Electrochemical extraction of uranium from U3O8 by preparing flower-shaped Al-U intermetallics in LiCl-KCl-AlCl3 melts

This work presents the electrochemical behavior of U3O8 and the formation of Al-U intermetallics in LiCl-KCl-AlCl3 melts at 813 K by various electrochemical test methods. The signals of three intermetallics attributed to Al2U, Al3U and Al4U were detected in the electrochemical curves. The standard Gibbs free energy of formation of Al-U intermetallics, the partial molar Gibbs free energies and activity of U in two phase coexisting states were calculated based on the open circuit chronopotentiometry at 813 and 843 K. U was extracted from U3O8 by forming Al-U intermetallics on Al sheet via potentiostatic electrolysis at -2.0 V in LiCl-KCl-AlCl3-U3O8 molten salt. The X-ray diffraction (XRD) indicated that Al4U, Al3U and Al2U phases were formed. The densely arranged flower-shaped Al-U intermetallics were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS). In addition, the extraction efficiency of U(IV) was 92.3% after potentiostatic electrolysis at -2.0 V for 10 h.