Rare-earth element separation

Technological transformation towards a greener society requires the use of certain rare-earth elements, which are continuously listed as critical raw materials by the European Commission. Technosphere mining from industrial secondary wastes and recycling from end-of-life products are considered as an important part of our future rare-earth supply. Our expertise in the highly selective nuclear separation are recently expanded into the separation of rare-earth elements.

European Training Network for Zero-Waste Valorisation of Bauxite Residue (Red Mud) http://etn.redmud.org/

Subproject: Separation of REEs using inorganic metal phosphate ion exchangers

2D/3D metal phosphates (MePO) for selective separation of REEs from acidic bauxite residue leaching solutions and for the separation of individual REEs are developed. The MePO materials are characterised by different experimental methods: XRD (structure), FESEM/EDAX (morphology, chemical composition) and FTIR (nature of functional PO4 groups). The first batch uptake tests are made on synthetic leaching solutions. The REE/M ratios (REE = Sc, Y, Ce, Eu, Yb, M = Al, Fe, Ti, Ca, Mg) of batch uptake in synthetic REE leaching solutions are determined. The solid phase concentrations are analysed by EDAX, solution phase by ICP-MS. The batch sorption isotherms are determined. The most promising materials are tested for column loading and elution of individual REEs. After determining the optimum parameters (e.g. MePO material, leaching solution), loading/elution test are carried out with real leaching solutions. The modelling work on REE sorption and elution for initial flow sheet design is carried out.

SEM-picture of TiP materials used as ion exchanger.

Scanning electron microscope pictures of materials used in REE-separations.

Because China dominates the rare-earth market and is reducing its export quota, there is a very high supply risk for rare earths in Europe. To tackle this rare-earth crisis, Europe needs to invest in primary mining, substitution and, in particular, urban mining/recycling. To date, less than 1% of the rare earths are being recycled, due to, amongst others, a lack of efficient recycling technologies. The creation of a rare-earth recycling industry in Europe urgently requires an "army" of skilled chemists and engineers, who can tackle the barriers to develop fully closed-loop environmentally-friendly recycling flow sheets. EREAN (European Rare Earth (Magnet) Recycling Network) will train 15 young researchers (12 ESR + 3 ER) in the S/T of rare earths, with emphasis on the recycling of these elements from permanent magnets. An intensive intersectoral and interdisciplinary collaboration has been established in the EREAN consortium, which covers the full materials loop, from urban mine to magnet. EREAN will bundle European expertise in a cluster of excellence. Research challenges include 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, new separation methods, direct electrochemical reduction of rare-earth oxides into metals, and the preparation of new magnets. By training the researchers in basic and applied rare-earth sciences, with emphasis on extraction and separation methods and rare-earth metallurgy, sustainable materials management, recycling methods, life cycle assessment (LCA), and the principles of urban mining, they will become the much needed "rare earths" for employment in the growing European rare-earth industry. Concurrently, they will receive training in a multitude of soft skills, increasing their employability in the materials recycling and metallurgical industries.