Metal ion mediated adsorption of dithiooxamide on chalcopyrite: Interfacial hydration and selective flotation copper-molybdenum separation

Copper ions promote selective dithiooxamide adsorption on chalcopyrite. • The adsorbed layer increases chalcopyrite hydration and suppresses flotation. • Molybdenite remains floatable, enabling low-dosage copper-molybdenum separation. Efficient separation of chalcopyrite and molybdenite remains challenging because both minerals exhibit high natural floatability, which limits the development of a stable flotation contrast in bulk Cu-Mo concentrates. Dithiooxamide (DTO) was used as an organic ligand to selectively depress chalcopyrite under near-neutral conditions. Single-mineral micro-flotation showed that, at pH 7 with 9 mg/L Cu 2 + and 8 mg/L DTO, chalcopyrite recovery decreased to 0.42%, whereas molybdenite recovery remained approximately 80%. When used individually, Cu 2+ and DTO yielded chalcopyrite recoveries of 83.42% and 69.31%, respectively, indicating that their combined use markedly enhanced chalcopyrite depression. For an artificial mixed mineral treated at pH 7 with 6 mg/L Cu 2+ and 8 mg/L DTO, the concentrate contained 44.95% Mo at 78.34% recovery. The corresponding Cu grade and recovery were 8.66% and 26.12%, respectively. Cu 2+ /DTO treatment reduced the chalcopyrite contact angle from 92.98° to 68.50° and increased its mean local impedance from 110149 to 162525 Ω. In contrast, the wettability and impedance of molybdenite changed only slightly. FTIR, SEM-EDS, and XPS analyses suggest that DTO-related species are preferentially enriched on chalcopyrite. These results are consistent with the formation of a polar interfacial layer that increases chalcopyrite hydrophilicity while exerting a limited effect on molybdenite. The findings provide an interfacial-chemistry basis for a low-alkalinity, low-dosage reagent scheme for Cu-Mo separation. Download: Download high-res image (261KB) Download: Download full-size image