Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution
Rare earths dissolved in carbonate solutions exhibit a metastable state. During the period of metastability, rare earths dissolve stably without precipitation. In this paper, neodymium was chosen as a representative rare earth element. The effects of additional NaCl and CO<sub>2</sub> on...
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MDPI AG
2021-08-01
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| author | Youming Yang Xiaolin Zhang Kaizhong Li Li Wang Fei Niu Donghui Liu Yuning Meng |
| author_facet | Youming Yang Xiaolin Zhang Kaizhong Li Li Wang Fei Niu Donghui Liu Yuning Meng |
| author_sort | Youming Yang |
| collection | DOAJ |
| description | Rare earths dissolved in carbonate solutions exhibit a metastable state. During the period of metastability, rare earths dissolve stably without precipitation. In this paper, neodymium was chosen as a representative rare earth element. The effects of additional NaCl and CO<sub>2</sub> on the metastable state were investigated. The metastable state can be controlled by adding NaCl to the Na<sub>2</sub>CO<sub>3</sub> solution. Molecular dynamics studies indicated that the Cl<sup>−</sup> provided by the additional NaCl partially occupied the coordination layer of Nd<sup>3+</sup>, causing the delayed formation of neodymium carbonate precipitation. In addition, the additional NaCl decreased the concentration of free carbonate in the solution, thereby reducing the behavior of free contact between carbonate and Nd, as well as resulting in the delay of Nd precipitate formation. Consequently, the period of the metastable state was prolonged in the case of introduction of NaCl. However, changing the solution environment by introducing CO<sub>2</sub> can destroy the metastable state rapidly. Introduction of CO<sub>2</sub> gas significantly decreased the CO<sub>3</sub><sup>2−</sup> content in the solution and increased its activity, resulting in an increase of the free CO<sub>3</sub><sup>2−</sup> concentration of the solution in the opposite direction. As a result, the precipitation process was accelerated and the metastable state was destroyed. It was possible to obtain a large amount of rare earth carbonate precipitation in a short term by introducing CO<sub>2</sub> into the solution with dissolved rare earths in the metastable state to achieve rapid separation of rare earths without introducing other precipitants during the process. |
| first_indexed | 2024-03-10T07:24:45Z |
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| last_indexed | 2024-03-10T07:24:45Z |
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| spelling | doaj.art-0925a9aa768b47d8bac11d7e033a06012023-11-22T14:21:02ZengMDPI AGMinerals2075-163X2021-08-0111995210.3390/min11090952Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> SolutionYouming Yang0Xiaolin Zhang1Kaizhong Li2Li Wang3Fei Niu4Donghui Liu5Yuning Meng6Faculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaFaculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaFaculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaCollege of Vanadium and Titanium, Panzhihua University, Panzhihua 617000, ChinaFaculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaFaculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaFaculty of Materials Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou 341000, ChinaRare earths dissolved in carbonate solutions exhibit a metastable state. During the period of metastability, rare earths dissolve stably without precipitation. In this paper, neodymium was chosen as a representative rare earth element. The effects of additional NaCl and CO<sub>2</sub> on the metastable state were investigated. The metastable state can be controlled by adding NaCl to the Na<sub>2</sub>CO<sub>3</sub> solution. Molecular dynamics studies indicated that the Cl<sup>−</sup> provided by the additional NaCl partially occupied the coordination layer of Nd<sup>3+</sup>, causing the delayed formation of neodymium carbonate precipitation. In addition, the additional NaCl decreased the concentration of free carbonate in the solution, thereby reducing the behavior of free contact between carbonate and Nd, as well as resulting in the delay of Nd precipitate formation. Consequently, the period of the metastable state was prolonged in the case of introduction of NaCl. However, changing the solution environment by introducing CO<sub>2</sub> can destroy the metastable state rapidly. Introduction of CO<sub>2</sub> gas significantly decreased the CO<sub>3</sub><sup>2−</sup> content in the solution and increased its activity, resulting in an increase of the free CO<sub>3</sub><sup>2−</sup> concentration of the solution in the opposite direction. As a result, the precipitation process was accelerated and the metastable state was destroyed. It was possible to obtain a large amount of rare earth carbonate precipitation in a short term by introducing CO<sub>2</sub> into the solution with dissolved rare earths in the metastable state to achieve rapid separation of rare earths without introducing other precipitants during the process.https://www.mdpi.com/2075-163X/11/9/952neodymiummetastable statemaintenanceinduced precipitation |
| spellingShingle | Youming Yang Xiaolin Zhang Kaizhong Li Li Wang Fei Niu Donghui Liu Yuning Meng Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution Minerals neodymium metastable state maintenance induced precipitation |
| title | Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution |
| title_full | Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution |
| title_fullStr | Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution |
| title_full_unstemmed | Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution |
| title_short | Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na<sub>2</sub>CO<sub>3</sub> Solution |
| title_sort | maintenance of the metastable state and induced precipitation of dissolved neodymium iii in an na sub 2 sub co sub 3 sub solution |
| topic | neodymium metastable state maintenance induced precipitation |
| url | https://www.mdpi.com/2075-163X/11/9/952 |
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