COMMERCIAL OPERATIONS OF THE SHERRITT ZINC PRESSURE LEACH PROCESS

The use of autoclaves for the recovery of metals, using aqueous sulpha te systems, has been a focus of Sherritt Inc. for more than 40 years. Following the pioneering commercialization of a pressure hydrometallur gy process in 1954 for nickel production, Sherritt Technologies have c ontinued to develop and assist in the commercial implementation of aut oclave processes for other metals, notably gold and zinc. The direct p ressure oxidation of zinc sulphide concentrates to produce zinc sulpha te solutions which are suitable for conventional recovery of zinc by e lectrowinning, while oxidizing the sulphide sulphur only as far as its elemental form, has been promoted by Sherritt for more than 30 years. Its commercial realization in 1981 by Cominco Ltd., at Trail, B.C., h as been followed by Kidd Creek Division of Falconbridge Limited at Tim mins, Ontario, in 1983 and Ruhr-Zink at Datteln, Germany, in 1991. In 1993, the elimination of a zinc roaster operation was achieved by Huds on Bay Mining and Smelting, through the installation of three autoclav es. This paper was prepared jointly by the operators of the pressure l each circuits at four zinc plants and focuses on the operating results and improvements achieved over the years, as well as the principal ch emistry of the process.