An integrated process for the removal of Cd and U from wet phosphoric acid

In this work, an integrated process based on the application of two membrane technologies for the selective recovery of the U and the Cd contained in wet phosphoric acid is presented. The process is based on the removal of U by ion exchange using the Purolite S940 resin as ion-exchange resin followed by the selective removal of Cd by means of membrane-assisted solvent extraction with Aliquat 336 as the selective extractant. After sorption of U, the elution step was carried out with a 1 M solution of Na2CO3 whereas the back extraction of Cd was efficiently achieved by simply using water in the back-extraction phase. Because of working with acidic solutions containing initially 200 mg/L of U and 50 mg/L of Cd, the viability of the process for reduction of the U and Cd concentration below 2 mg/L has been checked, obtaining the kinetic models and parameters of the removal steps, thus, establishing the basis for the process design and optimization.