European Rare Earth Magnet Recycling Network

Final Report Summary - EREAN (European Rare Earth Magnet Recycling Network)

REEs and the low-carbon economy
Rare-earth elements (REEs) are essential for the transition to a low-carbon economy. Strong neodymium-iron boron (Nd-Fe-B) permanent magnets are used in motors of electric and hybrid electric cars, in electric bicycles and in wind turbines. For the fabrication of the Nd-Fe-B magnets, large quantities of the REEs neodymium (Nd) and dysprosium (Dy) are required. Because China dominates the rare-earth market, there is a severe supply risk for REEs in Europe.

Tackling the REE crisis
In the new list of Critical Raw Materials published by the European Commission in 2017, the REEs are once more considered as the most critical elements on this list. This reconfirms their criticality status in the 2010 and 2014 lists. To tackle this REE crisis, Europe needs a comprehensive approach which combines three equally important strategies, ranging from (1) primary mining of European REE resources (cf. EU FP7 EURARE project), (2) substitution of REEs by less critical elements, and (3) REE recycling and, respectively, recovery from manufacturing scrap and End-of-Life waste streams and, respectively, industrial process residues.

REE recycling and FP7 EREAN
The FP7 EREAN project (European Rare Earth (Magnet) Recycling Network) focusses on the third strategy to overcome the REE crisis: i.e. REE recycling. With respect to the recycling of REEs from End-of-Life waste streams (and manufacturing scrap), currently still less than 1% of the rare earths are being recycled. The creation of a REE recycling industry in Europe requires many skilled chemists and engineers, who can tackle the barriers to develop fully closed-loop environmentally-friendly flow sheets for recycling of REEs from End-of-Life consumer products. The FP7 MC-ITN EREAN has trained 15 young researchers (12 ESR + 3 ER) in the science and technology of rare earths, with emphasis on the recycling of these elements from Nd-Fe-B permanent magnets. An intensive intersectoral and interdisciplinary collaboration was established in the EREAN consortium, which covered the full materials loop, from urban mine to magnet. EREAN bundled European expertise in a cluster of excellence. The EREAN consortium consisted of 9 Full Partners, with 2 Full Partners from the private sector. 6 companies, including 4 SMEs, were Associated Partners. The project was coordinated by the KU Leuven (Belgium). In FP EREAN both direct and indirect recycling schemes were considered. In direct recycling, old magnets are directly processed into new magnets. Direct recycling is recommended for larger non-oxidised magnets with fairly well-defined concentration limits. For other magnet types, indirect recycling is recommended. Here, the REE content of the magnets is recovered via pyrometallurgical and hydrometallurgical processing routes, and the recovered REEs are separated to pure rare-earth oxides, which can be used for preparation of new magnet alloys.

EREAN’s research challenges
The research challenges of the EREAN included the development of efficient extraction of rare-earth-containing materials from electronic waste scrap, removal of exogen elements (Fe, Ni, B) by pyro/hydrometallurgical methods to produce a concentrate of rare earths, development of new approaches to the efficient separation of REE mixtures, direct electrochemical reduction of REE oxides into metals, and the preparation of new Nd-Fe-B magnets. A life cycle assessment (LCA) was performed to corroborate the environmental gains and to assess the economic impact of recycling. By training the researchers in basic and applied REE sciences, with emphasis on extraction and separation methods and metallurgy, sustainable materials management, recycling methods, life cycle assessment (LCA), and the principles of urban mining, they can become the much needed “rare earthers” for employment in the European REE industry. Concurrently, they have received training in a multitude of soft skills, increasing their employability in the materials recycling and metallurgical industries.

EREAN’s research results
Both the direct and indirect recycling routes start with identification of the magnets in mixed waste streams and selective removal of the Nd-Fe-B material from the scrap. A process was developed to extract >95% of Nd-Fe-B from automotive assemblies using hydrogen gas. Because of the embedding of the magnets in the rotors by epoxy resin, the reaction is slower than compared to hard disk drives. The magnetic properties of new magnets made from the extracted powders were not at the same level of the starting magnets. This may be due to incomplete sintering as a consequence of an increase in oxygen content. Therefore, it was necessary to add some extra neodymium. Recycled sintered magnets with >92% of the magnetic properties compared to the starting material could be prepared. Through microstructure and phase composition tuning by appropriate processing routes, partial substitution of the very critical Nd by the less critical Ce and La was possible.

Different flow sheets were developed to recover the REEs from oxidised magnets, based on roasting at high temperatures, followed by selective leaching of the REEs. The leach residue was a marketable hematite byproduct, which can be used as a high-quality red pigment. As an alternative for roasting at higher temperatures, an electrochemical process was developed, based on the selective anodic dissolution of REEs from Nd-Fe-B magnets. Complete iron removal was possible and iron was recovered as a FeCl3 byproduct. A method was developed to successfully eliminate Co, Ni and B from waste water streams of industrial REE recycling processes. Solvent extraction processes based on ionic liquids were developed as a safer and more environmentally-friendly alternative for the recycling of Nd-Fe-B magnets. Their low flammability, negligible volatility and recyclability make them good candidates for the replacement of conventional organic phases in solvent extraction. Ionic liquid solvent extraction processes were developed for Nd/Dy separation and to separate Co from REEs. The use of undiluted ionic liquids allowed to obtain higher percentages extraction and separation factors compared to conventional solvent extraction processes.

Moreover, several novel extractants were synthesised and investigated for solvent extraction of lanthanides from aqueous solutions. It was investigated how the performance of the extraction process could be tuned by a proper choice of the diluent in which the extractant is dissolved. For the separation of REEs by inorganic ion exchangers, three types of zirconium phosphates were prepared and their performance for the separation of Nd/Dy were tested. Separation factors larger than 250 could be achieved by selecting optimised parameters. Concurrently, separation of REE ions by strong magnetic fields has been explored as an alternative to the separation by solvent extraction and ion exchange.

A consequential LCA study was conducted to assess the reduction in environmental impact of the global REE production for use in Nd-Fe-B magnets. The results illustrate the potential benefits of the introduction of a recycling system, the extent of which depends on: (1) the possible extent of the recycling activities, i.e. the question of how much REE material can be supplied from secondary magnet material sources; (2) the respective processing technologies applied in primary REE production and recycling (and, when direct recycling is included, the magnet production processes) and (3) market mechanisms, i.e. whether and to what extent primary REE production output is reduced as a consequence of the recycling activities.

More info and policy-related aspects?
For further information on the project results and the policy-related aspects, the reader is referred to the EREAN website (http://erean.eu/) and the final EREAN Policy Brief which summarises 6 lessons learned concerning the REE crisis and the EU approach so solve this crisis by, amongst others, a focus on REE recycling (download here: http://etn-demeter.eu/wp-content/uploads/2017/07/Policy-Brief-DEMETER_EREAN_June-2017.pdf)

Final Report Summary - EREAN (European Rare Earth Magnet Recycling Network)

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