Isao Nakamoto, Hiroshi Saito and Katsumi Mizumaki
In order to investigate the behavior of sulfur in raw materials in the manufacturing process of ferro-manganeses by electric furnaces, the amount of sulphide-S, MnS and CaS in slags were determined respectively. (1) Sulphide-S and sulphate-S; There are two methods for determining sulphide-S in slags, namely direct and indirect methods. By the former sulphide-S is evaluated as 82∼95% of total S, and by the l tter as 83∼99.5%. The fact that higher values (1∼11%) are always obtained by the latter, indicates that slags contain sulphide-S which can't be decomposed by HCl. The sulphate-S content is 1∼17% of total S. (2) MnS and CaS; For MnS, the authors confirmed that Mikhilova's I2-alc. method is applicable for the case where MnO and MnSO4 coexist. For CaS, Al-amalgam method by Ikegami and Kamimori is also applicable for the case where MnS and FeS coexist. By means of the above two methods, Mn slags are analysed for each component. (a) In high carbon ferro-Mn slags (Mn 10∼15%, wt. ratio CaO/SiO2 1.3∼1.5), sulphide-S, combines as MnS and CaS in the ratio of 65∼80% and 20∼30% respectively. (b) In ferro-Si-Mn slags (Mn 3∼6%, CaO/SiO2 1.0∼1.1) sulphide-S combines as MnS and CaS in tne ratio of 83∼95% and 4∼12%.
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