(Keynote) Separation of Dy and Nd (La) Using Molten Salt and an Alloy Diaphragm

Abstract

Cyclic voltammetry was conducted using a Ni electrode in molten LiCl-KCl-RECl3(RE=Dy, Nd) systems at 723 K. In cathodic scan, a cathodic current was observed from 1.00 V (vs. Li+/Li) due to the formation of Dy-Ni alloys in a molten LiCl-KCl-DyCl3 system. In contrast, a cathodic current was observed from 0.60 V due to the formation of Nd-Ni alloys in a molten LiCl-KCl-NdCl3 system. 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 system. The mass ratio of Dy/Nd in the alloy sample was found to be 72 by ICP-AES. Another investigation was conducted in a molten LiCl-KCl-DyCl3-LaCl3 system, with and without FeCl2 addition. Regardless of the presence of FeCl2, DyNi2 was selectively formed on a Ni plate cathode at 0.55 V.