Overview

Deposit type

• Orogenic
• Saprolite
• Vein / narrow vein

Summary:

The Fekola deposit, Cardinal Zone and Anaconda Area are hosted in Birimian Supergroup rocks within the eastern portion of the Paleo-Proterozoic Kédougou–Kéniéba inlier, which covers eastern Senegal and western Mali. They are considered examples of orogenic-style gold deposits.

The Fekola deposit is hosted by a moderate to steeply west dipping, folded sequence of marine meta- sediments of the Kofi group. The deposit has been subjected to greenschist facies metamorphism. Gold mineralization is associated with fine-grained disseminated pyrite and local pyrite veinlets. The Fekola deposit, including the Fekola North Extension, has been outlined along strike for approximately 3.5 km, up to 200 m in width and extending, based on current drilling, to at least 600 m in depth. The greatest continuity is observed within a high-grade (“HG”) shoot (>2 g/t Au) which plunges approximately 14° to the north–northwest in the south end of the Fekola deposit, flattening to about 5° around the Fekola North Extension area. The deposit remains open along strike and down plunge.

The Cardinal Zone is hosted in southwest-striking mudstones, siltstones, and diorite intrusions with bedding dipping 35-50°to the west. The host stratigraphy is intruded by late feldspar-porphyritic dykes. All rocks are metamorphosed to greenschist facies. Mineralization is hosted in a series of west- dipping, brittle–ductile shears that are moderately to strongly discordant to lithology contacts. A halo of pervasive silicification locally accompanies these veins within the mineralized portion of the shear zone. Gold is spatially associated with the quartz–carbonate veins and is strongly associated with the coarse grained pyrite (± pyrrhotite in mudstone host) in the wallrock to veins. Rare visible gold has been noted within the quartz–carbonate veins. Gold mineralization at the Cardinal Zone extends over 3.5 km along strike and up to 350 m vertically below surface, with the northern portion of the Cardinal Zone passing within 500 m of the Fekola resource pit. Mineralization is open at depth and along strike.

The Anaconda Area is hosted by both deeply weathered and unweathered Kofi group meta-sediments. Mineralized zones within saprolite and saprock can locally be traced into bedrock. Anaconda, Mamba, Boomslang and Cobra Zones have sulfide mineralization potential at depth. The Anaconda–Adder saprolite/saprock zone extends over 7,000 m along strike and up to 700 m wide at Anaconda and up to 275 m wide at Adder, with thickness ranging from 2 to >40 m thick, averaging 25 m true thickness. Saprolite/saprock mineralization at the Mamba Main and Mamba North zones extend 3,200 m along strike, up to 200 m wide and ranging from 20 to >120 m in thickness and averaging approximately 45 m true thickness.

The Seko, Koko, Disse and Diabarou deposits within the Dandoko Permit are examples of orogenic gold deposits. Mineralization is controlled by polyphase hydrothermal fluids that migrated along reactivated northeast-orientated shears. Dilation sites along either intersections with early north-northeast shears or along rheological contrasts control the high grade shoots. Gold is associated with albite, silica, sericite, ankerite-pyrite with minor tourmaline, chalcopyrite, and pyrite alteration assemblages within fresh rock. Gold mineralization at Seko 1 extends 1,400 m along strike, up to 65 m in width and extending based on current drilling up to 350 m in depth. Gold mineralization at Seko 2 extends 900 m along strike, up to 80 m in width and extending based on current drilling up to 330 m in depth. Gold mineralization at Seko 3 extends 1,460 m along strike, up to 60 m in width and extending based on current drilling up to 260 m in depth.

Mining Methods

• Truck & Shovel / Loader

Summary:

The Fekola Mine is a conventional open pit owner-operated mine and plant. Higher-grade material is sent to the plant and lower-grade material is stockpiled which will be processed later in the mine life. The project plan assumes seven years of mining and nine years of processing, including 2023. The ultimate pit is planned for development in a sequence of nine pit phases. The ultimate pit will be approximately 2.7 km long, 1.0 km wide and 430 m deep, with an overall strip ratio (waste to ore) of 9 to 1. Overall pit slopes vary by geotechnical domain, between 22–34º in saprolite and transition zones near surface, and between 41–47º in fresh rock.

The Cardinal Zone is a conventional open pit operation located within 500 m of the Fekola open pit. Long term planning studies of the Cardinal Zone are ongoing. Preliminary studies indicate the potential to add approximately 60,000 ounces per year over the next six to eight years, providing an ore supplement to the Fekola mill, based on existing Mineral Resources. Operating and design practices at the Cardinal Zone are expected to be similar to the Fekola Mine. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. The Cardinal Zone as currently defined is approximately 3.5 km long, and 0.6 km wide, and the current Mineral Reserve estimate is contained within a single small pit, approximately 900 m long and 300 m wide.

Production from the Bantako Nord Permit is expected to be a conventional open pit operation located approximately 20 km north of the Fekola mill. Long term planning studies of the Fekola Regional permits, including the Bantako Nord Permit and Menankoto Permit, are ongoing. Operating and design practices from the Fekola Regional permits is expected to be similar to the Fekola Mine. Preliminary studies indicate the potential to produce 80,000 to 100,000 ounces per year over the next six to eight years, hauled to and processed at the Fekola mill, based on existing Mineral Resources.

Mining operations are scheduled to work 365 days a year with reduced productivity during the rainy season, although it is assumed that mining operations will take place under wet conditions with borehole and in-pit de-watering programs in place. The equipment fleet is conventional for the industry (90 t and 180 t capacity rigid haul trucks and 150 t, 180 t, and 400 t class excavators) and provides relative flexibility as up to three pit stages will be mined simultaneously to mine waste and ore at different levels. Ore is transported from open pits to the run-of-mine (“ROM”) pad for direct tipping or stockpiling.

There are three waste rock storage facilities (“WRSF”) at the Fekola Mine, two located to the west and east of the open pit, and one located to the northwest of the Fekola pit, north of the existing tailings storage facility (“TSF”). Suitable mine waste is used for raises on the TSF which is located to the northeast of the pit. Construction of a second TSF will commence in 2023. Location considerations for WRSF and the TSFs were based on minimising haulage costs, sustainability impacts, surface water drainage, and area availability. An overall slope angle of 18° was used in the design of the WRSF faces, with 30 m berms located at 15 m vertical intervals.

Comminution

Crushers and Mills

Summary:

Ore Receiving and Crushing
ROM ore is tipped directly into either side of the ROM pocket. A rock breaker is installed to assist in breaking down oversize material retained above the gyratory crusher in the ROM pocket. Ore is crushed by the gyratory crusher and then withdrawn from the ROM discharge pocket by a variable speed apron feeder. The crushed ore is conveyed, via the stockpile feed conveyor, to the crushed ore stockpile.

Crushed Ore Stockpile
The crushed ore stockpile has a live capacity of approximately 10,000 t (equivalent to 11 hrs of mill feed at a nominal throughput rate of 7.5 Mt/a) and a total storage capacity of 57 hours.

Crushed ore is reclaimed from the stockpile, by three variable speed apron feeders. The feeders discharge onto the SAG mill feed conveyor which conveys the crushed ore to the SAG mill feed chute.

Grinding and Classification
The Fekola grinding circuit is a traditional SABC circuit, comprising a single, variable speed, SAG mill and a single fixed speed ball mill. The SAG mill operates in closed circuit with a pebble crusher, whilst the ball mill operates in closed circuit with hydro-cyclones. The product particle size exiting the grinding circuit (cyclone overflow) contains 80% passing 75 µm material.

Crushed ore, reclaimed from the stockpile, is conveyed to the SAG mill feed chute. Process water is added to the SAG mill feed chute, to control the in-mill pulp density. The SAG mill is fitted with discharge grates to allow slurry to pass through the mill and also relieve the mill of pebble build-up. The SAG mill product discharges to a single deck vibrating screen, for pebble sizing and dewatering.

Grinding media (125 mm balls) is added to the SAG mill via direct dump onto the SAG mill feed conveyor. SAG mill discharge screen oversize is conveyed to a pebble crushing circuit. Undersize from the discharge screen flows by gravity to the cyclone feed pump box, where it combines with the discharge slurry from the ball mill. The slurry is then pumped to the cyclone cluster by one of two (duty/standby) variable-speed cyclone feed pumps. Process water is added to the cyclone feed pump box for cyclone feed density control.

The cyclone cluster overflow flows by gravity through a metallurgical sampler then onto two linear trash screens in a parallel configuration. Trash screen undersize is directed to the leach thickener feed whilst trash screen oversize is discharged to trash dewatering screens for trash collection and disposal. Slurry from the cyclone underflow launder, is returned to the ball mill feed chute with optional underflow slurry recycle to the SAG mill. Ball mill discharge passes through the ball mill trommel prior to discharging to the cyclone feed pump box. Reject oversize material, from the ball mill trommel screen, is collected within the ball mill scats bunker.

Pebble Crushing
Oversize from the SAG mill discharge screen is conveyed to the pebble crusher feed bin, via a series of belt conveyors. Two self-cleaning belt magnets are positioned in the conveying circuit to remove any scrap metal and steel media which can potentially damage the pebble crusher.

Pebbles pass under a metal detector, then discharge into the pebble crusher feed bin. The feed bin provides surge capacity ahead of the pebble crushers and allows a controlled feed to be presented to the crushers which provides a choke-feed condition and consistent power draw. Should the pebble crushers not be operational, or the metal detector detect tramp metal, a diverter gate ahead of the feed bin allows pebbles to bypass the bin and crushers and feed directly to the pebble crusher discharge conveyor.

Pebbles are withdrawn from the pebble crusher feed bin, by variable speed vibrating feeders. Two pebble crushers are installed, and operate in a duty/standby arrangement. The pebble crusher discharges crushed pebbles directly onto the pebble crusher discharge conveyor which in turn returns the crushed pebbles to the SAG mill feed conveyor.

Processing

• Crush & Screen plant
• Carbon re-activation kiln
• Smelting
• Agitated tank (VAT) leaching
• Carbon in column (CIC)
• Carbon in pulp (CIP)
• Carbon adsorption-desorption-recovery (ADR)
• Elution
• Filter press
• Solvent Extraction & Electrowinning
• Cyanide (reagent)

Summary:

The mill uses a conventional flowsheet, consisting of: single-stage primary crushing; a SABC grinding circuit; leach feed thickening with thickener overflow treated through a carbon in column circuit; leaching followed by CIP adsorption; elution and gold recovery to doré; and cyanide destruction, tailings thickening and disposal circuits. The primary gyratory crusher and SABC grinding circuit include a ball mill in closed circuit with cyclones to achieve the final product size. The cyclone overflow stream flows by gravity to three linear trash screens operating in parallel ahead of a leach thickener. NaCN and lead nitrate are added to the SAG mill feed to start the gold leaching process. The leach thickener overflow solution is pumped to carbon columns to recover gold already dissolved in the grinding circuit. The thickened slurry is pumped to a leach circuit and then additional NaCN along with lead nitrate and oxygen are added for further gold leaching. A CIP circuit will adsorb dissolved gold onto activated carbon. A pressure Zadra elution circuit is used to recover gold from loaded carbon to produce doré. A cyanide destruction circuit using SO2 and air reduces the weak acid dissociable cyanide level in the tailings stream to an environmentally acceptable level. The tailings stream is thickened to recover water before being pumped to the TSF. Key consumables include reagents, water, and air services.

The LoM plans are based on a nominal plant throughput rate of 7.5 Mtpa, which can support a planned throughput rate of 9.0 Mtpa, including saprolite processing, and up to 9.2 Mtpa with detailed planning and optimization.

The treatment plant design 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 tonne live capacity to provide 20 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 normally reclaimed by apron feeders positioned under the stockpile to feed the grinding circuit.

• The grinding circuit is a 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. Subsequently, a leach thickener is included 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) are included to recover gold already dissolved in the grinding circuit. The leach thickener overflow stream is pumped to this carbon adsorption circuit.

• Leach circuit with five 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 WAD Cyanide 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 tailings storage facility.

Water Supply

Summary:

Water for the Fekola Mine is sourced from pit groundwater, surface water (direct precipitation and rainfall runoff) storage, dedicated bore holes for potable water use at both the process plant and the accommodation camp, and water pumps at the Falémé River in the event that site water quantity or quality requirements are not met as anticipated by the pit dewatering bore holes and surface water (direct precipitation and run-off) storage.

The process plant uses process water, reclaim water, fresh water, treated water, gland water and potable water. Any shortfall of process water is made up, preferentially, from water contained within the reclaim water pond. If insufficient water is available within the reclaim water pond, fresh water is used for make up to the reclaim water pond. An event pond, which holds any overflow from the process plant and stormwater collected from around the process plant, is pumped to the reclaim pond when necessary.

Process water predominantly consists of leach thickener overflow and reclaim water make-up. Reclaim water predominantly consists of tailings thickener overflow, decant return water from the TSF and fresh water make-up. Fresh water for potable water use is sourced from dedicated potable water bores.

Fresh water for the process plant and mining operation is sourced from active pit dewatering bores. The location of the pit dewatering bores changes as the mining progresses through the stages of the mine life. The bores pump predominantly to the fresh water storage pond, and if required, the bores can pump to the fresh water tank.

Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Development Manager	Grant Jukawics		Aug 15, 2023
Maintenance Planner	Mahamadou Hassim Diallo		Aug 15, 2023
Maintenance Planner	Ali Coulibaly		Aug 16, 2023
Mechanical Maintenance Superintendent	Matt Wesson		Aug 15, 2023
Mill Manager	Daniel Clark		Aug 15, 2023
Project Manager	Benjamin Scott		Aug 15, 2023