The Akyem deposit is localized in the hanging wall (upper side or plate) of a regional fault that trends to the northeast (N70°E) parallel to regional structures and dips to the southeast (S60°E) parallel to the foliation developed in a Birimian host rock. The planar fault structure (thrust fault)[11,12] is intensely sheared and exhibits a mylonitic to cataclastic fragmental texture consisting of lens of metavolcanic fragments in a matrix of sheared and plastically deformed graphitic material. The presence of graphitic rubble zones suggests reactivation of the fault zone over time. The fault occurs in fine grained, gray green massive to locally sheared Birimian mafic metavolcanic rocks exhibiting chlorite and carbonate alteration that locally contain euhedral magnetite. Immediately overlying the metavolcanics is a distinctive gray green pink unit containing blue quartz phenocrysts in a mylonitic matrix (quartz epiclastic rock). The upper and lower contacts of this unit are typically sheared and brecciated, and the upper contact of this unit is locally in sharp contact with overlying light gray tan chert. This unit is considered sedimentary and represents a distinctive marker between the metavolcanic and metasedimentary units of the Birimian. The overlying metasedimentary rocks are for the most part turbidite sequences consisting of graywacke, argillites, black carbonaceous siltstone, and fine grained arkosic sandstones. This unit grades upward into a saprolitically weathered zone (deeply weathered bedrock largely altered to clay) that ranges from 10 to 50 m thick. The saprolite consists of lateritic clay and quartz fragments with as much as 25% weathered rock remaining within the saprolite. Near the surface, in the upper 1–5 m, red lateritic clay is developed as subsoil.

The Akyem mine is an orogenic gold deposit that has oxide and primary mineralization. The gold is found in shear zones within greenschist-facies metasediments that have kilometer-scale vertical and lateral extent. Gold occurs primarily in pyrite and secondarily as native gold in quartz veins.

The mining method at the Akyem mine involves removal of ore and waste rock from an open pit mine. The open pit is an elongated structure consisting of a large western lobe (Main Pit) and a small eastern lobe (East Pit), connected near the surface. The planned pit covers an area of approximately 345 acres (139 hectares).

Mining is conducted using large scale conventional hard rock drill and blast open pit methodology. Run of Mine (ROM) ore is trucked from the pits using CAT 785 DT’s.

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The ore sources that are being treated in the Akyem mill includes an Oxide ore (consisting of Oxide Mafic and Oxide Greywacke ores), followed by a deeper Primary ore body (consisting of primary Mafic and primary Greywacke ores).

The Akyem gold processing plant was commissioned in 2013 to treat an average of 8.5 million tonnes of ore annually. With the depletion of oxide ore.

The process plant consists of a large conventional SAG and Ball Mill in closed circuit configuration with an annual production rate of >8mt. The rest of the Process Plant consists of a carbon-in-leach circuit with cyanidation followed by elution and refining for gold doré recovery.

Tailings remaining after completion of the processing and precious metals recovery are conveyed by pipeline to a counter-current decantation (CCD) plant where the tailings are rinsed with decant return water to reduce WAD cyanide concentrations to less than 50ppm WAD cyanide prior to final disposal. After the CCD circuit, the tailings are transferred via a lined tailings trench, to an engineered, lined tailings storage facility (TSF) for permanent disposal.

Sparging is a closed circuit mixing process that passes pH-adjusted water from a mixing tank through the isotainer in a continuous circuit until the required concentration of liquid cyanide is achieved. On completion of the sparging process, the liquid cyanide is transferred from the mixing tank to a dedicated storage tank, ready for delivery by pipeline to the process plant. All pipelines used for the transfer of cyanide to the process plant or within the process plant are either double-piped or installed above containment facilities to prevent the escape of leaks or spills to the surrounding surface.

The cyanide mixing facility at Akyem is specifically designed to handle the bulk sparging operations.