Solubilities of RE2O3 in REF3-LiF (RE = Nd, Dy) at 1473 K
Solubilities of RE2O3 in REF3-LiF (RE = Nd, Dy) at 1473 K
复制标题
1473 K 时 RE2O3 在 REF3-LiF (RE = Nd, Dy) 中的溶解度
DOI：
10.1007/s40831-022-00617-6
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发表时间：
2022
影响因子：
2.4
通讯作者：
Zhu Hogmin
中科院分区：
文献类型：
--
作者：
Takeda Osamu;Nakano Kiyotaka;Kobayashi Fumiyoshi;Lu Xin;Sato Yuzuru;Zhu Hogmin
开发含稀土废料的回收工艺对于提高稀土金属的资源节约和资源安全性具有重要意义。研究了熔融氟化物和稀土氧化物之间的相平衡，以开发一种基于熔剂重熔法的钕磁体回收新工艺。选用LiF-稀土氟化物（REF 3，RE = Nd，Dy）混合物和稀土氧化物（RE 2 O3，RE = Nd，Dy），采用差热分析和化学平衡法研究了Nd 2 O3-NdF 3-Li 2 O-LiF和Dy 2 O3-DyF 3-Li 2 O-LiF体系的相平衡。结果表明，NdOF、Nd 4 O3 F6、DyOF和Dy 4 O3 F6在1473 K时是稳定的平衡相。在Nd 2 O3在LiF-NdF 3熔体中的溶解过程中，当混合比超过熔体的溶解极限时，Nd 4 O3 F6与熔体共存。同样，当混合比超过熔融LiF-DyF 3的溶解度极限时，形成Dy 4 O3 F6，并且化合物与熔融物共存。在1473 K时，Nd 2 O3在LiF-50 mol%NdF3中的溶解度为7.4 mass%，Dy 2 O3在LiF-50 mol%DyF3中的溶解度为7.6 mass%.由于氟氧化物的溶解速率较慢，因此在实际应用中需要一种提高氟氧化物溶解速率的装置。通过添加少量原生稀土金属，回收过程可用于再生钕磁体废料。图形摘要
The development of a recycling process for rare-earth-containing waste is important for improving the resource conservation and resource security of rare-earth metals. Phase equilibria between the molten fluoride and rare-earth oxide were investigated to develop a novel recycling process for neodymium magnets based on the flux-remelting method. LiF—rare-earth fluoride (REF3, RE = Nd, Dy) mixtures and rare-earth oxides (RE2O3, RE = Nd, Dy) were selected, and the phase equilibria in the Nd2O3−NdF3−Li2O−LiF and Dy2O3−DyF3−Li2O−LiF systems were investigated by differential thermal analysis and chemical equilibrating method. It was revealed that compounds NdOF, Nd4O3F6, DyOF, and Dy4O3F6were stable as an equilibrium phase at 1473 K. In the dissolution of Nd2O3in molten LiF–NdF3, Nd4O3F6formed when the mixing ratio exceeds the solubility limit of the melt and the compound coexists with the melt. In the same manner, Dy4O3F6formed when the mixing ratio exceeds the solubility limit of molten LiF-DyF3and the compound coexists with the melt. At 1473 K, the solubilities of Nd2O3in molten LiF—50 mol% NdF3and Dy2O3in molten LiF—50 mol% DyF3were determined as 7.4 mass% and 7.6 mass%, respectively. An enhancement device for the dissolution rate of oxyfluorides is required for practical applications owing to the slow dissolution rate. The recycling process can be used to regenerate neodymium magnet waste by adding a small amount of virgin rare-earth metals.Graphical Abstract