Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review
The applications of rare earth metals and alloys are becoming increasingly widespread and there is a strong market demand. Currently, most of the production enterprises adopt the fluoride–oxide system for electrolytic preparation of rare earth metals and alloys. The solubility of rare earth oxides i...
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MDPI AG
2024-03-01
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| author | Quan Zhou Jinfa Liao Chunfa Liao Baojun Zhao |
| author_facet | Quan Zhou Jinfa Liao Chunfa Liao Baojun Zhao |
| author_sort | Quan Zhou |
| collection | DOAJ |
| description | The applications of rare earth metals and alloys are becoming increasingly widespread and there is a strong market demand. Currently, most of the production enterprises adopt the fluoride–oxide system for electrolytic preparation of rare earth metals and alloys. The solubility of rare earth oxides in molten salt directly affects the selection of operational parameters in the electrolysis process. When the added amount of RE<sub>2</sub>O<sub>3</sub> is less than its solubility, it leads to a decreased electrolytic efficiency. Conversely, an excessive amount of oxide is prone to settle at the bottom of the electrolytic cell, impeding smooth production. The RE<sub>2</sub>O<sub>3</sub> solubility in the fluoride salt can be represented by the phase equilibrium of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system. The isothermal lines in the primary phase field of rare earth oxide represent the solubility of the oxide in the fluoride salt at the corresponding temperature. This paper outlines the research methods and experimental results on the phase equilibria of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system. The characteristics and existing problems in the current phase equilibrium study are analyzed. The solubility data of RE<sub>2</sub>O<sub>3</sub> are expressed in the forms of ternary and pseudo-binary phase diagrams of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system, providing theoretical guidance for the establishment of an accurate and reliable rare earth electrolysis system database and the optimization of electrolytic processes. |
| first_indexed | 2024-04-24T18:01:07Z |
| format | Article |
| id | doaj.art-060a4579f97c4a69b58db78c238c4611 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-04-24T18:01:07Z |
| publishDate | 2024-03-01 |
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| spelling | doaj.art-060a4579f97c4a69b58db78c238c46112024-03-27T13:54:24ZengMDPI AGMetals2075-47012024-03-0114331410.3390/met14030314Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A ReviewQuan Zhou0Jinfa Liao1Chunfa Liao2Baojun Zhao3School of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaSchool of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaThe applications of rare earth metals and alloys are becoming increasingly widespread and there is a strong market demand. Currently, most of the production enterprises adopt the fluoride–oxide system for electrolytic preparation of rare earth metals and alloys. The solubility of rare earth oxides in molten salt directly affects the selection of operational parameters in the electrolysis process. When the added amount of RE<sub>2</sub>O<sub>3</sub> is less than its solubility, it leads to a decreased electrolytic efficiency. Conversely, an excessive amount of oxide is prone to settle at the bottom of the electrolytic cell, impeding smooth production. The RE<sub>2</sub>O<sub>3</sub> solubility in the fluoride salt can be represented by the phase equilibrium of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system. The isothermal lines in the primary phase field of rare earth oxide represent the solubility of the oxide in the fluoride salt at the corresponding temperature. This paper outlines the research methods and experimental results on the phase equilibria of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system. The characteristics and existing problems in the current phase equilibrium study are analyzed. The solubility data of RE<sub>2</sub>O<sub>3</sub> are expressed in the forms of ternary and pseudo-binary phase diagrams of the RE<sub>2</sub>O<sub>3</sub>-REF<sub>3</sub>-LiF system, providing theoretical guidance for the establishment of an accurate and reliable rare earth electrolysis system database and the optimization of electrolytic processes.https://www.mdpi.com/2075-4701/14/3/314rare earthmolten salt electrolysisphase equilibriumsolubility |
| spellingShingle | Quan Zhou Jinfa Liao Chunfa Liao Baojun Zhao Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review Metals rare earth molten salt electrolysis phase equilibrium solubility |
| title | Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review |
| title_full | Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review |
| title_fullStr | Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review |
| title_full_unstemmed | Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review |
| title_short | Phase Equilibrium Study of Rare Earth Oxide–Fluoride Salt System: A Review |
| title_sort | phase equilibrium study of rare earth oxide fluoride salt system a review |
| topic | rare earth molten salt electrolysis phase equilibrium solubility |
| url | https://www.mdpi.com/2075-4701/14/3/314 |
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