WINNING
Clays have different amounts of carbon in, clearly visible in the stockpiles as segregated layers of
white and black clay.
dump trucks depending on the haul load
and the distance, a dozer and a water cart.
Being soft rock, no drilling and blasting
takes place ‒ as clay denotes the finest
fraction of a sediment or soil ‒ nor any
processing of the material at the quarry. It
is simply stockpiled at a storage location.
As quarrying activities have shifted over
the years, that storage space is now in the
quarry itself, though it is regarded as part
of the factory – meaning it falls under the
OSHA rather than the MHSA.
At the stockpile, a dozer is used to level
it, while weather plays its part too. A
typical stockpile would be up to 50 000m3
in size. For safety reasons, it can’t be higher
than about 5m, as the front end loader
reclaims the stockpile from the base and
an overhang would be dangerous.
Shifting pit
The quarry started on the western side of
the site but as one pit is mined out, the
quarry has relentlessly shifted eastwards
and previous pits have been rehabilitated.
The stockpiles are now on that western side
as the quarry has advanced to the eastern
side, and effectively the factory’s storage
area is now the quarry itself, barely 100m
from the plant.
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Another outsourced firm transports the
stockpiled clay to the factory and Von
Wielligh explains that for the first time both
jobs are being done by the same company.
The manpower on the quarry is between
10 and 15 people – none of them employed
by Corobrik. Corobrik Midrand produces
the most diverse range of bricks of any brick
manufacturer in Africa, says Von Wielligh,
and this variety cannot be sourced from a
single quarry. Consequently, 85% of its clay
is imported from other Corobrik quarries
in South Africa, and stored in multiple
stockpiles.
A key aspect of his job is logistics –
ensuring the factory, which runs 24/7 all
year round, never runs out of material, but
also that material is delivered in a managed
fashion to keep the stockpiles as close
as possible to the ‘feeding area’, and not
dangerously high.
Another reason for the high level of
imported material is the fact that the
Olifantsfontein quarry is virtually deplete.
The entire region is known as Clayville,
and all around Corobrik are other quarries
and brick and porcelain manufacturers, but
Von Wielligh explains that after 70 years of
mining there’s not much left.
The most important factor determining
the quality is the iron content of the clay.
QUARRY SA | JULY/AUGUST 2019_17