Summary

Deposit type

• Porphyry

Summary:

The bulk of the known copper mineralization at Copper Mountain occurs in a northwesterly trending belt of Nicola Group rocks, approximately 5 km long and 2 km wide, that is bounded on the south by the CMS and on the west by the northerly trending Boundary Fault system.

Deposit Types
The Copper Mountain deposit is considered to be an example of an alkalic porphyry deposit. Although less common globally than calc-alkalic porphyry deposits, alkalic porphyry deposits are common in B.C. where they have been extensively studied.

Mineralization
The bulk of the known copper mineralization at Copper Mountain occurs in a northwesterly trending belt of Nicola Group rocks, approximately 5 km long and 2 km wide, that is bounded in the south by the CMS and in the west side by the northerly trending Boundary Fault system. Here copper mineralization occurs as structurally controlled, multidirectional veins and vein stockworks, with peripheral disseminations. Mineralization has been subdivided into four types, as follows:
• Disseminated and stockwork chalcopyrite, bornite, chalcocite, and pyrite in altered Nicola Group volcanic rocks and LHIC rocks that formed much of the core of the deposit in the southern part of the CM Main Pit
• Bornite-chalcopyrite associated with pegmatite-like veins (coarse masses of orthoclase, calcite, and biotite situated along the northern contact of the CMS within the Nicola Group
• Magnetite–(±hematite)–chalcopyrite replacements and/or veins) mineralogically similar to the chalcopyrite–pyrite-bearing pegmatite-textured veins, but carry significantly higher gold grades (Stanley and Lang, 1993) relative to other mineralized zones
• Chalcopyrite-bearing magnetite breccias (Fahrni et al., 1976; Holbek et al., 2020; Preto, 1972; Stanley et al., 1995) within the Ingerbelle Pit and the north side of the CM Main Pit mineralized with chalcopyrite and pyrite and are bounded by a higher-grade zone of copper– gold mineralization.

Weathering
Due to recent glaciation, most of the Copper Mountain deposit is characterized by a relatively fresh erosion surface, with limited surficial oxidation and no significant secondary enrichment of copper. Locally, the overlying Princeton Group has preserved a thin layer of oxidized mineralization and small supergene zones below the basal unconformity of the Princeton Group rocks. Fahrni et al. (1976) state that primary sulphide mineralization extends to the present surface, and oxidation is limited to the upper 15 m of fault and fracture zones. Recent mining in the North Pit area has exposed an irregular zone of supergene weathering extending about two benches from the surface.

Alteration
Alteration types in the Copper Mountain deposit are typical of porphyry copper deposits. Three major alteration assemblages are observed at CM: potassic, sodic, and propylitic. Other volumetrically minor alteration types include kaolinitic and sericite-chlorite clay (Stanley et al., 1995).

Contact metamorphism from the CMS resulted in pervasive hornfelsing of the Nicola Group volcanic rocks within a northwest-oriented zone between the CMS and the LHIC, near to CMS and LHIC dykes (Preto, 1972). Biotite and calc-silicate hornfels preceded all hydrothermal alteration and subsequent copper mineralization at Copper Mountain (Stanley et al., 1995).

Sodic alteration at Copper Mountain is observed as albite, with lesser amounts of diopside, epidote, and locally scapolite. Fracture-controlled sodic alteration in the Copper Mountain main zone is conspicuous within the intrusive breccia (INBX) and Nicola Group volcanic rocks. Sodic alteration is texturally destructive, replacing almost all existing minerals with very fine-grained to aphanitic albite with minor diopside and spots or patches of epidote (Holbek et al., 2020).

Potassic alteration at Copper Mountain can be observed within intrusive rocks and volcanicsedimentary units; however, it is best developed within intrusive dykes of the LHIC. Potassic alteration occurs as veins, envelopes, and fracture fill, and where strongest appears as pervasive alteration of the entire rock. Potassic alteration crosscuts sodic alteration (Holbek et al., 2020).

Propylitic alteration is characterized by a chlorite–actinolite–calcite-pyrite ± epidote assemblage. It occurs throughout the deposit area, can be locally pervasive, and is best developed outboard of the mineralized areas.

Late calcite veinlets are ubiquitous at Copper Mountain, distinct from calcite-sulphide veins associated with late-stage mineralization, and crosscut all other alteration and mineralization types.

Pervasive kaolinitic alteration and sericite–chlorite–clay alteration are volumetrically minor compared to the other alteration types within the Copper Mountain deposit. Kaolinitic alteration is commonly associated with major structures throughout the deposit and appears to postdate copper mineralization (Holbek et al., 2020; Stanley et al., 1995).

Mining Methods

• Truck & Shovel / Loader

Summary:

Mining at the Copper Mountain Mine(CMM) is by conventional open pit methods. The major components of this mining method are blasthole drilling, blasting, loading, and hauling.

Mining at the CMM consists of two areas: the Copper Mountain Pits (currently in operation) and New Ingerbelle. There is also a low-grade stockpile that will be reclaimed during the mine life.

As of 2024, mineral reserve estimates continued to support a mine life until 2043, with significant upside potential for future resource conversion and mine life extension beyond 19 years.

In 2025, efforts will be focused on continuing the optimization of the operation and advancing the permitting process for the New Ingerbelle expansion. Mining activities will continue to execute the three-year accelerated stripping program intended to bring higher-grade ore into the mine plan.

New Ingerbelle Development
The proposed New Ingerbelle development plan involves renewing mining activities in the historical Ingerbelle open pit on the west side of the Similkameen River. The reserves from New Ingerbelle will be processed in the existing milling facility at Copper Mountain and the tailings generated from processing will also be stored at the existing TMF on the Copper Mountain side of the Similkameen River.

New Ingerbelle Mining Development Plan
The New Ingerbelle Open Pit Push-Back and Mine Life Extension (New Ingerbelle Project) development plan includes several key components:
• A three-phase push-back of the historical Ingerbelle Pit
• Constructing two Waste Rock Facilities (to the north and the south of the proposed pit) to accommodate all waste generated from the New Ingerbelle Pit, and a low-grade stockpile to the south of the New Ingerbelle Pit to facilitate a variable cut-off grade strategy
• Developing haul-road access connecting the New Ingerbelle Pit to the WRFs
• Installing a clear-span bridge over the Similkameen River connecting the Copper Mountain and New Ingerbelle haul roads
• Developing haul-road access connecting the Copper Mountain and Ingerbelle sides of the river to allow for ore haulage from New Ingerbelle to the existing mill.

The haul road connecting the bridge to the Copper Mountain milling facility on the east side of the river (mentioned above) will be cut from the original topography and is designed to be approximately 2.5 km long at a 10% grade. This road (the east haul road) will be trolley capable, presenting an opportunity for future study. It is projected that the excavation of the east haul road will be undertaken by a contractor and is reflected in the capital estimate.

The New Ingerbelle Pit will be mined using the planned fleet at Copper Mountain, and no additional equipment will be required for its development. Equipment and personnel will access the New Ingerbelle Pit via Copper Mountain, and mine operations will continue to be directed from the Copper Mountain side of the Similkameen River.

There are no plans for fixed maintenance services on the west side of the Similkameen River. Shop maintenance will continue to be conducted at the existing Copper Mountain truck shop on the east side of the Similkameen River. The mobile maintenance group will continue to attend to service needs of the New Ingerbelle mining fleet in the field as is currently the case at Copper Mountain.

Production Schedule
Lif-of-Mine Production Scheduling Criteria
The mining schedule is based on operating 24 h/d, 365 d/a. The mine operations and mine maintenance departments’ shift schedules are planned to continue to be two 12 h shifts per day, using four alternating crews. This schedule is quite common and acceptable in Canada. Mining rate varies through the mine life depending on waste stripping requirements and haulage distances. The peak mining rate occurs in 2025 and gradually decreases as waste-stripping demand declines.

Advanced Waste Stripping
From 2024 though 2026, additional waste stripping will take place to address a backlog of waste mining and increase the exposure of high- grade reserves. It is projected that the Copper Mountain fleet and personnel will be accountable for 94 Mt/a of total material movement during this period, and a contractor miner will be responsible for the remainder of the projected material movement. Between the second half of 2024 and mid-2026, the contractor will be responsible for moving 10 Mt in 2024, 20 Mt in 2025, and 10 Mt in 2026.

Comminution

Crushers and Mills

Summary:

Crushing Circuit
Run-of-mine (ROM) is direct-dumped into the primary gyratory crusher at a nominal rate of 2,343 t/h. The primary crushed mineralization is transported from the primary crusher surge pocket up a 1,800 mm-wide variable-speed conveyor where it can be directed either to the SAG-feed stockpile or the secondary crusher-feed surge pile. The feed reporting to the secondary surge pile is reclaimed via two vibratory feeders at a nominal rate of 2,343 t/h via a variable-speed conveyor and is fed to the secondary crusher scalping screen.

The secondary crusher scalping screen is a double-deck screen with a bottom-deck aperture size of 38 mm. All feed passing through the bottom-deck aperture reports to the secondary crushing-product conveyor belt, with all oversize feed reporting via gravity to the secondary crusher. The secondary crusher is configured with a short-head liner package and operates with a variable closed-side setting (CSS) based on the downstream SAG-feed stockpile level. The secondary crusher product combines with the screen undersize and is conveyed to the SAG-feed stockpile.

The fine-ore stockpile has a single reclaim chamber, a live capacity of 20,000 tonnes, and a total capacity of more than 300,000 tonnes when pulled out with mobile equipment. Reclamation of the mineralization from the stockpile is accomplished using three reclaim feeders, with each feeder fitted with a real-time sizing camera. The draw rate from each feeder is variable and is controlled to maintain a constant feed-rate and particle size to the SAG mill.

Major equipment in the grinding and classification area will include:
• Metso Superior MKII Primary Gyratory Crusher, 60 inch by 89 inch, installed power 600 kW
• FLSmidth Raptor XL2000 Secondary Cone Crusher, installed power 1800 kW.

Grinding and Classification
Ore reclaimed from the SAG-feed stockpile is fed to a single variable-speed primary SAG mill operating in closed circuit with a single-duty pebble crusher. The nominal fresh-feed rate to the SAG mill is 2,038 t/h, with a variable pebble recycle-rate of 5% to 10% depending on the feed-ore size. The SAG mill total load is maintained at 24% to 26%, including an 18% ball charge. The SAG discharge is screened via a single-duty, single-deck vibratory screen with 15 mm apertures. The screen oversize reports to the pebble-crushing circuit while the screen undersize reports to the SAG transfer-pump box.

The SAG-mill discharge-screen undersize is pumped from the SAG transfer-pump box to a splitter box, where the slurry is distributed to the three ball mill circuits. Each of the ball mill circuits is fitted with a variable-speed drive and operates in closed circuit, with a dedicated cyclone pack per ball mill. Each ball mill circuit operates with a nominal 300% recirculating load, with the cyclone overflow gravitating to the head of the flotation circuit, and the cyclone underflow gravitating to the ball mill feed-chute. The ball mill circuits produce a flotation feed at a nominal P80 150 µm.

Major Equipment in the grinding and classification area will include:
• One SAG mill, 34 ft in diameter by 20 ft effective grinding length (EGL), installed power 13,560 kW
• Two ball mills, 24 ft in diameter by 39.5 ft EGL, installed power 13,560 kW
• One ball mill, 22 ft in diameter by 28 ft EGL, installed power 12,500 kW
• SAG transfer pumps (1 duty, 1 standby), installed power
• Cyclone feed pumps (1 duty, 1 standby), installed power
• Pebble crusher, FLS XL900 Raptor, installed power 675 kW.

Processing

• Crush & Screen plant
• Column flotation
• Flotation
• Dewatering
• Filter press

Summary:

The processing plant consists of a standard crush–grind–flotation circuit that operates two 12-hour shifts per day, 365 d/a, with targeted plant availability of 92%. The process plant has an installed capacity of 45 kt/d via a comminution circuit consisting of a primary and secondary crushing circuit reducing the feed down to minus 40 mm ahead of a semi-autogenous grinding (SAG) mill, ball mill, and pebble crusher grinding circuit further reducing the feed size to P80 150 µm.

The comminution circuit is followed by a sulphide flotation circuit that produces a copper–silver–gold concentrate. The unthickened flotation tailings are transported via a gravity pipeline to the TMF, with the sands and slime separation occurring on the TMF’s dam walls via mobile cyclone units. The concentrate is dewatered via two pressure filters and stored on site before transport via truck to the Port of Vancouver for shipment to the final customers.

As of 2024, the processing facility had a throughput capacity of 45,000 tonnes per day. Several mill initiatives were implemented in 2024, including, recovery improvements, reprogramming the mill expert system, installation of advanced semi-autogenous grinding control instrumentation, redesigned SAG liner package and updated operational procedures intended to remove magnetite from the pebble stream.

In January 2025, the feasibility engineering was completed to debottleneck the mill through a conversion of the third ball mill to a second SAG mill. The SAG mill conversion project is expected to increase the nominal plant capacity to its permitted capacity of 50,000 tonnes per day earlier than contemplated in the most recent Copper Mountain mine technical report. The mill throughput is anticipated to move towards 50,000 tonnes per day in 2026. Maintenance practices to improve mill availability continue to be a key pillar of Hudbay’s stabilization and optimization initiatives post-acquisition.

Process Plant Description
Flotation Circuit
The three cyclone overflow streams gravitate to the flotation-feed splitter box where the mineral collectors and frother are added. The cyclone overflow is split down two rougher trains, each consisting of five OK160 tank cells. The rougher tailings from both trains recombine, and are further processed to recover remaining sulphide minerals via two OK300 tank cells operating as rougher scavengers. The tailings from the rougher scavengers flow via gravity to the tailings dam, and the concentrate combines with the rougher concentrate generated from the two rougher trains and is pumped to the regrind mill.

The combined rougher concentrate is ground in a regrind ball mill to P80 30 µm. The regrind ball mill is operated in closed circuit with cyclones, with the cyclone overflow pumped onwards to the cleaner circuit, and the cyclone underflow reporting to the regrind ball mill. A portion of the cyclone underground is fed to a rougher-cleaner flash flotation-cell where full, liberated, coarse-copper minerals are recovered at final concentrate grade and report to the final concentrate thickener.

The regrind cyclone overflow is pumped to the first cleaner, which consists of three Eriez columns operating in parallel. The first cleaner concentrate gravitates to the second cleaner—three direct flotation reactors (DFR) in series. The second cleaner concentrate is pumped to the final concentrate thickener while the DFR tailings returns to the first cleaner feed. The tailings from the first cleaner are pumped to the cleaner-scavenger bank. The cleaner scavengers consist of five OK70 tank cells. The cleaner-scavenger concentrate is pumped to the regrind ball mill while the cleaner-scavenger tailings are combined with the rougher-scavenger tailings and report to the tailings dam.

Major equipment in the bulk flotation area will include:
• Ten rougher cells, unit model OK160 tank cells
• Two rougher-scavenger cells, unit model OK300 tank cells
• Two first-cleaner columns, 3.7 m (d) x 12 m (h)
• One first-cleaner column, 6 m (d) x 14 m (h)
• Three DFR second cleaners
• Five cleaner-scavenger cells, model OK70 tank cells
• Regrind ball mill, 14 ft in diameter by 28.5 ft EGL, installed power 2687 kW
• One regrind flash-flotation rougher cell, model Skimair 240
• One regrind flash-flotation cleaner cell, model OK5 tank cell.

Copper-Concentrate Dewatering
The copper concentrate produced by the second cleaner and flash flotation cleaner all report to the final concentrate high-rate thickener. The thickener overflow water is reused in the grinding and flotation circuits. The copper-concentrate thickener underflow is pumped to an agitated-concentrate stock tank prior to the filtration process. Two pressure filters are employed to dewater the copper concentrate to < 9% moisture, with the concentrate dropping via gravity directly into the concentrate storage shed. The concentrate is transported from site to the Port of Vancouver via truck.

Major equipment in the copper-concentrate dewatering area will include:
• One copper-concentrate high-rate thickener, 16 m diameter
• One copper-concentrate stock tank
• Two copper-concentrate pressure filters, 1.5 x 1.5 m plates, 60 plates per filter.

Water Supply

Summary:

The existing freshwater system was designed for 850 m3 /h, with a peak flow of 1,200 m3 /h. However, installing several environmental surface-water collection points has offset freshwater demand. The expansion from 45 kt/d to 50 kt/d will require an average freshwater draw of 1,006 m3 /h; however, this will be further offset with surface-water collection points activated with the start of New Ingerbelle mining in 2027. The permitted freshwater draw rate from the Similkameen River allows for 1,515 m3 /h of flow, with additional flexibility during periods with surplus or minimal precipitation.

A new reclaim barge is planned for 2024, which will be capable of delivering 4,417 m3 /h as required by the site-water balance expansion to 50 kt/d. With additional surface-collection water routed to the TMF, these reclaim pumps will supply sufficient additional water to the process water tank to satisfy production.

Existing Water Management Systems
From 2019 to 2022, several contact water-collection pump stations were established and upgraded. These pump stations collect water at historically permitted discharge points and return them either directly to the TMF or to the concentrator for in-process consumption. These constructed and upgraded systems consist of:
• East seepage and WRF contact water collection, pond, and pumping infrastructure
• West dam toe seepage collection, pond, and pumping infrastructure
• Adit 6 discharge pumping infrastructure
• SW38/63 contact water collection and pumping infrastructure
• In-pit dewatering collection and pumping infrastructure.

Additional study work is under way for water capture at the toe of the existing east dam. The intent of this study is to determine the best achievable method for collecting additional sulphates present in dam toe and WRF contact water. Once designed, this system will integrate with the existing east seepage pump-station and be returned to the TMF pond to be reclaimed as process water.

Concentrator process water is recycled from the TMF pond, with additional make-up water pumped from the Similkameen River.

Freshwater supply is composed of two 224 kW and two 335 kW pumps on the west side of the Similkameen River. Fresh water is pumped across the existing Similkameen River pipe bridge to a booster station equipped with three 522 kW pumps for transport to the freshwater storage tank.

Process water is pumped from two 447 kW and two 597 kW vertical turbine pumps (mounted on a barge) to a booster station (consisting of five 597 kW booster pumps) that sends flow to the process water storage tank.

Potable and wastewater treatment facilities servicing the full allotment of operating and administration staff.

One 18-inch-diameter and two 20-inch-diameter pipelines span the Similkameen River on a cable-supported bridge.

Commodity Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Environmental Manager	Colleen Hughes		Apr 8, 2025
Health & Safety Manager	Jeff Zmurchyk		Apr 8, 2025
Mill Maintenance Superintendent	David Keyworth		Apr 8, 2025
Mine Operations Manager	Greg Wolbeck		Apr 8, 2025
Supply Chain Superintendent	Cory Forcier		Apr 8, 2025
VP Operations	John Ritter		Apr 8, 2025