STUDIES ON AREAL AND NH4CL ROASTINGS OF CU-NI SULFIDE CONCENTRATES

Studies on the kinetics of preferential areal sulphation of copper sul phide present in the complex sulphides concentrate of Cu,Ni and Fe, ob tained from the Jinchuan mine, Gansu, China, were carried out in the t emperature range of 375-degrees-C to 475-degrees-C The kinetics of the areal sulphation was found to follow the mechanism of nucleation and growth of the product, fitting to the equation, -ln (1-alpha) = (kt)m. The activation energy of the process was found to be 25 kcal. mole-1. By two stage roasting, first at 500-degrees-C for 4 hours and then at 600-degrees-C for 2 hours, it was possible to extract about 93% Cu, a long with 16% Ni and 5% Fe as water soluble sulphates. The residue obt ained after filtration was treated with NH4Cl (87.5% by wt. of the cha rge) at 400-degrees-C for ten hours, resulting in the extraction of an other 72% Ni, rest of Cu with about 4% Fe.