Reducing energy consumption in comminution by doing much less of it!

摘要

Almost since time immemorial, seekers after metal have picked out attractive pieces from low grade ores and thrown away the obviously barren pieces from high grade ore. As long ago as Agricola, metal seekers have been advised to “husband the fines” as they will almost always be of higher grade. Since the Stone Age, man has had ever increasing access to energy and water at ever decreasing cost in real terms. This process accelerated from the start of the Industrial Revolution and this process has continued until very recently. With the Age of Discovery, metal seekers gained access to ever more mineral deposits. These often replaced age-old and worked out deposits in Europe. In the 21st Century, we face an almost perfect storm of challenge and opportunity. Both energy and water have begun to become more expensive in real terms and access to minerals and especially to water where there is competition from growing populations - are becoming limiting factors. Apart from the more inaccessible corners of the planet - although not necessarily under the oceans - new deposits are ever harder to find and existing ones become lower in grade with exploitation.In contrast to this bleak picture, we now have access to an ever expanding range of sensors. Some of these can detect minerals of interest through meters of rock. Ever more powerful computers are well suited to rapid identification of particles of interest although our ability to keep them lags our ability to detect them. Modern laboratory equipment such as micro Cone Beam Tomography is coming into its own for three dimensional characterisation of ore texture. In many cases, these textures offer opportunities to substantially reduce comminution energy. In terms of generation of opportunities for physical separation i.e. comminution in all of its forms, our use of energy and water has always been profligate. This is unsurprising as those resources have often seemed to be limitless and of negligible cost. This paper considers opportunities for reducing the use of energy in comminution by doing as little of it as possible by using physical separation over a wide range of sizes. These ideas also lead to strategies which might reduce water use and even to what might constitute a mineral deposit.In short, the most attractive way to reduce energy use in comminution is to do as little of it as possible.