Openpit mining and quarry operators are unaware of the benefits of electronic blasting systems and are. therefore, missing out on opportunities to reduce operating costs and increase the efficiency of downstream crushing, screening and milling operations, says explosives specialist Bulk Mining Explosives (BME) Axxis detonator technologies manager Tinus Brits. He adds that opportunities to reduce emissions of carbon dioxide (CO,) the most common of the greenhouse gases (Gi IGs) and a major contributor to global warming are also lost by openpit operators who continue to use older shock tube technologies in preference to electronic initiation systems.
“Perceptions still exist that electronic initiation systems are more complicated and expensive to use than older technologies. Many operators tend to directly compare costs between the two systems. As shock tube systems are cheaper than electronic systems, the assumption is made that the older technology is more cost effective. Drilling and blasting costs in mining operations, such as quarries, are transparent and, therefore, exposed as corporate targets for cost reduction. Drilling and blasting become focus areas for cost cutting and often, unwittingly, operators do more harm than good by taking obvious actions. No real consideration is given to the benefits of increased production and throughput in the crushing, screening and milling operations, where considerable savings can be achieved.” says Brits.
“The benefits of electronic systems are huge” he stresses, adding that openpit operators who have switched to these systems over the last two years have realised considerable operational savings.
Besides the expected benefits of air-blast- and-vibration control produced by electronic systems, other major advantages are enjoyed by operators, BM H notes. “The primary benefit lies in the flexibility of electronic systems like BME’s Axxis systems; one item in the magazine can give any delay required something that is impossible with shock tube,” says Brits. The dramatic difference in accuracy between shock lube and electronic systems is not appreciated, he emphasises. Using the accuracy in a well-designed blast timing plan can dramatically transform operations and allows optimal interaction of the shockwaves between adjacent blastholes to enhance fragmentation, which is not possible with inaccurate initiation systems.
“Programmability of Axxis digital electronic detonators allows varied settings from zero lo 10 000 milliseconds (ms) in 1 ms intervals. Blasts can, therefore, be modified to suit operator needs and the particular geology of an area. Electronic detonators also do not suffer cutoff problems that are common in older initiations systems, and, therefore, allow larger blasts to be fired without the risk of cutoffs and failures.” says Brits.
In addition, two or more blasts can be fired next to each other because electronic initia¬tion systems are impervious to rock from one blast site landing on another site. Two-way communications between the blasting box and detonators mean that problems can be identified before a blast. Misfires can also be prevented, as the system will identify where a possible failure will be and this can be corrected before the blast is fired. With older initiation systems, any damage lo downlines will not be identified and the resulting misfires will only be discovered after muck-pile digging has started, Brits notes.
“To fully realise the potential, electronics companies have to look beyond breaking rock. Finer fragmentation in a quarry blast allows more material to pass through the crusher circuits, thus improving profitability, as more stone moves through the gate. Massive savings can be achieved on electricity costs at the crusher and load and haul rates can be improved. Wear and tear on plant is also reduced. Throughput in tons an hour increases and. as fragmentation is better, the risk of equipment breakdown is reduced.”
The major, often unconsidered, beneficiary of electronic initiation systems is the environment, says Brits. “The manufacture, transport and firing of 1t of explosives will create about 41 of CO,-equivalent GHGs. To load and haul the rock blasted by the 1 t of explosives will produce about 81 of GHGs and to crush and process the same rock will release about another 321 into the atmosphere.”
This article was originally published in the October 2012 issue of Mining Weekly