Insitu leaching: The effect of temperature and pressure on the permeability of uranium bearing rock

Abstract

This thesis concerns the insitu leaching of low grade uranium deposits that would be infeasible to mine by conventional mining methods. Initially, the report deals with the actual leach mining process, from well construction, to the extraction of values from the leach solution. The main area of research, however, centers around the permeability characteristics of the rock. The effect of temperature and pressure on rock permeability epitomizes this study, and is determined by laboratory testing. The purpose of this study is to observe the effect of these parameters on rock permeability and hence its leachability. The experimentation is carried out using Navajo sandstone samples to simulate the uranium measure rock. These samples are subjected to different temperatures of lixiviant (in this case, air), and injection pressures, and the coefficient of permeability is calculated from Darcy's law. A mathematical model of the problem is presented in the literature review. This model incorporates the leaching process with the different variables associated with it including; oxidant concentration, velocities of flow of the lixiviant along the different streamlines, guard wells, dispersion of the lixiviant, and uranium concentration.