Development of innovation industrial technologies is inseparably connected with modernization of methods of manufacturing high-technology products. One example of such products is metallic neodymium that is in a high demand in the world market. Currently there are increasing demands for neodymium due to its enhanced consumption in production of high-energy magnets, batteries and superalloys. Electrolysis of molten salts is one of the possible methods of neodymium production. Mixed chloride-fluoride electrolytes are the most prospective media for neodymium production in terms of their physico-chemical properties and organization of the process. Detailed information concerning the mechanisms and kinetics of the electrode reactions in such media is required to enhance the technological parameters of the process. In the current work the electrochemical behavior of neodymium was studied in LiCl-NdF3 and CaCl2-NdF3 melts in a wide temperature range (from 750 to 1050 0С). Neodymium concentration was varied from 4 to 20 wt. % NdF3. The investigation was carried out using stationary (chronopotentiometry) and non-stationary (cyclic and square-wave voltammetry) techniques. The methods of galvanostatic and potentiostatic electrolysis were applied in a special series of experiments. It was found that electroreduction of neodymium in all studied melts proceeds in a single three-electron step. Electrokinetic parameters of neodymium reduction at different temperatures and Nd(III) concentrations were estimated. The limiting current densities were determined. They predictably increase with increasing temperature and concentration of neodymium in the melt. It is shown that increase of polarizing current density above the limiting value leads to the secondary reduction of neodymium by alkali and alkaline-earth metals formed on the cathode. Increasing temperature results in increase of physical solubility of neodymium in the studied electrolytes. High solubility of neodymium in the melt causes noticeable decrease of current efficiently during electrolytic production of neodymium. It was found that metallic neodymium is formed in the liquid state when the electrolytic reduction was performed at 1050 0C. Solubility of the liquid metal in the molten electrolytes was estimated under the experimental conditions. It was confirmed that the electrolytic reduction of neodymium at high temperatures simplifies separation of the metal from quenched electrolyte.

Electrochemistry of neodymium in chloride-fluoride melts

249th National Meeting (2015)

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