The Taparko gold mine is located along the eastern portion of the Proterozoic Birimian Bouroum-Yalogo Greenstone Belt. The belt has undergone regional lower greenschist metamorphism and is comprised of intermediate to mafic volcano-sedimentary successions with syn to post-kinematic granite and gabbro intrusions, which have been intruded by later dolerite and felsic-porphyry rocks.

Structural patterns in the area depict a large open Y-shape resulting from interference of NNW and NNE trending faults and shear zones. The most distinctive structural feature of this area is the NE trending Tiebele-Dori-Markoye fault system (and Bouroum NNW trending deformation corridor), which act as hosts to regional gold mineralisation. Primary and secondary structures associated the fault system result in mineralisation occupying both NE and NW trending features.

The Taparko deposits are situated on the eastern limb of the Y-shaped Bouroum-Yalogo greenstone belt, hosted by volcano-sedimentary rocks such as amphibolitic schists, mafic lavas, pyroclastics, and argillaceous sediments, all of which have been intruded by large bodies of diorite or quartz-diorite, and by diabase dykes.

The Bouroum and Yeou deposits are situated on the western limb of the Bouroum-Yalogo greenstone belt. The geology of the Bouroum and Yeou areas are characterised by clastic metasedimentary rocks intercalated with minor mafic tholeitic flows and sills and overlain by a thick series of subaqueous flows and tholeitic sills with intercalated, epiclastic and pyroclastic rocks. Metapelites, ferruginous quartzite and finally andesitic to dacitic volcanic rocks cap the older stratigraphy.

Gold mineralisation at the Taparko, Bouroum and Yeou deposits is predominately (sulphidepoor) quartz-vein hosted and controlled by shear-related veining and alteration.

At Taparko, gold mineralisation is developed in predominantly sediment-hosted structures, comprising anastomosing and shallow to steeply dipping shear zones, exhibiting multiple, superimposed, phases of veining, alteration and deformation. At Bouroum gabbro, basalts and tuffs (and notably their sheared contacts) represent typical host rocks, with metagabbro and granodiorite forming typical hosts at Yeou.

In general, across all deposits, the weathering profile is deep and typically results in extensive surface oxidation of bedrock to depths of up to approximately 100 m. In such areas, gold deposits typically comprise a surface oxide zone, an intermediate transition zone and a deeper fresh rock zone.

Taparko plant is a central point for the existing and future open pits. Current mining operations at Taparko are focused around multiple pits, namely: 35, 2N2K, Goengo, Tangarsi East (currently operating), Bouroum, Bissinga, Grand Trench (currently on hold) and Nayiri (new pit). The pits, however, are of relatively small sizes and all will be mined out before 2024. Currently, the main pits would include 35 and 2N2K which are both located in the nearest vicinity to the plant.

Production is undertaken through conventional drilling, blasting, loading, hauling, dumping and stockpiling processes.

3 Open Pit Geotechnical Considerations
The Taparko mining complex is formed from a number of small to medium size pits of varying maturity. The smaller pits generally mine oxide only, while the larger pits mine oxide and sulphide and are primarily excavated within fresh rock.

The Taparko and Bouroum mining complexes exhibit differing geological conditions. Bouroum is formed within gabbros, basalts (varying states of alteration) and tuffs, while Taparko is formed within meta-sediments, meta-volcanics and granodiorite.

Overburden slopes are formed from Saprolite that ranges in thickness but is in general approximately 25 m thick and can be considered soil strength with the presence of remnant structures that can lead to instability issues. The underlying fresh rock can be considered as Strong and with RMR values in the region of 55-65 with a very dominant foliation dipping at approximately 45° to the east.

35 Underground Mine Project
SRK has undertaken an underground mining study at the Taparko 35 pit to generate Ore Reserve Case and Base Case scenarios as defined by the Company. The purpose of the Taparko underground mining study was to determine if the LoM could be extended by mining below the 35 Pit and supplementing the feed from stockpiles to the plant after the completion of the Taparko open pits by the end of Q1 2021, as per the Business Plan 2021.

Portal location
The selected portal location is in the east (hanging) wall NE corner, below the pit access ramp. This location provides at least 20 m of wall above the decline to prevent the ramp being affected by the initial blasting. The ramp will act as a wide berm, which will reduce the amount of geotechnical work required to secure the wall above the portal.

Schedule
The mine schedule begins on 1 April 2022. SRK has been provided with the end of October 2020 surveys and final pit design. Lateral development tasks were scheduled with two jumbos at 240 m per month each.

The mine schedule was developed using a bottom-up sequence of sublevels spaced 15 m with a sill pillars in between the level 25 mRL and 40 mRL to allow high grades zones to be mined earlier in the schedule.

Crushing
The original Taparko crushing circuit consisted of a “soft ore” and a “hard ore” circuit. The soft ore crusher has been decommissioned, although the feed system from that circuit is still used (the “1-stage feed bin”). The hard ore circuit consist of a jaw crusher and two cone crushers. Primary crushed ore is screened using a double deck screen, with the oversize reporting to the secondary crusher and the middle fraction reporting to the tertiary crusher. Both screens discharge to a second double deck screen, which closes the tertiary crusher. The top deck of this screen is used to divert overload to a “pebble” stockpile. Additional ore is fed into the 1-stage feed bin from a 3-stage mobile crushing plant that was previously used for a heap leach operation. Pebbles, oversize from the secondary double deck screen and ball mill scats, are crushed and returned to the circuit via the pebble crusher.

Grinding
The original grinding circuit consisted of a second hand 5.0 m diameter, 7.1 m long ball mill, that was fitted with a 4,000 kW motor, operating in closed circuit with cyclones. For the 1.8 Mtpa upgrade, a “regrind” mill was added that treats cyclone underflow, with the primary mill converted to open circuit operation. Part of the cyclone underflow reports to a gravity circuit, which consist of a Knelson centrifugal concentrate, the concentrate from which is upgraded using a Gemeni shaking table. This circuit was part of the original installation, was decommissioned in the operation’s early years, but has recently been recommissioned. After screening for trash removal, cyclone overflow reports to the CIL circuit.

The Taparko process plant treats non-refractory oxidised saprolite and transitional and fresh saprock hosted gold ore through a conventional CIL circuit, producing doré on site. The plant commenced production in 2007 at a design production rate of 1 Mtpa. Subsequent upgrades and expansions took the plant capacity to 1.5 Mtpa in 2010, and to the current 1.8 Mtpa in 2012.

Cyanidation
The original cyanidation circuit consisted of six 830 m3 mechanically agitated tanks, giving a circuit residence time of 24 hours. Two additional tanks were added for the 1.5 Mtpa expansion, giving a CIL residence time of approximately 18 hours at 1.8 Mtpa. Carbon is added to all but the first tank, the tanks are fitted with Kemix interstage screens, and carbon is transferred using recessed impeller pumps. A ten tonne per day PSA oxygen plant was installed to improve leach kinetics; oxygen is injected into the CIL circuit though lances at the bottom and the agitator shafts. An Aachen oxygen r ........