Caving method in Longwall where the coal seam thickness is more than 3m

1. LONGWALL TOP COAL CAVING
P SHASHIKANTH
16MT001042

2. LONGWALL TOP COAL CAVING
GENERAL INFORMATION
• It is the modified method of longwall mining system
• Yancoal introduced the Longwall Top Coal Caving (LTCC)
mining technology in Australia at its Austar mine in
2006.
• This method has been developed in china in more
recent years and is used there quite extensively and
successfully.
• Cavability is one of the most important parameter that
controls the applicability of the LTCC.

3. LONGWALL TOP COAL CAVING
Major difference between Traditional
longwall mining and LTCC
The existence of an additional rear conveyor belt
behind the powered supports, on which the caved
coal from the upper part of the seam is drawn by a
moveable flipper attached to the canopy at the rear
of the powered supports.

4. LONGWALL TOP COAL CAVING

5. LONGWALL TOP COAL CAVING
The Principle of Longwall Top Coal Caving(LTCC)
 Special type of longwall of mining
 Applicable to very thick seams(greater than 6m)
where good quality coal is being left because
currently conventional longwall equipment cannot
operate successfully beyond 6m mining height
 It uses a longwall set-up and natural forces to aid in
winning of coal
 Increased recovery for only an incremental additional
cost

6. LONGWALL TOP COAL CAVING

7. LONGWALL TOP COAL CAVING
The Cutting sequence
• The lower section of the seam is cut by the shearer
at a set height.
• Front Armoured Face Conveyor(AFC) transports the
coal out of the face.
• The system moves forward to the next cut.
• The coal left above the section cut by machine is
induced to cave.
• The coal falls onto the extended canopies

8. LONGWALL TOP COAL CAVING

9. LONGWALL TOP COAL CAVING

10. LONGWALL TOP COAL CAVING
• The sliding rear canopies are sequentially opened
then the coal falls through onto the rear mounted
Armoured Face Conveyor(AFC).
• The sliding rear canopies are opened and closed in a
controlled manner to ensure the conveyor is loaded
efficiently and to prevent stone being taken out
when all the coal has been recovered from a
particular section.
• Rear Armoured Face Conveyor(AFC) transports coal
out of the face.
• Then, the rear conveyor is pulled towards the roof
supports.

11. LONGWALL TOP COAL CAVING
• Final cavity will fill with caved stone as the coal is
drawn out.
• Front Conveyor is pushed forward to the next cut.

12. LONGWALL TOP COAL CAVING
Another variation of the Top Coal Caving use, where the
seam thickness is over 15m.
 The longwall faces are again developed. The top slice is
placed so that there is 5m of coal left above the
supports.
 This top slice(first longwall face) is advanced as an
ordinary longwall operation, leaving 5m of coal
overhead. The overhead coal is allowed to cave with the
roof.
 The second longwall face is then started off(6-
12months) later at the foot of the seam using the basic
Top Coal Caving(TCC) method.

13. LONGWALL TOP COAL CAVING

14. LONGWALL TOP COAL CAVING
ADVANTAGES
• High coal recovery.
• Operating cost reduction.
• High productivity.
• Less energy consumption.
DISADVANTAGES
• The high coal loss occuring during the production of
top coal, resulting in a significant decrease of coal
recovery.

15. THANK YOU