Selective depression of chalcopyrite by sodium 3-mercapto-1-propanesulfonate for CuMo flotation separation: flotation performance and interfacial mechanism

Selective depression of chalcopyrite while preserving molybdenite floatability remains challenging. Conventional sulfur-containing depressants may oxidize readily, require high dosages, or depend on strong alkalinity, prompting the development of new selective reagents. Sodium 3-mercapto-1-propanesulfonate (MPS), containing thiol and sulfonate groups, was introduced as a selective chalcopyrite depressant. At pH 7 and 1.5 × 10 −5  mol L −1 MPS, the maximum recovery difference in single-mineral flotation reached 87.6 percentage points. In artificial mixed-mineral flotation, Cu recovery decreased to 7.28%, whereas Mo recovery remained at 91.16%, increasing the separation index from 1.28 to 11.49. Contact angle, SEM–EDS, and FTIR analyses indicated preferential retention of MPS-related species on chalcopyrite, together with interaction between thiol S and surface Cu sites and enhanced surface hydrophilicity associated with the sulfonate group. Under the electrochemical test conditions, MPS attenuated the anodic response and reduced the corrosion current density of chalcopyrite by approximately 40%, with little effect on molybdenite. DFT calculations further identified the Cu site on chalcopyrite (112) as more favorable for MPS adsorption than the Fe site (−100.96 versus −86.02 kJ mol −1 ), whereas the modelled adsorption configuration on molybdenite (001) was energetically unfavorable (+47.61 kJ mol −1 ). This study elucidates a selective depression mechanism involving preferential adsorption, increased surface hydrophilicity, and altered chalcopyrite redox behavior, while demonstrating the potential of MPS for near-neutral Cu Mo flotation separation. Download: Download high-res image (142KB) Download: Download full-size image