LEACHING AND RECOVERY OF RARE EARTH ELEMENTS FROM ALTERED ALKALINE GRANITE ROCK FROM NUSAB EL-BALGUM AREA, SOUTH WESTERN DESERT, EGYPT.

Leaching and recovery parameters controlling the releasing of rare earth elements from Nusab El-Balgum altered alkaline granite rock are studied and determined. The optimum conditions of batch leaching are attained at 3 M of HCl concentration, 200 rpm stirring speed and 1/6 solid to liquid ratio for 180 min contact time at room temperature. Under the optimized conditions, the ?REEs leaching efficiency was 92.4%. The thermodynamic data showed positive values of both ?H and ?S which indicates that the leaching process is indeed endothermic and random while the obtained negative values of ?G indicate that REEs dissolution process is spontaneous in nature. Three-liquid-phase system (Cyanex 272/PEG 2000/(NH4)2SO4–H2O) is employed for rare earths separation from associated impurities in the obtained leach liquor. The relevant factors controlling and selective enrichment of those ions in aqueous salt phase are investigated. The optimized conditions are occurred at pH 2, 3g of PEG, and 1.6 M of (NH4)2SO4. Separation of REEs ions from bottom aqueous phase after removal of impurities is achieved and precipitated by adding oxalic acid.