•  
  •  
 

Keywords

rare earth, Neodymium, Magnet, Solvent extraction, corrosion

Document Type

Research Paper

Abstract

Recycling rare earth elements, specifically neodymium from magnet scrap, is crucial for advancing sustainable technologies across various industries. In this research, neodymium was recovered by solvent extraction using a stock solution prepared in 200 mL by dissolving 1 g of neodymium (III) nitrate hexahydrate, Nd(NO3)3.6H2O, in 0.5 M nitric acid. Then, it was mixed with 1 M di-(2-ethylhexyl) phosphoric acid (D2EHPA) in Isopar-L, as the organic phase, and 3 M H2SO4, as the aqueous phase, with an organic/aqueous volume ratio of (1:1). Specifically, the study examined the pH variation of the aqueous phase (from 0.5 to 2). The pH of the solution was measured using a pen-type pH meter, where the stripping agent was HNO3 at a concentration of 6 M. The experiments were conducted using a magnetic stirrer at ambient temperature with an agitation speed of 300 rpm for 24 hours. The concentration of metals was measured using an EDX. The extraction efficiency of neodymium increased from 51.7% at a pH of 0.5 to 82.02% at a pH of 1.5, with a slight decrease observed at pH values of 1.7 and 2. Moreover, samples of Mg-Nd alloy were manufactured with various extractant Nd contents of (1, 3, 4, and 5%). The microstructure of the alloys, both before and after corrosion in 3.5% NaCl, was examined using a scanning electron microscope (SEM). The results indicated that the alloys consisted primarily of the α-Mg phase and the Mg12Nd phase, and that the corrosion resistance increased with the increasing amount of neodymium.

References

C. Burkhardt, S. Van Nielen, M. Awais, F. Bartolozzi, J. Blomgren, P. Ortiz, M. B. Xicotencatl‏, An overview of Hydrogen-assisted (Direct) recycling of Rare earth permanent magnets, J. Magn. Magn. Mater., 588 (2023) 171475. https://doi.org/10.1016/j.jmmm.2023.171475 M. Kaya, An overview of NdFeB magnets recycling technologies, Curr. Opin. Green Sustain. Chem., 46 (2024) 100884. https://doi.org/10.1016/j.cogsc.2024.100884 P. Romano, S. Rahmati, R. Adavodi, G. Clementini, F. Gallo, F. Veglio‏, Study of the kinetics and mechanisms of rare earth elements leaching from end-of-life NdFeB magnets through Hydro-Nd process, Sep. Purif. Technol., 356 (2025) 129850. https://doi.org/10.1016/j.seppur.2024.129850 M. I. Martín, I. García-Díaz, F .A. López, Properties and perspective of using deep eutectic solvents for hydrometallurgy metal recovery, Miner. Eng., 203 (2023) 108306. https://doi.org/10.1016/j.mineng.2023.108306 P. Romano, S. Rahmati, R. Adavodi, G. Clementini, F. Gallo, F. Veglio‏, Study of the kinetics and mechanisms of rare earth elements leaching from end-of-life NdFeB magnets through Hydro-Nd process, Sep. Purif. Technol., 356 (2025) 129850. https://doi.org/10.1016/j.seppur.2024.129850 G. Reisdörfer, D. Bertuol, E. H. Tanabe‏, daniel bertuolb, Eduardo Hiromitsu Tanabe, recovery of neodymium from the magnets of hard disk drives using organic acids, Miner. Eng., 143 (2019) 105938. https://doi.org/10.1016/j.mineng.2019.105938 A. C. NI'AM, Y. H. Liu, Y. F. Wang, S. W. Chen, G. M Chang, S. J. You‏, Recovery of Neodymium from Waste Permanent Magnets by Hydrometallurgy Using Hollow Fibre Supported Liquid Membranes, Solvent Extr. Res. Dev. Jpn., 27 (2020) 69-80. https://doi.org/10.15261/serdj.27.69 S. Prusty, S. Pradhan, S. Mishra, Ionic liquid as an emerging alternative for the separation and recovery of Nd, Sm and Eu using solvent extraction technique-A review, Sustain. Chem. Pharm., 21 (2021) 100434. https://doi.org/10.1016/j.scp.2021.100434 E. Allahkarami, B. Rezai, M. Bozorgmehr, S. Adib‏, Extraction of neodymium (III) from aqueous solutions by solvent extraction with Cyanex® 572, Probl. Miner. Proces., 57 (2021) 127-135. https://doi.org/10.37190/ppmp/136080 S. E. Rizk, R. Gamal, N. E. El-Hefny‏, Insights into non-aqueous solvent extraction of gadolinium and neodymium from ethylene glycol solution using Cyanex 572, Sep. Purif. Technol., 275 (2021) 119160. https://doi.org/10.1016/j.seppur.2021.119160 Villoutreys‏, É. De. Thermodynamic study of the (Ce-Nd)-Fe-B system for new permanent magnets. Ph.D. Thesis, Material chemistry, Sorbonne Université, 2024. https://theses.hal.science/tel-04982279v1 A. Bashiri, A. Nikzad, R. Maleki, M. Asadnia, A. Razmjou‏, Rare earth elements recovery using selective membranes via extraction and rejection, Membranes, 12 (2022) 80. https://doi.org/10.3390/membranes12010080 V. Srivastava, J. Werner, R. Honaker, Design of multi-stage solvent extraction process for separation of rare earth elements, Mining, 3 (2023) 552-578. https://doi.org/10.3390/mining3030031 H. Zhang, Y. Zhao , J. Liu,  J. Xu,  D.  Guo, C. Li, Impact  of  rare  earth  elements  on  micro-galvanic  corrosion  in  magnesium  alloys:  A  comparative  study  of  Mg-Nd  and  Mg-Y  binary  alloys, Int. J. Electrochem. Sci., 18 (2023)100160. http://dx.doi.org/10.1016/j.ijoes.2023.100160 S. Belfqueh, S. Chapron, F. Giusti, S. Pellet-Rostaing, A. Seron, N. Menad, G. Arrachart‏, Selective recovery of rare earth elements from acetic leachate of NdFeB magnet by solvent extraction, Sep. Purif. Technol., 339 (2024) 126701. https://doi.org/10.1016/j.seppur.2024.126701 Y. Zhang, F. Gu, Z. Su, S. Liu, C. Anderson, T. Jiang, Hydrometallurgical Recovery of Rare Earth Elements from NdFeB Permanent Magnet Scrap: A Review, Metals, 10 (2020) 841. https://doi.org/10.3390/met10060841 L. Wang, X. Xu‏, Facile Synthesis of Nd2Fe14B Hard Magnetic Particles with Microwave-Assisted Hydrothermal Method, Molecules, 28 (2023) 7918. https://doi.org/10.3390/molecules28237918 Y. Mehrifar, H. Moqtaderi, F. Golbabaei, S. M. Hamidi, M. Hasanzadeh, S. F. Dehghan, Characterisation of electro-spun nanofibers containing Nd2Fe14B ferromagnetic alloy nanoparticles: A promising potential for the synthesis of new magnetic, J. Alloys Compd., 1007 (2024) 176301. https://doi.org/10.1016/j.jallcom.2024.176301 L. Wang, X. Xu‏, Facile Synthesis of Nd2Fe14B Hard Magnetic Particles with Microwave-Assisted Hydrothermal Method, Molecules, 28 (2023) 7918. https://doi.org/10.3390/molecules28237918 L. G. D Santos, D. D. A. Buelvas, D. F. Valezi, B. L. S. Vicentin, Microstructural and magnetic properties of polyamide-based recycled composites with iron oxide nanoparticles, Magnetism, 5 (2025) 5. https://doi.org/10.3390/magnetism5010005 H. Chen, W. Liu, Z. Guo, T. Yang, H. Wu, Y. Qin, Y. Li, Coercivity enhancement of Nd-La-Ce-Fe-B sintered magnets: Synergistic effects of grain boundary regulation and chemical heterogeneity, Acta Materialia, 235 (2022) 118102 https://doi.org/10.1016/j.actamat.2022.118102 A. Gholizadeh, V. Banihashemi, Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite, J. Am. Ceram. Soc., 106 (2023) 5351-5363. https://doi.org/10.1111/jace.19191 S. A. Ajeel, F. A. Sameer, N. I. AbdulLatif‏, Separation of Aluminium Chloride from White Kaolinite by Slime Leaching Process, Eng. Technol. J., 32 (2014) 2412-0758. https://doi.org/10.30684/etj.32.7A8 D. Talan , Q. Huang, A review of environmental aspects of rare earth element extraction processes and solution purification techniques, Miner. Eng., 179 (2022) 107430. https://doi.org/10.1016/j.mineng.2022.107430 M. De Luccas Dourado and D. G. de Carvalho, Modeling and simulation of samarium and neodymium separation by a solvent extraction process, Braz. J. Chem. Eng., 42 (2025) 413-420. https://doi.org/10.21203/rs.3.rs-3006822/v1 R. Rodríguez Varela, A. Chagnes, K. Forsberg, Third-Phase Formation in Rare Earth Element Extraction with D2EHPA: Key Factors and Impact on Liquid Membrane Extraction Performance, Membranes, 15 (2025) 188. https://doi.org/10.3390/membranes15070188 S. Laguel, M. H. Samar, Elimination of rare earth (neodymium (III)) from water by emulsion liquid membrane process using D2EHPA as a carrier in kerosene, Desalin. Water Treat., 317 (2024) 100214. https://doi.org/10.1016/j.dwt.2024.100214 S. Belfqueh, S. Chapron, F. Giusti, Selective recovery of rare earth elements from acetic leachate of NdFeB magnet by solvent extraction, Sep. Purif. Technol., 339 (2024) 126701. https://doi.org/10.1016/j.seppur.2024.126701 A. Merroune, J. Ait Brahim, B. Achiou, R. Boulif, Behaviours of rare earth elements from industrial wet-process phosphoric acid using di-(2-ethyl-hexyl) phosphoric acid solvent: optimisation and thermodynamic studies, J. Mol. Liq., 367 (2022) 120585 https://doi.org/10.1016/j.molliq.2022.120585 B. Mwewa, M. Tadie, S. Ndlovu, G. S. Simate, Recovery of rare earth elements from acid mine drainage: A review of the extraction methods, J. Environ. Chem. Eng., 10 (2022) 107704. https://doi.org/10.1016/j.jece.2022.107704 Z. Zhang, J. Liu, T. Li, Z. Fu, J. Mao, X. Li, S. Ren‏, Highly efficient and selective separation of dysprosium and neodymium from polyethene glycol 200 solution by non-aqueous solvent extraction with P350, J. Mol. Liq., 380 (2023) 121765. https://doi.org/10.1016/j.molliq.2023.121765 M. E. Reece, A. A. Migdisov, A. E. Williams-Jones, A. C. Strzelecki, L. Waters, H. Boukhalfa, X. Guo‏, Stability of aqueous neodymium complexes in carbonate-bearing solutions from 100-600 °C, Commun. Earth Environ., 6 (2025) 353. https://doi.org/10.1038/s43247-025-02334-w L. Alcaraz , O. Rodríguez‐Largo, Recovery of Rare Earths from End‐of‐Life NdFeB Permanent Magnets from Wind Turbines, Chem. Sus. Chem., 18 (2025) e202402237. https://doi.org/10.1002/cssc.202402237 D. A. Gkika, M. Chalaris, G. Z. Kyzas, Review of methods for obtaining rare earth elements from recycling and their impact on the environment and human health, Processes, 12 (2024)1235. https://doi.org/10.3390/pr12061235 L. Zhang, W. Xiao, G. Li, D. Wang, J. Wu, H. Du, A cleaner and sustainable method for recovering rare earth and cobalt from NdFeB leaching residues, J. Clean. Prod., 422 (2023) 138576.https://doi.org/10.1016/j.jclepro.2023.138576 A. Fayyaz, R. Ali, M. Waqas, U. Liaqat, R. Ahmad, Analysis of rare earth ores using laser-induced breakdown spectroscopy and laser ablation time-of-flight mass spectrometry, Minerals, 13 (2023) 787. https://doi.org/10.3390/min13060787 A. Amidi, S. A. M. Razif, N. A. Jabit, K. S. Ariffin, Characterisation of rare earth elements (REE) from industrial REE waste resources, Mater. Today Proc., 66 (2022) 3140-3143. https://doi.org/10.1016/j.matpr.2022.07.464 Y. Yang, X Zhang, K. Li, L Wang, F. Niu, D. Liu, Y Meng. Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na2CO3 Solution, Minerals, 11 (2021) 952. https://doi.org/10.3390/min11090952 A. Phuruangrat, S. Thongtem, T. Thongtem, Template-free synthesis of neodymium hydroxide nanorods by microwave-assisted hydrothermal process and of neodymium oxide nanorods by thermal decomposition, Ceram. Int., 38 ( 2012) 4075-4079. https://doi.org/10.1016/j.ceramint.2012.01.065 Guo, X. Dissolution and Electrochemical Reduction of Rare Earth Oxides in Fluoride Electrolytes. Ph.D. Thesis, Delft University of Technology, 2021. https://doi.org/10.4233/uuid:79a1f6f1-52d1-48a9-a0df-03c1b1ce0ac6 A. A. Galhoum, B. T. Mohamed, S. S. Abdulmoteleb, Solvent extraction of titanium (IV) from orthophosphoric acid media using Aliquat-336/kerosene and stripping with nitric acid, Hydrometallurgy, 231 (2025) 106403. https://doi.org/10.1016/j.hydromet.2024.106403 A. Lee, A. Naquash, M. Lee, Y. D. Chaniago, H. Lim‏, Exploitation of distillation for energy-efficient and cost-effective environmentally benign process of waste solvents recovery from semiconductor industry, Sci. Total. Environ., 841 (2022) 156743. https://doi.org/10.1016/j.scitotenv.2022.156743 X. Xiang, Y. Wu, Z. Chen, Y. Pan, Y. Ge, Y. Zhang‏, Neodymium-modified Mg-Zn-Zr magnesium alloy as a biodegradable osteogenic implant, iScience, 28 (2025) 112677. https://doi.org/10.1016/j.isci.2025.112677 X. Wei, S. Gao, Q. Le, L. Ren, J. Hu, J. Wu, and T. Wang, Preparation of Mg-Nd alloys by in situ reduction using Nd2O3, J. Alloys Compd., 1004 (2024) 175720 https://doi.org/10.1016/j.jallcom.2024.175720 X. Yan, B. Su, X. Yang, Q. Xu, X. Zhang, J. Wang, Z. Wen, Experimental and simulation investigation of Nd additions on as-cast microstructure and precipitate development in Mg–Nd system alloys, Materials, 15 (2022) 2535. https://doi.org/10.3390/ma15072535 J. Wang, Y. Yuan, T. Chen, L. Wu, X. Chen, and B. Jiang, Multi-solute solid solution behaviour and its effect on the properties of magnesium alloys, J. Magnes. Alloy., 10 (2022) 1786-1820. https://doi.org/10.1016/j.jma.2022.06.015 H. Zhang, Y. Zhao, J. Liu, J. Xu, D. Guo, C. Li, Impact of rare earth elements on micro-galvanic corrosion in magnesium alloys: A comparative study of Mg-Nd and Mg-Y binary alloys, Int. J. Electrochem. Sci., 18 (2023) 100160. https://doi.org/10.1016/j.ijoes.2023.100160 R. K. Abd, A. K. Hussein, L. K. Abbas‏, Synthesis and Characterisation of NiP-TiC-SiC Nanocomposite Coating via Electroless Process on Alumina Substrate, Eng. Technol. J., 41 (2023) 1456-1464. http://doi.org/10.30684/etj.2023.139852.1444 S. R. Areef, Effect of (Zn & Mg) on Corrosion Behaviour of Shape Memory Alloys, Eng. Technol. J., 28 (2010) 5651-5659. https://doi.org/10.30684/etj.28.18.3 J. Liu, Z. Lv, Z. Wu, J. Zhang, C. Zheng, C. Chen, Research progress on the influence of alloying elements on the corrosion resistance of high-entropy alloys, J. Alloys Compd., 1002 (2024) 175394. https://doi.org/10.1016/j.jallcom.2024.175394 H. Liao, M. Wu, D. Deng, W. Zhong, and B. Xiong, Effects of Ti content on the microstructure, mechanical properties and corrosion behaviour of TixZrNb alloys, J. Mater. Res. Technol., 19 (2022) 1433-1443. https://doi.org/10.1016/j.jmrt.2022.05.140

Highlights

At pH ≤ 2, the concentration of rare earth elements and metal ions increased, enhancing the extraction potential. D2EHPA acted as an efficient cation exchanger, releasing H⁺ ions during metal cation uptake. In solvent extraction, precipitated particles promoted rare earth attachment to extractant compounds. The highest neodymium extraction efficiency was achieved at a pH of 1.5. The addition of neodymium to magnesium improved its corrosion resistance.

DOI

10.30684/etj.2025.159446.1948

First Page

835

Last Page

851

Download

Share

COinS