Uranium stripping from tertiary amine by sulfuric acid solution and its precipitation as uranium peroxide

The uranium stripping results from a loaded tertiary amine (Alamine®336) by sulfuric acid solution and the uranium peroxide precipitation from the pregnant strip solution (PSS) are presented. The following steps were investigated: (i) uranium stripping; (ii) sulfate content reduction from the PSS and (iii) uranium peroxide precipitation. The experiments were carried out in batch as well as in continuous scale. In the stripping stage, a PSS containing 96 g/L of U3O8 was obtained, using a 4.0 mol/L H2SO4 stripping solution in six mixer-settler stages. The sulfate content reduction from the PSS was carried out by the addition of lime up to pH 3.0. After sulfate excess removal, uranium precipitation was carried out by H2O2 and MgO/Mg(OH)2 powder addition. A calcining product assaying 99.7% U3O8 was obtained.