The method has been outlined in a new report, Ultra-High Intensity Blasting – A New Paradigm in Mining, by a team led by Dr Geoff Brent from Orica.
Finer ore improves efficiency downstream
"By utilising explosive energy in the pit to produce much finer ore we can dramatically increase the efficiency and throughput of the downstream comminution processes of crushing and milling," Dr Brent said.
"The overall energy consumption across the mining and milling cycle can be reduced with a consequent reduction in emissions. This is a step-change in ore processing.
"To date it has not been possible to blast at these ultra-high explosive energies, or powder factors, due to safety and environmental constraints.
"However, the new technique demonstrated for the first time that not only can these ultra-high energies be safely utilised but they can also deliver improved mine productivity and reduce environmental impacts in open pit mines.
"The key to the breakthrough has been to use the rock itself to contain the explosive energy by the selective deployment of state-of-the-art digital electronic initiation systems in novel blast designs.
"The new method was thoroughly tested in blast models and then verified in large scale production blasts.
"This breakthrough approach is particularly important given the worldwide trend of decreasing ore grades.
"More ore needs to be ground and processed in order to achieve production targets and this method has the potential to generate a step change in mine productivity, particularly in complex or lower grade ore bodies.
"It can render ore bodies that might ordinarily be uneconomic both affordable and practical to extract."
Environmental benefits
Dr Brent said: "The potential environmental benefits are also enormous. The technique has the potential to cut CO2 emissions associated with grinding by up to 30 per cent."
Orica Managing Director Ian Smith said the quest to use the chemical energy in explosives to improve ore fragmentation and deliver a step change in mine processing efficiency was a priority for the global resources sector.
"The use of electricity to mill ore is usually the largest consumer of energy on a mine site and ore comminution constitutes a significant percentage of electricity consumed worldwide," Smith said.
"Independent modelling has indicated that increasing the explosive energy by several fold can lead to increases in mill circuit throughput of up to 40 per cent and savings of tens of millions of dollars annually."
The research was recently awarded the 2014 CEEC Medal by the Coalition for Eco-Efficient Comminution (CEEC).
