Study on the Utilization of Pyrrhotite Principally Composed of Iron and Sulfur. I : On the Roasting of Pyrrhotite

Adopting the roasting process for the utilization of pyrrhotite, studies were made of the reciprocal relations among oxidation velocity, oxidation ratio, residual sulfurs in the cinders and production ratio of sulfur trioxide in roasting gases, under the several following conditions : - (1) Flow of air (cc/min/2g) : 100, 150, 300, 500 and 1000. (2) Mesh of ore : 150''?170'', 48''?50'', 20''?24'', 14''?16'', 9''?10'' and 7''?8''. (3) Roasting temperature (℃) : 600, 650, 700, 800 and 900. (4) Roasting time : Below 200 min. The most favourable conditions were confirmed as follows : - 1. The temperature range favourable for roasting is 700°?800℃. 2. In the range described above, sufficiently great oxidation ratios are obtained in the roasting time within one hour up to the mesh of 20''?24'', even in case of 100cc/min/2g. 3. The cinders, roasted in such a condition as described above, contain residual sulfurs which have become under 0.2%, and are sufficiently available for iron-making.