Reaction mechanism and kinetics of boron removal from molten silicon via CaO-SiO2-CaCl2 slag treatment and ammonia injection

Hui Chen, Xizhi Yuan, Kazuki Morita, Yanjun Zhong, Xiaodong Ma, Zhiyuan Chen, Ye Wang*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    14 Citations (Scopus)

    Abstract

    To improve the boron-removal efficiency of metallurgical-grade silicon by increasing the reaction rate, a combined method with the 30 mol pct CaO-23.3 mol pct SiO2-46.7 mol pct CaCl2 slag treatment and ammonia injection at 1723 K to 1823 K was proposed. For 1 hour and at 1823 K, the maximum removal efficiency of boron was 98 pct, and the final boron concentration in silicon decreased to 1.5 ppmw by the present method without the introduction of the iron catalyst. A kinetic model was also established to clarify the reaction mechanism and rate-limiting steps of this complicated boron-removal process. In this model, the rate-limiting step is the mass transfer of boron oxide at the interface between the slag and silicon phase.

    Original languageEnglish
    Pages (from-to)2088-2094
    JournalMetallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science
    Volume50
    Issue number5
    DOIs
    Publication statusPublished - 2019

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