Recycling magnets is worthwhile

News 2019-02-13 at 10:23
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A pilot carried out in the Circwaste project yielded promising results on the manufacturing of recycled magnets. The recycling of magnets has great potential to grow into a profitable business for recycling companies.

Sintered magnets are important building blocks in modern electricity generation and energy-efficient motors. Magnets contain rare-earth metals, such as neodymium and dysprosium, the production of which is currently almost fully concentrated in China. Western countries have started researching and developing methods for recovering these rare-earth metals from used magnets and reusing them.

‘In order for a magnet made from recycled raw materials to honestly be called a recycled magnet, recycled raw material should account for at least half of the raw material used. However, the higher the percentage of recycled raw material, the more challenging the magnet’s manufacturing becomes,’ Project Manager Minna Haavisto from Prizztech Oy says.

At present, most magnets are recycled among waste iron, which means that only the iron contained in the magnets is recovered. The rare-earth metals mostly end up as impurities in the recycled iron. However, the most energy-efficient method of recycling magnets is to crush discarded magnets, pulverise them and mix them with virgin raw material.

Recycling holds great potential in the manufacturing of magnets

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The magnet recycling pilot of the Circwaste project tested the disassembly of a discarded permanent magnet rotor and recycling of magnets into raw material for new magnets by pulverising them.

Two industrial-scale batches of recycled magnets (300 kg each) were manufactured in the project, with one batch containing 50 per cent recycled raw material and the second 75 per cent. Small proportions of these batches were mixed together, making it possible to test a third recycled raw material content.

The scrap magnets proved to be relatively easy to remove from the rotor after thermal treatment. The magnets were also successfully cleaned and the nickel coating was removed without any impurities that would weaken the material’s properties ending up in the recycled, crushed raw material.

‘The magnet manufacturing process is very challenging, and the handling of a new type of recycled material requires the production process to be fine-tuned. However, the properties of the best recycled magnets manufactured in the pilot were almost at the level of original magnets. We succeeded in demonstrating that recycling has potential in the manufacturing of magnets,’ Haavisto says.

Recycling of magnets into profitable business

The collection and separation of scrap magnets is a potential new business area for recycling companies.

‘The solid professional skill of Neorem Magnets Oy in the manufacturing of magnets contributed greatly to the pilot’s success,’ Haavisto says. ‘Neorem is also interested in developing types of recycled magnets and adding them to its product range. However, this would require adequate amounts of scrap magnets of uniform quality. Recycling implemented with pulverisation is also likely profitable with large batches of scrap magnets. The price of recycled raw material has, at least for the time being, been clearly more affordable than that of virgin material.’

Recycling magnets with the pulverisation method also saves considerable amounts of energy compared to the traditional production of raw material that starts from mines. According to one calculation, the pulverisation method delivers as much as 90 per cent energy savings compared to the traditional method of manufacturing magnets.

The results achieved in the Circwaste project provide a good basis for follow-up projects carried out in order to identify potential ways to automate the recovery of magnets and test the removal of magnets from a wind turbine and the engine of an electric vehicle. Follow-up projects will also be carried out to prepare instructions for designers of engines and turbines on how disassembly and the recyclability of magnets could be taken into consideration better in the design of the devices.
 

More information

Project Manager Minna Haavisto, Prizztech Oy,
firstname.lastname@prizz.fi