<Original Papers>Some Tests on Roasting of Iron Sulfide

The relation between concentration of sulfur dioxide in flue gas and sulfur content of iron ore was studied under various roasting conditions. Samples were prepared by mixing natural and partially roasted pyrite. The concentration of sulfur dioxide in this bacth test was so measured as to establish a relation applicable to continuous operation in the plant. The results obtained may be summarized as follows : When the sample contain less than 30 pct of sulfur, concentration of sulfur dioxide produced was nearly proportional to sulfur content of the sample. Above this percentage, there seemed to be a tendency to separate elemental sulfur. Amount of sulfur which remained was finally reduced down to about 0.3 pct, this being almost independent of sulfur content of the sample, roasting temperature and air flow rate, under such scale. Besides, the relation between the sulfur content and the amount of unreacted sulfur in the sample was measured under the roasting condition at which the concentration of sulfur dioxide was kept at 8 pct, which was the most effective concentration for recovering it as sulfuric acid