Solvent extraction of uranium

Pai, S. A. Lohithakshan, K. V. Mithapara, P. D. Aggarwal, S. K. Solvent extraction of uranium(VI) plutonium(VI) and americium(III) with HTTA/HPMBP using mono-and bi-functional neutral donors Synergismand thermodynamics. J. Radioanal. Nucl. Chem. 2000, 245, 623-628. 

AMEX [Amine extraction] A process for the solvent extraction of uranium from sulfuric acid solutions using an amine extractant ... 

Dapex [Di-alkylphosphoric acid extraction] A process for the solvent extraction of uranium from sulfuric acid solutions using di-(2-ethylhexyl) phosphoric acid (HDEHP). The HDEHP is dissolved in kerosene containing 4 percent of tributyl phosphate. The uranium is stripped from the organic phase by aqueous sodium carbonate and precipitated as uranyl peroxide (yellow cake). The process was no longer in use in 1988. See also Amex. 

As noted earlier (see section 12.3.1), the Amex process, which uses long-chain amines, is preferred over the Dapex process, which uses HDEHP, for solvent extraction of uranium from H2SO4 leach solutions. Because the surfactant properties of amine sulfates are conducive to formation of objectionable emulsions, the Amex process is very sensitive to the presence of solids in the H2SO4 leachate. For acceptable phase coalescence in the Amex process, feeds should contain no more than 20 ppm solids. The Dapex process can tolerate feeds containing as much as 100 ppm solids. 

Preston, J.S., du Preez, A.C. 1999. The influence of extractant structure on the solvent extraction of uranium(VI) and thorium(IV) from nitrate media by dialkyl sulphoxides. J. Chem. Technol. Biotechnol. 69 (1) 86-92. 

Blake, C.A. Jr. Baes, C.F. Jr. Brown, K.B. Coleman, C.F. White, J.C. Solvent extraction of uranium and other metals by acidic and neutral organophosphorus compounds, In Peaceful Uses of Atomic Energy. Vol. 28, Basic Chemistry in Nuclear Energy, United Nations, Geneva (1958), pp. 289-298. 

B. Separation of Uranium from Thorium by Solvent Extraction of Uranium... 

The early experiments on solvent extraction directly from leached pulp were beset with problems such as losses of solvent in the aqueous phase and the formation of emulsions. The use of mixer-settler, pump mixer, and internal mixer-settler type contactors on a laboratory scale (Gil) has demonstrated the feasibility of uranium extraction from desanded slurries with 5-1. )% solids and from high-density slurries with 48-60% percent solids. The deemulsification rate of a synthetic slurry as a function of the temperature of the system and the pH of the slurries (T12) and the effect of extractant entrainment in the aqueous effluent on solvent extraction of uranium from slurries containing more than 40% solids (E6) have been studied. 

We have used tri-n-octylphosphine oxide (TOPO) as a solvent extractant of uranium(VI) and thorium(IV) from nitric and hydrochloric acid solutions (1-3). In contrast, the extraction of uranium(VI) and thorium(IV) from nitric and hydrochloric acid solutions has been investigated by tri-n-butylphosphate (TBP) (4, 5). However, since TBP reveals a poor efficiency for the extraction of metals from sulphuric acid solutions, this paper extends the work to the extraction of uranium(VI) from sulphuric acid solutions by TOPO. 

Ihree papers from Oak Ridge National Laboratory provide a comprehensive summary of developments in solvent extraction of uranium firom leach liquors. Coleman et al. [C2] describe studies of a number of possible amine extractants. Blake et al. [B4] describe work with organophosphorus compounds. Brown et al. [B8] describe processes based on both types of extractants. 

Elus, D. a. et al. Entrainment studies on solvent extraction of uranium from heavy slurries. Proc 2nd. Int. Conf. on the Peaceful Uses of Atomic Energy, Geneva, 1958. Paper 497. 

Kumar, J.R., Kim, J.-S., Lee, J.-Y. Yoon, H.-S. (2011) A brief review on solvent extraction of uranium from acidic solutions. Separation Purification Reviews, 40, 77-125. 

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