Uranium extraction enhancement form phosphoric acid by emulsion liquid membrane
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Uranium extraction enhancement form phosphoric acid by emulsion liquid membrane H. M. Elsayed • E. A. Fouad • N. M. T. El-Hazek • A. K. Khoniem
Received: 2 April 2013 Ó Akade´miai Kiado´, Budapest, Hungary 2013
Abstract This work is mainly concerned with the uranium extraction from phosphoric acid commercially produced by Abu Zaabal Fertilizers and Chemical Co., Egypt. This target would realize a dual purpose where the phosphate ore is considered as an alternative source of uranium besides eliminating its environmental contamination. The applied procedures are that of the new technology of emulsion liquid membrane. Authors have indeed pointed out that the variables explored still leave open to question the roles of stripping at the internal interface as well as the bulk transfer of uranium in the internal phase. For this purpose, two reducing agents are studied as additives to two organic solvent systems; namely the organophosphorous synergistic mixture of D2EHPA/TOPO as well as the tridodecyl amine. The relevant factors have first been optimized upon synthetic uraniferous phosphoric acid solution followed by the application upon the commercial acid after purification. These factors include the concentration of solvent system and the used emulsifier, acid concentration of the external and internal phases besides the nature and concentration of the reductant added to the internal phase. In addition, the permeation time as well as the oxidation state of the external phase was studied. All H. M. Elsayed N. M. T. El-Hazek Nuclear Materials Authority, P.O. Box 530, Maadi, Cairo, Egypt E. A. Fouad (&) Chemical and Materials Engineering Department, Faculty of Engineering, Northern Boarder University, P.O. Box 1321, Arar, Kingdom of Saudi Arabia e-mail: [email protected] A. K. Khoniem Chemistry Department, Faculty of Science, Zagazig University, Zagazig, Egypt
these factors have indeed been studied under different mixing speeds ranging from 300 up to 1,000 rpm. Ascorbic acid concentration, 1 % as an additive to the internal phosphoric acid phase (40 % P2O5) resulted in 95 % uranium extraction efficiency at the lower speed of 600 rpm. Keywords Uranium Emulsion liquid membrane Phosphoric acid D2EHPA–TOPO
Introduction Efforts are being made worldwide to investigate the newer resources of uranium to meet the required demands. Among the secondary resources of uranium, natural phosphates are found to be an important resource for uranium and REE [1]. Phosphate rock is essentially composed of tricalcium phosphate which exists in the form of apatite mineral that could accept various ionic replacements. This is due to the fact that the hexagonal crystal lattice of the apatite mineral is adequately open to permit several cationic and anionic displacements. Among these displacements, U, V, REE, etc. can be found in the rock and where the average uranium concentration varies actually between wide limits but generally in the ranges of 50–200 ppm. During the acid digestion of phosphate rocks, most of the uranium (*90 %) r
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