Utilizing 3-mercapto-1-propanesulfonic acid sodium salt as a selective depressant for the flotation separation of chalcopyrite from galena: An experimental and surface analysis study

The flotation separation of chalcopyrite and galena presents a significant challenge due to their similar floatability. This research explores the application of 3-mercapto-1-propanesulfonic acid sodium salt (MPS) as a selective depressant for galena to facilitate its separation from chalcopyrite. Micro-flotation assays on individual mineral samples demonstrated that MPS efficiently inhibited galena flotation with negligible impact on chalcopyrite recovery. In the flotation of artificially blended ore samples, under optimized parameters (initial pH of 5.5 and 40 mg/L MPS), a concentrate containing 30.02 % copper (Cu) and 11.05 % lead (Pb) was obtained. The recoveries of Cu and Pb were 92.02 % and 13.86 %, respectively, indicating successful separation. The investigation utilized a suite of surface characterization methods, encompassing atomic force microscopy (AFM), zeta potential measurements, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The findings suggest that MPS exhibited robust adsorption onto the galena surface, potentially via chemisorption, thereby generating a hydrophilic layer that impeded collector adsorption. However, MPS exhibited weak adsorption on chalcopyrite, maintaining its floatability. Density functional theory (DFT) calculations supported these findings. The findings demonstrated the thiol S of MPS undergoes chemisorption onto the galena surface via S–Pb bonding with surface lead atoms. This study provides a novel small-molecule depressant with high selectivity for the flotation separation of chalcopyrite and galena.