Utilization of trisodium phosphate to eliminate the adverse effect of Mg2+ on the flotation of pyrite

Abstract

In this study, the effect of Mg2+ on the flotation of pyrite was systematically studied. Micro-flotation results showed that Mg2+ could significantly depress the flotation of pyrite at pH 10. As for the interaction mechanism, solution chemistry calculations, zeta potential measurements and adsorption studies indicated that the formation of Mg(OH)2 precipitates (due to hydrolysis of Mg2+) were positively charged, which would be adsorbed on the negatively charged pyrite surface, thereby preventing the adsorption of potassium butyl xanthate (PBX). In addition, scanning electron microscopy (SEM) tests, fourier transform infrared (FTIR) spectroscopy studies and X-ray photoelectron spectroscopy (XPS) analysis positively confirmed the presence of Mg(OH)2 precipitates on the pyrite surface. Interestingly, with the addition of trisodium phosphate (TSP), Mg(OH)2 precipitates were replaced by negatively charged Mg3(PO4)2, which would be desorbed from the pyrite surface due to electrostatic repulsion. In this way, Mg(OH)2 precipitates were removed from the pyrite surface. Finally, the adsorption amount of PBX on pyrite was restored, as well as the flotation recovery.