Exploring the Potential of B₂O₃ and SiO₂ to Dissolve MgAl₂O₄ from Experiment and AIMD Simulation

Given its energy-saving benefits and the shortened steelmaking process, the method of direct chromium alloying by directly introducing chromite ore into carbon-containing iron melt has captured the interest of numerous researchers. MgAl₂O₄ with high melting point and high chemical stability could form during chromite ore reduction by carbon dissolving in the iron melt, which slows the reduction process. Thermodynamic analysis suggests that SiO₂ and B₂O₃ are two potential oxides to dissolve the MgAl₂O₄ spinel. The reduction extent of chromite ore without flux addition is only 17.5% after 90 min. The reduction extent of chromite ore with B₂O₃ and SiO₂ addition after 30 min reaches 73.83% and 28.27%, respectively. The ab initio molecular dynamics (AIMD) simulation is performed to clarify the dissolution mechanism of MgAl₂O₄ in B₂O₃ and SiO₂. Results indicate that the break of the Mg-O bond in MgAl₂O₄ initiates the destruction of the MgAl₂O₄ structure. The crystal orbital Hamilton population (COHP) analysis shows that the O in [BO₃]³⁻ has a stronger attraction to Mg than that in [SiO₄]⁴⁻, which results in a stronger ability of B₂O₃ to dissolve MgAl₂O₄ compared to SiO₂.