The Fekola deposit is an example of a disseminated orogenic gold deposit.

The Fekola Mine is hosted within an inlier of Birimian rocks of the West African craton, termed the Kédougou–Kéniéba Inlier (KKI), located on the border of eastern Senegal, western Mali and northern Guinea. The KKI is a greenstone belt characterized by sequences of approximately north–south-trending volcanic and sedimentary rocks, intruded at various stages by gabbroic suites and calc-alkaline granitoids. The major greenstone units include the Mako, Dialé–Daléma, Falémé and Kofi Series rocks. Two main crustal-scale structures; the Main Transcurrent Zone (MTZ) in the west and the Senegal-Malia shear zone system (SMSZ) in the east, bisect the KKI. The Kofi Series hosts significant gold mineralization on the eastern side of the Senegal–Mali Shear Zone and is the primary host to mineralization in the Project area.

The Fekola deposit, including the Fekola North Extension has been outlined along strike for 3,280 m, can be as much as 200 m in width and extends based on current drilling to at least 440 m depth. Gold mineralization at Fekola is dominantly hosted within bedrock and occurs with fine-grained disseminated pyrite, commonly in association with high strain zones and fold hinges. High-grade mineralization is concentrated in a high-grade shoot (>2 g/t Au) that plunges shallowly to the north–northwest at 14°.

The mining operations use conventional open pit mining methods and equipment, using Owner-operator mining equipment and labour. Mining is based on a phased approach with stockpiling to bring high-grade forward and provide operational flexibility.

The proposed mine production schedule involves the movement of a total 74.4 Mt/a of mineralized material and waste to sustain processing of 7.5 Mt/a of high-grade mineralized material while stockpiling as much as 9.3 Mt of low-grade mineralization and 9.6 Mt of currently sub-economic mineralization.

The mine design is based on cutback widths of 200–250 m, minimum mining width of 40m on all benches except floor of ultimate pit with 25m, nominal road and ramp widths of 27 m and a ramp gradient of up to 10%.

Waste storage facility design is based on 10 m vertical lifts with 18º faces and 5 m berms, with facility location considerations based on minimising haulage, surface water drainage and area availability.

The treatment plant incorporates the following unit process operations:

• Single stage primary crushing with a gyratory crusher to produce a crushed product size of 80% passing (P80) of 150 mm;

• Crushed ore stockpile with a nominal 10,000 t live capacity to provide 16 hours of operation at design plant throughput. During extended periods of up to three days for primary crusher equipment maintenance, ore from the dead part of the stockpile is reclaimed by an excavator or dozer to feed the grinding circuit;

• Crushed ore from the stockpile is reclaimed by apron feeders positioned under the stockpile to feed the grinding circuit;

• The grinding circuit is a semi-autogenous grind (SAG)–ball mill/pebble crusher circuit (SABC) type, which consists of an open circuit SAG mill, pebble crusher for SAG mill discharge oversize and a closed-circuit ball mill to produce a P80 grind size of 75 µm;

• Quicklime from a silo is added onto the SAG mill feed conveyor along with the crushed pebbles. Sodium cyanide solution is added to the SAG mill feed chute to start the gold leaching process;

• Hydrocyclones are operated to achieve a cyclone overflow slurry density of 25% solids to promote better particle size separation efficiency. Following this, a leach thickener is used to increase slurry density to the leach circuit, minimise leach tank volume requirements, reduce overall reagent consumption, and separate gold dissolved by cyanide addition to the grinding circuit;

• Carbon columns (CIC) recover gold already dissolved in the grinding circuit. The leach thickener overflow stream is pumped to this carbon adsorption circuit;

• Leach circuit with six tanks to achieve the required 24 hours of residence time at design plant throughput. Carbon-in-pulp (CIP) circuit consisting of six stages is a carbon adsorption circuit for recovery of remaining gold dissolved in the leaching circuit;

• Zadra elution circuit with gold recovery to doré. The circuit includes an acid wash column to remove inorganic foulants from the carbon with hydrochloric acid. The single elution circuit is common for both carbon adsorption circuits;

• Carbon regeneration kiln to remove organic foulants from the carbon with heat. This piece of equipment is common for both carbon adsorption circuits;

• Cyanide destruction circuit using SO2 and air to reduce the weakly acid-dissociable (WAD) cyanide (CNWAD) level in the tailings discharge stream to an environmentally acceptable level;

• Tailings thickener to increase slurry density for water recovery prior to tailings discharge to the TSF.