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a b s t r a c tThe Egyptian phosphogypsum waste is treated using sulfuric acid prior the ammonium sulfate production. The relevant factors that would affect the removal efficiencies of some impurities are studied. The optimum conditions of the treatment are 8 M sulfuric acid solution and 1/4 solid/liquid ratio for 30 min contact time at 80 C. Moreover, the optimum conditions of the ammonium sulfate preparation are 10 g of the suspended impure or purified phosphogypsum in 40 ml of 3% ammonium sulfate solution (as initiator), 1/4 solid/liquid ratio at pH7 at an addition of an excess ammonium carbonate, and 150 rpm stirring speed for 4.0 h contact time at 55 C as well as the 5 mg of barium chloride is added to remove the radium in the ammonium sulfate product. Finally, the ammonium sulfate is crystallized and the chemical analysis of the product shows 20% nitrogen and 23.6% sulfur. Therefore, the purity of the obtained ammonium sulfate is 95% from the purified phosphogypsum.

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A new adsorbent has been developed to reduce the concentration of iron in crude Egyptian phosphoric acid. This adsorbent has been formed by the treatment of silicate compound derived from clay mineral with π organic acceptor ligand to carry out the exchange of ions as well as complexation with iron. Several parameters (shaking time, temperature, sorbent mass, and batch factor) have been studied. The adsorption of iron from crude phosphoric acid was investigated. The various methods to characterize the adsorption of iron on organosilicon compound (OSC) were collectively evaluated in this study. According to the Langmiur model, the maximum monomolecular capacity (Q º ) is 122 mg/g and 122 mg/g with Freundlich model for an initial iron concentration of 2.37% contained in crude phosphoric acid. Characterization studies such as x-ray diffraction, infrared spectroscopy and electron scanning microscope were investigated to substantiate the nature of iron-OSC complexes.

T HE PRESENT study deals with the purification of crude yellow cake produced through sulfate leaching of Gattar mineralization, Eastern Desert-Egypt. The Gattar yellow cake is purified through dissolving it in hydrochloric acid which dissolves about 95% of uranium content in the studied cake. Uranium extraction was obtained from the prepared pregnant solution using a synergistic organic solvent mixture of 0.5M di ethyl hexyl phosphoric acid (D 2 EHPA) and 0.63M octanol in kerosene diluent. Different factors have been studied such as solvent concentration, stirring time, organic to aqueous phase ratio and temperature. The obtained loaded organic solvent was exposed to different concentrations of sodium carbonate to strip the uranium. After the stripping process, the uranium was precipitated using ammonia solution at pH 6.2. The product precipitate washed and dried then analysed. The analysis of the final precipitate shows upgrading of uranium concentration in the original cake from 46% to 76% while that of Fe has been decreased from 1.6% down to only 0.06% while that of Al and V have been totally removed.