Boron partitioning between SiO2–CaO–MgO slags and liquid silicon at controlled nitrogen potential

During refining of silicon using slag treatment, boron dissolved in the silicon is extracted to a liquid oxide (slag) phase. In this investigation the partitioning of boron between SiO 2 –CaO–MgO slags and liquid silicon was examined at 1873 K over a range of slag compositions and CO–N 2 gas mixtures. It was found that the distribution of boron is strongly dependent on the nitrogen partial pressure as well as the slag composition. The greatest partition ratios were achieved at 0.6 atm CO/0.4 atm N 2 with low silica content in the slag. The concentration of MgO in the slag seems to have little or no impact on the boron partition ratio.