What is Pillaring in coal mining?

Mining that uses continuous-mining machines to cut into coal seams leaves behind pillars, or columns, of coal, to help support the mine roof and control the flow of air. Retreat mining’s goal is to recover as much coal as possible by pulling those pillars from areas that already have been extensively mined.

What is pillar and stall?

pillar and stall (bord and pillar, room and pillar; in Scotland: stoop and room) Method of mining in which large chambers are excavated, leaving pillars of ore, rock, or coal to support the roof.

What is Pillaring and retreat mining?

Retreat mining is the removal of pillars in the underground mining technique known as room and pillar mining. In the first phase of room and pillar mining, tunnels are advanced into the coal or ore body in a rectangular pattern resembling city streets.

What does stoping mean in mining?

Stoping, in mining engineering, the opening of large underground rooms, or stopes, by the excavation of ore. Stoping is practiced in underground mineral mining when the surrounding rock is strong enough to permit the drilling, blasting, and removal of ore without caving.

Why are there so many pillar failures in coal mines?

Random mine layout makes ventilation planning difficult, and if the pillars are too small, there is the risk of pillar failure. In coal mines, pillar failures are known as squeezes because the roof squeezes down, crushing the pillars.

How is coal extracted from a coal pillar?

Maximum possible coal is extracted form the pillars by driving galleries through them so that the portions of the pillars left in situ support the overlying strata. Caving is the general method adopted in majority of our mines at it does not involve the high cost of stowing arrangements.

What is the process of Depillaring in coal mines?

DEPILLARING It is the process of extraction of coal from pillars . It is also called pillar cutting or broken working. Fig 1-sequence of pillar extraction with diagonal line of face 5.

What’s the difference between pillar and pillar mining?

Room and pillar (variant of breast stoping), also called pillar and stall, is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars.