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Room and pillar or pillar and stall is a variant of breast stoping.It is a mining system in which the mined material is extracted across a horizontal plane, creating horizontal arrays of rooms and pillars.
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. Pillars are left between tunnels to support the weight of the overburden. The first phase is ...
Room and pillar : Room and pillar mining is commonly done in flat or gently dipping bedded ore bodies. Pillars are left in place in a regular pattern while the rooms are mined out. In many room and pillar mines, the pillars are taken out starting at the farthest point from the stope access, allowing the roof to collapse and fill in the stope.
Room and pillar methods are well adapted to mechanization, and are used in deposits such as coal, potash, phosphate, salt, oil shale, and bedded uranium ores. Blast mining – An older practice of coal mining that uses explosives such as dynamite to break up the coal seam, after which the coal is gathered and loaded onto shuttle cars or ...
It has a grid of 16-foot-high (4.9 m), 40-foot-wide (12 m) tunnels separated by 25-foot-square (7.6 m) limestone pillars created by the room and pillar method of hard rock mining. [1] The complex contains almost 10.5 miles (16.9 km) of illuminated, paved roads and several miles of railroad track.
When the ore body is more or less horizontal, various forms of room and pillar stoping, cut and fill, [4] or longwall mining can take place. In steeply-dipping ore bodies, such as lodes of tin, the stopes become long narrow near-vertical spaces, which, if one reaches the surface is known as a gunnis or goffen. [1]
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Room and pillar mining often leads to retreat mining, in which supporting pillars are removed as miners retreat, allowing the room to cave in, thereby loosening more ore. Additional sub-surface mining methods include hard rock mining , bore hole mining, drift and fill mining, long hole slope mining, sub level caving, and block caving .