Leaching characteristics of uranium from El-Missikat mineralized granite

• Published in: Euro-Mediterranean journal for environmental integration Vol. 6; no. 1; p. 14
• Main Authors: Orabi, Ahmed H., Zaki, Salah A., Bayoumi, Moustafa M., Ismaiel, Doaa A.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.04.2021; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Chromium; Contaminants; Copper; Diffusion layers; Dissolution; Earth and Environmental Science; Earth Sciences; Environmental Chemistry; Environmental Management; Environmental Science and Engineering; Granite; Inductively coupled plasma; Iron; Kinetics; Leaching; Liquid phases; Mineralization; Minerals; Nuclear power plants; Original Paper; Particle size; Phase ratio; Reagents; Scanning electron microscopy; Shrinking core model; Spectrophotometry; Sulfuric acid; Trace elements; Uranium; Waste Management/Waste Technology; Waste Water Technology; Water Management; Water Pollution Control; X-ray fluorescence; X-ray spectroscopy; Yellow cake; Eastern Desert; Egypt; Uranium dissolution; Shrinking core model; Malonic acid; El-Missikat; Sulfuric acid
• ISSN: 2365-6433; 2365-7448
• DOI: 10.1007/s41207-020-00214-7

In this study, the dissolution of uranium from El-Missikat mineralized granite using either malonic or sulfuric acid was investigated, along with the kinetics of this process. The composition and leaching characteristics of the El-Missikat granite were explored. The mineralized granite and the residues remaining after it had been leached by the acids were characterized by X-ray fluorescence, inductively coupled plasma optical emission spectrophotometry, and scanning electron microscopy–energy-dispersive X-ray spectroscopy. The results of this study were used to select the optimal leaching agent, which yielded the leach liquor with the lowest contaminant levels and the highest uranium content, thus enhancing the purity of the yellowcake product in the separation unit. The effects of parameters such as the malonic or sulfuric acid concentration, the leaching time, the temperature, as well as the solid/liquid phase ratio (S/L) on the dissolution rate were studied separately. The dissolution study showed that 1.5 M sulfuric acid and 2 M malonic acid dissolved approximately 90% and 92%, respectively, of the uranium in the granite at 25 °C when the particle diameter was < 74 µm and the phase ratio (S/L) was 1/4. The smallest amounts of the other elements in the mineralized granite (Fe, K, Ca, Al, Ti, Y, Pb, Cu, Zn, As, Co, Cr, and V) were obtained when malonic acid was applied rather than sulfuric acid. The kinetics and thermodynamics of the dissolution process using either acid indicate that the shrinking core model is applicable to this process, and that the reaction is controlled by the diffusion of acid and U(VI) through the porous product layer.