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:: Super Stone's Diamond-recovery Plant Features Grease-belt and X-ray Circuits
A diamond-recovery module, comprising grease-belt and primary X-ray circuits, has been supplied by Bateman to Super Stone Mining (Pty) Ltd (a wholly-owned division of black-owned Ekapa Mining (Pty) Ltd) at a site near the old De Beers Mine pit in Kimberley, Northern Cape, RSA. A containerised module with grease- and X-ray-recovery circuits is believed to be a first in the diamond-mining industry.
Ekapa / Super Stone is contracted by De Beers to reprocess some of the kimberlite dumps which have been deposited in the area over the past 80 years. The availability of improved metallurgical processes has made the dumps more amenable to retreatment.
Together with the dense-media-separation (DMS) module, also supplied by Bateman, the recovery plant is capable of recovering up to 98 % of the diamonds in the old dumps. A reconcentration section was incorporated in the plant to minimise the amount of concentrate to be sorted in the primary glove-box circuit. As the plant permits an efficient, totally hands-off concentrating operation, security is also enhanced.
According to Ekapa MD, Jahn Hohne, a very important factor in the decision to install the module was its cost. The incorporation of a grease-belt circuit to reduce the amount of concentrate from the DMS module that has to be processed by the X-ray reconcentrator circuit reduced the latter's required capacity and hence the capital cost of the overall plant.
The recovery module processes 4,5 t/h of DMS concentrate. Of this, 4 t/h of the fine material is fed to the grease belt and the remainder to the primary X-ray circuit. The concentrate from both circuits is then fed to the X-ray reconcentration section and subsequently to the glove boxes for final diamond recovery. A vault has been provided to store the diamonds before export. Tailings from the respective circuits are either reprocessed or sent to the tailings dumps.
Super Stone's recovery plant was ordered in October 2003, delivered to site and commissioned at the end of May 2004. It is accommodated in three standard 12 m-long containers which were modified to accommodate the equipment. An efficient dust-extraction system is installed in the containers housing the X-ray circuit, where dry material is processed, and all of the containers are air conditioned and thermally insulated to provide pleasant working environments. The use of containers ensures that the recovery plant can easily be dismantled in the future and moved to a new location.
The DMS module, handling 20 t/h of dump material, is a standard Bateman unit and was delivered to site in February 2004.
This was a particularly successful project in which Super Stone's participation and contribution of ideas, particularly during the design phase, augmented Bateman's capabilities in the development of an innovative solution for the recovery of diamonds from old kimberlite dumps.
Bateman Project Engineer
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