tailing management, bench report on · material by a roll crusher product to make it slurry with...

M/s Bhagavathi Ana Labs Pvt Ltd., (A Bureau Veritas Group Co)

Tailing Management, Bench formation & Stabilisation

Report on Tailing Management, Bench

formation & Stabilisation

2017

Jindal Stainless Limited

Jindal Chromite Mines, Kaliapani-755047, Jajpur (Odisha)


C O N T E N T S

Sl Contents Page No.

- LIST OF FIGURES & TABLES 3

- SUMMARY RECORD OF 13th MEETING OF THE EXPERT

APPRAISAL COMMITTEE FOR MINING PROJECTS UNDER EIA

NOTIFICATION, 2006.

4

A. REPORT ON TAILING DISPOSAL

1. MINING OPERATIONS OF JINDAL CHROMITE MINES 5

2. Details of COBP -1 6

3. DETAILS OF COBP -2 (NEWLY INSTALLED) 9

4. TAILINGS / REJECT MANAGEMENT FROM THE PROCESSING PLANT

12

5. DETAILS OF TAILING DISPOSAL 14

6. WATER MANAGEMENT FOR TAILING DISPOSAL 15

7. TAILING MANAGEMENT DURING MONSOON 18

B. BENCH FORMATION & STABILIZATION 20

C. DETAILS ON TIGER CORRIDOR 24


LIST OF FIGURES & TABLES

Sl Figures / Tables Page No.

A. LIST OF FIGURES

FIG - 1 PROCESS FLOW- SHEET OF COBP # 1 6

FIG - 2 PROCESS FLOW OF COBP # 1 7

FIG - 3 PROCESS FLOW- SHEET OF COBP # 2 10

FIG - 4 PROCESS FLOW OF COBP # 2 11

FIG - 5 GENERATION OF BENIFICIABLE MINERAL REJECT, CONCENTRATE AND TAILING

13

FIG - 6 FLOW-SHEET OF TAILING DISPOSAL 14

FIG - 7 HDPE LINED TAILING POND 16

FIG - 8 MAP SHOWING TAILING POND LOCATION 17

FIG - 9 EFFLUENT TREATMENT PLANT- ENSURING ZERO DISCHARGE

19

B. LIST OF TABLES

TABLE - 1 YEAR-WISE GENERATION OF TAILINGS 12-13

TABLE - 2 SALIENT FEATURES OF EXISTING CHROMITE MINING

METHODS

21


GOVERNMENT OF INDIA

MINISTRY OF ENVIRONMENT, FOREST & CLIMATE CHANGE

(IMPACT ASSESSMENT DIVISION)

NON-COAL MINING SECTOR

SUMMARY RECORD OF 13th MEETING OF THE RECONSTITUTED COMMITTEE OF THE EXPERT

APPRAISAL COMMITTEE FOR ENVIRONMENTAL APPRAISAL OF MINING PROJECTS

CONSTITUTED UNDER EIA NOTIFICATION, 2006.

The Thirteen meeting of the Reconstituted Expert Appraisal Committee for Environmental

Appraisal of Mining Projects (Non-Coal) of the Ministry of Environment, Forest & Climate

Change held during December 15-16, 2016.

Proposal Number:

IA/OR/MIN/52974/2016

Project:

Expansion of Jindal Chromite Mine with production capacity from 0.1 million TPA to 2.15

million TPA of Chrome Ore of M/s Jindal Stainless Limited located at Village: Kaliapani, Tehsil:

Sukinda, District: Jajpur, Odisha (ML Area:89.0 Ha.)-.

The proposal is for Expansion in production from of 1.0 LTPA to 2.15 LTPA of Chrome Ore from

89 ha Mine lease area located at Village-Kaliapani, Tehsil Sukinda, District Jajpur, Odisha

Based on the information furnished and presentation made and discussions held, the

Committee deferred the Proposal and sought the following information:

(i) A detail report on tailing disposal and proper bench formation and stabilization.


A. REPORT ON TAILING DISPOSAL : 1.0 MINING OPERATIONS OF JINDAL CHROMITE MINES Jindal Chromite Mine is a Captive Lease allocated by Government. Chrome Ore produced from the lease can only be used in Captive Chrome Based Plants. Besides Cr2O3 other components are suitable for ferro chrome / charge chrome / silico chrome plants. The Chrome ore produced from the mine is being consumed by the ferro chrome plants of the lessee at Kothavalasa of Andhra Pradesh, Hissar of Haryana and the Stainless Steel plant at Duburi, Jajpur Road. Since these plants require high grade ore having around 46% to 48% Cr2O3, the ROM ore with around 44% Cr2O3 is sent to these plants while the ROM mineral rejects (10 to 40%) is stacked separately. JSL has set up a Chrome Ore Beneficiation Plant (COBP) within the leasehold area to upgrade the Mineral Rejects out of the ROM. With the recommendation of IMMT (RRL) Bhubaneswar, the plant production was optimized at 40% yield, production of concentrate having 44 – 45% approx. of Cr2O3 and plant production capacity was maintained at 36000 tonnes/ annum. In the meantime the quality of low grade in the mine was further deteriorated and the Cr2O3

analysed 16 – 18% which could not be processed in the plant. IMMT (RRL) Bhubaneswar has further conducted a feasibility test for recovering the Chrome Values from the sub grade ore as well as the tailings and encouraging results were obtained. Immediately IMMT, Bhubaneswar was entrusted to prepare DPR for setting up an additional facility for recovering the chrome values. IMMT suggested for modification in the Beneficiation plant to add one new circuit for processing the sub-grade ore with a facility for froth flotation. The proposal was for a feed capacity of 20 TPH for both the material i.e sub-grade ore and tailings. But both the materials shall be processed separately in the same plant. The plant shall be operated in all the 3 shifts and is expected to process 128000 tonnes / annum and can produce 25600 tonnes of chrome ore concentrate around 46 – 47% Cr2O3 with Cr:Fe at 1:8. Keeping the above up-gradation into account for both sub-grade and tailing M/s JSL has installed another COBP with a capacity of 24000 tonnes / annum adjacent to existing one for which MoEF & CC has accorded Environmental Clearance on 24.02.2016. This plant is yet to be started.


2.0 Details of COBP -1

The details flow sheet of COB Plant for sub-grade and tailing is as follows:

FIG : 1 : PROCESS FLOW-SHEET OF COBP – 1


-200mm

-15mm

-6mm+ water

-0.5mm +0.5to -6mm

0.3mm

Over Flow

Middling

C M T C M T C M T C M T

Tailing

C- Concentrate M- Middling T-Tailing

Feed Hopper

Screen & Jaw Crusher

(Crushing up to -15mm)

Secondary Screen & Roll Crusher

(crushing up to -6mm)

Drum Scrubber (Slurry mixing

and scrubbing gang particle)

Grinding Rod Mill

Hydrocyclone 2 nos

clusters(Separation of

impurities)

Wet Screening

Hydrocyclone2

Clusters

Shaking

Table4&5

Shaking Table

1&2(gravity

separation)

Shaking

Table3

Shaking Table6

Screw Classifier

COBP-II

CONCENTRATE

FIG : 2 : PROCESS FLOW OF COBP – 1

CHAR


The gist of COBP -1 for sub-grade are as follows:

Feed grade : Having Cr2O3 of 28 -30%

Feed rate 16 TPH

Concentrate production : 6.5 TPH (approx.)

Concentrate grade : 44 – 45 % Cr2O3

Yield : 40%

1. The 200mm-300mm size low grade ore of 28-30% Cr2O3 content material is fed in to a

60MT Capacity hopper with 200 mm size grizzly, so that -200mm size material passes through the grizzly.

2. A variable speed reciprocating feeder is installed under hopper to feed 10-15 TPH of ore to belt conveyor 600mm width.

3. The belt conveyer feed 200mm size material to a vibrating screen having 15mm aperture which screen-15 mm size material and is fed to conveyor 1450mm width.

4. The oversize of screen is crushed in to a jaw crusher, which converts +15mm size material to-15mm.

5. The screen under flow and crusher product is sent through a belt conveyor of 450mm width, to another vibrating screen with 6 mm aperture, which gives a product of -6mm size

6. The Over sized material of vibrating screen i.e. +6mm material is reduced to-6 mm size material by a roll crusher product to make it slurry with help of a slurry pump with agitator.

7. The slurry pump gives feed to Drum Scrubber, which scrubs the ore with water. 8. A Double Deck Vibrating Screen with top aperture 2 mm and bottom aperture 0.75 mm is

provided, which takes the feed from scrubber 9. The bottom deck product, which is -0.75mm in size is fed through sump to a hydro

cyclone cluster to separate heavy materials and gangue from slime. 10. The under flow of hydro cyclone cluster No.1 is fed to one number of shaking table, which

separates the material in to concentrate, middling and tailing. 11. The overflow of hydro cyclone cluster one is fed to hydro cyclone cluster no2 which feeds

to shaking table which separates the material in to concentrate, middling and tailing. Likewise, there are 6 sets of hydro cyclone cluster and operation is vice versa.

12. The over size of double deck screen is fed to Rod mill, which grinds the material to -0.3mm size. This material is send to 1 cluster of hydro cyclone and then to table to recover the concentrate.

13. The concentrate from all the tables is collected in one sump and then sent to dewatering screw classifier and the product of classifier is our final concentrate.

14. All the middling collect in one sump are pumped to cluster of hydro cyclone recover chromite from it. The over flow is sent to COBP-2 for further process.


3.0 DETAILS OF COBP -2 (NEWLY INSTALLED) Tailings generated from COBP-1 will be further processed in COBP-2 .This will be divided into two circuit’s i.e tabling and flotation circuit. From Floatation circuit, the production will be around 1.2 TPH and from tabling the production will be around 2.8 TPH with a total production of 4 TPH.

Feed grade : Tailing having Cr2O3 of 17 – 19% (Generated from COBP-2)

Feed rate : 20 TPH

Concentrate production : 4 TPH (approx.)

Concentrate grade : Around 46 – 47 % Cr2O3

Yield : 20%

After processing of low grade ore of 20% of the material (volume) is recovered and balance 80% (Volume) (< 10% Cr2O3) will be keep in the HDPE Lined tailing pond.

The tailings of COBP-1 will be pumped to a classifier for dewatering and subsequently screening at 0.5 mm with the help of double deck vibrating screen and all the material to – 0.3 mm sized by rod mill.

All coarse material i.e –0. 5 mm size will be tabled after treating in clusters of hydro cyclones and tailing from the tables which contain very fine size chromite particles shall be pumped to thickener and the sludge from the thickener will be pumped to flotation plant.

The sludge will be treated in series of conditioning tanks. In the first tank the sludge will be diluted and solution will be treated with sodium hydroxide for bringing the pH value to 7 or 8.

Subsequently the diluted sludge will be treated with sodium silicate, CMC, Oleic acid and Pine oil in different stages and send to primary flotation cell for recovery of chromite, which floats out as overflow by froth flotation.

The chromite thus obtained as overflow shall be cleaned in three stages to get chromite of around 46-47 % Cr2O3 and at a yield of 20 %.

The chromite particles being very fine particles, hence a belt filter is used to dewater the product.

Rejects of primary flotation cell pass through one scavenger cell, where the residual chromite values can be recovered and the chromite thus obtained is recycled in the process.


All flotation cells are provided with conditioning tanks before it for reconditioning the liquid.

The residual of scavenger cell will be total waste and pumped to thickener will be recycled and re-used in the process.

The tailing produced from the COBP-2 will be treated with ferrous sulphate solution and disposed off to tailing pond at mines.

FIG : 3 : PROCESS FLOW-SHEET OF COBP – 2


The detailed flow-sheet of the process of COBP # 2 is illustrated below :

FIG : 4 : PROCESS FLOW OF COBP – 2


4.0 TAILINGS / REJECT MANAGEMENT FROM THE PROCESSING PLANT

As mentioned above, the tailings are generated from both COBP –1 and COBP -2 during process of the mineral rejects out of the ROM. The tailings generated from COBP -1 (Cr2O3 of 17 – 19%) with a yield of 60 % tailings are stored for further processing in COBP -2. The tailings generated from COBP-2 are finally disposed off to the Tailing Pond, made with HDPE lining with geo-textile liners. The year-wise generation of Tailings from both COBP -1 and COBP -2 for the revised Mining Plan period (i.e. up to 2021-22) is summarized below.

Year Wise Generation of Tailing

Year

Mines

Generation of

Mineral Reject

COBP-1 COBP-2

Source Feed (in

MT)

Concent

rate (in

MT)

Tailing

(in MT) Source

Feed (in

MT)

Concentrate

(in MT)

Tailing

(in MT)

2017-18 99,927MT

- - - Existing

Tailing

Of

COBP-1

1,20,000 24000 96000

2018-19 2,14,355MT 1,20,000 24000 96000

2019-20 49,350MT

Rom

From

Mines

40,000 16,000 24,000

Existing

Tailing

Of

COBP-1 96000 24000 96000

COBP-1

Tailing

Fresh

24000

2020-21 74,087.5MT

Rom

From

Mines

66000

24,000 96,000

90,000 36,000 54,000

COBP-1

Tailing

Fresh

54000

2021-22 41,292MT 90,000 36,000 54,000

Rom

From

Mines 66000

24,000 96,000


Year Wise Generation of Tailing

Year

Mines

Generation of

Mineral Reject

COBP-1 COBP-2

Source Feed (in

MT)

Concent

rate (in

MT)

Tailing

(in MT) Source

Feed (in

MT)

Concentrate

(in MT)

Tailing

(in MT)

COBP-1

Tailing

Fresh

54000

Total 4,79,011MT Rom

From

Mines

2,20,00

0

88,000 1.32.00

0

Rom

From

Mines

132000 1,20,000 480,000

TABLE : 1 : YEAR WISE PROPOSED GENERATION OF TAILING

FIG : 5 : GENERATION OF BENIFICIABLE MINERAL REJECT, CONCENTRATE AND TAILING


5.0 DETAILS OF TAILING DISPOSAL

The details of process flow of Tailing disposal is presented below,

FIG : 6: FLOW-SHEET OF TAILING DISPOSAL

There are two nos of Tailing ponds i.e. Tailing Pond-1 and Tailing Pond-2 with a capacity of 45000 MT(Metric Tonnes). The Tailing Pond -1 is of size (134.5m X 22.5m X 4.5 m) will hold approximately 13500Cum or 20250 tonnes and the tailing pond-2 is of size 80m X 30m X 7m having tailing holding capacity of 16500cum /24750 MT . Tailings of COBP -1 will be feed directly to the COBP- 2 .Hence the monthly generation of Final Tailing is 8000 MT. approximately. Tailing pond -1 and Tailing pond -2 can accommodate tailing generation for 5 months. To dispose the remaining tailing, another Tailing Pond i.e Tailing Pond-3 of capacity 5,00,000 cum / 7,50,000 MT is proposed. As per the approved Mining Scheme for the period 2017-18 to 2021-22 total tailing generation is 4,80,000 MT . Hence balance tailing generation i.e. 4,35,000 MT can be accommodate in the Tailing Pond-3.


The sides of the tailing pond have been provided with free board of 1m. in order to avoid surface runoff entering the tailing pond from outside. During the period 2003-04 to 2015-16 , 343000 MT i.e 228667 m3 of tailing was generated which were dried completely and preserved with Environment protection measures like toe wall, garland drain. for further process in COBP-II . in a earmarked area as per approved Scheme of Mining .Which will be processed at COBP-II with a yield of 20% in the year 2017-18 to 2019-20 . The tailings generated in the proposed COBP – 2 will be treated with adequate quantity of ferrous sulphate solution, before putting it in the tailing ponds at mines. Fines of un-recoverable size having less than 6 – 7% Cr2O3 content will be disposed off in the mines tailing pond with protection. The capacity of these ponds are designed to hold both tailing and water including rain water during monsoon with adequate free board of minimum 1m. Water from the pond will be continuously recycled as make up water in COBP –2. The Tailing pond area is provided with adequate toe guard protection and garland drains all around. The lining of tailing ponds will be of impervious in nature. A high density poly ethylene (HDPE) sheet / layer will be provided to protect the permeability on all sides and floor of the Tailing ponds. 6.0 WATER MANAGEMENT FOR TAILING DISPOSAL : The capacity of these Tailing Ponds are designed to hold both tailing and water including rain water during monsoon with adequate free board of minimum 1m. Water from the pond will be continuously recycled as make up water in COBP. The COB plant requires 5550 cum/day of water. Out of 5550 cum/day, process water is 4950 cum/day which is recycled from tailing pond and rest 50 cum/day is taken from Borewell and 550 cum/day from Mine Pit as make up water.


FIG : 7 : HDPE LINED TAILING POND


FIG : 8 : MAP SHOWING TAILING POND LOCATION


7.0 TAILING MANAGEMENT DURING MONSOON:

Tailing ponds are provided with adequate freeboard of 1mtr. to avoid any surface runoff flow in

to the pond and vice versa. Rain water collected inside the catchment of tailing pond are

recycled to COB Plant for process water and that quantity of water will less drawn from quarry

sump.

JSL has undertaken an effluent treatment plant (ETP) of capacity of 250m3 /Hour to treat the Hexavalent chromium &TSS. Hexavalent chromium is a strong oxidizing agent and can readily be reduced to trivalent chromium by means of adding reducing agent i.e. Ferrus Sulphate (FeSO4).After proper mixing with Ferrus Sulphate in flash mixer the hexavalent chromium(Cr6+) is reduced to trivalent chromium (Cr3+) while Ferrus ion will be oxidized to Ferric ion Fe3+. In the next stage by adding alkaline reagent i.e. Sodium Hydroxide (NaOH)/Lime Ca(OH)2 the ferric ion and Chromium ion will be precipitated jointly at pH 8.0-8.5 as ferric Hydroxide [Fe(OH)3] and Chromium Hydroxide[Cr(OH)3]. The supernatant from settling tank is further filtered for removal of Fe3+ in form of suspended solids.

Stage-I

1. If water contains chromates[CrO4]2- [CrO4]2- + 6Fe2+ + 8H+ Cr3+ + 6Fe3+ + 4H2O

2. Cr2O7 2- + 6Fe 2+ +14(H+) 2Cr3+ +6Fe3+ +7H2O

Stage-II

a. Cr3+ + 3NaOH Cr(OH)3 + 3Na+ b. Fe3+ + 3NaOH Fe(OH)3 + 3Na+

The Stock pile area runoff effluent (250m3/hr) will be collected in tank after passing through screen chamber and grit removal chamber and transferred into the flash Mixing tank-I by surface runoff Transfer pumps. Sulfuric acid/HCL given at the Flash Mixture tank-I and ferrous sulphate dosing is given to Flash Mixture Tank-II to enhance the conversion of Hexavalent Chromium(Cr+6) to Trivalent Chromium (Cr+3). Two nos. of Dosing tanks (1W+1S) to be provided for H2SO4 and same for FeSO4. Two (2) numbers of acid dosing pumps (1W+1S) and two nos. of FeSO4 dosing pumps to be provided with VFD motors to facilitate automatic control and regulation of dosing rate through PLC control system.


FIG:9 : EFFLUENT TREATMENT PLANT- ENSURING ZERO DISCHARGE

FEED PUMP (2 X 125 m3)

CLARIFLOCCULATOR

FILTER PRESS FEED (PUMP-2 NOS)

FILTER PRESS

(2NOS)

BAR SCREEN

EQUILISATION TANK

FLASH MIXTURES # 1 H2SO4 ACID

DOSING SYSTEM

FERRUS SULPHATE DOSING SYSTEM

POLY ELECTROLYTE

DOSING SYSTEM

NaOH DOSING SYSTEM

SLUDGE STORAGE TANK

CLEAR WATER STORAGE TANK

FILTER FEED

PUMP

FILTER WATER FOR DISPOSAL

DUAL MEDIA FILTERS

FLASH

MIXTURES # 2

FLASH MIXTURES # 3

SLUDGE FOR DISPOSAL


Effluent from Flash mixture Tank-II shall be received in flash Mixing Tank-III where NaOH and Polyelectrolyte shall be dosed. Two numbers of dosing tanks(1W+1S) to be provided for NaOH and same for Poly electrolyte. Two numbers of NaOH dosing pumps (1W+1S) to be provided with VFD motors to facilitate automatic control and regulation of dosing rate through PLC control system but two numbers of poly electrolyte dosing pumps will be provided with manual control since TSS load should not be fluctuating regular basis.FeSO4 dosing will be controlled through ORP analyser whereas H2SO4 and NaOH dosing will be controlled through pH analyser. Effluent from flash mixing shall be received in clariflocculator. After treatment in Clariflocculator the effluent will pass through automatic self cleaning Filters with complete stainless steel structure, high filtration area, long –lived filter elements, automatic back flushing system, easy installation and maintenance and other superior characteristics. Backwash waste water from backwashing of Rapid sand gravity filters will be sent back to runoff collection tank. Under flow of Clariflocculator will be collected into sludge holding tanks and this sludge will be pumped to PLC based Centrifuge for dewatering of sludge. De-watered sludge will be disposed off and filtrate waste water generated during dewatering will be transferred in gravity line to Ferrous Sulphate Mixing Tanks. Backwash waste water from backwashing of pressure sand filters will be sent back to runoff collection Tank. Under flow of Clariflocculator will be collected into the sludge holding tanks and this sludge will be pumped to filter press by pumps for dewatering of sludge. The sludge are removed from the bottom as dewatered solids(“cake”).The liquid effluent is discharged from the feed end. De-watered sludge will be disposed off and filtrate waste water generated during de-watering will be transferred in gravity line to Ferrous Sulphate Mixing Tanks. B. BENCH FORMATION & STABILIZATION

The lease is comprising of 2 ore bands, Band-1 (Quarry-1) Band-VI(Quarry-2). Band – I (Band – I / Quarry – 1) No mining is continuing in this band since 2012-13 as the floor of the regular open pit (quarry) has reached Ultimate Pit Limit due to constraints of lease boundary, though ore below in dip direction continues .Well developed drainage system with effective toe drains are being maintained in the said quarry and de-silting of the drains all along the quarry are regularly carried out. M/s JSL is having proposals for development and production from this quarry on a joint development programme from the adjacent mine of M/S BAL. The existing and proposed bench parameters & quarry design are given below. Band – VI (Quarry – 2) The mining in the lease area is being carried out by opencast method and fully mechanized means. Drilling and blasting is being carried out to disintegrate the hard ore and associated rock. At present the working bench is at 150 mRL and is in operation in the insitu zone,


extending over a maximum working length of 306 m in E /W and 334 m in N/Sdirection following the southern boundary of the lease with top RL at 302 m in south and bottom RL at 150 m. The dimension of the present quarry is around 379 m long and 305 m wide. i. Salient features of the existing mining methods are given below :

Sl.No Particulars Band-I (Quarry-1) Band VI (Quarry-2)

1 Method of Mining Opencast , category : A-FM. Opencast , category : A-FM.

2 Type of ore Friable Chromite ore with intermediate waste and overburden comprising of laterite, silicified chert and ultramafics etc.

Lumpy Chromite ore with intermediate waste and overburden comprising of Qurtzite and ultramafics etc.

3 Means of raising Excavator and dumper combination.

Excavator and dumper combination.

4 Bench height and width Height of the benches are 8 m each with width 12 m.

Height of the benches are 8 m each with width 12 m.

5 Overall slope angle < 30O < 30O

6 Number of ramps Two (2) ramps in Q-1 Four (4) ramps in Q-2

7 Nature of overburden / waste

Limonite, laterite, silicified chert ultramafics, soft serpentinite and hard serpentinite.

Hard consisting of Quartzite, silicified chert, ultramafics, Hard Serpentinite.

TABLE : 2 : SALIENT FEATURES OF EXISTING CHROMITE MINING METHODS

The different design parameters of opencast working of quarry - 1 shall be as below during the scheme period 2017-18 :

Parameters Existing Quarry End of 2017-18

TOP mRL 160 160

Bottom mRL 57 57

Height of bench 8 8

Width of bench 12 mt above 12 mt above

Bench slope 750 to 800 750 to 800

No of bench 13 13

Overall pit slope 280 to 300 280 to 300

Haul road Gradient 1:16 1:16

No of ramp 2 1

Drain Dimension 1 m x 0.5 m 1 m x 0.5 m

Barrier Dimension 1.5 m x 1 m 1.5 m x 1 m


The different design parameters of opencast working of quarry – 2 shall be as below during the scheme period.

Parameters Existing Quarry End of 2017-18

TOP mRL 302 302

Bottom mRL 150 122

Working levels mRL 288 to 150 197 to 122

Height of bench 9 9

Width of bench 12mt above 12mt above

Bench slope 750 to 800 750 to 800

No of bench 17 20

Overall pit slope 280 to 300 280 to 300

Hul road Gradient 1:16 1:18

No of ramp 4 4

Drain Dimension 1 m x 0.5 m 1 m x 0.5 m

Barrier Dimension 1.5 m x 1 m 1.5 m x 1 m

(ii) Slope stability study of both the Quarries Considering the steep nature of the pit design, M/s JSL had carried out a bench slope stability study of both the friable and lumpy mines (Qry-1 &2) for safe and scientific mining through Central Mining Research Institute (CMRI). The study has recommended the following slope angles for both the quarries.

In Qry-1, the 83 m high southern and northern slopes (top at 140 mRL & bottom at 57 mRL) can have 38º overall slope angle.

In Qry-2, the 160m high southern slope with pit bottom at 120 mRL and 65m high northern slope of the open pit may have an overall slope angle of 44º and 53º respectively.

In case the working is exclusively limited to top weathered material in the southern slope of Qry-2, the mining should be done with the norms of friable ore quarry i.e. 38º overall slope angle.

For safe and scientific mining, well developed drainage system with effective toe drains, pre split blasting (wherever applicable) of ultimate slope and slope monitoring system on a long term basis was recommended.

During the mining operation M/s JSL has maintained a slope angel of <300 with bench height and width kept at around 8m and 14m. Effective garland drains all around the existing pits and bench slopes to collect surface run off has been made and shall be regularly maintained to avoid any slope failure during mining operation. The bottom RLs of Qry-1 & Qry-2 are presently at 57 mRL & 150 mRL respectively and are planned to be worked at 22 mRL and 122 mRLs during the balance scheme period with bench slopes maintained at around 35 O in Qry-1 and 30O in Qry-2. M/s JSL is taking all precautions as advised in the CMRI report during the mining


operation. Presently we have started the study work for safe and economical mining through IIT Kharagpur. However in some areas the contact zone of chrome ore in quarry-1 is associated with loose serpentines as a host rock of chromite .During rainy season the contact loose serpentines are being washed out from chromite, causing some irregular shape of bench which is towards western side of quarry – 1 in the lease. But this does not show the collapse of any bench or result of any slope failure. After the rainy season is over the benches are shaped by excavator and stabilized by filling of some materials with proper dozing and grading IIT Kharagpur is already carrying out Pit Slope Stability studies. The measures proposed by them will be followed. The details will be submitted along with the EIA Report.


Point No 2: The Tiger Corridor is located at a distance of about 8.8 km for the mine lease

boundary, an authenticated map from CWLW should be submitted in this regard.

There is no Declared Tiger Corridor within 15 km radius of the Mine lease area.


Authenticated Map from Forest Department


However, we have submitted an application form to the statutory authorities to obtain the fresh

authenticated Map w.r.t Tiger Corridor. Since this takes some time we request the honourable

committee to consider and issue us the Terms of Reference

**************************

tailing management, bench report on · material by a roll crusher product to make it slurry with...

Documents