Spectroscopic investigation of sulphidation of zinc and lead carbonates

Abstract

The sulphidation of smithsonite (ZnCO₃) and cerussite (PbCO₃) mineral ores by Na₂S solutions has been studied by X-ray photoelectron spectroscopy and infrared spectroscopy. Results have shown that the surface of the two minerals is sulphidized in a different manner under similar experimental conditions. High Na₂S concentration (0.208 mmol cm^–3) and low temperature (20 °C) have been demonstrated to be the most effective conditions for obtaining a good sulphidation. Results have been interpreted considering the formation of compact and very thin film of ZnS (with a depth of 1–2 atomic layers) in the case of smithsonite and of a non-continuous porous layer of PbS for cerussite. On the latter, a higher amount of hydrated species has been detected after treatment and some dissolution of the mineral has occurred.