Development of novel recycling technology for rare earths combined wet separation and electrodeposition using ionic liquids

2014 Fiscal Year Final Research Report

• Project/Area Number: 24686101
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Recycling engineering
• Research Institution: Yokohama National University
• Principal Investigator: MATSUMIYA Masahiko 横浜国立大学, 環境情報研究科(研究院), 准教授 (00370057)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: 有価物回収 / イオン液体

Outline of Final Research Achievements

In this study, we developed a novel recycling process of rare earth metals from Nd-Fe-B magnets, which was composed of the following steps: pretreatment, wet separation and electrodeposition using ionic liquids. The leaching ratio of Nd3+ and Fe3+ was 91.5% and 5.8%, respectively. Then, Fe(OH)3 precipitate was generated by adding Ca(OH)2 at pH～4.5 on deironization process. As a result, Fe(OH)3 was perfectly removed by solid-liquid separation and the separation factor of Fe was >99.9%. This result allowed us to demonstrate that the electrodeposition energy of residual Fe was 0 kJ/mol. The electrodeposition of Nd metal was performed in ionic liquids under potentiostatic condition of -3.25V at 393K. As for the Nd deposits, Nd metal layer at the depth of 0.62um was confirmed by XPS analysis. Finally, the total recovery energy of Nd-1t was estimated at 1.8MWh/t, which was extremely low compared with the conventional technology and we contributed to the development of energy-saving process.

Free Research Field

応用電気化学