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PRODUCT News
48
MODERN MINING
September 2016
Billions of litres of diesel are consumed
annually by the global mining industry,
which is under severe pressure from weak
commodity prices. Up to 80 % of this costly
fuel consumption comes from haulage
trucks moving uphill on ramps.
A Namibian uranium mine is overcom-
ing this challenge with six 11 MW Siemens
substations that provide electric power to
the overhead DC (Direct Current) power
lines, which in turn provide the DC power
to the adapted diesel-electric haulage
trucks.
Siemens SA launched one of three com-
pleted units at its North Riding facilities
recently. They will be used to power a fleet
of Komatsu 960E trucks, which are among
the industry’s biggest and highest capacity
mine haulage vehicles, with a load capac-
ity of 214 m
3
or 327 tonnes.
Another breakthrough for this new
order is that 90 % of components in the
containerised substations are entirely
manufactured by Siemens, compared to
past units that contained approximately
30 % Siemens components.
“Consistent innovation has kept us at
the forefront of mining technology, and
sourcing nearly all of our components
internally means greater quality con-
trol, improved functionality, and greater
capacity,”says Siemens SA Project Manager
Phiwa Thindwa.
Each 11 MW containerised substa-
Six Siemens substations for trolley assist system
tion boasts 1,8 kV of DC voltage and up
to 10 000 A to ensure that it can run two
trucks continuously, three trucks for ten
minutes or four trucks for one minute
along the overhead power lines. This com-
bination of substation and overhead line is
known as trolley assist technology.
A trolley assist solution is installed on
any uphill stretch between the mineral
ore loading (pit) and offloading (dump or
process plant) points, as the speed on the
gradient is limited by the diesel engine’s
horsepower, Thindwa explains.
With the inclusion of the electric drives,
the electric power supplied to the wheel
motors of the haulage trucks enables the
vehicles tomove faster uphill, which results
in quicker turnaround times and higher
productivity for the mining operation.
Engine operating and maintenance
costs are directly linked to hours of opera-
tion of the haulage trucks and using trolley
assist on gradients reduces the cycle time
of the haulage trucks, thus increasing the
intervals for maintenance.
Siemens’ DC containerised substa-
tions are manufactured in Pretoria with
components currently imported from
Germany. “The company aims to manu-
facture components such as switchgears
and control panels locally in future,” says
Siemens SA Country Business Unit Lead:
Rail Electrification, Joey Govindasamy.
Siemens’ trolley assist solutions for
the mining sector were first developed in
South Africa in 1981, and the local opera-
tion has since remained a global leader in
installed capacity. Currently Siemens SA is
the only provider of the trolley solution in
the Siemens group.
Siemens, tel (+27 11) 652-2000
New generation conveyor belt for coal mines
ContiTech South Africa has designed, man-
ufactured and installed a new generation
solid woven conveyor belt, Coal Flo, for use
in underground coal mining applications.
“This four-layer PVC belt illustrates
our ability to produce a new generation
conveyor belt at a reduced cost through
innovation and extensive research and
development,” says Avril Botha, Managing
Director Conveyor Belt Group at ContiTech
Africa. “This is essential in current mining
market conditions where it is paramount for
suppliers to have the capability to reduce
cost to clients without compromising qual-
ity of product.”
Four rolls of 250 m of Coal Flo have
been installed on South 911 Irenedale
Bosjesspruit in Secunda, Mpumalanga. The
belt is being used by Sasol in a trunk con-
veyor belt application. Bosjesspruit is one of
five underground coal mines belonging to
Sasol and has 47 km of underground con-
veyor belting installed.
Due the presence of methane gas in
underground coal mines, equipment used
needs to be flame retardant. With this is
mind, Coal Flo has been manufactured to
comply with specifications contained in the
SANS 968:2013 regulations.
“We expect the installed product to have
a lifespan of four years during which it is
expected to convey up to 25 million tons
of coal,” explains Botha. “During the test
period, Sasol will analyse the performance
of the belt and make a decision regarding
the replacement of existing conveyor belts
in its underground coal mining operations
with ContiTech’s Coal Flo. Preliminary feed-
back on the performance of the Coal Flo
belt is favourable, but a long-term evalua-
tion is required for in-depth analysis.”
Paul van Zyl, ContiTech South Africa, tel (+27 11) 248 -9337