Process for uranium recovery using Cyanex 272

• Proposed uranium process that is effective in mixed sulfate/chloride media
• Cyanex 272 is used to extract uranium selectively over iron (III).
• The solvent can be effectively stripped with 4 M sulfuric acid.
• Mixed Cyanex 272/Alamine 336 reagent tested but found to suppress uranium stripping
• The proposed process does not produce ammonium sulfate waste effluent.

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 pH 1. 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 0.1 M Cyanex 272 showed 99% uranium extraction with 3 equilibrium stages, from a sulfate feed liquor containing 1 g/L U, 2 g/L Fe(III), and 20 g/L Cl at pH 1.75. High uranium loadings were achieved (9 g/L U), with 0.2 g/L Fe co-extracted. Sulfuric acid stripping with 4 M H2SO4 was effective, with the McCabe–Thiele diagram indicating that a 5 stage strip circuit would produce a loaded strip containing approximately 45 g/L U.

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