First Mining Drc-Zambia July/Aug 2019 First Mining DRC-ZAMBIA July-August 2019 digital | Page 13

PRODUCT
Reliability leads to repeat
crane order for Condra
T
hirty years’ reliable duty in a
corrosive environment has won for
Condra a repeat order from Lonmin
Platinum for an overhead tankhouse
crane to replace an identical machine
delivered three decades ago.
The original crane was installed in 1990
at Lonmin’s Middelkraal Farm refinery
outside Marikana, North West Province,
where it lifts and positions copper plates
and slabs within the acid tanks used
during the electrolytic refining process.
During this final phase, anodic copper
slabs with a 99 % purity attained during
three prior processes are suspended
by the crane in large tanks filled with an
electrolyte solution of copper sulphate
and sulphuric acid.
Small, thin sheets of pure cathodic
copper are then positioned between
these anodes and an electric current
applied. Copper ions leave the anodic
slabs and move through the electrolyte
to place themselves on the cathodic
sheets, which after time become thick
copper plates of 99,99 % purity, ready
for removal by the tankhouse crane for
rinsing and despatch to factories that
produce copper products.
Lonmin’s double-girder electric overhead
travelling crane has a span of 19,9 m, a
capacity of 5 tons, a lifting height of 7,7
m and two lifting speeds of 2 and 8 m per
minute. Long-travel speed over the 42 m
of the tankhouse is 80 m per minute.
Condra has delivered to other refineries
tankhouse cranes with long-travel
speeds as high as 140 m per minute,
more than three times the speed of a
standard crane and about as fast as an
average person’s jogging speed.
“To cater for a possible customer need
for higher speeds in the future, we have
included in Lonmin’s new crane provision
for an easy upgrade to frequency drives,”
explained Condra’s Managing Director
Marc Kleiner.
“Condra is currently investing in
improved digital loadcells to further
improve reliability across our tankhouse
line in general, even though the reliability
of the Marikana crane was well proven
over a period of three decades,” he said.
Lonmin’s new tankhouse crane will
incorporate features from Condra’s
design library that move it beyond
the company’s current generation of
tankhouse cranes. These include four
LED girder downlights to illuminate the
work area, remote crane control with a
pendant back-up, an electrical control
panel fitted with acid filtration ventilation
to cater for the corrosive tankhouse
environment, and a special paint finish
for the same reason.
Quality control will include inspection
and certification at defined stages of
manufacture, and there will be magnetic
particle inspection of the welding
seams to ensure airtight girders and the
avoidance of corrosion on the internal
faces.
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