BURNING FRONT Illustration of a cross-section through a blast showing the sequence of detonator initiation using a shocktube initiation system with typical firing times shown
The popularity of electronic initiation in blasting is bound to grow as more opencast mines and quarries benefit from the reliability and accuracy of these systems and the broader impact of high-quality blasts on their operational bottom line, says specialised mining chemical products and services provider BME.
“The age of electronic detonators is not only making blasting practice more dependable, but is also allowing for larger and more cost-effective blasts,” says BME blasting technology director Tony Rorke.
He notes that the use of shocktube, or nonelectric detonators, has always had been restrained by its reliance on a limited number of delay periods and a limited burning front.
“This places constraints on the blast design and implementation, and can raise the risk of a misfire under certain conditions.”
He says, in a large blast, there is a greater chance that shocktube surface and downlines can be severed by a movement of the ground during a blast, which creates a situation where longer delay periods could become a risk.
“When you blast with shocktube, you will not necessarily know that there has been a misfire until the blasted material is being loaded.”
Rorke says one of the major advantages of using electronic detonators is the ability to fire blasts wirelessly. He says using a master control box to communicate wirelessly with up to ten ‘slave boxes’ makes it possible to easily scale up the size of a blast while controlling it.
“Each slave control box can be hard-wired to up to 600 electronic detonators, making this an increasingly attractive option for mines wanting the added value of larger blasts – [accomodating] up to 6 000 detonations.”
BME can assist an opencast mining client in designing and conducting blasts involving more than 3 000 detonators, which deliver a number of benefits, such as reduced operational downtime and better overall quality of fragmentation, says Rorke.
“While mines may have historically avoided larger blasts because of the higher risk of error, BME has been able to demonstrate that our electronic detonation technology is highly reliable as it is scaled up to suit the customer’s optimal requirements.”
He says the wireless technology also makes it possible to simultaneously initiate blasts in different parts of the pit, or even in adjacent pits, which makes the best use of the operational downtime required when blasting.
The reliability and versatility of electronic detonation has been enhanced by the range of software and hardware advances made in recent years. BME has developed its own digital initiation system, called the AXXIS, which improves safety and promotes ease of use, robustness and accuracy, says Rorke.
He adds that the system allocates precise firing times to the electronic detonators, allowing engineers to design complex firing sequences in a blast to achieve predictable and repeatable blast results.
Rorke says, with its ability to develop software to make the science of blasting ever more precise, BME has also pioneered the BlastMap III computer software program – now in its third generation – with complex equations and useful graphics to help practitioners design the blast they need.
“Used in conjunction with the AXXIS digital initiation system, BlastMap III gives customers the best blast results and assists in making blasting much more efficient. It allows the fine-tuning of blast parameters that include vibration control, fragmentation optimisation, dilution control, heave control and specialised blasting scenarios.”