Reactive Transport Simulation of Uranium ISL at the Block Scale: A Tool for Testing Designs and Operation Scenarios

This study details the development of a 3–D reactive transport modelling approach dedicated to simulate acid ISL production of uranium. The model relies on an appropriate description of uranium bearing aquifer: 3–D geological model, based on geostatistical simulation of uranium grade and hydrodynamic parameters. Also, a correct assessment of the chemical reactions at stake is necessary. The ISL operations are then simulated using the versatile reactive transport code HYTEC. Among other simulation results available, the evolution of the uranium concentration at production wells can be predicted. The model was applied at the technological block scale (50 technical wells) on the KATCO mine in Kazakhstan. The simulation reproduces the behaviour in terms of uranium recovery and acid consumption. It also helps quantitatively understanding the behaviour of the exploitation, and identifying weak spots of the leaching process. Finally, it is possible to use the simulation to optimize the production (increased uranium yield or reduced reagent consumption) by comparing the results under several production scenarios (injection rates, fluid composition and well field geometry). (author)