Desulfurization in high-sulfur bauxite with a novel thioether-containing hydroxamic acid: Flotation behavior and separation mechanism

Desulfurization is a critical problem in the efficient exploitation of high-sulfur bauxite resources. This study synthesized a novel thioether-containing hydroxamic acid (2-BTHA) by click-esterification-hydroxylamine oximation for flotation separation of pyrite from diaspore. DFT calculations indicated the functional groups of 2-BTHA were hydroxamate and thioether groups. Flotation results demonstrated 2-BTHA can effectively separate pyrite from diaspore under weak acidic conditions without adding vulcanizing agent. The UV-absorbance and surface energy tests explained introducing a thioether group improved the adsorption of Fe2+ on the collector, thus reducing its surface energy, hydrophilic index and free energy of bubble-mineral interaction, conducive to selective flotation. Zeta potential, infrared spectrum analyses and XPS further proved 2-BTHA could chemically adsorb on pyrite rather than on diaspore. It mainly reacted with pyrite surface Fe to form Fe-S bonds and five-membered hydroxamate-(O, O)-Fe rings. This research provides a potential multi-functional collector for green and efficient utilization of high-sulfur bauxite.