Visualization of flow behavior during bioleaching of waste rock dumps under saturated and unsaturated conditions

A simulation framework is outlined for the analysis of the saturated and unsaturated flow behaviors within a waste rock dump. The traditional inherent “black-box” approach for treating waste rock dumps has resulted in generalizations that sometimes prove inaccurate. The hydrodynamics play an important role in terms of leaching reaction kinetics, heat and solute transport. The coexistence of saturated and unsaturated flows within the dump makes the flow behavior complicated. In this study, X-ray CT (SOMATOM Sensation 16) was used to obtain the real pore structure of the packed waste rocks. The meso-scale saturated flow process was visualized through solving the governing equation by the COMSOL Multiphysics software. The velocity field depends strongly on the distribution of channels, pore connectivity and curvature. The macro-scale unsaturated velocity field within the dump was obtained. The information drawn from this model can be used to improve the understanding of the hydrodynamics within waste rock dumps.