The Natougou deposit can be described as a West African shear zone hosted greenstone gold deposit. Gold mineralization is associated with biotite and silica-sericite alteration, along with disseminated sulphides such as pyrrhotite, pyrite and minor arsenopyrite and chalcopyrite with occasional free gold. The mineralization is structurally controlled and is hosted primarily within a large shear zone and its associated alteration.

The main mineralized lode is interpreted as a flat-lying anticlinal shear that outcrops in the southeast and plunges gently to the northwest.

The mineralization has a strike length of approximately 2 km, striking towards a bearing of 315° and an across-strike length of approximately 1 km (towards 045°). The mineralization is gently folded with the fold axis oriented along strike and the limbs dipping gently at approximately 15°.

Mineralization is open across strike to the southwest as well as towards 315°, although the shear zone is relatively deep in these directions. The average true thickness of the mineralization is approximately 4 m. Drilling to the west of the resource area up to the felsic intrusive suggests that the shear zone does not continue within the intrusive. The interpretation of the shear zone was therefore stopped at the intrusive/volcanic contact.

Other minor footwall zones have been identified below the main shear zone. Although the footwall zones appear much less continuous and thinner than the main shear zone, some do contain significant gold mineralization. At the end of the 2015 delineation drilling program a short hole-extension program was completed to test the continuity of the footwall zone that was originally encountered in the central portions of the deposit by hole TPA0556, in which a secondary sheared and altered zone returned 10.23 g/t Au over 2.69 m downhole. Nineteen holes were extended to reach the footwall zone, for a combined total of 371 m. Based on interpretation of the results, 13 additional holes (including the original discovery hole) intersected the footwall zone. The combined results suggests that the footwall zone is on average 1.5 m thick with local high grade results returned of up to 31.98 g/t Au over 2.5 m downhole. The footwall zone is interpreted to be sub-parallel to and approximately 20 m below the main Boungou Shear. To date, the footwall zone has been traced over an area of approximately 300 m along strike by 90 m across strike, and remains open in all directions. The interpretation of this footwall zone was included in the current resource model. Other zones of gold mineralization are believed to exist below the main shear and will be explored by SEMAFO further in 2016.

Two types of alteration are significant with respect to the mineralised shear at Natougou. The two alteration types are locally termed the Boungou pink (BPK) and the Boungou bleached zone (BBZ).

The BPK type is a pink-brown alteration consisting of fine-grained biotite-plagioclase and is generally present over the entire width of the mineralised shear zone. It is the schistosity developed by the alignment of the biotite that gives the mineralised zone the sheared texture.

The BBZ type is a silica-sericite alteration generally developed as a discrete zone over widths of about 1 m within the BPK alteration. Variable amounts of quartz veining, often highly deformed (boudinaged or folded), can be observed within some of the BBZ. Small bands of silica-sericite are also interspersed within the wider zones of BPK alteration.

Mining uses a conventional open-pit mining method, with hydraulic excavators in backhoe configuration to mine both the mineralized zone and waste. The majority of the rock requires blasting and only the softer material located within the top 5m to 10m of the deposit is free digging and loaded directly by hydraulic excavators. Following the security incident in November 2019, the mining contractor, African Mining Services, decided to terminate the contract at Boungou. SFTP Mining was appointed as mining contractor in August 2020 and started mining works at Boungou on October 15, 2020. Production was maintained through this period with feeding of ore stockpiles to the ROM crusher through a local contractor.

Rock mass characterisation indicated a very thin Saprolite/Saprock domain (7m to 15m thick) underlain by very strong and competent metabasalts and metavolcanic sediments fresh rock mass domain. Structural fabric (joint and bedding) control pit wall stability.

Open pit mine production at Boungou averages approximately 3,600 t/d of ore in bedrock, from the West, East and West Flank pits, that can be blended with ore currently on the Rompad up to 4,000 t/d for processing in the mill. The first phase of the West pit was completely mined out in 2020.

The production, drilling and blasting operations are carried out on 6m benches on ore and 9m bench on waste. To be able to achieve the best degree of selectivity, ore mining is undertaken on a 2m flitch. The highly weathered (strongly and moderately oxide) zone are amenable to free digging or soft blasting. Emulsion is used in both wet and dry blasting conditions for efficiency.

A static grizzly (800 mm), mounted above the ROM bin, will prevent the ingress of oversize material. A rock breaker will be installed to assist in breaking down oversize material, retained on the static grizzly. Ore will be withdrawn from the ROM bin, by a variable speed apron feeder, directly to a vibrating grizzly (75 mm aperture size). Oversize from the grizzly will report directly to the jaw crusher, which will operate in open circuit. Crushed ore from the crusher discharges, together with undersize from the grizzly, directly onto the primary crusher discharge conveyor, which will convey the crusher product to the mill feed bin.

The crushed ore product conveyor will be fitted with a weightometer, to monitor the crushing area throughput and for controlling the apron feeder variable speed drive.

The crushing circuit will be serviced by a single dust collection system, comprised of a series of extraction hoods, ducting and a bag house. Dust collected from this system will be discharged onto the crusher product conveyor.

Crushed ore will be withdrawn from the mill feed bin, by a variable speed apron feeder. The feeder will discharge onto the SAG mill feed conveyor, which will convey the crushed ore to the SAG mill feed chute. The SAG mill feed conveyor will be fitted with a weightometer, used for controlling the speed of the apron feeder and for mass accounting of feed presented to the grinding circuit.

Hydrated lime will be added directly to the SAG mill feed conveyor, via the lime variable speed rotary feeder. The hydrated lime storage silo will have a storage capacity of 60 t, equivalent to 47 days storage at 1.34 Mtpa.

The grinding circuit will be a SATMC circuit, comprised of a single, variable speed, SAG mill and a single fixed speed tower mill. The SAG mill will operate in closed circuit with a pebble crusher, whilst the tower mill will operate in closed circuit with hydrocyclones. The product particle size exiting the grinding circuit (hydrocyclone overflow) will contain 80% passing 63µm material.

To meet the design throughput, and achieve the required leach product size, a 6.10m diameter x 3.72m EGL SAG mill (20ft x 12.2ft; 2.30 MW) and a 3.3 MW tower mill will be required.

Crushed ore, reclaimed from the mill feed bin, will be conveyed to the SAG mill feed chute via the SAG mill feed conveyor. Process water will be added to the SAG mill feed chute, to control the in mill pulp density. The SAG mill will be fitted with discharge grates which will allow slurry to pass through the mill and will also relieve the mill of pebble build-up. The SAG mill product will discharge to a single deck vibrating screen, for size classification.

SAG mill discharge screen oversize will be conveyed to a pebble crushing circuit. Undersize from the discharge screen will gravitate to the SAG mill discharge hopper, where it will combine with discharge from the tower mill, prior to being pumped to the classification hydrocyclone cluster by one of two (duty/standby) variable speed hydrocyclone feed pumps. The classification hydrocyclone cluster overflow will gravitate, via a trash screen, to the pre-leach thickener feed distribution box. The trash screen undersize will constitute the pre-leach thickener feed whilst trash screen oversize will be discharged to a trash bunker.

Oversize from the SAG mill discharge screen will be conveyed to the pebble crusher feed bin, via two belt conveyors. A self cleaning tramp metal magnet will be mounted above the pebble recycle conveyor, to remove any scrap metal and steel media which could potentially damage the pebble crushers.

The Natougou mineralization is predominantly hosted in quartz veins and a significant quantity of the gold occurs as visible, free gold. Sulphide minerals comprise pyrrhotite, arsenopyrite pyrite, and minor chalcopyrite. The Natougou quartz vein deposit is considered free milling. A significant component of the gold is amenable to gravity recovery and consequently the proposed process facility will consist of the following process areas:
• Primary crushing and coarse ore storage.
• Grinding, utilizing a SAG Mill, Tower Mill and Pebble Crusher (SATMC) circuit.
• Leach and CIP Carousel circuit.
• Gold recovery and carbon handling circuit (consisting of a cold acid wash followed by a split, Anglo American (AARL) elution circuit and horizontal carbon regeneration kiln).
• High density tailings handling and disposal.

The Natougou project process plant will be designed to process 4,000 tpd (1.34 Mtpa) with an average gold head grade of 4.15 g/t.