Electrowinning of Neodymium Metal Using FLiNdBa Molten Salt

Abstract

Neodymium is the most used of rare earth elements. Its demand is rapidly increasing as the raw material for Nd-Fe-B permanent magnets. In the present study, the preparation of neodymium metal by molten salt electrowinning was investigated, using the support salt of LiF:NdF3:BaF2 = 7.5:67.4:25.1 (in wt%, FLiNdBa). It focused particularly on the effects of the electrowinning temperature, the cathodic current density, and the feeding rate of the raw material (Nd2O3) on the current efficiency. The current efficiency decreased almost linearly with the electrowinning temperature regardless of the cathodic current density in the temperature range (1030~1130 oC). Considering current efficiency and workability, the most suitable electrowinning temperature was 1040~1050 oC. The current efficiency increased linearly with the cathodic current density in the range of 1~4 A/cm2 irrespective of the electrowinning temperature. The effect of the feeding rate of the raw material (Nd2O3) on the current efficiency showed the same tendency as that of the cathodic current density on the current efficiency. The current efficiency of 73.6% and the metal purity of 99.8% were achieved in this study when the cathodic current density was 3.6 A/cm2 and the electrowinning temperature was 1045 oC.