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.

The Da Tambuk operation has been planned as an underground mining operation to produce 550 t/day of mill feed.

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 mine plan includes a portion of backfilled waste rock as cemented fill. Cemented fill is considered for areas where mining may take place adjacent to backfilled areas or where backfill plays a role in ground support. The cement is added to rock in the back of haul trucks, then hauled back underground. The cemented rock fill is then tipped into a dedicated muck back where a scooptram will mix the material and place it in the stope being backfilled.

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. The crushing facility will contain the main equipment listed below:
• stationary grizzly
• run-of-mine (ROM) dump bin
• jaw crusher vibrating feeder
• jaw crusher, 75 kW
• conveyor belts
• belt magnet and metal detector
• sizing screen
• cone crusher, 150 kW
• belt scale
• crushed material surge bin.

Haulage trucks will bring ROM material to the crushing plant. The material will be dumped directly from the trucks for crushing, although provision has been made for material to be dumped onto a temporary ROM stockpile if unscheduled crusher plant stoppages occur.

A stationary grizzly will be provided to prevent oversize rocks from entering the ROM dump pocket. With a nominal capacity of 18 m3, the dump pocket will be equipped with a vibrating feeder that will feed the ROM material to the jaw crusher. The jaw crusher will reduce the feed size from finer than 400 mm to less than 100 mm. Together with the vibrating feeder undersize material and the material from the secondary crusher discharge, the crushed material will be discharged onto a conveyor belt which will transport these materials to the sizing screen.

The sizing screen will be a vibrating screen with a final product size P80 of approximately 9.0 mm. The screen oversize will be conveyed to a cone crusher for additional crushing. The cone crusher will be in a closed circuit with the sizing screen. The screen undersize will be discharged onto a conveyor, which will transport the crushed material to a mill feed stockpile. The crushed material will then be loaded onto a ball feed surge bin with a live capacity of 200 t.

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. The grinding circuit will have the following main items of equipment:
• ball mill feed conveyor belt
• conveyor belt weigh scale
• ball mill, 3.2 m diameter by 3.7 m long
• mill discharge pumpbox
• cyclone feed slurry pumps
• classification cyclone cluster
• vibrating trash screen.

The material will be drawn from the mill feed bin at a controlled feed rate. A belt scale will be installed to control the feed rate to the ball mill. The mill new feed rate will be 25.5 dry t/h. The cyclone underflow will also constitute part of the feed to the mill. Process water will be added as required to maintain the slurry density in the ball mill at approximately 72% solids.

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 c ........