Electrowinning of Neodymium Metal Using FLiNdBa Molten Salt

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.