Recycling of end-of-life Nd-Fe-B magnets is an important strategy for reducing the environmental dangers associated with rare-earth mining and overcoming the supply risks associated with the rare-earth elements. In this study, a novel concept for recycling of sintered Nd-Fe-B magnets by directly recovering the matrix Nd2 Fe14 B grains is presented. The procedure is based on the anodic etching of sintered Nd-Fe-B magnets in a nonaqueous dimethylformamide (DMF)/0.3 mol L-1 FeCl2 bath. Selective recovery of Nd2 Fe14 B grains was realized within the applied current density <5 mA cm-2 based on the etching priority of phases: metallic Nd > intergranular NdFe4 B4 > matrix Nd2 Fe14 B. The total energy consumption of the proposed recycling route is estimated to be 2.99 kWh kg-1 , which is comparable to the state-of-the-art methods. However, the proposed recycling route is currently the only procedure that enables repeated recycling of sintered Nd-Fe-B magnets in a closed-loop system.
Keywords: electrochemistry; etching; extraction; magnets; rare-earth elements.
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