Depression mechanism of environment-friendly depressant dithiocarbamate chitosan in flotation separation of Cu-Zn sulfide

Abstract

The depressant performance and mechanism of dithiocarbamate chitosan (DTC-CTS) in flotation separation of chalcopyrite and sphalerite were investigated by micro-flotation experiment, UV–vis (UV–vis) spectrophotometer determination, time of flight secondary ion mass spectrometry (ToF-SIMS) test and local electrochemical impedance spectroscopy test (LEIS). The flotation results of Cu-Zn (1:1) mixed sulfide showed that chalcopyrite can be effectively separated from sphalerite using DTC-CTS as depressant and butyl xanthate as collector. The optimum conditions for flotation separation of chalcopyrite from the Cu-Zn sulfide were as follows: the dosage of DTC-CTS of 0.4 mg/L, butyl xanthate of 1 × 10−5 mol/L and flotation pH of 10. Copper concentrate with Cu grade of 31.93% and recovery of 85.97%, Zn grade of 4.82% and recovery of 4.18% can be obtained under the above conditions in the Cu-Zn sulfide flotation system. The results of ToF-SIMS showed that DTC-CTS can adsorb on both chalcopyrite and Cu-activated sphalerite surfaces, and the adsorption capacity on the two surfaces is roughly equivalent. UV–vis Spectrophotometric determination and LEIS results indicated that DTC-CTS strongly blocks the subsequent collector adsorption of butyl xanthate on sphalerite surface, but has little effect on the adsorption of butyl xanthate on chalcopyrite. Such difference of collector adsorption on chalcopyrite and sphalerite surfaces differs the surface hydrophobic and further results in the selective separation of chalcopyrite from Cu-Zn sulfide ore.