BATEMAN partners revolutionary
diamond rock sorter development
BATEMAN is partnering the University of the Witwatersrand, Johannesburg,
South Africa, and its commercialisation company, Wits Commercial Enterprise
(Pty) Ltd, in the development of their revolutionary new technology
for the detection, imaging and sorting of diamonds in kimberlite.
BATEMAN recently handed over a cheque of R570 000 to Wits for the
pilot-scale development work and will also be providing support in
the form of developing the materials-handling system for the pilot
test and plant-scale demo units, as well as carrying out the detailed
engineering and design for the two units.
The technology, dubbed DIAMOND-PET, is a diamond-bearing rock sorter
based on gamma-ray irradiation and positron emission tomography. It
offers the potential for significant savings in both capital costs
for new mines and operating costs for new and existing mines, as it
would make possible the early selection for processing of only those
rocks that contain diamonds. Since the proportion of rock particles
containing diamonds is very low, with current technology a ton or
more of ore must be processed to extract only a few carats of diamonds.
Therefore this device has the potential to dramatically reduce the
amount of material to be processed in order to recover the same diamonds
through a dense-media separation plant, for example.
Preliminary tests on kimberlite estimate that, with DIAMOND-PET,
in excess of 99 % of the rock could be rejected as waste. As an example,
it is estimated that as much as 99,95 % of rock at an average rock
size of 5 cm could be rejected, which is equivalent to the need for
two days processing as opposed to the one year required with currently-available
technology for the same volume of rock extracted.
Gamma-ray irradiation offers many advantages over other potential
technologies, as it is, for example, more effective in penetrating
the rock than X-ray imaging, and more cost effective and safer than
neutron detection. Suitable technologies to build a DIAMOND-PET plant
are readily available commercially, such as linear accelerators and
detectors which are widely used in the medical profession.
The technology makes it possible to quickly locate concentrations
of carbon within the rock, and therefore to identify the presence
of diamonds. With DIAMOND-PET, the ore is irradiated with gamma rays
which results in the emission of a positron which combines with an
electron to release a pair of oppositely directed gamma photons. It
is the detection of these photons that indicates the presence of carbon.
The potential of DIAMOND-PET for diamond recovery was first identified
by Professor Friedel Sellschop at the University of Witwatersrand
and this was confirmed in laboratory tests by Wits between 2000 and
2004. The programme is now entering the pilot-testing phase, due to
be completed by the end of 2006, to determine critical operating parameters
such as detection periods and sensitivity. Software for tracking emission
locations and superimposing the emissions to identify carbon-concentration
locations will also be developed.
In practical application, it is envisaged that DIAMOND-PET could
be installed underground with the crushing system for selection of
rock near the source and disposal of barren material underground,
or immediately after a surface primary crusher for early diversion
of the waste material to the tailings.
For further information, please contact James Nieuwenhuys, General
Manager, Diamonds, on +27-11-899-2262 or
e-mail diamonds@batemanengineering.com.
Also see www.wits.ac.za/enterprise/
for more information on the activities of Wits Enterprise.
