The Kinetic Dissolution of Copper from Chalcopyrite-containing Carbonatite Tailings Samples in Sulphate Media

Abstract

The aim of this study was to determine the rate at which Cu is extracted from the surface of chalcopyrite contained in the tailings from the carbonatitic ore obtained from the carbonate complex in Loolekop, Phalaborwa, South Africa; the rate formation of the passivation phenomena during mineral dissolution was also observed. The objectives of the study, in which the mineral was subjected to sulphate based leaching with ferric sulphate as oxidant were as follows: firstly, to observe the effects of room temperature conditions (25°C) on the extraction rate of Cu in the carbonatite tailings system and secondly to determine the effects of mineralogical composition of species within the host ore on the extraction rate and passivation rate formation. The tailings was subjected to X-ray florescence spectroscopy (XRF) for mineralogical characterization as well as X-ray diffraction spectroscopy (XRD) for bulk elemental composition. Phreeqc simulation software was used for the prediction of mineral species using acidity, alkalinity, chloride ion, pH, ORP and sulphate ion as input parameters. The tailings associated with calcite-magnesium, hematite and quartz was prone to acid attack at room temperature conditions during the initial phases of leaching. During the course of the set leaching time, accumulation of gypsum and jarosite occurred, disrupting the transfer of ions from the mineral surface as 5.55wt% Cu extraction was obtained after the leaching period (12 hour) as opposed to the peak extraction rate after 4 hours of leaching (16.58wt%).