Overview

Deposit type

• Vein / narrow vein
• Mesothermal

Summary:

At Agbaou, the target deposit type being explored for is the mesothermal auriferous sulphide (pyrite + pyrrhotite) and quartz vein style mineralization. The gold mineralization within Agbaou deposit is hosted within a specific quartz vein type that occurs along a broad area and can be characterized by a wide range of quartz-vein types, brecciation, boudinage, sericitic and carbonate alteration.

The lateritic cover is generally between five and ten metres thick with a very well developed weathering profile is over much of the area.

Mineralization at Agbaou can be broadly separated into two categories: laterite cap (generally >0.5g/t Au) and primary (free gold and sulphide hosted). The laterite cap, which covers the entire deposit area, is of variable thickness (1 to 5m) and represents secondary (re-mobilized) mineralization. The primary mineralization is associated with a system of gold bearing quartz-veins hosted by tightly folded Birimian-age sedimentary and volcanic rocks. The quartz veins can occur within either meta-volcanic or meta-sedimentary rocks, but the host rock is typically strongly sheared. The primary mineralized envelope is broad (60 to 100m), consisting of a number (up to seven zones in Agbaou Main) of mineralized zones that generally follow the limb of the regional fold. Particulate gold mineralization is located within quartz veins and along wall rock-quartz vein boundaries.

The mineralized quartz veins at Agbaou have a visually distinctive texture that has been described as “mottled”. Gold mineralization is also associated with variable amounts of sulphides, mainly pyrrhotite and pyrite. These veins are easily identifiable in the diamond drilling core intersections from the fresh rock below the saprolite/fresh rock boundary.

The deposits are aligned along a northeast trending, steeply southeast dipping structure that marks the axial plane of the large-scale, regional fold.

Mining Methods

• Truck & Shovel / Loader

Summary:

The designed pits are split into three main areas; North, West and South Agbaou pits across predominantly oxide and fresh ore zones. Oxide ore requires very limited drilling and blasting, and transition ore is limited due to the approximately 10 m wide zone in which it occurs.

Drill and blast in the transition and fresh zones is carried out by the mining contractor using production blasthole drilling with explosives, accessories, loading and initiation provided by EPC Groupe.

The Agbaou pits are mined using contractor Komatsu PC2000 (210 t), Caterpillar 6015 (150 t) excavators, and Caterpillar 777 (90 t) haul trucks. The mining operating methodology is open cut mining on 10 m benches and flitched off at 2.5 m increments including the heave from blasting. Waste is taken to the designated waste dumps adjacent to each of the pit stages. Later in the mine life waste stripping will use 3.3 m flitches to maximize extraction of the waste.

The production schedule is balanced to mine approximately 25 Mt/a of rock in 2023-25, including the 20 Mt completed in 2023, with mining currently forecast to be complete in 2026. It is noted that the processing schedule includes mineralized waste (1.3 Mt, 0.46 g/t, 19 koz) to sustain the operation during 2024 and 2025. Exploration is ongoing at the time of reporting to replace the mineralized waste and increase profitable production.

Comminution

Crushers and Mills

Summary:

The open circuit primary crusher and open circuit secondary crusher deliver a product which is nominally P80 of 30 mm to the crushed ore surge bin and stockpile ahead of the SAG mill.

The milling plant consists of a primary Outotec SAG Mill, 5.1 m diameter by 5.5 m long with 2.3 MW installed power, operated at 72% critical speed, with a discharge screen and the pebble crushing circuit receiving >12 mm and <30 mm pebbles. The secondary Outotec Ball Mill is 4.5 m diameter by 6.9 m long with 2.3 MW installed power operated at 75% critical speed. The secondary mill is in closed circuit with a hydrocyclone cluster with eleven 380 mm cyclones. The milled product has a nominal P80 of 75 µm.

Processing

• Crush & Screen plant
• Gravity separation
• Smelting
• Centrifugal concentrator
• Carbon re-activation kiln
• Concentrate leach
• Inline Leach Reactor (ILR)
• Agitated tank (VAT) leaching
• Carbon in leach (CIL)
• AARL elution
• Carbon adsorption-desorption-recovery (ADR)
• Solvent Extraction & Electrowinning
• Cyanide (reagent)

Summary:

The process for the recovery of gold at Agbaou is a conventional free-milling CIL circuit consisting of crushing, two stage grinding, gravity recovery, cyanidation, followed by electrowinning and smelting to produce gold doré. Plant tailings are disposed to an engineered TSF located a few hundred metres from the process plant after cyanide destruction.

The basic plant flowsheet includes the following main areas:
• Primary and secondary crushing;
• Crushed ore storage and reclaim;
• SAG mill – open circuit with pebble crushing;
• Ball mill – closed circuit with cyclone classification;
• Gravity concentration;
• Intensive cyanide leaching of concentrate;
• CIL leaching;
• Elution circuit, electrowinning and gold smelting;
• Tailings pumping to disposal site;
• Including cyanide destruction;
• Reagent mixing, storage and distribution;
• Process, raw and potable water distribution;
• Air supply services including oxygen plants.

The gravity circuit treats a portion of the hydrocyclone underflow, after degritting at 2.5 mm, through a Knelson XD30 concentrator with the concentrate being leached in a Gekko Systems inline-leach-reactor (ILR) with a dedicated electrowinning cell. Historical gravity recovery is reported at approximately 30%, although some production reports indicate a range from 20% to 44%.

The coarse grit and the ILR tails are returned to the milling circuit for additional size reduction prior to the leach train.

Leaching follows trash removal at 0.7 mm x 18.0 mm through a vibrating screen. There are six 2,000 m3 CIL tanks resulting in a total leach time of 15 hours for saprolite ore and 29 hours for fresh ore due to higher density. The CIL tanks have Alloytech 0.833 mm wedge wire interstage screens. Carbon is pumped counter current with recessed impellor pumps, prior to transfer to the elution circuit. Final tailings safety screening is completed with a vibrating screen at 1.0 mm aperture.

The split AARL elution circuit consists of one rubber lined acid wash column and a separate stainless steel elution column with a capacity of 6.5 tonnes of carbon. Regeneration of carbon is completed in an electrically heated 350 kg/h rotary kiln. The regeneration kiln is located within the elution section with quenched carbon pumped to the last CIL tank with fine carbon removal by screening.

The gold room contains the ILR with two electrowinning cells (one for gravity and one for elution), each being 1.0 m x 1.0 m with 18 steel wool cathodes (expandable to 22 cathodes). Gold slimes are smelted on site into doré for final shipment to the refinery.

Cyanide detoxification is achieved in two tanks, offering a total residence time of two hours with the weak acid dissociable (WAD) cyanide content monitored continuously by analyser. Detoxified tailings are pumped to the unlined downstream constructed TSF for spigotting to encourage beaching. Recovered water is pumped back to the plant for reuse.

Water Supply

Summary:

Water supply is 71% from recycled process water and 29% from the water storage dam and/or from boreholes.

The water storage dam (WSD) comprises a valley storage upstream of the TSF and adjacent to it. The storage is approximately 1.035 Mm3 and some 1,300 m from northeast to southwest at full capacity. The WSD has a catchment area of 381 ha and when the pond volume is at maximum level, the reservoir surface area is 49 ha. It has a floating pontoon equipped with an intake pump adjacent to the WSD embankment. The basin area has a permanent spillway on the southeast side. The WSD embankment is common with the TSF east embankment and comprises engineered fill with a bulk fill zone on the downstream face.

Filtered and potable water is supplied after treatment of raw water and stored prior to distribution for process or domestic use. A dedicated 50 kL potable water tank is located at the processing facility and a 10 kL potable water tank at the mine service area (MSA).

Water consumption
Sufficient water has been maintained since 2015 with pit dewatering bore water being used to supplement the water supply as required. During 2020 to 2022, water sourced from the raw water dam and bores averaged 1.6 Mm3 per annum or 0.47 m3 per tonne ore milled.

Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Chief Geologist	Bindè Martin ADI		Sep 3, 2024
General Manager	Herman Prinsloo		Sep 3, 2024
Mine Technical Services Manager	Michée Gnagnon		Sep 3, 2024
Operations Manager	Jurie Majoor		Sep 3, 2024
Plant Maintenance Superintendent	Jean Jacques Kouadio		Sep 3, 2024
Process Manager	Mohamed Traore		Sep 3, 2024
Supply Chain Superintendent	Mireille Tanoh-N’Dri		Sep 3, 2024