Synergistic chemical bonding and hydrogen bonding interactions enable efficient collection for non-activated ZnSO4-depressed sphalerite by 2-ethylhexyl thioglycolate

Long-term upward trend of international copper prices pushes up sphalerite flotation operational costs, making the development of copper-free collectors an urgent demand for efficient sphalerite recovery. In the present study, the potential of 2-ethylhexyl thioglycolate (ET) as a collector reagent for non-activated ZnSO 4 -depressed sphalerite and its adsorption mechanism are evaluated by micro-flotation tests, multiple characterizations and DFT simulations. Micro-flotation tests confirm that ET can efficiently recover non-activated depressed sphalerite under high-alkalinity conditions, demonstrating improved floatability compared with the SBX collector. Surface physicochemical analyses reveal that the surface composition of depressed sphalerite evolves from hydrophilic inorganic species to hydrophobic organic components after ET adsorption. Combined with XPS analysis and theoretical simulations, it is revealed that the strong adsorption affinity of ET toward depressed sphalerite stems from synergistic adsorption mechanism, in which sulfhydryl groups coordinate with surface Zn sites and ester oxygen forms hydrogen bonds with –OH groups to build stable adsorption configurations. This work establishes a molecular-scale screening and design strategy for high-efficiency collectors of non-activated depressed sphalerite based on specific chemical bonding and hydrogen bonding interactions, and provides theoretical insights into the development of collectors with multiple active sites.