2018 Fiscal Year Final Research Report

Local structure and properties in multicomponent molten salts

Research Project

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Project/Area Number	16K14443
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Multi-year Fund
Research Field	Metal making/Resorce production engineering
Research Institution	Tohoku University
Principal Investigator	Waseda Yoshio 東北大学, 多元物質科学研究所, 名誉教授 (00006058)
Co-Investigator(Kenkyū-buntansha)	篠田弘造東北大学, 多元物質科学研究所, 准教授 (10311549) 助永壮平東北大学, 多元物質科学研究所, 准教授 (20432859) 柴田浩幸東北大学, 多元物質科学研究所, 教授 (50250824) 打越雅仁東北大学, 多元物質科学研究所, 准教授 (60447191)
Project Period (FY)	2016-04-01 – 2019-03-31
Keywords	高融点金属分離回収 / 廃棄物からのリサイクル / 溶融塩電解 / X線吸収分光
Outline of Final Research Achievements	The purpose of this study was to obtain fundamental knowledge leading to the establishment of the technique of refractory metals recovery from molten salt with electroplating by comparing the local structure in the molten state with the results of the electrolytic recovery experiment. The relationship between the molten salt composition and the melting temperature and the local structure was investigated and clarified based on the data obtained by the in-situ measurement in the high temperature molten state mainly applying X-ray absorption spectroscopy. It has been found that, by using a molten salt of mixed halide composition in which a part of the low melting point fluoride is substituted with chloride, a large structure is decomposed and metal can be recovered even under relatively low temperature conditions.
Free Research Field	物質科学
Academic Significance and Societal Importance of the Research Achievements	これまで回収困難であった高融点金属の回収に溶融塩電解を適用するにあたり、塩組成を調整することによって電解温度の低温化、および得られる電析物の緻密化・平滑化が実現可能という指針を得ることができた。このような成果を挙げるには、多元系試料中の目的金属元素周囲の局所構造を原子レベルで解析可能なX線吸収分光の適用、さらに高温溶融状態におけるその場測定を実施する工夫が重要であり、本研究でそれを実現した。