Reaction Mechanism and Kinetics of Boron Removal from Molten Silicon via CaO-SiO{sub 2}-CaCl{sub 2} Slag Treatment and Ammonia Injection

Journal Article · Tue Oct 15 04:00:00 EDT 2019 · Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-019-01639-4· OSTI ID:22933471

Chen, Hui; Yuan, Xizhi ^[1]; Morita, Kazuki ^[2]; Zhong, Yanjun ^[1]; Ma, Xiaodong ^[3]; Chen, Zhiyuan ^[4]; Wang, Ye ^[1]

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1. Sichuan University, School of Chemical Engineering (China)
2. The University of Tokyo, Department of Materials Engineering (Japan)
3. The University of Queensland, School of Chemical Engineering (Australia)
4. Delft University of Technology, Department of Materials Science and Engineering (Netherlands)

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 SiO{sub 2}-46.7 mol pct CaCl{sub 2} 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.

• OSTI ID: 22933471
• Journal Information: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science Journal Issue: 5 Vol. 50; ISSN MTBSEO; ISSN 1073-5615
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMMONIA
BORON
BORON OXIDES
CALCIUM CHLORIDES
CALCIUM OXIDES
CATALYSTS
CONCENTRATION RATIO
FLUID INJECTION
IRON
MASS TRANSFER
REACTION KINETICS
SILICON OXIDES
SLAGS