University of Cambridge

The extraction of minerals by mining consumes large amounts of energy, up to 7% of worldwide consumption. Grinding, crushing, and cutting are particularly wasteful; an enormous amount of energy is spent breaking big rocks into smaller rocks. The development of low-energy techniques to liberate minerals from rock has a major impact on sustainability and global warming, and is necessary for economic competitiveness, tougher environmental regulations, and a continuously growing global energy demand. Material models of rock comminution must be developed to help identify the sequence of loadings that promotes cracking on an appropriate length scale and minimises frictional loss between rock fragments. Current empirical models are based on idealised loading in a given direction and are thereby limited in their applicability to more complex loadings for mineral extraction.

A mechanics-based characterization of rock fragmentation will be facilitated by recent advances in experimental capabilities, computational methods and micromechanical modelling of structural materials. Hence, the overall research objective is the development of a ground-breaking constitutive model for micro-cracked heterogeneous rock. Advanced numerical methods will be employed to develop an appropriate computational framework for addressing case studies across time and length scales. The model will be calibrated by a novel set of rock fracture experiments with cutting-edge instrumentation.

Dr Martínez-Pañeda’s experience in micromechanics of metallic materials will be particularly relevant as the project crosses the boundaries of fracture mechanics, geology, and mechanics of materials. The research methodology will benefit from skills transferability in an interdisciplinary effort to bring the geological and structural materials scientific communities closer together with the aim of repeating previous achievements.

As the project constitutes a major step forward towards understanding, modelling and optimising the mechanical response of brittle materials, its range of applicability is enormous. The model will have a major impact on the mining industry, where there is a strong need to liberate minerals at lower energy costs. Specifically, cracking predictions will be used in rock comminution to determine the minimum energy path by a sequence of loading, guiding machine design and operation.