Differential flotation of pyrite and Arsenopyrite: effect of pulp aeration and the critical importance of collector concentration

Differences in the oxidation rate and extent of model pyrite and arsenopyrite minerals, augmented by pulp aeration, was investigated using dissolved oxygen demand tests and X-ray photoelectron spectroscopy (XPS) analysis. Flotation studies of single mineral admixture coupled with zeta potential measurements, UV–Vis spectroscopy analysis of collector concentration and ex-situ metal ions in solution after collector addition were ascertained to shed light on reasons for observed window for selective flotation. The highest selectivity was achieved with low collector concentration of 1 × 10-5 M PAX and selectivity index of 5.2 after 6 min flotation with collector concentration playing a critical role in attaining a good selectivity. Fast adsorption of xanthate and simultaneous oxidation to dixanthogen on slightly oxidised pyrite surface starved heavily oxidised arsenopyrite surface of the collector species, at low collector concentration, leading to its depression. The study was extended to the flotation of an auriferous refractory ore where similar observations were made. 62.7% rejection of pyrite was achieved in the staged flotation process Refereed/Peer-reviewed