Abstract: Slime content in a copper plant in Yunnan is very high，result in high copper grade in tailings.Tailings also has large amount of slime.Copper mainly exists in +37 μm fraction，with distribution rate of 66.07%，yield rate of -10 μm is 44.39%，while copper distribution is only 11.41%.Using cyclone desliming and decarburization pretreatment process，with hydrocyclone taper angle of 10°，grit mouth diameter of 3 mm，feeding pressure is 0.15 MPa，feeding concentration is 11%，grit with copper grade of 2.35% and recovery of 72.41% was obtained.Settling in copper mainly exists in form of secondary copper sulfide，oxidation rate of copper is above 30%.In order to determine reasonable settling separation process，copper sulfide and copper oxide in turn separation，and copper sulfide and copper oxide mixed separation principle process comparison was carried on.The results show that index of copper sulfide and copper oxide in turn separation process is better than that of copper sulfide and copper oxide mixed separation technique.At grinding fineness is 90% passing 0.074 mm，sodium silicate and sodium hexametaphosphate as the gangue inhibitors，sodium sulfide as the copper oxide mineral activator，butyl xanthate as collector，via three roughing-two cleaning-one scavenging closed circuit flotation process，copper concentrate with copper grade of 15.16% and yield recovery of 81.05% recovery to raw ore of 58.69% was obtained.

Key words: Copper tailing, Desliming by hydrocyclone, Preferential flotation