The majority of the Project area is underlain by gentle to moderately southward-dipping rocks of the Belt Supergroup. The Belt Supergroup lithofacies are juxtaposed against gently south-dipping Cambrian sedimentary rocks along the VVFZ. To the north of the Project area, Belt Supergroup rocks are also exposed, below the basal Cambrian unconformity. Intermediate to mafic, Early Tertiary intrusive dykes and sills occur within the Belt Supergroup. Late Tertiary sedimentary lithofacies unconformably overlie all other units in the area.

Potentially economic Cu mineralization has been identified in the Newland Formation at the UCZ and the LCZ. The mineralization in both of these deposits is largely hosted by massive sulphide units referred to as the USZ and LSZ, respectively. Although not included in the MOP application, Cu mineralization also occurs at Lowry situated 3 km SE of the Johnny Lee deposit (Figure 7.2). Mineralization at Lowry is hosted by the LSZ and the MSZ. In order to discriminate between Johnny Lee and Lowry, the MSZ and LSZ at Lowry are herein referred to as Lowry Middle Sulphide Zone (LMSZ) and Lowry Lower Sulphide Zone (LLSZ). Mineralization at Lowry that occurs in these zones is referred to as the Lowry Middle Copper Zone (LMCZ) and Lowry Lower Copper Zone (LLCZ).

Johnny Lee Lower Copper Zone
The LCZ occurs at depths of 340 to 520 m below surface, strikes approximately EW and dips at 15° to 30° to the south. Mineralization in the LCZ is primarily hosted by the LSZ located in the FW of the VVFZ and HW of the Buttress Fault. The LSZ is overlain by a unit comprising interlayered shale and conglomerate and is underlain by a conglomerate unit. The LCZ deposit comprises three lenses of mineralization termed the East, Central, and West Lenses. These lenses are defined by the outer limit of >2.0% Cu mineralization which extend outside of the LSZ into the HW intercalated conglomerate and shale unit. Minor Cu mineralization also occurs in the conglomerate below the LSZ but does not exceed 2.0% Cu.

Johnny Lee Upper Copper Zone
The north-eastern corner of the UCZ is exposed on surface and the top of the mineralized zone extends to a depth of 210 m below surface. The high-grade portion of the UCZ (>1.2% Cu) is entirely encapsulated by the USZ although >0.25% Cu Halo mineralization extends into the shale that is located in the HW and FW of the USZ. The UCZ is gently folded by a W/NW plunging syncline-anticline pair such that strike is variable and dip ranges between 0° and 20°. With the exception of its extreme north-eastern corner, the UCZ is situated below the level of surficial oxidation. Acidic groundwater, preferentially focused along a layer parallel, brittle-ductile shear zone, resulted in localized supergene alteration of copper sulphides below the base of oxidation. The volume of supergene altered copper sulphide minerals along the shear zone is generally low, except at the junction of the shear zone with Fault 1.

Lowry Middle Copper Zone
The LMCZ is hosted by a succession of ferruginous sediment (massive sulphide and ferruginous shales) with interbedded conglomerate, carbonaceous shale and shale lithofacies. Three zones of >1.2% Cu mineralization occur in the LMCZ, termed LMCZ Vein 1 – LMCZ Vein 3. These mineralized zones dip to the south at 25 - 30°. The >1.2% Cu zones are surrounded by a zone of >0.25% Halo mineralization. The northern tip of the LMCZ occurs at 245 m below surface and the southern tip occurs at 755 m below surface. The LMCZ is situated below the depth of surficial oxidation. The LMCZ has plan view dimensions of 830 m (NS) by 280 m (EW). The maximum true thickness of the LMCZ is 45 m and it progressively reduces in width and pinches out to the north, south, east, and west.

Mineralization in the LMCZ occurs in both massive sulphide and the interlayered clastic sediment. Pyrite + Marcasite concentrations of typical mineralized intersections range from 9.1 – 45.2% and gangue mineral contact ranges from 38.7 – 76.0% (McArthur, 2019). Copper sulphide mineralization is predominantly chalcopyrite (8.3 – 17.0% in typical mineralized intersections) with minor tennantite (0.01 – 0.23%) observed in 30% of mineralogical samples studied to date (McArthur, 2019). The amount of primitive pyrite in the LMCZ ranges from 10.4 – 60.0% (average 49.1%) which is lower than that of the northern part of the UCZ (average 62.7%) indicating that the amount of recrystallization in the LMCZ is higher than that of the northern part of the UCZ.

Lowry Lower Copper Zone
The LLCZ occurs in the FW of the VVFZ (Figure 7.27) and both the host and mineralization is truncated in the SE by the Volcano Valley FW Fault. The LLCZ is hosted by a succession of ferruginous sediment (massive sulphide and ferruginous shales) with interbedded shale and conglomerate lithofacies. Two bedding-sub-parallel zones of >1.2% Cu mineralization occur within the LLCZ: LLCZ Vein 1 and LLCZ Vein 2.

The Black Butte Copper Project deposits exhibit attributes of both Sedimentary Exhalative sulphide deposits (SEDEX deposits, e.g. Emsbo et al, 2016) and Sediment-hosted Stratabound Copper (SSC) deposits (SSC deposits, e.g., Hayes et al, 2015).

Upper Copper Zone Mining Methods
The UCZ is a flat dipping deposit with multiple parallel lenses. It will be entirely extracted using DF mining methods.

The DF panels will be setup with two parallel access drifts spaced 60 - 90 m apart where possible. Primary ore drifts spaced 15 m apart will be developed from one access drift to within 5 m of the second access drift. Once the drift has completed mining, all the services will be stripped from the drift and a barricade will be built at the access. Paste and breather holes will then be drilled from the second access drift through the pillar and paste fill will be placed in the drift.

Once two adjacent primary drifts have cured, a secondary ore drift will be driven to the end of the panel in the middle of the two cured drifts. This drift will be 5 m wide with two 2.5 m wide pillars on either side. These pillars will then be extracted by drilling unsupported slashes up against the paste and mucking out on remote control. Once the secondary drift has been mined out, a barricade will be built, and the secondary drift will be filled using the same process as the primary drifts.

Once an entire panel has been mined out and both access drifts are paste filled, the pillar is mined out and then paste filled.

In areas where there is no second access to fill from, the same general sequence will be followed. However, the primary drifts will be located 10 m apart and the secondary drifts will be driven at a 5 m width, fully extracting the pillars between the primary drifts with no unsupported slashing. This is to allow the proper tight filling of the secondaries.

Lower Copper Zone Mining Method
The CF mining method has been selected for the LCZ mining area. Due to orebody geometry dipping slightly steeper than the UCZ and no parallel lenses, multiple lifts will be taken from a single attack access. The attack access will be driven from the LCZ access. In this method, extraction will commence from the lowest lift and progress up vertically. In each lift, primary CF production drifts will be extracted and then filled with paste. After the primary CF production drifts have been backfilled, mining of secondary drifts will commence. The secondary production drifts and stopes will also be backfilled using paste fill.

Once all the secondary drifts on a lift have been extracted the access will be backslashed and the lift above will be extracted. The sequence will be strictly bottom-up except for a few locations where sill pillars have been selected to increase production from the LCZ.

Mine Design
The Johnny Lee deposit will be accessed by a single Main Decline driven from surface. The decline dimensions will be 5 m wide by 5 m high and excavated with a flat back to maximize the stability of the flat dipping joint sets that are prevalent throughout the Project.

The decline will be excavated at a maximum gradient of -15% from the surface and pass to the east of the UCZ. A single access drift will be driven from the decline into the UCZ. From this access drift an initial ventilation connection and second means of egress to surface will be established. This access drift will serve as a take-off point for access drifts for mining the UCZ panels.

The decline will continue to spiral below the UCZ connecting to the return air and secondary egress system which will be advanced in raises until the access is in the HW of the VVFZ. Due to poor expected ground conditions in this area, rather than driving raises, two parallel drifts, one acting as the Main Decline and the second acting as the return airway and secondary egress, will be driven through the VVFZ to access the LCZ.

The LCZ zone is made up of two pods both of which will be accessed from a decline driven in the FW of the pods. Attack drifts will be driven off the decline at regular intervals to access the ore.

All vertical development will be performed by a contractor. Development of the Main Decline as well as the UG infrastructure will also be performed by a contractor while the ore production will primarily be performed by the owner.

All UG production openings will be backfilled with cemented paste backfill. Paste backfill will be required to provide a working floor for some areas as well as to support the back and allow for complete extraction of the ore with no pillars remaining in-situ.

Once the LCZ has been accessed the owner will shift a portion of their fleet to the LCZ and commence stoping in the LCZ. Stoping will continue in both areas until they are depleted. The overall mine life from commencing development of the decline is just over nine years. Production mining is currently at eight years

Crushing
The crushing circuit was designed by Orway Mineral Consultants (OMC)(Borger and Kock, 2019), based on an Impact Crush Work index (CWi) of 10.7 kWh/t. A single stage crushing circuit has been selected to complement the selection of a SAG mill as the primary grinding method.

UG ore will be delivered to the Run Of Mine (ROM) pad and stored in a number of separate stockpile fingers according to ore type and grade to facilitate blending. Stockpiled material will be reclaimed by a FEL for direct feed to the crushing plant ROM bin.

Ore will be withdrawn from the 90 t capacity ROM bin using a variable speed apron feeder which will discharge onto a 1.12 m wide by 6.16 m vibrating grizzly with 64 mm bar spacing. Based on the selected ROM size distribution, 67% of the ROM feed will report to the jaw crusher, while the grizzly undersize will bypass the crusher via a chute directly onto the crushed ore conveyor. A single toggle jaw crusher (CJ411) has been selected for the crushing duty. The jaw crusher Closed Side Setting (CSS) will be maintained at 100 mm to achieve a crushed product size P80 of 99 mm. Crushed rock will be conveyed to a Coarse Ore Bin (COB) of 2,500 t capacity that will provide 16.7 hours of surge.

Grinding
A two stage, SAG and ball mill grinding circuit has been selected to achieve the target grind size P80 of 38 µm to the flotation circuit. The mill selection has been based on the OMC simulation and an SMC specific energy calculation to determine the grinding power requirements and mill sizes.

Fresh ore will be reclaimed from the COB by two variable speed feeders and discharged onto the fixed speed mill feed conveyor. The primary SAG mill, with dimensions 6.10 m Ø x 3.05 m Effective Grinding Length (EGL), will be equipped with a 2,000 kW variable speed mill motor. A grate discharge system using 25 mm grates has been selected in combination with a discharge trommel at 12 mm apertures. Oversize from the SAG mill trommel will be conveyed to a pebble crusher for size reduction of the pebbles prior to returning to the mill feed conveyor. Trommel undersize pulp will be pumped to a primary sizing screen fitted with 2 mm polyurethane screen panels; screen oversize will be treated in closed circuit with the SAG mill while undersize material will gravitate to the ball mill discharge sump. The nominal SAG mill transfer size (T80) to the secondary ball mill will be 600 µm and controlled by the primary sizing screen.

The secondary ball mill will be fixed speed grate discharge mill (5.50 m Ø x 8.10 m EGL), operating at 75% of critical speed with a design ball charge of 27%. A grate discharge system using 15 mm grates will provide slurry flow to the mill trommel screen, fitted with 10 mm aperture panels. The trommel screen is required to remove ball scats only.

The OMC simulations highlighted the importance of minimizing the SAG mill transfer top size to the secondary ball mill. Consequently, to optimize grinding efficiency, a vibrating screen has been installed to classify the SAG mill discharge product with a sizing screen fitted with 2 mm screen decks, and to control the transfer size to the ball mill circuit to 600 µm.

The secondary ball mill will operate in closed circuit with a cluster of 250 mm diameter cyclones. The cyclones have been designed with a circulating load of 250% and will have an overflow pulp density of 35% solids to achieve the flotation feed size P80 of 38 µm. The cyclone overflow will report to a horizontal, vibrating trash screen 1.5 m wide by 4.8 m long. The trash screen will be fitted with polyurethane screen panels having an aperture of 1.0 mm. Cyclone underflow will be directed to the ball mill feed chute.

Trash screen oversize will gravitate directly to a trash bin. Undersize from the trash screen will gravitate to the Cu flotation feed conditioning tank. A launder sampler will be located on the trash screen underflow and the sample will be pumped to the On-Stream Analyzer (OSA) for elemental and density analysis.

The selected process recovery method will utilize industry standard comminution and flotation process technologies to produce a copper sulphide concentrate for market export. The design processing rate of 150 dry tph will provide for the annualized 1.2 Mtpa treatment of UG sulphide mineralization, producing 122 ktpa of copper sulphide concentrate. The process plant will operate on a continuous 24 hour-a-day basis, via two 12 hour processing shifts. The design availability of the crushing and grinding circuits will be 70% and 92%, respectively.

Cu Flotation Circuit
The Cu minerals, chalcopyrite and tennantite, will be recovered from the pyrite and non-sulphide gangue throughout the Cu flotation circuit at an elevated pulp pH of 9.5. Lime will be used to maintain the flotation circuit pH conditions. Aero 3477 will be the main copper sulphide collector and will be added in a stage-wise manner to avoid overdosing, which may result in the inadvertent recovery of the pyrite ( ........