2005 - Putzmeister

Special concrete
The ZX delivery line in the lattice tower of the
crane runs to the sliding formwork
New platinum mine
in South Africa:
concrete placement on
109 m high pit frame
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Platinum and its costly mining
Platinum is currently almost twice as expensive
as gold, and significantly harder.
World-wide, only approximately 200 tons
of this precious metal are mined each year,
with 90 % of the production stemming
from South African mines. Platinum is
required, for example, for the production
of catalytic converters in the automotive
industry, in dental medicine, in space travel
and for the production of jewellery. To
acquire 15 grams of pure platinum, up to
five tons of stone must be exploded, conveyed,
pulverised and chemically treated.
The metal is prepared above ground in
high security areas. The platinum discovery
sites around the Rustenburg region
were mined in a strip of approximately
400 km. Here, 27,000 miners work under
the hardest of conditions at depths of
approximately 2,000 m. With an air humidity
of 90 %, there are temperatures at this
depth of up to 50 °C. The platinum reserves
were discovered in 1924 by the German
geologist Hans Merensky. The land rights
in Rustenburg belong to the Bafokeng
clan, to which the IMPALA PLATINUM
group assigns 5 % of its profit each year
as payment for rights of use.
In Rustenburg in South Africa, the
IMPALA PLATINUM LTD mining company
is investing significant sums of
money in the mining of the precious metal
platinum. In the meantime, work is being
carried out on the completion of the 16th
shaft. Already before commissioning,
Putzmeister pumps were used here,
although not for pumping residues from
the ore dressing (tailings), but for highrise
concrete pumping.
In addition to constructing the shaft and
connecting a new mining field to the existing
mining fields, the tapping of a new
mine also includes the installation of a pit
frame. At its tip, the pit rope, to which the
haulage skips for bringing up the mined
material and the baskets for transporting
the miners are attached, runs over a large
pulley. In order to move the largest loads
possible, or to achieve short circulation
times, the pit frame must be of a certain
height. At the 16th pit of IMPALA in
Rustenburg, the tower is certainly not too
small: with a base of 21 m x 20 m and a
pulley at the record height of 109 m, the
new pit is designed for extraordinary conveying
capacities.
A sliding formwork adapts to different
wall thicknesses
The work on the pit frame with several
integrated concrete decks began with the
pit brow at a depth of approximately 25 m.
The main contractor assigned with the
construction work is RENNIKS CON-
STRUCTION. The project, costing around
80 million rand (approximately EUR 10
million), also includes the construction of
the main ventilation shaft, several access
tunnels, the foundation of the conveying
system and various digging works.
Completion is planned for May 2006.
The walls of the pit frame, which are
between 0.95 m and 0.55 m thick, were
constructed using the sliding formwork
procedure. Here, the formwork adapted
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PM 3723 GB
Truck mixers load the BSA 1408 E with a special type of concrete
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In total, approximately 21,000 m 3 of concrete are processed
at the pit frame
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The PM gate valves are activated via a hydraulic circuit
in the stationary pump
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flexibly to the wall diameter which becomes
thinner as you move upwards. The contract
for concrete delivery was awarded to the
specialists from MURRAY & ROBERTS
CONSTRUCTION, who, incidentally, have
been working with Putzmeister pumps for
many years.
In total, 7,000 m 3 of concrete was required
to construct the carcass of the pit frame.
The concrete used had a specially developed
mixture breakdown. It contained,
amongst other things, aggregate with a
maximum particle size of 19 mm (of which
50 % was slag), drift sand, stone dust and
various concrete additives. The further
details of the concrete composition are
considered to be confidential. In other construction
measures within the project, a
further 14,000 m 3 of concrete was placed.
The "chief operator" has full control of his Putzmeister
stationary pump. On the left you can see the cable
remote control of the BSA 1408 E
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BSA and rotary distributors
work as a team
The free-pumping material was delivered
by MURRAY & ROBERTS with a
Putzmeister BSA 1408 E via a ZX high
pressure line, which was mounted on a
tower crane. With a hydraulically activated
gate valve, the concrete flow in the pipeline
could be interrupted, for example for cleaning
operations on the stationary pump.
A second BSA was kept ready as a standby
pump. The crane was set up about three
metres from the carcass and mounted with
cross-beams in the continuously rising
structure. The upper end of the riser was
connected with a flexible hose (DN 125),
so that a connection to the RV 10 rotary
distributor on the sliding formwork could
be established at any time in the 90 ° delivery
line bend. Incidentally, this too was a
device manufactured by the Putzmeister
subsidiary in South Africa. In the interest
of the most unrestricted slewing circle
possible, the construction company elevated
the four support legs of the deck distributor
by approximately 5 m.
Service technicians available at all times
During the carcass construction phase,
employees of Putzmeister South Africa
were on site at least once a week. They
trained the concrete pump operators, gave
tips on cleaning and maintenance of the
BSA and clarified any service questions.
In addition, the PMSA emergency service
was also available 24/7 via a hotline.
A service technician could have been on
site within 2 hours, if required.
As the construction progressed, additional
pipe sections were used between the riser
and the delivery hose. On average, the pit
frame grew by 4.5 m each day, with the
best daily performance being 6 m. At
109 m, the BSA 1408-E reached its highest
pump height on the new IMPALA pit.
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PM 3723 GB