| Abstract Scope |
Molten salt electrolysis reduces iron-bearing complex oxides, but subsequent smelting separation is governed by phase stability, slag–metal reactions, impurity partitioning, and alumina-crucible interactions. Thermodynamic calculations over 100–1700 °C were used to clarify phase evolution, iron loss, impurity behavior, and alumina consumption. Fe2O3, Fe3O4, FeO, NaFeO2, FeAl2O4, and NaAlSiO4 remain generally stable, whereas FeO can disproportionate below ~500 °C, yielding fine Fe particles that are difficult to coalesce during smelting. NaAlO2 decomposes into Na2O- and Al2O3-rich slag components, and sulfur may enter molten iron as FeS. Although NaFeO2, Na2O, Fe3O4, and Fe2O3 show limited reactivity with Al2O3 individually, coexistence with metallic Fe promotes FeAl2O4 formation and alumina consumption. Therefore, enhanced deoxygenation reduces residual iron oxides, thereby mitigating alumina corrosion and iron loss. Avoiding Al co-reduction prevents FeAl alloy contamination, while Ca-, Si-, and Mn-bearing silicates/ferrites immobilize impurities and high-purity Ar stabilizes metallic iron. |