Recycled permanent magnets provide a source for rare earth elements
Rare earth elements (REEs) are crucial for ‘green’ technology applications and demand is growing. Their main use is in permanent magnets made from an alloy of neodymium, iron and boron (NdFeB) for highly efficient motors for hybrid-electric vehicles and wind turbines' generators. However, the REE supply is at risk due to the unpredictable trading policies of China, who owns and exploits the main world reserves. Furthermore, access to these resources is important for the delivery of the European Green Deal, which aims to make Europe carbon neutral by 2050. The REE4EU project developed a closed-loop system from permanent magnet waste to new products. Two novel technologies form the basis of the process. The first, ionic liquid extraction (ILE) enables rare earth elements to be removed from the waste streams in the form of oxalates. The second, high temperature electrolysis (HTE) allows the production of rare earth-alloy starting from rare earth-oxide mixtures obtained after calcination of the rare earth-oxalate mixtures from the ILE process.
A new approach
“The beauty lies in the tailored HTE process, as it eliminates the individual REE-oxides or halide separation and conversion steps existing in the primary (mining) Chinese processing route,” says project coordinator Ana Maria Martinez.” Consequently, the REE4EU technology leads to a more effective and environmentally sustainable process, as many single extraction steps are avoided. These custom-made novel technologies allow rare earth-containing wastes from permanent magnets to be dealt with either as in-process waste generated during permanent magnet manufacture or spent permanent magnets from end-of-life products to produce an intermediate alloy containing the rare earth elements. This product is treated by a continuous casting process called ‘strip casting’, to finally obtain a rare earth master alloy for manufacturing permanent magnets, thereby achieving a complete closed-loop permanent recycling process. “This route highlights the competitive cost and excellent environmental footprint compared to the conventional primary rare earth extraction. In addition, a social impact analysis supports the implementation of the REE4EU process,” Martinez explains. The complete closed-loop permanent magnet recycling process, from rare earth-containing waste to new product in the form of a rare earth permanent magnet has been demonstrated at pilot scale. “This opens up the possibility of securing an important value chain in Europe, giving a promising opportunity to rare earth recycling businesses,” comments Martinez.
Major benefits
Following analysis of the data obtained during the pilot trials, the LCA shows a reduction of the climate change impact by about 50 % and, a reduction of the primary energy consumption by around 35 %, when compared to the current scenario, which is the primary production in China. The project represents a significant breakthrough. “Nobody has previously been able to demonstrate the whole permanent magnet value chain using rare earth-containing waste resources at this scale before,” Martinez points out. REE4EU will help build a new European secondary rare earth-alloy production sector, create new jobs, increase Europe’s independence from imports, and provide raw materials for fast-growing European green technology industries. “By accomplishing this the project is not only fostering competitiveness, but also resource efficiency and environmental benefits as well,” Martinez concludes.
Keywords
REE4EU, waste, permanent magnet, rare earth element, recycling, Ionic Liquid Extraction, High Temperature Electrolysis
