Iamgold Considering Adding Heap Leach at Essakane Mine

Part of the Essakane feasibility study evaluates improvements to the mill seen above at night.
Iamgold has announced positive results from a prefeasibility study (PFS) of installing a heap-leach operation to process lower-grade mineralization at its Essakane mine in northeast Burkina Faso. Essakane currently produces about 390,000 ounces per year (oz/y) of gold from open-pit mining and CIL processing. The PFS contemplates added production of 72,000 oz/y from heap leaching over a period of 6.5 years, and total life-of-mine average production from Essakane of 471,000 oz/y over a period of 8.5 years.

Throughput to the CIL mill would average 12 million mt/y, and heap leach throughput would average 10 million mt/y to 2026. Life-of-mine cash costs are estimated at $707/oz, and all-in sustaining costs are estimated at $946/oz. Initial capital expenditures to develop the heap-leach operation are estimated at $155 million.

Heap leaching would run in parallel to the existing CIL plant. Dedicated primary and secondary crushing circuits, tertiary crushing using a high-pressure grinding rolls (HPGR) unit, material handling and stacking conveyors, and a carbon-in-column (CIC) adsorption plant would be installed. Loaded carbon would be transported to the existing plant for stripping and refining, where minimal infrastructure upgrade would be required. Where possible, the specified equipment would be same as is used in the CIL plant to improve maintainability and reduce parts inventories.

Additional major infrastructure included in the PFS are the leach pad, solution distribution and collection systems, solution ponds, camp upgrade, and increased power generation capacity.

Based on the PFS results, Iamgold has initiated work on a feasibility study to further optimize project design, secure longlead equipment, and improve project economics, with completion of the study planned for the first quarter of 2019. The feasibility study also will evaluate additional development alternatives, such as a gravity circuit upgrade and an increase in grinding capacity. This strategy aims to increase the throughput and recovery of the CIL and gravity circuits to bring additional value to the processing plant.

Mineral reserves at Essakane currently stand at 102.6 million mt at a grade of 1.17 g/mt gold containing 3.8 million oz of gold for CIL processing, and 61.9 million mt at a grade of 0.43 g/mt containing 845,000 oz of gold for heapleach processing.

As featured in Womp 2018 Vol 07 - www.womp-int.com