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:: 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.
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