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U/G vs O/C PRODUCTION• Over 4970 Mte coal is produced the world over• 60% of world coal production comes from underground mines Country UG OC USA 33 % 67 % China (approx) 85 % 15 % India (10-11) 15 % 85% Australia 20% 80%
U/G production & productivity• The declining trend in underground production is continuing• Use of mechanization (SDL/LHD) and reduction of manpower has improved the productivity but failed in improving production
Reserve• India has around 253 Bt of reserve i.e. about 10% of the world reserve – Depth wise reserve • 0 to 300m : 155 Bt • 300 to 600m : 66 Bt • 600 to 1200m : 19 Bt• Presently nearly all the mines are upto 300m depth only• Around 90 Bt coal i.e 38% untouched virgin reserve lies at a depth of more than 300m which can be mined by u/g mining only.• Hence the future production of coal will be from underground mining.
Improving U/G production and productivity• How to improve production and productivity of u/g mines – Mechanise loading, drilling and conveying system – Increase depillaring – Provide man riding system – Introduce mass production technology, do away with blasting technology where feasible – Encourage indigenous manufacturing of mass production equipment – Introduce all man all job – Introduce contract labour to overcome shortage – Automation of the systems as far as possible
Mass Production Technology• For survival of underground mines, it should compete with opencast mines• This is possible by improving the production and OMS of U/G mines• Even though CIL overall OMS has improved from 1.86 (1997) to 3.55 (2007) the share of manpower cost has remained around 45 to 50%.• EMS today is around Rs 850, hence low productivity will not do.• Adoption of mass production technology is a must
Continuous Miner Continuous miner is a mass production technology for underground mining that can be used in bord & pillar (room & pillar) rib pillar and shortwall methods. Continuous miner has been adopted for bord & pillar method in Anjan Hills/ NCPH of SECL and in Tandsi Mine of WCL. Adoption in Jhanjra, ECL is under process. SECL has achieved annual production of more than 0.5 MTe with CM About 20 more mines have been identified for introduction of CM in future
Suitable conditions for CMThough equipments are manufactured tosuit wide range of conditions, some of thelimitations of its use are as follows. Seam thickness: 1.8m to 5m Seam gradient: 1 in 8 or flatter Floor rock: Hard and dry floor condition desirable for efficient operation Roof condition: Bad roof condition adversely affects system performance. (RMR at NCPH Old – 55; Tandsi – 36)
Broad specifications of equipments being used in CIL Continuous Miner - 12CM15-10D (Crawler- mounted) Operating height range: 2.28 – 4.6m; Cutting drum width: 3.3m; Total motor power: 564 kW Shuttle Cars - 10SC32B (Tyre-mounted) Safe carrying capacity: 13.6 t (It carries 8t of coal in NCPH); Cable reel capacity: 200m; Total motor power: 107 kW Quad Bolter – RT117 (Crawler-mounted) Minimum tram height: 2.15m; Operating height range: 2.4 – 4.775m; No. of bolters: 4 (2 per platform); Motor power: 112 kW Feeder-breaker – BF-14B-3-7C (Crawler-mounted) Throughput: 250 & 500 tph; Breaker Motor: 112 kW Load-Haul-Dump (LHD) (Tyre-mounted) Load-centre (Trolley-mounted)
Working system of CM In this technology, mining takes place by “Place Changing System”. Five heading panel is optimum. Gallery width should be minimum 5m The continuous miner cuts and load coal to shuttle car at a ‘place’. For developing full width of gallery, CM cuts in two passes at a place. The shuttle car hauls the load to the feeder-breaker. The feeder-breaker feeds sized coal to the gate-belt conveyor at a consistent rate when coal is dumped on it. After completing a cut of desired length (cut-out length), the CM moves out of the ‘place’ and the roof-bolter moves in for roof bolting. Resin capsule is used. Same sequence of operation is repeated at another ‘place’.
Safety factor as per squat formula• As per squat formula the pillars are over sized as per regulation• Safety factor of 2 and above is considered safe Depth As per 2.5m Ht. 5m Ht Reg Safety factor > 60m 19.5 7.4 4.3 60m -90m 21.0 5.5 3.0 90m – 150m 25.5 4.6 2.1
BLEEDER HEADINGS GAS BLEED LARGE STOCKS VENTILATION BREAKER PROPS NEXT FENDER 15 NEXT SPLIT 16 CONVEYOR ROADRETURN ROAD WONGAWALLI BLOCK
Factors affecting production capacity for a given set of equipments Size of pillars (centre-to-centre) Width of galleries, splits, and slices Height of extraction Number of pillars in a row Maximum permissible cut-out length Bolting grid size/ No. of bolts per m2 Time cycle of different equipment Specific gravity of coal Recovery percentage Available and utilisation hours of the system Sub-system capacity, spares, maintenance, trained manpower, etc.
World Scenario of CM CM as % of Best annual Aver. annualCountry total U/G production production production from a mine from a mineSouth 92% 1.44 MTY 0.78 MTYAfricaUSA 49% 1.32 MTY 0.86 MTYChina 2.6 MTY 0.36 MTYAustralia 15% 0.72 MTY 0.48 MTY
Average production in USA with CM Seam Thickness (m) Average Production per shift (Short Te) 2.5 750 3.0 835 3.5 920 4.0 1005
AVERAGE TIME DISTRIBUTION OF VARIOUS ACTIVITIES FOR A DAY (pillar 30m, gallery 5m) Time in Activity hr Hours 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 4Maintenance time 10.07 (8.44 Working of CM & SC cut) Marching,Shifting & 2.61 Positioning time CM Shifting of Feeder- 2.5 breaker, belt 1.82 Break down of CM Electrical fault, outbye transport BD, 3 power failure etc 13.03 Bolting time of RB 2.57 Marching time of RB 0.14 Break down of RB LAG TIME
Further advancement (CM)• Continuous miner with satellite bolter• Flexible tram conveyor• Mobile breaker line support• Predictive maintenance
Man Riding• Man-riding systems on tracks: – By rope haulage: – By locomotive (Trolley-wire/ Battery operated/ Diesel operated)• Trackless man-riding systems: – Belt conveyor – Chairlift: – Free-steered vehicle