Abstract In this work, Si-Ca-Mg alloys were made with different compositions and solidification conditions to investigate the impurity segregation and separation performance from Si, especially for the problematic P impurity at several ppmw levels. Varying acid leaching parameters were also employed to investigate the optimized process window. Results indicate that the novel Si-Ca-Mg alloying-leaching system is valid for high P extraction. The ternary intermetallic phase Ca7Mg7.5±δSi14 appears as the main precipitate in all alloys to gather other minor impurities. Rapid cooling significantly reduced the size of precipitates and Si grain, the impurity segregation was also limited. In the acid leaching experiments, HCl is found as the most economical leaching agents among the studied combinations. Smaller particle size promotes the leaching efficiency, but the increment narrows with increasing Ca/Mg ratio. Leaching kinetics of the studied alloys was found following the modified Kroger-Ziegler model based on a cracking-shrinking mechanism. The impurity purification efficiency increases with increasing Ca/Mg mixing ratio, but significantly reduced by casting. An analytical model was developed for ternary alloy system to predict the P segregation and its removal with varying alloy concentration through the thermodynamic approach, which shows good agreements of the experimental results.

中文翻译：

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Si-Ca-mg三元合金化-浸出系统去除Si杂质

摘要 在这项工作中，制备了具有不同成分和凝固条件的 Si-Ca-Mg 合金，以研究杂质从 Si 中的偏析和分离性能，特别是对于几个 ppmw 水平的有问题的 P 杂质。还采用了不同的酸浸参数来研究优化的工艺窗口。结果表明，新型 Si-Ca-Mg 合金化-浸出系统对于高 P 提取是有效的。三元金属间相Ca7Mg7.5±δSi14在所有合金中作为主要沉淀物出现，以收集其他次要杂质。快速冷却显着减小了析出物和硅晶粒的尺寸，杂质偏析也受到限制。在酸浸实验中，发现 HCl 是所研究组合中最经济的浸出剂。较小的粒径促进浸出效率，但增量随着 Ca/Mg 比的增加而变窄。根据基于开裂-收缩机制的修正 Kroger-Ziegler 模型，发现所研究合金的浸出动力学。杂质净化效率随着Ca/Mg混合比的增加而增加，但通过铸造显着降低。建立了三元合金体系的分析模型，通过热力学方法预测了随着合金浓度变化的 P 偏析及其去除，这表明实验结果具有良好的一致性。杂质净化效率随着Ca/Mg混合比的增加而增加，但通过铸造显着降低。建立了三元合金体系的分析模型，通过热力学方法预测了随着合金浓度变化的 P 偏析及其去除，这表明实验结果具有良好的一致性。杂质净化效率随着Ca/Mg混合比的增加而增加，但通过铸造显着降低。建立了三元合金体系的分析模型，通过热力学方法预测了随着合金浓度变化的 P 偏析及其去除，这表明实验结果具有良好的一致性。