In-situ study of mineral liberation at the onset of fragmentation of a copper ore using X-ray micro-computed tomography

A better understanding of the relation between ore fragmentation and ore texture is a key to the energy efficient extraction of targeted minerals from low grade ore deposits. In this study, X-ray micro-computed tomography is employed to study mineral liberation during the tensile failure and onset of fragmentation of a copper ore. We present the results of experiments based on a high-pressure instrument enabling micro-mechanical studies to be carried out in-situ (inside a micro-CT scanner). This experimental platform enables mapping in 3D of the evolution of a sample of copper ore during an in-situ fragmentation test. The fragmentation occurs quasi-statically via tensile-activated nucleation and growth of multiple cracks producing a complex fracture network. Coupling breakage with microstructural information, we determine quantitatively the impact of ore textural features on fracture patterns and mineral liberation. This information can be compared to the ore mechanical behaviour, in particular to measurements of the deformation energy, the strain deformation field or the stress relaxation response. The copper liberation, fragment size distribution and breakage patterns are statistically characterised and related to two dominant comminution mechanisms which are clearly identified in the sequence of tomographic images. Our results show that in-situ micro-CT experiments could inform new studies of ore fragmentation at the laboratory scale and may offer new avenues to address current challenges in the design of efficient comminution processes.