Research Progress in Preparation and Purification of Rare Earth Metals
<p>Schematic diagram of molten salt electrolysis.</p> "> Figure 2
<p>Effect of electrolysis temperature (<b>a</b>) and rate of addition (<b>b</b>) on oxygen concentration.</p> "> Figure 3
<p>Effect of casting method on oxygen concentration.</p> "> Figure 4
<p>Schematic diagram of metal thermal reduction.</p> "> Figure 5
<p>Schematic diagram of vacuum distillation.</p> "> Figure 6
<p>Vapor pressures of impurities (<b>a</b>) and rare earth elements (<b>b</b>) at 1600 °C.</p> "> Figure 7
<p>Schematic diagram of hydrogen plasma arc melting.</p> "> Figure 8
<p>Schematic diagram of plasma arc zone melting.</p> "> Figure 9
<p>Schematic diagram of solid state electromigration.</p> ">
Abstract
:1. Introduction
2. Progress in Preparation of Rare Earth Metals
2.1. Molten Salt Electrolysis
2.2. Metal Thermal Reduction
3. Progress in Purification of Rare Earth Metals
3.1. Vacuum Distillation
3.2. Arc Melting
3.3. Zone Melting
3.4. Solid State Electromigration
4. Summary and Prospect
- (1)
- Molten salt electrolysis and metal thermal reduction possess high efficiency and yield, but low purity of rare earth metals and high energy consumption are generally non-negligible.
- (2)
- The preparation process of rare earth metals is mainly a manual operation with low automation degree and severe environmental pollution issue.
- (3)
- Deep purification ability of rare earth metals is insufficient, and the industrialization is limited to the use of vacuum distillation, which is difficult to meet the needs of high technology development.
- (1)
- The impurity concentration of rare earth metal should be further reduced so as to provide high purity starting material for the purification process.
- (2)
- A combination of various purification methods should be chosen to remove the impurities for considering the kinds and uses of rare earth metals.
- (3)
- Purification methods suitable for mass production such as vacuum levitation melting and electron beam melting should be developed and researched.
Author Contributions
Funding
Conflicts of Interest
References
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Liu, H.; Zhang, Y.; Luan, Y.; Yu, H.; Li, D. Research Progress in Preparation and Purification of Rare Earth Metals. Metals 2020, 10, 1376. https://doi.org/10.3390/met10101376
Liu H, Zhang Y, Luan Y, Yu H, Li D. Research Progress in Preparation and Purification of Rare Earth Metals. Metals. 2020; 10(10):1376. https://doi.org/10.3390/met10101376
Chicago/Turabian StyleLiu, Hang, Yao Zhang, Yikun Luan, Huimin Yu, and Dianzhong Li. 2020. "Research Progress in Preparation and Purification of Rare Earth Metals" Metals 10, no. 10: 1376. https://doi.org/10.3390/met10101376