YOKOHAMA, Japan – Nissan Motor Co., Ltd. and Waseda University today announced the start of testing in Japan of a jointly developed recycling process that efficiently recovers high purity rare earth compounds from electrified magnets in vehicle engines. The tests aim to allow the practical application of the new process by the mid-2020s.
The automotive industry promotes the electrification of vehicles to fight climate change and achieve a carbon neutral society. Most engines in electrified vehicles use neodymium magnets, which contain rare rare earth metals such as neodymium and dysprosium. Reducing the use of rare rare earths is important not only because of the environmental impact of mining and refining, but also because the changing balance of supply and demand results in price fluctuations for manufacturers and consumers.
In order to use scarce and precious resources more efficiently, Nissan has been working since 2010 from design to reduce the amount1 of heavy rare earth elements (REE) in engine magnets. In addition, Nissan recycles rare earths by removing magnets from motors that do not meet production standards and returning them to suppliers. Currently, several steps are involved, including manual disassembly and removal. Therefore, the development of a simpler and more economical process is important to achieve increased recycling in the future.
Since 2017, Nissan has collaborated with Waseda University, which has a strong track record in non-ferrous metal recycling and smelting research. In March 2020, the collaboration successfully developed a pyrometallurgy process that does not require disassembly of the engine.
1. A carburizing material and pig iron are added to the engine, which is then heated to at least 1400 C and begins to melt.
2. Iron oxide is added to oxidize the rare earths in the molten mixture.
3. A small amount of borate flux, capable of dissolving rare earth oxides even at low temperature and very efficiently recovering rare earths, is added to the molten mixture.
4. The molten mixture separates into two liquid layers, the molten oxide (slag) layer which contains the rare earths floating upward and the higher density iron-carbon (Fe-C) alloy layer s’ pushing down.
5. The rare earths are then recovered from the slag.
Tests have shown that this process can recover 98% of rare earths from engines. This method also reduces the recovery process and the working time by around 50% compared to the current method as there is no need to demagnetize the magnets, nor to remove and disassemble them.
In the future, Waseda and Nissan will continue their large-scale installation tests with the aim of developing a practical application, and Nissan will collect engines from electrified vehicles that are recycled and continue to develop its recycling system.
Nissan will continue to help build a cleaner, safer and more inclusive society as part of its efforts to develop a sustainable society. Thanks to his Nissan Green Program 2022, Nissan is tackling four priority issues: climate change, dependence on resources, air quality and water scarcity. Nissan will continue to strive for carbon neutrality and zero use of new material resources, and will simultaneously promote the use of electrified vehicles and the recycling and reduced use of rare earths.
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