Ms. Joanne Freeze reports

ALTA COPPER ANNOUNCES ROBUST ECONOMICS FOR CANARIACO WITH US$2.3 BILLION AFTER-TAX NPV AND 24% IRR

Alta Copper Corp. has released attractive economics results from the 2024 optimized preliminary economic assessment (2024 PEA) at its 100-per-cent-owned Canariaco project, a world-class porphyry copper project, located 700 kilometres northwest of Lima. The 2024 PEA has been prepared by Ausenco Engineering Canada ULC, AGP Mining Consultants Inc. and Whittle Consulting Pty. Ltd., respectively, leading international engineering and mining consultancy firms.

All values contained in this press release are reported in U.S. dollars.

Canariaco 2024 PEA highlights:

• Robust economics: Canariaco 2024 PEA using 8-per-cent discount factor and three-year trailing average metal prices of $4/pound (lb) copper (Cu), $1,850/ounce (oz) gold (Au) and $23/ounce (oz) silver (Ag):
  • Base-case pretax net present value (NPV8) of $4.1-billion and internal rate of return of 32.4 per cent;
  • Base-case after-tax NPV8 of $2.3-billion and IRR of 24.1 per cent;
  • Significant upside to higher metal prices -- at $4.50/lb Cu after-tax NPV8 of $3.2-billion and IRR of 28.9 per cent;
  • Highly leveraged to copper price: For every 25 cents/lb Cu increase above $4 Cu approximately $425-million is added to the after-tax NPV8 life-of mine (LOM) metal production of 8,026 Mlb (3,642 million tonnes) Cu, 1.67 million oz Au and 33.2 million oz Ag.
• Average annual metal production (year 1 to 10) of 347 Mlb (158,000 tonnes) Cu; 70,000 oz Au; 1.5 million oz Ag;
• Average annual metal production LOM of 294 Mlb (134,000 tonnes) Cu; 61,000 oz Au; 1.2 million oz Ag;
• After-tax average annual free cash flow (year 1 to 10) from start of operation: $538-million;
• After-tax average annual free cash flow LOM from start of operation: $383-million;
• C-1 cost of $1.86/lb copper (net of byproducts);
• Total average operating cost of $11.21 per tonne processed;
• All-in sustaining costs (AISC) of $1.96/lb copper;
• Preproduction capital cost of $2.2-billion based on leased mining equipment and including a contingency allocation of 21 per cent on initial project capital;
• Rapid after-tax payback period of 3.1 years from initial production with a 27-year mine life;
• One of the lowest capital intensities when compared with other current global copper development projects.

The 2024 PEA is preliminary in nature. Current published resources for both of the Canariaco Norte and Canariaco Sur deposits (previously reported in news release dated Jan. 28, 2022) include inferred mineral resources along with a significant percentage of measured and indicated resources. Inferred mineral resources are considered too speculative geologically to have economic considerations applied to them that would enable them to be categorized as mineral reserves and there is no certainty that the 2024 PEA will be realized. Mineral resources that are not mineral reserves have not demonstrated economic viability.

An independent technical report for the 2024 PEA, prepared in accordance with National Instrument 43-101, will be available under the company's SEDAR+ profile and website on or before June 7, 2024.

For readers to fully understand the information in this news release, they should read the technical report in its entirety when it is available, including all qualifications, assumptions, exclusions and risks. The technical report is intended to be read in its entirety and sections should not be read or relied upon out of context.

An updated corporate presentation will be available on the company's website.

Giulio T. Bonifacio, executive chair, commented: "We are extremely pleased with our 2024 PEA which is well advanced as we have clearly benefited from several previous engineering studies and a wealth of experience from our external international engineering firms. This PEA will prove of great value as we advance Alta Copper to the next stage. The PEA shows that Canariaco is clearly a Tier 1 asset that provides a long-life, large-scale copper project producing annual average copper of 158,000 tonnes per year in the first 10 years. The Canariaco project is economically robust with considerable leverage to increasing copper prices while also possessing considerable upside through resource expansion drilling with numerous high-priority drill targets identified to date at Norte, Sur and the undrilled Quebrada Verde porphyry target."

NPV sensitivities

The sensitivity analysis provides a range of outcomes for the project when the key parameters vary from their base case values. The NPV estimate is most sensitive to changes of metal prices, resource grade, overall operating costs and capital costs.

The after-tax NPV ranges from $2,054-million to $4,011-million as the applied copper price varies from $3.85/lb Cu to $5/lb Cu.

Project description

The Canariaco project is situated within the province of Ferrenafe, in the department of Lambayeque, in northwestern Peru, approximately 700 km northwest of Lima, the capital of Peru, and approximately 102 km northeast of the city of Chiclayo. Current access from Chiclayo to the Canariaco project is 150 km along a paved road followed by secondary gravel roads.

The project area covers moderate elevations ranging from 2,200 to 3,600 metres above sea level. The copper deposits are situated on the eastern side of the continental divide and infrastructure will be on the top as well as both western and eastern sides of the divide. The topography varies from steep incised valleys at lower elevations to open grassy highlands at upper elevations. There is sufficient suitable land available within the concessions and close to the mining areas for the process plant, ancillary infrastructure, and comingled waste rock and dry stack tailings facility.

The 2024 PEA contemplates that Canariaco would be mined using conventional open-pit mining equipment followed by crushing, semi-autogenous grinding/ball mill grinding, and flotation recovery of copper, gold and silver to a copper concentrate.

Canariaco is estimated to have relatively low project capital and operating costs due to proximity to infrastructure and favourable natural setting with key features as follows:

• Large-scale mining and processing operation to process 120,000 tonnes per day/43.8 million tonnes per annum with a currently planned 27-year mine life;
• Conventional drill and blast mining, large-scale electric shovels and haul trucks;
• Conventional crushing, SAG and ball mill grinding followed by flotation recovery of copper, gold and silver to a copper concentrate;
• Application of best practice process tailings management through comingled waste rock and filtered dry stack tailings storage;
• Water resources available in project area exceed project requirements;
• Low strip ratio life of mine of 1.33:1;
• Power supply from existing northern Peru power grid with connection point only 57 km from the project;
• Project site located only 24 km from existing paved highway connecting to the Pan American Highway on the west coast.

Low capital cost intensity

Importantly, the Canariaco project has low capital intensity when compared with several other global copper projects currently in the development stage. Key project attributes that reduce the capital cost include the following:

• The mineralized material from Canariaco Norte and Sur deposits are moderately competent with Axb of 53, and moderately soft rock with an average BWI 12.2 kilowatt-hours/tonne, which enables high throughput utilizing a single comminution line consisting of one primary crusher, one large SAG mill and two ball mills whereas many projects with comparable throughput require two SAG mills and four ball mills.
• The region receives significant annual rainfall and adequate freshwater is available at site, eliminating the need for a desalination plant and pipeline from the coast.
• Relatively close proximity to the national power grid reduces the capital intensity of power supply infrastructure.
• Close proximity to an existing major transportation highway reduces access road construction cost and time.
• Utilization of trucks to transport concentrate along existing highways to the loadout port eliminates the requirement for a concentrate pipeline.
• The project site is in a sparsely populated area and there is no requirement for community relocation.
• Concentrate loadout through an existing port on the west coast of Peru eliminates need to construct a new loadout facility.

Sustainable and responsible mining

The project development concept has utilized best practice technologies and will benefit from several existing external factors which will assist in making Canariaco a very responsible, desirable and sustainable project.

The application of filtered dry stack tailings combined with comingled waste rock storage maximizes the recycling of process water and significantly reduces freshwater requirements. In addition, this technology eliminates the need for wet tailings storage and a major tailing retainment structure and reduces associated seismic risk.

Electrical power in northern Peru is generated predominantly by hydro which is the preferred power source from ecological and carbon emissions perspectives.

Electric-powered overland belt conveyors, rather than haul trucks, will transport most of the mill feed and waste rock from the mining areas to the plant as well as the comingled waste and dry stack tailings facility, thereby reducing fuel consumption and carbon dioxide emissions.

The project is located in a sparsely populated region and at elevations above major agricultural zones.

Capital, sustaining and operating costs

The initial capital, expensed over the first four years of the project, amounts to $2.2-billion. The sustaining capital over the remainder of LOM amounts to $526-million. Closure costs are estimated at $216-million. The project financial model incorporates a lease strategy for the purchase of the initial mining equipment whereby 20 per cent of the mining fleet cost is capitalized and the remainder is carried as operating cost. Sustaining costs include construction of a crusher at the Sur deposit and related conveyor system to connect with the primary overland conveyor in year 16 prior to the start of mining operations at Sur.

Social and environmental

Alta Copper has been active in the Canariaco area since 2004 and since that time has developed and established a wide range of relationships with a corporate policy of respect, shared involvement and value, mutual benefit, and transparency. Communications with the local communities and public authorities at all levels continue to ensure that key stakeholders are aware of the Canariaco project status and plans, and that the company responds to community concerns and requests.

Mining

The 2024 PEA is based on open-pit mining methods with conventional drilling, blasting and material loading with large electric shovels for excavation and haulage to the primary crusher using large capacity haul trucks. Independent and dedicated high-capacity electric conveyor systems will transport plant feed from the primary crusher to the process plant and waste to the comingled waste and dry stack tailings facility.

Over the life of the Canariaco mine, two separate deposits, Canariaco Norte and Canariaco Sur, will be mined in separate pits, with the bulk of the plant feed coming from Norte. Mining will commence in the Norte pit which will provide 100 per cent of the process plant feed until year 16 at which point mining operations will commence at Sur. Years 17 through 25 will see mining taking place in both Norte and Sur with variable mining rates while maintaining total annual production of 43.8 million tonnes. From year 26 through end of mine life all mining will take place in Sur.

The Canariaco open-pit mining operations will have a mine life of 27 years, operating 365 days a year with a life-of-mine strip ratio of 1.33:1 (including prestripping). The mine production plan is based on mining a total of 2.72 billion tonnes of material, comprising 1,176 million tonnes of plant feed and 1,548 million tonnes of waste rock over the life of the mine. Mining operations will supply the process plant at 120,000 tonnes per day or 43.8 million tonnes per annum. During the life-of-mine operation, annual cash flow will vary due to annual and forecast variations in head grade, strip ratio and metal recoveries.

The major mining equipment fleet will include nine blast hole drills, five 38-cubic-metre electric shovels, two 33-cubic-metre front-end loaders and 38 290-tonne capacity haul trucks. A fleet of smaller loaders and trucks will be utilized for early mine access development and initial prestripping. Electric shovel major maintenance and mobile equipment replacement are carried in the mining costs. The moderate altitude of the project avoids the need for derating of mine haul truck drive systems.

Whittle Consulting's mine plan optimization

A key part of the mining plan development for this 2024 PEA included comprehensive mine plan optimization analysis by Whittle. This analysis includes a very detailed assessment of metal grades, metal prices, metal recoveries, mining and processing costs throughout the deposit, and by applying advanced computational analysis, including by the use of Whittle's proprietary Prober-E software, develops an optimized mining plan to maximize the net economic value of the mining operation. A key aspect of this mine planning strategy is that it brings forward cash flow and optimizes the net present value of the deposit. This approach involves advanced pit phasing techniques and takes advantage of variable mining cut-off grades, plant feed stockpiling and blending strategies during the life-of-mine plan.

Metallurgy and processing

The Canariaco project comprises two copper-gold-silver porphyry deposits where the main copper species are primarily sulphides, predominantly chalcopyrite with lesser amounts of bornite and chalcocite. The Sur deposit also contains molybdenum; however, the levels did not warrant recovery for this 2024 PEA. Extensive metallurgical test work programs on samples from Norte have been completed over previous years, providing an extensive metallurgical database for Norte. Resource development at Sur is at a much earlier stage than Norte and accordingly the metallurgical test work completed for Sur is preliminary. However, the test work results received to date from Sur are very good and comparable with the results for Norte confirming the amenability of conventional flotation recovery for both Norte and Sur.

The key metallurgical design parameters applied for process design in the 2024 PEA are as follows:

• Mineralized material competency/hardness -- drop weight test parameter Axb 53 (75th percentile), bond ball mill work index 12.2 kWh/tonne (75th percentile), moderately competent and moderately soft;
• Grind size P80 for flotation feed: 200 microns;
• Metallurgical recoveries (life of mine) -- copper: 88.2 per cent, gold: 63 per cent, silver: 53 per cent;
• Copper concentrate --copper: 26 per cent, gold: 3.7 grams per tonne, silver: 74 g/t.

Mine haul trucks will transport plant feed material to the crushing station where they will dump the material directly into a large gyratory crusher. From the crusher, plant feed material will be conveyed to a live stockpile ahead of the grinding circuit. Plant feed will be drawn from the stockpile and fed to a single 12.8 m diameter by 8.2 m EGL (effective grinding length) SAG mill. SAG mill discharge will be screened to remove oversize pebbles which will be crushed in pebble crushers and returned to the SAG mill feed. SAG mill screen undersize product will be fed to two parallel 8.5 m diameter by 11.4 m EGL ball mills operating in closed circuit with cyclones to produce floatation feed at 80 per cent minus 200 microns. The floatation circuit will comprise rougher and cleaner flotation stages, with rougher concentrate regrinding prior to cleaner flotation. Cleaner concentrate will be dewatered using a thickener and pressure filters, then conveyed to the concentrate storage building to await transportation to the port for loadout and shipping to offshore smelters.

Waste and tailings handling

The Canariaco process flowsheet has included comingled dry stack tailing technology for waste rock and tailings placement. This technology is considered as best practice and is seeing more application within the global mining industry. The technology offers three key benefits:

• Increases process water reclaim and recycling;
• Eliminates the requirement for wet tailings containment dams and eliminates related seismic risk;
• Reduces the size of tailing containment system footprint. Dry stack tailings treatment utilizes pressure filters to dewater process tailings to low moisture content with recovered water recycled to the process. The dry tailings filter cake produced are transported by belt conveyor to the tailings management facility where they can be placed or stacked with waste rock as a stable pile within the tailings facility. Combining the dry tailings sands with waste rock within the same pile enhances the overall stability of the pile and eliminates the need for two separate facilities.

Qualified persons and NI 43-101 technical report

The 2024 PEA summarized here for the Canariaco project was completed by Ausenco Engineering Canada of Vancouver, B.C., with mining aspects completed by AGP Mining Consultants.

The findings of the 2024 PEA will be disclosed in an NI 43-101 technical report which will be completed and available on SEDAR+ and Alta Copper's website on or before June 7, 2024.

The qualified persons for the 2024 PEA and this news release are identified below:

Gordon Zurowski, PEng, principal mining engineer at AGP Mining Consultants and an independent qualified person as set forth by NI 43-101, is responsible for mine design and mine capital and operating costs. Mr. Zurowski has reviewed the news release against the technical report.

Kevin Murray, PEng, principal process engineer at Ausenco Engineering Canada and an independent qualified person as set forth by NI 43-101, is responsible for the financial model as well as mineral processing and metallurgical resting, recovery methods, and process and infrastructure capital and operating costs. Mr. Murray has reviewed the news release against the technical report.

Scott Elfen, PE, global lead geotechnical and civil services at Ausenco Engineering Canada and an independent qualified person as set forth by NI 43-101, is responsible for the waste management facility and associated capital and operating costs, and the site-wide water management design. Mr. Elfen has reviewed the news release against the technical report.

James Millard, PGeo, director, strategic projects, at Ausenco Sustainability and an independent qualified person as set forth by NI 43-101, is responsible for environmental studies, permitting, and social and community impacts. Mr. Millard has reviewed the news release against the technical report.

Joanne Freeze, PGeo, president, chief executive officer and director, has reviewed and approved the contents of this release for Alta Copper.

About Alta Copper Corp.

Alta Copper is focused on the development of its 100-per-cent-owned Canariaco advanced-staged copper project. Canariaco comprises 97 square km of highly prospective land located 102 km northeast of the city of Chiclayo, Peru, which includes the advanced-stage Canariaco Norte deposit, Canariaco Sur deposit and Quebrada Verde prospect, all within a four km northeast-southwest trend in northern Peru's prolific mining district. Canariaco is one of the largest copper deposits in the Americas not held by a major.

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