Modern Quarrying April-May 2017

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April - May 2017 MODERN QUARRYING 37
EQUIPMENT, SUPPLIERS
& SERVICES
Advancing blast design with drones
Aerial view from a camera mounted to a small UAV clearly showing the
hole positions in the drill pattern.
Explosives and blasting technology leader BME has established a
High-Tech Services unit to advance the application of drones in
mine blasting activities.
According to BME technical director Tony Rorke, drones fitted
with high-resolution cameras and guided by computer systems
using global positioning system (GPS) survey data have proved
invaluable in improving blast quality. “Our dedicated team
applies a range of modern technologies like drones to help us
plan, monitor and execute blasts in ways that optimise our cli-
ents’ results. The downstream impact can be felt 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
blastholes, a mine’s survey plan is often not completely accurate
or up to date – potentially reducing blast quality.
“Using drones, we can generate high-quality aerial imagery
of the blast site after holes have been drilled, capturing the exact
GPS coordinates of each hole,” Rorke says. “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 – to allow accurate
measurement of the variables necessary to plan an optimal blast.
“The coordinates are exported into our blast timing design
program BlastMap III and into our AXXIS electronic detonator sys-
tem – so that the appropriate firing sequences, timing and charge
distributions can be applied to the blast, based on the exact posi-
tioning of each hole,” Rorke explains.
He emphasises the benefits in being able to adjust the timing
of a detonation in a blasthole – as well as firing sequences and
charge distribution – to take account of any slight divergence of
a hole’s actual position compared with its place on the survey
plan. “Unless we measure, we are only guessing; so better mea-
surement – both before, during and after a blast – is the key to
optimising blast results. Drones advance our measuring ability
greatly when combined with BME’s other innovative in-house
tools like our blast planning software together with our elec-
tronic detonator system.”
“Unless we measure, we are only guessing; so better mea-
surement – both before, during and after a blast – is the key to
optimising blast results,”he says.“Drones advance our measuring
ability greatly when combined with BME’s other innovative
in-house tools like our blast planning software together with our
electronic detonator system.”
The versatility of a drone as a vehicle for the camera also
extends to valuable monitoring functions during and after the
blast. What experts can take from the images and graphics is a
clearer understanding of what block faces look like, and whether
there is any damage or potential problems resulting from the
drilling.
“Sampling, measuring and quantifying the fragmentation
achieved by a blast is much easier when done 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 these are vital to
continuous improvement strategies.”
After a blast, drone images from above give a much clearer
picture of where coarser and finer fragments are lying – and
in what relative quantities. It may even be possible to use the
images as a basis for actually measuring fragment size in a more
scientific way,” Rorke adds. “We currently take post-blast photo-
graphs but it is difficult to interpret these in a way that is statis-
tically valid.”
Software now also allows the creation of a three-dimensional
surface of the blast block, by combining the aerial drone imagery
and the face profile footage from land-based cameras.