LEACHING OF METAL SULPHIDE CONCENTRATES AT ATMOSPHERIC PRESSURE USING SO2/O2 MIXTURES.

A new process for leaching zinc sulphide concentrates with gaseous mixtures of SO//2 and O//2 in aqueous solution is described. Reaction with Rosebery, Mt. Isa, Broken Hill and Elura zinc concentrates yields zinc and iron sulphates, elemental sulphur and sulphuric acid. Extractions are dependent on SO//2 and O//2 tenors of the gas, particle size, and the acidity and zinc content of the solution, but are independent of the ferric ion level. Extractions reach maxima at about 85 degree C. Generation of acid may be prevented by conducting the reaction in the presence of ferrous iron and at acidities of 40 g/l or greater.