EXPLOSIVES & BLASTING
EPC Groupe devised a fully automated remote
control up-hole pumping system that comprised
an automated crane arm and a specially
designed hose pushing system to solve the
complex blasting requirements of Mandalay’s
Björkdal gold mine, in Sweden
Chris Barlow, Operations Manager at EPC-UK’s
Rough Close Works operation, said: “Not only is
it (the plant) allowing us to ensure stringent
safety standards are adhered to, it is also
enabling us to create a manufacturing process
that is more efficient in terms of energy usage,
reducing the company’s carbon footprint and
production costs, whilst having the flexibility to
vary production rates.”
Over in Sweden at the Björkdal gold mine, EPC
Groupe has faced an altogether different task to
building a new bulk emulsion facility.
Owned and managed by Mandalay Resources
Corp, Björkdal is around 28 km northwest of
Skellefteå, itself near the historic Boliden mining
district.
The mine, which uses 60 t/mth of emulsion,
produces 800,000 t/y of gold-bearing ore from a
combined open pit and underground operation.
Around 60% of this feed comes from
underground.
Mineralisation at the mine is typified by gold-
quartz hosted veins, which are vertical to sub-
vertical and strike between 40-55°. These veins
vary in width between a few centimetres to over
two metres, with the veining locally complex,
with many cross-cutting thin veins.
“This unique geology, with its constantly
changing drifts combined with the harsh climatic
conditions of northern Sweden, make mining the
area a continuous challenge,” EPC Groupe said.
“Since the mine opened, its operators have
continually looked at ways to improve the
42 International Mining | AUGUST 2019
effectiveness and precision of their blasting
processes and have explored ways to create an
even safer working environment for
employees.”
To meet these objectives, the gold mine
approached EPC Groupe, back in 2013, to solve
its blasting issues.
Björkdal uses the long hole stoping blasting
method – a technique considered highly selective
and productive – however this selection
presented a number of challenges: first, the
vertical nature of the mine’s holes created a need
to provide an explosive that would remain
stationary during the blasting process and,
secondly, 30 m up-hole charging needed to be
maintained, in addition to standard horizontal
hole charging, during a continuous mining
process.
EPC Groupe said it, first, addressed the need
for a tailored emulsion formula, looking at the
thickness and density required for the explosive
to stick reliably in the holes. This led to the
creation of an explosive blend with an extremely
high viscosity level that could adhere effectively
to the side of the vertical holes, the company
said.
To tackle the issue of maintaining 30 m up-
hole charging during a continuous mining
process, the EPC team researched several
solutions, settling on a fully automated remote
control up-hole pumping system that comprised
an automated crane arm and a specially
designed hose pushing system. Both were
remotely controlled and linked to a PLC.
“The result provided a clear and visible PLC
control of the hydraulic functions, which made
calibration easier and provided an accurate feed
and smart retraction for the charging hose,” EPC
said. “Additionally, by adding a probe to the end
of the hose, the system could also be used for
borehole deviation measurement and provide
precise information to help remove potential
uncertainties during a blast.”
During the transition, the penetration depth of
the holes created was constantly measured,
allowing operators to customise charging on a
hole-by-hole basis. “Although not new to the
industry, the use of this hole depth measurement
technology in mining underground stopes is
unusual, but it is being used with great success
at Björkdal,” EPC said.
Alongside the automated crane arm and
specially designed hose pushing system, the
technicians at EPC developed a detonator box
able to directly integrate into the system and
compartments according to different delays.
“This enables operators to save precious time
during charging operations,” the company
said.
“As well as improving blast precision and
effectiveness, the newly developed technology
has also helped to enhance safety for operators,”
EPC said. “As it is remotely controlled and linked
to a PLC, operators can easily pilot the movement
of the crane arm and insert the hose into
different boreholes in a very flexible way. The
technology also negates the need for operators
to stand directly underneath the holes. They can
now position themselves clear of the blasting
location, which provides a global view of the drift
ceiling and makes the entire process much
safer.”
Underpinning the new up-hole pumping
system was EPC Groupe’s EXPERTIR blasting
software. EXPERTIR allows the integration of 3D
profiles from the likes of laser, drone, or digital
photogrammetry, using this geometrical data to
model holes, including tilt and depth, so that
drilling can be completed accurately.
The company said: “EPC worked closely with
the operators of Björkdal gold mine to create a
specific version of EXPERTIR that would address
the mine’s particular needs. The result is
EXPERTIR UG (Under Ground) – a software
program that allows an operator to create a full
3D model of the drift being blasted and to assess
key performance indicators, such as contour
quality.
“Millions of points are taken into
consideration using a 3D laser or
photogrammetry method, to provide precise and
comprehensive results. Moreover, the software
allows the user to process borehole deviation
data and see a 3D model of the drilling and
blasting geology.”
EXPERTIR UG has now been integrated into
Björkdal’s existing applications, which include
GPS-based devices that track details such as
muck pile movement and ore dilution, to create
an “entirely transparent, cohesive system”. IM