<Original Papers>Recovery of Elemental Sulphur from Iron Sulphide Ores by Roasting in SO_2 Atmosphere

For recovery of elemental sulphur and iron oxide suitable for pig iron production, the reaction [numerical formula] might be considered as possible. Powdered pyrite assayed at 95% FeS_2 was roasted in the atmosphere of SO_2+N_2 in a fluidized roasting furnace, of which the reaction tube made of 18% Cr steel was 10 cm in diameter and 1 m in hight. In fluidization, the reaction of FeS with SO_2 was controlled by chemical reaction itself on the surface of FeS. Arrhenius plot gave a staight line, indicating that the energy of activation was about 22 kcal/mol. The composition of gas mixture which circulated through cyclones, a sulphur condenser, a bag filter and a preheater had no effect on the reaction rate in the range higher than 50% SO_2. The reaction was slow at the temperature lower than 750℃, but when the temperature was raised to 900℃ or higher, sintering occurred. When the ore was fed constantly and the experiment was continued for 6 hours, the residual sulphur in the roasted ore reached 4～8%