Uranium from wet-process phosphoric acid

The O or S atoms in P=0 and P=S groups may act as electron donors although these groups form relatively weak complexes with electron acceptor compounds such as nonpolarizable, more electropositive (ie, hard) acids, including protons (14). Use is made of this property in the recovery of uranium from wet-process phosphoric acid by extractants such as trioctylphosphine oxide [78-50-2] and di(2-ethylhexyl) hydrogen phosphate [298-07-7]. 

DEPA-TOPO [di (2-ethylhexyl) phosphoric acid and trioctylphosphine oxide] A process for recovering uranium from wet-process phosphoric acid, by solvent extraction with a mixture of the two named reagents. Developed at Oak Ridge National Laboratory and first commercialized in 1978 by Freeport Minerals Corporation and Wyoming Mineral Corporation. 

Hurst, F. J. Recovery of uranium from wet-process phosphoric acid by solvent extraction, presented at Annual AIME Meeting, Las Vegas, February 1976. Young, W. Davy Power-Gas, Paper at AIME Annal Meeting, New Orleans, February 1979, p. 59. 

Fundamental studies have been reported using the cationic liquid ion exchanger di(2-ethylhexyl) phosphoric acid in the extraction of uranium from wet-process phosphoric acid (H34), yttrium from nitric acid solution (Hll), nickel and zinc from a waste phsophate solution (P9), samarium, neodymium, and cerium from their chloride solutions (12), aluminum, cobalt, chromium, copper, iron, nickel, molybdenum, selenium, thorium, titanium, yttrium, and zinc (Lll), and in the formation of iron and rare earth di(2-ethylhexyl) phosphoric acid polymers (H12). Other cationic liquid ion exchangers that have been used include naphthenic acid, an inexpensive carboxylic acid to separate copper from nickel (F4), di-alkyl phosphate to recover vanadium from carnotite type uranium ores (M42), and tributyl phosphate to separate rare earths (B24). 

Hayworth HC, Ho WS, Bums WA, and Li NN. Extraction of uranium from wet process phosphoric acid by liquid membranes. Sep Sci Technol 1983 18 493-521. 

Hurst, F.J. and Crouse, D.J., Recovery of uranium from wet-process phosphoric acid by extraction with octylphenylphosphoric acid. Ind. Eng. Chem. Proc. Des. Dev., 1974, 13 286-291. 

Hayworth, H.C., Advantages of hquid membrane technology for the extraction of uranium from wet process phosphoric acid. 2nd Chemical Congress of the North American Continent, Division of Fertilizer and Soil Chemistry, 1980. 

It is possible to extract uranium from wet-process phosphoric acid... 

There are a number of practical synergistic systems that make use of organophosphorus compounds. A classic example is the combination of HDEHP and TOPO. The TOPO is thought to replace water or HDEHP in the coordination sphere of the metal. Some early work in this area included a study of the extraction of uranium in such systems (82). Commercial processes now exist for the recovery of uranium from wet-process phosphoric acid utilizing synergistic systems (83,84). Descriptive studies of such systems have also been made (85,86). 

Bock, J. Klein, R.R. Valint, P.L. Ho, W.S. Liquid membrane extraction of uranium from wet process phosphoric acid. In Sulfuric/Phosphoric Acid Plant Operations American Institute of Chemical Engineers New York, 1982 175-183. 

In the early 1980s eight commercial plants in the United States and one in Canada were recovering uranium from wet-process phosphoric acid. At about the same time, a commercial uranium facility was constructed at the Chimie Rupel subsidiary-of-Societe de Prayon-inr Belgium, and others were planned in France by Rhone-Poulenc and APC, using their own technologies, and in Japan by a consortium headed by the Power Reactor and Nuclear Development Corporation, usirg its own process. 

Tributyl and trioctyl phosphine oxides are also available commercially as extractants. The extraction of uranium from wet process phosphoric acid, as U , can be effected with the latter (TOPO) in kerosine. Other processes devised for this purpose are based on commercial octyl pyrophosphoric acid, or the synergistic mixture 2-ethylhexyl phosphoric acid/trioctyl phosphine oxide in kerosine. For extraction of U +, monooctylphenyl/dioctylphenyl phosphoric acids in kerosine can be employed. TOPO can be used for the extraction of Cr, Zr, Ee, Mo and Sn [18] and for making quantum... 

An especially intriraing use of liquid-membrane technology, reported for the first time recently by Fox and Hayworth et al.," is the recovery of uranium from wet process phosphoric acid (WPPA). In the manufacture of fertilizer fiom phosphate rock, the acid is solubilized by treatment with sulfuric acid. In addition to HjP04, this crude leachate can contain up to 0.18 g/L of uranium. Under oxidizing conditions this occurs as the uranate ion, UO . Solvent extraction (SX) processes have been developed to recover die uranium values. One of the most common of these uses a mixture of di-(2-ethylhexyl) phosphoric acid (D2EHPA) and trioctylpbosphine oxide (TOPO) in kerosene solution. The chemistry of solvent extraction is as follows ... 

Dickens, N., Davies, G.A. Rose, M. (1984) The extraction of uranium from wet process phosphoric acid using a liquid surfactant membrane system. Proceedings of the Symposium on Liquid-Liquid Extraction Science, Extraction 84, 27-29 November, Dounreay, Scotland, pp. 69-81. 

The LEM technique was first proposed by Li (1) in the 1960s as a possible industrial technique for the separation of substances from aqueous solutions. Initially, Li s work concentrated on the separation of hydrocarbons and, later, on the removal of dissolved constituents (phenols, phosphoric acid, sodium nitrate, and ammonia) from aqueous solutions. During the 1970s, research on this technique was extended to the removal of copper from acidic leach solutions and the extraction of uranium from wet-process phosphoric acid (2-3), Research in Japan involved the extraction of NH3, Cr Hg , Cd ", and Cu " from industrial waste waters (4), Draxler, Furst, Protsch, and Man investigated the extraction of zinc from a waste water at a rayon plant in Austria (5-6), However,... 

The ELM process has been used extensively to extract organics from aqueous feed, e.g., phenol from water (13-15), in hydrometallurgical separations, like zinc from waste water (16-18) and uranium from wet process phosphoric acid (19,20), and in the recovery of rare earth metals (23,24),... 

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