Comparative study of monolithic platinum and iridium as oxygen-evolving anodes during the electrolytic reduction of uranium oxide in a molten LiCl–Li2O electrolyte
A series of four electrolytic reduction runs was performed in molten salt at bench scale to compare the performance characteristics of monolithic platinum and iridium as oxygen-evolving anodes, while simultaneously reducing uranium oxide to metal. In each run, 25 g of uranium oxide particulate was loaded into a permeable steel basket, which, in turn, was immersed in a pool of LiCl—1 wt% Li2O at 650 °C. Both anodes, each 3 mm in diameter, were suspended vertically in the salt pool, adjacent to the steel cathode basket. The anodes were connected in parallel to separate direct current power supplies with the uranium oxide-loaded basket as the common cathode. A cell voltage (3.1 V) was intermittently applied to the system with both power supplies operating concurrently, effecting the reduction of uranium oxide to uranium metal at the cathode basket and the simultaneous oxidation of oxygen anions in the salt to oxygen gas at each anode. Anode and cathode potentials and currents were recorded to compare the performance of platinum vis-à-vis iridium. After completing the series of runs, both anodes were removed and subjected to dimensional, chemical, and microscopic analyses. Even though the accumulated charges on each anode over the series of four runs were similar, the platinum anode exhibited up to 29% reduction in cross-sectional area compared to < 3% for the iridium anode.
KeywordsElectrolytic reduction Oxide reduction Uranium oxide Platinum anode Iridium anode Lithium chloride–lithium oxide electrolyte
This work was supported by the U.S. Department of Energy (DOE), Office of Nuclear Energy, under DOE Idaho Operations Office contract DE-AC07-05ID14517.
- 1.Gourishankar K, Redey L, Williamson M (2002) Electrolytic Reduction of Metal Oxides in Molten Salts. In: Schneider W (ed) Light metals 2002. The Minerals, Metals and Materials Society, Pennsylvania, pp 1075–1082Google Scholar
- 10.Herrmann SD, Li SX, Westphal BR (2012) Separation and recovery of uranium and group actinide products from irradiated fast reactor MOX fuel via electrolytic reduction and electrorefining. Sep Sci Technol 47:2044–2059Google Scholar
- 14.Outotec (2015) HSC chemistry 8. Outotec, PoriGoogle Scholar
- 15.ASM International (2016) ASM alloy phase diagram database. Villars P (ed) https://matdata.asminternational.org/apd/index.aspx
- 21.Modic KA, Smidt TE, Kimchi I, Breznay NP, Biffin A, Choi S, Johnson RD, Coldea R, Watkins-Curry P, McCandless GT, Chan JY, Gandara F, Islam Z, Vishwanath A, Shekhter A, McDonald RD, Analytis JG (2014) Realization of a three-dimensional spin-anisotropic harmonic honeycomb iridate. Nat Commun 5:4203. https://doi.org/10.1038/ncomms5203 CrossRefGoogle Scholar