GB710987A - Improvements in the treatment of materials containing sulphides - Google Patents

Abstract

Materials containing iron sulphides are subjected in the absence or presence of a combustible carbonaceous substance to such a degree of oxidizing conditions that only a partial oxidation of the fixed sulphide content is effected and the temperature controlled below the melting point of the remaining sulphide or subsulphides to promote their reaction with the sulphur dioxide formed to produce sulphur so that together with such sulphur as the sulphides yield directly by thermal dissociation, a high proportion of the sulphur content is evolved in elemental form without any of the other reaction products being fused, slagged, sintered or melted. The process may be performed in a fluidized bed or in a reaction chamber in which the charge moves through the chamber in counterflow to the gas passing over or through it. The conditions are such that about 20-40 per cent. of the total sulphide content is oxidized, depending upon the ore used, and a temperature of up to 980 DEG C. is stated to be satisfactory for a fluidized bed, reduction of sulphur dioxides by the sulphides present being sufficiently rapidly completed at 800-950 DEG C. in a chamber of economic size. The resulting ferroso-ferric oxide may be reduced to metal by means of a carbonaceous reducing substance or oxidized to ferric oxide (e.g. in the case of auriferous pyrites, for cyanidation) in a further separate treatment, e.g. in a fluidized bed. Sulphur may be recovered as solid or liquid by passing the sulphur-containing exit gases through a cyclone and electrostatic precipitator, both operating above the boiling point of sulphur to remove entrained magnetite dust, and then to an electrostatic precipitator operating below the boiling point of sulphur, when sulphur is removed from the gases.ALSO:Magnetite produced from material containing iron sulphide (see Group III) may be fluidized with air or a reducing gas or both and reduced to sponge iron by means of a carbonaceous reducing substance at 850-1000 DEG C.