The Project comprises the Tuzon deposit (Tuzon), the Dugbe F deposit (Dugbe F) and several gold ‘prospects’ including the central Bukon Jedeh.

The Project is located close to the suspected boundary between the Archaean-aged Liberian Province and the Paleoproterozoic Eburnean Metamorphic Terrane (2.2-2.0 Ga), which is generally considered to be contemporaneous with the Birimian rocks (2.2-1.9 Ga) in the rest of West Africa.

The Dugbe Shear Zone (DSZ) is a major WSW-ENE orientated shear zone that crosses the area and is thought to have been an important control on gold mineralisation in the area. The Tuzon and Dugbe F deposits occur 0.5km and 2km to the north of the DSZ, respectively.

The gold mineralisation at Tuzon and Dugbe F is hosted by granulite-facies, orthopyroxene gneiss and predominantly localised within a single layer, sub-parallel to the contact with adjacent feldspar-biotite gneiss or orthopyroxene-garnet gneiss. The deposits are cross-cut by at least two distinct phases of pegmatitic dyke. The gold mineralisation is typically hosted by orthopyroxene-gneiss and is spatially associated with elevated levels of sulphide; principally pyrrhotite and arsenopyrite. The gold mineralogy consists of four main types; electrum (Au, Ag), gold amalgam (Au, Ag, Hg), native gold and maldonite (Au2Bi).

The Dugbe F deposit has a surface footprint of approximately 3,400m by 1,500m, with a dominant strike direction of 020°. The mineralisation outcrops over most of this strike length, along the western parts of the deposit. The mineralised zone comprises a generally gently south-east dipping (5°- 20°) tabular unit characterised by occasional “rolls” or undulations. The mineralised zone ranges in thickness from less than 1m to 25m, averaging 6m. It thickens and thins, both along strike and down dip, but displays good geological continuity overall.

The overall form of the Tuzon deposit is that of a SW plunging refolded recumbent fold, with closure at the north-east end. The average plunge over the length of the deposit is approximately 12°. It has a length of approximately 1,800m and an average strike of 030°. The mineralised footprint is typically over 150m and up to 375m wide. The deposit outcrops at surface over much of the strike length. The deepest part of the current deposit model is 350m below surface. The refolded contact closes at the north-east end of the deposit where the mineralisation outcrops. The western fold limb is approximately 1,800m in length and between 10m and 30m thick and the eastern fold limb is 1,000m in length and between 30m and 120m thick. Four other smaller lenses also occur in the central and southern part of the deposit parallel to the western limb of the deposit as selvages of orthopyroxene gneiss within the feldspar-biotite gneiss. Within the major fold limbs, the mineralisation is divided into high grade (>0.8 g/t Au) zones within a surrounding low grade (0.3-0.8 g/t Au) domain.

The oxidation profile at both deposits has an average thickness of less than 5m and there is no documented transitional/saprolitic zone.

These deposit types are different from others in the region. They may be broadly classified as a highly metamorphosed ‘orogenic type’ gold deposit although it is atypical in some respects, particularly the high metamorphic grade of the host rocks and lack of visible structure-related control on this mineralisation, and the apparent absence of well-developed alteration assemblages. The deposits are relatively stratiform, largely hosted by a single lithology.

The deposits may more appropriately be compared to granulite facies gold deposits, which are known from cratonic regions in Canada, Australia and China. Notably, both Tuzon and Dugbe F display evidence of gold predating peak metamorphic conditions and therefore differ from most typical Birimian deposits where mineralisation is largely associated with late transcurrent shearing. In the absence of direct evidence in support of an Archaean origin, a Birimian age is proposed for these deposits.

At the Sackor Prospect, the gold mineralisation is also hosted by sulphide-bearing orthopyroxene gneiss interpreted as an overturned fold with closure to the south-east. In the absence of drilling, the geology of the other prospects is less well understood.

Both the Tuzon and Dugbe F deposits are shallow and so amenable to open pit mining operations. The planned open pits will be mined utilising conventional truck and shovel method to supply mill feed to the run of mine (RoM) tip (near Tuzon) and waste to the respective pits waste stockpile facilities.

A feasibility level geotechnical study was completed for Tuzon (Coffey, 2014), but no work was carried out on the Dugbe F deposit. Given the similarity of the deposits, the geotechnical characterisation of Tuzon was extrapolated to Dugbe F. The configuration of the Dugbe F pit means only the south-eastern high wall will be at the maximum allowable angle, which reduces the risk of this extrapolation.

Typically, the weathered material (0m to 15m deep) is classified as ‘poor rock’ and the fresh material is classified as ‘good to very good rock’. There is little transitional material.

In Tuzon the structures in the footwall are predominantly dipping to the south-west, and in the hangingwall, structures are dipping to the south-east. Geotechnical domains were determined for Tuzon and used in further modelling. Stability modelling resulted in overall slope angles between 45° and 56° targeting factors of safety of 1.3 and 1.5. These slopes were modelled taking into consideration the groundwater conditions.

The area is a low seismic risk area and groundwater is expected to have a moderate influence on the planned slope angles.

Based on the preliminary optimisation work a processing capacity of 5Mtpa was selected.

The planned Dugbe F pit is approximately 2.5km by 1km (100ha) and the planned Tuzon pit is approximately 1.5km by 0.78km (75ha). Each pit will have an adjacent single large waste storage facility (WSF), eventually containing 300Mt of waste rock over an area of 280ha.

A basic production schedule was developed in Whittle. Both pits were scheduled at the same time to find the best combination of production across both pits to meet the 5Mtpa processing target. Waste was deferred in the early years of production to defer mining capital and operating costs.

No stockpiling nor high-grading options were considered. These options, and a further optimised production schedule, will be developed during further study work.

The schedule results include:
• 66Mt of potential mill supply, with an estimated grade of 1.34g/t. Of this total, 48Mt are expected from Tuzon and 18Mt from Dugbe F;
• 299Mt of waste, for an overall strip ratio of 4.5 (t:t);
• 3% of the scheduled material is oxide, while the remainder is fresh material;
• An average annual mining grade range from 1.15g/t to 1.57g/t of gold over the life of mine (LoM);
• 75% of the potential mill feed is classified as Indicated material.

Mining will be undertaken by conventional open pit drilling and blasting, and load and haul. 12m benches are planned that will be mined in smaller flitches when in mineralised material. Only 3% of the orebody is weathered material that is free dig. There is almost no transitional material. Current work supports an owner mining operation with leased equipment but the option to contract out the mining will be investigated in more detail in the FS.

In order to selectively mine and retain operational flexibility across two pits, smaller 110t excavators were selected to meet the 5Mtpa mill feed and 40Mtpa total material movement targets.

A fleet of 35 tonne track-mounted drills are planned, with minimum 14m mast for blast hole drilling 170-200mm blast holes from 3m to 13.2m in a single pass without requiring rods to be changed.

Free dig and blasted waste will be loaded into and hauled by 90 tonne ridged haul trucks, and dumped in designated waste storage facilities.

Free dig and blasted mill feed will be loaded and hauled with the same equipment to the RoM pad, to either be direct tipped into the crusher or placed in a temporary stockpile.

Crushing
The primary crushing circuit will consist of two parallel jaw crushers operated in open circuit to produce a crusher product size P80 of 130mm. Primary crusher product will be conveyed to a crushed ore stockpile. The design will include a water dust suppression system.

A trade-off will be conducted during the next Project phase to confirm the primary crusher circuit selection as either two off parallel jaw crushers or a single gyratory crusher.

Milling and Classification
The milling circuit is configured as a semi-autogenous ball mill crusher (SABC) circuit comprising a primary SAG mill and pebble crusher and secondary ball mill circuit.

Ore will be withdrawn from the crushed ore stockpile by variable speed feeders feeding onto the SAG mill feed conveyor. A weightometer will be used to control the SAG mill feedrate. The SAG mill discharge will be screened via a trommel screen and oversize will be conveyed to the pebble crusher circuit prior to being recycled back to the SAG mill feed. The circuit will also include a SAG mill pebble bunker to facilitate mill load control and it is envisaged that the SAG mill will be operated using an advanced mill control system.

The SAG mill will operate in reverse open circuit, where the SAG mill discharge slurry is fed to the ball mill discharge sump and the combined stream is pumped to a cyclone classification circuit. Cyclone underflow will report to the ball mill feed for further grinding. Mill circuit cyclone overflow at a target grind of 80% passing 75µm will gravitate to a pre-leach thickener.

Lime will be added to the SAG mill feed via a silo and variable speed feeder. Provision has been made for a ball loading system for both mills.

The circuit does not currently include provision for gravity recovery as this was not included in the optimised flowsheet used in the historical testwork programmes. The opportunity for inclusion of a gravity recovery circuit will also be asssed in the 2021 ALS testwork programme.

The Dugbe Gold Mine Project 5.0 Mtpa gold processing plant design has been based on a typical SAG and ball milling circuit followed by a CIL gold recovery circuit.

Pre-Leach Thickening
The mill circuit classification cyclone overflow stream will gravitate to the pre-leach thickener via a vibrating trash removal screen. The trash screen oversize reports directly to a trash bin, whilst the underflow reports to the pre-leach thickener via a sampling system.

The pre-leach thickener will produce an underflow product of 45% solids (w/w) as feed to the CIL circuit. Flocculant solution will be added to the thickener to assist with settling of particles. The thickener overflow product gravitates to the process water circuit.

Carbon in Leach (CIL)
The CIL circuit comprises a series of mechanically agitated, leach and carbon absorption stages to achieve a residence time of 24 hours.

Each tank will be fitted with a vertical, mechanically swep ........