Annual report for Ion Replacement Program

Ion replacement electrorefining is an innovative electrochemical approach to purifying and separating metals. This approach overcomes the shortcomings of conventional electrorefining and has the potential for processing a wider range of metals and metal halide salts. Salt waste is also minimized with this approach. The key element of ion replacement electrorefining is the ion replacement electrode. This electrode allows a decoupling of the electrotransport process into two separate steps, anodic dissolution and cathodic deposition. Three key accomplishments described in this report that demonstrate the feasibility of ion replacement electrorefining are: (1) we have identified a suitable sodium/β double-prime-alumina/molten salt electrolyte system that functions reproducibly at 723 K, (2) we have oxidized and deposited dysprosium, lanthanum, uranium, and titanium by using a sodium ion replacement electrode. In several experiments, an actual separation of dysprosium and lanthanum was observed, and (3) we have identified a metal alloy, LixSb, as an alternative ion replacement electrode. The next stage in the program is the design, construction, and testing of a laboratory-scale electrorefiner. Follow-on development with funding from industrial and federal sponsors is being pursued