Boron (B) and phosphorus (P) are the most problematic impurities to be removed in the production of solar-grade silicon by the metallurgical process. In this work, the distribution of B and P between CaO-(La₂O₃)-SiO₂ slags and Si-10 mass pct Sn melt was experimentally studied. B distribution coefficient increased from 2.93 in binary CaO-SiO₂ slag to 3.33 and 3.65 with 2 and 10 mass pct La₂O₃ additions, respectively. In the followed acid-leaching experiments, the slag-treated Si-Sn alloys exhibited higher B and P removal than that of the initial alloy without slag treatment. Molecular dynamics simulations were performed to study the effect of La₂O₃ addition on the slag structural and transport properties. A novel oxygen classification method was proposed to distinguish the different structural roles of La and Ca in the CaO-La₂O₃-SiO₂ system. It was found that La³⁺ prefers to stay in the depolymerized region, mostly connects with 6-7 non-bridging oxygen, and requires a weak charge compensation with Ca²⁺. Possible silicothermic reduction was evaluated to discuss the slag chemistry and the mass transfer between slag and metal phase. A thermodynamic model was derived to theoretically study the alloying effect on impurity distribution in slag refining where positive interaction coefficient and high alloying concentration were found most beneficial to improve the impurity removal.

硼 (B) 和磷 (P) 是在通过冶金工艺生产太阳能级硅时需要去除的最有问题的杂质。在这项工作中，B 和 P 在 CaO-(La ₂ O ₃ )-SiO ₂渣和 Si-10 质量 pct Sn 熔体之间的分布进行了实验研究。B 分配系数从二元 CaO-SiO ₂渣中的2.93增加到 3.33 和 3.65 ，分别添加了 2 和 10 质量 pct La ₂ O ₃。在随后的酸浸实验中，经渣处理的 Si-Sn 合金表现出比未经渣处理的初始合金更高的 B 和 P 去除率。进行分子动力学模拟以研究 La ₂ O 的影响₃添加对炉渣结构和输送性能的影响。提出了一种新的氧分类方法来区分La和Ca在CaO-La ₂ O ₃ -SiO ₂体系中的不同结构作用。发现La ³⁺更喜欢停留在解聚区，大多与6-7非桥连氧连接，需要与Ca ²⁺进行弱电荷补偿. 评估可能的硅热还原以讨论炉渣化学和炉渣与金属相之间的传质。推导出热力学模型，从理论上研究合金化对渣精炼中杂质分布的影响，发现正相互作用系数和高合金化浓度最有利于提高杂质去除率。