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在国内外的采矿业中,随着开采技术水平的不断提高和开采设备的大型化;随着工农业的发展,对矿物原料的需求量日益增多,露天开采的比重也日益增大。就磷矿来说,国外露天开采比重达到80％以上,其中美国为97％以上,苏联不到80％。我国的磷矿、硫铁矿、石灰石矿、蛇纹石矿等化学矿的露天开采量约占总产量的42.6％。根据七五期间
In the mining industry at home and abroad, with the continuous improvement of mining technology and the large-scale production of mining equipment, with the development of industry and agriculture, the demand for mineral raw materials is increasing day by day, and the proportion of open-pit mining is also increasing day by day. For phosphate rock, the proportion of open-air mining in foreign countries reached more than 80%, of which more than 97% in the United States, the Soviet Union less than 80%. China’s phosphate rock, pyrite, limestone, serpentine and other chemical ore open-pit mining accounts for about 42.6% of the total output. According to the seventh period