CONCENTRATION OF URANYL SULFATE-SOLUTION BY AN EMULSION-TYPE LIQUID MEMBRANE PROCESS

The applicability of the emulsion-type liquid membrane process using tri-n-octylamine (TNOA) as an extractant to concentrate uranium from sulfuric acid solutions was investigated. It was found that this liquid membrane process yields much higher extraction percentages than the conventional solvent extraction process using the same amount of TNOA. The liquid membrane process is particularly suitable for dilute solutions such as leach and wash solutions of uranium ores. Effects of various factors on the stability of emulsions and the extraction rate and percent extraction of U (VI) were examined. Among various agents tested, Na2CO3 was found to be preferable to strip sulfato-complexes of U (VI) in the internal phase. Batch-type extractions of U (VI) by the emulsion-type liquid membrane method were performed to simulate a two-stage counter current extraction, and the experimental results suggest that the U (VI) concentration in the final raffinate can be lowered to below 1 g m-3 when the feed solution containing 1 kg m-3 U (VI) is treated by a two-stage extraction.