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lurgical treatment producing solar-grade Si (SoG-Si) from metallurgical-grade Si (MG-Si) is a promising method for the manufacturing of low-cost Si solar cells. Among the impurity elements in MG-Si, B is difficult to remove through solidification refining and vacuum melting because of its large segregation coefficient [0.8 at 1687 K (1414 °C)][1] and low vapor pressure.[2] Although processes such as oxidation through H2O-added plasma melting[3,4] and slag treatment[5,6] are currently employed for B removal, there is a strong demand to further reduce the cost of the refining process for manufacturing SoG-Si. Recently, a solvent refining process using Al-Si melt combined with electromagnetic solidification has shown outstanding results in purifying Si more effectively and YUN LEI, Associate Professor, and WENHUI MA and YONGNIAN DAI, Professors, are with the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming 650093, P.R. China, and also with the National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, P.R. China. Contact e-mails: [email protected], [email protected] LUEN SUN, Graduate Student (Master’s), is with the Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, P.R. China. KAZUKI MORITA, Professor, is with the Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. Manuscript submitted March 29, 2015. Article published online November 9, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B

economically.[7,8] Some attempts have also been made to improve B removal based on this solvent refining process, such as using Si-Al-Sn (10-30 mol pct)[9] and Si-Al-Zn (