Alkaline selective leaching of uraniumfromcarbonate-rich black shale wadi naseib, southwestern sinai, Egypt

Author(s): AhmedR.Bakry, SalehM.El-Hady

A technological sample assaying 1600 ppm U and about 2.8% CuO in a carbonate-rich black shale host rock has been collected fromWadi Naseib area of Southwestern Sinai. The XRD analysis has revealed that the predominating carbonate mineral is ankerite which the clayminerals are found to be represented by kaolinite, montmorillonite and illite. Due to the mineralogy of the working ore material, it was necessary to apply carbonate leaching for selective leaching of uranium. This is due to the fact that acid leaching is not suitable due to the present of high carbonate content besides avoiding the co-leaching of the present copper values. After studying the relevant alkaline leaching factors for dissolving about 97% of uranium from the studied working sample are 50 g/l Na2CO3 and 20 g/l NaHCO3, S/ L ratio 1/3, agitation time 1.5h at room temperature. Uranium was recovered from the carbonate leach liquor through the anionic exchange resin Lewatite Monoplus M 500 and from the eluate, uranium was precipitated by sodic decomposition to obtain Na2U2O7 product.

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