Si-Sn合金精炼-定向凝固过程硅的分离和提纯

Separation and purification of silicon by combined Si-Sn alloy refining and directional solidification process

采用Sn-Si熔析体系,利用工业规模多晶硅铸锭炉通过控制温度梯度和热场上移速率进行定向凝固处理,研究硅锭的形貌特征、组织结构和提纯效果。结果表明:在定向凝固过程中析出了连续密实的硅晶,且晶体硅与金属熔析剂之间形成了平坦稳定的相界面,实现晶体硅与金属熔析剂的有效分离。晶体硅经过混酸酸洗后,总金属杂质含量由58.3×10-6降低为7.6×10-6,去除率可以达到87%;非金属P含量由50.12×10-6降低为8.48×10-6,去除率大于80%。因此,Si-Sn合金精炼与定向凝固过程复合,解决了硅与金属熔析剂的有效分离问题,同时也实现了杂质的高效去除。

The directional solidification of Si-Sn melt was carried out by controlling the temperature gradient and the moving velocity of thermal field in the ingot furnace. The morphology characteristics, structure and purification effect of the silicon ingot were studied. The results indicate that the growth of bulk Si is achieved from Si-Sn melt, and a flat and stable phase interface forms between the silicon and solvent by directional solidification, resulting in an effective separation. Meanwhile, purification of the refined Si by acid-leaching shows that metallic impurities decrease from 58.3× 10^-6 to 7.6×10^-6, and the removal rate reaches 87%. Non-metallic P content decreases from 50.12×106^-6 to 8.48 ×10^-6, and the removal rate is over 80%. Therefore, not only the effective separation of silicon and solvent, but also the efficient removal of impurities is realized through Sn-Si alloy refining and directional solidification process.