Dyno Nobel has been working on its latest innovation in electronic initiation technology for the past five years. Australian Mining talks to technical specialist Nico Swart to see how DigiShot Plus.4G has done in the wild.
Dyno Nobel is one of the world’s most famous explosives companies; inspired by the groundwork laid out by Swedish namesake Alfred Nobel, Dyno Nobel was originally founded in Norway in 1865 and operates today as a multinational and subsidiary of Australian manufacturer Incitec Pivot.
Recently, the company’s JV DetNet embarked on a project to improve the technology of its electronic initiation systems, the systems that allow the explosives to trigger.
Technical specialist Nico Swart has been working on the company’s DigiShot Plus.4G from concept to creation for roughly five years; the preliminary stages of development actually started in earnest as a multi-tiered process about two to three years ago. Originally from Pretoria, South Africa, and a long-time employee of the company (nearly 14 years), Swart described DigiShot Plus.4G as something of a passion project for the engineering team.
“It’s become like a family base,” he explained to Australian Mining. “We’ve got good relations with the people we work with in our JV.
“They introduced the new system in stages,” he explained. “If you look at the equipment you’ve got the firing system, and the handheld tagger, which is the device you interact with the detonators on the bench.
“The tagger was introduced first, so it focused the developers’ resources on that component and then from there, they developed the actual control equipment that’s used to initiate the blast.”
The new system makes use of a number of forward-thinking systems.
With previous initiation equipment, delays were stored on the firing boxes and were downloaded during the firing process, and if device box failed for some reason, the whole setup process would need to be redone.
Backup devices could help to rectify this issue somewhat, but the new system takes things further; all necessary process data required for initiation is stored within the detonator itself, so should a delay occur, operators can now swap out control equipment very quickly.
“You are ready to go in two minutes,” explained Swart.
The DigiShot Plus.4G system allows operators to connect strings (of detonators), also called firing lines, in any order they like. This is a significant development as traditionally, a unique ID would be assigned to each blast-hole for capture, but since DigiShot Plus.4G knows the hole number, once the location is assigned, the detonator knows where it fits in the blast panel. Dyno Nobel’s proprietary PC-based ViewShot3D blast design software enables timing patterns to be downloaded directly from the PC into the Tagger.
The extensive use of RF synchronisation of the bench commanders in lieu of wired setups is another win for Dyno Nobel. In addition to there being no wires between the firing point and the bench commanders, there is no wiring between the bench commanders themselves with full synchronisation via RF.
“The commanders can be widely separated across the bench as long as there is effective line of sight (LOS) to either the firing point directly or via a repeater commander,” explained David Gribble, manager applications technology at Dyno Nobel, and current director of the DigiShot Plus.4G rollout in Australia. “A lot of systems on the market require the boxes to all be connected up for synchronisation.”
“Instead of running cables between multiple boxes on the bench to link them together, we can just place them on the bench and they all talk to the base commander at the firing position via RF,” added Swart.
“The system limit on timing is stored from zero to 20,000 milliseconds in one-millisecond increments” explained Swart.
“Current electronic detonator systems use an RC oscillator that is temperature dependent, so the current systems available have to physically talk to each detonator and calibrate it to make sure it fires at the desired time.
“With this new system, we’ve also built into the actual detonator the calibration of the RC oscillator that ensures the detonator fires at the desired time so it can now self-calibrate; I don’t have to address each detonator anymore, which removes a lot of time during the firing process. Previously, there was generally a lengthy process in getting the system ready to fire.”
With this reduction in time comes a reduction in on-the-bench training, as well, since some of the necessary processes and information are now stored on the detonator. Individual detonators, strings of detonators or the entire pattern can also be tested prior to connection to the blast commander. DigiShot Plus.4G can also have up to 400 detonators per channel, 1,600 detonators per commander and 16,000 detonators across 10 commanders.
Dyno Nobel’s DigiShot Plus.4G upgrades aren’t confined to the initiation unit and detonator alone; downhole wire too has seen an upgrade, seeing improvements in impact and abrasion resistance, as well as tensile strength. This is a particular point of pride for Gribble.
Like Swart, he comes from a storied technical background — one of his first major projects (now nearly 30 years ago) was the invention of the ANRUB explosive, a low-shock energy explosive designed to slow down the explosive rate of reaction, a feat achieved by replacing the then-standard fuel oil with rubber particles.
Before joining Dyno Nobel as a senior technical consultant, where he has worked for nearly 15 years, he was an employee of Rio Tinto. He explained some of the improvements to the wiring, further increasing system reliability.
“One of the weak points with electronic initiation systems in general is the wires connecting the detonator in the hole to the surface. When you prime the hole, load explosives, and stem the remaining length of the hole with rock, it can sometimes cause a cut in the lead,” he explained. “This is not something you want, naturally — if you cut the lead completely you can’t talk to the detonator, and if you cut it a little bit you might get leakage.
“Together with our JV DetNet, we’ve done a lot of work over the last 2 years to determine what makes good wire and we now understand the factors required in order to make it. Our DigiShot Plus.4G system has rolled out alongside our new wire, colloquially named Black Mamba, and comes in both a standard and premium ‘XTM’ configuration, with XTM wire on spools for lengths of 37 metres and above. This new wire is a real step up compared to our previous wire, we’re seeing great results in the field.”
This wealth of upgraded systems eventually coalesced into a tangible whole just over a year ago, with preliminary trials to prepare DigiShot Plus.4G for market launch having taken place around the beginning of 2017. Following a positive and extensive testing period, the product saw its commercial rollout beginning in the second quarter of 2017. Response from operators, Swart said, has been largely positive. “So much so,” Swart concluded, “that they would never consider going back to the previous system.”
Like his colleague, Gribble is happy with how the launch turned out and how DigiShot Plus.4G has been received, with lead times for product having been cut drastically on account of the company’s investment in local assembly.
“It reduces our supply chain significantly from several months to a few weeks,” he explained.
“We are the only supplier that has local assembly here in Australia, starting from the middle of last year. The majority of our products are locally made which gives us shorter lead times, improves security of supply and the ability to respond more efficiently to customers’ orders.”