Recovery of sulphur

摘要

Sulphur is obtained by subjecting iron sulphide to high temperature oxidation to produce iron oxide and gases containing sulphur dioxide which are then passed through a porous charge of pyrites and solid carbonaceous material to effect removal of the labile sulphur from the pyrites and reduction of the sulphur dioxide to sulphur, preferably the iron sulphide remaining then being oxidized as above. The iron sulphide may be oxidized in suspension or in the form of a molten bath, and the pyrites and carbonaceous material may be in the form of a solid bed or be treated in suspension. In the arrangement shown, a mixture of finely divided pyrites and carbonaceous material is fed into distillation and reduction chamber 12 from a hopper 51 and is there treated in suspension with the hot gases from the oxidizing chambers introduced through tuyeres 55. The gases containing sulphur pass through a dust collector 15, water-cooled condenser 16, preferably maintained at 115--150 DEG C. and finally through an electrical precipitator 19. The solid product, mainly iron monosulphide, is passed via conveyer 20 to the molten bath oxidizing chambers 10 and 11. Oxidation is effected by air blown in through tuyeres 30 and 31, such air preferably being preheated by the hot reaction gases in heat-exchangers 13 and 14. The iron sulphide may be introduced into the chambers 10 and 11 over an extended period until they are full, and when the oxygen content of the gases leaving a chamber increases, such gases are passed in series through another chamber containing a charge of higher sulphur content, or preferably the operation of the chambers is staggered so that they are charged and tapped at different times, thus ensuring continuous operation. The oxidation is carried out to produce gases at over 1000 DEG C. and containing substantially no free oxygen. When suspension roasting is used, the monosulphide is preferably ground to minus 40 mesh before oxidation.