Worldwide demand for permanent magnets is
on the rise, putting pressure on supplies of the rare-earth minerals—like neodymium
and dysprosium—they contain. End-of-life recycling could reduce manufacturers’
dependence on China for these strategic raw materials. Researchers at Liten
recently succeeded in producing magnets containing up to 25% recycled material
that perform as well as those currently on the market.
The researchers used a
dry recycling technique, grinding the used magnets (or magnet manufacturing
waste) and re-injecting the resulting powder into the standard manufacturing process.
They then improved the grinding parameters to obtain a homogeneous powder
(5-micron grains on average) that they mixed in different proportions with new
powder under controlled conditions to protect from oxidation. With 25% recycled
powder they achieved complete densification after sintering and magnetic
properties almost equivalent to a magnet manufactured with new powder alone
(less than 3% loss).
Researchers are now working
to increase the proportion of recycled powder. A strip casting furnace will go
online at CEA Grenoble in September 2015, allowing the researchers to also test
fusion recycling techniques.