Predicting Detonation Characteristics and Performance of Commercial Explosives for the Mining and Explosive Manufacturing Industries

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Industrial explosives, such as ammonium nitrate-based commercial products, are used extensively within the mining and quarrying industries to fragment rock to either allow its removal giving access to the target mineral or to break up mineral-bearing rock for processing. Optimization of the blasting process is key to minimizing hazard, environmental damage and costs. Factors affecting the outcome include choice of explosive (solid/liquid, formulation, additives, density), charge (borehole) diameter, charge loading/borehole depth, initiating system, borehole layout and density, detonation timings. The design significantly impacts on costs of downstream operations, e.g. unwanted production of oversize boulders which are costly to mill or material too fine to handle easily, the transport from the blast site of rock and to the site of explosive, drilling costs and time between blasts and rock transfer operations. At the same time, minimisation of the associated hazards and environmental impacts, under increasingly restrictive legislation, is paramount. A failed blast results in doubling of costs at the minimum to a mine closure representing a loss of millions of dollars. Hence there is a significant need and market in the mining sector for any method which can help to optimise blasting processes.In these commercial explosive, the detonation process occurs at speeds of kilometres per second and produces pressures of several gigaPascals - it is this enormous power which is harnessed to shatter rock in blasting operations. However, the detonation processes in commercial explosives is "highly non-ideal" in that the propagation of the wave is determined by the strong coupling between multi-dimensional effects and chemical kinetics, leading to very significant departures from "ideal" behaviour predicted by assuming instantaneous reaction. These explosives have reaction zones of several millimetres, resulting in critical diameters of several centimetres or more. This is the size of explosive below which it does not detonate - knowledge of this is vital to ensure both the integrity of the blast and for safety. The non-ideal behaviour of these explosives and the resulting very strong feedback between detonation speed and pressure, borehole diameter, the rock type and its movement and breakage, makes prediction of the process extremely challenging and no satisfactory method existed before the breakthrough research resulting from the sustained EPSRC funding for this research area. This has culminated in a novel "Variational Streamline Approach" to the problem developed via EP/F006004/01 which solves the problem to arbitrary accuracy while being extremely computationally cheap allowing very large parametric studies to be performed.The purpose of the Follow On Fund proposal is take to the academic research codes and techniques developed via the prior EPSRC project, apply them quantitaively to commercial explosives and rock blasting and produce a commercial suite of non-ideal detonation physics software tools which can be exploited by the explosive manufacturing and mining industries to optimise blast design.