الفهرس 
Chapter I IntroductionOnly 14 pages are availabe for public view
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Abstract
Wadi Nasieb considered as one of the most important mineralized areas in Egypt. It contains various mineral deposits e.g, Fe, Cu, S, Zn and Si beside gypsum, Dolomite, carbonaceous shale and quartz, which are widely distributed along the western Desert area.
Wadi Nasieb calcareous shale rocks of Um Bogma Formation of western desert are considered as one of the most promising occurrences for U beside the associated economic metal values e.g.,Zn, AL, Ni, REE…. etc. as well as Cu which is recorded for the first time in the present work. The main target of the present work is to study the processing of this ore material to recover its content of U, REE, and Cu, which are important for many technological and nuclear applications. For this purpose, a technological representative sample from Wadi Nasieb Calcareous shale ore material was collected. The mineralogical analysis of this sample revealed the presence of gypsum as the main mineral [CaSO4.2H2O]; together with quartz (SiO2).The secondary U mineral Sklodowskite, [MgO(UO3)2(SiO2)2(H2O)7]was recorded for the first time in the studied area by the present work. It is worthy to be mentioned herein that there is no identified minerals for REE which are probably adsorbed upon the gypsum mineral. Complete chemical analysis of the technological sample shows that, it is mainly composed of SiO2 which represents the main constituent (12.2%) beside Al2O3 (10%) and Fe2O3 (5.6%). K2O and MgO represent the much lesser constituents of the study ore material. Moreover, the sample was found to contain trace amounts of
TiO2, P2O5 and Na2O. High contents of CaO together with loss of ignition (25%) which reflect the Calcareous shale nature of the studied ore material.
Also, the chemical composition of the study ore material shows the presence of 0.2% of U, 2.7% of Cu, 0.18% of REEs. With respect to recovery study, H2SO4 acid agitation leaching process was applied upon the raw ore material for dissolving both of U, Cu and REEs with dissolution efficiencies of 98.5%, 96.7%, and 95.4 respectively. The applied optimum leaching conditions were 200g/L H2SO4 acid concentration, S/L ratio of 1/4 with stirring time for 4h at leaching temperature of 80oC.
The experimental data were well interpreted with a shrinking core model with U with diffusion controlled. its leaching kinetics using H2SO4 revealed that the reaction is controlled by diffusion through a porous ‘‘product’ ’layer, and since no insoluble product forms, it is inferred that the insoluble oxide minerals (quartz, etc.) associated with uranium play the role of the ‘‘product’ ’layer. As a matter of fact, the leaching rate follows actually the kinetic model
[1-3 (1-x)2/3 + 2(1-x)]=kdt with an apparent activation energy of the leaching reaction of uranium, from Wadi Nasieb ore by sulfuric acid was obtained from Arrhenius equation to equal. 16.2 kJ/mol., the results of the kinetics study show that temperatures from the main factors influencing the uranium leaching process.
prepared sulfuric acid leach liquor was obtained by processing 250 g of the studied ground ore material 200 g/L of H2SO4 acid solution at S/L mixed ratio of 1/4 and stirring for 4h at 600 rpm and at leaching temperature of 80oC. After filtration and washing the total volume of the yielded sulfate solution became 2.5 L and pH=0.5. However, U was recovered via anion exchange resin by using Amberlite IRA400 from the sulfate solution. U was extracted at optimum loading conditions of pH 1.8 and contact time of 4 min. The saturated resin was directed to the elution process by using an eluant solution of 1M NaCl acidified with 0.1M H2SO4 to eluate about 98 % of the loaded U. Almost complete U precipitation (98.9 %) takes place by gradual addition of H2O2 solution together with continues stirring for 4 h at the optimum pH = 1.
After filtration, the prepared UO2(O)2.2H2O was washed, dried and calcinations at 850 oC for 1 h to obtain high pure U3O8.
The effluent solution free from U was subjected to REE recovery via their solvent extraction firstly, remove almost interfering metal ions of high concentrations such as Fe3+ as Fe (OH)3 and Zn2+ as Zn(OH)2. After filtration and washing, the filtrate containing REEs metal ions was heated at 80oC for reducing its volume to about 1L where REEs concentration increased to 400 mg/L. This solution was then directed to solvent extraction unit for extracting REEs by using D2EHPA. The optimum conditions in the loading of REEs process by using 1M D2EHPA in kerosene, at pH value 1, contact time 6 min, and phases volume ratios (O/A) was 1/1. While the type and concentration of the stripping solution was 0.5 M H2SO4 solution at phase’s volume ratios (A/O) 1/1 at shaking time 6 min.
By applying the overall the organic solvent extraction processes upon the working sulfate solution (900mL) of the working sulfate solution, it was found that1M D2EHPA in kerosene could be up taken about 548 mg of REE.
The strip solution rich in REEs was treated with 10% H2C2O4solution after stirring for 1h at pH1.2, The REEs were precipitated as RE2(C2O4)3 cake. The chemical analysis of the latter revealed that, it assays 81.5% of REEs beside 14.3% of Ca as the mainly presented interfering metal ion. For further purification, the precipitated REEs-oxalate cake was dissolved in 5% HCl acid solution. The prepared RE chloride solution were treated with NH4OH solution to precipitate RE(OH)3 cake free from Ca ions at pH 9.5, After filtration and washing, the obtained RE- hydroxide cake was washed and ignited at 650-700oC for 1h to produce the relevant RE2O3 which washed, dried and subjected to SEM-EDAX analysis.
Finally, A working flow sheet was designed for processing of the working calcareous shale ore sample.