Temperature impact on xanthate adsorption and microflotation of galena, sphalerite, and pyrite

• Temperature effect on the flotation of galena, sphalerite and pyrite were investigated. • The microflotation yields corresponded well with the inverse gas chromatography surface energy results. • Adsorption kinetics of sodium isopropyl xanthate was heavily controlled by pH, temperature, and copper sulfate concentration. • Lower recovery of sphalerite at higher temperatures may be explained by the formation of calcium carbonate precipitates. • Lower recoveries at lower temperatures may be explained by a shift in the xanthate – oxy-complexes equilibrium. Selective flotation of lead–zinc ores is a process with many variables and a delicate balance of external (such as temperature) and internal factors (reagent concentrations, surface alterations). The purpose of this study is to explore flotation selectivity issues arising from changes in flotation pulp temperature. A deeper understanding of these issues can help to clarify industrial scale flotation discrepancies observed at different temperatures. Therefore, this paper provides insight into potential theoretical contributors to this balance, as well as assesses their affinity to temperature changes. These theoretical calculations assist in explaining observed variations in adsorption and microflotation results with temperature. Other statistically significant parameters influencing adsorption performance included xanthate concentration, copper sulfate dosage, and pH. Adsorption selectivity calculations were performed on individual mineral responses, which give insights into potential trends in the separation of galena, sphalerite, and pyrite. Adsorption results also confirmed current perceptions of the adsorption mechanism of dextrin. It has been shown that xanthate adsorption had the highest performance for galena among the three tested minerals. Scanning electron microscopy and EDS results allowed the extrapolation of a potential mechanism contributing to sphalerite depression at 45 °C. Inverse gas chromatography provided surface energy heterogeneity maps of the minerals. Surface energy values were generally in line with microflotation performance. The highest surface energy heterogeneity was observed for galena at 5 °C and for sphalerite at 45 °C. The role and variations in dissolved oxygen and lime dosages with temperature were also discussed with regard to flotation performance.