Ann: Development Progress - Lindi Jumbo Mine, page-110

Hi Stirer, you are on the right path now, recognising the importance of output as distinct from purely focusing on nameplate throughput capacity. Throughput is measured in tonnes but output is dependent on tonnes and grade. On the grade, Walkabout have adopted the DFS assumed dilution of only 5 percent. Please refer to the attached paper from Anglogold Ashanti's Iduapriem open pit gold mine in Ghana. Despite the orebody being homogeneous dilution is calculated to average 20 percent. In an underground mine you can use a variety of stoping methods. Cut and fill might achieve 5 percent dilution but block caving is likely to involve dilution in excess of 20 percent. Open pit dilution is likely to be closer to 20 percent than 5 percent and that assumes you are mining all of the ore. If you are intending to mine and process the high grade portions only, which in the case of Lindi is less than 15 percent of the overall orebody, dilution with combined waste and low grade is likely much higher than 20 percent. The assumption of just 5 percent dilution is a major technical risk.

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