Morphological Variations During Carbonate Leaching of Uranium from Indian Alkaline Host Rocks

Leaching plays a pivotal role in uranium extraction process. The intrinsic behavior of the industrial-scale leaching process is governed by microscopic phenomena such as microstructure of uranium and gangue minerals in the ore, diffusion and chemical reactions between molecules of solvent and solid phase during leaching. The present study includes in-depth microscopic investigations on morphological changes that occur during leaching of pure materials and synthetic mixture representing Indian uranium ores hosted in alkaline rocks vis-a-vis actual ores. Leaching phenomenon was analyzed with the aid of extensive characterization studies carried out on several feed and leached samples using optical microscope, X-ray diffractometer and scanning electron microscope. The dissimilar leaching behavior of Tummalapalle and Gogi uranium ores in carbonate media could be attributed to the nature of uranium mineralization and the association of uranium values with pyrite, a reactive gangue mineral, present in the ores. Leaching efficiencies and morphological changes observed were corroborated.