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November 2015
MODERN MINING
35
PLATINUM
D
esign of the No 2 Shaft headframe
for the first phase of Ivanplats’
Mokopane project commenced
in 2014. The project, designed
to produce 433 000 PGM ounces
per annum, will ultimately be a 12 Mt/a opera-
tion. Ivanplats is a wholly-owned subsidiary
of Ivanhoe Mines.
The design of the No 2 Shaft headframe
was awarded in June 2014 to shaft-sinking
expert Murray & Roberts Cementation. It will
be the main production shaft, capable of hoist-
ing 6 Mt/a of ore, and will also transport large
mechanised equipment between surface and
underground.
By comparison with most steel-frame PGM
headgears in South Africa, it will be a consider-
able concrete structure – 100,5 m in height. The
lined shaft will be 10 m in diameter. The head-
frame will house all equipment necessary for
sinking and operating the shaft thereby reduc-
ing the surface footprint.
The No 2 shaft will be sunk to a depth of
1 080 m and will accommodate two “high mass,
high speed” 40-t skips running at 18 m/s, Genis
says. It will also be capable of conveying 225
persons in a single deck using a cage and coun-
ter weight arrangement.
“This milestone achievement can largely
be attributed to our Platreef project team, who
dedicated themselves to delivering a functional
quality design,” says Genis.
Ivanplats expects to start early works for
the No 2 shaft this year, including the boxcut
and hitch foundation civil works. The boxcut
designs are complete and the contract for the
early engineering works for the winding equip-
ment has been awarded to South Africa-based
FLSmidth.
The tall headframe will be located in close
proximity to a number of communities, Genis
notes. “As a result, we have incorporated unob-
trusive lighting and have also implemented
Design of
high-tonnage
headframe
completed
design initiatives to reduce noise and dust lev-
els. The overall aesthetic look also had to be
considered and subsequently we have designed
a simple headframe with fluted features using
concrete throughout.”
The “limited real estate” necessitated that
the two tower-mounted Koepe winding sys-
tems be positioned about 82 m above ground.
Additionally, a single drum auxiliary winder is
mounted at a lower elevation in the headframe.
“Working at these heights with heavy con-
crete and steel loads presents significant
constructability challenges,” principal engi-
neer Charles Bethel admits. To compensate
for potential obstacles in this regard, Murray
& Roberts Cementation established close ties
with its infrastructure sister company and
spent a significant portion of its time review-
ing handling equipment and crane lifting
arrangements.
Time was allocated to power supply, cabling
and piping layouts to ensure circuits which
will be easy to install and maintain. Chiller
plants located on the headframe roof will form
a HVAC (heating, ventilating and air condition-
ing) system to cool the winding equipment and
pressurise the upper three levels.
“Our headframe design provides Ivanplats
with pre-sinking flexibility from either the col-
lar or lower level, enabling a fast transition
into actual shaft sinking,” says Jan Vermaak,
Murray & Roberts Cementation mine engineer-
ing manager.
A purpose-designed sinking headgear is not
required for the initial sinking phases. “We
have incorporated start-up sinking arrange-
ments into the main headframe. By mass,
approximately 93 % of the steel required for
the headframe will be permanent at the start
of sinking, meaning the changeover from sink-
ing to permanent will be minimised,” says
Bethel. This equates to cost and time savings
for the project.
Murray & Roberts Cementa-
tion has recently completed
the design of Ivanplats’
mechanised, high tonnage
Platreef No 2 shaft head-
frame.
Murray & Roberts Cementation has demonstrated its high quality
design and drawing capabilities having recently completed the design
of Ivanplats’ mechanised, high tonnage Platreef No 2 shaft headframe.
The design of a headframe of this magnitude is a first for the company
and marks a huge milestone achievement, says Theo Genis, Murray &
Roberts Cementation study manager.
“Working at
these heights
with heavy
concrete and steel
loads presents
significant
constructability
challenges.”