Cornerstone Capital Resources Inc. (TSX-V:CGP) (OTC:CTNXF) (FWB:GWN1) is pleased to announce the results of the Pre-Feasibility Study for the Cascabel copper-gold porphyry joint venture project in northern Ecuador in which Cornerstone has a 15% interest financed through to completion of a feasibility study and repayable out of Cornerstone’s share of project earnings, plus 6.85% of the shares of joint venture partner and Project operator SolGold Plc, for a total direct and indirect interest in Cascabel of 20.8%.
The PFS confirms the Cascabel project’s potential to be a large, low-cost, and long-life mining operation that is based on achievable, proven, and tested mining and processing assumptions. Once constructed, Cascabel is expected to be a top 201 South American copper & gold mine benefiting from a high-grade core, advantageous infrastructure and an increasingly investor friendly government. The mine is expected to produce a clean copper-gold-silver concentrate expected to be sold to Asian and European smelters.
Figures referenced in this news release can be viewed through the following link:
Cornerstone CEO, Brooke Macdonald, commented:
“The PFS confirms the great potential of the Alpala deposit which we view as a step towards daylighting value across the entire Cascabel concession. We undoubtedly believe that Cascabel is a multi-generational asset with strong cash flow generation potential. The PFS supports our view that Cornerstone’s 20.8% strategic direct and indirect stake in Cascabel is extremely valuable.”
SolGold’s MD & CEO, Darryl Cuzzubbo, commented on the PFS:
“I am extremely pleased to announce the results of the pre-feasibility study for the proposed Cascabel mine in Ecuador. In essence, it supports what we have believed all along – that this project is no ordinary mining asset. Cascabel will be a significant, multi-decade and very low cost producer of copper that can help enable Ecuador’s emergence as the next copper frontier at a time when the world needs copper the most as we transition to a net zero carbon emissions future.
This project is economically attractive and based upon assumptions that we believe can be delivered upon. There is further upside that will be explored over the coming months and the next phase of the project as we seek the necessary Government approvals to move into early works and execution.
Such a project will create over 6,000 indirect and direct jobs, and bring significant royalty and tax revenue benefiting all Ecuadorians.”
SolGold’s Chair of the Cascabel Project Steering Committee, Keith Marshall, commented on the PFS:
“I am very encouraged with the pre-feasibility study. It offers, what I consider to be, a robust but flexible solution for the development of the underground mine at Cascabel. The study focused on the “right sizing” of the project, with the objective of reducing the technical and execution risk. It also provides a straightforward approach to mining the deposit that optimizes selectivity, without compromising any of the resource and maintaining optionality.
I am confident that the study lays the solid groundwork for the next steps in the Cascabel project. I am particularly looking forward to progressing the study work and being able to expand our operational activities in Ecuador.”
SolGold’s Director and former CEO, Nick Mather, commented on the PFS:
“The various upsides at Cascabel offered by additional mineralized porphyry systems still being outlined and assessed, potential for additional production and treatment plant capacity, refinements to the mine plan, continued low cost of capital and what I see as the opportunity for long run higher copper prices as the world electrifies, suggest that this project indeed has considerable further upside to be evaluated.”
SUMMARY OF CASCABEL PFS RESULTS
The PFS investigated multiple scenarios to identify an initial base case to take forward, with additional resources and upside to be investigated, supporting the next phase optimizations, and confirming the application of block cave mining to the Alpala underground resource.
Attractive initial cave project, potentially delivering:
An initial Mineral Reserve estimate for the Cascabel project of 558Mt, with 0.58% Cu, 0.52 g/t Au and 1.65 g/t Ag for 3.3Mt Cu, 9.4Moz Au and 30Moz Ag.
Exploration success and future potential with unexplored areas identified for future drilling and extension of additional reported resources.
The PFS underpins the Mineral Reserve estimate and further optimizations of the mine and process plant are expected to deliver additional value.
The availability of low-cost hydropower, on site water resources, the use of targeted underground mining, process plant configuration, the potential use of an electric mining fleet, concentrate transport via a pipeline are expected to deliver a lower carbon footprint compared to projects which do not have these benefits.
The Cascabel project DFS is planned for completion in H2 CY23, with additional optimizations including:
See Table 1 on next page for an economic and operating summary of the PFS.
|Key PFS outcomes
(100% project basis; US$ million unless otherwise noted)
|AET – 2 12||Spot
|Economic assumptions||Copper (US$/lb)||3.60||4.20||4.74|
|Government royalty rate||3% (base & precious metals)|
|Ecuador tax rates13||15% profit share / 25% corporate|
|Initial project LOM||26 years|
|Total ore mined||558 Mt|
|Average copper grade / recovery||0.58% / 87.1%|
|Average gold grade / recovery||0.52 g/t / 72.1%|
|Average silver grade / recovery||1.65 g/t / 65.7%|
|Total CuEq produced8||4.5 Mt|
|Total copper produced||2.8 Mt|
|Total gold produced||7.6 Moz|
|Total silver produced||21.7 Moz|
|Annual CuEq production (peak/average)7, 8, 9, 14||391 kt / 212 kt|
|Annual copper production (peak/average)7, 9, 14||210 kt / 132 kt|
|Annual gold production (peak/average)7, 9, 14||829 koz / 358 koz|
|Annual silver production (peak/average)7, 9, 14||1.4 Moz / 1.0 Moz|
|Operating||Average net cash cost (US$/lb Cu)||(0.40)||(0.66)||(0.63)|
|Average AISC (US$/lb Cu)||0.06||(0.20)||(0.17)|
|Financials||Pre-tax NPV (8%)||$5,241||$6,915||$7,862|
|After-tax NPV (8%)||$2,907||$3,781||$4,083|
|Capital payback period||4.7 years||4.3 years||4.2 years|
|Total FCF generation||$14,413||$16,080||$16,278|
|Average annual FCF||$740||$856||$863|
|Average annual FCF (first 5yrs post ramp-up)||$1,345||$1,575||$1,699|
|Average annual EBITDA||$1,156||$1,396||$1,540|
|Average annual EBITDA (first 5yrs post ramp-up)||$2,040||$2,419||$2,622|
Table 1: Economic and operating summary
An accelerated energy transition would increase copper demand growth with a faster uptake of electric vehicles and renewable energy generation, both industries having high copper intensities. The Cascabel project concentrate is expected to be a clean high value concentrate, with low levels of deleterious elements, sought after by smelters globally. Wood Mackenzie’s AET-2 long-term copper price forecast is US$4.20/lb and is based on projections that conform to a 2-degree or lower global warming scenario. At this price, and assuming current spot prices for gold and silver, SolGold estimates an after-tax project NPV of US$3.8bn and 22% IRR.
Cascabel is located in northern Ecuador approximately three hours’ drive north of Quito, the capital city of Ecuador. Access is via sealed highways through the closest major centre of Ibarra, located approximately 80 km south of the property. Infrastructure in the region and throughout Ecuador is generally of a high standard, with excellent road access, power, and water sources readily available in the local area.
The PFS process commenced in 2020 with a revision to scope in 2021 to investigate the ‘right’ capacity block cave for the Alpala underground, and corresponding right sizing and expansion of the process plant to suit. Extension opportunities, alternate mine access methods and tailings storage facility options were also considered during the PFS.
The block cave will be mined with Load Haul and Dump equipment to one of two primary crushing stations on the trucking level. Both diesel and battery electric vehicles were assessed during the PFS, including the potential benefits for mine ventilation requirements. For the PFS the block cave design was based on diesel vehicles in all applications except BEV for the production trucking loop. Further investigations for electrification are proposed in the DFS.
Mineral Resource Estimate15
The Alpala porphyry copper-gold-silver deposit, at a cut-off grade of 0.21% CuEq, comprises 2,663 Mt at 0.53% CuEq16 in the Measured plus Indicated categories, which includes 1,192 Mt at 0.72% CuEq in the Measured category and 1,470 Mt at 0.37% CuEq in the Indicated category. The Inferred category contains an additional 544 Mt at 0.31% CuEq.
The MRE comprises a contained metal content of 9.9 Mt Cu and 21.7 Moz Au in the Measured plus Indicated categories, which includes 5.7 Mt Cu and 15.0 Moz Au in the Measured category, and 4.2 Mt Cu and 6.6 Moz Au in the Indicated category. The Inferred category contains an additional 1.3 Mt Cu and 1.9 Moz Au.
|Cut-off grade||Mineral Resource category||Mt||Grade||Contained metal|
|Measured + Indicated||2,663||0.53||0.37||0.25||1.08||14.0||9.9||21.7||92.2|
Table 2: Cascabel project Alpala underground mineral resource estimate.
Mineral Reserve Estimate
The Mineral Reserves have been estimated for a block caving method and take into account the effect of mixing of indicated material with dilution from low grade or barren material originating from within the caved zone and the overlying cave backs. The initial Mineral Reserve represents only 21% of Measured and Indicated Resources tonnes and approximately 38% of contained metal.17
|Mineral Reserve category||Mt||Grade||Contained metal|
Table 3: Cascabel project Alpala underground mineral reserve estimate.
Access to the Alpala underground mine is expected to be via twin declines commencing from a boxcut located near the surface and the first lift near the 300mRL. Mining is planned to be a Block Caving mining method, whilst all horizontal development will be undertaken utilising conventional drill and blast practices. The vertical development for the main ventilation rises will be excavated using blind sinking methods.
Mine production design for the block cave incorporated findings from detailed geotechnical and hydrogeological assessments, to determine the height of draw based on recommended draw bell spacing. Lower grade draw points on the west of the footprint were included in preference to those in the east to generate a smaller span option. Current geotechnical guidelines inform to commencing the cave on the eastern side, expanding to the west, causing a small delay in higher grade draw points in the centre.
Initial access to the footprint will be via an early access blind sunk shaft to the southwest of the deposit. This will link to a twin decline mined from the north of the deposit with a portal adjacent to the process plant. In the longer term the decline will be the main access path.
The shaft is used to gain early access to the footprint, where it is used to mine long lead time excavations on the footprint, primarily the crusher chamber and access to the collection chamber under the crusher chamber.
The declines are accessed from two separate portals. The second portal location is for the conveyor only, located in proximity to the process plant location. The first portal is located further to the south to reduce the critical path distance to the footprint. An overview concept of the lateral and vertical accesses is shown in Figure 1.
The portals are located in a boxcut approximately 3,000m from the orebody. They have been positioned in close proximity to major surface infrastructure including the processing plant due to the nature of the surrounding terrain. It allows a direct route for the ore to the processing plant without the requirement to build surface haulage routes in mountainous terrain. This eliminates material handling issues that would be apparent if the portals were located elsewhere.
The mine design has been developed to enable all infrastructure including the primary crushers to be off set from the cave abutment zone in accordance with geotechnical recommendations. The infrastructure design in this PFS has assumed loader tramming from drawpoint to ore pass, to loadout stations for a truck haulage loop, terminating at the tip points for the crusher feed bin/s, located outside the caving zone (Figure 2).
In addition to the initial access shaft and the access and conveyor declines, the PFS design includes shafts for ventilation. Each of these shafts is designed to suit the ventilation requirements for the steady-state operating mine. The early access shaft will also become a source of fresh air intake once all early access requirements are completed, and the decline development reaches the footprint.
Sufficient refuge chambers will be located in disused stockpiles and cuddies to accommodate the number of personnel working underground (expected to be highest during the construction phase when mechanical/civil works are being undertaken to install the materials handling system in addition to underground miners).
The twin decline provides a second means of egress, with the early access shaft another potential egress method. During the development of the footprint, small boxholed escapeway rises may be required between the undercut and extraction levels depending on the schedule.
Process Plant (Figures 3 & 4)
The crushed ore from the underground primary crushers will be conveyed to the surface and fed to the secondary crushing circuit. The product from the secondary crushing area will be conveyed to the fine ore stockpile, and subsequently reclaimed to the high-pressure grinding rolls (“HPGR”) circuit. The product from the HPGR circuit will report to a grinding circuit consisting of ball mills, each operating in closed circuit with a hydrocyclone cluster.
The ground product will report to conventional rougher flotation. The rougher concentrate will be reground using stirred mills and will be subsequently upgraded within the cleaner flotation circuit to produce a saleable flotation concentrate. Cleaner flotation tailings are further processed through conventional flotation cells to recover gold and silver contained within pyrite. Pyrite concentrate is thickened and subjected to a conventional cyanide leach/carbon in pulp extraction followed by an Anglo American Research Laboratory gold recovery circuit. Sludge electrowinning cells recover gold and silver from eluate for smelting to doré bars in the gold room.
The flotation concentrate will be thickened using a high-rate thickener and then pumped via a pipeline to the Esmeraldas port facility. Two tailings streams will be produced from the flotation circuit, namely the rougher tailings and the cleaner scavenger (or pyrite) tailings, requiring disposal within the tailings storage facility. These tailings streams will be thickened separately using high-rate thickeners prior to independent pumping to, and disposal to at the TSF. The TSF design is based on regulatory and best practice standards and guidelines, including ANCOLD 2019 and the Global Industry Standard on Tailings Management established by The International Council on Mining and Metals, the United Nations Environment Programme and the Principles for Responsible Investment.
The concentrate slurry will be received by an additional thickening stage at the Port facility. The concentrate will then be dewatered using Larox continuous cloth vertical tower filters. The resulting filter cake will be stockpiled within a covered facility until reclaimed for seaborne transportation.
Process water will be recycled from the thickener overflows and supplemented with treated water from the underground mine. Additional make-up water to the process water system will be provided from the raw water supply drawn from the on-site catchment dam. Raw water will be also used for potable water production, gland seal service for the slurry pumps, cooling water make-up, reagent preparation, and fire water supply.
Indicative Production Profile (Figure 5 & 6)
Following mining optimization studies, the production profile for the Cascabel project is based on a process plant nameplate capacity of 25Mtpa from the underground block cave at the Alpala deposit. The project is expected to reach nameplate capacity in the fourth year from the start of process plant operations with first ore expected in mid-2029.
Initial process plant production totalling 2.8Mt of copper, 7.6Moz of gold and 21.7Moz of silver.
The PFS mine plan targets the Alpala high grade core with copper grades expected to average over 0.75% (~1.35% copper equivalent) over the first 10 years of production.
Metal recoveries to the copper gold flotation concentrate are based on equations fitted to the locked cycle test work results and in general indicate good to very good fits of the data.
Copper concentrate grade is based on mass recovery to concentrate and copper recovery to concentrate.
Metal recoveries to doré are estimated based on limited test work results. Whilst the pyrite concentrate is amenable to cyanidation, but further test work is required to further define the metal recovery to the pyrite concentrate and the metal recoveries to doré.
Capital Cost Estimate
The capital cost estimate meets the requirements for a pre-feasibility Study consistent with the Association for the Advancement of Cost Engineering (“AACE International”) cost estimating guidelines for a Class 4 estimate. The estimate accuracy range of ±25% is defined by the level of project definition, the time available to prepare the estimate and the amount of project cost data available.
The total capital cost estimate for the Cascabel project is summarized in Table 4.
|Tailings storage facility||309||695|
Table 4: Cascabel project capital cost estimate
Pre-production capital totals US$2.7bn and includes all costs up to first ore to the process plant. Post-production costs required to achieve production ramp-up to design capacity and sustaining capital are estimated to total US$2.1bn.
Operating Cost Estimate (Figure 7)
The Cascabel block cave operation is estimated to have a low unit mining cost (operating and sustaining) of US$6.51/t. Total average gross unit cash costs inclusive of treatment charges and government royalties are US$1.72/lb of payable copper. AISC costs inclusive of gold and silver by-product credits are estimated at US$0.06/lb Cu over the 26-year mine life and averaging US$(1.38)/lb in the first five years from achieving nameplate capacity, positioning Cascabel well within the first decile of the global copper industry cost curve. Net cash costs are estimated at US$(0.40)/lb Cu. Negative cash costs reflect significant precious metals by-product contributions, primarily gold, providing downside protection to lenders.
Cash Flow Generation (Figure 8)
Cascabel’s indicative production profile and low operating costs are expected to support strong after-tax free cash flow generation totalling nearly US$14.5bn over the 26-year initial mine life and averaging US$740m annually.
Environmental, Social and Governance
Project operator SolGold has stated it is committed to the social and environmental sustainability of its projects and being a leader in this space within Ecuador. As SolGold advances the Cascabel project, clearly defined criteria will be reported as studies advance into development and operations.
As a minimum, SolGold considers the following criteria immediately applicable not only from a corporate perspective but also to its activities within countries where SolGold has interests:
SolGold has built strong community partnerships over the last decade in the country and has an extensive engagement process that will be continued through the Environmental Impact Assessment stage.
Ecuadorian law requires that an EIA be conducted prior to authorisation of construction and operations. In addition to Ecuadorian requirements, SolGold will ensure that the EIA is compliant with appropriate international standards. At minimum, these would include consideration to the applicable Equator Principles, the International Finance Corporation (“IFC”) Performance Standards and Environmental, Health, and Safety Guidelines, as well as Sustainable Development Goals (“SDG”) which align with the development of the Cascabel project and the effected regions.
In anticipation of advancing the permitting processes within Ecuador, environmental baseline studies within the Cascabel tenement are well advanced.
SolGold will be evaluating several options as part of the DFS to manage and minimise the project’s overall carbon footprint. These include maximising power from hydro generation sources, further investigations on electrification, assessing process integration to optimize operational efficiency, among other initiatives.
SolGold is continuing on its journey toward compliance with the UK Corporate Governance Code and intends to be compliant with all aspects of the code from mid-2022.
A sensitivity analysis was performed on the base case after-tax NPV to examine the sensitivity to commodity prices, capital costs and operating costs.
The Cascabel project is most sensitive to changes in the copper and gold prices as well as capital costs; less sensitive to changes in operating costs, and least sensitive to changes to silver prices. Figure 9 and Table 5 show the results of the after-tax analysis.
of project (US$M)
|Copper Price (base US$3.60/lb)|
|Gold Price (base US$1,700/oz)|
Table 5: Metal price and discount rate sensitivity analysis
Outstanding Opportunities and Upside Options
The Cascabel project optimizations which will be progressed include:
The Cascabel project DFS is planned for completion in H2 CY23. SolGold plc is currently progressing additional optimizations in preparation for the DFS that will be included in a PFS Addendum planned for completion in H2 CY22.
SolGold plans to engage with the relevant government departments from Q2 CY22 to commence fiscal discussions and the permitting process.
SolGold intends to release a National Instrument 43-101 technical report on Cascabel within 45 days of this release.
The Qualified Persons for the “Cascabel Project, Ecuador, NI43-101 Technical Report on Pre-Feasibility Study”, that has an effective date of 31 March 2022, are detailed in the table below.
|Mineral Resource Estimate||Cecilia Artica, BSc MSc RMSME||(formerly) Mining Plus|
|Mineral Reserve Estimate||Aaron Spong, BEng FAusIMM CP (Min)||Mining Plus|
|Environment, Social, Tailings & Water||Tim Rowles, BSc MSc FAusIMM CP RPEQ||Knight Piésold Pty Ltd|
|Metallurgy||Peter Gron, BSc FAusIMM||Wood plc|
|Process Plant & Infrastructure||Steve Klose, BEng MSc FAusIMM||Wood plc|
|Financial Evaluation||Kirk Hanson, MBA PE||Wood plc|
|Marketing||Christopher Heath, BSc Hons PhD FAusIMM||Wood Mackenzie|
Yvan Crepeau, MBA, P.Geo., Cornerstone’s Vice President, Exploration and a qualified person in accordance with National Instrument 43-101, is responsible for supervising the exploration program at the Cascabel project for Cornerstone and has reviewed and approved the information contained in this news release.
Cornerstone Capital Resources Inc. is a mineral exploration company with a diversified portfolio of projects in Ecuador and Chile, including the Cascabel gold-enriched copper porphyry joint venture in northwest Ecuador. Cornerstone has a 20.8% direct and indirect interest in Cascabel comprised of (i) a direct 15% interest in the project financed through to completion of a feasibility study and repayable at Libor plus 2% out of 90% of its share of the earnings or dividends from an operation at Cascabel, plus (ii) an indirect interest comprised of 6.85% of the shares of joint venture partner and project operator SolGold Plc. Exploraciones Novomining S.A. (“ENSA”), an Ecuadoran company owned by SolGold and Cornerstone, holds 100% of the Cascabel concession. Subject to the satisfaction of certain conditions, including SolGold’s fully funding the project through to feasibility, SolGold Plc will own 85% of the equity of ENSA and Cornerstone will own the remaining 15% of ENSA.
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