Thermodynamics of Impurities Removal From Si–Fe Alloy by CaO–Al2O3–SiO2–Na2O Slag Refining

Slag refining of molten Si–Fe alloy was investigated with the ultimate goal of producing silicon suitable for solar cell application. Multiple compositions of quaternary slag of CaO–Al 2 O 3 –SiO 2 –Na 2 O were used to treat Si-20 wt pct Fe alloy at 1300 °C. Partition ratio of B increased with incre...

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Bibliographic Details
Published in:Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2022-12, Vol.53 (6), p.4019-4028
Main Authors: Taposhe, Golam Ismot Ara, Khajavi, Leili Tafaghodi
Format: Article
Language:English
Subjects:
Aluminum oxide
Boron
Calcium oxide
Characterization and Evaluation of Materials
Chemistry and Materials Science
Efficiency
Ferrous alloys
Investigations
Materials Science
Metallic Materials
Metals
Nanotechnology
Optical basicity
Original Research Article
Photovoltaic cells
Semiconductors
Silicon
Silicon dioxide
Slag
Solar cells
Solids
Solvents
Structural Materials
Surfaces and Interfaces
Thermodynamics
Thin Films
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Summary:Slag refining of molten Si–Fe alloy was investigated with the ultimate goal of producing silicon suitable for solar cell application. Multiple compositions of quaternary slag of CaO–Al 2 O 3 –SiO 2 –Na 2 O were used to treat Si-20 wt pct Fe alloy at 1300 °C. Partition ratio of B increased with increasing the slag basicity, and the maximum partition ratio of boron was found to be 4.3. The addition of 10 wt pct Na 2 O results in higher removal of boron. The modified quasichemical model was utilized to compute the activity of silica at 1300 °C which was then used to calculate the borate and phosphate capacities of the slag. A comparative thermodynamic assessment was conducted by establishing a relationship between corrected optical basicity and borate and phosphate capacities. The evaluation showed that lower temperature is favorable for increasing borate and phosphate capacities in slag at particular basicity.
ISSN:1073-5615
1543-1916
DOI:10.1007/s11663-022-02662-8