| Project/Area Number |
04650607
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属精錬・金属化学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
YAMAMURA Tsutomu TOHOKU UNIVERSITY,SCHOOL OF ENGINEERING,PROFESSOR, 工学部, 教授 (80005363)
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| Co-Investigator(Kenkyū-buntansha) |
ENDO Mamoru TOHOKU UNIVERSITY,SCHOOL OF ENGINEERING,RESEARCH ASSOCIATE, 工学部, 助手 (30213599)
HONGMIN Zhu TOHOKU UNIVERSITY,SCHOOL OF ENGINEERING,RESEARCH ASSOCIATE, 工学部, 助手 (40216148)
SATO Yuzuru TOHOKU UNIVERSITY,SCHOOL OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (80108464)
杉本 克久 東北大学, 工学部, 教授 (80005397)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1993: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1992: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Neodymium / Molten salts electrolysis / Electrowinning / Refining / Liquid electrode / Uranium / Lanthanides / Current efficiency / ランタニド金属 / 不均化反応 / 液体金属電極 / ランタン / クロノポテンショメトリー / サイクリックボルタンメトリー / 電解機構 / 金属溶解 |
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| Research Abstract |
Present study aimed to devlop a preparation process of pure metallic uranium and lanthanides by means of electrolysis. Molten chlorides waere chosen as the electrolytes because they have lowere melting temperature and weaker corrosiveness to the container materials of the facilities in comparison with with molten fluorides. Neodymiun was intensively studied as the representative of uranium and lanthanides, because it is known for its complexity of the mechanism of electrolysis which is typical of uranium and lanthanides.
In this study, an electrochemical investigation clarified that NdCl_3 is reduced directly to metallic neodymium on gold flag type cathode in the molten eutectic LiCl-KCl bath. Based on the results obtained by the eletrochemical study, the conditions of electrowinning were optimized. Then, electrowinning experiment was done in NdCl_3-LiCl-KCl bath using platinaum plate like cathode at the temperatures of 450 to 650ﾟC.Contrary to the expectation, the deposits on the cathode was not metallic neodymium but only oxychloride of neodymium. To understand the mechanism of oxychloride deposition, the dissolution of neodymium into the LiCl-KCl bath was studied. The solubility of neodymium in the bath was confirmed to be negligibly small. However, the addition of small amount of NdCl_3 into the bath enhanced the loss of solid neodymium into the bath drrastically, and even the loss of solid neodymium increased more than the stoichiometry of the amount predicted by the following disproportionation reaction : NdCl_3+Nd=NdCl_2.
To avoid the neodymium deposits on the cathode during the electrolysis because of disproportionation reaction, the activity of the neodymium was lowered by the use of liquid alloy cathode. Using Cd-Mg alloy as cathode, the neodymium was electrowon at the as high as 95% current efficiency from the NdCl_3-LiCl-KCl bath. Neodymium was separated from Cd-Mg by distilllation.
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