An Integrated Process for the Removal of Cd and U from Wet Phosphoric Acid

Abstract

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 ionexchange 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 Na 2 CO 3 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.

Extraction of Cadmium from Phosphoric Acid Using Resins Impregnated with Organophosphorus Extractants

“…Ortiz et al combine a preliminary extraction of uranium by sorption on an ion-exchange resin prior to cadmium removal using a nondispersive solvent extraction process. 11 The combination of different EIRs might also be considered as a promising alternative, as the combination of several impregnated resins enables the separation of metals from multicomponent solutions. 38…”

“…Another way to improve the extraction, stripping, and recycling performance levels might consist in combining the treatment of industrial phosphoric acid by impregnated resins with other physicochemical processes. Ortiz et al combine a preliminary extraction of uranium by sorption on an ion-exchange resin prior to cadmium removal using a nondispersive solvent extraction process . The combination of different EIRs might also be considered as a promising alternative, as the combination of several impregnated resins enables the separation of metals from multicomponent solutions…”

“…To improve the applicability of solvent extraction systems, several impregnation techniques have been developed, including resin impregnation, , the use of liquid membrane systems, and more recently, hollow fiber systems. , The impregnation of resins with extractants makes it possible to convert the support into a chelating system − but with less expensive materials.…”

Potentiality of Alcoholic Purification of Abu-Zaabal Impure Phosphoric Acid for Selective Ion Exchange Recovery of Uranium

“…It was shown that the aminomethyl phosphonic resin Purolite S940 gives a promising sorption/elution behaviour working in small column extractions of U from phosphoric acid solutions. The aminomethylphosphonic resin duolite Es467 was found selective for the recovery of U from wet Process phosphoric acid [10,11]. Commercia aminophosphonic resins of Na -type as supplied involve Lewatit TP 260 (2.3 eq/L), Purolite S 940 (2.0 eq/L), Amberlite IRC 747 (1.75 eq/L) and Duolite C 467 (1.0 eq/L) [12].…”

Copper and cadmium extraction from highly concentrated phosphoric acid solutions using calcium alginate gels enclosing bis(2,4,4‐trimethylpentyl)thiophosphinic acid

“…Owing to the high toxicity of their products, fertiliser producers are under pressure from local and national administrations and as a result several technological approaches for removing cadmium ions have been reported 2–8. Nevertheless, optimum technical and economic results have not yet been obtained and a great deal of work on new alternatives for solving the problem is continually being proposed 9–19. These studies are based on non‐conventional liquid–liquid extraction processes such as emulsion liquid membrane processes, non‐dispersive liquid–liquid extraction and impregnated resins.…”