it is a mining method by which we can extract the coal of highwall, when the open cast reaches to its limiting point, by the help of this method we can extract the locked up coal.

1. Extraction of Locked Up Coal by
Alternate Mining Method in India
Presented By
Arnab Show & Anurag Jha
HIGHWALL MINING

2. Extraction of Locked Up Coal by Alternate Mining Method

3. Extraction of Locked Up Coal by Alternate Mining Method
What is Locked up Coal?
- Coal which is not possible to extract economically by
conventional mining method
1. Opencast
2. Underground
3. Longwall

4. Extraction of Locked Up Coal by Alternate Mining Method
Total Coal Reserve 239.50 Billion Tonne
Proved 49%
indicated
40%
20% of Total Reserve

5. Extraction of Locked Up Coal by Alternate Mining Method
Total Coal Reserve 239.50 Billion Tonne
Proved 49%
indicated
40%
Highwall
20% of Total Reserve

6. • Cannot be Economically extracted by conventional Mining Methods
• Has a huge risk of working in terms of safety.
• Stripping ratio is very poor
• Uneconomic to imply heavy machinery
• Grade of coal may be unsatisfactory in terms of investment.
Thus to deal with all this issues, Highwall Mining Method is Adopted

7. What is Highwall ?
• Highwall mining is a remote controlled mining method which extracts coal
from the base of an exposed highwall via a series of parallel entries driven
to a significant depth within the coal horizon.

8. • Most Safe Method
• Highwall Production Potential
• Higher Productivity
• Conservation of coal
• Mobility

9. METHOD OF MINING
 Generally four types of method are being practiced for creating highwall mining
under different mining conditions.
i) Contour Mining
ii) Trench Mining
iii) Bench Mining
iv) Highwall Mining Method
The technology is quite flexible depending upon the availability of the coal block.

10. CONTOUR MINING
 In a mountainous area, the highwall mining system can follow
a coal seam along the side of the hill.

11. TRENCH MINING
 The unit mines coal from both sides of a purpose-prepared trench;
this mining method is used when an open pit is not an option.

12. BENCH MINING
 Mining by preparation of benches in each seam for multi-seam
working is called bench mining.
 For working multi seam deposit, a bench is prepared in the
top seam and mining operation is taken top downwards.
 Highwall mining can also be done by preparation of
benches from bottom upwards but there is a possibility of
damages to the coal of upper seams if there is any failure
of web pillars at the bottom seams.

13. Bench Mining

14. Mine Floor Coal

15. Highwall Mine Seam

16. Highwall Mine Seam

17. Blast 2nd Bench

18. Blast 2nd Bench

19. Mine Floor Coal Bench 2

20. Highwall Mine Seam 2

21. Highwall Mine Seam 2

22. Strip Seam 3

23. Strip Seam 3

24. Strip Seam 3

25. Strip Seam 3

26. Strip Seam 3

27. Ready!

28. HIGHWALL MINING METHOD
 When the open pit mining has reached beyond the stripping ratio, the
coal Highwall can be taken out economically and safely by this
method.
.

29. DIFFERENT METHODS

30. HIGHWALL MINER MACHINE
 Miniature form of the continuous miner
 Operates at the highwall face and sits at the pit bottom
 The total operation from coal cutting to despatch of coal is done by the single machine
 Remotely controlled
 Minimum manpower of only 3-4 persons

31. PARTS OF A HIGHWALL MINER
 Base Unit
 Reels and Chains
 Push beams
 Cutter module
 Controls
 Anchoring
 Right angle conveyor
 Generator

32. HEALTH AND ENVIRONMENT
MONITORING

33. VENTILATION
 No man will be inside the hole
 Ventilation is not required normally
 Possibility of accumulation of methane cannot be
avoided when the seam is highly gassy

34. PROTECTION AGAINST METHANE
CONCENTRATION
 Continuous monitoring of the methane by DGMS
approved methane Sensors
 Intrinsically safe
 Methane sensor device interlocked with PLC control
system

35. PROTECTION AGAINST METHANE
CONCENTRATION
Power to UG will be “ON” only if:
 The Methane sensor is “ON”
 Working properly
 Methane level is below 1.25%

36. PROTECTION AGAINST METHANE
CONCENTRATION
When Methane level:
=0.8% Operator get audio-visual alarm
>1.25% U/G part of the machine will be powered “OFF”
In case methane sensor switched off or is in fault mode all electrical
power sources including signal & control will be shut off (fail safe)

37. COAL DUST SUPPRESSION
Water spraying on the cutter head – at a flow rate of
19 litre per minute at a pressure of approx 20 Bar.
It is interlocked with power supply to the cutter head

38. LIMITATION OF HIGHWALL
MINING TECHNOLOGY
 Flat seams -5 to 12 degree
 Seams free from geological disturbances
 Seam thickness between 0.8m to 1.5m
 Strong roof and floor
 Moderate make of water

39. SUPPORT

40. WEB AND BARRIER PILLAR
 Web pillars ensure support of OB
 Barrier pillars prevents Cascading Collapse
 Barrier pillar typically every 10-20 drives

42. CONCLUSION
 Highwall is most promising in India
 According to the present scenario of coal mines in India,
 Our 80% coal is produced by Opencast nowadays
 Most of the opencast mine will reach to its limiting value in 10-20 years
 Number of locked up seam will increase in future
 Highwall is most promising in India
 Introduced by Coal India in Singareni (SCCL)
 Adaptation is gradually increasing in other subsidiaries of Coal India