Estimation of Uranium(VI) Concentrations by Temperature Profile in Solvent Extraction Processes Using 30% Tri-n-Butyl Phosphate Diluted with n-Dodecane.

Abstract

In the counter-current solvent extraction process where 30% tri-n-butyl phosphate (TBP) diluted with n-dodecane is used to extract U(VI), the reaction heat that primarily results from complex formation of TBP with U(VI) causes a heat release near the extraction band where U(VI) is transferred from aqueous to organic phase. This study has shown that the U(VI) concentration profile can be estimated based on a temperature profile by taking account of mass and heat balances in the counter-current solvent extraction process. A computer program UCE has been developed to estimate U(VI) concentrations in mixersettler type extractors by giving a temperature profile and process data of the feed streams as input data. This computer program numerically solves the equations derived from material and heat balances in the solvent extraction process without using distribution ratios. Feasibility of UCE as a tool to detect U(VI) concentration change is discussed by the comparison with the calculation results which are given by the computer program SOLE-91 that calculates profiles of U(VI) concentration and temperature. Since the U(VI) concentration profiles estimated by UCE for hypothetical process upsets agree with the profiles given by SOLE-91, it is concluded that the detection of the position of the U(VI) extraction band is feasible.