Use of PASP and ZnSO4 mixture as depressant in the flotation separation of chalcopyrite from Cu-activated marmatite

In this study, the synergistic depressive effect of polyaspartic acid (PASP) and zinc sulfate (ZnSO₄) in the flotation separation of chalcopyrite from Cu-activated marmatite was investigated by micro-flotation experiments and ore sample flotation tests, and the possible depressive mechanism was proposed from contact angle measurements, fourier transform infrared (FT-IR) analysis, inductively coupled plasma (ICP) measurements and X-ray photoelectron spectroscopy (XPS) analysis. Microflotation tests indicated that the mixed depressant PASP/ZnSO₄ (PZ) exerted strong depressive effect on Cu-activated marmatite in the pH range of 9~12, but it had little effect on chalcopyrite flotation. The ore sample flotation experiments indicated the PZ system decreased the grade of Zn in Cu concentrate by 4.18%, and the depressant consumption was reduced by more than a half. The results from contact angle measurement demonstrated that the hydrophobicity of Cu activated-marmatite surface was higher than that of chalcopyrite surface in presence of PZ. FT-IR analysis demonstrated the more intensive chemisorption of PZ on Cu-activated marmatite surface. ICP measurements showed that PASP had an excellent complexing ability with Cu²⁺ and Zn²⁺, which not only reduced the activation of Cu species, but also generated Zn-PASP complex on marmatite surface. XPS analysis indicated a stronger interaction between PZ and Cu-activated marmatite surface, and the depressant PZ may mainly react with Cu-activated marmatite surface through the copper atoms.