الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
ABSTRACT
The studied area, Abu-Rushied, is located between longitude 34o 46` to 34o 46` 35`` E and latitude 24o 37` 16`` to 24o 38` N, South Eastern Desert, Egypt. The main rock units of Abu Rushied area from the mineralogical point of view are the cataclastic group and the lamprophyre dykes cutting through it.
The main aim of this work is to develop a selected process to purify uranium from its mineral ores concentrate, to reach international standard yellow cake. the present thesis is directed to investigate, the following;
1- Study a suitable leaching reagent of uranium for Abu Rushied ore.
2- Assess the kinetics model for leaching of working ore.
3- Investigation of uranium extraction by TOA from sulfate medium.
4- Investigation of uranium extraction by dynamic ion exchange from sulfate medium.
Different parameters affecting the leaching of uranium from its ore using carbonate, sulfate, and nitrate solutions were studied. Parameters affecting the leaching efficiency are grain size, leaching reagents concentration, solid to liquid ratio, agitation time, temperature, and adding oxidizing agent if necessary.
It is found that leaching by nitric acid is more convenient than carbonate or sulfuric acid leaching in terms of efficiency of uranium recovery, low iron concentration as well as agitation period.
The leaching process was be well described by the shrinking core model, and the rate controlling step for the uranium leaching from Abu Rushied ore is the inner diffusion of chemical reagent.
the activation energies of uranium leaching reaction from Abu Rushied ore by diluted nitric acid is found to equal 10.3 kJ mol−1.
Analysis of kinetic leaching by nitric acid was found to follow the following relation;
[1 − 3(1 − α) 2/3 + 2(1 − α)] = Ќ
Whereby α is uranium conversion, P is particle size, C is acid concentration, and Dm is nitric acid/Abu Rushied ore mass ratio. This equation indicates that the leaching of uranium is highly dependent on particle size, mass ratio, and acid concentration.
Two processes were investigated to purify uranium from leach solution based on liquid-liquid extraction and ion exchange.
Purification by solvent extraction is based on the use of TOA. The factors affecting the extraction of uranium from pure sulfate media included effect of different diluents with different TOA, uranium, and sulfuric acid concentrations as well as the effect of contact time, hydrogen ion concentration, H2SO4 concentration, Na2SO4 and K2SO4 concentrations. Effect of TOA and uranium concentrations have been also studied. The best conditions obtained from this section for uranium extraction are: Kerosene is the best used diluents according to its low value of dielectric constant, contact time of 5 minute, pH range 0.2 to 0.3. Uranium extraction is found to decrease with increasing the H2SO4 concentration and increasing the Na2SO4 and K2SO4 concentrations. Uranium extraction increased with increasing TOA concentration and increase in the organic phase with increasing uranium.
In addition, the influence of certain factors affecting the extraction of uranium from the nitrate leach liquor of Abu Rushied ore included TOA concentration, pH, contact time, temperature, and aqueous to organic phase ratio have been studied.
The best conditions obtained for uranium extraction are: 5% TOA in kerosene, pH of 1, 5 minutes as contact time. Higher temperature decrease uranium extraction, and uranium extraction slightly decreased with increasing the A/O phase ratio which gives total extraction of 99.5 % at 350C and phase ratio equal unity.
Uranium extraction percent of A/O phase ratio from 1 to 10 and 1 to 5 extraction stages were theoretically calculated, and found to be close to the experimental results. The experimental results indicated that the required extraction can be obtained from theoretical calculations with a good accuracy.
Stripping of uranium from the loaded TOA organic solvent was investigated using H2SO4 or HCl as stripped agent. The influence of certain factors affecting the stripping included stripped concentration, contact time, temperature, and aqueous to organic phase ratio have been studied. The optimum conditions obtained from these results are the following;
9M sulfuric acid, 10 minutes as contact time, phase ratio equal unity at 40 oC which gives about 99.2% uranium stripping.
In this concern, purification of uranium by ion exchange was carried out using Lewatit anionic resin. Different parameters affecting the extraction of uranium from nitrate leach liquor using Lewatit anionic resin were studied. It was found that the extraction efficiency of uranium reaches a maximum value at pH ~ 1.5. Shaking time of 25 minutes was found to be sufficient for reaching equilibrium. The effect of temperature was studied and the data obtained indicated that the sorption process increase with increase temperature till reach 50 oC. While R/S equal 1/30 is suitable for pilot scales and increase sulfate concentration decrease uranium extraction, 82% of uranium was extracted at optimum conditions.
Some factors affecting uranium elution efficiency from loaded resin were studied. These factors include the effect of different eluents, agitation time, and temperature. 1.0 M NaCl, 40 minutes, 50oC gives around 98% elution efficiency. Finally, application of optimum conditions upon one run batch dynamic ion exchange was reported.
Aflow sheet was developed and given for the two processes studied. Analysis and specification of the final uranium obtained for the two processes are given together with the international standard of nuclear grade yellow cake.
It is found that the uranium obtained in the two cases met the international standard of yellow cake. However, the liquid-liquid extraction process is found give a more cleaner product than that of the ion exchange processes.