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MODERN MINING
January 2016
DIAMONDS
Top projects
P
etra announced the approval for
the project in April 2015. The con-
tractor charged with delivering
the plant is MDM Engineering and
work on site has been on-going over
the past several months, although the peak of
construction is only due later this year (2016).
The plant will be commissioned and enter
operation in Petra’s H2 FY 2017 (i.e. by June
2017). Orders for all the long lead items – such
as the AG mill and the High Pressure Grinding
Rolls (HPGRs), which will both be supplied by
Polysius – were in place by September 2015.
The current plant, although it has under-
gone various refurbishments since being
commissioned nearly 70 years ago, has become
increasingly expensive to maintain due to
its age and operational complexity and has
required the commitment of significant stay-in-
business capex in recent years. Moreover, it is
also based on old crushing technology, which
Petra believes does not offer the best potential
for optimal diamond recoveries.
A feature of the new plant will be a much
reduced footprint compared to the existing
facility – it will cover just 5 ha compared to
26 ha. This will result in a commensurate
reduction of the ‘infrastructure’ required. For
example, only 22 conveyor belts totalling 3 km
in length compared to the 151 conveyor belts
used at present, which extend over a total dis-
tance of 15 km, will be required. There will be
only 22 screens compared to four times that
number in the existing plant while the number
of pumps will reduce from 121 to just seven
and electric motors from 589 to 84. Moreover,
only two substations will be needed as opposed
to 17 currently.
The plant – which will feature a high level of
automation and a total ‘hands-off’ final recov-
ery section – will have a throughput capacity
of 6 Mt/a with the initial feed comprising
4 Mt/a of ROM and 2,3 to 2,5 Mt/a of tailings.
New Cullinan plant
will
The base for the XRL (X-ray
luminescence) plant at
Cullinan.
One of South Africa’s oldest andmost famous diamond
mines is to get an entirely new, state-of-the-art processing
plant which will replace the current sprawling treatment
complex which dates back to 1947. Petra Diamonds, the
owner of Cullinan, estimates that the energy-efficient facility
– which will incorporate autogenous (AG) milling and X-ray
fluorescence (XRF) technology – will improve revenue per
tonne by 6-8 %and will pay for itself within about three years.
The cost of the project is estimated at R1,65 billion.