Phoenix, Arizona--(Newsfile Corp. - February 22, 2023) - Excelsior Mining Corp. (TSX: MIN) (FSE: 3XS) (OTCQB: EXMGF) ("Excelsior" or the "Company") is pleased to announce the results of its Updated Preliminary Economic Assessment ("PEA") on the Johnson Camp Mine Heap Leach, located in Cochise County, southeastern Arizona. The PEA considers the results of the drill program completed in 2022 and the implementation of sulfide leaching technology to improve recoveries. As part of the PEA, the combined report (the "Report") will also include a republishing of the Prefeasibility Study Update ("PFS") on the North Star Deposit of the Gunnison Copper Project. The Gunnison Project is designed as a copper in-situ recovery ("ISR") mine using solvent extraction-electrowinning ("SX-EW") to produce copper cathode and the Johnson Camp mine is a conventional open pit and heap leach operation. Results of the PFS and PEA disclosed in this press release are in United States dollars.
JOHNSON CAMP HEAP LEACH PRELIMINARY ECONOMIC ASSESSMENT
Economic Analysis
The Johnson Camp Mine ("JCM") has historically been an open pit, heap leach operation since Cyprus Minerals opened the property in the 1970's. The operation includes two open pits, a two-stage crushing-agglomerating circuit, a fully functioning SX-EW plant capable of producing 25 million pounds of cathode copper per year, a complete set of PLS and raffinate ponds, and full infrastructure (ancillary facilities, access, power, water, and communications).
Heap leaching of sulfide copper with accelerated pyrite oxidation is proposed in this PEA. The Project plans include mining oxide, sulfide, and transition material from the Burro and Copper Chief pits for 20 years and heap leaching for an additional year to produce copper cathode at a capacity up to 25 million pounds per annum (mppa).
To restart JCM for heap leaching, two developments need to take place simultaneously: pre-stripping and mine development, and the construction of a new heap leach pad, Pad 5. Both are considered to require between six and nine months to complete before irrigation of the new leach pad could commence. Piping of PLS and raffinate lines from Pad 5 to the JCM ponds also fits within this time frame. A PEA has been completed by M3 with respect to this planned re-opening.
Mining of JCM would be by traditional open pit and the highlights of the PEA financial model are tabulated below assuming a copper price of $3.75/lb.
Mine Life and post mining processing | ~20 years |
Heap Leach Material Mined | 85.2 M ton |
Total Copper Grade (CuT%) | 0.37% |
Average LOM Total Copper Recovery* | 77% |
Cu Produced | 492 M lb |
Total Tonnage Mined | 196 M ton |
Initial Mine Capital | $58.9 million |
Total Operating Cash Cost ($/lb Cu)** | $2.24 |
After-Tax NPV/IRR (7.5% discount rate) | $180.0M / 30.4% |
* Total copper recovery includes a combination of oxide, transition and primary sulfide mineral recoveries. ** Includes all operating costs, site G&A, royalties, non-income taxes, salvage, reclamation and closure. |
The table below sets out the sensitivities of the After-Tax NPV and IRR to copper price:
Sensitivity Analysis | |||||
Sensitivity | -20% | -10% | 0 | +10% | +20% |
Cu Price | $3.00 | $3.375 | $3.75 | $4.125 | $4.50 |
IRR After-Tax | 11.5% | 20.9% | 30.4% | 39.9% | 49.2% |
NPV* After-Tax | $32 | $107 | $180 | $251 | $321 |
*million $ at 7.5% discount rate |
The PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the conclusions reached in the PEA will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
Mineral Resources
The JCM Mineral Resources are provided in the table below.
Johnson Camp Mineral Resources
(0.1% CuT cut-off)
Classification | Tons | % Cu | lbs CuT |
Measured | 20,771,000 | 0.31 | 127,545,000 |
Indicated | 87,166,000 | 0.32 | 550,118,000 |
M&I | 107,932,000 | 0.32 | 677,663,000 |
Inferred | 50,998,000 | 0.32 | 322,656,000 |
The JCM copper resources were modeled and estimated using information provided by Excelsior under Mr. Bickel's supervision. The information is derived from historical core holes drilled by Cyprus Mining, Arimetco, Summo USA Corp., and Nord Resources Corp, and new drilling completed by Excelsior in 2022. The drill hole database also includes analyses performed by Excelsior on the historical core. These data, as well as digital topography of the project area, were provided to RESPEC Company LLC ("RESPEC") by Excelsior.
Total copper grades, as well as soluble copper ratios, were interpolated using inverse distance, ordinary kriging, and nearest-neighbor methods. The mineral resources reported herein were estimated by inverse distance interpolation as this method led to results that most appropriately reflected the drill data and geology of the deposit. This is particularly true with respect to the estimation of the lowest-grade areas in the model, where potential over-estimation of volumes could materially impact the resource estimation at grades close to potential open-pit mining cut-offs. The nearest-neighbor estimation was completed for the purposes of statistical checking of the various estimation iterations.
The JCM mineral resources have been estimated to reflect potential open-pit extraction and potential processing by heap leaching. To meet the requirement of the resources having reasonable prospects for eventual economic extraction, a pit optimization was completed using the parameters summarized in the table below.
Parameter | Value | Unit |
Copper Price | $3.75 | $/lb Sold |
Contract Mine Cost | $2.30 | $/ton Mined |
Technical Services | $0.25 | $/ton Processed |
Heap Management | $0.30 | $/ton Processed |
Heap Capital Cost | $0.80 | $/ton Processed |
Crushing/Agglomeration Cost | $1.10 | $/ton Processed |
G&A Cost | $0.05 | $/lb Cu Produced |
SX-EW Cost | $0.25 | $/lb Cu Produced |
Recovery | 95% | Acid Soluble Cu |
Recovery | 95% | Cyanide Soluble Cu |
Recovery | 70% | Sulfide Cu |
Royalty (incl. Stream) | 17.90% | NSR |
Acid Cost | $150 | $/ ton |
Acid Consumption and Costs by Formation | ||
Formation | Acid Cons. lb/ton | Acid Cost $/ton Processed |
Pioneer Shale | 20 | $1.20 |
Bolsa Quartzite | 25 | $1.50 |
Diabase | 30 | $1.80 |
Middle Abrigo | 55 | $3.30 |
Upper Abrigo | 45 | $2.70 |
Lower Abrigo | 40 | $2.40 |
Martin | 70 | $4.20 |
The pit shells created using these optimization parameters were used to constrain the project resources for comparison purposes. An exclusion line was used to limit the pit optimization on the west side of the Burro Pit to prevent the pit optimizations from encroaching on the existing process plant and the historical leach pad. The in-pit resources were further constrained by the application of a cut-off of 0.1% CuT to all model blocks within the optimized pits.
Mr. Jeffrey Bickel, C.P.G., with the independent firm RESPEC of Reno, Nevada, is a Qualified Person as defined by NI 43-101 and is responsible for this mineral resource estimate. He has verified, reviewed and approved the technical disclosure contained in this section of the news release. Mr. Bickel has verified the data underlying the results by reviewing the drilling, sampling, assay, and quality assurance and quality control data, as well as the geologic interpretations completed by Excelsior. Mr. Bickel is not aware of any environmental, permitting, legal, title, taxation, socio-political, marketing or other issues which may materially affect its estimate of mineral resources.
PEA Assumptions
The JCM plan has been developed based on a new mineral resource estimate for the Burro and Copper Chief deposits. The mine plan targets the full resource at Johnson Camp over a 20-year period. A contract miner will be executing the mining of the pits and delivering material to the primary crusher.
Mining of the deposit is expected to be accomplished with 100-ton haul trucks and front-end loaders. Mining is planned on 20-ft bench heights. The pit configuration is double-benched with catch benches every vertical 40 ft. An annual schedule was developed for the mine plan. Crushed and agglomerated material will be processed by placement on the newly permitted leach pad. This tonnage production is limited by the copper production capacity of the existing SX-EW plant of 25 million pounds of copper per year.
The mining contractor is expected to be responsible for mine supervision, equipment operation, equipment maintenance, and blast hole drilling and loading. The reference to specific equipment manufacturers is to illustrate equipment size and is not to be considered a recommendation. Production drilling is expected to be accomplished with Epiroc DM45 class drills or similar. Loading is expected to be accomplished with 14-yard CAT 992 class front-end loaders. Haul trucks are planned to be CAT 777 class 100-ton trucks.
The existing leach pads (Pads 1, 2 & 3) will not be used for future mining for new material extracted from the Burro and Copper Chief pits. The new leach pad area, Pad 5, is to be located northeast of the existing plant facility and is to be designed such that leach solutions flow by gravity into the new combined ILS-PLS pond located down slope of the new leach pad. The PLS solution will be pumped back to the existing JCM SX-EW plant. A storm water pond is also provided.
The Johnson Camp Mine is currently covered under Aquifer Protection Permit P-100514. Excelsior has obtained a significant amendment to the existing APP to accommodate mining at JCM from the Burro Pit. A new facility, Leach Pad 5, with associated impoundments has been added to the existing APP to accommodate resumption of mining at JCM.
The full capital cost for restarting the JCM heap leaching operation including mining pre-production, first fills/Owner's costs, leach pad construction, new leach pad stacking system, crusher and agglomeration refurbishment and haul road construction is approximately $58.9 million. Staffing for the JCM project is mostly in place however several new hires will be needed to augment the existing staff.
JCM Opportunities
JCM Risks
Recommendations
Excelsior should complete the current metallurgical program and, if warranted, proceed to a feasibility study and then detailed engineering for the leach pad and crusher refurbishment.
GUNNISON PROJECT PREFEASIBILITY STUDY
Highlights of the PFS (United States dollars)
A detailed sensitivity analysis to copper price is set out below under the heading "Financial Analysis". In addition, the risks and opportunities associated with the Gunnison Project are discussed below.
The PFS was completed by M3 Engineering & Technology Corporation ("M3") of Tucson, AZ and is effective as of February 1, 2023. The Technical Report (the "Report") summarizing the results of the PFS and prepared in accordance with National Instrument ("NI") 43-101, will be filed on SEDAR and Excelsior's website within 45 days of this news release. The PFS was updated because of the need to update the JCM PEA, which is contained in the same report.
Financial Analysis
The PFS base case generates an after-tax NPV of approximately $1,166.5 million (at a cash flow discount of 7.5%) and an IRR of 37.5%. This financial analysis is based on a number of assumptions which will be fully set out in the Report.
The base case uses the following parameters over the 24-years of production:
FINANCIAL ANALYSIS SUMMARY | ||
Pre-Tax | Post-Tax | |
IRR | 40.6% | 37.5% |
Pre-Production Capital Payback (years) | 6.5 | 6.7 |
NPV (million $) @7.5% | 1,434.8 | 1,166.5 |
COST METRICS | ||
Cost/lb Copper | ||
Direct Operating Costs | 0.945 | |
Royalties, Taxes, Recl. & Salvage | 0.274 | |
Total Cash Cost | 1.225 |
Total initial (pre-breakthrough) capital expenditures (including 15% contingency, EPCM, capital spares, owner's costs, mobile equipment and freight) are estimated at $47.6 million for Stage 1 initial production of copper cathode at approximately 25 million pounds per annum. Total sustaining capital costs over the life of the mine are $1,080.8 million, which includes production wellfield expansion, SX-EW expansion, acid plant construction and water treatment facilities. The average life of mine Direct Operating Cash Cost is $0.945/lb and the average life of mine Total Operating Cash Cost (including royalties, non-income taxes, salvage, reclamation, and closure) is $1.225/lb.
The Company has also evaluated an Alternate case without an Acid Plant. This case generated a pre-tax NPV@7.5% of $1,177.8 million and an IRR of 41.0% (after-tax: NPV@7.5% of $975.5 million and IRR of 38.1%). Total initial capital expenditures remain the same as the "Acid Plant" scenario. Total sustaining capital costs over the life of the mine are $879.7 million, which includes production well-field expansion, SX-EW expansion and water treatment facilities. Average life of mine Operating Direct Cash Costs are estimated at $1.35/lb for the "No-Acid Plant" option with an average life of mine Total Operating Cash Cost of $1.63 per pound.
Sensitivity analysis is shown in the table below.
Base Case After – Tax Sensitivities ($millions)
Copper Price | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $1,167 | 37.5% | 6.7 |
20% | $1,697 | 50.4% | 4.3 |
10% | $1,433 | 44.0% | 6.2 |
-10% | $898 | 30.8% | 7.3 |
-20% | $627 | 24.2% | 8.0 |
Operating Cost | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $1,167 | 37.5% | 6.7 |
20% | $1,031 | 33.2% | 7.1 |
10% | $1,099 | 35.3% | 6.9 |
-10% | $1,233 | 39.7% | 6.5 |
-20% | $1,299 | 41.9% | 6.3 |
Initial Capital | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $1,167 | 37.5% | 6.7 |
20% | $1,160 | 36.1% | 6.7 |
10% | $1,163 | 36.8% | 6.7 |
-10% | $1,170 | 38.2% | 6.7 |
-20% | $1,173 | 39.0% | 6.6 |
The Alternate Case economic after-tax sensitivities are shown in the table below.
Alternate Case After – Tax Sensitives ($millions)
Copper Price | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $976 | 38.1% | 6.0 |
20% | $1,505 | 51.7% | 4.3 |
10% | $1,241 | 45.0% | 4.8 |
-10% | $706 | 30.8% | 6.7 |
-20% | $432 | 23.0% | 7.5 |
Operating Cost | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $976 | 38.1% | 6.0 |
20% | $790 | 32.7% | 6.5 |
10% | $883 | 35.4% | 6.2 |
-10% | $1,066 | 40.8% | 5.4 |
-20% | $1,157 | 43.4% | 5.0 |
Initial Capital | |||
NPV @ 7.5% ($M) | IRR% | Payback | |
Base Case | $976 | 38.1% | 6.04 |
20% | $969 | 36.6% | 6.08 |
10% | $972 | 37.4% | 6.06 |
-10% | $979 | 38.9% | 6.02 |
-20% | $982 | 39.8% | 6.00 |
Mineral Resources and Mineral Reserves
Mineral Resource Estimate
The mineral resource estimate for the North Star Deposit is based on results from 122 drill holes totalling 158,785 feet and is effective as of October 1, 2016 (unchanged from the original 2016 Feasibility Study on the Gunnison Project). The estimate is classified as a measured, indicated or inferred mineral resource, consistent with the CIM definitions referred to in NI 43-101. Excelsior is not aware of any environmental, permitting, legal, title, taxation, socio-political, marketing or other issues which may materially affect its estimate of mineral resources.
Total Resources (Oxide + Transitional + Sulfide) | |||
Resource Class | Short Tons (millions) | Total Cu (%) | Cu Pounds (billions) |
Measured | 200.7 | 0.36 | 1.439 |
Indicated | 710.8 | 0.27 | 3.875 |
Measured + Indicated | 911.6 | 0.29 | 5.315 |
Inferred | 240.9 | 0.22 | 1.070 |
0.05% TCu Cut-off for Oxide + Transitional; 0.30% TCu Cut-off for Sulfide |
Notes:
The North Star mineral resources were modeled to reflect the detailed lithologic, structural, and oxidation modeling completed by Excelsior. Copper mineral domains were interpreted on east-west vertical cross sections on 100-foot spacing, which encompass the 2.3-mile north-south and 1.3-mile east-west extents of the deposit. These domains were then used to explicitly constrain the estimation of copper grades into 50 x 100 x 25-foot (x, y, z) model blocks using 20-foot composites and inverse-distance interpolation. The grade estimation is further controlled by the incorporation of search ellipses that reflect the orientations of modeled structural zones, as well as those of favorable stratigraphic units in areas unaffected by the structures.
All samples were prepared from manually split half-core sections on-site in Arizona. Split drill core samples were then sent to Skyline Assayers & Laboratories ("Skyline") in Tucson, Arizona, an independent laboratory, for Total Copper and Sequential Copper analyses. Skyline is accredited with international standard ISO/IEC 17025:2005 General Requirements for the Competence of Testing and Calibration Laboratories. Analytical results for Total Copper, Acid Soluble Copper, and Cyanide Soluble Copper were reported. Excelsior has no relationship with Skyline Labs other than Skyline being a service provider. Standards, blanks, and duplicate assays are included at regular intervals in each sample batch submitted from the field as part of an ongoing Quality Assurance/Quality Control Program.
Mr. Jeffrey Bickel, C.P.G., with the independent firm RESPEC of Reno, Nevada, is a Qualified Person as defined by NI 43-101 and is responsible for this mineral resource estimate. He has verified, reviewed, and approved the technical disclosure contained in this section of the news release. Mr. Bickel has verified the data underlying the results by reviewing the drilling, sampling, assay, and quality assurance and quality control data, as well as the geologic interpretations completed by Excelsior. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
Mineral Reserve Estimate
The PFS mineral reserve is based on an economic analysis of the mineral resource using a copper price of $2.75/lb and key parameters developed from prior test work. The economic optimization was performed on Measured and Indicated Resources at a cut-off grade of 0.05% Total Cu ("CuT"). EBIT (earnings before interest and tax) was calculated on a resource block-by block-basis using the key economic and technical parameters. For a column of resource blocks to be included in the reserve, the capital costs of establishing the wells for those blocks would have to be less than the combine EBIT for the same blocks. The mineral reserve was estimated after applying engineering and operational design parameters which removed the thinner and deeper portions of the mineral resource. Internal dilution has been included in the final mineral reserve estimate. RESPEC is of the opinion that the mineral reserve estimate derived in this PFS reasonably quantifies the economical mineralization of the North Star Deposit. The reserve estimate is as of October 1, 2016 and the mineral reserves presented in the table below are included in the mineral resource estimate set out above.
North Star Mineral Reserves (Oxide and Transition at 0.05% cut-off)(1) | |||
Category | Short Tons (million) | Total Copper (%) | Pounds of Cu (million) |
Probable | 782 | 0.29 | 4,505 |
Mr. Neil Prenn, with the independent firm RESPEC of Reno, Nevada, is a Qualified Person as defined by NI 43-101 and is responsible for reviewing and approving this mineral reserve estimate. He has verified, reviewed and approved the technical disclosure contained in this section of the news release. Mr. Prenn has verified the data underlying the results by reviewing the drilling, sampling, assay, and quality assurance and quality control data, as well as the geologic interpretations completed by Excelsior.
Risks
A number of risks are highlighted in the Report. Those that are more specific to in-situ mining include:
Opportunities
Opportunities at Gunnison are also highlighted in the Report. Those that are related to in-situ mining include:
Recommendations
A number of recommendations included in the report are aimed at improving wellfield performance, reducing risk, and tightening up engineering and design prior to construction of the raffinate neutralization plant. Excelsior intends to investigate and implement these recommendations prior to further development which include:
TECHNICAL REPORT AND QUALIFIED PERSONS
The Report will be filed on SEDAR and on Excelsior's website within 45 days of the date of this news release. The Report will consist of a summary of the PFS. The Report is being prepared under the supervision of Richard Zimmerman, SME-RM of M3 Engineering & Technology Corporation, Tucson, Arizona, who is a Qualified Person that is independent of the Company. The Report will also receive contributions from the following additional Qualified Persons, who are also independent of the Company:
Each of these Qualified Persons has reviewed and approved the technical information contained in this news release that is relevant to their area of responsibility and verified the data underlying such technical information.
About Excelsior Mining
Excelsior "The Copper Solution Company" is a mineral exploration and production company that owns and operates the Gunnison Copper Project in Cochise County, Arizona. The project is a low cost, environmentally friendly in-situ recovery copper extraction project that is permitted to 125 million pounds per year of copper cathode production. Excelsior also owns the past producing Johnson Camp Mine and a portfolio of exploration projects, including the Peabody Sill and the Strong and Harris deposits.
For more information on Excelsior, please visit our website at www.excelsiormining.com.
For further information regarding this press release, please contact:
Excelsior Mining Corp.
Concord Place, Suite 300, 2999 North 44th Street, Phoenix, AZ, 85018.
Shawn Westcott
T: 604.365.6681
E: info@excelsiormining.com
www.excelsiormining.com
Cautionary Note Regarding Forward-Looking Information
This news release contains "forward-looking information" concerning anticipated developments and events that may occur in the future. Forward-looking information contained in this news release includes, but is not limited to, statements with respect to: (i) expectations for the resolution of carbon dioxide issues and increased flow rates; (ii) the future development plans for the Gunnison Project; (iii) operating and capital costs estimates, along with the economics of the Gunnison Project and JCM; (iv) the intention to mine Johnson Camp and future production therefrom; and (v) the results of the PFS and PEA.
In certain cases, forward-looking information can be identified by the use of words such as "plans", "expects" or "does not expect", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or "does not anticipate", or "believes", or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might", "occur" or "be achieved" suggesting future outcomes, or other expectations, beliefs, plans, objectives, assumptions, intentions or statements about future events or performance. Forward-looking information contained in this news release is based on certain factors and assumptions regarding, among other things, the estimation of mineral resources and mineral reserves, the realization of resource and reserve estimates, expectations and anticipated impact of the COVID-19 outbreak, copper and other metal prices, the timing and amount of future development expenditures, the estimation of initial and sustaining capital requirements, the estimation of labour and operating costs (including the price of acid), the availability of labour, material and acid supply, receipt of and compliance with necessary regulatory approvals and permits, the estimation of insurance coverage, and assumptions with respect to currency fluctuations, environmental risks, title disputes or claims, and other similar matters. While the Company considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect.
Forward-looking information involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by the forward-looking information. Such factors include risks inherent in the construction and operation of mineral deposits, including risks relating to changes in project parameters as plans continue to be redefined including the possibility that mining operations may not be sustained at the Gunnison Copper Project, risks relating to variations in mineral resources and reserves, grade or recovery rates, risks relating to the ability to access infrastructure, risks relating to changes in copper and other commodity prices and the worldwide demand for and supply of copper and related products, risks related to increased competition in the market for copper and related products, risks related to current global financial conditions, risks related to current global financial conditions and the impact of COVID-19 on the Company's business, uncertainties inherent in the estimation of mineral resources, access and supply risks, risks related to the ability to access acid supply on commercially reasonable terms, reliance on key personnel, operational risks inherent in the conduct of mining activities, including the risk of accidents, labour disputes, increases in capital and operating costs and the risk of delays or increased costs that might be encountered during the construction or mining process, regulatory risks including the risk that permits may not be obtained in a timely fashion or at all, financing, capitalization and liquidity risks, risks related to disputes concerning property titles and interests, environmental risks and the additional risks identified in the "Risk Factors" section of the Company's reports and filings with applicable Canadian securities regulators.
Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking information, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. Accordingly, readers should not place undue reliance on forward-looking information. The forward-looking information is made as of the date of this news release. Except as required by applicable securities laws, the Company does not undertake any obligation to publicly update or revise any forward-looking information.
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