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Abstract
The work is mainly concerned with chemical studies on the behaviour of rare earth elements during manufacture of phosphoric acid from Abu-Tartur phosphate ore. The studies proved that REEs concentrated in phosphogypsum waste. Also, investigations of the leaching of REEs from phosphogypsum were studied. Therefore, the work is divided into three main parts as follow:
І. The first part indicates the introduction for resources and distribution phosphate rock in Egypt and phosphoric acid production (wet process). Also, a vast literature review concerning with rare earth elements until (2007 year) was made in the following points:
A. Nature, discovery and origin of names.
B. Resources and production in some countries.
C. Reserves and distribution in all the world.
D. Methods for determination from complicated methods to simple methods and the method which used in this thesis.
E. Application of rare earth elements.
The results of the present work indicate that agitation and heap leaching can be used easily for leaching of REEs from phosphogypsum waste. The chemical analysis of the REEs pregnant solution after leaching processes indicates the presence of some impurities e.g., P2O5, CaO, MgO, Fe2O3 and U. Therefore, purification of the pregnant solution from these impurities at different pH values was made. It is found that pH 4 is the suitable to remove most of impurities and beneficiate the concentration of REEs in the pregnant solution. Also, in this work separation and concentration of REEs from phosphogypsum waste by ion exchange resin was indicated.