HYDROMETALLURGICAL PROCESS FOR THE TREATMENT OF A RAW MATERIAL WHICH CONTAINS OXIDE AND FERRITE OF ZINC, COPPER AND CODMIUM

A hydrometallurgical process for the treatment of a raw material which contains oxides and ferrites of zinc, copper and cadmium is disclosed, wherein the raw material is neutral leached by means of a sulfuric-acid-bearing solution to leach the oxides without substantial dissolving of the ferrites, a ferritebearing residue is separated, and a sulfuric-acid-bearing or ferrisulfate-bearing solution is mixed with the residue in order to leach the ferrite and to precipitate the iron in the form of jarosite in the presence of alkali or ammonium ions under atmospheric conditions at 80-105.degree.C, and the solid phase is separated from the solution. The sulfuric-acid-bearing or ferrisulfate-bearing solution is added to the ferrite-bearing residue in such an amount that approximately 50-60 % of the ferrite dissolves and its iron is precipitated as jarosite, and the slurry of the solid phase is treated at such elevated pressure and temperature that the zinc of the solid phase is converted to zinc sulfate and the iron to hematite in accordance with the following reaction: (5) 3ZnFe2O4(s) + 2A¢Fe3(SO4)2(OH)6!(s) ? 3ZnSO4(aq) + A2SO4(aq) + 6Fe2O3(s) + 6H2O(aq) (A=K, Na, NH4)