This document discusses continuous miners, an underground coal mining technology. Some key points: 1) Continuous miners use a mass production method and can be used for room and pillar and shortwall mining. Their use has increased production at some CIL mines in India to over 0.5 Mte annually. 2) Ideal conditions for continuous miners include seam thickness of 1.8-5m, gradients less than 1 in 8, and hard, dry floor conditions. Several CIL mines have been identified to introduce the technology. 3) The technology involves a continuous miner cutting coal which is loaded onto shuttle cars and transported to a feeder breaker. Roof bolting then occurs before the min

1. CONTINUOUS MINER
CHANDAN CHAMAN

2. 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%

3. 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

4. Technology wise production
Production (Mte)
Mining Technology
2001-02 2002-03 2003-04 2004-05 2005-06
Conventional B&P 22.16 19.54 17.02 15.50 13.74
Conventional LW 0.20 0.20 0.15 0.15 0.15
Special Method 0.28 0.20 0.23 0.15 0.35
Mechanised B&P 21.02 25.98 26.99 28.93 30.85
Mechanised LW 2.54 2.10 2.42 1.75 2.06
Continuous Miner 0.40 0.66 0.56 0.70
Total 46.20 48.42 47.47 47.04 47.85

5. 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.

6. 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

7. 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

8. 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

9. Suitable conditions for CM
Though equipments are manufactured to
suit wide range of conditions, some of the
limitations 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)

10. 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)

11. Continuous Miner

12. Shuttle Car

13. Quad Bolter

14. 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’.

15. 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

17. Typical Multi-Pass Continuous Miner
Operation

18. A typical cutting sequence for
development panel
5.0m 30.0m
19 15 20 21 26 23 27 25
11 14 12 16 13 22 17 24 18
25.0m
6 7 8 9 10
30.0m
25.0m
10m
1 2 3 4 5

20. A typical cutting sequence for
depillaring panel

21. 1 C
2
3
4
C
C
Outside Lifts Overall Cut Sequence

22. 8 7 6
C
1 3 5
9
13 10
4
14 11
15 2 12
C
C
Pocket and Wing Overall Cut Sequence

23. Twin Entry Development Layout
Continuous
Belt Feeder-Breaker Shuttle Car Miner
30 m
30 - 70 m

24. Rib Pillar

25. BLEEDER HEADINGS
GAS
BLEED
LARGE STOCKS
VENTILATION
BREAKER
PROPS
NEXT FENDER
15 NEXT SPLIT 16
CONVEYOR ROAD
RETURN ROAD
WONGAWALLI BLOCK

26. 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.

27. Daily production considering
utilization factor
Development:
Pillar width: 30m
Extraction Gallery width (m)
height (m) 5 5.5 6 6.5
2.5 1654 1679 1701 1720
3 1837 1895 1947 1992
3.5 1930 1985 2033 2075
4 2006 2058 2103 2143

28. Daily production considering
utilisation factor
Depillaring:
Extraction Gallery width (m)
height
(m) 5 5.5 6 6.5
2.5 2143 2054 1974 1887
3 2317 2231 2152 2066
3.5 2460 2377 2300 2216
4 2583 2500 2426 2344

29. World Scenario of CM
CM as % of Best annual Aver. annual
Country total U/G production production
production from a mine from a mine
South
92% 1.44 MTY 0.78 MTY
Africa
USA 49% 1.32 MTY 0.86 MTY
China 2.6 MTY 0.36 MTY
Australia 15% 0.72 MTY 0.48 MTY

30. 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

31. 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
4
Maintenance 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

32. Further advancement (CM)
• Continuous miner with satellite bolter
• Flexible tram conveyor
• Mobile breaker line support
• Predictive maintenance

33. Continuous miner with satellite bolter

34. Continuous miner with satellite bolter

35. 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

36. THANKS
chandanchaman@gmail.com