Process for uranium recovery using Cyanex 272

Abstract

The extraction of uranium and iron (III) from mixed sulfate/chloride media with Cyanex 272 was studied, and a mechanism proposed involving cation exchange of UO22+ and Fe(OH)2+. Cyanex 272 exhibited good selectivity for uranium over iron (III), with βU/Fe=129 at pH1. An antagonistic effect was observed with the addition of Alamine 336 to Cyanex 272, causing a decrease in the extraction of iron (III). In contrast, synergism was observed for the extraction of uranium with the Cyanex 272/Alamine 336 combination. Based on the results obtained, a new chloride tolerant process for uranium recovery from acidic sulfate liquors is proposed, based on Cyanex 272 alone. McCabe–Thiele analysis of the uranium extraction isotherm for 0.1M Cyanex 272 showed 99% uranium extraction with 3 equilibrium stages, from a sulfate feed liquor containing 1g/L U, 2g/L Fe(III), and 20g/L Cl at pH1.75. High uranium loadings were achieved (9g/L U), with 0.2g/L Fe co-extracted. Sulfuric acid stripping with 4M H2SO4 was effective, with the McCabe–Thiele diagram indicating that a 5 stage strip circuit would produce a loaded strip containing approximately 45g/L U.