Electrochemical separation of Dy from Nd magnet scraps in molten LiCl–KCl

Abstract

We proposed a new separation and recovery process for RE metals from Nd magnet scraps using molten salt electrolysis. The present study focused on the electrochemical formation of RE–Ni (RE = Dy, Nd, Pr) alloys in a molten LiCl–KCl system at 723 K. Cyclic voltammetry was conducted using a Ni electrode in molten LiCl–KCl–RECl3 systems at 723 K. In the negative scan for the DyCl3 added system, a large cathodic current was observed from 0.70 V (vs. Li+/Li) as a result of the formation of Dy–Ni alloys. In contrast, large cathodic currents as results of the formation of Nd–Ni and Pr–Ni alloys were observed from 0.60 V. On the basis of these results, an alloy sample was prepared by potentiostatic electrolysis at 0.65 V for 1 h using a Ni plate cathode in a molten LiCl–KCl–DyCl3–NdCl3–PrCl3 system. The mass ratio of Dy/Nd+Pr in the alloy sample was found to be 50 by ICP-AES. Finally, a Dy permeation experiment was conducted with a new electrolytic cell.