Capstone Announces Mantoverde Optimized Feasibility Study
October 1, 2024
Capstone Announces Mantoverde Optimized Feasibility
Study
(All amounts in US$ unless otherwise indicated)
Vancouver, British Columbia – 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
o 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%
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.
NEWS RELEASE
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o 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
o 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 (“NPV 8%”) 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:
o Processing of oxide material from Capstone’s neighbouring Santo Domingo and Sierra Norte
projects using Mantoverde’s excess SX-EW capacity
o Recovery of cobalt and additional copper from a pyrite concentrate
o 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.
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
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
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