X-Ray Imaging of Fluid Flow and Reactive Transport in Dual-Porosity Media: Implications for Heap Leaching

Heap leaching is a hydrometallurgical technique for extracting metals from low-grade ores and plays a vital role in supporting the global shift toward sustainable energy systems. While valued for its operational simplicity and cost-effectiveness, its efficiency is often limited by slow reaction rates and uneven fluid flow distribution. A key underexplored factor contributing to this inefficiency is the complex pore structures within the heap, particularly the influence of intra-particle porosity and fracture evolution on fluid transport and mineral dissolution processes. This thesis explores flow and reactive transport through a series of controlled experiments that combine both engineered and natural porous systems. Engineered dual-porosity particles were designed to replicate critical features of chalcopyrite ores, such as micro-porosity and mineral content. Using advanced image processing and chemical analysis, the impact of intra-particle pore networks on fluid flow was studied. Complementary column leaching experiments on chalcopyrite particles further reveal that intra-pore variations through selective dissolution can affect lixiviant access. To better understand transport dynamics, synchrotron-based imaging was employed to capture real-time changes in fluid distribution and dissolution processes. The resulting time-resolved dataset is processed to generate segmented 3D images distinguishing liquid, solid, and air phase, enabling visualisation of fluid behaviour influenced by intra- and inter-particle pore geometry across different column packings. This resource offers new insights into the links between flow patterns, pore network development, and mineral dissolution.