scholarly journals Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1374
Author(s):  
Anna Klemettinen ◽  
Andrzej Żak ◽  
Ida Chojnacka ◽  
Sabina Matuska ◽  
Anna Leśniewicz ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Operating Conditions ◽  
Rare Earth Ion ◽  
Feed Material ◽  
Ndfeb Magnets ◽  
Simplified Approach ◽  
Unit Operations ◽  
Oxidative Roasting ◽  
Hydrochloric And Sulfuric Acids

A simplified approach for rare earth elements leaching from NdFeB (neodymium-iron-boron) magnets was investigated. The possibility of simplifying the magnet recycling process by excluding grinding, milling and oxidative roasting unit operations was studied. Attempts to skip the demagnetization step were also conducted by using whole, non-demagnetized magnets in the leaching process. The presented experiments were conducted to optimize the operating conditions with respect to the leaching agent and its concentration, leaching time, leaching temperature and the form of the feed material. The use of hydrochloric and sulfuric acids as the leaching agents allowed selective leaching of NdFeB magnets to be achieved while leaving nickel, which is covering the magnets, in a solid state. The application of higher leaching temperatures (40 and 60 °C for sulfuric acid and 40 °C for hydrochloric acid) allowed us to shorten the leaching times. When using broken demagnetized magnets as the feed material, the resulting rare earth ion concentrations in the obtained solutions were significantly higher compared to using whole, non-demagnetized magnets.

scholarly journals A study of rare earth ion-adsorption clays: The speciation of rare earth elements on kaolinite at basic pH

2020 ◽  
pp. 105920
Author(s):  
Xu Feng ◽  
Oznur Onel ◽  
McAlister Council-Troche ◽  
Aaron Noble ◽  
Roe-Hoan Yoon ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Ion Adsorption ◽  
Rare Earth Ion

scholarly journals Selective Roasting of Nd–Fe‒B Permanent Magnets as a Pretreatment Step for Intensified Leaching with an Ionic Liquid

2019 ◽  
Vol 6 (1) ◽  
pp. 91-102 ◽  
Author(s):  
Martina Orefice ◽  
Amy Van den Bulck ◽  
Bart Blanpain ◽  
Koen Binnemans
Keyword(s):  
Ionic Liquid ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Permanent Magnets ◽  
Metallic Phase ◽  
Process Step ◽  
Mechanical Removal ◽  
Oxidative Roasting ◽  
Roasting Temperature ◽  
The Rare Earth

AbstractOxidative roasting of Nd–Fe‒B permanent magnets prior to leaching improves the selectivity in the recovery of rare-earth elements over iron. However, the dissolution rate of oxidatively roasted Nd–Fe‒B permanent magnets in acidic solutions is very slow, often longer than 24 h. Upon roasting in air at temperatures above 500 °C, the neodymium metal is not converted to Nd2O3, but rather to the ternary NdFeO3 phase. NdFeO3 is much more difficult to dissolve than Nd2O3. In this work, the formation of NdFeO3 was avoided by roasting Nd–Fe‒B permanent magnet production scrap in argon atmosphere, having an oxygen content of $$ p_{{{\text{O}}_{2} }} \, \le \,10^{ - 20} \;{\text{atm}}, $$pO2≤10-20atm, with the addition of 5 wt% of carbon as an iron reducing agent. For all the non-oxidizing iron roasting conditions investigated, the iron in the Nd–Fe‒B scrap formed a cobalt-containing metallic phase, clearly distinct from the rare-earth phase at microscopic level. The thermal treatment was optimized to obtain a clear phase separation of metallic iron and rare-earth phase also at the macroscopic level, to enable easy mechanical removal of iron prior to the leaching step. The sample roasted at the optimum conditions (i.e., 5 wt% carbon, no flux, no quenching step, roasting temperature of 1400 °C and roasting time of 2 h) was leached in the water-containing ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N]. A leaching time of only 20 min was sufficient to completely dissolve the rare-earth elements. The rare-earth elements/iron ratio in the leachate was about 50 times higher than the initial rare-earth elements/iron ratio in the Nd–Fe‒B scrap. Therefore, roasting in argon with addition of a small amount of carbon is an efficient process step to avoid the formation of NdFeO3 and to separate the rare-earth elements from the iron, resulting in selective leaching for the recovery of rare-earth elements from Nd–Fe‒B permanent magnets.

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets

2016 ◽  
Vol 22 (1) ◽  
pp. 82-86 ◽  
Author(s):  
Susumu Imashuku ◽  
Kazuaki Wagatsuma ◽  
Jun Kawai
Keyword(s):  
Rare Earth ◽  
Electron Microscope ◽  
Hydrochloric Acid ◽  
Scanning Electron Microscope ◽  
Rare Earth Elements ◽  
Luminescence Spectra ◽  
Ndfeb Magnet ◽  
Ndfeb Magnets ◽  
X Ray ◽  
Scanning Electron

AbstractScanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium–iron–boron (NdFeB) and samarium–cobalt (Sm–Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm–Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

Reclaiming rare earth elements from end-of-life products: A review of the perspectives for urban mining using hydrometallurgical unit operations

2015 ◽  
Vol 156 ◽  
pp. 239-258 ◽  
Author(s):  
Cristian Tunsu ◽  
Martina Petranikova ◽  
Marino Gergorić ◽  
Christian Ekberg ◽  
Teodora Retegan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
End Of Life ◽  
Urban Mining ◽  
Unit Operations

scholarly journals Leaching and Recovery of Rare-Earth Elements from Neodymium Magnet Waste Using Organic Acids

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 721 ◽  
Author(s):  
Marino Gergoric ◽  
Christophe Ravaux ◽  
Britt-Marie Steenari ◽  
Fredrik Espegren ◽  
Teodora Retegan
Keyword(s):  
Acetic Acid ◽  
Rare Earth ◽  
Citric Acid ◽  
Solvent Extraction ◽  
Rare Earth Elements ◽  
Organic Acids ◽  
End Of Life ◽  
Partial Solution ◽  
The European Union ◽  
Ndfeb Magnets

Over the last decade, rare-earth elements (REEs) have become critical in the European Union (EU) in terms of supply risk, and they remain critical to this day. End-of-life electronic scrap (e-scrap) recycling can provide a partial solution to the supply of REEs in the EU. One such product is end-of-life neodymium (NdFeB) magnets, which can be a feasible source of Nd, Dy, and Pr. REEs are normally leached out of NdFeB magnet waste using strong mineral acids, which can have an adverse impact on the environment in case of accidental release. Organic acids can be a solution to this problem due to easier handling, degradability, and less poisonous gas evolution during leaching. However, the literature on leaching NdFeB magnets waste with organic acids is very scarce and poorly investigated. This paper investigates the recovery of Nd, Pr, and Dy from NdFeB magnets waste powder using leaching and solvent extraction. The goal was to determine potential selectivity between the recovery of REEs and other impurities in the material. Citric acid and acetic acid were used as leaching agents, while di-(2-ethylhexyl) phosphoric acid (D2EHPA) was used for preliminary solvent extraction tests. The highest leaching efficiencies were achieved with 1 mol/L citric acid (where almost 100% of the REEs were leached after 24 h) and 1 mol/L acetic acid (where >95% of the REEs were leached). Fe and Co—two major impurities—were co-leached into the solution, and no leaching selectivity was achieved between the impurities and the REEs. The solvent extraction experiments with D2EHPA in Solvent 70 on 1 mol/L leachates of both acetic acid and citric acid showed much higher affinity for Nd than Fe, with better extraction properties observed in acetic acid leachate. The results showed that acetic acid and citric acid are feasible for the recovery of REEs out of NdFeB waste under certain conditions.

Selective Recovery of Rare Earth Elements from Dy containing NdFeB Magnets by Chlorination

2013 ◽  
Vol 1 (6) ◽  
pp. 655-662 ◽  
Author(s):  
Yuuki Mochizuki ◽  
Naoto Tsubouchi ◽  
Katsuyasu Sugawara
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Selective Recovery ◽  
Ndfeb Magnets

scholarly journals Comparative Studies of Digestion Techniques for the Dissolution of Neodymium-Based Magnets

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1149
Author(s):  
Mélodie Bonin ◽  
Frédéric-Georges Fontaine ◽  
Dominic Larivière
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Comparative Studies ◽  
Microwave Digestion ◽  
Ndfeb Magnets ◽  
Alkaline Fusion

The digestion of neodymium (NdFeB) magnets was investigated in the context of recycling rare earth elements (i.e., Nd, Pr, Dy, and Tb). Among more conventional digestion techniques (microwave digestion, open vessel digestion, and alkaline fusion), focused infrared digestion (FID) was tested as a possible approach to rapidly and efficiently solubilize NdFeB magnets. FID parameters were initially optimized with unmagnetized magnet powder and subsequently used on magnet pieces, demonstrating that the demagnetization and grinding steps are optional.

scholarly journals Selective acid leaching of rare earth elements from roasted NdFeB magnets

2022 ◽  
Vol 278 ◽  
pp. 119571
Author(s):  
Markku Laatikainen ◽  
Irina Makarova ◽  
Tuomo Sainio ◽  
Eveliina Repo
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Acid Leaching ◽  
Ndfeb Magnets

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

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 716
Author(s):  
Elif Emil Kaya ◽  
Ozan Kaya ◽  
Srecko Stopic ◽  
Sebahattin Gürmen ◽  
Bernd Friedrich
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Spray Pyrolysis ◽  
Ultrasonic Spray Pyrolysis ◽  
Leach Liquor ◽  
Spray Pyrolysis Method ◽  
Ndfeb Magnets ◽  
X Ray ◽  
Ultrasonic Spray ◽  
Pyrolysis Method

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.

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