1. DRIVAGE OF INCLINES IN MANDLA NORTH COAL MINE of Jaiprakash Associates Limited, Noida by by M N Jha & M S Sandhu 1

2. COAL 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. 2

3. GENERAL 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. 3

4. COAL 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 HORIZONCOAL SEAM TOP SET 1Seam I B 2Seam I C 3Seam II 4Seam III B BOTTOM SET 5Seam IVA/A 2 6Seam VA/A 1 7Seam VB/B 1 4

5. METHOD 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

6. METHOD OF WORKING (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. 6

7. METHOD OF WORKING (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. 7

8. INCLINE 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. 8

9. INCLINE DRIVAGE (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

10. INCLINE DRIVAGE (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 10

11. INCLINE DRIVAGE (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 11

12. INCLINE DRIVAGE (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 12

13. INCLINE DRIVAGE (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 13

14. INCLINEDRIVAGE (Contd) INCLINE DRIVAGE (Contd)  BLASTING PATTERN 14

15. 15 INCLINEDRIVAGE (Contd) INCLINE DRIVAGE (Contd)  BLASTING PATTERN

16. INCLINEDRIVAGE (Contd) INCLINE DRIVAGE (Contd)  Time Study ActivityTotal Time (In minutes) Tramming05 Water connection15 Scaling (Dressing)20 Face Drilling52 Roof Drilling20 Roof bolting50 Water dis-connection15 Tramming07 Face charging60 Blasting10 Entry after blast20 Face clearance after blast30 Mucking(Blasting muck clearance)240 General work(Ducting, lighting etc)60 Total Time604 (Say 600 minutes) i.e 10 hours. 16

17. CONCLUSION  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. 17

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