Abstract: To comprehensively recover valuable metals such as Cu and Ag from a zinc kiln slag in Gansu Province,flota tion tests were carried out.In view of the high carbon content in the zinc kiln slag that deteriorates Cu-Ag flotation,decarburiza tion flotation condition tests were firstly conducted.Subsequently,the effects of activator,collector and frother dosages on Cu-Ag flotation were systematically investigated,and the optimal flotation conditions were determined.Finally,the flotation flowsheet of "pre-decarburization,one rougher,three cleaning and two scavenging" was established.The results show that the contents of Cu,Ag and C in the zinc kiln slag are 1.38%,107.09 g/t and 16.90%,respectively,indicating that Cu and Ag have high re covery value,while the excessively high carbon content severely interferes with Cu-Ag flotation.Under the conditions of grind ing fineness of -0.074 mm accounting for 80%,decarburization collector (kerosene) dosage of 2 000 g/t and frother (2# oil) dosage of 400 g/t,the carbon removal rate (C recovery) reaches 90.04%.The optimal Cu-Ag roughing conditions are:activa tor sodium sulfide dosage of 600 g/t,collector combination of ammonium dibutyl dithiophosphate + butyl xanthate of 200+100 g/t,and frother 2# oil dosage of 300 g/t.Under the optimized conditions,a copper-silver mixed concentrate with Cu and Ag grades of 13.36% and 1 162.70 g/t is obtained through closed-circuit flotation,with Cu and Ag recoveries reaching 66.62% and 75.58%,respectively,achieving efficient comprehensive recovery of copper and silver resources from the zinc kiln slag.

Key words: zinc kiln slag,flotation,comprehensive recovery,decarburization