Abstract: A method is disclosed for oxidation of finely-divided sulphide ores or mattes containing iron, with one or more of the elements nickel, copper, cobalt, zinc and lead as constituents, in the presence of iron chloride in an oxygen-containing atmosphere at a temperature of 220.degree.-400.degree. C, to convert the mixture of iron chlorides and sulphides to water-insoluble iron oxide, the nickel, copper, cobalt and zinc being converted to water-soluble chlorides and sulphates, and the lead to a sulphate which may be leached away from the residual iron oxide by special solvents for lead sulphate. The initial iron chloride is preferably obtained by adding aqueous hydrochloric acid to the concentrate, if iron sulphide is present in a susceptible form, to drive off a portion of the sulphide sulphur as hydrogen sulphide gas, and to convert the corresponding iron sulphide to iron chloride. Temperatures may rise as high as 450.degree. C during the roasting phase if special conditions are observed while cooling.

Abstract: An improved method for agglomerative fluid bed roasting of metal sulphide particles. The sulphide particles are fed as an aqueous slurry through the freeboard of the roaster onto the surface of a bed of roasted calcine agglomerate particles fluidized by a free oxygen-bearing gas. Slurry water is evaporated in the bed and the sulphides are roasted therein. The feed rates of sulphide, water and free oxygen-containing gas are controlled to ensure temperatures in the roaster such that fusion occurs during roasting and agglomerated calcine particles are formed with regular, rounded surfaces. Calcine particles small enough to become entrained in the roaster off-gases are readily disengaged therefrom in cyclones to provide substantially dust-free SO.sub.2 -bearing gas. A preferred practice of the method is feeding substantially the stoichiometric amount of free oxygen to convert the sulphide to SO.sub.