DRIVAGE OF INCLINES IN DRIVAGE OF INCLINES IN MANDLA NORTH COAL MANDLA NORTH COAL

MINEMINEof of

Jaiprakash Associates Limited, Noida Jaiprakash Associates Limited, Noida

by by

M N Jha & M N Jha & M S SandhuM S Sandhu1

COAL MINING SCENARIOCOAL MINING SCENARIO Coal mines were nationalized during 1971-73. 80% of coal production came from underground

mine during that era. Emphasis was given to develop Opencast mining to

meet rising demand. This trend continued with high level of mechanization

resulting into only 10% share of coal production from underground mines as of now.

Ministry of Coal identified Coal blocks for allocation to be developed scientifically through underground method only.

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GENERAL INFORMATIONGENERAL INFORMATION

Mandla North coal block with coal seams at a depth varying from 210 to 300 m was allotted to M/S Jaiprakash Associates Ltd.

It covers an area of 10.41 sq. km. Coal seams are highly disturbed with 29 faults in the

property. The major fault (F2A) with 100m throw divides the property in two parts.

The mine has been planned to extract 1.5 mtpa deploying 3 sets of Continuous Miner.

One set of inclines with one ventilation shaft are proposed to access coal seams.

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COAL SEAMSCOAL SEAMS Barakar formation contains 5 coal seams splitted in

to 19 workable/non-workable seams occurring at a depth varying from 173-350m.

The following distinct horizons formed by coal seams are found workable.

COAL HORIZON COAL SEAMTOP SET

1 Seam I B2 Seam I C3 Seam II4 Seam III B

BOTTOM SET5 Seam IVA/A2

6 Seam VA/A1

7 Seam VB/B1 4

METHOD OF WORKINGMETHOD OF WORKING It is planned to develop Seam IC initially having found in all 24

sectors with Gross reserve of 45.48 mt since Seam IA has not developed into workable thickness and Seam IB coalesced with Seam IC at various places.

Life span for extraction of IB/IC is estimated at 25 years @ 1.5 mtpa.

Extraction of II/IIIB shall be planned after a lapse of 5 years on completion of depillaring of the first panel of Seam IB/IC. This sequence will be followed for the remaining lower seams.

It has been decided to work this mine by Bord & Pillar method with deployment of Continuous Miner for driving Trunk headings along rise and dip of the property.

Panels comprising a set of 5 headings with cross connecting galleries will be opened on either side of the main trunk roadway for lateral development.

3 sets of Continuous Miners will be deployed to achieve the targeted Mine capacity of 1.5 mtpa. 5

METHOD OF WORKING METHOD OF WORKING (Contd)(Contd)

VENTILATION The proposed Mandla North Coal Mine has been

considered as Degree-II Gassy Mine for assessment and planning of ventilation requirements.

18000cum/minute of air is required to be produced by Mechanical system installed in Ventilation shaft.

3.3 kv, 350kw motors shall be installed. These figures has been arrived taking into account

all relevant DGMS requirements.

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METHOD OF WORKING METHOD OF WORKING (Contd)(Contd)EVACUATION OF COAL

Continuous Miner shall convey the coal into Shuttle cars through its bridge conveyor.

Loaded Shuttle car will discharge coal onto the feeder-breaker via coal hopper.

Coal will be discharged uniformly onto the gate belt conveyor from feeder breaker.

The gate belt in turn will discharge the coal onto the trunk belt conveyor and to bunker on the surface.

Mechanically covered trucks will carry the coal from bunker to Railway siding for loading into the railway wagons.

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INCLINE DRIVAGEINCLINE DRIVAGE

A single set of inclines measuring 5.2mX3.5m at a gradient of 1 in 4.5 are being driven in the centre of the property.

The above parameters will restrict the length of the inclines to 903mx2 with optimum level of efficiency both for evacuation of coal and man riding system.

The inclines will pass through Deccan Traps (495mx2) and Moturs (348mx2) before intersecting the coal bearing Barakars.

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INCLINE DRIVAGE INCLINE DRIVAGE (Contd)(Contd)

TECHNOLOGY Deployment of Road header - This option was not

considered because of its unsuitability in Basalt having hardness >8.

Drilling, blasting with combination of SDL and conveyor belt – The frequent shifting of Conveyor belt along with high level of maintenance makes this option unviable.

Deployment of Jumbo drill, SDL and 150kw haulage with 10t skips – This has been adopted being the most suitable for Indian condition and subsequently to be used for man riding. 9

INCLINE DRIVAGE INCLINE DRIVAGE (Contd)(Contd)

EQUIPMENTS-HAULAGE Haulage with man riding provision with following

specifications have been installed. Haulage rating – 150 kw Rope Speed – 2.2 to 2.5 m/sec Rope pull – 20 Tonnes in 1 in 4.5 gradient Rope diameter – 25 mm Motor RPM – 1000 Drum diameter – 1500 mm Rope length – 1200 m

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INCLINE DRIVAGE INCLINE DRIVAGE (Contd)(Contd)EQUIPMENTS-JUMBO DRILL

One Jumbo drill capable of drilling both face and roof holes in two inclines with following specifications has been deployed.

Make – Sandvik HL 510 Percussion pressure – 120-175 bar Rotation (max) – 175 bar Impact power – 16 kw Feed length – 3900mm+860mm Feed force – 9 Kn/120 bar Water pump – 1 x Water booster pump Length – 8015 mm Width – 1700 mm Height (without canopy) – 1800 mm

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INCLINE DRIVAGE INCLINE DRIVAGE (Contd)(Contd)EQUIPMENTS-SIDE DISCHARGE LOADER

Two SDLs to load the broken rock into the 10 t skip with following specifications.

Overall length – 5428 mm Height over canopy – 1850-2100 mm Ground clearance – 205 mm Bucket capacity – 0.66 cum (side tipping rock bucket) Gradient to be negotiated – 1 in 4.5 Track width (grouser pads) – 330 mm

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INCLINE DRIVAGE INCLINE DRIVAGE (Contd)(Contd)EQUIPMENTS-VENTILATION FAN

In order to get air flow of 8cum/sec at the face end of 900 m long drift, fans of 37.5 kw with following specifications are installed in respective inclines.

Fan Pressure – 3200 Pa RPM – 2950 Voltage – 415 V Rating of fan motor 37.5 kw

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INCLINEINCLINE DRIVAGEDRIVAGE (Contd)(Contd)BLASTING PATTERN

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INCLINEINCLINE DRIVAGEDRIVAGE (Contd)(Contd)

BLASTING PATTERN

INCLINEINCLINE DRIVAGEDRIVAGE (Contd)(Contd) Time Study

Activity Total Time (In minutes)Tramming 05

Water connection 15Scaling (Dressing) 20

Face Drilling 52Roof Drilling 20Roof bolting 50

Water dis-connection 15Tramming 07

Face charging 60Blasting 10

Entry after blast 20Face clearance after blast 30

Mucking(Blasting muck clearance) 240General work(Ducting, lighting etc) 60

Total Time 604 (Say 600 minutes) i.e 10 hours. 16

CONCLUSIONCONCLUSION

We expect to achieve a progress of 90m per month in each incline to touch coal seam within a time span of 10-12 months.

Continuous Miner will be deployed to drive trunk heading and for formation of panels.

3 set of Continuous Miner along with allied equipments shall be commissioned to achieve the target production of 1.5 mtpa.

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