LAUSR

Abstract The effect of alumina crucible on different aspects of the solvent refining of silicon by the Si-Ca-Fe system was investigated in this paper. Ca and Fe were added to Si in a wide range of concentrations (0–20 wt%), and the melt composition change resulting from melt-alumina interactions was studied thermodynamically and experimentally. The ratio of Ca concentration in the final melt to its value in the initial mixture was in the range of 0.17–0.23. On the other hand, a considerable amount of Al was identified in the melt together with CaAl4O7, Ca2Al2SiO7, and CaAl2O4 phases as oxide interaction products. A conceptual mechanism was proposed for the evolution of these products. Then, the segregation behavior of impurities during solidification was studied based on Fe or Ca increment in the system, and B and P removal rates were calculated in particular. The higher the Ca or Fe content were, the higher removal rates were achieved. They were also enhanced by cooling the samples in the furnace rather than quenching from 1493 K (1220 °C). The directional solidification method was also examined, and it showed the best overall removal rate with 94.9% for P and 63% for B, while its impact on B reduction was more than P.