Long wall mining is the most productive technology in the world,where one shearer is deployed in one mine for producing coal up to 1 million-3million tons per annum from a single face.The advantage of the system is that it has very low manpower requirement.It can work in very high gradient working and has the lowest cost of production mainly on the account of high output.This is also one of the safest mining operations.
In this system,the coal is developed by gate road on the both sides of the long wall and is recovered with shearer system with power pack support and coal evacuation system.
Long wall mining has its own disadvantages with context to the Indian mining industry.The following are some of them:
(i)The coal seams should be free of any geological disturbances and since Indian seams are highly geologically disturbed,deployment of such system fail;
(ii)It can a highly capital intensive technique;
(iii)It cannot be done without back filling with sand.A heave buildup structure and habitats on the surface make it impossible to work by this method.
In place of a typical long wall technology with face length of around 250 meters,a short face length of around 40-90meters is adopted in Balrampur Colliery of SECL.
The short wall technology is a smaller version of the long wall.This has a small wall for cutting (50-100meters)in place of more than 250 meters in conventional long wall.The capital cost is small.In smaller capacity short wall,the stowing can also be done to manage subsidence in case of structure buildup on the surface.