The Seabee mine, Santoy mine, and Porky deposits host mesothermal, quartz-vein hosted lode gold deposits developed in major brittle-ductile to ductile shear systems. The gold mineralisation throughout the SGO exhibits complex geometrical patterns attributed to a combination of structural and/or lithological controls.

Mesothermal gold deposits typically emplaced as a system of en echelon veins, forming tabular veins in competent host rock lithologies, or as stockwork veinlets and stringers in less competent host rock lithologies. Lower grade bulk-tonnage style mineralisation with gold associated with disseminated sulfides may develop in areas peripheral to quartz veins. Mesothermal gold deposits can also be related to broad areas of fracturing, where gold and sulfides are associated with quartz veinlet networks. The quartz veins are typically in sharp contact with the wall-rock and can display a variety of textures including massive, ribboned or banded, and stockworks with anastomosing gashes and dilations, which may subsequently be altered or destroyed during deformation. Gold-quartz veins are found within zones of intense and pervasive carbonate alteration along faults proximal to trans crustal breaks, and often occur at a high angle to the primary collisional fault zone. They are commonly associated with late syn-collisional, structurally controlled intermediate to felsic magmatism, with economic deposits generally hosted by large competent units, such as intrusions or blocks of obducted oceanic crust (Ash and Alldrick, 1996).

Delaney (1992) suggested that lithological heterogeneities between feldspar porphyry dikes and gabbros of the Laonil Lake Intrusive Complex are responsible for the localisation and propagation of the shear zone. At Seabee, the structures trend between 045° to 085°, and dip north near vertically. Three discrete subsets of structures have been recognised trending at 070°, 085°, and 045°, with the 070° structures containing the auriferous veins. At Santoy, the structures trend between 340° to 315°, and dip moderately to the east. Vein geometry within the shear zones are commonly a combination of ‘S’ and ‘Z’ oblique and extensional types, and second order or Riedel shears.

The SGO is located within the northern portion of the Pine Lake greenstone belt. The belt has a strike length in excess of 50 km and comprises a variety of geochemically distinct tholeiitic mafic volcanic rocks formed in juvenile island arc settings, along with contemporaneous mafic intrusive rocks, volcaniclastics, sediments and felsic intrusions of varying age. Metamorphic grade across the Pine Lake greenstone belt ranges from upper greenschist to upper amphibolite, with the SGO hosted in the latter. The belt has been complexly folded by at least four major phases of deformation that are observed across the SGO site and elsewhere in the Glennie domain.

The SGO can be subdivided into three main geological domains:
• Seabee mine: The Seabee mine area is hosted within a coarsely layered mafic intrusion dominated by gabbro in the mine sequence.
• Santoy: The Santoy mine area is hosted within a sequence of mafic volcano-sedimentary rocks variably intruded by granodioritic rocks and separated by generally north–south trending thrust faults.
• Porky: The Porky deposit area is a mineralised trend hosted along a 12 km long openly folded unconformity, separating arenaceous sedimentary rocks of the Rae Lake synform to the north from mafic volcanic rocks of the Seabee mine area to the south.

Gold mineralisation at the (now ceased) Seabee mine is hosted within an extensive network of sub- parallel shear structures, which crosscut the Laonil Lake intrusive complex. Vein mineralogy is dominantly quartz with pyrite, pyrrhotite, and chalcopyrite, and accessory tourmaline and carbonate. Gold occurs primarily as free, finely disseminated flakes and films replacing pyrite or at sulfide boundaries. Higher grade gold values are most often associated within sulfide-rich zones or at vein junctions. Silicification is the most common alteration type observed at the Seabee mine.

Gold mineralisation at the Santoy mine is hosted within calc-silicate altered shear structures with diopside-albite ±titanite-bearing quartz veins and occurs in gold-sulfide-chlorite-quartz veins in the shear zones, near or in the granodiorite and granite sills. Diopside-albite calcsilicate alteration facies are the main host to gold mineralisation in the Santoy 8A and Santoy 9A, 9B, and 9C zones. The Gap Hangingwall (GHW) deposit is hosted within a shallowly dipping, north plunging, folded limb of the Lizard Lake Pluton. Mineralisation is concentrated near the fold hinge within cm to m scale quartz veining which strikes roughly north south and dip sub-vertically.

In the Porky deposit, the brittle-ductile lode gold system is hosted along a thick corridor of calc-silicate altered mafic volcanic and arenaceous sedimentary rocks that straddle a major unconformity along the southern margin of the Rae Lake synform. Both the Porky Main and Porky West deposits are characterised by the same calc-silicate alteration package, however, the unconformity and arenites host most of the auriferous quartz veins at the Porky West deposit.

Actual data and current operating practice are referenced heavily as the mine plan is based on the successful continuation of current practice. Mining at Seabee is now complete therefore all mining references relate to the Santoy mine.

The mine plan was initially completed by the SSR technical department on site at the Seabee Gold Operation (SGO) and included plans for the overall extraction of the Mineral Resource. OreWin has since reviewed the mine plan and made the appropriate modifications to include extraction of only the Mineral Reserve.

The LOM plan of the Mineral Reserve at SGO, commencing 1 January 2022, includes 2.68 Mt at an average grade of 6.7 g/t Au. The Mineral Reserve estimate includes dilution from hangingwall and footwall overbreak based on ongoing stope reconciliation. A total of 580 koz of gold will be delivered to the mill.

Access underground at the Santoy mine is provided from surface at the Santoy portal via a main ramp, with sublevels spaced between 17–20 m vertically. Mining is carried out using sublevel open stoping mining methods with backfill.

Stopes are filled with a combination of rock fill (RF) and cemented rock Fill (CRF), mined in a bottom-up mining sequence. Sill pillars are mined on retreat once the stopes below and above have been mined (stopes above filled with CRF and allowed to cure).

Mining factors are derived from ongoing analysis of site performance data.

Ore is trucked to surface and dumped on a surface mine ore pad. Ore is then loaded into surface trucks for a 14.0 km haul to the run-of-mine (ROM) stockpile at the mill, located at the old Seabee mine.

The primary mining method at the Santoy mine is longitudinal retreat (longhole open stoping). Avoca mining (which is similar in its process) is also used when access from both sides of the sill is available. The minimum mining width is 1.8 m. Planned stopes typically range in width from 3.9 m to 9.0 m. The length of the stopes varies based on deposit geometry and geotechnical guidance. Typical stope extents range from 20 m to 30 m along strike, with a maximum stope strike length of 40 m. External dilution is included based on ongoing stope reconciliations using actual mucking and cavity monitor survey data.

Level spacing varies from 17–20 m (vertical), floor-to-floor. The sill drifts on the levels are connected to a ramp to permit access for the rubber-tired mobile equipment fleet.

Longhole drills are used to drill down from the top level to breakthrough into the bottom level of the stope.

For localised areas with minimal strike length, Alimak mining methods, or captive longhole mining methods, are used to reduce lateral development costs. Access to the captive stopes is provided via an Alimak raise. Where the stope extends less than 15 m from the Alimak raise, production drilling is completed from the Alimak raise climber. For larger stopes, sub-drifts are driven to permit access for a longhole drill.

On completion of mining, stopes are backfilled with development waste rock. A cemented waste rock rib pillar is placed when mining occurs adjacent to backfill stopes. Based on stope sequence and long-term access requirements, some stopes can be left open without backfill.

Primary access is provided via a main ramp from the surface to the deepest levels. The main ramp begins at the Santoy portal, which is located at the top of the Santoy 8 deposit. Depending on the geometry of the deposit, the main ramp splays into secondary ramps to access longitudinally separated sections of the mine. The ramps are driven 5.0 m wide x 5.0 m high to permit access for the 45 t haulage trucks. Extensions to the existing ramps and additional ramps will be driven to provide access to planned mining levels.

Mining levels are driven from access crosscut drifts from the ramps. A standoff distance of at least 25 m from the ramp to the orebody is used when accessing from the footwall side, and 20 m when accessing from the hangingwall side. Typical level infrastructure excavations include a sump and a truck dump / remuck. Some levels include a drift to access and transfer ventilation from the levels above or below. Access to the longhole stopes is accomplished with sill drifts driven from the access crosscuts. The sill drifts are used for deposit definition, production mucking, and production drilling. The sill drifts are driven 4.2 m high with the width varying to suit the width of the ore (minimum 4.6 m), to a maximum of 8 m.

For a typical Alimak stope, level development consists of a haulage drift, a sill drift, and an Alimak chamber on the lower level and an access drift on the upper level. Temporary excavations are openings that are typically only used for less than two years before they are shut down or backfilled.

The run of mine ore is crushed in the mill yard in a portable style crushing plant. Primary crushing is carried out with a jaw crusher followed by cone crushing in closed circuit with a triple deck screen. The product from the crushing circuit, at minus 20 millimetres, is conveyed to the ore storage bin. To increase the storage capacity between the crusher and the grinding circuit, and allow for crusher breakdowns or scheduled maintenance, fine crushed ore is stockpiled in the yard and fed into the circuit through the original crushing feed point.

The grinding circuit consists of a ball mill 2.9 metres in diameter and 3.7 metres long serving as the primary grinding mill. Two secondary mills, 2.7 metres in diameter and 2.6 metres long, complete the grinding to 80 percent passing 200 mesh. The grinding mills operate in closed circuit with hydrocyclones. The ground product is thickened to 47 percent solids in a 12-metre thickener prior to entering the leach circuit.

Cyanide, at the rate of 0.72 kilograms per tonne, and lime at 0.27 kilograms per tonne, is introduced to the flow in the grinding circuit to maintain the pH and free cyanide levels for optimum leach conditions.

The mill flow sheet is a conventional crushing and grinding circuit employing gravity gold recovery and cyanide leaching with carbon-in-pulp (CIP) for recovery and production of doré gold on site.

The mill maintains a high availability and routinely averages more than 94% operating time with the average monthly rate from 2014 to the present being 94.6%. Currently, an addition to the gravity recovery circuit is being installed that will increase the gravity gold recovery and reduce the limitations of the main cyanide leach circuit.

A portion of the cyclone underflow on the primary grinding mill is directed to a Knelson concentrator for further concentration on a vibrating table. The gravity concentrate, averaging approximately 65% of the total gold recovered, is refined with the gold recovered in the hydrometallurgical circuit.

The gravity recovery circuit consists of two Knelson concentrators and an Acacia reactor, which recovers the gravity gold in a ........