Extraction of uranium from commercial phosphoric acid by DEHPA/TOPO process is a well-developed process on the commercial and pilot plant scale. Commercial phosphoric acid contains certain anions such as Cl − , F − and SO 2− 4 in varying concentrations. The presence of such anions could have a negative effect on the extraction process.This paper investigated the effect of Cl − , F − and SO 2−4 anions present in commercial wet phosphoric acid on the uranium extraction process. The effect of adding SiO 2 which complexes with F − and other anions was also studied. The results obtained showed that these anions formed complexes with UO 2+ 2 and therefore had a negative influence on the extraction of uranium from laboratory and commercial phosphoric acids. This effect was strong in the case of F − followed by SO 2− 4 and much less for Cl − . Addition of SiO 2 was found to negate the effect of F − and other anions and to exert a positive effect on uranium extraction. KeywordsExtraction · uranium · DEHPA/TOPO · anions · phosphoric acid AcknowledgementThe authors would like to express their thanks to the General
Cadmium is present in all types of phosphates in concentrations ranging from 1 -90 ppm. During digestion of phosphates by concentrated sulfuric acid to produce phosphoric acid by the wet method 70-80% wt of cadmium is transferred to the phosphoric acid while 20-30% wt remains in solid phosphogypsum. Cadmium is then transferred from the phosphoric acid to the fertilizers. Most environmental regulations try to reduce the percentage of cadmium in the fertilizers. Several studies were carried out to reduce the concentration of cadmium in phosphoric acid. Some used ion-exchange techniques. Others used liquid-liquid extraction by alkaline solvents such as trioctylamine (TOA). Several investigators used commercial phosphoorganic solvents such as Cyanex 302 and Cyanex 93. This paper studies the extraction of cadmium from phosphoric acid by trioctylphosphine oxide (TOPO) solvent in kerosene. The extraction was enhanced by the presence of Cl − in the solution. The temperature had a negative effect on the extraction. Increasing the concentration of cadmium while keeping chloride ion concentration constant decreased the extraction. The extraction was increased by increasing the concentration of the phosphoric acid.
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