前言由于世界各地能源紧张和冶金、化学及合成燃料对煤炭的需要,煤炭的需要量急速增加,但是,目前的煤炭不能全部入选,入选量仅占世界煤产量的50%左右,这一问题值得注视。煤炭入选量将随煤产量的增加而加大,其理由为: 1、优质煤层枯竭, 2、机械化开采,增加了煤中的杂质; 3、煤中含有杂物,提高了运输 Preface Due to the energy shortage in all parts of the world and the demand of coal for metallurgy, chemical and synthetic fuels, the demand of coal rapidly increases. However, the current coal can not be selected for all, and the selected amount accounts for only about 50% of the world’s coal output. Watch The amount of coal selected will increase with the increase of coal production for the following reasons: 1, the depletion of high-quality coal seam, 2, mechanized mining, increasing the impurities in coal; 3, the coal contains debris to improve transport