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PRODUCT News
42
MODERN MINING
March 2016
Marthinusen & Coutts recently performed
an extensive rehabilitation of an old
2 985 kW salient pole synchronous mill
motor that had not been in use for over 10
years.
The project was commissioned by
international mining company Newmont
for the Waihi opencast gold mine in New
Zealand. Marthinusen & Coutts took on the
project after initially agreeing to retrieve
themotor fromwhere it had been left lying
in the veld at the site of the old Crocodile
River gold mine at Hartebeespoort Dam
near Skeerpoort, Gauteng.
“We were first awarded a contract
to assess the condition of the motor to
establish what sort of state it was in and
to then quote for repairing it,” says Craig
Megannon, GM at Marthinusen & Coutts.
“Not surprisingly we found it to be in
a poor state. Apart from the fact that it
had been left abandoned for so many
years, it is a very old motor. It was manu-
factured in Japan in 1970 and had since
been deployed at mining operations in
Australia, Argentina and South Africa.
“Repairing it has involved an extensive
amount of work and included complete
remanufacture of parts that we found to
be beyond repair,” Megannon says. The
rehabilitation contract was awarded in
October 2014 and was completed at the
Mill motor rehabilitated for New Zealand gold project
Marthinusen & Coutts’s test technician, Suresh Gunpat,
with the 40-pole synchronous mill motor during the series
of tests conducted on it on completion of the rehabilita-
tion process.
end of October 2015. The repairs that were
done included rewinding of the rotor and
replacement of the stator core with lamina-
tions manufactured by Electrical Machines’
Laminations & Tooling business unit. Parts
that were replaced with re-manufactured
parts included the journals, slip-rings,
brush gear and coupling.
“We also modified the stator design to
increase the stator copper thickness and
reduce the overall temperature rise, which
we found to be the main limiting factor
in the stator in its original form. We did
the design using advanced software we
recently acquired for this type of special-
ised work,” he explains.
Machine Monitor, an Australia-based
third par ty engineering company,
observed andmonitored the entire rehabil-
itation process and testing at Marthinusen
& Coutts’ Cleveland plant throughout the
duration of the contract on Newmont’s
behalf.
Marthinusen & Coutts, tel (+27 11) 607-1700
New generation excavators from Doosan introduced
Doosan’s newest generation hydraulic exca-
vators – the heavy duty DX225LCA series
– have been designed for greater operator
comfort, improved fuel efficiency, enhanced
productivity and minimal maintenance
requirements.
“There are currently 360 20-t Doosan DX
excavators in operation in the local market
and we expect the improved DX225LCA
series to further consolidate Doosan’s
position as a leading supplier in this size
class of equipment,” says Chris Whitehead,
National Sales Manager, DISA Equipment
(Pty) Limited, trading as Doosan, part of the
Capital Equipment Group (CEG) of Invicta
Holdings Limited. “These robust excavators,
which are now available in Southern Africa,
are fitted with special features to ensure
optimum efficiency and extended service
life in harsh local operating conditions.
“Design features for the African mar-
ket include a Tier II mechanical engine for
reduced operating costs, a heavy duty
boom and arm, as well as standard hydrau-
lic piping for hammer applications. These
machines also have an improved H Class
bucket and are supported by Doosan with
a 2-year/ 4 000-hour warranty.
“This series features a range of new tech-
nologies that deliver effective control over
the machine’s power and also simplify main-
tenance procedures. As a result, efficiency
and machine durability are increased, pro-
ductivity is improved and operational costs
are lowered.”
The 21,5-t operating weight of these
excavators is enhanced by new specifica-
tions that include a 0,92 m³ bucket capacity,
a digging depth of 5 755 mm, a digging
reach of 8 950 mm and a digging height
of 9 750 mm. The engine rated power is
110 kW at 1 900 rpm. Maximum engine
torque is 61,5 kg.m/1 400 rpm.
Doosan, tel (+27 11) 974-2095