Purification of gadolinium by electrorefining

The electropurification of crude gadolinium, as an alternate method to the distillation process currently used, was studied using a LiCl−LiF−GdF₃ electrolyte. The best results were obtained with a 77.6 wt pct LiCl, 11.2 wt pct LiF, 11.2 wt pct GdF₃ electrolyte at 700°C. It was shown that the purity of the deposit was strongly dependent on the purity of the electrolyte and the temperature. The purest deposit of Gd was obtained when the LiCl and LiF were purified by distillation and high purity GdF₃ was used. The analyses LiCl and LiF were purified by distillation and high purity GdF₃ was used. The analyses showed this purest gadolinium is still less pure than the gadolinium prepared by the distillation process. The effect of various methods used to remove the adhering electrolyte salts and to consolidate the deposited dendrites was studied. Removal of the adhering salts by distillation followed by arc and electron beam melting of the dendrites gave the purest Gd. The analyses of the metal prepared under the various conditions are given. HIROSHI NAGAI, formerly a Post-Doctoral Associate, Ames Laboratory-DOE. Iowa State University, Ames IA 50011.