GB731527A - Improvements in or relating to the treatment of sulphides and sulphide minerals - Google Patents

Abstract

Comminuted sulphur-bearing material such as pyrites is subjected to a distillation treatment to remove elemental sulphur and then to a roasting treatment in a separate zone to remove the remaining sulphur as sulphur dioxide, the gases emanating from the distillation step after removal of sulphur, e.g. by p condensation, being applied in controlled amount <PICT:0731527/III/1> to the roasting treatment to regulate its temperature. The roasting treatment is preferably in a fluidized bed, the distilling treatment may be either in a fluidized bed or in a close bed agitated by rabbling. The roasting step may be followed by a third heat treatment, preferably fluidized, e.g. to reduce ferric oxide to magnetite, and the product after quenching may undergo wet magnetic separation. In the apparatus shown in Fig. 1, all three stages are fluidized and the material flows from each bed to the next through conduits 13, 14. The gases from the reduction stage 6 are passed to stage 4 to heat and fluidize the material undergoing distillation. The distillation gases pass through a dust precipitator 27, waste heat boiler 28, and scrubber 29 to a fan 34 which forces them with additional air from 35 into the roasting chamber 5. Sulphur dioxide leaves this at 21. In a modification (not shown), the perforated hearth 9 is omitted from chamber 4 and the distillation is effected in a solid bed agitated by rabbling means, the necessary heat being supplied by conduction through the floor 7 of the chamber. Instead of the supply of heating gases from chamber 6 a purging gas may be admitted at 191. The conduit 13 is replaced by one leading from the edge of the chamber 4 at floor level, the material being directed into it by the rabbling means.