Selective depression mechanism of polyaspartic acid and calcium oxide on arsenopyrite after copper ions activation and its effect on flotation separation performance

The arsenopyrite activated by copper ions have similar flotation properties to chalcopyrite. Polyaspartic acid (PASP) and calcium oxide (CaO) using as combination depressants for the selective separation of copper-activated arsenopyrite and chalcopyrite were carried out by micro-flotation experiments, contact angle measurements, surface adsorption capacity tests, zeta potential measurements, X-ray photoelectron spectroscopy (XPS) analyses, inductively coupled plasma-optical emission spectrometer (ICP-OES) tests and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses, and its depression mechanism was investigated. The results of flotation experiments showed that the recovery of arsenopyrite after addition of the depressants reached only 7.80 %, while the recovery of chalcopyrite reached 94.02 %. The results of contact angles, adsorption capacity tests and zeta potential measurements showed that the PASP-CaO can selectively enhance the hydrophilicity of arsenopyrite surface, but has little effect on the chalcopyrite. XPS analyses and ICP-OES tests further verified that the depressants first eliminated the activation of copper ions and then selectively adsorbed on the surface of arsenopyrite. ToF-SIMS analyses showed that the PASP-CaO would achieve selective depression of arsenopyrite in the form of PASP, PASP-Ca complexes and Ca(OH)+, respectively. Finally, the mechanism diagram of PASP-CaO selectively depressing arsenopyrite was derived. These results will provide an excellent theoretical reference for the flotation separation of copper arsenic sulfide ore. [Display omitted] •An innovative depressant of PASP-CaO was explored for depressing the FeAsS.•Recovery difference between FeAsS and CuFeS2 reached 85.48 % after adding PASP-CaO.•PASP preferentially complexed with Cu2+ to eliminate the surface activation.•Ca(OH)+, PASP and PASP-Ca complexes adsorbing on the FeAsS surface were found.