Development of Innovative Refining Processes for Solar Grade Silicon by Alloying and Flux Treatment

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H02409
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metal making/Resorce production engineering
• Research Institution: The University of Tokyo
• Principal Investigator: Morita Kazuki 東京大学, 大学院工学系研究科(工学部), 教授 (00210170)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 反応・分離・精製 / シリコン / フラックス / 凝固精製 / 合金化

Outline of Final Research Achievements

Innovative silicon purification process for solar grade silicon production to remove B and P most effectively by solvent refining process combined with flux treatment was optimized. Effective B removal condition for low temperature solidification refining with slag treatment was evaluated by measuring the activity coefficient (thermodynamic stability of B) for various alloy composition followed by the slag refining examination.
In addition, possibility of the flux dephosphorization by the reduction reaction (instead of normal oxidation reaction) was confirmed by changing silicon alloy composition and flux system. Furthermore, highly effective dephosphorization was attained by solidification refining after the slag treatment.

Free Research Field

金属生産工学

Academic Significance and Societal Importance of the Research Achievements

種々の溶媒組成において溶融Si合金中のB、Pの熱力学的性質を明らかにすることで、冶金学的手法の組み合わせを最適化することにより、高生産性低コストの冶金学的手法により太陽電池用シリコンの精製が実現可能であることが示された。現在未だ主流であるガス化精製法に代わる高効率高生産性冶金学的手法への展開の可能性があらためて示された。