Mining Mirror May 2018 - Page 27

Mining in focus carbon footprint — and which can also be improved to result in less CO₂ emissions. Research shows that for every cubic metre of rock mined, about 4kg of CO₂ is produced by the explosives, 5kg of CO₂ by the process of loading and hauling, and 27kg of CO₂ by crushing and milling — a total of some 36kg. An important negative result of a bad blast is difficult digging conditions: loaders will struggle to dig where the required fragmentation has not been achieved, for instance. This means the machines will burn more diesel and emit more CO₂ . Coarser fragmentation will also lead to less-efficient functioning of the crushers and the mill, which will in turn consume more electricity — also a major greenhouse gas contributor. By blasting badly, a mine will effectively be losing ore. So, despite creating all these extra greenhouse gases, there is even less ore to show for it. The result is that more mining is necessary to reach the targeted production levels. Therefore, there is plenty of scope for mines to reduce their carbon footprint by improving their blasting performance. It has been shown that throw blasting can cut greenhouse gas emissions by 1–2%, and improved fragmentation can achieve even larger reductions of about 6%. Even greater potential lies in reducing ore losses, with efficient ore-waste separation capable of reducing greenhouse gas output by between 5% and 25%. As mining companies are required to report more thoroughly and systematically on their triple-bottom line — including the environmental impact — they should pay greater attention to their blasting practices. They may be pleasantly surprised by what can be achieved in terms of both reducing greenhouse gases and improving mining efficiencies. b About the author Tony Rorke is technical director at blasting specialist BME.