Recovery of zinc from cyanide tailings by flotation

•Sodium metabisulfite was used as an activator, which has never been reported.•Activation mechanisms of NaClO, H2O2 and CuSO4 have rarely been reported.•Zinc recovery exceeded 85% at the dosage of sodium metabisulfite 1.67 × 10−3 mol/L.•Activation mechanisms of these four activators were obtained.

The present research investigates sodium hypochlorite, hydrogen peroxide, sodium metabisulfite and copper sulfate as activators to lessen the depressant effect of cyanide. The results indicate that the zinc recovery exceeded 93%, 90%, 85% and 95% at the dosages: sodium hypochlorite 1.5 ml/L, hydrogen peroxide 2 ml/L, sodium metabisulfite 1.67 × 10−3 mol/L and copper sulfate 2 × 10−3 mol/L, respectively. According to the results of FTIR spectrum and zeta potential, it is suggested that the studied marmatite was depressed due to the adsorption of CN− on the surfaces of marmatite by chemical bonds, and moreover the afore enhanced activators can present ZnCNZnCN bonds on the surfaces of depressed marmatite by oxidation or ionic adsorption, respectively, and hence activate the depressed marmatite for flotation.