On the Desulphurization Product by Manganese
Kokichi Sano, Michio Inouye
In a disdussion of the foregoing work, the desulphurization product by manganese was assumed to be probably Mn-sulphide (Tetsu-to-Hagane Vol. 43, 1957, pp. 517-535). However, it seemed doubtful in lower manganese range especially at higher temperature. This paper describes the experimental results of the relations between the composition of desulphuriza-tion product and the Mn-S equilibrium in C-saturated iron melts. The desulphurization product was a sulphide slag which was produced by mixing the liquid FeS and Fe-C-Mn melts at that temperature and brought into equilibrium with C-saturated iron melts.
The results were as follows:
1) The main components of the slag were Mn, Fe and S, and the manganese content in the slag increased with the manganese in the metal and attained constant at above 3% Mn in the metal.
2) From the Norelco X ray analysis, it was assumed that the slags were solutions of FeS or Fe-FeS dissolved into MnS.
3) Considering the manganese in the slag was entirely combined with sulphur, the MnS pct in the slag was found to be constant above 3% Mn in the metal. This value was about 94%. MnS.
4) Regarding the slag as FeS-MnS solution and referring to the FeS-MnS diagram, the activity of MnS might be equal to concentration, which was expressed in terms of mol frac-tion NMnS.
The authors could write the equilibrium constant K=NMnS/aS·aMn=0·428 at 1500°C From this value the apparent equilibrium constant K″=[Mn%]·[S%] in lower manganese range was discussed.