Re-treating diamond-bearing
dumps
As part of the new partnership model introduced at the start of
the year (see BATEMAN Globe No. 39, January 2004), De Beers has involved
BATEMAN in a number of projects to recover diamonds from tailings
dumps at its older mines.
These dumps contain reject material deposited over many years when
the diamond-recovery processes were not as efficient as they are today
and are now known to contain meaningful amounts of small diamonds.
The possibility, however, of finding larger stones too is not excluded.
James Nieuwenhuys, BATEMAN General Manager, Diamonds, reveals that
studies are being conducted on about a dozen different diamond-recovery
routes which could be applied to the reprocessing of dumps, the objective
being to have available a suite of processes applicable to all kinds
of dump materials and to contain dump-reprocessing costs to an absolute
minimum.
In respect of milling, the partnership will be exploring a combination
of Western and Russian technologies, arising out of testwork undertaken
by BATEMAN a few years ago in Siberia for a large diamond exploration,
mining and marketing company in the Russian Federation.
The key to the milling technology is the slow mill speed which minimises
diamond breakage. As many dumps are in arid locations, water usage
will also have to be minimised. BATEMAN has entered into agreements
with suppliers of novel milling technology, such as cantilever and
planetary systems and innovative liners, so these can be evaluated
for use in dump reprocessing.
Some of the novel technology is already finding application in current
projects BATEMAN is undertaking with De Beers. At Namdeb's E-Bay diamond-liberation
project in Namibia, the wet-crushing system being installed is the
first of its kind in the De Beers Group (see BATEMAN Globe No. 38,
November 2003) and enables the plant to treat all potentially viable
deposits including clay-rich and very hard cemented materials.
Because of the remote location of many of the dumps and the potential
need to relocate the equipment from time to time to other nearby dumps,
BATEMAN is drawing heavily upon its experience with modular-processing
plants which will be applied to all the major processes needed for
diamond recovery, e.g. crushing, milling, dense-media separation,
X-ray recovery, etc.
According to Nieuwenhuys, several factors motivate projects to re-treat
old dumps. "There is today a greatly improved understanding of
diamond-liberation processes and more effective methods to recover
the diamonds are available," says Nieuwenhuys. "At the same
time, the kimberlite in the old dumps has weathered extensively during
years of exposure to the elements, facilitating the release of any
diamonds associated with the kimberlite. Also, the availability of
high-quality primary resources is decreasing and diamond producers
are on the lookout for additional resources."
"All old diamond mines have such dumps and this includes all
the mines in South Africa, Botswana and Namibia," says Nieuwenhuys.
"In South Africa, the newly promulgated Mining Charter, which
fosters a 'use-it-or-lose-it' approach to the exploitation of mining
resources, is making mining companies take a far more careful look
at smaller deposits. Accordingly, BATEMAN is in discussion with several
black economic-empowerment companies aimed at providing the technology
and backup required to get these ventures started.
"Further afield, the improving political situation in the Democratic
Republic of the Congo (DRC) and Angola is also opening up possibilities
there. Sampling programmes in Canada, for which BATEMAN equipment
has been purchased in recent years, are also revealing promising recovery
ventures."
For more information, please contact James Nieuwenhuys, on +27-11-899-2262
or email diamonds@batemanengineering.com.
VIEW
PDF
©
Copyright BATEMAN 2004
