Recovery of uranium and thorium from secondary resources

In the present paper an effort has been made to briefly describe first the effort that has been made at Rare Earths Division (RED), Alwaye, and Orissa Sands Complex (OSCOM) of IREL to recover nuclear grade ADU from uranium bearing monazite (0.35% U3O8) and other sources like thorium hydroxide (0.6% U3O8) and uranium fluoride concentrate (40%U). All these processes developed have similarity in the sense that they involve solvent extraction technology with novel combination of three different reagents falling in the category of acidic (PC88A) basic (ALAMINE-336) and neutral (TBP) extractants. Extensive R and D work in collaboration with uranium extraction division of BARC and plant scale trials have been completed to standardize the processes with respect to choice of ligands, composition of extractants, scrubbing/stripping reagents, number of stages as well as organic to aqueous ratios. Tons of ADU meeting the stringent specification have been produced and supplied to BARC for making uranium metal fuel for research reactors of the centre. In the case of uranium recovery from dilute phosphoric acid, the present paper is confined to use of a synergistic combination of DEHPA and TBP rather than well proven DEHPA-TOPO mixture. The primary motivation for examining this synergistic combination is the indigenous availability of both the solvent components since the supply of TOPO from the international market is likely to be denied. Based on the results of R and D test carried out at BARC large scale trials of various dilute phosphoric acids using experimental rigs consisting of carbon column, heat exchanger, commercial sized single stage mixer-settler, and plate separator are in progress at RED and OSCOM. IREL is also at advanced stage of pre-project activities and commercial negotiation with a number of host fertiliser companies like PPL, FACT and SPIC generating and using large volume of uranium bearing dilute phosphoric acid