在过去一段时间里,实际上所有矿山均为脉状地下开采。其重要性之相对降低是由于发展了大型挖掘设备,过去几十年的大多数年度中,大规模露天开采在金属价格低廉的情况下,仍有很好的经济效益。因而一些大公司不愿意经营开采费用高的小型地下矿 In the past period of time, virtually all mines were pulsed underground. The relative reduction in importance is due to the development of large-scale excavation equipment. In most of the past decades, large-scale open pit mining still has good economic benefits in the case of low metal prices. As a result, some big companies are reluctant to run small underground mines that are expensive to mine