在加拿大耐火材料公司凯洛玛矿的菱镁石开采中,一次井下大爆破就破碎了150,000吨矿石。采场中央大矿柱的爆破,完成了135米水平以上矿石的初次破碎,该矿房的采准工作是在1959年开始的。从采区内的分段巷道钻凿扇形深孔房柱法是加拿大耐火材料公司常使用的一种采矿法。在矿柱被爆破之前,矿房的两盘都为矿柱所支护,因而此种采矿方法的初次爆破成本低,由围岩引起的贫化小。由于矿工经常在能够控制不稳定岩石的相当小的分段巷道中作业,因此也保证了安全工作条件。 In a magnesite mining at the Canadian Cairua mine in Refractory, Canada, a major downhole blast destroyed 150,000 tonnes of ore. The blasting of large ore pillars in the stope of the stope completed the initial crushing of the ore above 135 meters. The mining and mining work was started in 1959. Segmenting tunnels from the section of a mining area is a commonly used mining method used by Canadian refractories. Prior to the blasting of the pillars, both mines of the mines were supported by pillars and the initial blasting cost of such mining methods was low and the depletion caused by the surrounding rock was small. As miners often operate in relatively small, segmented tunnels that can control unstable rocks, safe working conditions are also guaranteed.