Ad Duwayhi lies within the Afif composite terrain in the central Arabian Shield. The Afif terrain consists of a complex assemblage of volcanic arc sequences and a continental microplate that are overlain by successor-basin volcano-sedimentary sequences (Bani Ghayy and Murdama Groups). All these rocks were intruded by post-tectonic granitic rocks.

The deposit lies at the southern end of a zone of Pre-Cambrian volcano-sedimentary rock, which have been overprinted by greenschist facies metamorphism. The deposit is located to the north of a fault bounded belt of folded meta- sediments and plutonic rocks. A granodiorite body lies to the east of the deposit, with the deposit stratigraphy cut by multiple intrusive dykes and sills of dolerite, rhyolite, porphyritic granite and a polymict breccia pipe.

The main mineralisation is associated with a curved thrust structure with an average strike of 045° and dip of 45° southeast, curving from a northerly direction in the southwest to an easterly direction in the northeast. There are other more minor mineralised structures on different trends.

Hydrothermal alteration is common across the deposit area comprising silicification (everpresent), quartz-sericite-pyrite, potassic and propylitic. The quartz-sericite-pyrite alteration is most closely associated with the gold mineralisation.

The main mineralisation is structurally controlled by the curved thrust structure, with a thrust zone typically between 2m to 10m thick with heavily deformed cataclastic rocks with well developed quartz veins. Thin, high-grade gold veins are also found outside of the main mineralised vein.

Gold is typically found associated with pyrite and tetrahedrite (3% to 5% by volume), and is found in the form of fine grained free gold (>5µm), not locked within other sulphides, although some is found in gold and silver tellurides.

It should be noted that gold mineralisation is also present as placer deposits in the vicinity of the deposit, within the colluvial material.

In summary, the geology and major controls on the mineralisation appear to be well understood, aiding the ability to model the deposit effectively and appropriately. The deposit exhibits typical features of shear-zone gold deposits.

Mine access to the open-pits is via a single haul road developed as part of the starter pit and the final pit and extending from surface to a depth of 145m below surface. The open-pit is designed with the following parameters: 20m wide ramps with a gradient of 10% and overall slope angles ranging from 45° to 58°. Other final design aspects are: bench heights of 15m; batter angles of 75°; and berm widths of 8m.

Mining methods comprise standard drill-blast- load-haul with a total material moved capacity of 9.5Mtpa. Mining occurs by drilling and blasting 5m high sub-benches with 120mm to 200mm blast holes. Hydraulic excavators with 8.4m3 bucket capacities load blasted ore and 10.0m3 bucket capacities load waste into 80t rear-dump haul trucks. Additional service equipment comprise graders, tracked dozers, water trucks and general service vehicles.

Metallurgical Processing.
The Ad Duwayhi Plant processes ore mined from the open-pit operation. The process has comprises a comminution circuit, a parallel gravity circuit for recovery of coarse grained free gold and a CIL circuit followed by elution, electrowinning and smelting to produce gold in doré form for third party refining.

Processing Facilities.
RoM ore from the open-pit operations is crushed in a single stage primary crusher fed by loader which in turn will establish a live crushed primary ore stockpile. Following reclamation by conveyor, crushed ore is milled in a semiautogenous grinding mill (“SAG”) with pebble recycling and a ball mill operating in closed circuit. The combined SAG and ball mill discharge is pumped to hydro-cyclones to produce a nominally 80% passing 75µm product. Cyclone underflow is treated in a gravity circuit to recover free gold before recycling to the ball mill.

Slurry from the comminution circuit is thickened prior to leaching in a six stage CIL circuit ahead of elution (AARL circuit), electrowinning and smelted along with the gravity concentrates to produce doré.

Tailings arising from the CIL circuit is thickened and filtered to enable dry storage and minimise water usage.