Screens & Feeders

Blasting breakthrough could benefit quarries

The 2014 Coalition for Eco-Efficient Comminution Medal was recently awarded to Orica senior research associate Dr Geoff Brent and his research team for their paper Ultra-high intensity blasting – A new paradigm in mining, which explores a new blasting technique that involves increasing explosive energy.

“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,” Brent explained. “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.”

Orica managing director Ian Smith said that ore milling was “usually the largest consumer of energy on a mine site” said that the new technique could lead to increases in mill circuit throughput of up to 40 per cent, thus savings of tens of millions of dollars annually.

The new technique could also help reduce environmental impacts in open pit mines. “The potential environmental benefits are also enormous,” Brent stated. “The technique has the potential to cut carbon dioxide emissions associated with grinding by up to 30 per cent.”

New breakthrough
Brent said that while it had not previously been possible to blast at these ultra-high explosive energies – or powder factors – due to safety and environmental constraints, the team was able to make a breakthrough with the use of novel blast designs.

“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,” Brent explained.

“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.”

Although he acknowledged that quarry operators generally don’t want too many fines, Brent said the method might also be applicable to certain quarries looking to increase the extent of their fragmentation.

“One spin-off of the method is better vibration and dust control, which are big issues for most quarries,” he added. “When used specifically for vibration and dust control, lower powder factors may be used.”

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