الفهرس 
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Abstract
In the second half of the last century, uranium has become one of the most important energy resources. Besides using power reactors for the generation of electricit y, nuclear energy is also used for the production of several radio-isotopes which are greatly required in the fields of agriculture, industry, medicine, etc. While uranium is considered the primary nuclear fuel, thorium comes next in importance in breeder reactors. Increasing uranium demand and rapid exhaustion of most conventional uranium ores beside importance of local production, woul d orient the trend towards low-cost non-conventional methods for treatment of low grade ores as well as to non-conventional uranium resources. Among the latter, monazite occupies a leading position. The present thesis is composed of a three main chapters, each of which can be summarized as follow: I. IN THE FIRST CHAPTER, Introduction a full literature survey concerning uranium with a special focus on monazite was introduced. The main points that have been discussed through this chapter
can be summarized as follow: i- The definition of uranium and their discovery. ii- Exploration of the different minerals containing uranium, their
distribution and reserves all over the world.
iii- The properties of uranium atoms and ions, which include the electronic configuration, position in the periodic table, oxidation states, magnetic and spectral properties. iv- The different methods for the physical and chemical processing of monazite and uranium were presented and reviewed. v- Focusing on the resources of uranium in Egypt, and discussing the physical and chemical processing techniques utilized in Egypt for the processing of monazite mineral derived from Egyptian black sands. vi- Reviewing of the methods concerning the separation of uranium. vii- The several applications involving the use of the uranium were
presented and exhibited in detail. viii- A brief review on solvent extraction of uranium from acidic
solutions. ix- Observations on uranium extraction. II. IN THE SECOND CHAPTER
, the utilized chemicals, reagents, materials, instruments and equipments were stated. We can
summarize the experiments which have been made in this work as follows: i- Chemicals and Reagents.
ii- Instruments and Equipments iii- Preparation of rare earth hydrous oxides, thorium and uranium oxides cake from Egyptian monazite iv- Demonstration of the analytical procedures for determination of rare earth elements, thorium and uranium in different media. v- Sulphuric acid digestion procedure for monazite was carried out in order to get a rare earth, thorium and uranium cakes. vi-Studying of Thorium, rare earth elements and uranium Precipitation Efficiency vii- Methods for different applied solvent extraction schemes for
uranium separation and purification were also presented. III. IN THE THIRD CHAPTER, the results of experimental
chapter were declared and discussed. This chapter consists of three main parts; i) In the first part,
The Conventional concentration and uranium purification processes:- During the application of the sulfuric acid digestion process for monazite mineral and precipitating its Th, REEs group and U constituent separately in different pH controlled processes, some additional cautions
and steps were carried out to enhance the purity properties of the three products, particularly to release the best possible recovery and purity ratio
of uranium content. The process was carried out for 10 gm of monazite mineral (~ 50%) and the additive steps were relating to the washing process.
It was found that most of uranium percent was collected in a concentrate at pH 6 but after 6 washing times with the pH adjusted water to
the same various pH values of the different precipitation steps. The uranium concentration increases from 12.86 % by direct precipitation to 19.1 % after washing by acidified water.
The produced uranium concentrate was subjected to the normal purification procedures after caustification, dissolution in nitric acid and contacted with TBP as solvent in multi-contact then recovered via its stripping with cold water (1:1). ii)
In the second part: 1- Recovery of uranium from mother sulphate solution by caustification – carbonate leaching process: In this process, the sulphate leach liquor, which produced after mineral digestion (10 g monazite) with sulfuric acid and dissolute with cold
water, was subjected totally to Caustification step for precipitating all its cationic components as hydrated oxides. The produced hydrated oxide was washed several times with water, dried, and treated with alkaline carbonate solution composed of 40% vol. 1M Na2CO3, 50% vol. 1M NaOH and 10% vol. (30%) H at 60ºC in order to separate the maximum content of uranium selectively by forming tri-carbonate complex. 2 It was found that about 90% of uranium content can be recovered after five times of carbonate washing experiments while more than 99% could be obtained after ten carbonate washing experiments with ppms of REEs and thorium contamination. Up-scaling the experiment to 100 gm mineral / batch gave less effective recovery for uranium due to the difficulty of uranium leaching in the up scales levels due to the high economic
burdens. O2 2- Extraction of uranium from carbonate leach solution:- Extraction of U(VI) from carbonate solution can be fulfilled in one
fast step by applying tri-butyl amine as an extractant which behaves as liquid anion exchanger (fast easier and economical way). The extraction parameters were adapted first for the solvent to be compatible with the working carbonate, peroxide and temperature to get the maximum extraction percent in one stage. These conditions were 5 vol. % Tri-butyl amine / kerosene- 15 minute contact with phase ratio (1:1) which produce 99.85% uranium purity and less than 0.01 % of each of Th & REEs. Also it was found that up scaling the experiment is not trusted to be applied. II. In the third part: • Oxalic- Nitrate- TBP adapted process for uranium purification: The process of the present section started after monazite sulphuric acid digestion and dissolution at optimum conditions. The clear sulphate solution (liquor) is treated with sodium hydroxide after precipitation with ammonia solution to prepare the mixed hydrous oxides of the three main mineral cationic components namely rare earth elements as a group, thorium and uranium. The cake was washed thoroughly to be free from excess soda and
dried. The cake was dissolved completely in nitric acid 1N with gentle stirring avoiding suspension for easier further filtration processes (filterable
rafinates). The aqueous acid solution was then precipitated at pH 5.5 with 10% sodium hydroxide. The filterable mixture was then filtered of for clean
pure rare earth nitrates and hydrated thorium & uranium concentrate. The produced precipitate contains mainly all thorium and uranium constituent of the mother sulphate starting liqueour with a minor rare earth percent. The precipitate was washed carefully then redissolved again after
drying in a slight excess of stiochiometric nitric acid and then heated till near dryness. Extraction and recovery of thorium and uranium in their highest
possible purity and recovery percents applying TBP/Kerosene extraction thorium oxalate precipitation – uranium water stripping new adapted
scheme- thorium can be extracted with more than 99.9% percent recovery containing 5-15 ppm uranium, while uranium can be extracted with more
than 99.5% percent recovery and more than 99.9% purity. The best experimental extraction-precipitation stirring condition to obtain the aforementioned recovery and purity percents for both elementswere:- Opening: - conc. H2SO (W /V) (acid / ore ratio) 1: 1.6Dissolution: - ice water 1:20
First Precipitation: - NH4OH 1:1Caustification: - 10% NaOH Dissolution: 1M HNO34Second precipitation: 10% NaOH at pH 5.5-6 Dissolution: 7M HNO 3 Drying Organic concentration: - 40-50% TBP/K Scrubbing: - scrub solution 5 (2M HNO) Aqueous: organic ratio: - 1:5 Precipitant concentration: - 1.5 M oxalic acid Stirring time: - 45-60 minutesTemperature: - 40-50 ºC Stripping: - strip solution cold water (1:1) Last precipitation: - 10% NaOH, pH 6.