Mine excursion uses scalping screens . However , where a large percentage of the material is ‘ washable ’, the mined material is sent to the plant directly . The processing plants consist of a configuration of scrubbers , screens , spirals , and magnetic separators to liberate and extract the chromite from the -1mm fraction .
According to Marike Barnard , process manager at ACF , the new thickeners are being installed to improve water recovery and efficiency . “ With the new thickeners , we are recovering about 80 % of our water , which reduces the environmental impact , and we don ’ t source as much water from the boreholes as we used to . The slurry that is pumped out now dries out faster and we are able to return it to the rehabilitation areas a lot quicker . Not only does it reduce our environmental footprint , but it also ensures better water quality and better production and efficiencies in the plant , and eventually , a betterquality product ,” says Barnard . ACF has purchased thickeners for all the plants , but they are still to be installed at all the plants . A second thickener will be commissioned at Plant 6 soon , and after that Plant 5 , Plant 1 , and Plant 4 will be boosted by new thickeners . All of these thickeners are manufactured and installed by South Africa-based Magra .
According to Kaka , the clarified process water recovery from the six plants amounts to 1 774m ³/ h , resulting in massive savings and a recovery of 82 % of the process water directly from the thickener . “ Processing of thickened tailings will amount to an additional 112m ³/ h of process water recovered from the dewatering screens , with the benefit of having a conveyable virtual dry tailings product at 20 % moisture content . This product can be loaded and transported together with the discard rock to the mining area for rehabilitation and full utilisation of what was practically an empty truck ,” says Kaka . The total estimated water recovery is about 87 %, including water recovery from the screens . Only a fractional 13 %, amounting to 284m ³/ h of borehole make-up water , is required for all six plants . Module water specifics vary from plant to plant and depends significantly on the split .
ACF operates a unique project in a unique country . Zimbabwe is on the recovery path after Mugabe ’ s devastating rule . Foreign investment is on the rise , and many new projects are in the pipeline . However , the reward for companies that entered Zimbabwe when others fled will be so much better . ACF is now established in the country and according to Kaka , the mine has acquired enough claims to keep it going for at least another 12 years . They rode out the tough times and is now on a growth path next to none . They have a good relationship with the new government and plans are afoot for several new projects in Zimbabwe , including in the gold mining as well as platinum and lithium space . b
JULY 2018 MINING MIRROR [ 19 ]