Explosives and blasting technology company BME’s establishment of a high-tech services unit will enable it to advance the use of drones in mine blasting activities.
Drones fitted with high-resolution cameras, guided by computer systems and using the global positioning system (GPS), can provide survey data that has proved “invaluable in improving blast quality”, says BME technical director Tony Rorke.
“Our dedicated team applies a range of modern technologies like drones to help us plan, monitor and execute blasts in ways that enhance clients’ results,” he says, adding that the downstream impact is evident in a range of benefits to mining productivity, such as finer fragmentation, higher digging rates and reduced power consumption in mine crusher circuits.
While great strides have been made in surveying and drilling blast holes, Rorke says, a mine’s survey plan is often not completely accurate or up to date, thereby potentially reducing blast quality.
Using drones enables BME to generate high-quality aerial imagery of the blast site after holes have been drilled, capturing the exact GPS coordinates of each hole, says Rorke. “The position of each hole is surveyed and then marked so that it is easily identified in the footage from the drone as it passes overhead.”
The actual blast-hole positions can then be referenced exactly to the survey coordinates of the mine, thereby allowing for accurate measurement of the variables necessary to plan a blast. The coordinates are exported into BME’s blast timing design program, BlastMap III, and into its Axxis electronic detonator system so that the appropriate firing sequences, timing and charge distributions can be applied to the blast, based on the exact positioning of each hole.
He emphasises the benefits of being able to adjust the timing of a detonation in a blast hole, as well as firing sequences and charge distribution, to take into account any slight divergence of a hole’s actual position, compared with its position on the survey plan.
“Unless we measure, we are only guessing; so, better measurement – before, during and after a blast – is the key to enhancing blast results,” says Rorke, adding that drones advance BME’s measuring ability greatly when combined with its other innovative in-house tools.
The versatility of a drone – as a vehicle for the camera – also extends to valuable monitoring functions during and after the blast. Rorke says experts can use the images and graphics obtained through a drone to gain a clearer understanding of what block faces look like, and whether drilling has resulted in any damage or potential problems.
“Sampling, measuring and quantifying the fragmentation achieved by a blast are much easier . . . from an aerial-scale image that a drone can deliver, making the analysis much more useful in improving future blasts.”
The distribution and volumes of fragment sizes are important to monitor, as they are vital to continuous improvement strategies – after a blast, aerial images provide a much clearer picture of where coarser and finer fragments are located, and the relative quantities.
Further, software allows for the creation of a three-dimensional surface of the blast block by combining aerial imagery and face-profile footage from land-based cameras.
Rorke suggests that it could even be possible to use aerial images as a basis for actually measuring fragment size more scientifically. “We currently take postblast photographs, but it is difficult to interpret these in a way that is statistically valid.”