Effect of the difference in adsorption of DL-2-amino-3-mercaptopropionic acid on the surfaces of jamesonite and pyrite on flotation separation

Abstract

Conventional flotations for separating jamesonite and pyrite employ cyanide as a pyrite flotation inhibitor, leading to significant environmental concerns. In this study, density functional theory calculations were utilized to investigate the differences in the adsorption of DL-2-amino-3-mercaptopropionic acid (DL) on jamesonite and pyrite surfaces. The potential of DL as a pyrite flotation inhibitor was assessed based on atomic coordination, spatial alignment, and orbital compatibility, which was subsequently corroborated by experimental data. Findings indicated that the Fe sites on the jamesonite surface were constrained by steric effects, rendering them challenging for inhibitor adsorption. Effective adsorption of flotation inhibitors on mineral surfaces necessitates meeting both spatial and orbital requirements. Although the Pb and Sb sites on the surface fulfilled the spatial criteria for inhibitor adsorption, strong adsorption was hindered by orbital mismatch. In contrast, pyrite satisfied the spatial criteria for inhibitor adsorption, where the t and e orbitals, derived from the Fe²⁺ d orbital, formed σ-bonding and π-backbonding with DL. This was validated by pure mineral flotation and time-of-flight secondary-ion mass spectrometry. Results of this study considerably demonstrate the potential of DL, fulfilling both spatial and orbital requirements, as a promising pyrite flotation inhibitor for the flotation separation of jamesonite and pyrite.