An EU-funded initiative has developed an innovative rare earth alloys production process from secondary rare earth-containing resources.
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 enables rare earth elements to be removed from the waste streams in the form of oxalates.
The second, high temperature electrolysis allows the production of rare earth-alloy starting from rare earth-oxide mixtures obtained after calcination of the rare earth-oxalate mixtures from the ionic liquid extraction process.
‘The beauty lies in the tailored electrolysis process, as it eliminates the individual rare earth element-oxides or halide separation and conversion steps existing in the primary mining Chinese processing route,’ explains project coordinator Ana Maria Martinez.
She points out that 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.
Martinez argues that many single extraction steps are avoided, thus making the innovative technology a much more effective and environmentally sustainable process. Besides, the ‘competitive’ 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.
Researchers report the new technology reduces energy consumption by around 35% reduction when compared to the primary production in China.
Martinez is proud of this new milestone. ‘Nobody has previously been able to demonstrate the whole permanent magnet value chain using rare earth-containing waste resources at this scale before,’ she says. ‘Our work opens up the possibility of securing an important value chain in Europe, giving a promising opportunity to rare earth recycling businesses.’
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