Eilectrochemical Investigations into the Flotation Chemistry of Pentlandite and Pyrrhotite: Process Water and Xanthate Interactions

Abstract

Electrochemical studies were conducted to determine if ions present in the Copper Cliff process water at INCa's Sudbury complex were interactive on pentlandite and pyrrhotite surfaces. It was found that Ca2+, S2O32− and SO42− were significantly surface active at the normal process pH. From comparisons of other voltammetric traces obtained for xanthate interactions it was concluded that these ions would influence the extent of adsorption of X− by the sulphide minerals as well as control the onset of hydrophobicity. Simple hydrophobicity tests confirmed that S2O32− and Ca2+ competed with xanthate for adsorption on the surface of pentlandite whereas only Ca2+ increased the xanthate dosage required to render pyrrhotite hydrophobic. Mechanisms for pentlandite and pyrrhotite flotability arising from xanthate reactions were put forward. Xanthate chemisorption took place on the nickel sites in the case of pentlandite, which was oxidized at the surface to form dixanthogen which enhanced hydrophobicity. No xanthate chemisorption took place on pyrrhotite, the surface being rendered hydrophobic by dixanthogen which was formed as part of a mixed potential reaction involving with the normal pyrrhotite oxidation process.