Flotation separation of chalcopyrite from pyrite using mineral fulvic acid as selective depressant under weakly alkaline conditions

Mineral fulvic acid (MFA) was used as an eco-friendly pyrite depressant to recover chalcopyrite by flotation with the use of the butyl xanthate as a collector. Flotation experiments showed that MFA produced a stronger inhibition effect on pyrite than on chalcopyrite. The separation of chalcopyrite from pyrite was realized by introducing 150 mg/L MFA at a pulp pH of approximately 8.0. The copper grade, copper recovery, and separation efficiency were 28.03%, 84.79%, and 71.66%, respectively. Surface adsorption tests, zeta potential determinations, and localized electrochemical impedance spectroscopy tests showed that more MFA adsorbed on pyrite than on chalcopyrite, which weakened the subsequent interactions between pyrite and the collector. Atomic force microscope imaging further confirmed the adsorption of MFA on pyrite, and X-ray photoelectron spectroscopy results indicated that hydrophilic Fe-based species on the pyrite surfaces increased after exposure of pyrite to MFA, thereby decreasing the floatability of pyrite.