LLC Research Center Hydrometallurgy, Saint Petersburg, Russia
T. Yu. Kositskaya, Senior Researcher, Candidate of Technical Sciences, e-mail: kositskaya-t@gidrometall.ru
A. Yu. Lapin, Chief Researcher, Candidate of Technical Sciences, e-mail: lapin-a@gidrometall.ru

JSC Chelyabinsk Zinc Plant, Chelyabinsk, Russia
M. S. Varganov, Head of the Technical Administration, e-mail: mkv@zinc.ru
O. A. Fatkhutdinova, Chief Technologist of the Technical Administration, e-mail: oaf@zinc.ru

A currently relevant issue is processing of sulphide zinc concentrates of various compositions. In addition to the conventional processing technology for such raw materials, providing for the use of cinder annealing and atmospheric leaching, there is a pure hydrometallurgical method based on autoclave oxidation leaching of the concentrate (temperature is 150 ^oC, oxygen pressure is 0.7 MPa), including a transition of the bulk of sulphide sulphur into elemental sulphur. The article presents the studies on two-stage countercurrent autoclave oxidation leaching of the zinc concentrate from one of deposits of Russia and describes a principal flow chart of its processing. Modern autoclave equipment was used to experimentally test main parameters of each stage of leaching. The authors determined mutual influence of parameters of one process stage on indicators of the other stage, resulting in obtaining parameters of both stages, ensuring a high recovery rate of zinc into a product solution (>98 %) and a high selection rate of zinc and iron during autoclave oxidation leaching. There are options found to produce a zinc product solution with a low content of iron (≤1 g/l) and sulfuric acid (≤5 g/l) to simplify a process flow of cleaning before the electrolytic deposition of zinc. The article presents studies on compositions of solid products, resulting from autoclave leaching. It has been determined that main components of autoclave sediments, besides elemental sulphur, are secondary ferrous phases — crystalline jarosite-type compounds. Obtaining crystalline sediments provides for achieving high sedimentation characteristics of slurry of the 1st leaching stage, simplifying a process flow diagram of its dewatering.

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