Abstract: The invention provides a hydrometallurgical process for treating metal-containing sulfide ores and concentrates, comprising reacting said metal-containing sulfide with concentrated sulfuric acid at a temperature of between about 300° C. and 400° C. in the presence of oxygen to produce a solid metal sulfate product and a gaseous product which is primarily SO3, wherein said metal is selected from the group consisting of iron, copper, zinc, nickel, cobalt and manganese. Said metal sulfate product is then leached with dilute sulfuric acid to form a metal-containing solution, from which the metal values are separated by precipitation at raised H2SO4 concentrations obtained by saturating the solution with the gaseous SO3 from the sulfatization reaction step.

Abstract: The invention provides a hydrometallurgical process for extracting noble metals from raw materials containing the same, comprising(a) leaching the raw materials with a mineral acid to leave a residue containing the noble metals,(b) treating said residue with a substantially non-aqueous liquid comprising bromine and an apolar organic solvent in which bromine dissolves, to form a complex of the formulaR[MeBr.sub.x ]whereinx=4-6Me=Au, Ag, Pt, PdOs, Ru, Rh, Irand R is an organic moiety of the solvent, and(c) subjecting the complex-containing substantially non-aqueous liquid to electrolysis whereby noble metal is deposited on the cathode and removable therefrom and bromine liquid is formed at the anode and immediately dissolves in the organic solvent.