WINNING
Some clays have a certain amount of
carbon in, in which instance it has to be
closely controlled. It is clearly visible in
the stockpiles as segregated layers of white
and black clay, as well as layers of grey in
between. “For this reason we do selective
mining, and even though we outsource
the mining we have to keep close tabs on
this aspect. Our mining partners typically
pick up considerable expertise in our
specific requirements over the years.
We consequently tend to have a long
relationship with a mining company.
The clay is riddled with carbonaceous
material which has three uses, explains
Von Wielligh: as a source of clay itself, as
a fuel source, and it adds to the aesthetics
of the bricks through the spots it leaves on
the brick after firing. “There has to be a
fairly substantial amount of carbonaceous
material in the product for this to occur.”
Challenges
All the benefication is done at the factory
(just the other side of a fence) and is not
included in mining activity. While the
quarry is small compared to many and
viewed as an adjunct to the factory, it still
requires a Traffic Management Plan under
mining regulations as it is a quarry.
“Having three to four dump trucks is
not a big risk, but we have demarcated
roads as one-way routes to ensure
vehicles never cross each other; while
trucks bringing the imported material
are made aware when mining activity is
taking place.”
Corobrik has its own water truck in
addition to one operated by its mining
contractor, and does regular dust
monitoring at eight points managed by
an outsourced health hygienist. This
ensures dust is within prescribed limits:
“We conform to suburban standards of
less than 300mg a day rather than the
industrial area level of 1 200mg/day.”
The facility uses 1 500kℓ of water a
month, mostly in the factory. Borehole
water is increasingly being used to
reduce the demand on municipal
water. In addition, one of the quarry
pits has filled with rainwater and been
rehabilitated into a dam, which is also
tapped as a water source.
Rehabilitation
A brick factory ideally should be located
in a rural area. However, the result is
that local neighbourhoods typically begin
encroaching over the decades onto the
quarry site. This is not always bad, notes
Von Wielligh, as ultimately the land value
overtakes the value of production, which
would typically be terminated.
“In this area there is a lack of waste
landfill, and therefore the use that this site
has been earmarked for is waste disposal.”
In fact, as parts of the quarry are
decommissioned the rehabilitation plan
is applied to that section. For instance, a
neighbouring tile factory has already been
back-filling them with its waste, explains
Von Wielligh.
“There is a pre-requisite that the
waste must be ‘green’ without plastic or
anything toxic, or otherwise we would
have to line the pit to orient leakage. Once
the last two mining seasons are complete,
we will commence a full rehabilitation
process to accelerate this plan to fill up
the quarry. The company has been in talks
with other companies who need waste
facilities in this regard. This is probably
the closest potential landfill site for many
companies in this area, particularly for
building rubble. Distance is key in waste
disposal,” he says.
The testing lab is used for factories all over the country.
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QUARRY SA | JULY/AUGUST 2019_19