Utilization of waste containing rare-earth elements

Герасимова, Л. Г.; Nikolaev, A. I.; Маслова, М. В.; Okhrimenko, R. F.

doi:10.1134/s0040579510050301

Cited by 6 publications

(4 citation statements)

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“…Figure 5 The REEs extracted into the strip solution from the scrap magnets were then precipitated with oxalic acid, followed by filtration, drying, and annealing steps. In comparison, the traditional approaches of utilizing precipitation result in low recovery and the recovered REE may contain significant levels of non-REEs such as Fe and Co. 29,30 It is also difficult to dispose of hazardous wastes. The use of equilibrium-limited solvent extraction would require a large number of stages to produce highly pure REEs suitable for reuse.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction

Kim

Powell

Delmau

et al. 2015

Environ. Sci. Technol.

114

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The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

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Section: Environmental Science and Technologymentioning

confidence: 99%

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction

Kim

Powell

Delmau

et al. 2015

Environ. Sci. Technol.

114

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“…The optimal approach for recycling of a NdFeB magnet should be reusing it in its current shape, but this option is only suitable for the large and easily accessible magnets . In the current industrial application, NdFeB scrap is recovered via hydrometallurgy including many wet steps, as well as two high-temperature steps (calcination and electrolysis) to generate new REs metals. ,− However, the obtained molten chlorides can be directly processed with electrolysis to prepare metals by the technology proposed in this study, which is obviously of low energy consumption. An overview of the comparison between the proposed route and hydrometallurgical route for NdFeB recycling is given in Table .…”

Section: Resultsmentioning

confidence: 99%

“…Currently, the traditional route for extraction of rare earths from permanent magnets is via hydrometallurgical technology. − First, the magnet scrap is preprocessed to remove organic residues and is then dissolved in strong mineral acids. Iron is precipitated as Fe(OH) 3 to be removed by charging a strong alkali solution.…”

Section: Introductionmentioning

confidence: 99%

Selective Extraction of Rare Earth Elements from NdFeB Scrap by Molten Chlorides

Hua

Wang

et al. 2014

ACS Sustainable Chem. Eng.

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With rapid growth in the use of NdFeB magnets and growing concerns for environmental protection as well as conservation of rare earths (REs), the recycling of NdFeB magnet scrap is becoming a hot issue for current society. In this study, it is demonstrated that the rare earths in a NdFeB magnet can be selectively extracted using molten MgCl 2 −KCl salts at temperatures of 600−1200°C. After crushing to granules, the scrap was subjected to molten chlorides in a dry argon atmosphere. The reaction process between NdFeB scrap and molten MgCl 2 −KCl was directly observed using a high-temperature contact angle measuring instrument to clarify the phenomena that occur when rare earth chlorides are formed in situ. Furthermore, the effects of reaction temperature, holding time, and mass ratio of MgCl 2 / NdFeB were investigated to transform REs in the scrap to RECl 3 as completely as possible. The reaction products were examined with the necessary analytical techniques including SEM, EDS, XRD, and ICP. The overall extraction efficiency for REs was found to be more than 90% under the optimum operating conditions. The obtained RECl 3 in the molten MgCl 2 −KCl can be processed with molten salt electrolysis for the direct production of Mg−Nd alloy.

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“…Meanwhile, sulfate medium is often used in hydrometallurgical processing of complex rare metal ore and man-made materials for the concentration of crystal hydrates of simple or double lanthanide sulfates, difficultly soluble in the corresponding aqueous phases, and their separation from other elements [16][17][18][19]. Traditional methods of the conversion of such diffi cultly soluble REE sulfate concentrates to soluble or potentially soluble salts (hydroxides, carbonates, or nitrates) are very unproductive and cumbersome.…”

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confidence: 99%

Extraction of ions of rare earth elements with monocarboxylic acids from sulfate media

Yakubovich

2012

Russ J Appl Chem

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Utilization of waste containing rare-earth elements

Cited by 6 publications

References 0 publications

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction

Selective Extraction of Rare Earth Elements from NdFeB Scrap by Molten Chlorides

Extraction of ions of rare earth elements with monocarboxylic acids from sulfate media

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