Selective adsorption of hydrolyzed polymaleic anhydride as an eco-friendly depressant for the efficient separation of pyrite from serpentine

In this study, we aimed to address the problem of fine-grained serpentine forming “slime coating” on the surface of pyrite, which deteriorates the flotation of pyrite, by systematically investigating the effects of HPMA on the separation of pyrite and serpentine, as well as the underlying mechanism. The flotation results indicated that the recovery of pyrite deteriorated by serpentine was significantly increased and reached 90 % by adding 30 mg/L of HPMA at pH 9.00. The total organic carbon (TOC) test and zeta potential test results revealed that the adsorption of HPMA on serpentine was much stronger than that on pyrite. The adsorption behavior was confirmed by X-ray photoelectron spectroscopy (XPS) analyses, which demonstrated that HPMA could chelate with positively charged Mg ions on the surface of serpentine, resulting in a significant change in the surface charge of serpentine to a negative state. The positive effect of HPMA on pyrite flotation was visualized by a scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) analyzer and characterized by the major elemental content. As a result of the addition of HPMA, the surface charge of serpentine was changed from positive to negative, which resulted in the disruption of co-cohesion between serpentine and pyrite. This result enhanced the natural floatability of pyrite and the adsorption of collector potassium amyl xanthate (PAX) on pyrite, thus achieving the selective flotation between pyrite and serpentine.