Recovery of zinc from sulphidic material

摘要

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 in excess aqueous sulphuric acid solution to produce an undissolved residue containing a major proportion of lead and/or silver and a leach solution (A) containing a major proportion of the zinc and iron. The leach solution (A) 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. Zinc is recovered from a leach solution, and the zinc ferrite containing residue is leached in a strong aqueous sulphuric acid solution comprising at least a portion of the leach solution (A) 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.