Selective Flotation of Chalcopyrite from Pyrite Using 1,3,4-Thiadiazole-2-Thiol Collectors Under Low-Alkalinity Conditions

Conventional high-alkalinity processes for chalcopyrite–pyrite separation suffer from high reagent consumption and environmental issues, underscoring the need for efficient, low-alkalinity alternatives. Herein, we report the design of a novel series of 1,3,4-thiadiazole-2-thiol collectors (CSC-5, CSC-6, and CSC-7) based on a 1,3,4-thiadiazole functional core with various hydrophobic chains. The performance was evaluated through single-mineral, mixed-mineral, and run-of-mine ore flotation tests under mild alkaline conditions. The CSC collectors achieved high chalcopyrite recoveries (89.5–98.3 %) while effectively suppressing pyrite recovery (37.8–38.9 %), outperforming conventional collectors (EX, ADD, Z‑200) in selectivity. Surface characterization via Atomic Force Microscopy (AFM) and contact angle measurements confirmed selective adsorption and enhanced hydrophobicity exclusively on chalcopyrite. Density functional theory (DFT) calculations elucidated the underlying mechanism: strong chelation of CSC‑7 with iron sites on chalcopyrite, contrasted by weak interaction with pyrite, further stabilized by co‑adsorbed Na⁺ counterions. Our work provides a rational design strategy for high-performance collectors, paving the way toward efficient and environmentally sustainable separation of copper–iron sulfide ores.