CONTINUOUS CUTTING AND RAPID DEVELOPMENT
specifically for platinum mining, according to
Anglo.
Sandvik, like several companies looking to
take some of the conventional drill and blast
market share, is applying roadheading
technology to achieve improved advance rates
in mining applications.
During the September quarter of 2017,
Barrick Gold’s Turquoise Ridge mine in Nevada,
US, took delivery of its first Sandvik MH620
roadheader. The decision to use this technology
came after it was successfully applied at the
company’s Cortez operation.
The MH620 is an electrically-powered and
crawler-mounted roadheader engineered to
excavate roadways and galleries. The heavy-
duty machine has a powerful transverse
cutterhead mounted on a robust telescopic
boom and is designed to excavate rock with high
compressive strengths (exceeding 120 MPa).
Weighing 125 t, the Sandvik MH620 cutting
the Range Front declines at Cortez is one of the
world’s largest roadheaders. A 300 kW cutting
motor drives twin rotating cutterheads that are
manoeuvred by a large hydraulically-operated
boom.
Another raiseboring innovation is in proof-of-
concept phase at one of Anglo’s operations in
South Africa.
Epiroc’s Slot Borer is based on proven
technology but destined to drill a narrow vein
hard-rock orebody of just 1-1.5 m.
The cutting system deploys the TBM-style
steel discs in a compression cutting mode. It
consists of a cutting/drilling machine and a
pneumatic conveying system to remove the
cuttings and transport them to the conveyor
belt.
The Sweden-based OEM has also been
advancing the development of its larger hard-
rock cutting models.
While Its Mobile Miner 55V, now owned by
Sweden-based contractor Bergteamet AB, is
awaiting a new trial, Lyly is confident it will soon
be back in the field.
“There is a lot of interest from mining
companies that want to take this machine.
Hopefully we will see it at a mine site at some
point during 2019,” he told IM.
The Mobile Miner 55V is designed for
mechanical excavation and has been developed
for deep mine infrastructure. It can continuously
create reinforced tunnels with a size of 5.5 m x
5.5 m, down to a radius of 65 m with a flat floor.
Epiroc’s Mobile Miner 40V already has a
commercial installation in its sights.
Lyly told IM that a machine destined for Hecla
Mining and the Lucky Friday silver-lead-zinc mine
in Idaho, US, was currently being manufactured.
This machine is typically used in small- to
medium-sized tunnels when an excavation
around 4 m x 4 m in size is required. V indicates
the cutterhead is placed vertically as opposed
to the H for horizontal on the Mobile Miner 22H.
The advance rate of the Mobile Miner 40V is 10-
15 m/day depending on rock type.
The machine is expected to start trials in
Epiroc’s test mine in Örebro, Sweden, by the end
of April and then, after dismantling, shipping
and underground set up, should start
production trials at Lucky Friday in the first
three months of 2020.
In a conference call on its recent September
quarter results, Hecla President and CEO
Phillips Baker explained how the company
envisaged getting the machine underground at
Lucky Friday: “It’s about a six-month process to
get it fully underground and then there’s some
development that also has to be done to have a
place to be reassembled underground.” The
machine will enter the mine via the Silver Shaft,
an 18 ft (5.5 m) diameter, concrete-lined shaft
sunk to a depth of 6,200 ft. The Mobile Miner
will be assembled for testing on surface then
will proceed underground in 5 ft by 5 ft
compartments.
Hecla plans to use the Mobile Miner 40V
primarily for production purposes to take out
the ore, according to Lyly, with the versatile
technology being a good match for the narrow-
vein orebody the company usually mines by cut-
and-fill.
Lyly said the trials of the Mobile Miners and
input from customers indicated the company
should prioritise the actual rock cutting in future
generations, as opposed to the back-up systems
that may follow the machines.
“This makes it more flexible and suitable for
mining applications,” he said, adding the
company is now looking to develop “smaller
and cleaner” machines.
Matt Daley, Group Head of Mining, for Anglo
American, too, provided IM with the company’s
learnings from a long list of mechanised cutting
trials.
“We’ve learned that technology is not
enough. If rock can be cut rather than blasted,
mining can become continuous and more
productive. However, hard-rock cutting is just
one element in a wider process. The secret is to
have all the parts of the system sufficiently
advanced and integrated,” he said.
“Good cutting techniques, alone, won’t
deliver continuous mining.”
Integration
This point has not been lost on the OEMs.
Master Tunnelling, a subsidiary of South
Africa-based Master Drilling, recently acquired
tunnelling expert Seli Technologies as part of a
49:51 joint venture agreement with leading
Italian construction company Ghella SpA.
The two are now intent on pushing forward
with the development of its new Mobile Tunnel
Borer (MTB) concept, both in mining and the
smaller-scope civil construction industry.
Master Tunnelling has, so far, manufactured
one prototype that has been commissioned in a
soft-rock quarry just outside of Rome, Italy. The
exercise proved to be very fruitful, Koos Jordaan,
Executive Director of Master Drilling, told IM.
“We initially anticipated cutting an estimated
30 m advance. After some 10 meters of cutting,
of which the last 6 m were at a 30 m turning
radius, we deemed the test to be sufficient. The
equipment is currently in the process of site
clearance,” he said in mid-November.
“During the commissioning, many aspects
related to the operation of the system were
tested, such as the guidance system, allowing
complex tunnel trajectories as well as the
assembly of the segmented cutterhead by
means of a mobile carrier fitted with an all-
inclusive six degrees of freedom placement.”
This machine has a full-face cutterhead made
up of 17” disc cutters, which are conventional
from a TBM perspective, but are in five separate
pieces. This cutterhead, like the bulk of the 240-
300 t MTB, is designed to be broken down for
transport.
This modularity is geared towards enabling
existing mines with a decline to transport all
equipment into the underground area where it
can then be assembled
The full-face cutterhead – coming in 4.5 m or
5.5 m diameter configurations – is capable of a 1
m continuous advance stroke and can cut rock
in excess of 300 MPa compressive strength. It
can also be controlled remotely by an operator,
reducing exposure to the mining face.
Master Tunnelling is aiming for an advance
rate of 6-9 m/d in 200-250 MPa rock, while the
MTB is equipped with both ground support and
mucking in mind.
Drilling and cable bolting can be carried out
directly behind the cutterhead while the
excavated material is designed to track all the
way through the length of the machine and be
mucked away by a mobile fleet behind the MTB.
While the company is yet to secure a mine
trial for the MTB – it is now in temporary storage
in Europe – Jordaan said the tie-up with Ghella
should provide it with more customer options
down the line.
“Master Drilling’s ambition is to diversify its
service offering through the establishment of a
specialised mechanised tunnelling division called
Master Tunnelling, as well as pursuing smaller
civil tunnelling contracting opportunities, as well
as standard tunnel boring applications in mining
through TunnelPro with Ghella as a partner.
“Through this ambition, we aim to provide
value to the industry through increased
DECEMBER 2018 | International Mining 41