Abstract: Based on floatability characteristic of chalcopyrite and galena in CMC，aluminum sulfate or these two combined suppression system，effect of lead inhibition and copper flotation by aluminum sulfate+CMC in flotation process of a Cu-Pb mixed concentrate from Binzhou was studied. And then，the influence of aluminum sulfate to the absorption of Z-200 on the surface of chalcopyrite and galena was analyzed. The results showed that CMC，aluminum sulfate and these two combined reagents all increased the floatable difference of chalcopyrite and galena. The separation of copper-lead mixed concentrate can be realized with lower cost，less pollution and higher efficiency by firstly adding aluminum sulfate and then CMC. Hence，aluminum sulfate+CMC is recommended as new-type Pb depressant in copper-lead separation.

Key words: Chalcopyrite, Galena, Separation by flotation, Carboxymethyl cellulose, Aluminum sulfate, Combined depressant