Stoichiometric Relation for Extraction of Uranium from UO₂Powder using TBP Complex with HNO₃and H₂O in Supercritical CO₂

Abstract

The stoichiometry of UO2 dissolution with a tri-n-butylphosphate (TBP) complex with HNO3 and H2O was experimentally determined in supercritical carbon dioxide (SF-CO2) at 25 MPa, 323 K to estimate the required amount of the complex for a process design calculation. The molecular ratio of TBP:HNO3:H2O was determined as 1.0:1.8:0.6 when prepared as an organic phase after vigorous mixing of concentrated HNO3 and TBP. The HNO3 consumption was approximately 4 times the amount of extracted uranium. In designing a supercritical fluid extraction process, the following equation can be used to describe the overall dissolution of UO2 using the TBP complex with HNO3 and H2O in SF-CO2: