Abstract: The characteristics of associated pyrite in Dachang Cassiterite Polymetallic Mine, Fankou Lead -zinc Mine and Wushan Copper Mine and the influence of pyrite depressed by CaO in butyl xanthate system were researched.The results show that associated pyrite in Dachang Cassiterite Polymetallic Mine, Fankou Lead-zinc Mine was p-type semiconductor, associated pyrite in Wushan Copper mine was n-type semiconductor.The order of sulphur-iron ratio of three kinds of pyrite was Dachang Cassiterite Polymetallic Mine＞Fankou Lead-zinc Mine＞Wushan Copper Mine.The order of crystal lattice constant was Dachang Cassiterite Polymetallic Mine＞Wushan Copper Mine＞Fankou Lead-zinc Mine.The floatability of three kinds of pyrite is mainly influenced by the semiconductor type and sulphur-iron ratio, the difficulty of pyrite depressed by CaO is mainly influenced by the crystal lattice constant.The associated pyrite with p-type semiconductor and major sulphur-iron ratio is easily floated.The pyrite with bigger crystal lattice constant is easier depressed by CaO.

Key words: Pyrite, Sulphur-iron ratio, Lattice constant, Semiconductor type, Floatability