Overview

Deposit type

• Orogenic
• Saprolite
• Vein / narrow vein

Summary:

The Fekola Complex is hosted in Birimian Supergroup rocks within the eastern portion of the Paleo-Proterozoic Kédougou–Kéniéba inlier, which covers eastern Senegal and western Mali. The deposits are considered to be examples of orogenic-style gold deposits.

The Fekola deposit is hosted by a moderate to steeply west-dipping, folded sequence of marine metasediments of the Kofi group. The deposit has been metamorphosed to greenschist facies. Gold mineralization is preferentially hosted in very fine-grained, disseminated pyrite, within pervasively dolomitized sediments or diorite, and is focused within highly strained shear zones. Pyrite veinlets are also observed, locally folded within these same shear zones. The Fekola main mineralized shoot extends for over 3 km, along a north-northwesterly strike direction. The shallow portion of the mineralization extends towards the north to the area known as FNE, for a total near surface mineralized trend of over 8 km. The main Fekola shoot is 35-230 m wide, including high-grade (“HG”) shoots that range in width from 8-75 m. The main low-grade shoot is 80–500 m in height, and becomes deeper towards north, including a HG ore shoot that ranges from 80–200 m in height. The mineralization dips steeply to the west, and narrows to the north, where mineralization becomes more tightly constrained above the footwall phyllite contact. The widest and highest-grade portions of the Fekola mineralization are associated with a flexure in the dip angle. The mineralization has been tested on all directions, although it may remain open at depth with the formation of sub-parallel deeper shoots. The deepest mineralized interval intersected by drilling to date is 550 m below surface.

The Cardinal Zone is hosted by 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. Mineralization is hosted in a series of west-dipping, brittle–ductile shear zones that are moderately to strongly discordant to lithology contacts. A halo of pervasive silicification locally accompanies veins in the mineralized portion of the shear zone. Gold is spatially associated with quartz-carbonate veins and is strongly associated with coarse grained pyrite (± pyrrhotite in mudstone host) in the wallrock to veins. Rare visible gold has been noted within the quartz-carbonate veins. The Cardinal Zone comprises two principal zones of mineralization: Cardinal and FMZ, the latter being a reference to the structure that has historically been referred to as Fadougou Main Zone. To date, drilling has defined mineralized structures over 3.8 km along strike, with the northern portion of the Cardinal Zone, passing within 500 m of the Fekola Open Pit. The horizontal footprint is up to 400 m wide, and mineralization has been intersected by drilling down to 360 m below surface. The Cardinal mineralization includes multiple 2-30 m wide anastomosing structures, collectively forming a 20-50 m wide zone.

The Anaconda Area is hosted by folded meta-sediments and mafic intrusions of the Kofi Series. The metasedimentary sequence is comprised of phyllite, sandstone, siltstone, local mass flow breccia and marls and is intruded by various diorite dykes and sills. Tectonic brecciation of lithologic units and pervasive albitization are common. Brecciation and albitization are concentrated within and along shear zones in the Anaconda Area, as the result of a protracted deformation history; the overlying regolith, including laterite (duricrust), saprolite and saprock, ranges in thickness from several metres, to locally over 100 m thick and conceals fresh rock across the entire Anaconda area. Mineralized zones within saprolite and saprock can locally be traced into bedrock. The Anaconda, Mamba, Boomslang and Cobra deposits have sulfide mineralization potential at depth. Gold mineralization is associated with pyrite, which can occur in zones of network replacement sulphide, and as discrete quartz-carbonate- pyrite and brecciated veins.

Anaconda is the westernmost of the deposits comprising the Anaconda Area. The mineralized footprint in the saprolite horizon extends for 6.5 km along strike and is up to 1 km wide in the central portion of the deposit, narrowing at both ends. The saprolite thickness varies from 2 m to >140 m, averaging 37 m vertical thickness. Mineralization has been identified down to >200m below surface within discontinuous lenses but is commonly restricted to a shallower 100–150 m depth. The mineralized low-grade lenses vary from 10–100 m wide, commonly exhibiting 50 m wide stacked horizons. The Mamba deposit is located approximately 1.2 km northeast of the Anaconda deposit and extends over 3.8 km along strike, including a northeasterly-trending splay. The Mamba Main mineralization footprint is about 400 m wide, not including the eastern and northeastern splays which are 300 m towards the east. The deposit includes multiple south-plunging, steep westerly dipping ore shoots that are 10–80 m wide, locally widening to as much as 100 m in the saprolite. The Cobra deposit is situated approximately 2.6 km southeast of Mamba. It has been defined over a south–southwesterly strike length of 5.4 km, and a width of about 250 m, including a western sub-parallel mineralized trend. The main strand of the Cobra deposit is a planar and continuous, sub-vertical to west dipping structure, 4–30 m wide, drilled down to a depth of 350 m below surface. Both oxide- and sulphide-related gold mineralization is present at Cobra, with mineralized saprolite extending to a depth of approximately 130 m below surface, with 45 m average vertical thickness. The Taipan deposit is located at the southernmost end of Cobra, on a north-northwest trending structure that may crosscut that which hosts the Cobra deposit. Taipan has been defined over a strike length of approximately 6.4 km, bending to a more north–south trend in the northern 2.3 km of the deposit’s known extent. Taipan has a horizontal footprint maximum of about 250 m, including the main structure, which is roughly tabular, dips to the west–south-west, and ranges from 5–35 m in width. It has been intersected by drilling to a depth of 220 m below surface.

The Dandoko Area is underlain by sedimentary and to a lesser extent, igneous rocks of the Kofi Series, though much less deformed and altered than those underlying the Fekola Mine and Anaconda Area. The Dandoko Area comprises three discrete mineralized structures, which host the Seko 1, 2, and 3 deposits. The Seko deposits are underlain by a turbidite succession and platform carbonate rocks. A post-mineral dolerite sill intrudes the sedimentary package, as does a granite intrusive body. Except for the dolerite sill, most rock types exhibit overprinting breccia textures. The breccias are interpreted to be a significant control on the distribution of gold mineralization in the bedrock and its weathered equivalents. The Seko deposits have an extensive and well-developed lateritic regolith profile, with weathering observed to over 200 m below surface in certain locations. Gold mineralization is both sulphide- and oxide-related and is localized in a moderately east-dipping zone at Seko 1 and in subvertical zones at Seko 2 and Seko 3. Each of the zones strikes to the northeast. The Seko 1 deposit is about 1.4 km long, and ranges in thickness from 15-35 m, averaging 25 m. Seko 1 has been drill-tested to about 350 m vertical depth. The overall mineralization strike length at the Seko 2 deposit is about 900 m, of which approximately 450 m of strike is well mineralized and forms the basis of the Mineral Resource estimate for this deposit. The mineralization thicknesses range from 40-80 m, averaging 60 m. Seko 2 has been drill-tested to about 320 m vertical depth. The overall mineralization strike length at the Seko 3 deposit is about 1.1 km, of which approximately 700 m of strike

Mining Methods

• Truck & Shovel / Loader

Summary:

Mining operations at the Fekola Complex use, or will use, conventional open pit mining methods and equipment. An Owner-operator mining equipment and labour strategy is executed at the Fekola Open Pit and Cardinal zone. A local contractor is planned to be used for mining of the Anaconda, Mamba, and Seko deposits. Mining is based on a phased approach with stockpiling to bring high-grade mineralization forward in the mine plan, and provide operational flexibility. Mining assumptions for the Anaconda, Mamba, and Seko deposits assume that the Bantako Nord, Menankoto Sud and Dandoko exploration permits can be converted to exploitation licences.

The Fekola Complex base case mine production schedule involves the movement of a total 111 Mt/a of ore and waste to sustain processing of 9.0 Mt/a of ore, while stockpiling as much as 13.4 Mt of low-grade material. 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.

Fekola Open Pit
The Fekola Open Pit is a conventional open pit owner-operated mine and plant. Higher-grade material is sent to the plant and lower-grade material is stockpiled to be processed later in the mine life. The Mineral Reserve based project plan assumes six years of mining and seven years of processing, including 2024.

The approximately 400 m deep ultimate pit is planned for development in a sequence of nine phases. Phases 1 to 5 are mined-out, phases 6 and 7 are partially mined out, and phases 8 and 9 remain in full as of December 31, 2023.

The staged pit development will also mitigate the geological, geotechnical, and economic risks for the operation, considering the 2.7 km length of the proposed Fekola Open Pit. The design of the future pit stages during the operations, in particular the last two stages, can be progressively adjusted depending on the operational experience, exposed ground conditions, and changes in economic conditions.

The Fekola Open Pit design is based on cutback widths between 250–450 m as guided by Whittle analysis, with a minimum mining width of 40 m on all benches except the floor of the ultimate pit, where the widths will be 25 m. Nominal road and ramp widths of 27 m were used. The lowermost benches of phases were designed with single ramp access. The ramp gradient was designed up to 10%.

The cutbacks must be accessed through temporary ramps in the initial stage of development from the surface. These temporary ramps may be mined after acting as safety berms between the successive cutbacks mined at different levels. The remaining ramps on the final pit walls will act as geotechnical berms (i.e. wider berms to limit the inter-ramp slope angle) to form a “stacked” slope design.

A minimum mining width of 25 m was adopted for the floor of the ultimate pit design. The temporary floors of the pit stages were designed with a wider interval of 40 m so as to not constrain the mining equipment unnecessarily, as these floors would be mined in the subsequent pit stage.

Cardinal Deposit
The Cardinal Zone is a conventional open pit operation located within 500 m of the Fekola Open Pit. Cardinal operations are underway and will continue for another four years (including 2024) to provide an ore supplement to the Fekola mill. Operating and design practices at the Cardinal Zone are similar to the Fekola Open Pit. The Cardinal Zone as defined is approximately 3.5 km along strike, and 600m wide.

There will be seven individual pits that complement feed from the Fekola Open Pit. Pit E, Pit S, Pit A and Pit C are partially mined out as at December 31, 2023.

The pits are accessed through individual permanent ramps on the final pit walls that will act as geotechnical berms for the ultimate pits. The Cardinal pit design was based on small pits that vary in widths from 140–270 m as guided by Whittle analysis, with a minimum mining width of 30 m on all benches except the floor of the ultimate pit, where the widths will be 18 m. Nominal road and ramp widths of 27 m were used. The lowermost benches of phases were designed with single ramp access. The ramp gradient was designed up to 10%.

Anaconda Area
Production from the Anaconda Area, consisting of the Mamba and Anaconda deposits, will be from a conventional open pit operation located approximately 20 km north of the Fekola mill. A sequence of four pits is planned, consisting of Anaconda A, Mamba A, Mamba B and Mamba C. Mining is planned to commence with Mamba A in Q4, 2024.

The pit design is based on open pit widths of between 140–450 m as guided by Whittle analysis, with a minimum mining width of 30 m. Nominal road and ramp widths of 27 m were used to allow for the use of 90 t class haul trucks when mining conditions are suitable, otherwise widths of 18 m were used. The lowermost benches of phases and pits were designed with a single ramp access. The ramp gradient was designed up to 10%.

Overall pit slopes vary by geotechnical domain, between 27–38º in saprolite and transition zones near surface, and up to 51º in fresh rock. The feed will be a combination of oxide and sulphide ore. Oxide ore makes up approximately 55% of the ounces in the Anaconda production plan.

Dandoko Area
Production from the Dandoko Area will be from a conventional open pit operation located approximately
31 km east of the Fekola mill. A sequence of three pits is planned, consisting of Seko 1, Seko 2 and Seko 3. Mining is planned to commence with Seko 1 in 2027.

The pit design was based on small pits that vary in width from 110–430 m as guided by Whittle analysis, with a minimum mining width of 30 m. Nominal road and ramp widths of 19 m were used. The lowermost benches of phases were designed with single ramp access. The ramp gradient was designed up to 10%.

The deepest pit will reach 140 m. Overall pit slopes vary by geotechnical domain, between 27–38º in saprolite and transition zones near surface, and up to 51º in fresh rock. The feed will be a combination of oxide and sulphide ore. Oxide ounces make up approximately 75% of the ounces in the Dandoko production plan.

Road and Ramp Design Criteria
A nominal ramp and road width of 18 m was designed where a Volvo articulated truck (40 t) fleet is in operation. A nominal 27 m ramp and road width were used where a Caterpillar 777 truck (90 t) fleet is in operation. A 35 m road width was designed where a Caterpillar 789 truck (180 t) fleet is used. These widths include drainage and safety windrows, and allow for dual lane truck operation in the mine design.

A ramp gradient of up to 10% was used for both–single- and dual-lane ramps. A smaller 18 m ramp was used for the Anaconda and Dandoko Areas, where the pits were relatively small and entirely in oxide material. A wider, 27 m ramp was used for larger pits that will have significant fresh rock. The largest, 35 m ramps are used in the Fekola pit where the stripping ratio is high to expedite exposure of higher-grade zones.

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 hydrocyclones. 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 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.

Leach Thickening
Trash screen undersize flows by gravity directly to the leach thickener feed box, where flocculant is added to aid with particle settling. Overflow solution from the leach thickener flows by gravity to the leach thickener overflow tank and is then pumped to the carbon in columns circuit. Underflow from the leach thickener is pumped to the leach feed distribution box. A thickener recycle pump is included to improve thickener operational flexibility when running, and ensure compaction of the thickener bed does
not occur if the thickener is off-line for a plant shutdown.

Carbon in Columns Circuit
Leach thickener overflow is pumped to the CIC circuit. The CIC circuit recovers gold in solution from the grinding circuit, then pumps the discharge solution, which is cyanide bearing solution, to the process water tank for reuse in the grinding circuit.

Using a common carbon transfer pump, carbon is transferred forward throughout the columns counter-current to the flow of solution. A second carbon transfer pump recovers carbon to the loaded carbon recovery screen for gold carbon desorption. Approximately twice per week, loaded carbon from the first carbon column is pumped by the second carbon transfer pump, to the loaded carbon recovery screen. The screen solution underflow flows by gravity to the carbon column of origin whilst the loaded carbon flows by gravity to the acid wash column.

Regenerated carbon (or fresh carbon) is added to the CIC circuit, from the carbon regeneration circuit. The regenerated carbon (or fresh carbon) is pumped, to the CIC circuit, via the CIC carbon sizing screen. The sizing screen removes excess water and carbon fines. The dewatered carbon discharges into the last, online, CIC tank with excess water and carbon fines directed to the carbon fines collection hopper for further removal from the circuit.

Leach Circuit
Leach thickener underflow is pumped to the leach feed distribution box. The slurry from the leach feed distribution box flows by gravity to the first leach tank.

The leach circuit consists of seven mechanically agitated, leach tanks operating in series. This equates to a residence time of over 21 hrs at a design feed rate of a nominal 7.5 Mt/a. Each leach tank has a live volume of 3,900 m³.

Carbon in Pulp Circuit
The CIP circuit consists of six, mechanically agitated, CIP tanks operating in series. This provides a residence time of about 5 hrs for a plant throughput of a nominal 7.5 Mt/a. Each CIP tank has a live volume of 1,100 m³.

The leaching circuit dissolves the remaining gold in solid and the CIP circuit recovers this dissolved gold in solution by carbon adsorption. Activated carbon is retained in each of the CIP tanks by an inter-tank screen.

As the slurry flows by gravity through the CIP tanks, the carbon is advanced countercurrent to the slurry flow. Carbon advancement is achieved by the CIP carbon transfer pumps, of which there is one transfer pump per CIP tank.

Approximately five times per week, loaded carbon from the first CIP tank is pumped to the loaded carbon recovery screen, where it is washed with spray water to remove excess slurry. The excess slurry (screen underflow) flows by gravity to the CIP tank of origin whilst the loaded carbon flows by gravity to the acid wash column.

Regenerated carbon (or fresh carbon) is added to the CIP circuit, from the carbon regeneration circuit. The regenerated carbon (or fresh carbon) is pumped, to the CIP circuit, via the CIP carbon sizing screen. The sizing screen removes excess water and carbon fines. The dewatered carbon discharges into the last, online, CIP tank with excess water and carbon fines directed to the carbon fines collection hopper for further removal from the circuit.

Slurry discharging the last CIP tank flows by gravity to the CIP carbon safety screen. The carbon safety screen captures and recovers any carbon exiting the CIP circuit. The safety screen oversize reports to a fine carbon skip bin while the undersize is pumped to the cyanide destruction feed box.

Acid Wash, Elution, Electrowinning and Gold Room
The Fekola desorption circuit consists of separate acid wash and elution columns. A cold acid wash is used for removal of inorganic foulants. Following acid wash, gold is eluted from the carbon, using a Pressure Zadra elution process. An average daily carbon movement of 14 t satisfies the required carbon movements for both the CIC and CIP circuits.

Carbon Regeneration
After elution, the carbon is hydraulically transferred from the elution column to the carbon regeneration circuit.

Cyanide Destruction
CIP tailings are pumped to the cyanide destruction tank where cyanide destruction is achieved using the SO2/air process.

Tailings Thickening and Disposal
Slurry from the cyanide destruction circuit is pumped to the tailings thickener feed box. Flocculant is added to the tailings thickener to enhance the settling properties of the solids. Overflow from the tailings thickener flows by gravity to the reclaim water pond. Tailings thickener underflow is pumped to the tailings pump box. Two tailings pumps, in series configuration, pump to the TSF and discharge the slurry via spigots around the circumference of the dam. Water from the surface of the TSF is recovered from the decant system and pumped back to the reclaim water pond. Underdrainage and seepage from around the TSF drainage system is pumped into the TSF for recovery by the decant return water pump.

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		Jul 26, 2024
Equipment Maintenance Planner	Keita Hawa		Jul 26, 2024
Exploration Manager	Toure Abdou		Jul 26, 2024
Maintenance Planner	Mahamadou Hassim Diallo		Jul 26, 2024
Mechanical Maintenance Superintendent	Matt Wesson		Jul 26, 2024
Mill Manager	Daniel Clark		Jul 26, 2024
Mill Superintendent	Moctar Diallo		Jul 26, 2024
Procurement Manager	Tatiana Antonovich		Jul 26, 2024
Safety Manager	Lassine Coulibaly		Jul 26, 2024