Determination of Solubility of Chromium Oxide in the CaO–SiO₂–Cr₂O₃ Slag System at 1873 K under Moderately Reducing Conditions

抄録

For a better thermodynamic understanding of the optimization of molten slag in the stainless-steel refining process, the solubility of chromium oxide in the CaO–SiO₂–Cr₂O₃ slag system was investigated. A chemical equilibrium technique was employed in which molten slag and solid Cr₂O₃ pellets were equilibrated under a regulated oxygen partial pressure (P_O2) lower than 10⁻¹¹ atm at 1873 K. The mass ratio of CaO to SiO₂ (X_CaO / X_SiO2), as an index of slag basicity, was varied from 0.5 to 1.5. A CO–CO₂–Ar gas mixture was used, and the oxygen partial pressure was precisely controlled by evaluating possible contamination by oxygen that was inevitably introduced into the gas mixture system. A zirconia oxygen sensor was used to directly measure the oxygen partial pressure for this evaluation. The solubility of chromium oxide increased with decreasing slag basicity and oxygen partial pressure. Accordingly, slag design is a huge prospect toward achieving desirable refining conditions.