air.

The prepared, agglomerated raw material (sinter) is fed to the top of a vertical shaft furnace together with the heated coke. Air is blown into the bottom of the shaft and the chemical reaction between this air and the coke produces carbon monoxide and generate heat to smelt the metallic oxide in the charge into the elemental metal. Molten lead falls into the bottom of the furnace from where it is tapped together with slag of a molten gangue material. At the temperature of operation, metallic zinc is formed as a vapor and rises up the furnace shaft with the furnace gases. These zinc containing gases pass through a furnace off take into the condenser containing molten lead. Here zinc is condensed to a liquid by shock cooling, the gases with a spray of finely divided droplets of lead generated by rotors immersed in the lead. After absorbing condensed zinc, this lead is pumped out of the condenser into a adjacent

cooling launder where it is cooled by tube banks immersed in the launder from above. At the end of the launder the zincy lead is treated with flux and flows into a separation bath where, at the cool temperature of 440 deg cent., zinc separates as a molten layer on the top of lead. Zinc continuously overflows via a V- notch into a adjacent liquation bath whilst the main lead stream passes from the separation bath under the underflow weir and then into a return launder leading back into the condenser.

The liquation bath is small bath in which any final separation of lead and iron from the zinc can occur before the zinc overflows to the final holding bath. Here it is allowed to accumulate before being tapped for casting or further treatment in zinc refinery.

The waste gases leaves the condenser after zinc is condensed from them are passed into a gas cleaning system where they are cooled and cleaned of particulate matter. These gases contain carbon monoxide and have a low calorific value. After cleaning calorific value is utilized in preheating the furnace blast air and in preheating the coke; any remaining excess gases is used in the site power plant boilers.

FURNACE

The ISF consists of three sections-the upper section ( or furnace shaft) which contains furnace gases off take, and intermediate section with a shower cooled casing and the lowest section- the furnace hearth. All three section are joined together to give a gas tight construction in which the charged is smelted.

The sinter and coke are fed into the shaft though two sets of charging gears situated in the furnace roof and blast air enters through tuyeres set in the lower portion of shower cooled casing. Lead and slag are tapped from the furnace hearth and furnace gas and zinc vapor leaves the shaft through furnace off take which is set in one side above the top level of charge.

CONDENSER

Zinc condenser is essentially a refractory lined steel tank containing molten lead with a gas above through which furnace off gases are passed. Furnace gas enters the gas space from the furnace off take and flow through the lead spray in three condensation stages before leaving the condenser through the vertical off take stack at the rear. The condenser has a shallow inverted arch refractory floor and a demountable shallow arch roof formed from cast iron and mild steel tiles. It is divided into three sections by vertical steel baffles to form three distinct condensation stages. In each stage steel baffles are there to form three distinct condensation stages. In each stage vertical rotor units are suspended from above with the rotors immersed

below the normal lead level. The rotors are designed to throw the spray of lead droplets into gas space in order to condense zinc vapor contained in the furnace off takes.

The condenser gas off take is a regular refractory lined stack fitted with internal liner plates. The gas pass up the stack before leaving through a doubly inclined cross over duct leaving to the gas washing tower. The off take stack is provided with doors in prder to provide facility for cleaning.

Sinter + Hot Coke

Condenser

Fore HearthFurnace

Zinc Vapour

Slag to Yard

Lead Bullion to LRP

Cowper Stove

Gas Cleaning Section

Coke Preheater

Coke

BP Thickener in ETP

Separation Bath

Liquation Bath

Holding Furnace

Furnace Zinc to ZRP

Lead

Imperial smelting furnace

LCV Gas

Pump Sump

Cooling Launder

ISF PROCESS FLOW CHART

LEAD COOLING AND METAL SEPERATION SYSTEM

Hot lead delivered from the condenser lead pumps is cooled so that dissolved zinc separates as a second liquid phase and floats of the lead from where it can be removed by physical separation. Cooled lead reduced in zinc contents is returned to the condenser so that it can condense more zinc from the furnace gases.

The metal separation system consists of two connected baths between the cooling launder and the return launder to the condenser, and two baths which form a side stream route for the zinc output metal.

As lead enters the flux bath about 20 kg per hour of ammonium chloride pellets are added from the hooper and feeder system. This flux is added to minimize turbulence and the oxidation of zinc. The lead enters into a section from which it flows out over a submerged baffle, this arrangement being adopted to ensure that the ammonium chloride is thoroughly mixed into the lead and that dross is brought to the surface. The flux bath is roofed and the point of flux addition is hooded for ventilation purpose. Lead flows out of the bath via an underflow weir to prevent dross carry over to the separation bath.

From the liquation bath zinc overflows to the zinc holding bath which is a surge bath allowing zinc metal output to accumulate before being tapped into ladles or moulds from transfer to zinc refinery. This bath also provides a facility for reheating molten zinc to between 480 to 520 deg cent.which is temperature required for further handling.

At the separation bath, zinc overflows the V-notch and falls into the liquation bath. The purpose of this small bath is to provide facility for removal of impurity from zinc to maintain the grade of zinc passing to the zinc refinery. Iron is removed in the hard metal which gradually forms a layer under the zinc as is cools. Lead carry over and settle in this bath and may be tapped and removed from time to time for return to cooling launder as lead ingot.

All the baths of the metal separation system are of a refractory lined metal casing construction, have removable refractory lined roof tiles and are fitted with a burner and cleaning rods. In the sides of the bath, refractory tapping blocks allow metal to be drained out when required. All baths are provided with ventilation ducts which passes through the roof tiles and ventilation hoods are provided over the dross discharge areas.

GAS WASHING PLANT AND LCV DISTRIBUTION SYSTEM

Introduction

The purpose of these systems is to cool the condenser off gas, to remove particulate matter and to produce and deliver a clean, low calorific value gas suitable for burning in coke preheaters, Cowper stoves and power generation plant. The particulate matter, containing zinc and lead oxides and other fine particles carries over from the furnace(blue powder) is washed out of the gas and collects as a slurry for subsequent thickening and return to sinter plant.

Gas cleaning is accompanished by a preliminary cleaning and conditioning operation in a unpacked co current spray tower, followed by scrubbing in a special high speed irrigated fan known as disintegrator. Water droplets are then removed from the gas in a cyclonic separation and the gas pressure is booted for distribution to the gas consumers.

The dirty liquor drains to a dredge tank from which it is collected for pumping to a thickener. This tank is 15m long and run under the three units, gas washing tower, disintegrator and moisture separator. It serves both as water seal and as a slurry collection tank for each unit.

LCV GAS DISTRIBUTION

The function of this system is to distribute the cleaned LCV gas from the outlet of the moisture separator to the three major consumers, or to release from the system via the flare stack at periods of low consumption.

The gas booster fan is used to control the pressure in zinc condenser and the gas washing system and to deliver gas at the required pressure into the LCV gas header main for supply to Cowper stoves, the coke preheaters and the boilers of the power generation plant.

DREDGE TANK AND BLUE POWDER DISPOSAL

The dredge tank forms a reception tank for the drain from the component of the gas washing system, and also acts as a water seal for all the down comers. Scrubbing water drain into the tank carrying with all solids scrubs from the condenser gas. The heavier solid particles settles to the bottom of the tank while the major part of the liquor carries away the smaller suspended particles and flows over a weir on the side of the tank into a line leading to a blue powder pump tank.

At the blue powder slurry pump tank two slurry pumps, one operating and one stand by, pumps the blue powder suspension onto a high level open launder leading to blue powder thickener. Pumps also discharge liquor from the blue powder sump and the blue powder slurry tank to the launder. Lump material from the lump bunker is moved to the sinter plant.

AUSMELT PLANT

PROCESS SELECTION

Considering various processes options available such as sinter blast furnace, imperial smelting furnace, and direct smelting process etc, HZL proposed for Top Submerged Lance (TSL) technology based on direct smelting process at CLZS. TSL technology enjoys distinct advantages over other technologies. The superiority of TSL technology lies in its compact cylindrical vessel designs which leads to better pollution control, high energy utilization.

FEEDING SYSTEM

The function of the feeding system is to feed the charge or concentrates from the RMH section to the furnace, In this various belts. Bins and other equipments are used for transferring the charge. Bin 01 is situated at the ground floor. All the concentrates are first fed into this bin coming from the RMH section. From this bin the concentrates are passed on to conveyer belt CV 01 through a magnetic separator at which all the iron particles are removed. CV 01 is a high angle conveyer belt. From CV 01, the concentrate goes to CV 02 and then to CV 03. CV 03 is a kind of belt that can move in both the directions hence called reversible belt and below it there is a shuttle having holes at the bottom through which the concentrates are fed into the bins. For bin 01 to bin 04 the conveyer move in one direction and for the rest of the bins, it moves in the opposite direction. There are 10 bins.

The concentrates present in the bins are:

Bin Material Capacity

Bin 03 Lead Concentrate 70 m3

Bin 04 Silica Flux 25m3

Bin 05 Limestone 25m3

Bin 06 Lead Concentrate 32 m3

Bin 07 Arsenic Dross 25m3

Bin 08 Lead Sludge 25m3

Bin 09 Reductant Coal Revert 25m3

Bin 10 Recycle Dust 25m3

Below these bins weigh feeders are present through which a required amount of concentrate is passed. From bins, the concentrates is passed into the Pug Mill via CV 04 which is also reversible for throwing the extra charge down again. In pug mill moisture is added. From pug mill, the concentrate is passed into the furnace via CV 05, CV 06 and CV 07 (reversible).

PROCESS DESCRIPTION

Selected process for proposed lead smelter is based on Top Submerged Lance Technology. In this process, a concentrate is smelted directly in a cylindrical furnace. The furnace is designed especially for this process. At the roof of the furnace there are 4 ports, one for feeding, second for lance, third is for sample dipper and the last one is for stand by burner which is used to heat the refractory bricks and also used when lance is not working. Lance has 4 concentric tubes through which air, enriched oxygen and oil is passed. This oil is atomized and its combustion tales place. The bath height in the furnace should not exceed 1.4 m. The lance can move up and down which is controlled from the control room.

Lead concentrate along with recycle dust of the furnace and flux are fed into the furnace after agglomerating the feed in the pug mill. Air enriched with oxygen is introduced into the furnace along with fuel via lance. Lance rod is used to burn and agitate the lead concentrate in the slag already present in the furnace.

Total process is completed in three stages:

1. Smelting2. Slag Reduction3. Slag Cleaning

All these three stages happen in the same furnace. In the smelting stage concentrate, recycle dust, fluxes are fed into furnace and oxygen enriched air and fuel is fed through a vertical lance which is kept submerged into the slag of previous batch. Sulphide concentrate is oxidized to lead oxide and produced lead is tapped intermittently from the furnace.

Reaction that takes place at the smelting stage:

PbS + O2 - PbO + SO2 (12 %)

PbO + PbS + O2 = Pb = SO2

Slag produced in smelting stage will have 40 % lead content which will be further reduced in the next stage- slag reduction stage. In this stage all the other feed is stopped and coal is charged through the feed port. Oxygen enrichment through the lance is also stopped. Coal acts as reducing agent and it reduces the lead oxide to lead bullion, which is tapped from the furnace.

Reaction taking place at the reduction stage

PbO = C = Pb = CO2

Resulting slag after this stage inside the furnace contains 5 % lead and zinc which is recovered in the third stage- slag cleaning stage. In this stage no bullion is produced, lead and zinc in the slag is recovered in the form of oxide after fuming the slag. This zinc and lead oxide collected from the Waste Heat Recovery Boiler and hot ESP, is recycled int eh existing sinter plant to recover lead and zinc from it. Dust collected in other stages is recycled in the furnace itself.

Off gases at a temperature 1150 – 1400 deg cent from the furnace is cooled to 350 deg cent by waste heat recovery boiler. Steam generated in the boiler is sent to the leaching section of the hydrometallurgical zinc smelter. The cooled off gases are cleaned in the hot ESP. Dust content in the off gas after hot ESP will be below 100 mg / Nm3

. Off gas will be further cooled and cleaned in the Quench Tower, where water is sprayed from the top and gas are passed from the bottom in the counter current direction of water. Here the temperature of the gases drops to 60 – 70 deg cent. The gas is then transferred to Packed Gas Cooling Tower (PGCT) from where the gas is passed to the Wet Est. Here the remaining dust is cleaned by spraying water and then the gas is fed to the sulphur dioxide gas recovery section or Absorption Tower where amine is added called lean amine from the lean amine tank which absorbs SO2 and becomes rich amine which is then transferred to the regenerator. Since this amine is very costly so we circylate the same amine by extraction the absorbed SO2 in the regenerator by using steam. This SO2 is cooled and transferred to the Acid Plant to produce Sulphuric Acid.

AUTOGARAGE

In the auto garage there are 3 HP Loaders (2071), 3 JCB and 13 Fork Lifts.

A HP Loader has a 450HP engine and works on automotive power transmission. It can lift weight up to 10.5 tonnes. The bucket has a volume of 3 cubic metres. The engine produces power of 400HP and 50HP due to the turbo charger. When viewed from fan side the turbocharger runs in right hand rotation, i.e., clockwise rotation. The small bucket has a volume of 4.5 cubic metres. But due to less density and due to cork it can only lift weight up to 2.5 tonnes only. It has 4 gears 2 in forward direction and 2 in reverse direction. The engine used in HP loader is of Commins.

The Fork Lift works on both fluid transmission as well as automotive transmission. The engine produces power of 50HP. The engine used is of Simpsons in Fork Lift.

To facilitate the loading, unloading of raw material being received from the mines and to move the ingots of refined lead, zinc and silver and for the movement of heavy machine elements in the plant there are 13 fork lift trucks and 3 pay loaders in the plant.

The maintenance of these vehicles and all other company vehicles come under the auto garage section of the CSC.

The specifications of the machines are-

Pay loaders-

Manufactured by- Hindustan motors that’s why they are called HM loaders

Model no. 2071

Engine is manufactured by Cummins India Pvt. Ltd. Pune

The 6 cylinder CI engine generates 430 HP power and has capacity of 10 tones.

JCBs are of 3 manufacturers-

Escorts, JCB and Ashok Leyland and they produce 127 HP of power.

Lifters-

Diesel Fork Lifts model no.-DU30-ATP-HMV super

Height-4100 mm

Load- 3000 kg

Godrej Fork Lifts- Model G*360 capacity of 3000 kgs.

Road Sweeper-

Manufactured by Tennant in USA.

Mechanical Workshop

Although all the plants in the Chanderiya Smelting Complex have their own mechanical workshops to make jobs as per the need of the plant machinery.

But if the job is too large for the plant workshop then it is sent to the central mechanical workshop for completion.

In central mechanical workshop there are mainly three sections as-

1. Turning Section2. Fitting section3. Welding Section

In turning section there are lathe machines, shaper machines, and milling machines.

Three main elements of working on a lathe machine are-

Rotating Speed

It expresses with the number of rotations (rpm) of the chuck of a lathe. When the rotating speed is high, processing speed becomes quick, and a processing surface is finely finished. However, since a little operation mistakes may lead to the serious accident, it is better to set low rotating speed at the first stage.

Cutting DepthThe cutting depth of the tool affects to the processing speed and the roughness of surface.

When the cutting depth is big, the processing speed becomes quick, but the surface temperature becomes high, and it has rough surface. Moreover, a life of byte also becomes short. If you do not know a suitable cutting depth, it is better to set to small value.

Sending Speed (Feed)The sending speed of the tool also affects to the processing speed and the roughness of surface. When the sending speed is high, the processing speed becomes quick. When the sending speed is low, the surface is finished beautiful. There are 'manual sending' which turns and operates a handle, and 'automatic sending' which advances a byte automatically. A beginner must use the manual sending. Because serious accidents may be caused, such as touching the rotating chuck around the byte in automatic sending.

Operations performed in turning section-

Turning- It is the process of removing excess of material from any work piece to give it the required dimension and surface finish.

Facing- It is the operation in which material is removed from the work piece along its length to make it shorter in length to meet the requirement of the machine.

Taper Turning- This process is similar to that of turning but in his process the material is removed in such a way that finally the work piece is in tapered shape as per the drawing.

Threading- Threads are important element of permanent fastening and they also play their role in machine element in various ways.

Chamfering- it is the process of making the ends of a job in tapered shape so that they do not have sharp corners that can hurt the person working with that work piece.

Knurling- It is the process of embossing diamond shape on the work piece so that to make gripping portion on the shaft to make it easy for the workmen to hold it.

Machines in CMW/s-

Lathe Machines- 4

Shaper machines- 2

Milling machines- 1

Power Hacksaw-1

The lathe machines are made by HINDUSTAN MACHINE TOOLS LTD> and are fittrd with motors manufactured by THE MYSORE KIRLOSKAR LTD.

The Shaper machine is made by sagar heavy engineering pvt. Ltd., Ludhiana

The Power hacksaw is of COBRA model.

Fitting Section-

In fitting main machines are drilling machines, pressing machine, bending machines.There are the following machines in the fitting section of the CMW/s-\

Radial drilling machine-1

This is used to drill holes in large jobs. The work piece is placed and fastebed to the drill jig of the machine and then holes are bored in the job.

This machine is manufactured by HINDUSTAN MACHINE TOOLS LTD and operates at 2 different set of speeds.

Column Drilling machine-1

Column drilling machine is used to drill hole in comparatively small work pieces. It is manufactured by HINDUSTAN MACHINE TOOLS LTD.

63T-Press-1

It is manufactured by UI Dynamic.

Bending Machine-1

Tool Grinding machine-1

Welding Section-

Welding is the process of joining two metals or non metals with application of high temperature on account of local melting of the pieces to be joined with or without application of pressure.

In the welding section of the CMW/s the worn out or broken parts are welded.

Main types of welding processes used at the welding section of CMW/s are gas welding and electric welding.

In gas welding the metal pieces are heated with help of high intensity flame generated by burning of mixture of acetylene and oxygen in proper ratio.

In electric welding the metal pieces are joined by using filler rod to which low voltage high intensity current is supplied which generates very high temperature of 1000-1500 degree Celsius and the parts are joined together.

CONCLUSION

The whole process of recovering zinc and lead from the feed driven from mines is known as Pyrometallurgy in which temperature plays a very vital role. Initially Pb and Zn concentrates are being put up into the bins from which sinter is prepared by agglomeration process done in the sintering machine at a temperature around 1000 deg. Cent. Also generation of SO2 is there which is further used in the production of sulphuric acid. Sinter is next transferred to Imperial Smelting Furnace (I.S.F.) where sinter at 400 deg. Cent is charged along with coke at 800 deg. Cent as well as addition briquettes and a hot blast of air is passed into the furnace where PbO and ZnO are reduced by coke to the corresponding metals producing CO gas. Since boiling point of Pb is very high therefore it remains in molten from and taken along with slag in a Fore hearth, Due to the difference in densities. Pb is being separated and taken as an underflow. Zn vapours and finally temperature is lowered to 440 deg. Cent in order to separate PB and Zn is recovered in a zinc holding bath whose purity is around 98%.

These Pb & Zn obtained from ISF then goes to the refineries where impurities are further removed to obtain the metals at 99.9% purity. There are also copper and silver refineries to produce pure copper and silver derived from lead refinery process.

Another technique used in the Pb extraction is derived from Australia known as Ausmelt in which Smelting and reduction is done in the single furnace known as Ausmelt furnace and does not need sinter formation. Off stake gases are cooled and cleaned in a gas cleaning plant and SO2 is absorbed and taken to the acid formation plant.