The effect of copper ions on the surface chemistry of galena in near-neutral and alkaline solution

Abstract

In the process of flotation separation of copper-lead sulfide ores, the adsorption of copper ions on the galena surface often occurs, which poses a significant challenge in the separation of copper and lead. The adsorption mechanism of copper ions on the galena surface and its impact on the adsorption of the collectors (i.e., sodium diethyldithiocarbamate (NaDDTC) and sodium ethyl xanthate (NaEX)) at different pH levels (6.5, 9.5, and 12.5) with a copper ions coverage of 0.14 pseudo-monolayers, were studied using zeta potential measurements, inductively coupled plasma-optical emission spectrometry (ICP-OES), ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The obtained results showed that copper ions were primarily bonded to the S sites on the galena surface, forming Cu(I) sulfides, which could subsequently react with NaDDTC and NaEX to form cuprous diethyldithiocarbamate and cuprous xanthate, respectively. It was observed that the presence of copper ions affects the adsorption capacity of the collectors on the galena surface, depending on the type of collectors and the solution pH. Furthermore, the reactivity of the collectors with Pb sites on the galena surface may be reduced in the presence of copper ions.