Includes bibliographical references.This thesis describes the development and execution of an experimental leach programme and the use of a techno-economic model to determine improved operating set-points for a uraninite/uranophane ore body, for plant-scale implementation, that consistently maximise value delivery. A mineralogical investigation of Rössing leach samples indicated that liberated uraninite remains in the leach residue, providing evidence of non-optimal leach conditions such as prevailing redox potential, incomplete leaching within the normal residence time or galvanic hindrance. Specific focus was, therefore, placed on the effect of oxidation reduction potential (ORP) on uranium extraction and reagent consumption and the determination of an improved ORP set-point as a function of ore type, residence time and the economic environment
