Development of a new hydrometallurgical process to recover oxidised Zn-Pb deposit

摘要

There is a growing interest to recover oxidised zinc lead deposits. Several of them are in remote area or are of too small size to be recovered economically by the usual processes of extractive metallurgy. In order to valorize such kind of deposits we developed at bench scale a new hydrometallurgical process, adapted from the caustic soda process already existing to treat the EAF dusts from steelmaking. In a first leaching step with diluted caustic soda solutions some of the lead but few of the zinc are dissolved. The residue is subsequently leached for zinc and residual lead with a more concentrated caustic soda solution. After solid-liquid separations the two pregnant solutions are treated by selective sulphide precipitation to recover two marketable products: a zinc concentrate and a lead concentrate. Based on this process the building of a 15 t/h plant has been decided.