difficult separation coal [矿业] 难选煤

dense-medium separation coal 重介选煤

coal pneumatic separation [矿业] 风力选煤

underground coal separation 井下选煤

fine coal separation 细粒煤分选

steam coal separation 动力煤分选

coal separation 煤泥分选

dry coal separation 干法选煤

raw coal separation 原煤分选

lump coal separation 造成块煤分选