Oxidative Depression of Arsenopyrite by Using Calcium Hypochlorite and Sodium Humate

Abstract

During smelting, arsenic in copper concentrates affects the product quality and causes environmental pollution. Removing arsenic minerals from copper concentrates requires environmental-friendly and cost-effective depressants for flotation separation. Ca(ClO)2 was combined with sodium humate (SH) to improve the flotation separation of chalcopyrite from arsenopyrite. Results of single-mineral flotation indicated that combined Ca(ClO)2 and SH significantly inhibited arsenopyrite and exerted a negligible effect on chalcopyrite. The arsenic content in copper concentrates significantly decreased from 63% to 11% in the absence of a depressant and in the presence of Ca(ClO)2 and SH, as proven by the mixed-mineral flotation results. SH can adsorb on both mineral surfaces as indicated by the zeta potential measurements and Fourier transform infrared spectroscopy. However, the presence of Ca(ClO)2 increased the adsorption of arsenopyrite compared with chalcopyrite. The arsenopyrite floatability depressed with the Ca(ClO)2 oxidation and subsequent SH adsorption, as verified by X-ray photoelectron spectroscopy. Results of flotation tests confirmed that the chalcopyrite surface was slightly oxidized, but it remained hydrophobic. The combination of depressants has the potential for industrial application.