Upgrade of Namdeb's 3-Plant diamond-treatment facility
Namdeb has awarded Bateman Engineering a R115 million contract
to upgrade an existing diamond treatment facility in Oranjemund on
the west coast of Namibia to re-treat tailings dump material. The
dump contains about 24 million t of tailings accumulated during the
past 30 years of diamond mining in the area.
The diamond-recovery processes used previously were not as efficient
as they are today and these dumps are known to contain meaningful
amounts of small diamonds and possibly also some larger stones.
Phase 1 of the project will comprise both modifications and additions
to the plant. A new dump-reclaim section, utilising tipping hoppers
and a conveyor, will feed the new front-end screening facility comprising
receiving bins, brute-force feeders, vibrating scalping screens and
associated conveyors to remove product and waste.
In the existing scrubbing facility three scrubbers will be removed
and replaced with bypass chutes. Later, the remaining scrubbers will
be removed and bypassed, leaving only the screening operation in place.
The existing secondary-crushing circuit will also be upgraded by
replacing the three old-generation crushers and a small jaw crusher
with four new-generation Sandvik cone crushers with fully automated
on-line gap settings. Though smaller than the out-going crushers,
they will liberate the diamonds more effectively. The crusher's discharge
screens may also be replaced, depending on their performance during
the commissioning and ramp up phase.
The feed to the existing dense-media separation (DMS) plant, which
is currently split into two streams, will be converted to three-streams,
with the third feeding a new 200 t/h Bateman Modular DMS Plant.
In the existing DMS building, the old mixing boxes will be replaced
by more efficient standard units. The old cyclone feed system, comprising
two Multotech 610 cyclones per stream, will be replaced with new distributors
and feed hoses and four Multotech 420 cyclones per stream, to accommodate
the change in the feed-size profile. It is also possible that a new
silo system will be installed to control the collection of concentrate
from all of the DMS plants.
When the current run-of-mine campaign at the mine is completed, the
existing tailings conveyor will be stopped, swung through 180 ¼
and refurbished as necessary, and become the new tailings-dump start-up
conveyor. A new environmentally friendly, low-profile tailings dump
will be established on the existing mined out areas.
Phase 2 is scheduled to commence in 2007 and be completed in the
third quarter of the year. A preferential jaw crushing plant will
be installed to take crusher oversize material and further liberate
any diamonds. This will convert the plant from a closed to an open
circuit and effectively provide tertiary crushing at the plant. A
study is still being conducted on the addition of a thickener to close-loop
the water-reticulation system.
This is one of several projects to recover diamonds from tailings
dumps at older mines in which De Beers has involved Bateman Engineering
as part of the new partnership model between the companies introduced
towards the end of 2003.
For more information, please contact: James Nieuwenhuys, Bateman
Engineering Senior General Manager, Diamonds, or Darrell Jooste, Bateman
Engineering Project Manager, on +27-11-899-9111 or email diamonds@BatemenEngineering.com.
