Induced crystallization of Pb2+ on smithsonite surface during sulfidation-xanthate flotation

Smithsonite is a common oxidized zinc ore , and its recovery has gained increasing attention to meet the high demand for zinc. Current methods to concentrate oxidized zinc ores are through sulfidation flotation or “sulfidation + metal + xanthate” flotation. However, such techniques are not sufficiently efficient for treating smithsonite. In this study, Pb(NO 3 ) 2 was used to pre-treat smithsonite as a crystallization inducer, and the mechanism of lead modification was studied through micro-flotation tests, adsorption measurements, contact angle measurements, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and TOF-SIMS analysis. The micro-flotation test results showed that the recovery of smithsonite after Pb 2+ pre-treatment increased from 80.3% to 85.3%. The comprehensive results of adsorption experiments, contact angle measurements, XRD and SEM analysis indicated that Pb 2+ adsorbed on the smithsonite surface and transformed portion of smithsonite into cerussite, increasing the active sites on the mineral surface for adsorption of S ions . The newly formed PbS after sulfidation had an effect of induced crystallization on subsequently formed PbS, increasing PbS species and making the surface more effective for xanthate flotation. ToF-SIMS was used to visualize the 3D distribution of Pb 2+ and S 2- adsorption, and it further proved that pre-treatment with Pb(NO 3 ) 2 enhanced the sulfidation process of smithsonite.