Recovery of uranium from ammonium uranyl carbonate (AUC) effluents by combined ion exchange and membrane separation

Abstract

Ammonium uranyl carbonate (AUC) production processes have effluents with a high uranium content (5 g/L), which is conventionally recovered by evaporation. In this study, an alternative process, recovery of uranium by strong anion exchange (AE) membranes is investigated. Solutions were modeled by MINTEQA2 for determining the species present. Laboratory scale AUC precipitations with three different C/U mole ratios were carried out using uranyl nitrate (UNH) feed solution from the pilot plant for the purpose of determining the remaining concentration of uranium in the effluents. Strongly basic AE membrane separations of these effluents were carried out, but separation was not effective because of the limited surface area of the membranes. Synthetic solutions of three different C/U mole ratios were prepared and passed through a column of strongly basic AE resin. Membrane separations were then carried out on the resulting Solutions. Membrane separations proved to be effective only in dilute solutions of uranium. There was a complementarity between the AE resins and membranes for U(VI) recovery from carbonate solutions in that different uranyl carbonate anionic species were extracted to differing extents with the two procedures.