Coulometric determination of uranium in perchloric acid medium and its applications

A controlled potential coulometric method has been developed in 1M HClO4 for the determination of uranium using an electrolysis cell and coulometer. A noteworthy feature of this method is its applicability even in the presence of large excess of calcium, barium and lead in situations where the commonly used coulometric method in 0.5M H2SO4 medium and the well known potentiometric method in H3PO4 medium are not applicable. Results of the determination of uranium in a number of aliquots of synthetic solutions of (U,Ca), (U,Ba) and (U,Pb) showed a precision of the order of 0.2% and the experimental values of uranium content agreed with the expected values within the precision limits. Similar results were obtained with samples of synthetic mixtures of U3O8 and CaF2 powder containing 1-5% U and 95-99% Ca. The method was then successfully used to determine the U content of some typical samples of CaF2 slag (containing 1-5% U) generated during the calciothermic reduction of UF4 to U-metal at conversion plants. (author)