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United States
Gunnison Mine

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 Location:
83 km E from Tucson, Arizona, United States

  Project Contacts:
Concord Place, Suite 300 - 2999 North 44th Street
Phoenix
Arizona, United States
85018
Phone  ...  Subscription required
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  • Overview
  • Owners
  • Geology
  • Mining
  • Processing
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  • Reserves
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  • Filings & News

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Overview

StageRestarting
Mine TypeIn-Situ
Commodities
  • Copper
  • Sulphuric acid
Mining Method
  • Solution mining
Mine Life24 years (as of Jan 1, 2023)
The Gunnison Copper Project is the world’s most environmentally friendly base metal mining project.

The injection of mining fluids to the wellfield for copper production started on December 31, 2019 and the Company began the start-up and commissioning phase of the project in January 2020. On April 9, 2020 a decision was made to place the project on Care and Maintenance in response to the COVID-19 global pandemic.

Excelsior has recently commenced the ramp-up phase leading to commercial production at the Gunnison Project and has achieved first copper production. However, due to issues related to ramp-up copper production has not yet reached levels that are economically viable.

Excelsior anticipates that with the Gunnison Project commencing production and if appropriate, it acquires additional mineral rights, Excelsior will experience significant growth in its operations.

Well stimulation trials are going to be completed in Q2 2024.


Owners

Source: p. 14
CompanyInterestOwnership
Excelsior Mining Corp. 100 % Indirect
The Gunnison Project is held by Excelsior Mining Corp. through is wholly-owned subsidiaries Excelsior Mining Arizona, Inc. (Excelsior Arizona) and Excelsior Mining JCM, Inc. (Excelsior JCM).

Contractors

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Deposit Type

  • Skarn


Summary:

The Gunnison Project (North Star) lies on the eastern edge of the Little Dragoon Mountains.

The North Star copper deposit is a classic copper skarn (Einaudi et al, 1980 and Meinert et al, 2005).

The North Star deposit is covered by un-mineralized basin fill, varying between 300 and 800 feet in thickness. The mineralized Paleozoic host rocks below the basin fill strike approximately north-northwest and dip 20° to 45° eastnortheast. Baker (1953) recognized three sets of faults in the Johnson Camp area and similar faults have been interpreted in the North Star area. These faults include the “Northeaster” (N10° to 30°E striking; 70° to 75° dip to the SE), “Easter” (N60°E to S60°E striking; 30° to 50° S and higher angle reverse faults dipping 75°S) and “Northwestern” orientations (N15° W strike; steep E or W dip). Only minor displacements are thought to have occurred in the North Star area; however numerous sheared and brecciated faults, generally filled with copper-oxide mineralization, cut through the deposit.

The Paleozoic host rocks have been intruded by the Texas Canyon quartz monzonite along the western margin of the deposit. The intrusion has formed wide zones of calc-silicate and hornfels alteration, as well as extensive low-grade copper sulfide mineralization within the Paleozoic rocks. Metamorphic alteration grading outward from the stock includes garnet-wollastonite-idocrase, diopside, tremolite and chlorite-talc (Kantor, 1977) (Figure ........


Mining Methods

  • Solution mining


Summary:

Excelsior proposes to use the In-Situ Recovery (ISR) method to extract copper from oxide mineralization located within the North Star deposit. ISR was chosen based on the fractured nature of the host rock, the presence of water saturated joints and fractures within the ore body, copper mineralization that preferentially occurs along fracture surfaces, the ability to operate in the vicinity of Interstate 10, and to avoid the challenges of open pit mining in an area with alluvium overburden thickness ranging from approximately 300 feet to 800 feet.

In the ISR process, a low pH raffinate solution (“lixiviant”) is injected into the ore body via a series of injection wells. As the lixiviant migrates through the joints and fractures within the mineralized bedrock, copper is dissolved. This pregnant leach solution (PLS) is recovered by a series of recovery wells that surround each respective injection well.

The PLS is pumped to the surface where the copper is stripped from the solution using the solvent extraction/electrowinning (SX-EW) process. The SX-EW process begins with the SX plant extracting and concentrating the dissolved copper from the PLS, after which the EW plant reduces the concentrated copper to copper cathode. Once the copper is recovered by SX, the barren solution is re-acidified with sulfuric acid to create new lixiviant which is pumped back to the well field and re-injected. The total volume of lixiviant injected and PLS extracted will remain ........


Crushing and Grinding


Processing

Flow Sheet: Subscription required

Summary:

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Projected Production:

CommodityProductUnitsAvg. AnnualLOM
Copper Cathode M lbs 1252,154
Sulphuric acid t  ......  Subscription required


Reserves at October 1, 2016:
The Mineral Resources are estimated at a 0.05% TCu cut-off for oxide and transitional, 0.30% TCu cut-off for sulfide.

The Mineral Reserve are estimated at a 0.50% TCu cut-off.

CategoryTonnage CommodityGradeContained Metal
Probable 782.2 M tons Copper 0.29 % 4,505 M lbs
Measured 200.7 M tons Copper 0.36 % 1,439 M lbs
Indicated 710.8 M tons Copper 0.27 % 3,875 M lbs
Measured & Indicated 911.6 M tons Copper 0.29 % 5,315 M lbs
Inferred 240.9 M tons Copper 0.22 % 1,070 M lbs

Commodity Production Costs:

CommodityUnitsAverage
Cash costs Copper USD  ......  Subscription required
Total cash costs Copper USD  ......  Subscription required
All-in costs Copper USD  ......  Subscription required
Assumed price Sulphuric acid USD  ......  Subscription required
Assumed price Copper USD  ......  Subscription required
* According to 2023 study / presentation.
Subscription required - Subscription is required.

2023 Study Costs and Valuation Metrics :

MetricsUnitsLOM Total
Initial CapEx $M USD  ......  Subscription required
Sustaining CapEx $M USD  ......  Subscription required
Closure costs $M USD  ......  Subscription required
Total CapEx $M USD  ......  Subscription required
Well Field OpEx $M USD  ......  Subscription required
G&A costs $M USD 199.5
Total OpEx $M USD  ......  Subscription required
Income Taxes $M USD  ......  Subscription required
Royalty payments $M USD  ......  Subscription required
Net revenue (LOM) $M USD  ......  Subscription required
Pre-tax Cash Flow (LOM) $M USD  ......  Subscription required
After-tax Cash Flow (LOM) $M USD  ......  Subscription required
Pre-tax NPV @ 10% $M USD  ......  Subscription required
Pre-tax NPV @ 7.5% $M USD  ......  Subscription required
After-tax NPV @ 10% $M USD  ......  Subscription required
After-tax NPV @ 7.5% $M USD  ......  Subscription required
Pre-tax IRR, %  ......  Subscription required
After-tax IRR, %  ......  Subscription required
Pre-tax payback period, years  ......  Subscription required
After-tax payback period, years  ......  Subscription required
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Water Supply
Source: Subscription required

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Proposed Heavy Mobile Equipment as of February 1, 2023:
HME TypeSizeQuantity
Deck & Boom Trucks ....................... Subscription required
....................... Subscription required ....................... Subscription required
....................... Subscription required ....................... Subscription required
....................... Subscription required ....................... Subscription required ....................... Subscription required
....................... Subscription required ....................... Subscription required
....................... Subscription required ....................... Subscription required
Subscription required - Subscription is required.

Mine Management:

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Nov 21, 2023
....................... Subscription required ....................... Subscription required Subscription required Nov 21, 2023
Subscription required - Subscription is required.

Staff:

Total WorkforceYear
Subscription required 2023

Corporate Filings & Presentations:

DocumentYear
Corporate Presentation 2023
Pre-Feasibility Study Report 2023
Annual Information Form 2022
Corporate Presentation 2022
Management Discussion & Analysis 2022
Pre-Feasibility Study Report 2022
................................... Subscription required 2021
................................... Subscription required 2021
Feasibility Study Report 2017
Pre-Feasibility Study Report 2016
Subscription required - Subscription is required.

Subscription required - Subscription is required.

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