ROCK REINFORCEMENT
test at the LKAB Malmberget underground
mining operation. The field test ran from early
May to late August 2018, with operators working
with the machine during day shifts. The results
achieved during this time was found to be very
positive. Productivity was improved by 64%
compared to existing cement grout-equipped
bolting machines, which was viewed as an
acceptable result by the LKAB project team.
“Considering that this outcome was achieved
during a field test where training, bug fixing and
other time delays were factored into the
numbers, the machine operators saw great
potential for improved productivity over time.”
A major advantage of the new system was the
ease of use and minimal cleaning time needed
during operation. Cement grout machines require
regular cleaning of the machine during operation
in order to prevent the cement grout from
sticking to the machine and clogging machine
functions. In contrast, the resin machine required
minimal cleaning. At the end of shift, the
operator could simply turn off the power and
water to the machine and walk away. In fact, the
machine stood for four weeks during the
Swedish vacation period with no steps taken
beyond flushing the water system on the
machine. “I’ve spent the last five years on this,
and I dare say it’s a huge success. It’s a crucial
step forward in rock bolting technology,” says
Johnsson.
During the field test, extension drilling with
SDA bolts was also tested, with drilling depths
up to 15 m depth proven to be feasible with resin
pumping. This additional capability has the
potential to replace traditional cable bolting in
areas where rock conditions are especially poor.
This adds yet more functionally options to the
Boltec.
The SDA and pumpable resin system can be
combined with several other bolt types on the
Boltec machine. This means that users of the
machine are able to install the bolt to suit the
rock reinforcement demands specified by the
geotechnical engineer.
“An important factor to achieve a workable
rock reinforcement solution is to have a system
where the bolt design, bonding agent and bolting
rig all work together to provide a robust and
reliable bolt installation”, says Peter Bray, Global
Product Manager, Epiroc. “To this end, Epiroc has
worked hand in hand with a leading bolt and
chemical supplier to create a bolting system that
addressed the issues faced with long term
bolting in poor ground conditions”, continues
Bray.
The integrated pumpable resin system from
Epiroc is designed to be used on the mechanised
bolting machines Boltec M and Boltec E models.
However, work is also advanced on testing of a
fully autonomous version of Boltec for the new
22 International Mining | AUGUST 2019
SDA rock bolting system.
Elsewhere, the MEYCO ME3 concrete sprayer
from Epiroc has been equipped with upgrades
and new options “to make it even greater.” The
improvements made to this leading concrete
sprayer will increase productivity and safety, and
lower total cost of ownership.
“These improvements will lift concrete
spraying to an even higher level” says Brandi
Kossub, Global Product Manager at Epiroc.
Besides updates to increase the constant flow of
concrete and less pulsation, the new boom base,
or turret, makes it more robust, durable and
longer lasting. Now, the MEYCO family has even
more commonalities with each other.
Equipped with Epiroc’s telematics system
Certiq, vital equipment information in support of
the operation. “We work closely with our
customers. We talk to people on site to ascertain
what they really need and want in the machines,”
relates Kossub. “Our hands-on experience makes
all the difference.”
MacLean face bolting solution for
deep mines
MacLean Engineering has developed a face
bolting option for their flagship 975 Scissor
Bolter in order to address the challenges posed
by higher ground stress as mines continue to go
deeper. The company states: “With more mines
adding the step of bolting the face to their
development cycle, the 975’s face bolting
capability extends its top-tier safety and
productivity to the face.”
MacLean Engineering’s solution to face bolting
follows the MacLean philosophy that it says has
been vital to the success of its bolters and other
support equipment: “provide a way for miners to
do their jobs with first-rate safety and
productivity. With this objective in mind and,
knowing that the most significant issue with face
bolting was the movement of different equipment
in and out of the heading, a key part of
MacLean’s solution was the ability to carry out
the entire process with one machine. This means
no more time wasted waiting for equipment to
become available and, no more tying up
equipment that could be productively used
elsewhere.” Equipped with the face bolting
option, the MacLean 975 Scissor Bolter can
scale, bolt and screen the walls and back; wash
and scale the face; and, bolt and screen the face.
Trials at a number of Canadian mines have
helped refine the face bolting feature. In the
most recent trial, which involved putting split set
bolts into 5 x 5 m faces, the bolter was
consistently scaling, bolting and screening faces
in less than two hours. “At faces that didn’t
require a lot of scaling, the time to do all this was
reduced even further. The efficiency of this
method was obvious: changing the bolting deck
from regular bolting mode to face bolting mode
took less than five minutes and eliminated the
much lengthier process of moving equipment in
and out of the heading. Customer feedback
indicated that there is a lot of value in being able
to do it all with one machine and the results were
tangible – they were gaining extra rounds. The
trials confirmed success in applying the
productivity and safety of the MacLean bolter to
the face.”
MacLean believes that face bolting on the 975
Scissor Bolter answers the call for a more
efficient way to provide a safer environment for
miners working at the face. “As more mines
expand deeper or into higher ground-stress
environments, this will be an increasingly critical
feature.”
Geobrugg addresses underground
mesh installation
Due to seismicity and the blasting process,
rockburst damage is a growing risk in
underground excavations around the world.
Traditional support and reinforcement systems
as for example shotcrete reinforced with electro-
welded mesh or fibercrete used in underground
mining are limited in their capability against
dynamic loads. The development of diamond-
shaped lightweight steel wire meshes of very
high strength in recent years has offered
alternate design solutions. Therefore, Codelco’s
El Teniente mine, the largest underground mine
in the world and the Swiss company Geobrugg,
carried out full-scale dynamic tests.
In underground tests, a dropping barrel filled
with steel and concrete simulates mine rockburst
energy effects on the Geobrugg high-tensile
chain-link mesh
The design consists of high-tensile steel wire
mesh, anchors and shotcrete. The full-scale test
was carried out in Walenstadt, Switzerland which
is designed to generate a dynamic impact of 60
kJ on a ground support as used at El Teniente
copper mine in Chile. Because of the use of high-
tensile steel wire (min. 1,770 MPa) and the
flexibility of the chain-link mesh, such a support
system can be applied in areas with very high
static and dynamic stress.