Uranium recovery from molten salt by reductive extraction using lithium cadmium alloy

In the pyrochemical electrorefining process of spent metal fuel, the separation of actinides and fission products is achieved based on the electrochemical stability of their chlorides. These elements could be considered to form three groups like (a) less stable noble metal fission products, (b) actinides of intermediate stability and (c) highly stable alkali, alkaline earth and rare earth fission products. During the electrorefining process, the actinide elements are selectively transported and deposited on the cathode whereas more stable fission products undergo dissolution and accumulate in the electrolyte salt. This LiCl- KCl eutectic salt used as the electrolyte is periodically treated to reduce the fission product concentrations by ion exchange using zeolite. Prior to this, the actinides present in the electrolyte salt are selectively removed by reductive extraction using Li-Cd alloy. In this study of reductive extraction, U is taken as the solute in the eutectic salt mixture under batch mode. Experiments were done in batch mode at 773 K in argon atmosphere glove box. Two runs of reductive extraction were carried out with an initial U concentration of 3.0 and 5.6 % in the salt. The percentage extraction was more than 95 % in both the runs. The order of reaction with respect to uranium concentration is estimated as 1.56 by differential method from the rate equation. (author)