The enhanced sulfidation mechanism of surface activation in hemimorphite through ammonium complexation: An experimental and density functional theory study.

[Display omitted] • The addition of ammonia solution increased the flotation recovery rate of hemimorphite. • After adding ammonia, more ZnS was formed on the hemimorphite surface. • The presence of H 2 O hinders the adsorption of HS− on the hemimorphite surface. • The adsorption energy of HS− on the hemimorphite surface with ammonia solution is lower than that without ammonia solution. This study investigated the impact of ammonia (NH 3) solution on the flotation behavior of hemimorphite sulfidation, employing a comprehensive analysis that encompasses micro-flotation experiments, X-ray photoelectron spectroscopy (XPS) analysis, contact angle testing, atomic force microscopy (AFM) imaging, and density functional theory (DFT) calculations. The introduction of ammonia water (NH 3 ·H 2 O) resulted in a significant 22.64 % increase in hemimorphite recovery rate, as demonstrated in flotation tests. In this study, both XPS and AFM analyses provided compelling evidence supporting the assertion that NH 3 ·H 2 O facilitated the sulfidation of the mineral surface, resulting in an increased formation of sulfide products. Contact angle testing indicated that surface modification with NH 3 ·H 2 O enhanced the hydrophobic properties of the hemimorphite. DFT calculations offered valuable insights into the effect of NH 3 on the hydration layer, indicating that NH 3 substituted H 2 O molecules and increased the distance between Zinc (Zn) and O5 (H 2 O) to 5.6 Å. Furthermore, the adsorption energy of HS− on the hemimorphite (1 1 0) surface significantly increased with NH 3 enhancement (−18.05 eV) as opposed to without NH 3 enhancement (−12.79 eV). These results indicated that the adsorption configuration of NH 3 in conjunction with HS− was more stable than that of HS− alone on the hemimorphite (1 1 0) surface. Thus, the collective results provided valuable insights into the enhanced sulfidation mechanism activated by ammonium complexation on the hemimorphite surface. [ABSTRACT FROM AUTHOR]