The Loulo and Gounkoto deposits can be classified as typical shear hosted Birimian style mesothermal gold deposits.

The Loulo project area is characterised by a sequence of sandstone, limestones and greywackes which are truncated by three major north to NE trending shear zones. Two major mineralised bodies have been discovered within the Project area, Gara and Yalea. Several other satellite deposits (Baboto, Gara West and Loulo 3) are also present.

Yalea is located in a north-south striking, steeply dipping package of metasedimentary rocks. Host lithologies at Yalea (from west to east) comprise of quartzite/grey in the hanging wall, with tectonic breccias in the north. Immediately above the main body of mineralisation is thin (0 m to 5 m) sequence of banded schistose greyish limestone, with alternating white and grey calcitic layers and dark grey to black phyllite units. The main mineralised body is a hydrothermally brecciated argillaceous pink quartzite that becomes more argillaceous (and less altered) towards the footwall. A higher grade ‘Purple Patch’ zone is observed in a dilatational strain transfer zone formed as the dip of the mineralised package steepens forming hydraulic breccias. The footwall package is a thick sequence of argillaceous quartzite and black sandstone. This sedimentary package is intruded locally by thin (0.1 m to 2 m) acid intrusives of mostly granitic composition.

At Yalea, the main mineralised body is a hosted by the north-striking Yalea Shear, where it is intercepted by the Yalea Structure. The Yalea Shear is a brittle-ductile, north-south striking, mineralised fault that transects the Yalea Structure, which is a complex, of north to NNE striking shear zones.

Gold mineralisation is situated between a hanging wall and footwall shear within the reactivated 2 km portion of the predominant Yalea – Baboto structure. The mineralisation dips to the west at 65° for the initial 200 m to 300 m vertically after which the structure steepens and becomes sub vertical.

Yalea mineralisation, remains open at depth and to the south with potential for significant highgrade extensions. To the south of the ‘Purple Patch’ zone the Yalea Shear forms a subhorizontally plunging transfer zone where the competency contrast of the footwall argillaceous quartzites (SQR) contact causes a transfer of strain associated with normal movement. Consequently, this transfer creates dilatational hydraulic breccias with the potential to host significant high-grade extensions.

Gara is located 6 km NNW of the Yalea deposit and is hosted within 800 m long tourmaline sandstone/greywacke unit which outcrops on surface as black quartzite forming small (10 m) topographic highs. The host lithologies are (from west to east): chemical (limestone or carbonate altered) sediments and alternating argillitic and quarzitic bands (argillaceous quartzite or SQR) in the hanging wall, mineralised quartz tourmaline (QT) ranging from 5 m to 20 m thick (average 15 m) and a coarse to medium grained greywacke unit in the footwall. The sedimentary package is also crosscut by three unmineralised late EW dolerite sub-horizontal dykes that plunge shallowly from north to south.

Gold mineralisation is strata bound and hosted predominantly within the quartz-tourmaline sandstone unit which is enveloped within footwall greywackes and hanging wall schistose sandstone. Higher gold grades typically occur where the veining is most intense and the range of vein orientation more complex and are mostly in association with carbonate-pyrite. Mineralised veins also contain minor chalcopyrite, scheelite, rare earth element phosphates and nickeliferous sulphides.

Baboto is a shear hosted deposit situated along a north-south striking shear structure located approximately 14 km NNE from the Yalea deposit. This 5 km long structure contains the Baboto South, Centre and extends to Baboto North on a neighbouring permit.

Baboto is dominated by a thick sequence of metasediments consisting of siltstone, quartzite, greywacke, polymictic conglomerate, and structural breccias with intercalated, strongly sheared argillite. Late cross-cutting mafic intrusives transgress all lithological units.

The strike of the bedding varies from NNE to WNW and the dip varies from steeply east to steeply west. The main shear zones are vertical to steeply west dipping at Baboto South and sub vertical in Baboto Centre.

Gold mineralisation is mainly associated with the finely disseminated pyrite occurring in the brittleductile shear breccias. These zones generally have a lensoidal shape defined by a series of subparallel N-S shears that follow the lithological contacts between the conglomerate, quartzite, and greywacke. The tabular pyrite or arsenopyrite does not correlate with gold mineralisation, while the fine acicular arsenopyrite is often associated with the mineralised zones. The hanging wall and footwall to the mineralisation are in general strongly foliated rock. The geological model consists of multiple sub parallel dilation structures hosting mineralised zones, which have a lensoidal shape.

The low-grade envelope is probably related to the dilation created by the 202° to 220° early sinistral shear. High-grade (4.4 g/t Au to 12.2 g/t Au) en-echelon quartz veins (oriented 240° and dipping 40° to 85° NW and bounded within N-S trending shears) might be explained by the reactivation of the early 202° to 220° sinistral shear by the later dextral movement.

Loulo 3 is located 4 kilometers north-northeast of the Yalea mine. Loulo 3 consists of four mineralized zones: a north-northwest trending main zone (“MZ1”), which is situated on the Loulo 3 structure and is transected by the north-northeast striking main zone (“MZ2”), which is situated on the Yalea structure, and two sub- parallel northwest striking footwall zones. The MZ2 mineralisation has an overall strike length of 1.8 km, ranges in thickness between 6 m to 12 m. Both MZ1 and the FW zone have smaller dimensions, being 580 m in strike, 5 m to 7 m thick and 200 m in strike, with 5 m thickness, respectively. The stratigraphy at Loulo 3 (inclusive of Loulo 2) comprises three major lithological sub units, which from east to west include: the hanging wall (“HW”) package (subunits HW1 to HW5), the host package (subunits HP1 to HP4), and the footwall (“FW”) package (subunits FW1 to FW2). The mineralization in Loulo is hosted in the HP4 subunit of the Main Sandstone package with a dominant vein-mineralization in Loulo 3 is hosted in the HP4 subunit of the Main Sandstone package with a dominant vein-hosted mineralization style within MZ1 or quartz-tourmaline veins in MZ2. These vein arrays locally transition into bedding-parallel hydrothermal breccias with local semi-massive to massive pyrite, which can also include arsenopyite and hematite, and form the high-grade shoots within the Loulo 3 deposit.

Gara West is located in the hanging wall sequence approximately 400 m west of the Gara pit and is characterised by predominantly shear and breccia hosted mineralisation within a medium to coarse grained sandstone unit that is variably altered with tourmaline, chlorite, and silicacarbonate. The sandstone hosts four mineralised lodes striking NNE and dipping moderately westward. All mineralised zones are sub-parallel, striking NNE and dipping steeply westward.

The gold mineralisation is strata bound and hosted in strongly developed quartz carbonate vein arrays as well as associated disseminations and hydrothermal breccias within pink quartzite. The mineralisation exhibits a pinch and swell geometry at the scale of the deposit and have greater continuity along strike than at depth. Higher grades are associated with increasing intensity of quartz-carbonate vein development, carbonate-hematite-goethite alteration, and intensity of brecciation.

The Yalea, Gara and Gounkoto underground mines are all currently in operation and are accessed via portals located in the open pits and a box cut.

Development of Gounkoto underground commenced in 2020 with the aim of mining the crown pillar under the North Pit during the second quarter of 2023. It adds high-grade ounces to Loulo-Gounkoto from 2023. The mining method for Gounkoto underground consists of long-hole bench stoping with backfill.

The declines were originally developed as twin declines. One decline containing a conveyor and the second decline is used for mobile equipment access. The lower part of the mines has been developed as single declines with truck haulage up to crushers which feed ore and waste onto the conveyors.

Three mining methods are used at the Yalea and Gara underground mines. They are long hole transverse open stoping; long hole longitudinal retreat open stoping; and stoping under rock fill (SURF). SURF mining is planned to be introduced in the weathered areas of Yalea South Upper.

The SURF method is planned for the portion of Yalea South Upper that has weathered transition or saprolite present in the mineralised zone, or the immediate hanging wall. The method will be used is expected to provide a more consistent production in the less competent ground.

From an operational perspective SURF is very similar to longitudinal sub level caving (SLC). The exception is that in SURF waste rock is tipped into the stope to fill mined voids and prevent caving of the hanging wall. In contrast SLC works by the hanging wall caving to fill the mined void.

In 2014 paste fill plants were commissioned. The paste fill plants at each of the mines produce a mixed paste / aggregate fill. With the introduction of paste fill the lower areas of the mines are being mined using an underhand (top down) long hole stoping method which retreats to central accesses in an echelon format. Panels are 50 m long, mined as single level stopes (25 m high) and filled with cemented paste fill. The paste fill is exposed by the mining of both the panel below and the next panel on the same level. Transverse long hole open stoping is used in the wider (>15 m wide) parts of Yalea North. Transverse stopes are 15 m to 30 m along strike and mined from hanging wall to footwall.

Run of Mine ore from the shafts and Gounkoto operations are blended using detailed source analyses to provide a blend of ore to the plant for treatment, meeting the plant operating specifications. The ore is crushed in three stages of crushing to provide a suitable product for feed to the primary mill. Soft ore is fed to the mineral sizer, followed by ball milling. The mill products are classified using hydrocyclones, returning the course material underflow to the grinding circuit. The cyclone overflow is thickened to a suitable underflow density and pumped to the CIL plant.

• Crushing – three stage crushing for the hard rock sulphide ores and a single stage roll toothed crusher for the soft weathered oxide ores.
• Milling – one primary mill (7 MW); two identical single stage ball mills (4.5 MW), one scat conveyor system is inserted to return all mills scats back to primary mill via a cone crusher.

Crushing – Hard Ore
Hard rock is delivered to the tipping bin. Tipping can be completed from two directions.

The hard rock crusher plant consists of a primary gyrator crusher (FFE Minerals 1,300 mm by 1,750 mm) driven by a 450 kW electric motor. A tramp iron magnet is installed over the product conveyor to remove steel. A metal detector trips the conveyor if metal is detected.

The primary crusher operated at a rate of 700 tph, feeds the secondary crushers which operate in open circuit and then the tertiary crushers which operate in closed circuit. An additional metal detector is installed on the feed to the tertiary crushers

The secondary circuit consists of two Sandvik CS6800 Hydrocone crushers and the tertiary circuit consists of four H6800 Hydrocone crushing units, all are powered by a 315 kW electric motor. The secondary and tertiary crushers are housed in separate buildings connected via transfer conveyors.

The final product from the tertiary crushers discharges onto a reclaim ore stockpile, via a conveyor system, and has a live capacity of about 40,000 t and a total of approximately 115,000 t. This is the feed to the SAG mill.

Crushing - Soft Ore
A separate facility exists to crush the soft ore when it is available. The soft ore crushing consists of a tooth roll crusher (MMD 625 - 3 tooth) driven by a 250 kW electric motor. This feeds a separate stockpile area and the roll crusher product is fed directly onto the ball mill conveyor feed.

Grinding and Classification
The milling section produces a leach feed with approximately 75% passing 75 microns. The milling circuit comprises of a SAG mill operating as the primary mill (6.1 m dia. and 9.5 m EGL and installed motor power of 7,000 kW to be upgraded to 8,000 kW) operating in open circuit. The oversize or scats are re-handled to the stockpile and re-crushed. The primary mill discharge feeds two parallel single stage overflow type ball mills (5.5 m dia. by 8.0 m EGL) with a power rating of 4,500 kW each, operating in closed circuit with a dedicated cluster of twelve 250 mm hydrocyclones of which eight are typically in use.

An additional High Pressure Grinding Roll (HPGR) has been installed to treat scats at a rate of 100 t/h.

The Loulo processing plant uses a CIL gold extraction process with a throughput capacity of 4.8 million tonnes per annum.

Since 2014 multiple optimisation projects have been undertaken, resulting in increased throughput and improved recoveries.

The upgraded process plant remains a conventional crushing, milling, gravity, CIL, and tailings disposal circuit. However, the gravity circuit has been taken off-circuit since September 2017.
The upgraded process plant remains a conventional crushing, milling, gravity, CIL, and tailings disposal circuit.

The process plant uses the following circuits:

• Crushing.
• Milling.
• Gravity - four centrifugal primary concentrators followed by two intensive leach reactors to treat primary concentrates (the gravity circuit has been taken off-circuit since September 2017).
• CIL recovery process.
• Zadra elution process.
• Electrowinning.
• Tailings pumping/deposition split ........