Although electric detonators have served the industry well for decades, it may be time to let technology take its course. Electronic detonators have been marketed in North America for more than six years by companies boasting heightened safety and higher throughput. And now, after some nudging from the explosives industry, the Mine Safety and Health Administration has stamped its seal of approval on two specific products: the Daveytronic digital blasting system and I-kon digital energy controlled system.

MSHA has recognized that both products comply with standards for shunting and circuit testing. Bob Friend, MSHA's administrator for metal and nonmetal, says regulators require electric detonators be shunted to reduce the risk of lightning, radio frequencies or static electricity accidentally triggering detonation.

However, electronic or “digital” detonators have a built-in shunt, eliminating the need to twist leg wires together. And, elaborate digital testing mechanisms in electronic units eliminate the need for circuit testing with a galvanometer.

“With the safeguards built into the electronic detonator, it is a good technology. It works, and I wouldn't be afraid to use it myself,” Friend says. “It is a much more sophisticated system.”

Electric systems are designed with a pyrotechnic fuse train with a delay element that burns at an approximated rate determined by length and composition. Timing accuracy is affected because the burn rate is subject to variation.

Electronic detonator systems, however, have an integrated circuit and capacitor system, which is internally wired to each detonator to separate the leg wires from the base charge. This greatly reduces the risk of misfire, Friend says. Specially designed blast-control units, each unique to brand, controls the detonation firing sequence by transmitting a selectable digital signal that is identified by each wired detonator.

“The real safety advantage to the system with electronics is that we can have total system verifications before we go into a charge-and-fire sequence,” says Robert McClure, manager of North American operations for Advanced Initiation Systems that produces Daveytronic. “What the regulatory people really like is that almost all of your problems are going to be known up front before you fire.”

If a wire is damaged, certain electronic systems, using two-way communication systems, will pinpoint the location, and repairs can be made. Electronic systems also account for all connected detonators. If one were damaged or lost in a hole, the system would notify the blaster to take corrective measures.

This level of safety and operational transparency was previously impossible, I-kon Marketing Director Mike Mackwood says.

Electronic detonators can typically be programmed in either manual or automated modes, although procedures vary according to brand. In manual mode, a blaster goes detonator to detonator and programs the precise firing type. “It empowers the blaster to make all of the changes that he wants, and he can do it on the fly,” McClure says. “There is no need for a laptop. There is no need to exchange files or anything like that.”

Using an automated mode, blast designs are configured on a computer and then uploaded onto the blasting unit. When blasters have very consistent blast designs or the blaster understands the patterns of geology, they often use the automated system. The blaster can consistently plug in the precise blasting times again and again. Daveytronic has a PC card slot, and newer models have an RS32 port to transfer information. I-kon units rely on a logger unit.

Mackwood says it uses the software design program ShotPlus-i to design electronic blasts. With ShotPlus-i, the blaster designs the blast on a PC and downloads the information with a hand-held I-kon logger. Then, at the bench, he hooks up the detonators in the correct sequence.

The logger automatically records detonator identification numbers and assigns the delay times just as fast as he can walk the pattern. An audible signal confirms that each detonator is successfully connected, and any problems are indicated on the logger's LCD screen.

“It can be a very speedy process, and you know that the blast will be exactly as designed on the laptop,” Mackwood says. “That gives the operators great confidence that they are getting exactly the blasts that they wanted.”

Mackwood says the I-kon logger is inherently safe because it cannot generate enough power to activate the detonators. The blaster unit remains disconnected from the line until the operator moves to a point of safety for firing the blast. There, he goes through a series of programming steps that first “wake up” the detonators and checks to see if they are all in line and functioning properly.

Next, a calibration signal is sent to the timing units in each detonator, followed by a full charging of the detonators. The blast is initiated by simultaneously pressing two buttons on the blaster. Mackwood says I-kon's remote blasting technology can fire a shot from as far as 6,100 feet from the blast holes by using coded radio frequencies.

Daveytronic requires a secure-coded firing command to tell the detonator to shoot. The blaster has to physically turn a safety switch to charge and arm the system. Then a window comes up that allows him to press the firing button, while simultaneously holding a safety key.

This gives the blaster control of the shot that can be aborted at anytime, McClure says. And no two blasts will go off simultaneously, which has been a problem with conventional technology that can produce overlap and scatter, even if the holes are separated.

But what is most likely to catch the attention of surface miners is the possibility of increased fragmentation and reduced vibration. This is achieved through hard-wired systems with high-accuracy digital clocks, McClure says. Optimizing the time between blasts greatly increases fragmentation while reducing vibrations that often stir up the neighbors.

Mackwood says quarry owners can now go into areas previous off limits because of proximity to homes and blast with minimal disturbance.

The I-kon system can time adjacent blasts as close as 1 millisecond. The Daveytronic system can reduce timing to as close as 1/10 of a millisecond.

Both manufacturers say the only thing keeping the industry skeptical is the nature of new technology.

“Just like computers, (electronic blasting units) change every 18 months,” Mackwood says. “And no matter what you buy, it is going to be obsolete in a very short period of time.” However, both companies offer regular upgrades for their driving software and the operating systems.

“Electric detonators have done a great job for a lot of years, but now we have a new and better tool,” McClure says.

Since MSHA approved of Daveytronic and I-kon systems, other companies have requested MSHA's technical support division to evaluate other electronic detonator systems. However, MSHA has not publicly recognizes the validity of other programs. Until it does, the agency will evaluate these systems on a case-by-case basis to ensure their compatibility with circuit testing and shunting requirements.