HIGH PROFILE
different mining methods such as the ability to
change the diameter of the tunnel, curve radius and
inclinations as well as geological conditions. The
equipment is modular in configuration which
increases the mobility and reduces complexity of
design and maintenance.
Flexible
tunnelling in mines
Paul Moore spoke to Koos Jordaan, Master Drilling
Executive Director, about its state of the art and modular
Mobile Tunnel Boring (MTB) solution, which offers an
efficient, cost-effective and flexible alternative to existing
mining and tunnelling methods
PM: Can you summarise why the MTB is a game
changer versus other related technologies?
or hanging wall/roof. The increased productivity,
con tinuous operation, less manpower, proven
consumable usage, and flexibility utilisation
KJ: The system has the potential of exponential
offsets mechanised complexity for a cost
production rates giving mining owners the ability
competitive alternative to existing mining &
to access underground orebodies faster and with
tunnelling practices.
higher returns. It allows for continuous operation,
Quality excavations are produced without
full face cutting, with simultaneous rock support
explosives induced fractures and damage to the
and material handling. Safety remains paramount
surrounding rock, therefore reducing support
for any project Master Drilling is a part of, with a
requirements. The round profile tunnel provides a
non-explosive continuous operation where the
structural superior geometry to that of a
crew will not be exposed to an unsupported face
conventional drill & blast tunnel. The invert of the
tunnel is filled with less
than 5% of the excavated
volume to provide for a
flat driving surface. The
standard size excavation
provides for standard
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Master Drilling
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50 International Mining | MAY 2018
PM: What are the limits of the machine in diameter
and hardness of rock terms?
KJ: The current configuration allows for a common
backup system, used with a 4.5 m diameter cutter
head/shield/starting frame for contact tunnels and
a 5.5 m diameter set for access tunnels. The cutter
heads are designed for in excess of 300 MPa
hardness of rock but at reduced production and
increased consumable cost.
PM: Key reasons for failure of similar machines in
the past have been inability to cope with material
variability eg lenses of highly abrasive or clay rich
rock; plus lack of flexibility; and high operating
cost versus drill and blast; as well as muck removal
not keeping up with the machine. How has the
MTB addressed these areas?
KJ: The design of the MTB machine allows for
various conditions, with a full-face cutter head
continuously supporting the cutting face through
varying rock conditions. The cutters, their
mounting and positioning is based on proven
technology and cost for different conditions.
The machine consists of 3 to 4 track mounted
backup units controlled by remote control,
powered by diesel-powered hydraulic motivators.
The segmented cutter head/shields/starter frames
are moved by wheel loader and manipulator. This
modular approach provides the necessary
flexibility for movement and customisation for
various conditions. We anticipate the MTB to be
cost competitive vs conventional drill and blast
methods because of the correct application,
versatility and productivity. The 5.5 m diameter