Na₂O-SiO₂系スラグ-炭素飽和溶鉄間の硫黄の分配

抄録

The sulfur partitions between carbon-saturated iron melt and Na₂O-SiO₂ slags with the Na₂O/SiO₂ molar ratio of 3/2, 1/1, 2/3, and 1/3 have been measured at 1 250°C and 1 350°C. The sulfide capacities C'_s[= (wt%S)·(a_O/a_S)] calculated from the sulfur partitions were found to be in the range 10^-2 to 10^-4 and their temperature dependence was not observed. These values were lower than the previous measurement obtained from the gas-slag equilibrium study at the basic slag compositions above Na₂O/SiO₂=0.50.7, but were higher than the previous measurement at the slag composition below this ratio. The sulfur partitions between carbon-saturated iron melt and Na₂O-CaO-SiO₂ melts at the constant silica content were also measured at 1 250°C. The effect of lime on the sulfur distribution was compared with that of Na₂O in the plot of log (S)/[S] versus (Na₂O+mCaO)/SiO₂ ratio, thus resulting m=0.3. The significant amount of iron was observed in the slag phase after equilibration and the ratio of sulfur as FeS against the total sulfur in slag was found to be maximum at the com-position with the Na₂O/SiO₂ molar ratio of 0.9. Desulfurization and dephosphorization of the carbonsaturated iron melts (0.1%P, 0.05%S) by the sodium vapor produced by the reaction of NaCl with CaC₂ were investigated at 1 300°C. Desulfurization was found to occur but no dephosphorization was found.