Article
Materials Science, Multidisciplinary
Pankaj Kumar Choubey, Nityanand Singh, Rekha Panda, Rajesh Kumar Jyothi, Kyoungkeun Yoo, Ilhwan Park, Manis Kumar Jha
Summary: This study explores the recovery of rare earth metals from discarded magnets, with a process including demagnetization, pre-treatment, and hydrometallurgical processing. The results show successful recovery of Nd, Pr, and Dy, with solvent extraction achieving partial separation of REMs and Fe. However, the multistage separation required for this process may not be economically feasible.
Article
Thermodynamics
Daisuke Noguchi, Osamu Takeda, Taichi Abe, Hongmin Zhu, Satoshi Sugimoto
Summary: The activity of Nd and Dy in molten alloys was measured and compared with their activities in ideal solutions. The results showed that the presence of B in the alloys did not significantly affect the activity of Nd, while the activity of Dy was similar to that in ideal solutions. These findings are consistent with the latest phase diagram studies.
THERMOCHIMICA ACTA
(2022)
Article
Chemistry, Applied
Xiaolian Liu, Mengjie Pan, Pei Zhang, Tianyu Ma, Lizhong Zhao, Lingwei Li
Summary: Homogeneous substitution of Dy for Nd in the 2:14:1 phase can enhance coercivity but reduce remanence. A comparative study showed that multi-main-phase magnet with inhomogeneous Dy distribution has better magnetic properties and thermal stability than single-main-phase magnet with homogeneous Dy distribution. The multi-main-phase magnet exhibited higher coercivity, remanence, and energy product at room temperature and over a wide temperature range.
JOURNAL OF RARE EARTHS
(2021)
Article
Electrochemistry
Kenji Kawaguchi, Toshiyuki Nohira
Summary: In this study, we investigated the electrochemical behavior of Dy alloying with Fe in molten LiF-CaF2-DyF3 and successfully recycled Dy and Nd from Dy-doped Nd-Fe-B magnet scraps. The results showed that Dy metal and solid Dy-Fe alloys can be formed by potentiostatic electrolysis, and the equilibrium potentials of different Dy-Fe alloys were determined.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2023)
Article
Materials Science, Multidisciplinary
Namhun Kwon, Jong-Soo Byeon, Hyun Chul Kim, Sung Gue Heo, Soong Ju Oh, Sang-hoon Choi, Seok-Jun Seo, Kyoung-Tae Park
Summary: The study focused on deoxidizing Ti scrap through electrolytic refining and chemical reaction with MgCl2 molten salt electrolysis, resulting in an optimized process for reducing oxygen concentration. By controlling conditions and parameters, a more efficient deoxidation was achieved.
Article
Chemistry, Physical
Zhiming Dai, Kai Li, Zhenhua Wang, Wei Liu, Zhidong Zhang
Summary: Heavy rare-earth elements play an important role in the preparation of permanent magnets. This study investigates the phase composition and magnetization reversal mechanism of the Nd-Dy-Fe-B multicomponent system. It is found that substituting Nd with Dy suppresses certain phases and favors the formation of Nd2Fe14B phase. The study also reveals the influence of magnetic properties of grain boundaries on magnetization reversal.
Article
Materials Science, Multidisciplinary
Xianshuang Xia, Xu Tang, Yeyuan Du, Haichen Wu, Jinyun Ju, Lian Wu, Renjie Chen, Wenzong Yin, Lanting Zhang, Aru Yan
Summary: High coercivities and excellent thermal stability were achieved in hot-deformed Nd-Fe-B magnets through intergranular addition of alloy powders, with a low consumption of rare-earth elements.
Article
Materials Science, Multidisciplinary
Sun-Woo Nam, Sang-Min Park, Mohammad Zarar Rasheed, Myung-Suk Song, Do-Hyang Kim, Taek-Soo Kim
Summary: This study investigated the impact of the Dy2Fe17 phase on the extraction of Dy from Nd-Dy-Fe-B magnet in liquid Mg. The Dy2Fe17 phase was found to act as an obstacle in the extraction process, limiting the extraction efficiency of Dy.
Article
Materials Science, Multidisciplinary
Ryota Nakazawa, Kosuke Noguchi, Yoshinao Kobayashi
Summary: This study explored the method of enhancing the coercivity of Nd-Fe-B magnets at high temperatures by measuring the oxygen solubility in molten alloys and deriving the standard Gibbs energies for oxygen dissolution. Results showed that the affinity between oxygen and the molten alloy increased with higher dysprosium concentration, leading to an estimation of oxygen solubility in the Nd-rich phase based on experimental data.
MATERIALS TRANSACTIONS
(2022)
Article
Chemistry, Physical
Xianshuang Xia, Guantong Wei, Lian Wu, Yeyuan Du, Xu Tang, Jinyun Ju, Haichen Wu, Renjie Chen, Wenzong Yin, Aru Yan
Summary: To improve the utilization of heavy rare-earth resources in Nd-Fe-B magnets, a dual alloy process was used to implement intergranular diffusion of DyF3 aided by nano-Cu. The addition of 0.2 wt% nano-Cu resulted in higher coercivity increment and maintained high remanence compared to Cu-free magnets. The presence of nano-Cu facilitated the dissolution and infiltration of bulky Dy-rich phase into adjacent powder flakes. The higher Dy concentrations in the main phase and grain boundary phase of Cu-containing magnets contributed to the enhancement of coercivity.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Inorganic & Nuclear
Pankaj Kumar Parhi, Pramila Kumari Misra, Rajesh Kumar Jyothi
Summary: The Nd-Fe-B permanent magnet was processed using a hydrometallurgical approach to recover neodymium. The leaching kinetics of neodymium using dilute HCl was studied, and the process optimization was investigated. The obtained leach liquor was used for the recovery of Fe2O3 using slaked lime, and a bifunctional ionic liquid was introduced for the extraction of REMs (Nd and Pr) from the solution. The enriched neodymium oxalate was obtained through calcination of the stripping circuit product.
INORGANIC CHEMISTRY COMMUNICATIONS
(2023)
Article
Engineering, Chemical
Martina Orefice, Koen Binnemans
Summary: The study successfully recovered valuable metals neodymium and dysprosium from Nd-Fe-B scrap using molten pyridine hydrochloride, and then conducted non-aqueous solvent extraction at high temperature using molecular extractants or ionic liquids to improve efficiency.
SEPARATION AND PURIFICATION TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Ryota Nakazawa, Kosuke Noguchi, Yoshinao Kobayashi
Summary: Oxidation of the Nd-rich phase in Nd-Fe-B magnet alloys is known to deteriorate their coercivity. This study measured the oxygen solubility in Nd-Fe-B alloy at 1673 K and analyzed the effect of boron concentration on the affinity between oxygen and the alloy. The addition of boron was found to decrease the affinity between oxygen and the alloy, and a method to suppress oxygen dissolution during the manufacturing process was suggested.
MATERIALS TRANSACTIONS
(2022)
Article
Materials Science, Multidisciplinary
Wei Tang, Gaoyuan Ouyang, Baozhi Cui, Jing Wang, Kevin W. Dennis, Matthew J. Kramer, Iver E. Anderson, Jun Cui
Summary: The study explores the impact of grain size on magnetic and mechanical properties of Dy-free Nd-Fe-B sintered magnets, revealing that reducing grain size can enhance magnetic properties and thermal stability. However, controlling Oxygen content is crucial in balancing magnetic and mechanical properties.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Z. Wang, T. T. Sasaki, Y. Une, T. Ohkubo, K. Hono
Summary: Record-breaking high coercivity is achieved in Dy-free sintered magnets by separately diffusing Dy70Cu30 and Pr68Cu32 eutectic alloys. The low Dy content sample exhibits a high coercivity of 2.8 T and an excellent temperature coefficient of coercivity. The unique presence of a uniform Dy-rich shell and enriched Pr near the surface of Nd2Fe14B grains strengthens the anisotropy field, resulting in the high coercivity without alloying Dy to the initial magnet.
