Permanent Magnet Recycling

Rare earth permanent magnets are an integral part of many electrical and electronic devices as well as numerous other applications, including emerging technologies like wind power, electric vehicles, fully automized industrial machines, and robots. EEE (Waste Electrical and Electronic Equipment) has become the fastest growing waste stream in Europe [1].

Scrap rare earth permanent magnets from various sources and applications can be collected and processed for recycling using hydrogen decrepitation (HD) and hydrogenation disproportionation desorption and recombination (HDDR) processes [2].

The magnetic properties of recycled magnets made of regained scrap magnet powders come close to those made of primary materials. In the cases of the sintered magnets and hot-deformed magnets that contain various amounts of scrap powders, both remanence and coercivity systematically score slightly lower than those of magnets made from virgin materials. In the case of sintered magnets that are fully recycled and doped with 2 wt% NdH2, magnetic properties decrease by only a few percent. This approach seems to be the most promising.

[1] O. Diehl, M. Schönfeldt, E. Brouwer, A. Dirks, K. Rachut, J. Gassmann, K. Güth, A. Buckow, R. Gauß, R. Stauber, O. Gutfleisch, Towards an alloy recycling of Nd-Fe-B permanent magnets in a circular economy, Journal of Sustainable Metallurgy (2018) 1-13;
DOI: 10.1007/s40831-018-0171-7

[2] A. Lixandru, I. Poenaru, K. Güth, R. Gauß, O. Gutfleisch, A systematic study of HDDR processing conditions for the recycling of end-of-life Nd-Fe-B magnets, J. of Alloys and Compounds 724 (2017) 51-61.
DOI: 10.1016/j.jallcom.2017.06.319

[3] A. Lixandru, P. Venkatesan, C. Jönsson, I. Poenaru, B. Hall, Y. Yang, A. Walton, K. Güth, R. Gauß, O. Gutfleisch, Identification and recovery of rare-earth permanent magnets from waste electrical and electronic equipment, Waste Management 68 (2017) 482-489.
DOI: 10.1016/j.wasman.2017.07.028