A study on the development of fluorination process

As the high temperature electrorefining is carried out in the electrolyte medium of molten salt such as metal halide eutectic mixture, metal chlorides or metal fluorides should be prepared before the electrochemical operation. In this study, therefore, fluorination of various metals and metal oxides were studied. Two types of fluorination methods, that is, fluorination in molten salt and fluorination by gas-solid reaction were compared. It was found that the latter method was more effective for the fluorination of Zr, CeO2, Nd2O3, and SrO. Noble metals, however, did not react with hydrogen fluoride and thus could be separated from other elements. In parallel with this, various reaction models were compared with the experimental results. As result, the phase boundary controlled-model was found to be suitable for CeO2, whereas the nucleation and growth-model showed a good simulation for Nd2O3 and SrO. (author)