A. Karati, H. Parmar, T. Riedemann, M. Besser, D. Prodius, I.C. Nlebedim
Ames National Laboratory,
United States
Keywords: rare earth metals, rare earth fluoride, metallothermic, hydrogen fluoride, sodium neodymium fluoride, rare earth metallization, rare earth reduction
Summary:
We will present the successful production of rare earth (RE) metal using Na-RE-F. Presently, RE metals are preferably produced using RE-fluoride due to its higher air and moisture stability compared to RE-chloride. However, its preparation requires the use of corrosive and hazardous chemicals such as hydrofluoric acid (HF) or ammonium bifluoride (NH4HF). The presentation will show, for the first time, that Na-RE-F is an alternative salt to the typically used RE-fluoride. The Na-RE-F for this work was produced via a scalable hydrometallurgical approach using three different RE salts as feedstock, including acetate, nitrate, and chloride. HF was neither used nor generated during the salt preparation process. Furthermore, the Na-RE-F powder was dried in air (without dry HF) and only water evolved during the drying process. Analyses of the Na-RE-F show that NaF is liberated as a flux during the heating process, which lowers the salt reduction temperature to <900 °C, thus minimizing or eliminating the need for additional flux. Calciothermic reduction of the Na-RE-F salt was successfully employed to obtain RE metal. This work represents a safer, greener, and more widely deployable approach for producing the RE metals needed for permanent magnets that will support the transition to a cleaner society via the decarbonization of the transportation industry.