Adsorption mechanism of 3-mercaptopropionic acid as a chalcopyrite depressant in chalcopyrite and galena separation flotation

3-mercaptopropionic acid (MPA) is an ideal depressant in chalcopyrite-galena separation due to the advantages of high efficiency, environmental friendliness, and low dosage. However, its inhibition mechanism for chalcopyrite was unclear. In this study, the adsorption mechanism of MPA on the chalcopyrite surface was investigated in detail to understand its excellent inhibition effect on the flotability of chalcopyrite. The flotation and surface variation of chalcopyrite and galena were examined by micro-flotation experiments, Fourier transform infrared spectroscopy (FT-IR) analysis, X-ray photoelectron spectroscopy (XPS) studies, and atonic force microscopy (AFM) observation. The micro-flotation experiments results indicated that MPA exhibited a superior selective inhibition ability than that of thioglycolic acid (TGA) even under a relatively lower concentration. The surface analysis revealed a significant decrease of SBX adsorption on the chalcopyrite surface after pre-treatment with MPA. While the pre-treated galena surface still kept strong interaction with SBX. Moreover, the AFM observation clearly demonstrated that the adsorbed MPA molecules formed a network structure on the chalcopyrite surface due to the hydrogen-bond interaction, which could dramatically enhance the adsorption stability of MPA on the chalcopyrite surface, depressing the subsequent SBX chemosorption. These results shed light on the characteristic inhibition mechanism of MPA, which promotes its practical application on chalcopyrite and galena separation flotation.