Deposit Types
The zinc-copper-gold-silver bearing sulphide mineralization identified on the Back Forty Property exhibits typical characteristics of VMS mineralization. This deposit type has been well documented in the literature since the early 1970s (Franklin et al. 1981) and the exploration model for the PVB was refined after the discovery of Flambeau (DeMatties et al. 1996).

Mineralized Zones
Mineralization at the Back Forty Deposit consists of discrete zones of: 1) zinc or copper-rich massive sulphide (±lead), which may contain significant amounts of gold and silver, 2) stockwork stringer and peripheral sulphide, which can be gold, zinc, and copper-bearing (±lead/silver), 3) precious metal-only, low-sulphide mineralization, and 4) oxide-rich, precious metal-bearing gossan.

Massive Sulphide Mineralization
The Main Zone massive sulphide, which accounts for the vast majority of massive sulphide mineralization lies at the statigraphic boundary of these two rhyolite units. Rhyolite 1 lies stratigraphically below this sulphide horizon (footwall) while rhyolite 2 lies above the horizon (hanging wall). Another massive sulphide horizon, the Tuff Zone, is located at or near the upper contact of rhyolite 2 and the lower contact of an overlying package of tuffaceous and siliceous sediments. A possible third massive sulphide horizon, the Deep Zone, may represent a lower mineralized zone.

Main Zone Massive Sulphide
The Main Zone is composed of three separate massive sulphide bodies (referred to as the East, Hinge, and South Limb Zones) that form a plunging antiform and are considered the same horizon. These bodies are hosted by Rhyolite 1 (footwall) along and stratigraphically below their contact with Rhyolite 2 (hanging wall). The strata-bound Main Zone is enveloped locally by stockwork and semi-massive sulphide mineralization. Pervasive sericite and disseminated pyrite alteration as well as variable silicification are abundant and extend outward for an undetermined distance. This zone extends along strike for over 450 m in a west-southwest direction; it is up to 100 m wide and subcrops at its eastern end under thin (less than 10 m) glacial overburden and local Paleozoic sandstone. The stockwork-stringer and peripheral sulphide envelope grades outward into a semi-conformable disseminated (less than 10%) pyritic halo that extends throughout the entire altered Rhyolite 1 host unit for an undetermined distance. The zone has been extensively disrupted by variably altered quartz feldspar porphyry (“QFP”) intrusions.

Pinwheel Zone Massive Sulphide
The Pinwheel Zone occupies the northwest portion of the Deposit, located structurally along the gently north-dipping northern limb of the antiform and is truncated to the south by the E-W fault. Limited geochemical data suggests that this unit is in fact located along the contact between rhyolite 1 and rhyolite 2 and is therefore likely the equivalent to the Main Zone massive sulphide and represent a ‘faulted-up’ portion of the north limb of this important massive sulphide horizon. Massive sulphide mineralization on strike of the Pinwheel Zone has been traced for roughly 700 m to the west-southwest where the gentle north-dip of the unit steepens. It should be noted,however, that the massive sulphide mineralization is to some degree discontinuous and often has a ‘stacked’ geometry, and that numerous faults and shear zones have been encountered in the adjacent host rock. The geometry of this zone is likely complicated due to these structures.

Deep Zone Massive Sulphide
The Deep Zone is located north of one of the QFP dykes, juxtaposed against the South Limb Horizon. Recent geological and geochemical data interpretation suggests that the Deep Zone may be the down-dip continuation of the South Limb, where it has been folded and rotated. This interpretation leaves significant spatial potential for further Mineral Resource discovery between the South Limb and the Deep Zone as well as down dip of the Deep Zone.

Tuff Zone Massive Sulphide
The Tuff Zone massive sulphide occurs at the south edge of the Deposit. Stratigraphic and structural data suggest this zone is located at a higher level in the volcanic sequence. In cross sections and three-dimensional models, the zone appears to have a bowl-shaped geometry possibly reminiscent of a small relict depositional basin or local graben structure.

Massive sulphide mineralization of the Tuff Zones appears preferentially developed within coarser grained tuffaceous units at or near the contact of rhyolite 2 and of the overlying tuffaceous and siliceous sediments. Overall sulphide content is less massive than that of the Main Zone (~60%-80%) and is dominated by sphalerite, pyrite, and galena. The zone’s thickness is typically on the order of a couple of metres.

Mineralization Encountered at Depth
Mineralization has been encountered in two separate stratigraphic horizons which have tentatively been called the ‘Upper Deep’ and ‘Lower Deep’ zones. LK-479, drilled to the southwest of known mineralization and to a total depth of 911 m, encountered each of the two zones and represents the ‘discovery’ hole for each.

The upper mineralized section in drill hole LK-479 intercepted ~60 m of strongly altered rhyolite and tuffaceous and siliceous sediments with variable sulphide mineralization in the form of disseminated and stringer sulphides as well as two small intervals of high-grade massive sulphide. The mineralization was also cut by a quartz-feldspar porphyry dyke that contained PM-style gold mineralization. Assayed intervals (drilled thickness) within the section include: 12 m (366-278 m) of 1.25 g/t Au, 57.9 g/t Ag, 0.41% Pb, and 1.0% Zn and 12.8 m (407.3-420.1 m) of 4.27 g/t Au, 189.1 g/t Ag, 1.4% Pb, and 4.2% Zn. The metal content of this zone, as well as the spatial relationship to the tuffaceous and siliceous sediment unit would suggest that this zone may be related to the Tuff Zone type sulphide mineralization, however, limited and preliminary geochemical data indicates that the mineralization may reside at the contact of rhyolite 1 and 2 which would imply that this zone is related to Main Zone mineralization. It is also interesting that the high-grade massive sulphide encountered in this section appears to cross-cut bedding which would indicate that higher-grade mineralization may be related to a cross-cutting structure. A number of drill holes attempted to follow-up on this intercept and encountered similar mineralization in altered rhyolite and tuffaceous and siliceous sediments, but grades were typically less substantial than that of LK-479. The zone lies roughly 80 m along strike, to the southwest of the south limb of the Main Zone massive sulphide. The lower mineralized section in drill hole LK-479 intercepted roughly 68 m of massive sulphide overlain by stockwork stringer type mineralization. Metal content of the massive sulphide was generally zinc-poor with a relative

The mine plan consists of a combined open pit and underground mining operation. Open pit mining will take place from Year 1 to Year 5. Underground development will be initiated in Year 5 and underground production mining will continue to Year 11.

A number of stockpiles, by material type, will facilitate the accelerated processing of higher-grade material and also manage fluctuations in process plant feed delivery from the two mining operations.

The Back Forty Project area consists of very subdued terrain and topography. The area, topography and climate are amenable to the conventional open pit mining operations proposed for the Project. The open pit mining operation will encompass a single open pit that will be mined with conventional mining equipment in three pushback phases. The underground mine will be developed beneath the open pit with a single decline access point located part way down the open pit ramp.

The open pit design is based on the 2018 Feasibility Study. Minor modifications were made to standardize on 5 m high benches with a quadruple (4) bench configuration, resulting in a 20 m vertical distance between catch berms. For scheduling purposes, the Back Forty pit was subdivided into three phases. Mining commences in a small higher-grade pit and then expands outwards by pushing back the pit wall. This enables annual waste stripping quantities to be distributed to avoid high and low annual tonnage fluctuations.

Open pit mining operations will be carried out by Company personnel except for blasting. A blasting contractor will be used to supply the explosives, prepare the blasts, charge the holes, fire the blast, and inspect the area post-blast. The equipment fleet will consist of hydraulic excavators and front-end wheel loaders, both with 8 m3 buckets, and 90 t capacity haul trucks, plus track dozers, graders, and support equipment.

Mineralized material may be delivered either to the primary crushers or placed into one of the stockpiles. Waste rock is either taken to a waste rock storage facility or used in tailings dam construction. A six month pre-production period is planned.

Underground Mining
Extraction of the potentially economic portion of the underground Mineral Resource will be achieved by a combination of mechanized Cut and Fill (“CF”) or Longhole (“LH”) methods. CF mining is the dominant method, producing approximately 63% of mined tonnes, with LH producing the remaining 37% of tonnes. CF mining uses one of four stope sizes, and targets low-dipping material (dip less than 55°). LH mining uses one of two stope size subsets and orientations (transverse or longitudinal).

All waste and mineralized material development will be carried out using drill jumbos and mechanized bolting units, thus allowing for sharing of the equipment fleet between development and production assignments, allowing crews and machinery to perform production and/or development tasks in nearby mining areas while limiting machinery travel distances. Mineralized material will be extracted from the CF and LH stopes using 9 t and 14 t load-haul-dump (“LHD”) units and loaded into 40 t underground trucks for transport to surface.

Access to the Deposit is via a 5 m by 5 m ramp from surface, with the underground portal located on the 187.5 m pit bench. All development and production material from underground is hauled to, and dumped at, a portal stockpile. From the stockpile, open pit trucks will transport the material to its final destination. Backfilling of the stope areas is achieved through the use of Pastefill (“PF”), delivered via two boreholes from the surface PF Plant. PF varies from 3-7% cement by mass, depending on application: higher cement contents are used for artificial sill pillars, lower cement contents are used otherwise. The PF system has a planned capacity of 2,300 tpd and the PF Plant is to be operated for 16-18 hours per day on average. All stoping areas are planned to be filled with pastefill.

The underground construction and development commences in Q1 of Year 5, with production beginning at the start of Q3 of Year 5. Commercial production is achieved midway through Q4 of Year 6. The production rate of the underground varies depending on development requirements, with a nominal commercial production rate of 2,300 tpd, increasing to a maximum of 3,200 tpd in Year 7, before decreasing slightly towards the end of mine life in Year 9 as CF mining areas are exhausted and the mine transitions to lower-value LH stopes. LH mining for the Back Forty Deposit uses a nominal 25 m floor-to-floor sublevel spacing, with 5 m drift heights.

The underground mine is equipped with a high-capacity pumping system capable of moving 109 L/s to surface if necessary. Ventilation is provided via three powered fresh air raises, with the portal and a single unpowered return air raise for exhaust. Electrical power is supplied initially at 15 kV, with step-down transformers distributed throughout the mine. The mine also has a small compressed air distribution system capable of providing 0.45 m3/s at standard temperature and pressure.

The total mined and recovered portion of the underground Mineral Resource comprises 5,717 kt of mineralized material with an average Net Smelter Return (“NSR”) value of US$109.24/t. Figure 1.2 presents a 3-D schematic of the underground mine layout at the end of the life-of-mine (“LOM”). The green stopes are active in the final year of mining, and the blue stoping areas are mined out and filled.

Mining dilution is broken down into three types: Internal, External and Backfill. Average internal dilution is 13.6% by mass, average external dilution is 6.3% by mass, and average backfill dilution is 4.4% by mass. Overall mining recovery on a tonne-weighted basis is expected to be 93.4%.

The total mined and recovered portion of the underground Mineral Resource comprises 5,717 kt of mineralized material with an average Net Smelter Return (“NSR”) value of US$109.24/t.

A total of 22,805 m of lateral development and 1,169 m of vertical development are required over the underground LOM.

OXIDE CRUSHING CIRCUIT
A modular three-stage crushing circuit will be used to produce a product with a P80 of 8 mm, suitable for feeding a single stage ball mill.

Oxide Primary Crushing
The Run-of-Mine (“ROM”) loader will collect mineralized material from the ROM oxide stockpile and feed it into the coarse mineralized material bin via a grizzly. A water spray/glycolsystem will be installed at the coarse mineralized material bin for dust suppression purposes. The static grizzly will have a spacing of 600 mm to prevent the ingress of oversize mineralized material. A mobile rock breaker will be provided to assist in breaking down oversize material retained on the static grizzly. Mineralized material will be withdrawn from the ROM bin by a variable speed vibrating grizzly with a 40 mm aperture size. Oversize from the grizzly will report directly to the primary jaw crusher, which will operate in open circuit. Crushed product from the jaw crusher, along with vibrating grizzly undersize, will report to the oxide transfer conveyor.

The transfer conveyor will be fitted with a weightometer to monitor and control the crushing rate via the vibrating grizzly variable speed control. A static magnet will remove metal from the crushed mineralized material stream. Tramp metal will be removed manually. A metal detector will be installed near the head end of the transfer conveyor as a secondary safeguard.

Secondary and Tertiary Crushing and Screening
Primary crushed mineralized material will report to a secondary crusher feed bin from where mineralized material will be fed to the secondary crusher using a vibrating feeder. Secondary crusher product with a P80 of 14 mm will be conveyed to a double deck screen. This screen will be fitted with 16 mm aperture panels on the top deck and a 12 mm panels on the bottom deck. Oversize from the top and second decks will report to the tertiary crusher feed bin. This oversize material will be fed to the tertiary cone crusher using a vibrating feeder. Tertiary crushed product with a P80 of 10.6 mm will be conveyed back to the screen feed conveyor.

Oxide Grinding Circuit
The oxide grinding circuit will receive mineralized material at a nominal top size of 12 mm with a P80 passing size of 8 mm. The circuit will consist of a single-stage ball mill in closed circuit with a cyclone cluster. The ball mill will be a 2.90 m diameter x 4.60 m EGL overflow mill, with a 450 kW fixed speed motor. The mill will operate at a 32% ball charge. Mineralized material will be fed to the ball mill at a controlled rate, nominally 16.0 dry t/h, and water will be added to the feed chute to achieve the desired milling density. Hydrated lime will also be added to the mill feed to ensure adequate mixing and contact with the mineralized material surfaces.

Product from the oxide ball mill will discharge over a trommel, with oversize reporting to the scats bunker, where it will be periodically removed by skid-steer loader and returned to the circuit via the clean-up hopper. Trommel undersize will flow, by gravity, to the oxide cyclone feed hopper where it will be further diluted to achieve the required cyclone feed density. The oxide cyclone feed pump will deliver slurry to the cyclone cluster. Cyclone underflow will return to the oxide ball mill, while cyclone overflow will flow by gravity to the oxide trash screen. The cyclone cluster will consist of two operating 10-inch cyclones plus one installed spare and at least one blank nozzles.

SULPHIDE CRUSHING CIRCUIT
ROM mineralized material will be fed into the coarse mineralized material bin above the primary crusher via a front-end loader which will collect mineralized material from the ROM stockpiles or direct tip from the mine haul trucks. A water/glycol spray system will be installed at the coarse mineralized material bin for dust suppression purposes. The coarse mineralized material bin will include a static grizzly with a spacing of 600 mm to prevent the ingress of oversize material. A mobile rock breaker (shared with the oxide coarse mineralized material bin) will be provided to assist in breaking down oversize material retained on the static grizzly. Mineralized material will be withdrawn from the ROM bin by a variable speed vibrating grizzly with a 90 mm aperture size. Oversize from the grizzly will report directly to the primary jaw crusher, which will operate in open circuit. Crushed product from the jaw crusher, along with vibrating grizzly undersize, will report to the sulphide transfer conveyor.

SULPHIDE GRINDING CIRCUIT
The sulphide grinding circuit will receive mineralized material at a nominal top size of 208 mm with a P80 passing size of 100 mm. The circuit will consist of a SAG mill and a ball mill in closed circuit with a cyclone cluster.

The SAG mill will be a 6.10 m diameter x 3.60 m EGL mill with a 2,200 kW variable speed motor. The SAG mill will operate with 7.2% to 15.0% ball charge. Mineralized material will be fed to the SAG mill at a controlled rate, nominally 127.8 dry t/h, and sulphide process water added to the feed chute to achieve the desired milling density (70% solids). Hydrated lime will also be added to the mill feed to ensure adequate mixing and contact with the mineralized material surfaces while providing the correct alkalinity to the slurry. Product from the sulphide SAG mill will discharge over a trommel with the oversize reporting to the scats bunker where it will be periodically removed by the skid-steer loader and returned to the circuit via the clean-up hopper.

The ball mill will be a 4.50 m diameter x 6.85 m EGL overflow mill, with a 2,200 kW fixed speed motor. The mill will operate with between 16.3% and 36% ball charge. Product from the sulphide ball mill will discharge over a trommel, with oversize reporting to the rejects bin. Trommel undersize will gravitate back to the sulphide cyclone feed hopper to be classified again.

Grinding media for the sulphide mills will be introduced by use of a dedicated kibble and the grinding building maintenance crane. Three vertical spindle sump pumps, one located at the feed end of the mills, another at the discharge end of the mills, and the third one nearby the sulphide cyclone feed hopper will service the area. The concrete floor under the mill area will slope to the sumps to facilitate clean-up. In addition, a gold trap will be located in the gravity concentration area.

The oxide process plant has been designed for a throughput of 350 tpd (dry) at head grades of up to 8.0 g/t Au and 127 g/t Ag. The overall flowsheet includes the following steps:

• Three stage crushing using an open circuit jaw crusher, open-circuit secondary cone crusher and closed-circuit tertiary cone crusher.
• Grinding and classification.
• Pre-leach thickening.
• Cyanide leach.
• Vacuum filtration of leaching tailings.
• Sulphidization, Acidification, Recycle and Thickening (“SART”).
• Carbon-in-Column (“CIC”) gold adsorption.
• Carbon acid-washing, desorption and recovery (“ADR”).
• Smelting to produce doré.
• Cyanide destruction of the final wash filtrate from the vacuum filtration step.
• Tailings repulping and disposal to the TMF.

The sulphide process plant has been designed for a nominal throughput of 2,800 tpd (dry), with varying copper, lead and zinc head grades. The overall flowsheet includes th ........