COVER STORY
May 2014
MODERN MINING
23
featuring a rugged and durable frame struc-
ture that is intended for a long life with low
operating costs. “Simplified service and main-
tenance features reduce downtime, allowing
the machine to spend less time being serviced
and more time on the haul roads,” explains
Barloworld Equipment Kimberley Cat sales
professional, Hendrik de Wet.
Power is generated via a Cat 3508B EUI
(Electronic Unit Injection) engine delivering
a gross output of 746 kW (SAE J1995), whilst
the peak torque is 4 713 Nm. The 23 per cent
torque rise provides unequalled lugging force
during acceleration, on steep grades and in
rough underfoot conditions. (This torque rise
effectively matches transmission shift points
for maximum efficiency and fast cycle times.)
Both in terms of mining and downstream
mineral processing, liberation of the exposed
gravel is another key consideration when it
comes to equipment selection and application
technique. Here Steyn Diamante’s Cat track-
type tractors are used to rip up the diamond
bearing conglomerates. “The more you rip,
the better the grades, so you need to work the
gravel extensively to yield the best recover-
ies,” Steyn explains.
Liberated material is then loaded onto
track-mounted in-pit scalping screens, where
further process efficiencies are achieved: dia-
mond bearing materials under 80 mm that are
destined for the process plant are fed by con-
veyor into awaiting articulated trucks, reducing
double handling. Oversized material in turn is
loaded continuously for immediate dispatch to
designated rehabilitation zones.
In terms of beneficiation, Steyn Diamante has
eight pans at the processing plant, a DMS, and
the latest technology in high speed diamond
recovery. Initially, approximately 115 000 to
130 000 tonnes of diamond fissures gravel are
expected to be processed per month.
The final recovery plant will only treat
material sized under 45 mm. This equates to
a potential stone size of up to 400 carats, and
Bo-Karoo has yielded gems this large in the
past from across the full colour spectrum.
Examples include a 29-carat pink stone that
sold for around R55 million, plus a number of
D-Colour stones of more than 100 carats and
even a 300 carat light brown gemstone.
Initial exploration of Bo-Karoo’s upper ter-
race indicates that whilst the grade remains
low, the stones will be of higher quality. The
mining method will also differ, with drilling
and blasting required to open up the deposit.
Meanwhile, as mining progresses at
Bo-Karoo, production is ongoing at Steyn
Diamante’s other two operations, namely De
Kalk and Remhoogte.
Remhoogte, situated near Prieska, is simi-
lar in scope to Bo-Karoo. Lying approximately
105 m above the level of the Orange River, the
mine has an anticipated working life of eight
to 10 years.
A much older mine, De Kalk, situated in
the Upper Orange River, has the distinction of
being the site of South Africa’s first recorded
diamond discovery, and there are still good
gem yields being achieved.
On these two mines, articulated dump
trucks are being used. However, as the hauling
distances increase, along with the amount of
overburden, Steyn says that the logical move is
to switch to rigid mining trucks.
At the moment there are around 72 items
of earthmoving equipment within Steyn
Diamante’s mixed fleet to support the compa-
ny’s ongoing expansion plans.
“We have been experiencing strong growth
as a company in recent years and our past focus
on acquiring prospecting rights has now shifted
to the acquisition of mining rights that provide
larger and longer operational scope,” says
Steyn. “Going forward, for example, we are
investigating the potential acquisition of more
reserves in the middle Orange River.
“This is not an easy area to mine, but it’s
widely accepted that the best quality stones in
South Africa come from there. You just need
the right equipment, knowledge and skill to
extract the value.”
One of Steyn Diamante’s
Cat track-type tractors
being used to liberate the
exposed diamond bearing
conglomerates.
