Zgounder is a Neoproterozoic age, sedimentary rock-hosted, low-sulphidation epithermal silver deposit.

The Zgounder Silver Deposit is cross-cut by fractures of variable orientations. There are at least four (4) fracture systems:
1. Late sub-vertical E-W fractures and shear zones;
2. N-S fractures/faults dipping steeply to the east;
3. NNE-NNW-oriented system dipping 60° at a strike of 75°E; and
4. A sub-horizontal system of fractures oriented NNE and NNW, which displaced the Brown Formation to the north with depth (Bounajma, 2002).

Mineralisation
The Zgounder silver mineralisation occurs at the top of the Brown Formation (sandstone), predominantly along the contact and within the dolerite sill. The economic silver concentrations at Zgounder are present mainly as vertical bodies, complex clusters, shear zones, and veinlets, and at the intersection of the E-W and N-S fractures, though preferentially at the contact zones between schist and dolerite (Petruk, 1975; Popov et al., 1989). Native silver occurs in complex sets of microfractures, mainly at intersections with sulphide veinlets, and locally accompanied by chloriterich alteration. Small Ag grains (average size = 50 µm) occur in corrosion zones of early sulphides or disseminated within the schist and dolerite.

According to Marcoux et al. (2015), the paragenetic sequence shows two successive stages of mineralisation: 1) an early Fe–As stage and 2) an Ag-bearing polymetallic (Zn–Pb–Cu–Hg) stage. The early-stage mineralisation is composed of pyrite (70.3%) and arsenopyrite (6.1%). Pyrite shows rare silver inclusions (20 µm). The late polymetallic stage of mineralisation consists of dominantly sphalerite (17.9% of the mineralised material). Electronic microprobe data suggest the presence of two generations of sphalerite: an iron-free generation (<1% Fe) and an iron-rich generation (up to 8% Fe). Silver has not been detected in the sphalerite. Chalcopyrite is rare (1.8% of the mineralised material), carrying very rare Ag-poor grey copper patches (<40 µm), and Ag-free galena (2.3% of the mineralised material).

Native silver is by far the most common silver mineral, representing 1.07% of mineralised material concentrate, and 65% to 90% of Zgounder silver. The native silver is Ag–Hg amalgam, rather than pure silver, forming inclusions 25 µm to 480 µm in size (average 150 µm to 250 µm). Electronic microprobe analyses (Marcoux and Wadjinny, 2005) revealed presence of two (2) generations of large Ag-rich patches containing 85% to 95% Ag (average structural formula Ag17Hg), which likely corresponds to remobilisation slightly post-dating the major silver mineralisation event. The latter is characterised by smaller silver blebs containing 72% to 80% Ag (Ag5Hg, similar to that of eugenite), which represent the majority of the native silver mineralisation at Zgounder. Native silver patches show irregular variation of Hg grade and grain size (up to 1,920 µm), and carry myriads of native silver inclusions (<5 µm). Small patches of polybasite (Ag16Sb2S11) and pearceite (Ag16As2S11) are rare. Tennantite and tetrahedrite are very rare phases. Silver contents are variable, but low (average: 4% Ag). Acanthite (Ag2S) is the main silver sulphide, but is much less abundant than native silver and contains inclusions of native silver (Marcoux et al., 2015).

Tension gashes originally trapped the silver mineralisation within a NNE-oriented shear zone affecting the shale-sandstone beds (Brown Formation) that contain anomalous Ag values. The silver was likely remobilised by E-W oriented structures forming isolated Ag-mineralised lenses and fissures (Figure 7.11). The silver mineralisation extends laterally over 1,000 m and dips sub-vertically to the south. Vertical mineralised zones are offset by sub-horizontal faults with a northward movement of 10 m to 30 m, creating steps or blocks of mineralisation (Bounajma, 2002).

Based on lead isotope ratios (²°6Pb/²°4Pb = 17.89 and ²°7Pb/²°4Pb = 15.57) measured on galena grains from the polymetallic stage of silver mineralisation, the calculated age for the Zgounder Silver Deposit is approximately 510 Ma (Marcoux and Wadjinny, 2005), using the Stacey and Kramers (1975) model. The Zgounder lead isotopic ratios are similar to those measured at Imiter (²°6Pb/²°4Pb: ˜18.10; ²°7Pb/²°4Pb ˜15.5), with a mineralisation age of approximately 550 Ma (LateProterozoic; Pasava, 1994; Cheilletz et al., 2002). The similar ages of Zgounder and Imiter (eastern Anti-Atlas, Morocco), imply that the former is another example of a Neoproterozoic epithermal deposit in the Anti-Atlas of Morocco (Baroudi et al., 1999; Essarraj et al., 1998).

The Zgounder deposit is located in competent rock and has a steep overall dip. The historic mining method used at Zgounder is shrinkage stoping. To increase selectivity and ore recovery the cut and fill method is under development for new mining stopes. The main ramp is at the 2,000 m level and connects all existing levels to the east above the 2,000 m up to 2,100 m level. An access ramp from the 2000 level to the 1975 lever was also built. In the future, another access ramp to the 1,800 m level below the 2,000 m level will be built to reach the developed levels down to 1,925 m and the future levels down to 1,800 m. This will facilitate the development and the transportation of backfill when required above 2,100 m elevation.

Aya significantly changed its mining operations at Zgounder in 2021 by moving from a shrinkagestope mining method to a cut-and-fill method. Furthermore, increased mechanization began in 2021 with the introduction of the mine’s first jumbo.

As the mine has previously been in production, few new developments are required above 2,000 m. The total of additional development required is estimated at 20% of mineralized material tonnage with an average of 3.0m linear meters per working day. There is a provision in the sustaining capital for an average of 6.0m linear per working day, including the ramp (3.4m x 4m section), for a total of 4,691m for the major access and a 315m internal shaft for the life of mine (“LOM”). According to the historical and current mine production, the mining dilution is 10% and the mining recovery is 97%.

On February 22, 2022 the Corporation announced positive results from its Feasibility Study to expand the Zgounder Silver Mine located in the Kingdom of Morocco from 700 tpd to 2,700 tpd capacity.

The Zgounder Project will be mined in a combination of open pit mining, reclamation of historical tailings, and underground mining.

Open Pit Mining
Conventional open pit mining with 8x6 trucks and matching shovels, undertaken by a local mining contractor, was chosen for open pit portion of the Zgounder mine. The material extracted from the pit will be loaded into 8x6 trucks and hauled to its destination. The pit will be mined over a 7-year period, with two years of pre-production mining and an additional year for stockpile rehandling at the end of the mine life.

Ore material will be sent to either the ore pass or an ore stockpile; the stockpiles will separate the low-grade and high-grade material. Rehandled stockpile material will be loaded onto the trucks and brought to the ore pass. Waste material will be sent to the waste stockpile located near the pit. Some waste material will be sent underground for use in backfill.

The mine will be operated by a local mining contractor, who will supply all equipment and staff necessary for the operation.

Underground Mining
The underground mine will be mined using a combination of drift-and-fill and long-hole stoping. The underground mine will be accessed from surface and from the historic underground drift excavations that will require rehabilitation. The main ramp will begin from the underground on 2000L main level and be excavated up and down to the 2092L and 1648L Levels, respectively.

The development of the underground mine will be undertaken by mining contractors while the ore production will be undertaken by Aya staff. The underground operation will be undertaken over 11 years.

EXISTING FLOTATION PLANT
Run-of-mine ore containing 2.5% moisture content, is fed into a bin either by haul trucks or by a front-end loader. The mineralized material is withdrawn from the bin by a feeder to feed a 75-kW primary jaw crusher. The jaw crusher crushes the mineralized material, which is then conveyed to a dry crushing product screen with two decks. The oversize of the top deck falls by gravity into a 37-kW jaw crusher. The crushed product from this smaller jaw crusher is combined with the screen bottom deck’s oversize. Both streams combined are conveyed to a 160-kW secondary cone crusher.

The secondary cone crusher product combines with the primary jaw crusher product and is circulated back to the double-deck screen in closed circuit. This screen undersize is the crushed product from the crushing area and is conveyed to a crushed mineralized material stockpile.

From the crushed mineralized material stockpile, the product is reclaimed by vibrating feeders to be conveyed to the primary grinding circuit. This circuit comprises of a 320-kW primary ball mill, which operates in closed circuit with a spiral classifier. The overflow product from this primary grinding circuit contains the fines and is transferred to a secondary grinding circuit.

The secondary grinding circuit consists of a 280-kW ball mill in closed circuit with a cyclones cluster. The primary grinding circuit product combines with the secondary ball mill discharge into a pump box. The slurry is pumped to the cyclones cluster. The purpose of this last grinding step in the existing process plant, is to reach the final particle size for the flotation process. The cyclones underflow is reground in the secondary ball mill, whereas the cyclones overflow gravitates to an agitated tank.

EXISTING CYANIDATION PLANT
Silver mineralized material from the mine is crushed using a 55-kW jaw crusher and a 75-kW cone crusher.

Crushed mineralized material is stored in two silos, each dedicated to the two (2) identical production lines (North and South). The crushed mineralized material is further reduced in size by being conveyed to a grinding circuit in closed-circuit with cyclones. The pump box receives the 132-kW ball mill discharge and a downstream thickener overflow. The slurry is pumped to the cyclones where the underflow is fed to the ball mill feed chute along with the conveyed crushed ore from the silo. The cyclones overflow is transferred a thickener prior to cyanidation.

On February 22, 2022 the Corporation announced positive results from its Feasibility Study to expand the Zgounder Silver Mine.

The new mineral processing facility has been designed to treat mineralised material at a nominal throughput rate of 2,000 t/d and at a head grade of 210 g/t of silver.

The processing complex at Zgounder will comprise of the following three (3) facilities:
1. Existing Pant #1 (cyanidation plant);
2. Existing Plant #2 (flotation plant); and
3. New Plant #3.

Products from the existing plants will be processed by the new facility. The existing Plant # 1 (Cyanidation Plant) will continue to treat 180 t/d of mineralised material feed and its silver sludge will be transferred to the New Plant #3 for refining. The existing Plant # 2 (Flotation Plant) will continue to treat 500 t/d of mineralised material and it will produce a concentrate slurry which will be pumped to the New Plant #3 for leaching and refinery. Additional ........