在1550℃下将CaO-SiO2-Al2O3三元渣与Sn-Si合金混合精炼，降温熔析去除工业硅中的杂质B，考察了渣系光学碱度及合金组成对B去除的影响及作用机理. 结果表明，渣系光学碱度增大，BO1.5的活度系数降低明显，增加了B的分配系数，即增强了精炼效果. Sn-Si合金中Sn比例从0增至70%时，B在渣相与合金相间的分配系数从3.16提高至13.8，硅中B含量最低为0.89′10-6，最高除硼率为93.3%；当Sn比例大于30%时，合金粘度大幅降低，B的分配系数提高；当Sn比例为70%、合金粘度为0.61 mPa×s时，渣系CaO-SiO2-20%Al2O3与CaO-SiO2-40%Al2O3精炼工业硅所得最大B分配系数分别为10.1和12.3.

Sn-Si alloy was refined for removal of boron by composite solvent refining with CaO-SiO2-Al2O3 slag at 1550℃, and the effects of optical basicity of slag and alloy composition on the removal of B and refining mechanism were examined. The results showed that with increasing of the optical basicity, the activity coefficient of BO1.5 decreased obviously, the partition ratio of B increased, leading to the enhancement of refining. When the content of Sn in the alloy increased from 0 to 70%, the partition ratio of B increased from 3.16 to 13.8, the lowest content of B was 0.89′10-6, and the highest removal rate of 93.3% achieved. When the content of Sn was over 30%, the viscosity of Sn-Si alloy substantially decreased, resulting in rising of the partition ratio of B. When the content of Sn was 70% and the viscosity of alloy 0.61 mPa×s, the highest values of partition ratio of B in both CaO-SiO2-20% Al2O3 and CaO-SiO2-40% Al2O3 slag systems were 10.1 and 12.3, respectively.