The purpose of this work was to recover uranium from residue originating from the production of molybdenum -99. Carbonate solutions containing hydrogen peroxide or oxygen gas as oxidants were used as leachants. Experimental parameters included: different peroxide and carbonate concentrations, dissolution time and temperature. Results indicate complete dissolution of the residue at 60 oC, after thirty minutes, in ammonium carbonate solution enriched with hydrogen peroxide. Almost two hours were needed to achieve the same extent in the presence of oxygen. The yield and rate of uranium extraction were found to increase as a function of both temperature, in the range of 25-60 oC, and hydrogen peroxide concentration. The leaching kinetics were determined for various leaching conditions and the activation energy was found to be 45.5kJ/mol. The order of reaction with respect to uranium concentration was found to be unity. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Materials Science and Metallurgical Engineering / unrestricted