24 April 2018
The US Department of Energy's Critical Materials Institute (CMI) has developed a new recycling process to turn discarded hard disk drive (HDD) magnets into new magnet material in a few steps, in an attempt to address both the economic and environmental issues associated with mining e-waste for valuable materials.
Plasma torch depositing recycled magnet material. Image: US Department of Energy, Ames Laboratory
‘There are a lot of ways to go about getting the rare-earth elements out of e-waste, and some of them are very effective, but some create unwanted by-products and the recovered elements still need to be incorporated into a new application,’ said Ryan Ott, a member of the CMI research team and scientist at the DOE’s Ames Laboratory. ‘Here we have eliminated as many processing steps as we can, and go straight from the discarded magnet to an end product, which is a new magnet.’
Scrapped HDD magnets – which have a relatively centralised scrap source in the US – are collected, then stripped of protective coatings. They are then crushed into powder, which is then deposited on a substrate using plasma spray to synthesize coatings 0.5-1mm thick, with processing controls influencing the properties of the end product.
The resulting material cannot retain the exceptional magnetic properties of the original, but it could fill the market need for an economical material where the magnetism of a high-strength rare-earth magnet is not required, but lower performing magnets like ferrites are insufficient. The process could also be used to produce strong magnets for small-scale applications, such as hand-held electronics.
‘This waste reduction aspect of this process is really two-fold; we're not only reusing end-of-life magnets, we are also reducing the amount of manufacturing waste produced in making thin and small-geometry magnets out of larger bulk materials,’ Ott said.