Effect of FeO and CaO on the Sulfide Capacity of the Ferronickel Smelting Slag

The effect of FeO and CaO on the sulfide capacity in MgO-SiO 2 -FeO based slags equilibrating with Fe-Ni alloys at 1773 K and 1873 K (1500 °C and 1600 °C) was investigated. The sulfide capacity in the MgO-SiO 2 -FeO and MgO-SiO 2 -CaO-FeO slags increased with higher FeO content and higher temperatures due to an increase in the activity of O 2− and a decrease in the activity coefficient of sulfide ion in slag. The sulfide capacity of the MgO-SiO 2 -CaO-FeO slag also increased with an increase in the CaO content due largely to the increase in the activity of O 2− . Furthermore, CaO and FeO seem to be more effective than MgO in increasing the sulfide capacity in the MgO-SiO 2 -CaO-FeO slag system. In addition, the comparison of the experimental results with the theoretical estimate using the modified empirical optical basicity showed relatively good linear agreement.