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Abstract

A process for recovering zinc from zinc containing sulphidic material which also contains iron together with lead and/or silver includes leaching the material under oxidizing conditions at a temperature in the range of from about 130.degree. to about 170.degree. C. in aqueous sulphuric acid solution with a stoichiometric excess of sulphuric acid relative to the zinc content of the material of from about 40 to about 100% to produce an undissolved residue containing a major proportion of lead and/or silver and a leach solution containing a major proportion of the zinc and iron. The residue is separated from the leach solution and treated to recover lead and/or silver values. The leach solution is treated to recover zinc by feeding the solution to another process in which zinc-containing material is treated to recover zinc and which includes an iron-precipitation step. The other process includes roasting zinc and iron containing sulphidic material to produce a zinc oxide and zinc ferrite containing material, which is then leached in a weak aqueous sulphuric acid solution to dissolve zinc oxide and produce a leach solution containing dissolved zinc and a zinc ferrite containing residue. The residue is separated from the leach solution. Zinc is recovered from the leach solution, and the zinc ferrite containing residue is leached in a strong aqueous sulphuric acid solution to dissolve zinc ferrite and produce a leach solution containing dissolved zinc and iron and a residue, with the strong aqueous sulphuric acid solution comprising at least a portion of the leach solution containing a major proportion of zinc and iron. The leach solution containing dissolved zinc and iron is separated from the residue. Ferric iron in the leach solution is reduced to ferrous iron, and the ferrous iron is neutralized and hydrolyzed under oxidizing conditions to precipitate an iron compound, and the iron compound is separated from the remaining solution.

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