Sulphation roasting studies on synthetic copper–iron sulphides with steam and oxygen

Abstract

The direct sulphation of individual and mixed sulphides of copper and iron has been studied using a steam–oxygen mixture as the oxidant. The investigation showed that copper sulphide formed copper sulphate with this gaseous mixture at 773 K, whereas iron sulphide converted mostly to hematite at this temperature. It was also observed that the mixture of copper–iron sulphides yielded a higher amount of copper sulphate (92.7%) than that obtained (40.0%) from copper sulphide alone in the presence of 10 wt.% ferric oxide. This was mainly attributed to an improved sulphatising environment during the roasting of mixed sulphides. The kinetics study of the CuS–FeS system with a steam–oxygen mixture showed that the copper sulphate formation followed the topochemical model. An activation energy value for this conversion was found to be 30.36 kJ/mol in the temperature range 673 to 773 K. The sulphides and different calcined products obtained were characterised by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and the metallographic studies to examine the path of reaction.