The extraction of gold, copper or other minerals through the heap leach process has improved greatly over the past few years. Heap leach pads can contain over a billion cubic feet of material and be over 300 ft high.

Numerical modeling of heap leach pads can provide value in three specific areas: 1) Improved efficiency of operations, and, 2) estimation of drain-down times during heap leach pad closure, and, 3) estimation of long-term performance of earth cover systems. Problems are commonly encountered in numerical models of heap leach pads due to the following reasons:

• Heap leach pads typically have irregular 3D geometry and do not lend themselves to 2D models.
• Heap leach pads are operated in a constant unsaturated state and therefore require a numerical model capable of handling the particular nonlinearities associated with unsaturated seepage modeling.

SVFlux has been successfully applied to heap leach pad applications and proven itself a valuable tool in heap leach pad analysis. Specifically, the following features make SVFlux the premier tool for evaluating heap leach pad operation:

• The automatic mesh generation allows quick meshing of complicated 3D problems.
• 2D and 3D analysis are available.
• Advanced formulations and algorithms to handle nonlinear unsaturated analysis.
• Highly detailed mesh generation allows representation of fine features such as the overliner material, preferential flow paths, multiple soil regions, irregular internal geometry, or decreasing hydraulic conductivity with depth.
• Automatic mesh refinement allows accurate calculation of wetting fronts in dry soils.
• Surfaces of existing topography can be created and input into the model from survey data.
• Climate data such as precipitation, temperatures, and net radiation may be incorporated into the model for analysis of long-term cover performance.
• SVFlux may also be coupled with ChemFlux to predict concentration levels in various areas of the heap leach pad. The numerical models may therefore be used as tools for improving the efficiency of the operation.