Studies on the separation of dissolved uranium from alkaline carbonate leach slurries by resin-in-pulp process

The increasing demand for uranium fuel for energy generation has triggered interest in the exploitation of various resources including lean tenor ores and tailing dumps which are otherwise considered uneconomical till recently. The process-schemes of new plants are incorporating several new technologies such that the process is economically attractive and eco-friendly. One such development catching the lime-light in uranium ore processing industry everywhere is the resin-in-pulp (RIP) technology. This paper describes the results of laboratory studies on the recovery of dissolved uranium values from an alkaline leach slurry of a medium-grade uranium ore from Gogi (Karnataka, India) using the resin-in-pulp (RIP) process. Besides anionic carbonate complex of uranium – [UO2(CO3)3]4−, the other major anionic constituents of the leach solution are CO32-, HCO3−, SO42-, Cl−, PO43- and MoO42-. The total dissolved solutes (TDSs) are about 45 g/l. Various commercially available strong base anionic type resin-in-pulp (RIP) grade resins – both macro-porous and gel type, were studied with respect to their loading capacity. The gel type polystyrene based resins grafted with quaternary ammonium ion gave superior loading capacity in comparison to macro-porous resins. Parametric variation studies for optimizing the other process conditions, including adsorption kinetics, were then carried out on the short-listed resin. Results of the semi-continuous counter-current extraction and elution tests indicated that about 98% of the dissolved uranium values can be recovered during the loading process and practically the entire loaded uranium can be eluted using NaCl eluant.

• RIP studies were carried out on U bearing alkaline leach slurry with d50 of 34 μm.
• Gel type gave superior loading capacity in comparison to macro-porous resins.
• 98% of the U values could be separated out from leach solution containing 700 mg/l of uranium with TDS of 40 g/l.
• A loading capacity of 65–70 g/l of wet settled resin was achieved.
• The sorption process follows pseudo-second order kinetics.