Extensive metallurgical testwork has defined that the most effective gold recovery process for Chaarat is whole ore pressure oxidation followed by cyanidation to produce gold and silver doré. Overall gold recovery using this process has been estimated at 92%. Based on these design criteria a conventional crushing, screening and grinding circuit has been designed using three stages of crushing followed by a ball mill. The milled material after treatment for pH adjustment and pre heating is fed into an autoclave where it is heated under pressure in the presence of oxygen to oxidise the sulphidic minerals. The oxidised material is fed into a CIL battery of tanks where it is stripped of gold. Tailings from the CIL circuit will be detoxified prior to disposal in a conventional tailings dam.
The plant will be operated continuously with a planned throughput of 1,850,000t per year. Annual gold production will average approximately 202,000oz with a total of 2.48Moz of gold to be recovered over the life of the mine. Doré produced on site will be sold for further refining.
In order to reduce the technological risk, initially or in general, it is possible to add a flotation circuit and process the flotation concentrate by the same POX method. The gold recovery from the concentrate will improve to 95% but as the gold collection to the concentrate will only be 86%-90%, the overall gold recovery was conservatively estimated to be 82% for this scenario. This alternative was not evaluated at the same level of detail as the whole ore treatment.