Modern Mining January 2018

GOLD

maintenance costs, as both Houndé and Endeavour’s Karma mine (also in Burkina Faso) have similar fleets. The plant comprises a single- stage primary crushing circuit and a two-stage SAG (with pebble crusher recycle)/ball milling in closed circuit with hydrocyclones to produce a P80 grind size of 75 micrometres. A gravity concentra- tor and Intensive Leach Reactor (ILR) have been included in the design as per the FS. The CIL cir- cuit comprises eight CIL tanks containing carbon for gold and silver adsorption with oxygen sparged from two 25-tonne PSA oxygen plants and an 18-tonne split Anglo (AARL) elution circuit. Electrowinning and induction fur- nace smelting complete the gold doré production process. A cyanide detoxification and

arsenic removal circuit is included in the pro- cess facility design, for treatment of process residue before discharge to the fully-lined 57 Mt Tailings Storage Facility (TSF), located adjacent to the processing facility. Feed water for the processing facility will come from vari- ous sources such as pit dewatering bores, the Cavally River (for make-up) and decant return from the TSF. The processing plant is similar in design to Houndé, with identical ball and mill designs. Among key changes from the FS design are the addition of a high-speed 20 MW diesel backup power station, an upgrade in the crusher (it will be a C160 from Metso), an increase in the diameter of the pre-leach thickener to 38 m, an increase in the number of CIL tanks from six to eight, and an increase in detox and arse- nic destruction capacity to control significant Cu and As in the ore. Reagent mixing/storage capacity has also been increased. Apart from the higher production due to the fourfold increase in throughput, advantages of the CIL plant compared to the current heap leach facility include lower processing costs, higher recovery rates on oxide ore, and the abil- ity to process a range of ore types. Endeavour is currently anticipating that the heap leach oper- ation will be discontinued once the CIL plant is commissioned. In terms of progress, Lycopodium (the lead engineer on the FS and the OS) has been appointed as the EPCM contractor, a role which it also fulfilled at Houndé. Long-lead items have been ordered and US$116 in spend had

already been committed as at mid-November. Current work on site is concentrating on bush clearing and process plant earthworks and is reportedly progressing well. Along with Houndé, the Ity CIL project is key to Endeavour’s plan to grow its annual produc- tion to plus 800 koz/a of gold at a group AISC of under US$800/oz by 2019 (with mine lives at all its operations of over 10 years). Beyond Ity CIL, Endeavour’s next ‘build’ will almost certainly be Kalana in Mali, which it acquired in 2016 from Avnel. A feasibility study on the project was completed by Avnel and is cur- rently being optimised by Endeavour. Once developed, it will be a somewhat smaller mine than either Houndé or Ity CIL but neverthe- less an attractive one, with an average annual production that is likely to be in the region of 150 000 oz/a. Looking further out, Endeavour has one of the biggest exploration programmes in West Africa (it spends about US$40 million a year on this function) designed to not only increase reserves at its current mines but also identify new ‘greenfield’ projects. Given this commit- ment and the company’s already outstanding track record in exploration, there is a good chance that the Ity CIL project and Kalana will be followed by further new mines and certainly one would not be surprised to see the group’s annual production nudging – or even exceed- ing – the million-ounce-a-year mark within the next several years. Report by Arthur Tassell, photos courtesy of Endeavour Mining

View of the existing heap leach operation at Ity.

The processing plant is similar in design to Houndé, with identical ball and mill designs.

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January 2018  MODERN MINING  41