Feasibility studies on electrochemical recovery of uranium from solid wastes contaminated with uranium using 1-butyl-3-methylimidazorium chloride as an electrolyte

•The uranium component of steel wastes and spent NaF adsorbent are easily dissolved into BMICl.•The uranyl(VI) species in BMICl are reduced to U(V) irreversibly around −0.8 to −1.3V.•The dissolved uranium species in BMICl are recovered as black deposits electrolytically.•The deposit is the mixtures of U(IV) and U(VI) compounds containing O, F, Cl, and N elements.