The origin of gold deposits in the Malartic area is still a subject of controversy. Trudel and Sauvé (1992) favour an epigenetic model with structural and lithological control based on the association of high-grade gold mineralization and deformation zones throughout the camp.

According to Issigonis (1980) and Robert (2001), the gold deposits of the Malartic area are porphyry-related and possibly orthomagmatic in origin. The porphyries are generally considered to be syenitic (alkaline) in composition and of Timiskaming (syntectonic) age (Fallara et al., 2000; Robert, 2001).

Robert et al. (2005) include these deposits in a mineralization style named “disseminated stockwork zones”, which consists of zones of disseminated sulphides as fine, uniform disseminations or bands concentrated along foliation planes. The mineralization is often centred on small, shallow-level intermediate to felsic porphyry intrusions, many of which were emplaced in clastic sedimentary rocks.

Helt et al. (2014) adopted a magmatic-hydrothermal model that calls for the exsolution of an ore fluid from monzodioritic magma at mid-crustal levels. Gold is deposited during the fluid’s ascent while host rocks endured potassic, carbonate, sulphide and silica alteration. Thus, the porphyritic rocks that host some of the mineralization were not the source of the fluids. Instead, their contacts with Pontiac greywacke and Piché mafic and ultramafic rocks provided contrasts in competency that helped focus the mineralizing fluids.

More recently, De Souza et al. (2019) describe the Canadian Malartic deposit as a mesozonal stockwork-disseminated replacement-type deposit formed within an orogenic setting where the variable geometry, rheology and composition of the various intrusive and sedimentary rocks have provided strain heterogeneities and chemical gradients for the formation of structural and chemical traps that host the gold.

Mineralization
Mineralization in the Canadian Malartic deposit occurs as a continuous shell of 1 to 5% disseminated pyrite associated with fine native gold and traces of chalcopyrite, sphalerite and tellurides (Eakins, 1962; Fallara et al., 2000). It extends on a 2 km strike and a width of 1 km (perpendicular to the strike) and from surface to -400 m below surface. The gold resource is mostly hosted by altered clastic sedimentary rocks of the Pontiac Group (70%) overlying an epizonal dioritic porphyry intrusion. A portion of the deposit also occurs in the upper portions of the porphyry body (30%). The porphyry intrusion pinches out in the Sladen Malartic mine and disseminated mineralization continues in the silicified greywacke, forming a subvertical tabular body (Sladen Extension) that is truncated by the LLCFZ where it intersects the South Barnat Zone and merges into the western extremity of the East Malartic Zone.

Surface drilling by Lac Minerals in the 1980s defined several near-surface mineralized zones now included in the Canadian Malartic deposit (the F, P, A, Wolfe and Gilbert zones; Figure 7.3), all expressions of a larger, continuous mineralized system located at depth around the old underground workings of the Canadian Malartic and Sladen mines. In addition to these, the Gouldie mineralized zone occurs approximately 0.5 km southeast of the main Canadian Malartic deposit, although the relationship between these zones and the main deposit is presently unknown. The recently discovered East Gouldie deposit is located 2 km east of the Gouldie mineralized zone.

The semi-continuous shells of higher-grade mineralization (>1 g/t Au) at Canadian Malartic define an open synformal structure trending N110°E and plunging about N20° to the ESE. This structure closes at the western end of the deposit in the area of the F Zone and has been previously interpreted as a post-mineralization fold structure that has deformed the deposit (Derry, 1939; Derry and Herz, 1948; Fallara et al., 2000). For most of the Canadian Malartic deposit, mineralization along the northern limb of the fold follows the porphyry-greywacke contact. The structure becomes tabular with a steep dip to the south, where the porphyry body pinches out in the Sladen Extension. This extension of the deposit to the east represents the northern limb of the synform. A broad, sporadically mineralized shell of lower grade mineralization (0.2 to 1.0 g/t Au) forms a halo around the main deposit and is associated with potassic alteration.

Alteration in the sedimentary rocks of Canadian Malartic consists of biotite-sericitecarbonate (potassic alteration) overprinted by silica and carbonate. Carbonates include calcite and minor ankerite. Highly silicified zones adopt a “cherty” texture and are commonly brecciated. Potassic alteration in the porphyry consists mostly of alkalifeldspar replacement of plagioclase that is contemporaneous with minor quartz veining. Quartz replacement with minor carbonate also overprints potassic alteration in the porphyry. Late, coarse-grained, quartz-feldspar-muscovite veins mineralized with native gold form relatively small, higher grade stockworks along the northern edge of the deposit (Eakins, 1962; Derry,1939). Retrograde chlorite-calcite alteration of the previous assemblages, particularly the biotite, is found throughout the deposit but is particularly intense along ductile shear zones, forming chlorite-calcite schist.

The South Barnat deposit (also identified as the “Barnat deposit” in the context of open pit resource and reserve estimation) is located to the north and south of the old South Barnat and East Malartic mine workings, largely along the southern edge of the LLCFZ. The portion of this deposit that is originally modelled for surface mining evaluation extends on a 1.7 km strike and a width of 900 m (perpendicular to the strike) and from surface to -480 m below surface. The original South Barnat deposit of Barnat Mines Ltd represents the northwesterly extension of the East Malartic mine. South of the fault contact, gold mineralization occurs as disseminated mineralization and stockwork hosted in potassic-altered, silicified greywacke units of the Pontiac Group. North of the fault, it occurs as disseminated mineralization and stockwork hosted in both potassic-altered porphyry dikes and carbonatized, biotite-rich schistose ultramafic rocks. Porphyry dikes on both sides of the fault, but especially abundant on the north side, contain disseminated mineralization as well as late quartz veins locally containing visible gold. A mineralized zone developed along the Sladen fault connects the Canadian Malartic and the South Barnat deposits.

The East Malartic deposit (as modelled for the underground mining model) has been previously mined by the East Malartic, Barnat and Sladen mines mainly along the contact between the LLCFZ and the Pontiac Group sedimentary rocks. This deposit includes the deeper portion of the South Barnat deposit (below actual pit design). The portion of this deposit that is modelled for the underground mining evaluation extends on a 3 km strike and a width of 1.1 km (perpendicular to the strike) and from the bottom of the South Barnat actual pit design to –1,800 m below surface. The old mining infrastructures and stopes follow local and regional fault zones, pyrite-enriched environments, silica-calcite and potassic alteration zones, and porphyritic intrusions. The geological settings are similar to what is found in other areas of the Property, corresponding mainly to the deep extension of the geological context presented above for South Barnat (open pit deposit).

Mining at the Canadian Malartic mine is by open pit method with excavators and trucks, using large scale equipment. The primary loading tools are hydraulic excavators, with wheel loaders used as a secondary loading tool. The current mine production schedule was developed to feed the mill at a nominal rate of 57,000 tonnes per day. The continuity and consistency of the mineralization, coupled with tight definition drilling, that has been confirmed by many years of mining operations, demonstrate the amenability of the mineral reserves and mineral resources to the selected mining method.

Waste material is stored north of the TSF. An estimated total tonnage of 450 Mt of waste will be placed on the waste rock pile. An in-situ compacted density of 1.96 t/m3 was used to estimate the storage volume of 230 Mm3.

The ramps and haul roads are designed to accommodate the largest equipment, which is currently the Caterpillar 793F haul truck. For double-lane traffic, provincial regulations are followed. Double lane roads are designed for all accesses. Optimization to complete mining at the bottoms of pits is planned to be single lane. The travelling surface is at least triple the width of the largest vehicle. Ramp gradients are designed at 10%.

The open pit mine life is planned to extend to 2029, with mining continuing to transition from the Canadian Malartic pit to the Barnat pit. Production will transition from the open pit to the underground between 2023 to 2029. Annual gold production attributable to Yamana is expected to be approximately 320,000 ounces in 2022, 330,000 ounces in 2023, and 340,000 ounces in 2024. The Odyssey underground project supports a mine life to at least 2039 with annual gold production of 500,000 to 600,000 ounces when fully ramped up on a 100% basis. Opportunities exist for supplemental production sources to increase throughput beyond the 20,000 tpd as outlined in the Technical Study (as defined herein) and utilize the excess process capacity of the 60,000 tpd Canadian Malartic plant. Exploration drilling of the East Gouldie Extension and parallel structures, while widely spaced, indicate that a corridor of mineralization extends at least 1.3 kilometres to the east of East Gouldie. Although at the very early stages, these results suggest the potential for a second production shaft that could increase throughput over the longer term. Open pit and underground exploration targets within the Canadian Malartic land package present additional potential ore sources.

Following the completion of an internal technical study in late 2020, the Partnership has approved construction directly to the east of the Canadian Malartic/Barnat pit of a new underground mining complex named the Odyssey project, which hosts three main underground mineralized zones: East Gouldie, East Malartic and Odyssey, the latter of which is sub-divided into the Odyssey North, Odyssey South and Odyssey Internal zones.

In December 2020, ramp development was started on the Odyssey project in order to facilitate underground conversion drilling in 2021 and provide access to the Odyssey and East Malartic deposits.
Production via the ramp is expected to begin at Odyssey South in late 2023, increasing up to 3,500 tpd in 2024. Collaring of the shaft and installation of the headframe is expected to commence in the second quarter of 2021, with shaft sinking activities expected to begin in late 2022. The shaft will have an estimated depth of 1,800 metres and the first loading station is expected to be commissioned in 2027 with modest production from East Gouldie. The East Malartic shallow area and Odyssey North are scheduled to enter into production in 2029 and 2030 respectively.

Mining at the Odyssey project will be done using underground methods. The mine design at the Odyssey project includes a 1,800 metre deep production-services shaft with an expected capacity of approximately 20,000 tonnes per day. Mining activities are expected to primarily use a sublevel open stoping mining method with paste backfill. Longitudinal retreat and transverse primary-secondary mining methods will also be used dependent on mineralization geometry and stope design criteria. The project is expected to use a combination of conventional and automated equipment, similar to what is currently used at the LaRonde Complex.

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The processing plant has a nominal capacity of 55,000 tonnes of ore per day.

Ore is processed through conventional cyanidation. Ore blasted from the pit is first crushed by a gyratory crusher followed by secondary crushing prior to grinding. Ground ore feeds successively into leach and CIP circuits. A Zadra elution circuit is used to extract the gold from the loaded carbon. Pregnant solution is processed using electrowinning and the resulting precipitate is smelted into gold/silver dore bars. Mill tails are thickened and detoxified using a Caro acid process, reducing cyanide levels below 20 parts per million. Detoxified slurry is subsequently pumped to a conventional tailings facility. The end of life of the tailings storage facility is estimated at the end of 2023 with the addition of the PR7 cell. From 2024 onwards, the tailings are expected to be pumped into the Canadian Malartic pit.

PLANT
The slurry is thickened to an average of 53% solids in the pre-leach thickener before being fed to the leach circuit. The leach tanks are located outside and consist of four series of five tanks in parallel with agitators. Oxygen is added to raise the oxygen level in the solution phase in order to maintain the leach kinetics. From the leach tanks, the slurry flows by gravity to the CIP circuit. The circuit is composed of two parallel sets of Kemix CIP pump cell carousel systems. Each cell contains approximately 13 t of carbon. The loaded carbon and slurry are pumped from the cell in the first stage of the carousel circuit to a loaded carbon screen where the carbon is separated from the slurry. The slurry returns to the second stage cell of the carousel while the loaded carbon is transferred to the stripping vessels by gravity.

The Split-Zadra process is used to extract the gold from the loaded carbon. The caustic solution is heated to about 140°C and is then passed through the pressurized stripping vessel that strips the gold from the loaded carbon and sends it into the stripping solution. The solution is sent to the electrowinning circuit where gold is plated onto stainless steel wool cathodes. The plated gold is pressure washed from the cathodes and then filtered, dried and sent to a refining furnace where the gold is poured into doré bars. The bars contain a significant amount of silver that is recovered along with gold.

The stripped carbon is transferred to the carbon reactivation kilns, where it is reactivated by heating it to about 800°C in a reducing atmosphere. The carbon is then re-used in the CIP circuit. Fresh carbon is regularly added to make up for attrition losses. The activated carbon is pumped to the tank in the CIP that has been emptied when the loaded carbon has been removed to start a new tank in the carousel. Before being added to the last tank in the carousel series, the carbon is screen do ensure that no fine particles of carbon are introduced into the circuit.

The slurry flowing from the last tank in the carousel series is barren of gold and is considered as tailings. This slurry is discharged over linear safety screens as insurance against coarse carbon losses from the circuit. The slurry is thickened to approximately 63% solid in the tailing thickener. The thickened tailings slurry is pumped to the detoxification plant where the total cyanide content is reduced to less than 20 ppm using Caro’s acid. The detoxified slurry is subsequently pumped to the tailings retention ponds, where most of the water drains out to be reclaimed back into the process.