Abstract: The desired mineral liberation is the prerequisite for flotation. Finding out the inner relations among the ore fineness， the desired mineral liberation degree and its floatability， can provide guidance for the ore pretreatment before flotation. Thus taken copper ores of west ore body in Chambishi as a case， briefly discusses the relation between the mineral liberation degree and its floatability under different dissemination particle sizes， using mineral liberation analysis （MLA）. The results show that the main copper mineral is chalcopyrite （5.32%）， and the main gangue minerals are orthoclase， quartz and mica in Chambishi copper ore. In the ore， the copper mineral dissemination particle size is fine and uneven （10~500 μm）， and most of which are contiguous to quartz and feldspars， other fine particles are wrapped in coarse gangues， and there are a small number of sufficiently liberated chalcopyrite. When the ore is ground to 70% passing 74 μm， the free surface percentage of chalcopyrite raises from 60.88% to 78.14%， and the number of sufficiently liberated chalcopyrite significantly increases from 28.90% to 54.24%， while the distribution of chalcopyrite in coexistence does not change. In the flotation process， the optimum particle size is 18~100 μm， and the copper loss in the coarse particles is due to low liberation degree of copper minerals， but the loss in the fine particles is due to poor floatability.

Key words: Copper sulfide ore, MLA, Dissemination particle sizes, Mineral liberation degree, Floatability