The Houndé deposits are shear-zone hosted orogenic gold deposits as supported by occurrence of sulphide-gold mineralisation in deformed, quartz carbonate-sulphide(-gold) veined and strongly metasomatised greenstone wall rocks.

A strong, northeast-trending, dextral shear zone cuts through the Houndé area. This shear zone lies approximately three kilometres west of the Vindaloo Zone and has a very sharp western edge, as defined by the magnetic data. The eastern edge of the structure is not well defined; however, magnetic data suggests that the shear zone may be four to six kilometres wide. To the east of this strong structure, shearing is focused along unit contacts with preference along the sediment volcanic, volcanic-gabbro and sediment-gabbro contacts. Sediment units are often strongly deformed and display local graphitic shear zones, gouge and healed breccias.

Vindaloo-Madras
The Vindaloo and Madras mineralised zones are predominantly hosted by altered magnetitebearing gabbro and to a lesser extent, andesitic volcanic rocks and sediments. The gabbrohosted zones range up to 70m in true thickness and average close to 20m true thickness in a section of the zone called Vindaloo Main. Volcanic- and sediment-hosted zones are generally less than five metres wide. The mineralised system is zoned with initial propylitic-style alteration along the outer edges of the system with the addition of chlorite and calcite stringers concurrent with the destruction of pyroxene, amphibole and plagioclase. In a poorly defined area, located to the west of the Vindaloo Main zone, the propylitic alteration is overprinted by a reddish hematitic alteration comprising disseminated hematite and hematite veinlets. Fine grained to millimetre-size pyrite crystals are associated with:
• Trace to 10%, up to 2cm wide, quartz veins (trace to 2% overall in mineralised zones);
• Pyrite-enriched haloes to the quartz veins; and
• Occasionally as disseminations within the host gabbro.

Bouéré
Gold mineralisation at Bouéré is associated with hydrothermal alteration zones and related quartz-carbonate veining, that appear to have occurred in protracted fashion throughout D1 and D2 deformations. The hydrothermal alteration at Bouéré evolved through D1 carbonatization (associated with no or very low-grade mineralisation) towards sericitization and silicification which occurred in pulsative fashion at a transitory late-D1 to syn-D2 stage of deformation (associated with significant mineralisation). Gold mineralisation is coeval with a progressive increase in the D2 deformation and a variably intense sericite – silica - carbonate (ankerite + calcite) ± albite alteration and zones of quartz – carbonate veining, both associated with sulphides dissemination in the altered rocks and in quartz veins. Gold veins were emplaced during a continuum of deformation between late D1 and syn-D2. High to very high gold grades are systematically associated with massive and/or laminated milky quartz (± carbonate ± albite) veins from one metre to multiple metres thick occurring in the silica-sericite-carbonate-sulphide alteration zones. Visible gold is nearly exclusively seen in theses quartz veins. Bouéré is characterised with low continuity of mineralisation over short along-strike distances and relay-type patterns of mineralisation resulting in fragmented/discontinuous lenses of mineralisation.

Dohoun
Gold mineralisation at Dohoun is intimately related to the shear zone along the western edge of the granodioritic intrusive. The gold is hosted in a brittle-ductile context with mainly pyritictype sulphides. The pyrite grain geometry is highly variable, though gold is generally associated with fine- to medium-grained pyrite in a hydrothermal alteration halo of sericite and quartzcarbonate veins. Richer and thicker mineralisation have been observed in volcanic rocks in direct contact with the intrusive where the shear zone thickens; however, the portion of the shear zone crossing the intrusive is low to medium grade (<2g/t Au).

Kari Centre
Kari Centre gold mineralisation is developed mainly within the volcanics, associated with whitish sulphide-sericite-albite alteration and fine disseminated pyrite at the hanging wall of the volcanic/sediments contact (N60° strike, dipping 45° to the northwest). The mineralisation is diffuse, locally high grade (>2g/tAu) but generally lower grade when hosted in the oxide horizon. In brittle sedimentary units, gold grades are structurally controlled, and locally can be high grade (>5g/tAu). These mineralised zones tend to occur in narrow, tension gash type structures. To date, neither visible gold nor arsenopyrite have been observed in drill cuttings.

Kari Pump
Gold mineralisation occurs at Kari Pump within a sheared reverse fault (D2) that appears to be folded and dipping from zero to 40 degrees to the west-northwest and northwest. The mineralisation exhibits good continuity over 1.3km along section and displays typical pinch and swell characteristics. The highest-grade areas of the quartz veins are typically thicker, and alternate with thinner vein areas which are typically lower in grade. Kari Pump gold mineralisation is associated with the pyrite occurring as veinlets and disseminated grains within the silica altered and quartz vein bearing host shear.

Kari West
Kari West hosts multiple stacked mineralised lenses that are sub-parallel to the lithological foliation, reflecting both strong structural and lithological control. The mineralised lenses trend in a general west to west-southwest direction with shallow and moderate dips to the north. The lenses vary in thickness from a few metres to locally tens of metres, displaying pinch and swell characteristics both along strike and down dip; structural observations suggest that the thicker zones may represent the intersection of two mineralised lenses with varying dip and strike characteristics. The gold mineralisation in Kari West is associated with pyrite occurring as veinlets and disseminated grains within the quartz veins and SASE and SEAL alteration.

The mining method at Houndé is conventional open pit mining including drilling, blasting, loading and hauling. Load and haul activities are owner operated. Contract service providers, SFTP Mining and African Explosives Limited ("AEL"), carry out drilling and blasting activities. Mining and processing of transition/fresh ore began in Q4 2017. In 2021, more oxide was mined as Kari Pump came into production. In 2022, Kari West will provide 1.0 Mt of Oxide mill feed to increase the oxide ratio for the total mill throughput from 40.1% in 2021 to 45.2% in 2022 and then oxide ratio drops to around 20 to 30% for the remaining LOM. Ore was mined from the Vindaloo Main, Vindaloo Central, Bouéré, Kari Pump and Kari West pits to feed the process plant in 2021. Bouéré pit was mined out to completion.

The in-pit material excavation is conducted by a fleet of eight Komatsu excavators consisting of one PC3000- 8R, three PC 2000-8R and four PC 1250-8R. Material haulage is done by 35 Komatsu HD785-7 rear dump trucks. Key items of the ancillary fleet are nine dozers, four 50 m3 water trucks and four motor graders. Ore mined is hauled to the ROM pad and near ROM stockpiles. Waste mined from the pit is hauled to the waste dumps and other projects requiring waste material for construction (i.e. tailing storage facility, haul roads etc.).

The ore control strategy targeting delineation of ore and waste uses RC holes piercing multiple benches. The geological and assay information, obtained from 32 m deep inclined holes are sampled and assayed every 1 m to generate wireframes from sectional interpretation, for grade control block modelling and ore outline generation. The ore outlines are then used by geologists and surveyors for final ore/waste discrimination and in-pit mark-up. In 2018, Houndé introduced blast movement simulation technology to better predict movement of ore resulting from blasting as a key measure in reducing ore loss and dilution. Production drilling and blasting is performed on contract by SFTP with Sandvik DP1500s drill rigs on 9 m benches with one-metre sub-drill using 115 mm diameter drill bits. Blasted material is excavated in 3 m high flitches except for Kari pump flat ore body where 2.5 m flitches are commonly used and 1.25 m flitches in some areas.

During 2021, AEL provided down-the-hole blasting services. The AEL plant on site consists of an ammonium nitrate mixing shed for the manufacturing of bulk explosives and four 30 tonne capacity iso tank containers for storage. The supply of detonators, boosters, bulk explosives, initiating systems and other explosives material into the site-based magazines for storage is the responsibility of AEL. A tender process for blasting services was carried out in 2021, with Maxam winning the tender and set to mobilize and begin taking on all of the associated services by mid-2022.

Waste rock dumps associated with mining operations are constructed to meet the stipulated guidelines of the Burkina Faso Mining and Explosive and Environmental Regulations. All areas earmarked for waste dumps are sterilized before dumping commences.

- subscription is required.

The “Houndé Process Plant” consists of a Carbon-in-Leach (“CIL”) plant with a nameplate capacity of 3.0Mt per annum (now operating at 4.0Mtpa) with Semi-Autogenous Ball Mill Crusher (“SABC”) milling circuit to produce an 80% passing 90-micron grind size. Ground fresh ore is fed to continuous centrifugal gravity concentrators to recover free and occluded gold in heavy particles (pyrite) to a low mass gravity concentrate. This gravity concentrate is processed through an intensive cyanide leach reactor followed by electrowinning to recover the gold. The CIL feed has the potential to be thickened and fed into a standard CIL circuit, with leach tails passing into a cyanide destruction process before being pumped to the Tailings Storage Facility (“TSF”).

Gravity
Feed for the gravity circuit is taken from the common mill discharge using a duty/standby pump arrangement. The gravity circuit feed stream is pumped to one of two single deck ‘vibrating ‘degritting’ screen to remove coarse (+2mm) material and fragments of broken mill balls and this oversize is returned to the ball mill feed. The screen undersize stream gravitates to one of two (duty/standby) 48” Knelson centrifugal concentrators and the tails slurry from the centrifugal concentrator gravitates to the mill discharge hopper. The concentrator is operated on a semibatch basis with periodic discharge of the coarse high SG material (gravity concentrate) to the concentrate storage hopper as part of the intensive leach reactor.

The intensive leach reactor (“ILR”) processes the concentrate once per day in a rotating drum leach vessel. Cyanide and caustic together with oxygen are introduced into the slurry and the drum is rotated for up to 20 hours to leach out gold and silver. At the end of this time the pregnant liquor is separated from the solids and pumped to the dedicated pregnant liquor tank. Reactor tails is pumped back to the mill discharge hopper for additional milling to recover any remaining entrained gold and silver.

A dedicated pregnant liquor pump feeds the gravity electrowinning cell in the goldroom with gold and silver recovered onto stainless steel cathodes and barren liquor returned to the pregnant liquor tank. The cathodes from the gravity electrowinning cell are treated separately to assist in metallurgical accounting and spent electrolyte is recycled to the head of the CIL circuit.

Leaching
Ore that is not recovered via the gravity circuit is screened to remove any extraneous trash (wood, plastic, etc.) then can either be sent to a thickener to increase thepercentage solids in the leach slurry, or pumped directly to a conventional carbon in leach circuit (“CIL”). The CIL circuit consists of a series of six agitated tanks where gold is dissolved in the presence of cyanide and oxygen as the slurry flows sequentially from Tank 1 to 6. The dissolved gold adsorbs on the coarse activated carbon particles which are pumped in a counter-current direction from Tank 6 to 1, becoming progressively more loaded with gold in the process;

Carbon Recovery
Once sufficiently loaded by the time the carbon reaches Tank 1, the carbon granules are pumped from the primary tank over a screen to remove the slurry. The clean carbon is then washed with hydrochloric acid to remove any acid soluble base metals and impurities, before being transferred to the elution circuit;

Elution and Gold Production
Concentrated cyanide solution is circulated in the elution column and heated to 120 degrees Celsius. After sufficient time to enable the gold to be released from the carbon, the gold bearing solution is sent for electrowinning and eventual gold bullion production; and

Tailing Detoxification and Disposal
The leached slurry, with minimal leachable gold remaining exits the CIL where the free and weak acid dissociable cyanide (“WAD”) are destroyed through a cyanide detoxification process using sulphur dioxide and oxygen with a copper catalyst to destroy the remaining cyanide complexes. The detoxified tailings are pumped to a plastic lined TSF, where the solid and liquid phases separate. The liquid phase is recycled back to the process plant and the solids allowed to dry and compact in the TSF.