New Insights into Silicon Purification by Alloying–Leaching Refining: A Comparative Study of Mg–Si, Ca–Si, and Ca–Mg–Si Systems,ACS Sustainable Chemistry & Engineering

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New Insights into Silicon Purification by Alloying–Leaching Refining: A Comparative Study of Mg–Si, Ca–Si, and Ca–Mg–Si Systems
ACS Sustainable Chemistry & Engineering ( IF 7.1 ) Pub Date : 2020-10-13 , DOI: 10.1021/acssuschemeng.0c05564
Mengyi Zhu ₁ , Sheng Ying Yue _{2,

3} , Kai Tang ₄ , Jafar Safarian ₁

Affiliation

In the present work, a comparative study of the silicon alloying–leaching purification process was carried out on the recently developed Mg–Si system, the Ca–Si system, and the novel ternary Ca–Mg–Si system. Insights were provided into the integrated process from aspects of thermodynamic assessment, microstructural analysis, experimental observation, computational simulation, and analytical modeling. The main silicide precipitates of the three Mg–Si, Ca–Si, and Ca–Mg–Si alloys studied were determined as Mg₂Si, CaSi₂, and ternary Ca₇Mg_7.5±δSi₁₄, respectively. Other metallic impurities were found to form complex silicides embedded inside the main precipitate, where P also segregated and precipitated according to the interaction with the alloying elements. All of the impurities were further carried away with the removal of the main precipitates through the subsequent leaching process. It was found that the ternary Ca–Mg–Si alloy exhibits a cleaner leaching process due to the unique crystal structure of Ca₇Mg_7.5±δSi₁₄. A novel cracking–shrinking principle-based kinetics model was developed to further describe the impurity removal process. The segregation behavior of P was also modeled through a thermodynamic approach and Ca was found to have stronger P affinity compared to Mg. It was finally concluded that the novel Ca–Mg–Si ternary alloy system exhibited better performance overall as compared to the other two binary alloys.

中文翻译：

合金浸出精炼提纯硅的新见解：Mg-Si，Ca-Si和Ca-Mg-Si系统的比较研究

在当前的工作中，对最近开发的Mg-Si系统，Ca-Si系统和新型三元Ca-Mg-Si系统进行了硅合金浸提纯化工艺的比较研究。从热力学评估，微观结构分析，实验观察，计算模拟和分析建模等方面对集成过程提供了见解。三个Mg-Si系，硅钙，和Ca-Mg-Si系合金的主要析出物的硅化物所研究确定为镁₂的Si，硅钙₂，和三元的Ca ₇ Mg的_7.5±δ的Si ₁₄，分别。发现其他金属杂质形成嵌入主要沉淀物内部的复杂硅化物，其中P也根据与合金元素的相互作用而偏析和沉淀。通过随后的浸提过程，所有杂质进一步被去除，同时去除了主要沉淀物。据发现，三元的Ca-Mg-Si合金表现出清洁器浸出过程中由于Ca的独特晶体结构₇的Mg _δ7.5±硅₁₄。建立了一种基于开裂-收缩原理的新型动力学模型，以进一步描述杂质去除过程。还通过热力学方法模拟了磷的偏析行为，发现与镁相比，钙具有更强的磷亲和力。最后得出的结论是，与其他两种二元合金相比，新颖的Ca-Mg-Si三元合金体系总体表现出更好的性能。

更新日期：2020-10-26

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