Flotation separation of pyrite from arsenopyrite in the presence of oxidants

ABSTRACT

Four oxidants, NaClO, KMnO₄, K₂Cr₂O₇, and H₂O₂, were used to promote the flotation separation of pyrite (FeS₂) from arsenopyrite (FeAsS). Ore flotation results indicate that H₂O₂ has the best selectivity for the As-S separation. When H₂O₂ is used, the As content in pyrite concentrate decreases from 2.27% without addition of H₂O₂ to 1.11% with H₂O₂ dosage of 900 g/t, and the pyrite recovery is still high (86.58%). NaClO, KMnO₄, and K₂Cr₂O₇ have poor selectivity for the As-S separation. Cyclic voltammetry measurements by using mineral microelectrodes indicate that H₂O₂ shows selective oxidation effect on arsenopyrite while other three oxidants have no selective oxidation effects on arsenopyrite and pyrite. In the presence of dixanthogen coating on the mineral surface, all the four kinds of oxidants can oxidize dixanthogen to a certain degree. Moreover, the collector coatings on arsenopyrite surface are oxidized more easily than on pyrite.