Study on the Utilization of Pyrrhotite Principally Composed of Iron and Sulfur. III : On Sulfur Making by the Catalytic Reduction of Roasting Gases with Blast Furnace Gases

1. In the first place, pure sulfur dioxide was catalytically reduced with pure carbon monoxide, using three kinds of catalyser, and the following conditions were studied with a view to obtaining the greatest yields of sulfurs : - (1) Kind of catalyser. (2) Temperature of catalyser. (3) Decrease of catalyser-efficiency, due to continuous use. (4) the relation between weight of catalyser and flow of gas. 2. From a practical standpoint the use of blast furnace gases, instead of pure carbon monoxide, yielded comparatively better results, preventing the decrease of catalyser-efficiency, because of dilution of gas with nitrogen. 3. Finally, using the roasting gases, from which oxygen was removed, in place of pure sulfur dioxide, still better results were otained

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\u27\u27?170\u27\u27, 48\u27\u27?50\u27\u27, 20\u27\u27?24\u27\u27, 14\u27\u27?16\u27\u27, 9\u27\u27?10\u27\u27 and 7\u27\u27?8\u27\u27. (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\u27\u27?24\u27\u27, 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

Study on the Utilization of Pyrrhotite Principally Composed of Iron and Sulfur. II : On Making Sulfuric Acid from the Roasting Gases of Pyrrhotite

Considering the results obtained in the preceding paper, the pyrrhotite, mesh of which is 28\u27\u27～32\u27\u27, was roasted at 700℃ using a baby rotary furnace, and from the roasting gases sulfuric acid was made by the contact process. Finally, the following results may be stated : - 1. As for our contact process for making sulfuric acid, the most favourable conditions are as follows : - (1) The sulfur dioxide concentration is 7～7.5%. (2) The temperature of catalyser is about 440℃. 2. The pyrrhotite cinders, which are obtained in roasting 75～120g. of ores (28\u27\u27～32\u27\u27) for 30～48 hours at 700℃ in a baby rotary furnace, contain residual sulfurs, which amount to 0.2～0.4%, and are sufficiently available for iron making

Study on the Utilization of Pyrrhotite Principally Composed of Iron and Sulfur. IV : On the Direct Reduction of Roasting Gases with Cokes

1. Adopting the method to make the ratio of the contents of sulfur dioxide to those of oxygen in the course of roasting pyrrhotite equal to about same weight, the resulting roasting gases are introduced into the direct reducing furnace with coke, and the relations between the obtained yield of sulfurs and the reaction temperatures were found. 2. Even if the yield of sulfurs attained to only 70% and thereabout in the case of adopting 850℃ as the reaction temperature, the ratio of carbon monoxide to sulfur dioxide in the produced gases became 2 : 1, and it was found that almost the entire amount of residual sulfur dioxide in the above reaction could be reduced to the simple sulfurs by application to those resulting mixed gases of the catalytical reducing method, reported in the previous paper (part 3). 3. Further, adopting 900℃ as the direct reducing temperature described above, the yield of sulfurs in this reaction attained to 90%, but it was found that in this case, the ratio of sulfur dioxide to carbon monoxide became more than 4 : 1, and even in the case of applying the catalytic reduction, reported in part 3 of this paper, to the resulting mixed gases, carbon monoxide was tolerably lost