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Boron removal from metallurgical-grade silicon by CaO–SiO2 slag refining

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Abstract

Boron removal from metallurgical-grade silicon (MG-Si) using CaO–SiO2 slag was studied by employing a medium-frequency electromagnetic induction furnace. The relationship between the optical basicity (Λ) of the CaO–SiO2 slag and the distribution coefficient of boron (L B) was investigated. Consequently, the local minimum and maximum L B values of 0.72 and 1.58 are obtained when Λ = 0.56 and Λ = 0.71, respectively. The boron content in MG-Si decreases gradually with refinement time increasing, down to a minimum value of 4.73 × 10−6. The controlling step in the removal of boron from MG-Si is not the chemical reaction at the interface of the slag and silicon. Instead, the controlling step is a diffusion mass transfer, in which boron impurities diffuse from molten silicon to the interface of the slag and silicon, or B2O3 formed by the chemical reaction diffuses from the slag–silicon interface to molten slag.

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Acknowledgments

This study was financially supported by the National Natural Science Foundation of China (Nos. 51461027 and 51104080).

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Authors and Affiliations

  1. The National Engineering Laboratory for Vacuum Metallurgy and State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, 650093, China

    Kui-Xian Wei, Hai-Fei Lu, Wen-Hui Ma, Yan-Long Li, Ji-Jun Wu & Yong-Nian Dai

  2. Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province and Engineering Research Center for Silicon Metallurgy and Silicon Materials of Yunnan Provincial Universities, Kunming University of Science and Technology, Kunming, 650093, China

    Wen-Hui Ma, Zhao Ding & Yong-Nian Dai

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  1. Kui-Xian Wei
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  2. Hai-Fei Lu
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  3. Wen-Hui Ma
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  4. Yan-Long Li
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  5. Zhao Ding
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  6. Ji-Jun Wu
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  7. Yong-Nian Dai
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Correspondence to Wen-Hui Ma.

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Wei, KX., Lu, HF., Ma, WH. et al. Boron removal from metallurgical-grade silicon by CaO–SiO2 slag refining. Rare Met. 34, 522–526 (2015). https://doi.org/10.1007/s12598-015-0496-3

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  • DOI: https://doi.org/10.1007/s12598-015-0496-3

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