Blasthole Stoping Mining Method

The low-cost, bulk method known as blasthole stoping suits large, regularly-shaped steeply dipping ore-bodies. The wall rock must be competent — the stope has to be able to stand open without support. It is also a convenient way to excavate large underground openings, such as crusher stations and storage bins.

Typically, a block of ore is prepared by driving sublevels through the ore-body at vertical intervals of about 20 meters (66 feet). Then a raise is made between sublevels, and opened across the width of the stope into a slot shape by successive blasts, providing an opening in which to blast the remainder of the ore in the stope. Blastholes are drilled in a fan-like pattern into the ore across the entire lace of the snipe. They are loaded with explosives and detonated to break into the slot raise. Broken ore is either removed by load-haul-dump machines from from drawpoints or by rail cars loaded by slushers.

Room-and-Pillar

In cases where the orehody is narrow and flat-lying, as is the case with many coal, potash, salt and Mississippi Valley-type lead/zinc deposits, a mining method known as room- and-pillar is often used, As the name suggests, ore is mined from large voids or rooms, and pillars of ore are left between the rooms to support the overlying strata. The ore pillars remain upon completion of mining and are not recovered.