MINE EXCURSION
SHAFT SINKING
AT THE NEXT LEVEL
Master Drilling unveiled its new shaft borer on a farm near Fochville in
South Africa last year. The machine is bound to change shaft sinking
forever, writes Leon Louw who visited the drilling site.
B
lind shaft borers have been tested in soft rock
applications in other parts of the world, but to drill a
vertical shaft through norite as hard as 320Mpa, would
be a feat nobody else has even attempted. Koos Jordaan,
executive director and technical director at Master Drilling,
says they chose the site specifically because of its almost
indestructible norite, and excavating, during the initial test
phase, a shaft of only eight to 10m deep would prove that it
is indeed possible to sink a shaft of more than 1 000m deep
and up to 11m in diameter from the surface down, through
extremely hard rock.
When African Mining 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
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African Mining January 2020
The shaft borer’s main objective is to sink a vertical shaft from
surface quicker, safer and cheaper than traditional shaft sinking
methods. Raiseboring a shaft from the bottom up, has become
the most popular method of establishing a vertical shaft in
modern times, and it is the core service Master Drilling offers.
However, it requires capital investment in the form of decline
shafts to get the raiseboring equipment to the bottom of the
intended vertical shaft so that the reamer head can be fitted
onto the drill and work its way up from surface, which means it
takes longer, often at exorbitant costs. On the other hand, the
older, more traditional methods of blasting out a shaft requires a
big workforce and is by nature a costly, dangerous and time-
consuming undertaking. To sink a vertical shaft from surface with
less than a fifth of a traditional crew, at only a fraction of the cost,
in double quick time, makes the blind sink hardly a revolutionary
idea, and if Master Drilling actually pulls it off, it will take shaft
sinking to the next level and is sure to be a game changer.
Master Drilling’s revolutionary shaft borer and vacuum system.
www. africanmining.co.za