A novel hydrometallurgical treatment for the recovery of copper, zinc, lead and silver from bulk concentrates

Abstract

Nowadays sulphide ores exploitation is undergoing some troubles, which are hindering the treatment through traditional routes. Bulk flotation followed by a novel hydrometallurgical process can dodge these difficulties. In this work, an integral hydrometallurgical process consists of two ferric leaching steps, followed by a hot brine leaching stage, is proposed to recover target metals from a bulk sulphide concentrate (2.9% Cu, 7.4% Zn, 2.5% Pb, 67 ppm Ag and 37.2% Fe). In the first ferric leaching step, sphalerite, galena and copper secondary sulphides are dissolved and, in the second leaching step, a silver salt is added in order to catalyse chalcopyrite oxidation. If silver salt is added at the beginning of the process, sphalerite passivation is observed, and therefore zinc recovery is not possible. However, when catalytic leaching is performed after a previous ferric leaching, copper and zinc recoveries higher than 95% are achieved. The leached concentrate (0.3% Cu, 0.8% Zn, 3.3% Pb, 1438 ppm Ag, 38.0% Fe and 6.6% S0), is treated by a hot brine leaching. When hot brine leaching is performed at high pulp density, elemental sulphur removal is necessary to recover all silver added as a catalyst. Extractions higher than 95% for Zn, Cu and Pb are achieved as well as the total recovery of catalyst. The proposed process is silver surplus; therefore, this agent can be recirculated.