Capstone Announces Mantoverde Optimized Feasibility Study

(All amounts in US$ unless otherwise indicated)

VANCOUVER, British Columbia–(BUSINESS WIRE)–Capstone Copper Corp. (“Capstone” or the “Company”) (TSX:CS) (ASX:CSC) today announced the results of a feasibility study (“FS”) for its Mantoverde Optimized brownfield expansion project (“MV Optimized” or “MV-O”).


John MacKenzie, Capstone’s Chief Executive Officer, commented, “We are excited to release the results of our MV Optimized Feasibility Study which, when combined with our recently released Santo Domingo Feasibility Study, defines the next phase of transformational growth for Capstone. MV Optimized is a capital efficient, high return and low risk expansion project that is expected to bring on an additional 20,000 tonnes per annum of copper for approximately $146 million of capital. We see the MV-SD district producing approximately 250,000 tonnes of copper per annum, placing it amongst the largest producing copper districts in the world, with very attractive unit cash costs. Between MV Optimized and Santo Domingo, we expect to have significant optionality to surface further value, including through exploration drilling which has not been performed at Mantoverde since 2019. Our team is committed to pursuing the highest standards in safety and environmental management as well as continued engagement with all stakeholders as we progress our growth plans. The ramp up of the current Mantoverde Development Project continues to progress well and I am thrilled that the plant achieved commercial production in September.”

MANTOVERDE OPERATION SUMMARY

Mantoverde (70%-owned by Capstone Copper and 30%-owned by Mitsubishi Materials Corporation) is an open-pit copper-gold mine located in the Atacama region of Chile. Since the 1990s, Mantoverde operated as an oxide mine producing copper cathodes from its 60,000 tonnes per annum capacity SX-EW plant. Last year in 2023, Capstone Copper completed construction of the Mantoverde Development Project (“MVDP”) that enabled the mine to process its copper sulphide reserves, in addition to existing oxide reserves. The MVDP involved the addition of a sulphide concentrator (nominal 32,000 ore tonnes per day (“tpd”)) and tailings storage facility, and the expansion of the existing desalination plant and other minor infrastructure. First saleable copper concentrate at MVDP was produced in June 2024 and commercial production was achieved in September 2024. Commercial production is defined as the achievement of reaching a minimum of 30 consecutive days of operations during which the mill operated at an average of 75% of nameplate throughput of 32,000 tpd.

MANTOVERDE OPTIMIZED FEASIBILITY STUDY

MV OPTIMIZED HIGHLIGHTS

  • MV Optimized is a capital efficient debottlenecking expansion of the existing sulphide concentrator from throughput of 32 ktpd to 45 ktpd
  • An extended 25-year mine life is supported by a higher sulphide Mineral Reserve1 estimate of 398 million tonnes at a copper grade of 0.49% and a gold grade of 0.10 grams per tonne

    • Sulphide Mineral Reserve tonnes have increased by 68% while contained copper has increased by 40%
  • The updated oxide Mineral Reserve2 estimate is 236 million tonnes at a soluble copper grade of 0.21%

    • Oxide Mineral Reserve tonnes have increased by 18% while contained copper has increased by 11%
  • Expansionary capital of $146 million yields total incremental production of 368,000 tonnes of copper and 215,000 ounces of gold compared to the previous technical report, reflecting a capital intensity of approximately $7,500 per tonne of incremental annual copper equivalent production
  • Over the next five years, annual production from Mantoverde is expected to average 135,000 tonnes of copper and 37,000 ounces of gold at attractive C1 cash costs of $1.81 per payable pound of copper produced

    • Over the 25-year mine life, production is expected to average 81,000 tonnes of copper and 32,000 ounces of gold at robust C1 cash costs of $2.04 per payable pound of copper produced
  • MV Optimized outlines an after-tax net present value at an 8% discount rate (“NPV8%”) of $2.9 billion for the Mantoverde operation on a 100%-basis based on a $4.10/lb long-term copper price assumption
  • Capstone plans to begin construction of MV Optimized following acceptance of its environmental DIA permit application and subject to Board approvals. The DIA permit application was submitted in H1 2024 and approval is expected in H1 2025
  • The Company plans to progress several value enhancement initiatives within the Mantoverde-Santo Domingo (“MV-SD”) district, noted in the Opportunities section but not yet incorporated into the base case MV Optimized plan, including:

    • Processing of oxide material from Capstone’s neighbouring Santo Domingo and Sierra Norte projects using Mantoverde’s excess SX-EW capacity
    • Recovery of cobalt and additional copper from a pyrite concentrate
    • Ongoing exploration of the MV-SD district, including the recently acquired Sierra Norte deposit

A summary of key production and cost details for MV Optimized can be found below. For further details, please refer to Exhibit 1 at the end of this news release.

______________________________

1 Composed of 219 million tonnes in the Proven category and 179 million tonnes in the Probable category. Please refer to the detailed breakdown of the Mantoverde Mineral Reserve estimate below.

2 Composed of 148 million tonnes in the Proven category and 88 million tonnes in the Probable category. Please refer to the detailed breakdown of the Mantoverde Mineral Reserve estimate below.

 

 

2025-

2029

Avg.

2030-

2034

Avg.

2035-

2039

Avg.

2040-

2044

Avg.

2045-

2049

Avg.

First 10

Years

Avg.

2025-

2049

Total

Production

Contained Copper in Concentrate

tonnes

(000s)

99

90

69

47

32

95

1,684

Copper Cathodes

tonnes

(000s)

36

21

13

28

347

Total Copper

tonnes

(000s)

135

111

82

47

32

123

2,031

Gold in Concentrate

ounces

(000s)

37

43

36

26

19

40

805

C1 Cash Costs3

Sulphides C1 Cash Cost

$ / payable

lb Cu

$1.48

$1.61

$2.42

$2.40

$2.18

$1.54

$1.90

Cathodes C1 Cash Cost

$ / payable

lb Cu

$2.68

$2.74

$2.64

n/a

n/a

$2.70

$2.69

Combined C1 Cash Cost

$ / payable

lb Cu

$1.81

$1.83

$2.46

$2.40

$2.18

$1.82

$2.04

MV OPTIMIZED EXPANSIONARY CAPITAL COST ESTIMATE

The current process infrastructure of the MVDP can sustain up to 45,000 tpd by debottlenecking minor components of the plant. The expansionary capital costs for MV Optimized have been estimated at $146 million as shown in the following table. This reflects a total capital intensity of approximately $7,500 per tonne of incremental annual copper equivalent production.

EXPANSIONARY CAPITAL COST ESTIMATE (by area)

($ millions)

Mine

38

Concentrator processing plant

84

Oxide leach optimization

17

Desalination plant

7

TOTAL EXPANSIONARY CAPITAL COST

146

______________________________

3 C1 cash costs are net of gold by-product credits and selling costs. These are Non-GAAP performance measures; please see “Non-GAAP and Other Performance Measures” at the end of this news release.

Capital for the mine of approximately $38 million reflects the addition of one hydraulic shovel and five haul trucks to support the expanded mining and processing rate of nearly 45,000 tpd, compared to the current nameplate capacity at the Mantoverde Development Project of 32,000 tpd. The strip ratio for MV Optimized has increased to 2.7:1 compared to 2.1:1 for MVDP.

Capital for the processing plant of approximately $84 million reflects additional and/or upgrades to equipment, notably including pipes, pumps, flotation cells, cyclone feed pumps, electrical cabling, and other auxiliary infrastructure to debottleneck the plant.

Capital for the oxide leach optimization of approximately $17 million reflects infrastructure for improved heap and dump management, plus the conversion of the dynamic heap to a bioleach facility to extract sulphide-based copper. The conversion of the dynamic heap to a bioleach facility will also facilitate the potential future extraction of cobalt.

Capital for the desalination plant of approximately $7 million reflects upgrades to ensure a stable flow of the required water for MV Optimized.

For a breakdown of annual capital expenditures, including sustaining and deferred stripping capital, please see Exhibit 1 at the end of this news release.

MINERAL RESERVE ESTIMATE

The Mineral Reserves detailed below consider both oxide and sulphide mineralization as part of the Mantoverde Optimized study. Mantoverde is an open pit-mining complex where oxide ore is treated through both Heap and Dump (ROM) leaching processes and recovered via conventional SX-EW plant to produce copper cathodes. The sulphide ore is processed using a concentrator plant.

The Mineral Reserve was developed by Capstone and contains all Proven and Probable category material planned for processing in MV-O. The designed pit was based on a Lerchs-Grossman optimization process using Whittle software and a detailed phased pit design using the oxide and sulphide pit shells. As a result of the optimization process, six mine phases for oxide material and 15 mine phases for sulphide material were designed to prioritize the higher-grade zones within the mineral extraction plan, while maintaining suitable working widths that would enable high productivity mining sequences using large-scale mining equipment. Mining assumes conventional open pit operations using truck-and-shovel technology.

Following is the current Mineral Reserve Estimate as at June 1, 2024.

Mineral Reserves – Flotation

Category

Tonnage

(Mt)

Grade

Contained Metal

TCu %

Au g/t

Cu (kt)

Au (koz)

Flotation – Sulphide

Proven

181

0.58

0.10

1,044

602

Probable

160

0.41

0.09

656

474

Total

341

0.50

0.10

1,700

1,077

Flotation – Mixed

Proven

38

0.49

0.08

187

99

Probable

19

0.35

0.08

68

47

Total

58

0.44

0.08

255

146

Flotation – Sulphide + Mixed

Proven

219

0.56

0.10

1,231

702

Probable

179

0.40

0.09

723

521

Total Reserves

398

0.49

0.10

1,954

1,223

Mineral Reserves – Leach

Category

Tonnage

(Mt)

Grade

Contained Metal

TCu %

SCu%

Cu (kt)

SCu (kt)

Heap leach – Oxide + Mixed

Proven

76

0.40

0.30

300

226

Probable

37

0.36

0.27

132

101

Total

113

0.38

0.29

432

327

Dump leach – Oxide + Mixed

Proven

72

0.18

0.14

131

99

Probable

51

0.20

0.14

102

69

Total

123

0.19

0.14

233

168

Heap + Dump Leach – Oxide + Mixed

Proven

148

0.29

0.22

432

325

Probable

88

0.27

0.19

234

170

Total Reserves

236

0.28

0.21

665

495

Mineral Reserve Estimate Notes:

1)

Mineral Reserves are reported on a 100% basis as constrained within Measured and Indicated Resources and pit designs included within the mine schedule. The attributable percentage to Capstone Copper is 69.993%. Figures include stockpiles as of June 1 2024 that are scheduled to be processed within the MVO plan. The block model is considered to be fully diluted and no dilution or mining losses are applied.

2)

The pit designs and mine plan were optimized using assumed metal prices of $3.50/lb Cu and $1,500/oz Au.

3)

Mineral Reserves for flotation are estimated above a 0.20% Total Copper (TCu) cut-off.

4)

Mineral Reserves for leach are estimated above a 0.10% Soluble Copper (SCu) cut-off for Dump leach, with a variable Heap cut-off between 0.16% and 0.21% SCu to reflect ore availability. Leach-grade material mined after 2037 was scheduled as waste.

5)

LOM feed to flotation averaged 87.7% total copper recovery and 65.3% gold recovery.

6)

Average heap leach recovery applied in Mine Planning was 71.5% of SCu and 50% of ICu, where ICu = TCu – SCu. Average dump leach recovery applied in Mine Planning was 38.0% of SCu.

7)

Mineral Reserves considered the following average costs: mining cost of $1.87 per tonne moved; $10.11/t flotation processing+tails+G&A; $0.31/lb TC/RC+freight for flotation; $10.14/t heap+G&A; $1.78/t dump leach; $0.35/lb SX/EW costs; and $0.05/lb cathode selling cost. Heap leach Reserve figures include the costs and benefits of bioleaching.

8)

Inter-ramp angles in rock vary from 52° to 59°. The LOM strip ratio is 2.7:1.

9)

Rounding as required by reporting standards may result in apparent summation differences between tonnes, grade and contained metal content.

10)

Grade TCu% refers to total copper grade in percent sent to the mill for metallurgical recovery by flotation. Grade SCu% refers to soluble copper grade in percent sent to the leaching processes. Tonnages are in metric units and contained ounces (oz) are troy ounces.

MINERAL RESOURCE ESTIMATE

Mantoverde estimated the Mineral Resource using drill data available as of October 17, 2022. The database included 5,109 drill holes, totaling 937,629 meters of drilling, with data composited into 10-meter intervals. The estimation was based on a three-dimensional geological model that incorporated interpretations of lithology, mineralization, and spatial relationships relative to the Mantoverde Fault. The orebody was modeled using a probabilistic approach based on indicator models.

Grades of TCu, SCu, Au, cobalt (Co) and calcium carbonate (CaCO₃) were estimated within a three-dimensional block model using Ordinary Kriging interpolation, applied in three progressively larger passes. Variograms were constructed for each of the sixteen estimation units, supporting the identification of ellipsoid anisotropy and linear trends in the data. High-grade outliers were managed through high-yield restriction (HYR).

Mineral Resources were classified using a geometrical variation of the indicator method (metal and tonnage), which models expected errors and provides a confidence level for production volume estimates. This approach helps quantify the estimation errors in production volumes with a defined level of confidence.

The Mineral Resource Estimates are reported inclusive of those Mineral Resources that have been converted to Mineral Reserves, and use the definitions set out in the 2014 Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources and Mineral Reserves (the 2014 CIM Definition Standards). Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

Following is the current Mineral Resource Estimate as at June 1, 2024.

Mantoverde Mineral Resource Flotation – Sulphide + Mixed, Inclusive of Mineral Reserves

 

Category

Tonnage (Mt)

Grade

Contained

TCu %

Au g/t

Co ppm

Cu (kt)

Au (koz)

Co (kt)

Mantoverde Sulphides (Flotation)

Measured

187.5

0.57

0.10

178

1,069

603

33

Indicated

332.0

0.41

0.10

134

1,369

1,068

45

Total Measured & Indicated

519.5

0.47

0.10

150

2,438

1,671

78

Total Inferred

553.1

0.37

0.08

62

2,046

1,423

34

Mantoverde Mixed (Flotation)

Measured

38.9

0.47

0.09

85

183

113

3

Indicated

36.3

0.36

0.09

101

132

106

4

Total Measured & Indicated

75.2

0.42

0.09

93

315

218

7

Total Inferred

17.8

0.29

0.06

30

52

34

1

Mantoverde Sulphides + Mixed (Flotation)

Measured

226.4

0.55

0.10

162

1,252

715

37

Indicated

368.3

0.41

0.10

131

1,501

1,174

48

Total Measured & Indicated

594.7

0.46

0.10

143

2,753

1,889

85

Total Inferred

570.9

0.37

0.08

61

2,098

1,457

35

Mantoverde Mineral Resource Heap and Dump Leach – Oxide + Mixed, Inclusive of Mineral Reserves

 

Category

Tonnage (Mt)

Grade %TCu

Grade %SCu

Contained Cu

(kt)

Mantoverde Oxides + Mixed – Heap Leach

 

 

 

Measured

101.8

0.46

0.35

356

Indicated

63.3

0.40

0.30

190

Total Measured & Indicated

165.1

0.44

0.33

546

Total Inferred

11.5

0.37

0.28

32

Mantoverde Oxides + Mixed – Dump Leach

 

 

 

Measured

153.9

0.22

0.15

231

Indicated

153.3

0.21

0.14

215

Total Measured & Indicated

307.2

0.22

0.15

445

Total Inferred

59.5

0.22

0.14

83

Mantoverde Oxides + Mixed – Heap + Dump Leach

 

 

 

Measured

255.7

0.32

0.23

587

Indicated

216.6

0.27

0.19

405

Total Measured & Indicated

472.3

0.29

0.21

992

Total Inferred

71.0

0.24

0.16

116

Mineral Resource Estimate Notes:

1)

Mineral Resources are inclusive of Mineral Reserves. Mineral Resources, including stockpiles and in situ material, are reported in accordance with the 2014 CIM Definition Standards.

2)

Mineral Resources are reported on a 100% basis. The attributable ownership percentage to Capstone Copper is 69.993%.

3)

Cut-off grade:

3.1. Dump Leach: Oxide: 0.10% ≤ SCu < 0.20% and oxidation state=1, Mixed 0.10% ≤ SCu < 0.20% and SCu/TCu > 50% and oxidation state=2.

3.2. Heap Leach: Oxide: SCu ≥ 0.20% and oxidation state=1, Mixed: SCu ≥ 0.20% and SCu/TCu > 50% and oxidation state=2.

3.3. Flotation: Sulphide: TCu ≥ 0.20% and oxidation state=3, Mixed: TCu ≥ 0.20% and SCu/TCu ≤ 50% and oxidation state=2.

4)

The Mineral Resource pit is based on $4.00/lb Cu and $1,700/oz Au based on long-term forecast pricing.

5)

Tonnes are reported on a dry basis.

6)

Contained Metal (CM) is calculated using the following formulae:

6.1. CM = Tonnage (Mt) * TCu (%) *10 for sulphides

6.2. CM = Tonnage (Mt) * SCu (%) *10 for oxides

6.3. CM = Tonnage (Mt) * g/t Au*1,000/31.1035 for sulphides and Mixed.

6.4. CM = Tonnage (Mt) * Co (ppm)/1,000 for sulphides and Mixed

7)

Flotation recovery is based on a geometallurgical model, 90.44% TCu and 67.87% Au average for Sulphides and 72.77% TCu and 61.73% Au average for Mixed. Heap Leach recovery is based on operating data, expressed in algorithms per mineral model zone considering both SCu and CaCO₃ grades. The average heap leach recovery is 67.64% SCu, with an additional 50% recovery of ICu achieved through the bioleaching process (where ICu = TCu – SCu). For dump leaching, the recovery averages 38.9% SCu, based on operational data.

8)

Tonnage and contained metal have been rounded to reflect the accuracy of the estimate and numbers may not add exactly.

9)

Mineral resources that are not Mineral Reserves do not have demonstrated economic viability.

COMMODITY PRICING

The MV-O FS assumes analyst consensus commodity price assumptions for copper and gold.

Copper

Capstone markets copper concentrate from its four mining operations. Mantoverde copper concentrate is generally considered clean and low in impurities (deleterious or penalty elements). Capstone foresees substantial demand from trading companies that specialize in blending complex materials with cleaner concentrates. These companies typically prefer concentrates like Mantoverde’s due to their compatibility with blending processes and enhanced value proposition. High-quality concentrates are coveted by both smelters and traders alike. This further supports the expected strong demand for Mantoverde’s copper concentrate in the market.

The analyst consensus long-term copper price was determined to be $4.10/lb which is below the current spot price and compares with the five-year trailing average of approximately $3.73/lb. Analyst consensus copper prices in 2025-2027 of $4.30/lb, $4.40/lb, and $4.40/lb, respectively, were used in the economic model.

Gold

The analyst consensus long-term gold price was determined to be $1,800/oz which is below the current spot price and compares with the five-year trailing average of approximately $1,881/oz. Analyst consensus gold prices in 2025-2027 of $2,200/oz, $2,100/oz, and $2,000/oz, respectively, were also used in the economic model.

FURTHER UPSIDE OPPORTUNITIES

The company plans to continue to progress several value enhancement initiatives within the Mantoverde-Santo Domingo district that are not yet incorporated into the base case MV Optimized plan, or the recently announced Santo Domingo 2024 Feasibility Study.

Copper Oxides

Capstone plans to progress drilling and studies regarding the processing of oxide material from Capstone’s neighbouring Santo Domingo and Sierra Norte projects using Mantoverde’s excess SX-EW capacity. To date, oxide materials have been recognized in the shallower portions of the Santo Domingo, Iris Norte, and Estrellita sulphide orebodies. Currently, these oxides are considered as waste material in the recently announced Santo Domingo 2024 Feasibility Study. Meanwhile, only approximately two thirds of processing capacity is being used at Mantoverde’s SX-EW cathode copper plant. Exploration efforts at Santo Domingo will target a potential 80-100 million tonnes of oxide material, which could add up to 10 thousand tonnes per annum of copper production.

Cobalt

A district cobalt plant for the MV-SD district is designed to unlock cobalt production while reducing sulphuric acid consumption and increasing heap leach copper production. The cobalt recovery process comprises a pyrite flotation step to recover cobaltiferous pyrite from the tailings streams at Mantoverde and Santo Domingo and redirect it to the dynamic heap leach pads, which will be upgraded to a bioleach configuration through the addition of an aeration system as part of MV Optimized. The pyrite oxidizes in the leach pads and the solubilized cobalt is recovered via an ion exchange plant treating a bleed stream from the copper solvent extraction plant. The approach has been successfully demonstrated at the bench scale, and onsite piloting commenced in January 2024 at Mantoverde.

As currently envisioned, a smaller capacity countercurrent ion-exchange plant will initially treat cobalt by-product streams from Mantoverde producing up to 1,500 tonnes per annum of cobalt, and following sanctioning of the Santo Domingo project, the facility will be expanded to accommodate by-product streams from Santo Domingo. In line with this, Santo Domingo has initiated a Feasibility Study to assess the optimum process configuration for the pyrite flotation and pumping transportation facilities needed to transport pyrite concentrate to Mantoverde’s leach facilities.

Exploration in the Mantoverde-Santo Domingo District

Capstone has significant untapped exploration potential within MV-SD district. The Mantoverde Optimized plan presented today was prepared without any expansionary drilling campaign since 2019. At Mantoverde, there are 0.2 billion tonnes of Measured & Indicated and 0.6 billion tonnes of Inferred sulphide resources not in reserves. At Santo Domingo, there are 0.1 billion tonnes of Measured & Indicated and 0.2 billion tonnes of Inferred sulphide resources not in reserves. The recently acquired Sierra Norte property also represents an opportunity to potentially be a future feed source in the district. Capstone intends to progress its exploration strategy to service its two eventual processing centers between Mantoverde and Santo Domingo, in addition to continuing to evaluate the potential for Mantoverde Phase II which could include the addition of an entire second processing line at Mantoverde.

NATIONAL INSTRUMENT 43-101

A National Instrument 43-101 («NI 43-101») Technical Report will be prepared to summarize the results of the 2024 Feasibility Study by the Qualified Persons and will be filed on SEDAR+ within 45 days of this news release.

Readers are cautioned that the conclusions, projections and estimates set out in this news release are subject to important qualifications, assumptions and exclusions, all of which will be detailed in the 2024 technical report. To fully understand the summary information set out above, the 2024 technical report that will be filed on SEDAR+ at www.sedarplus.ca should be read in its entirety.

QUALIFIED PERSONS

Peter Amelunxen, P.Eng., Senior Vice President, Technical Services of Capstone Copper, a Qualified Person (“QP”), as defined by NI 43-101 reviewed and approved the content of this news release that is based on the 2024 technical report.

About Capstone Copper Corp.

Capstone Copper Corp. is an Americas-focused copper mining company headquartered in Vancouver, Canada. We own and operate the Pinto Valley copper mine located in Arizona, USA, the Cozamin copper-silver mine located in Zacatecas, Mexico, the Mantos Blancos copper-silver mine located in the Antofagasta region, Chile, and 70% of the Mantoverde copper-gold mine, located in the Atacama region, Chile.

Contacts

Jerrold Annett, SVP, Strategy & Capital Markets

647-273-7351

jannett@capstonecopper.com

Daniel Sampieri, Director, Investor Relations & Strategic Analysis

437-788-1767

dsampieri@capstonecopper.com

Michael Slifirski, Director, Investor Relations, APAC Region

61-412-251-818

mslifirski@capstonecopper.com

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