Preliminary Study on Separation of Dy and Nd by Multi-Step Extraction Using TDdDGA

Mutual separation technique of Dy and Nd in Nd magnets is studied. Dy is more valuable than Nd, and therefore, Dy should be isolated and reused. Lanthanide elements can be extracted thoroughly by using diglycolamide (DGA) extractants, and we use this reagent to recover and isolate Dy. N,N,N',N'-Tetradodecyl-DGA (TDdDGA) has a relatively high separation factor (SF) between Dy and Nd (SF: over 10) in the HNO3 extraction system, so multi-step extraction using TDdDGA is applied to mutually separate them. In the present study, by using the condition, four extraction steps, organic phase: 0.1 M TDdDGA in n-dodecane, aqueous phase: 0.3 M HNO3, 92 % Dy can be recovered with 0.7 % co-extraction of Nd.