Author Description

Various methods for the treatment of a low-grade nickel-copper-cobalt concentrate from the Uitkomst ore-body are described. It is shown that, owing to the nature of the mineralogical composition of the concentrate, direct leaching does not dissolve all the base metals. However, the mineralogical composition can be changed by a variety of heat-treatment processes, and the concentrate then becomes amenable to leaching. The favoured process route is electric-furnace smelting to produce a low-grade matte in which more than 90 per cent of the sulphur in the concentrate is retained as sulphide sulphur. This is achieved by use of ferric oxide and coal char as fluxes. Leaching of low-grade matte is shown to result in good extraction of the base metals into solution and oxidation of the sulphide to sulphur. Attempts to recover the platinum-group metals as an upgraded residue are also described.