Selective flotation of chalcopyrite from galena using oxadiazole-2-thione collector: a combined quantum chemical and experimental study

5-methyl isobutylxanthate-1,3,4-oxadiazole-2-thione (MIXODT) was designed. • Ionic MIXODT exhibits enhanced electron-donating ability. • Stronger adsorption on chalcopyrite than galena was confirmed. • Cu–S/N orbital hybridization governs selective chemisorption. • Flotation tests agree well with theoretical predictions. To achieve highly selective separation of chalcopyrite (CuFeS 2 ) from galena (PbS), we introduced a xanthate ester group into the 1,3,4-oxadiazole-2-thione skeleton based on a synergistic coordination design strategy and synthesized a collector, 5-isobutyl xanthate methyl ester-1,3,4-oxadiazole-2-thione (MIXODT), with 5-heptyl-1,3,4-oxadiazole-2-thione (HPODT) lacking this group as a control. Density functional theory (DFT) calculations   revealed   that the ionized form (MIXODT − ) is the predominant reactive species. MIXODT⁻   exhibited   significantly higher adsorption energy on the chalcopyrite (0 0 1) surface than on the galena (1 0 0) surface, and   outperformed   HPODT − . Density of states (DOS) and charge analysis   revealed   that MIXODT⁻   formed   multi-site Cu–S/Cu–N coordination bonds with surface Cu atoms through S and N active sites, leading to pronounced orbital hybridization and electron transfer, while only weak interactions   occurred   at Pb sites. Flotation experiments   confirmed   this selective interfacial bonding and   achieved   a distinct “high Cu, low Pb” separation window under low-alkaline conditions. The core innovation of this work lies in the multi-site synergistic coordination mechanism at the interface, which establishes an inherent link among molecular design, interfacial coordination chemistry, and selective flotation behavior, providing theoretical guidance for the rational design of collectors for copper-lead sulfide ores. Combining quantum chemical calculations with flotation experiments, this work systematically elucidated the multi-site coordination mechanism and selective flotation behavior of oxadiazole-2-thione-based collectors in chalcopyrite-galena separation. Download: Download high-res image (132KB) Download: Download full-size image