procedure for the extraction of metallverden from jerninnehallande materials

摘要

The invention relates to a method for recovering non-ferrous metal values from iron bearing materials of the type iron sulphides or decomposition and roasting products thereof, by subjecting the material to a sulphating roasting process and leaching the sulphated material. The sulphated material is leached with a chloride-containing aqueous solution while supplying an oxidation agent in an amount so chosen that any arsenic present is bound as iron arsenate, that any alkali metals present are bound as jarosites and so that a redox potential suitable for binding a readily dissolved metal chloride complex is obtained. The leached material is separated from the solution and washed with water, whereafter the material is removed from the process in the form of an iron oxide product. The separated solution is freed from valuable metals by cementation, whereafter the cementated metal content is separated and recovered. Sulphate ions in the solution are precipitated as gypsum, which is separated from the solution and any residual valuable metal ions thereon are precipitated out in a suitable manner and separated from the solution. At least a part of the solution is recycled as leaching liquid for the sulphated material, subsequent to the sulphating process.