By Leibniz Institute for Solid State and Materials Research Dresden - IFW Dresden
Rare earths (RE) elements like Nd, Pr, Dy, Tb are key constituents of modern permanent magnets but, considering their perspective availability they are considered as most critical materials. Recycling of RE from Nd-Fe-B-magnet scrap is one strategy to oppose this problem. Melt-metallurgical processing under utilization of phase separation phenomena based on the immiscibility of involved elements is a way to accumulate RE in one phase. We proposed an approach in which Cu is used as agent for phase separation upon melting and solidification. Above a critical Cu content in a mixture with NdFeB scrap large phase separation into (Nd,Cu)-rich and (Fe,B)-rich regions was observed. Nd recovery from (Cu,Nd)-rich fractions is possible by various approaches exploiting the large chemical property differences between the reactive rare earths elements and the noble Cu.
