Copper extraction from reverberatory and flash furnace slags by chlorine leaching

The effects of the stirring speed, temperature, initial chlorine and chloride concentrations, particle size, addition order of the reactants and slags on the copper and iron dissolution from reverberatory and flash furnace slags were investigated. Extractions in the range of 75 and 80% Cu and about 5% Fe were obtained at room temperature. The most significant parameters were the particle size and the initial chlorine concentration. A mineralogical characterization of the reverberatory and flash smelting slags, using X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM) coupled to an X-ray energy dispersive spectrometer(EDS) and microanalysis (EPMA), was made. This characterization indicated that most of the copper is in the form of metallic copper, chalcocite, bornite and other complex sulphides of very small size, mainly 5-10 mu m. Iron is present principally as the matrix of a vitreous phase, fayalite and magnetite. An average only 0.2-0.4% of the copper was found in the silicate phases. (C) 1998 Elsevier Science B.V. All rights reserved.