The geology near the Da Tambuk deposit comprises a northeast trending assemblage, from west to east, that includes a thick sequence of black and grey shales (locally with rare graphitic beds), mafic tuff and bedded chert, chlorite sericite schist and variable chlorite sericite schist. Locally, the assemblage is intruded by feldspar phyric quartz eye porphyry, and leuco grabbroic units. In the area of mineralization, strong silicification is noted locally, along with quartz veining.

A zone of phyllic alteration (sil-ser-py) has been mapped over 700 m of north-south trending strike between the Mato Bula north and Da Tambuk south. This zone of alteration may prove to be the linking structure between the Mato Bula north and Da Tambuk prospect, and if true, presents 700 m of prospective strike.

This trend passes 200 m to the east of Mato Bula North, which is a gold-rich volcanichosted massive sulphide (VHMS)-type target found on the southern licence boundary of the Adi Dairo concession. The alteration indicates that Da Tambuk prospect appears to be on a separate trend with Mato Bula and Silica Hill. This hypothesis is supported by the different geochemical nature of Mato Bula North (high copper, low gold) verses Mato Bula, Silica Hill and Da Tambuk (high gold, low copper). In addition, Mato Bula and Silica Hill are hosted within altered schist, whereas Mato Bula North is hosted higher up in the sequence in the VTSM unit. However, this theory cannot be confirmed without further detail mapping to the south.

Foliation in the area is trending south- southwest (190°), dipping steeply (60 to 80°) towards west-northwest, locally swinging up to 30° to trend 218°, dipping (80 to 85°) towards northwest.

Exploration efforts on the Adyabo Property currently target two deposit types: gold-rich VHMS and orogenic lode-gold mineralization. A spatial relationship between these deposit types is noted on the property and may be related to reactivation of hydrothermal pathways or redistribution of deposited mineralization during orogenesis.

The Da Tambuk deposit, located 4 km northeast along strike from Mato Bula, was originally targeted due to its intense alteration signature determined from Landsat image interpretation. Systematic exploration, including reconnaissance regional soil sampling, delineated a 1.2 km long gold-in-soil anomaly with concentrations greater than 100 ppb gold. Local associations of lead and molybdenum soil anomalies were also present. The highest gold concentration recorded in soils was 5 ppm gold, and no previous artisanal workings were identified in this area. Several trenches were excavated, and one trench intersected 16 m grading at 3.95 g/t gold, including 4 m at 14.53 g/t gold.

Upon initiation of trenching, artisanal activities commenced. Staged trenching and subsequent drilling determined that mineralization is associated with moderate to intense silica alteration and quartz veining, and disseminated to semi-massive pyrite, minor chalcopyrite, and sphalerite. The host rock is a pyrite-rich (greater than 10%) sericite schist that attains a thickness of 50 m.

A combination of cut-and-fill mining and sublevel stoping was considered for the underground operations. Cut-and-fill will be used to mine areas with irregular mining shapes that would be unsuitable for sublevel stoping, which is a bulk mining method.

Cut-and-fill requires placing waste rock or tailings into mined out excavations for use of both as ground support and as a working platform for subsequent mining cuts.

Sublevel stoping does not necessarily require backfill. The method involves blasting large voids underground that become non-entry stopes. The method requires using remote control mucking equipment, which is standard practice in modern underground mining.

CUT-AND-FILL MINING
The proposed cut-and-fill mining involves the following steps:

1. An attack ramp is driven off the main access ramp at a grade of -15% into the mineralization.

2. The first cut is excavated by driving along the vein to the width of the vein. This may be done in stages to allow partial backfilling of mined-out areas.

3. If the mineralization is narrow, blast holes will be drilled upwards into the next cut and “slashing” the rock down into the first cut. If the mineralization is wide or if rock stability is not adequate for large spans, then the first cut will be backfilled immediately after mining. For both options, this step involves backfilling the mined-out void with rock, tailings, cemented rock, or cemented tailings.

4. The attack ramp is slashed to raise the access to the next cut elevation.

5. Steps 1 to 4 are repeated until the stope height is mined out. Depending on the situation, a sill or crown pillar is left between stopes as regional support and to support the backfill.

SUBLEVEL STOPING
Sublevel stoping generally involves establishing a system of stope access tunnels for drilling blastholes and for loading blasted ore. Blasthole drilling drifts are driven into the mineralization to allow access for longhole drilling equipment. Drawpoints are then developed at a lower level to enable mucking of blasted ore.

Sublevel stoping is undertaken in overhand and underhand configurations. Overhand configurations involve advancing lower panels of a stope to be mined out first, after which the upper panels are mined out, dropping the rock to drawpoints located at the lowest point of the stope.

With underhand configurations, the stope is mined out from the top to the bottom, with blasted rock being mucked from each level. Blastholes are drilled upwards from the sill drives, with rock mucked from the same drive used for drilling.

In the case of Da Tambuk, underhand sublevel stoping is considered appropriate, since this approach minimizes the length of time between developing stopes and production from stopes.

The underground operations will be accessed through a 3 m by 3 m spiral access ramp. The main ramp will commence at an elevation of 1,239.5 m and descend to an elevation of 1,091 mamsl. Stopes will be accessed through 30 m long crosscuts into the mineralization.

The mine has been designed with the following criteria:

• minimum (cut-off) gold grade included in mine plan of 2.2 g/t

• crown pillar of 10 m left against surface

• minimum mining width of 2 m

• main ramp tunnel dimensions 3 m high by 3 m wide

• cross cut tunnel dimensions 2.5 m high by 2.5 m wide

• maximum grade of ramps 15%

• maximum grade of crosscuts –15% (for attack ramps)

• vertical spacing of levels of 15 m

• ventilation shaft diameter of 3 m

• maximum height of cut-and-fill lift of 5 m

• maximum height of sublevel stoping panel of 15 m.

The Da Tambuk processing facilities are designed to process at a nominal rate of approximately 200,000 t/a, or 550 t/d, of gold- silver bearing material from an underground mining operation to produce gold-silver doré product.

The proposed process flowsheet is summarised as follows:

- Conventional crushing and ball mill grinding for comminution with a cyclone for particle size classification of the ground mill feed. A centrifugal gravity concentrator in the grinding circuit will be used to recover coarse and liberated gold particles, and a shaking table will be used to up-grade the gravity concentrate before smelting.

- The ball mill cyclone overflow will be treated in a six-stage CIL circuit to extract gold and silver from the feed material using sodium cyanide solution. The extracted gold and silver will be adsorbed from this solution onto activated carbon.

- The gold and silver loaded carbon will initially be acid-washed to remove calcium and other impurities, followed by the elution, or stripping, process to recover gold and silver from the carbon into a gold-and-silver-bearing pregnant solution. Then, the gold and silver will be recovered from the pregnant solution onto cathodes by electro-winning.

- The eluted carbon will be reactivated in a thermal kiln followed by attrition to remove carbon fines before being returned to the CIL circuit.

- The CIL tailings will be treated to destroy WAD cyanide by a sulphur dioxide/air procedure. After the chemical treatment, the WAD cyanide concentration is expected to reduce to the level that meets regulatory requirements.

- The detoxified tailings will be pumped to a thickener to recover the process water.

- Process water will be recycled from the tailings thickener overflow, and this will be supplemented with the water recovered from the tailings containment facility. Fresh water will be used for reagent preparation and gold-silver loaded carbon elution circuit as well as for water make-up purposes, as required.

The Da Tambuk processing facility will consist of the following unit operations:
• two-stage crushing and screening
• crushed fine material storage bin and reclaim system for grinding
• ball mill grinding and classification
• gravity recovery circuit
• CIL circuit
• carbon acid washing, elution and thermal reactivation
• electrowinning and smelting
• cyanide detoxification
• tailings thickening and delivery system.

CRUSHING CIRCUIT
The crushing circuit will reduce the mined material size from a nominal top size of 400 mm to a product size P80 of 9.0 mm in preparation for the grinding process.

GRINDING CIRCUIT
The grinding circuit will reduce the size of the crushed material to a final product size of P80 of 80 µm, suitable for the subsequent gold recovery by gravity concentration and cyanide leaching processes.

GRAVITY CONCENTRATION AND CONCENTRATE TABLING
The gravity concentration circuit with a centrifugal concentrator and a table is designed to recover coarse gold grains from the cyclone underflow. The concentrate from the centrifugal concentrator will be further upgraded on a shaking table for on-site smelting.

A nominal 30% portion of the cyclone underflow in the grinding circuit will be directed to the gravity circuit for recovering the liberated coarse gold grains. The gravity circuit feed will initially be screened to remove oversize and trash materials greater than 2 mm in size. The screen oversize material will be returned to the grinding circuit for further grinding.

CIL CIRCUIT AND GOLD RECOVERY CIRCUIT
The gold and silver will be leached from the ground material with a sodium cyanide solution, and the extracted gold and silver will be adsorbed onto granules of activated carbon (carbon) in a series of agitated leach tanks.

The cyclone overflow will be thickened in a high rate thickener to approximately 47% w/w solids. The thickener overflow will be reused as process water. The thickened slurry will feed into the No. 1 CIL tank and flow sequentially from Tank No. 1 to Tank No. 6. The carbon will be transferred counter-current to the slurry flow, from Tank No. 6 to Tank No. 1. The gold and silver dissolved will be simultaneously collected onto the carbon. The loaded carbon will be removed from Tank No. 1 CIL and transferred to the carbon elution circuit to recover the gold and silver. After elution, the carbon will be reactivated in a carbon kiln and returned to the leach tanks.

Loaded carbon will leave the first CIL tank and report to the loaded carbon screen equipped with spray water nozzles to wash the slurry off the carbon. The loaded carbon (screen oversize) will be transferred to the carbon elution circuit for acid wash treatment and subsequent gold/silver elution. The screen underflow will be returned to the first CIL tank.

ACID WASHING
Loaded carbon will enter the acid wash tank from the loaded carbon screen. Under normal operating conditions, the loaded carbon will first be rinsed with a diluted acid solution (washed), then neutralized with caustic solution, or thoroughly rinsed with water, and then forwarded to the subsequent elution stage.

LOADED CARBON ELUTION/DESORPTION/STRIPPING
The gold and silver adsorbed onto the carbon will be desorbed/eluted in the elution column.

After acid washing, the loaded carbon will be pumped to the elution column. The elution solution will be heated. After reaching the elution/stripping temperature, the solution will be pumped upward through the elution column. The elution column/strip vessel will be designed to treat an approximately 1.1 t batch of loaded carbon, although the planned production rate is approximately 0.6 to 1.1 t depending on mill feed grade and operational conditions. The elution/stripping of gold and silver from the loaded carbon will be accomplished using a modified Zadra based elution process.

ELECTROWINNING
The pregnant solution will enter the electrowinning cells from the pregnant solution stock tank. The gold and silver will be electro- plated onto stainless steel wool cathodes. The solution leaving the electrowinning cells will flow by gravity to the barren solution tank for making up to strength with caustic and cyanide for the following elution/stripping cycle. The cathodes will be lifted out of the cells, and the deposited metal will be washed off and collected in a sludge tank. The precious metal bearing sludge will then be pumped to the electrowinning sludge filter press to remove the bulk of the solution, which will be reused in the electrowinning circuit or recycled to the leach circuit. The dewatered metal sludge will be placed into trays for drying in the drying oven, followed by smelting.

The gold and silver will be smelted into doré bars. The metal sludge will be mixed with fluxes, typically a combination of borax, nitre, and silica sand. Smelting will take place in a tilting crucible furnace. A cascading mould system will be used to collect the melt metals. The doré bars will be cleaned to remove adhering slag and will be stored in the doré safe until the bars are despatched to their final destination.