PROCESS FOR THE PRESSURE OXIDATION ACID LEACHING OF NON-FERROUS METAL AND IRON-CONTAINING SULPHIDIC MATERIAL

A process for the pressure oxidation leaching of non-ferrous metal sulphidic material which comprises providing an autoclave assembly which has a series of successive compartments, the first compartment of which being substantially larger in size than each of the remaining compartments. An oxygen partial pressure is provided in the autoclave assembly in the range of from about 50 to about 2000 kPa. An aqueous slurry of the material is fed into the relatively large first compartment with resultant flow of the material through the successive smaller compartments causing the temperature in the first and successive compartments to be sufficient to produce autogeneous oxidation of the sulphidic material. The oxidized slurry from the last compartment of the series is discharged.