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Article

NdFeB Magnets Recycling Process: An Alternative Method to Produce Mixed Rare Earth Oxide from Scrap NdFeB Magnets

1
IME Process Metallurgy and Metal Recycling, RWTH Aachen University, 52056 Aachen, Germany
2
Department of Metallurgical & Materials Engineering, Istanbul Technical University, 34469 Istanbul, Turkey
3
Department of Materials Science and Technology, Turkish-German University, 34820 Istanbul, Turkey
4
Department of Mechatronics Engineering, Istanbul Technical University, 34469 Istanbul, Turkey
*
Author to whom correspondence should be addressed.
Academic Editors: Fernando Castro and Felix A. Lopez
Metals 2021, 11(5), 716; https://doi.org/10.3390/met11050716
Received: 19 March 2021 / Revised: 16 April 2021 / Accepted: 26 April 2021 / Published: 27 April 2021
Neodymium iron boron magnets (NdFeB) play a critical role in various technological applications due to their outstanding magnetic properties, such as high maximum energy product, high remanence and high coercivity. Production of NdFeB is expected to rise significantly in the coming years, for this reason, demand for the rare earth elements (REE) will not only remain high but it also will increase even more. The recovery of rare earth elements has become essential to satisfy this demand in recent years. In the present study rare earth elements recovery from NdFeB magnets as new promising process flowsheet is proposed as follows; (1) acid baking process is performed to decompose the NdFeB magnet to increase in the extraction efficiency for Nd, Pr, and Dy. (2) Iron was removed from the leach liquor during hydrolysis. (3) The production of REE-oxide from leach liquor using ultrasonic spray pyrolysis method. Recovery of mixed REE-oxide from NdFeB magnets via ultrasonic spray pyrolysis method between 700 °C and 1000 °C is a new innovative step in comparison to traditional combination of precipitation with sodium carbonate and thermal decomposition of rare earth carbonate at 850 °C. The synthesized mixed REE- oxide powders were characterized by X-ray diffraction analysis (XRD). Morphological properties and phase content of mixed REE- oxide were revealed by scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX) analysis. To obtain the size and particle size distribution of REE-oxide, a search algorithm based on an image-processing technique was executed in MATLAB. The obtained particles are spherical with sizes between 362 and 540 nm. The experimental values of the particle sizes of REE- oxide were compared with theoretically predicted ones. View Full-Text
Keywords: rare earth elements; recycling; NdFeB; magnet; ultrasonic spray pyrolysis rare earth elements; recycling; NdFeB; magnet; ultrasonic spray pyrolysis
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MDPI and ACS Style

Kaya, E.E.; Kaya, O.; Stopic, S.; Gürmen, S.; Friedrich, B. NdFeB Magnets Recycling Process: An Alternative Method to Produce Mixed Rare Earth Oxide from Scrap NdFeB Magnets. Metals 2021, 11, 716. https://doi.org/10.3390/met11050716

AMA Style

Kaya EE, Kaya O, Stopic S, Gürmen S, Friedrich B. NdFeB Magnets Recycling Process: An Alternative Method to Produce Mixed Rare Earth Oxide from Scrap NdFeB Magnets. Metals. 2021; 11(5):716. https://doi.org/10.3390/met11050716

Chicago/Turabian Style

Kaya, Elif E., Ozan Kaya, Srecko Stopic, Sebahattin Gürmen, and Bernd Friedrich. 2021. "NdFeB Magnets Recycling Process: An Alternative Method to Produce Mixed Rare Earth Oxide from Scrap NdFeB Magnets" Metals 11, no. 5: 716. https://doi.org/10.3390/met11050716

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