Innovative discovery on the impact of hydration on the alternative flotation of smithsonite and calcite under benzohydroxamic acid system

Currently, it is still lacking of deep understanding of the alternative of benzohydroxamic acid (BHA) on smithsonite and calcite flotation. We hypothesize that the presence of hydration films plays a significant role. Therefore, this paper aims to uncover the impact of hydration on the alternative flotation of smithsonite and calcite with BHA, utilizing flotation experiments, DFT calculations, Zeta potential tests, FTIR measurements, and XPS analyses. The results of the flotation experiments confirmed the effective separation of smithsonite from calcite with BHA. DFT calculations innovatively discovered that Zn on the surface of smithsonite can interact with BHA− but the Ca on the surface of calcite was easier to interact with the H2O instead of BHA−, thus BHA was incapable of repelling the hydrated layer from the surface of calcite to interact with the calcium ions. Zeta potential tests, FTIR measurements, and XPS analyses further provided experimental support that BHA was selectively chemically adsorbed onto the surface of smithsonite via forming Zn-BHA complex, whereas no such interaction occurred with the surface of calcite by generating Ca-BHA complex, which validated the DFT calculation results. This study provides valuable insights into the role of hydration in the beneficiation of smithsonite and calcite.