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

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.

The primary beneficiaries are industrial explosive manufacturers and mining companies. These sectors will benefit economically from reduced costs and increased efficiencies as a result of having, for the first time, a predictive non-ideal detonation physics modelling tool and service. Explosive manufacturers will directly benefit by application to product support, provision of marketing data and from reduction of the significant costs of experimental testing, in particular during product development. Mining companies will benefit by having a predictive tool providing the output of the detonation element of the mining process, which can in turn be fed into blast design models for a scientific approach to blast optimisation. They will also benefit from the modelling service by being able to verify claims of explosive manufacturers, compare and contrast products on the market and decide best choice for application. The sector as a whole will benefit by the provision of a global standard for characterising non-ideal explosive performance.
The UK will in particular benefit by the generation of wealth from external sources, since most of the income from the commercialisation will originate from overseas where the major mining operations and supporting explosives manufacturing mainly occur. This project will provide a means by which the UK economy can tap into these large and extremely lucrative markets and draw some of the economic benefit to the UK through inward investment in the technology being developed at the University of Leeds.
One of the activities which will result from this project being funded is the provision of training to end user companies in the use of detonation software and the science behind it. This will provide professional development benefits to those employees who receive the training. This will also result in an 'up-skilling' of certain sections of the mining workforce, providing benefits to the employers as well as the individuals involved. This will in turn help the industry move towards their desired position of a more scientific approach to blast design. Indeed, by enabling such an approach the project will impact on the significant potential to increase efficiency as well as profitability of metal ore extraction. This has broader impacts both economically and across society. The cost of metals has increased enormously in recent years due largely to increasing demand from developing economies. The production of larger quantities of useable ore for the same amount of effort and consumed ore body ought to help reduce metal prices (or at least go some way to stemming their rate of increase). This would provide both economic and societal benefit to developing economies where high prices of commodities such as metals may stifle growth. In developed countries high cost of metals also has an economic impact on a number of industries most notably construction and has also led to an ever increasing problem of metal thefts.
While mining is the initial target market, UK society will also be able to benefit by application of the technology to the UK defence and security sector. Improvised explosive devices used by insurgents abroad and for extremist terrorist activity at home also tend to have non-ideal detonation properties similar to industrial explosives. The project would enhance the UK defence sectors ability to characterise these explosive and hence to assess the viability of devices and to predict and mitigate against their potential to damage to our civilians, armed forces and infrastructure.
Further beneficiaries are also envisaged via diversification by application and adaption of the technology for other explosives utilising industries. These include demolition and potentially for enhancing oil and gas exploration and extraction, e.g. perforation charge applications. Impacts of the latter would be increased energy security and maximising finite resources