ON SITE
support. Mesh is applied to the sides of the
shaft and depending on the shaft diameter,
a thick layer of shotcrete.
The platform features a shotcreting
system which applies a layer of shotcrete
as the machine descends further down
the shaft. Kibbles are used to hoist the
concrete used in the shotcrete mix up and
down the shaft. Jordaan says they will
need to hook and unhook about four or five
different kibbles depending on whether
they move people, concrete, equipment
or excavated rock material. “Obviously
there is a lot of intelligence running down
the main stage into the machine, so there
needs to be a proper handling system
for all the hoses, hydraulics, electrics and
communication cables,” explains Jordaan.
The stage platform carries all the
support equipment, including, amongst
others, compressors, high tension power
cables, transformers, agitator tanks,
vacuum pumps and a hydraulic deck.
The hydraulic deck is designed in such a
way that it can be configured for a lower
kilowatt usage and for a range of different
diameters.
Advancing into solid rock
Above the stage is the lifting phase which is
designed and built to retrieve the machine
once the shaft has reached the bottom,
which could be more than 2km deep. The
sheer weight of the machine makes it
unsafe to hoist it to the top, and therefore
the boring machine, support stage and
equipment needs to be dismantled and
lifted out of the shaft in separate pieces. A
sturdy headgear which is easy to remove
will be used to hoist the machine back to
surface. The entire system at the Master
Drilling site was run off a 400 Volt generator
with a transformer that converts the power
to 525 Volts.
When the group visited the test site, the
machine was advancing at a rate of more
than 500mm per hour, however, Jordaan
says they are hoping to optimise and
improve the penetration rate to more than
650mm an hour. He further explains that the
gravel-sized fragments of the rock cuttings
indicate the efficiency of the machine.
“Cuttings should not be fine-grained sand.
Big fragments are a good indication that
the cutter head is operating quite efficiently.
Banana shaped chips, which we normally
get with our Tunnel Borer, is a good sign,”
says Jordaan.
In a rapidly changing world, where
mechanisation is no longer just blue sky
thinking, the shaft borer is leading the pack
into new frontiers. Using the machine to
sink a shaft will not only be a lot faster
than conventional methods, it will also be
safer, and it will reduce the overall costs
significantly. Jordaan says that only 20% of
the personnel needed on a conventional sink
are deployed when drilling with the shaft
borer. Moreover, only 50% of the power is
needed. The estimated cost of the entire
system will be in the region of R500-million.
Although there has not been interest
from prospective buyers yet, Jordaan
explains that they will be targeting certain
regions in the world where there has been
an increase in mining activity, Russia and
Kazakhstan being the most prominent.
“Through our global distribution and
business network we are aware of where
shafts will be sunk, the geology in those
areas and how they will be constructed. At
the same time, we are still in the process of
testing the machine and we’ve invited several
groups and potential clients from around the
world to come and see what we are doing,”
says Jordaan. He adds that once an order has
been received, the system could be up and
running within a about 12 months.
When the group left site, the machine
was still grinding away steadily, leaving
behind stockpiles of norite fragments in the
hot summer sun. Other than the growing
piles of rock, a massive black steel frame,
a generator and vacuum system, there
was absolutely no sign that underneath
our feet a perfect shaft was being sunk,
with almost no effort, no blast, no noise, no
dust and with a workforce of only six – an
extraordinary feat.
The drilling team on site, from left: Klint Somerset
(Electrician), Pedro Mucale (Assistant), Nicol Goodwin
(Project Engineer), Walter Tshabalala (Fitter), Lukas
Muller (Site Manager), Gordon Brandon (Fitter).
www.equipmentandhire.co.za
JANUARY/FEBRUARY 2020
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