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Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones at Abu Rusheid area. The secondary uranium minerals occur as hair-like radiated spots and thin micaceous flakes with canary and yellow color, which are deposited along the small cracks and microfractures of altered gneiss and lamprophyre dyke and coat surfaces of hematitized rock. The radiometric measurements proved that the uranium content increases from sericitized gneiss (average 317.9 ppm) to ferruginated gneiss (average 863.1 ppm) and then to altered lamprophyre dyke (average 1352.7 ppm). The latter is the most radioactive zone along the NNW shear zones and is considered as a good trap for the uranium leached from the host rock due to the high ability of iron oxides and clays to adsorb radioactive elements from their solutions. Therefore, the present work focuses on the uranium leaching from Abu Rusheid area using sulfuric acid. The effect of sulfuric acid concentration, liquid/solid ratio, contact time, and leaching temperature on the leaching efficiency has been investigated. The data obtained show that about 74.0% of uranium can be leached successfully under the following conditions: sulfuric acid concentration 4 M, liquid/solid ratio 10 mL/g, room temperature, 6.0 h. The leaching kinetics is well interpreted with shrinking core model with control by diffusion through a porous product layer. The diffusion-controlled process is characterized by the activation energy of 6.3 kJ mol–1. [ABSTRACT FROM AUTHOR]

An efficient natural bioextractant, orange peel extractant, was applied to recover uranium as one of hazardous elements. Batch experiments were carried out to determine the effect of various factors on the uranium extraction using a synthetic standard solution. These factors include the diluent type, pH, solvent concentration, contact time, and temperature. Under the optimum conditions (pH 4, A/O = 3/1), the maximum saturation capacity of the orange peel extractant for uranium reaches approximately 54.5 mg/g. The extracted uranium ions were almost completely eluted with NaCl/H2SO4 (1 M each). The procedure was applied to real sulfate leach liquor of a clay stone sample from Southeastern Sinai, Egypt. [ABSTRACT FROM AUTHOR]