Room and pillar
Room and pillar is also known as bord and pillar is a mining system in which the mined material is taken out across a horizontal plane while leaving "pillars" of unscathed material to support the overstrain leaving open regions or "rooms" underground. It is normally utilized for fairly flat-lying deposits, like those that follow a meticulous stratum.
The room and pillar system is used in mining coal, iron and copper ores mainly when found as manto or blanket sediments, stone and aggregates, talc, soda ash and potash.
The key to the winning room and pillar mining is opting the optimum pillar size. If the pillars are so small the mine will fall down. If the pillars are so big then significant quantities of valuable material will be left behind reducing the profitability of the mine. The proportion of material mined differs relying on a lot of factors, comprising the material mined, height of the pillar, and roof circumstances; characteristic values are: stone and aggregates 75%, coal 60%, and potash 50%.
Room and Pillar mines are urbanized on a grid basis apart from where geological traits like faults need the habitual blueprint to be customized. The size of the pillars is found by calculation. The weight bearing capability of the material above and below the material being mined and the ability of the mined material itself will find the pillar size.
If one pillar fails and surrounding pillars are not capable to support the area before supported by the failed pillar they may in turn fail. This might result to the fall down of the whole mine. To avert this mine is divided up into areas or panels. Pillars called as barrier pillars disconnected the panels. The barrier pillars are considerably bigger than the "panel" pillars and are sized to let them to support a major portion of the panel and avert progressive disintegrate of the mine in the event failure of the panel pillars.