Mineral Resource Estimate (“MRE”)
The updated MRE for Volcan was prepared by Micon International Limited (“Micon”) of Toronto, Canada in accordance with the CIM definitions and standards for Mineral Resource Estimation. The tabulated mineral resources for the Volcan Project are set out in Table 1.
The mineral resources are considered as all potentially profitable blocks using the base case input parameters that are contained within the US$1,800/oz Au optimized open pit shell and below the topographic surface. The mineral resources are stated using the gold grades estimated by the Ordinary Kriging interpolation method and using capped metal grades.
The MRE is effective as of July 22, 2022. Mineral resources which are not mineral reserves do not have demonstrated economic viability.
Micon has considered the mineral resource estimates in light of known environmental, permitting, legal, title, taxation, socio-economic, marketing, political and other relevant issues and has no reason to believe at this time that the mineral resources will be materially affected by these items.
Table 1: Mineral Resource Estimate for the Volcan Project, Effective Date July 22, 2022
| Category | Tonnage (kt) |
Au Grade (g/t) |
Au Content (k. oz) |
| Measured | 123,979 | 0.700 | 2,792 |
| Indicated | 339,274 | 0.643 | 7,013 |
| M+I | 463,253 | 0.658 | 9,804 |
| Inferred | 75,018 | 0.516 | 1,246 |
Notes on the MRE:
- The updated mineral resources are reported at a cut-off grade of 0.29 g/t gold for the Dorado Oeste (DO) and Dorado Este (DE) and are reported at a cut-off of 0.75 g/t for Dorado Central.
- The effective date of the updated mineral resource estimate is July 22, 2022. Tonnages and metal content in the table are rounded to the nearest thousand, thus, numbers may not total precisely due to rounding.
- The mineral resources are reported according to the latest edition of the CIM definitions and standards which was adopted by the CIM council on May 10, 2014.
- Mineral resources which are not mineral reserves do not have demonstrated economic viability. The estimate of mineral resources may be materially affected by environmental, permitting, legal title, market conditions and other modifying factors. At the time of this report, Micon’s QPs have not been able to determine any factors that would adversely impact the current mineral resource estimate.
The updated MRE was used as a basis for a Preliminary Economic Assessment of the Project.
Preliminary Economic Assessment (“PEA”)
Tiernan commissioned Ausenco Chile (“Ausenco”) to compile a PEA of the Volcan Project with an overall effective date of March 15, 2023. The PEA was prepared in accordance with the Canadian disclosure requirements of National Instrument 43-101 (NI 43-101) and in accordance with the requirements of Form 43-101 F1.
The responsibilities of the engineering companies who were contracted by Tiernan to prepare this report are as follows:
- Ausenco managed and coordinated the work related to the report, reviewed the metallurgical test results and developed PEA-level design and cost estimate for the process plant, general site infrastructure, environmental and economic analysis
- Deswik Brazil (“Deswik”) designed the mine pit, mine production schedule, and mine capital and operating costs
- Micon International Limited (“Micon”) completed the work related to geological setting, deposit type, exploration work, drilling, exploration works, sample preparation and analysis, data verification and developed the mineral resource estimate for the Project
- Gestión Ambiental Consultores (“GAC”) conducted a review of the environmental studies of the Project
Readers are cautioned that the PEA is preliminary in nature. It 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, and there is no certainty that the PEA will be realized. Commodity prices can be volatile, and there is the potential for deviation from the forecast.
The Volcan property is located approximately 700km north of Santiago, the capital of Chile, approximately 170km by road east of the mining and agricultural city of Copiapo and approximately 40km west of the border with Argentina. The property is located in Region III of northern Chile in the Province of Copiapo and political subdivision of Comuna Tierra Amarilla.
The total area controlled comprising the Volcan Project is 45,289ha, corresponding to the actual property boundaries. However, a title and claim search indicates that Tiernan, through its subsidiary Andina Chile, holds 55,172ha because several areas have duplicate (overlapping) registered concessions under the various Chilean categories of mineral rights holdings. The 55,172ha are made up of 55 mining properties, 139 exploration concessions and one exploration application owned by Andina.
Andina Chile owns water rights which have been developed in two wells located approximately 21km from the resource area and 5km east of the northern end corner of the Volcan concessions.
Mining Methods
The mine layout and operation are based on the following criteria:
- Two independent open-pit areas named Dorado Oeste/Central and Dorado Este, each one with a dedicated Non-Economic Rock Storage Facility
- Independent access from both pits to the mine run of mine (ROM)/crushing pad
- Low-grade stockpiling near the ROM/crushing pad
- 20m height benches
The life of mine (LOM) runs for 14 years. The basis for the scheduling includes:
- Plant feed of 60 ktpd.
- Maximum 85 Mt of material movement per year.
- Low-grade stockpiling to increase head grade for initial years.
Metallurgical Testwork
Three major phases of test work were conducted. The first consisted of initial leach, flotation tests, and comminution tests to assess the potential of the Volcan Project. This early phase of work culminated in the last published NI 43-101 Technical Report entitled “Technical Report on the Results of the Pre-Feasibility Study on the Dorado Deposits, Volcan Gold Project, Region III, Chile” dated January 31, 2011 (the “PFS”) and published on SEDAR by Andina Minerals Inc.
This was followed by more detailed work to optimize process conditions and considerations., Andina carried out a further phase of test work in 2010, 2011 and 2012 to support a potential feasibility study for the Project.
Recovery Methods
The plant is designed to process material at a rate of 60,000 t/d with an average head grade of 0.63 g/t of Au. The plant is designed to be operated 24 hours per day, 365 days per year.
The process plant includes the following units, processes, and facilities:
- primary crushing of ROM
- overland conveyor system to transport coarse material
- coarse material stockpile
- secondary crushing and screening in closed circuit
- tertiary crushing (HPGR)
- agglomeration and heap stacking
- heap leach pad and ponds
- sulphidisation, acidification, recycling, and thickening (SART) plant
- Adsorption, Desorption, and Recovery (ADR) - carbon-in-column (CIC), Desorption and Regeneration, and Refinery.
Environmental, Permitting and Social Considerations
The Project is in the Andean highlands area of the Atacama Region, which is characterised by extreme environmental conditions for biotic development. In this area, hyper-arid conditions, intense solar radiation, high wind speeds and daily surface freezing of watercourses constitute adverse conditions for ecosystems. Human settlements are also scarce, due to the lack of available water resources and the hostile climatic conditions during the winter, with the exception of lands used by Indigenous communities, some tourism and conservation activities.
Capital Cost Estimates
The cost estimates were developed according to the requirements for a AACE Class 5 Estimate, with an expected accuracy range of -30% to +50%.
The total initial capital cost estimate for the Volcan Project is $900.1m; sustaining capital cost is $276.4m; and the total project cost is $1,176.5m. Table 2 provides the Project cost summary for initial and sustaining capital cost.
Table 2: Summary of Capital Costs
| Description | Initial Capital | Sustaining Capital | Total Capital |
| Mining | 71.0 | 16.0 | 87.0 |
| Process | 331.7 | 146.2 | 477.9 |
| Infrastructure – On site | 58.1 | - | 58.1 |
| Infrastructure – Off site | 75.9 | - | 75.9 |
| Total Direct ($m) | 536.8 | 162.2 | 699.0 |
| Project Indirect Cost | 143.4 | 52.4 | 195.7 |
| Owner Cost | 38.8 | 13.2 | 52.0 |
| Contingency | 181.1 | 48.7 | 229.8 |
| Total Capex Class 5 ($m) | 900.1 | 276.4 | 1,176.5 |
Operating Cost Estimates
A summary of the individual components that make up the LOM operating costs is presented in Table 3. Mine operating cost weighted averages are indicated separately for the Years 1-10 which correspond to the active mining period and Years 11-14 which corresponds to low grade stockpile rehandle only.
Table 3: Summary of Operating Cost Estimate
| Area | Units | Avg. Y 1 – Y10 Mining |
Avg. Y11 – Y14 Stockpile Rehandle Only |
Avg. LOM |
| Mining | $/t moved | 1.88 | 0.66 | 1.76 |
| Mining | $/t processed | 6.48 | 0.66 | 4.94 |
| Processing | $/t processed | 6.61 | 6.60 | 6.61 |
| G&A | $/t processed | 0.99 | 0.59 | 0.88 |
| Total Operating Cost | $/t processed | 14.08 | 7.86 | 12.44 |
Economic Analysis
The economic analysis was performed assuming an 5% discount rate. Cash flows have been discounted to the beginning of construction on January 1, 2028, assuming that the Project execution decision will be made and major project financing will be carried out at this time.
The pre-tax net present value (NPV) discounted at 5% (NPV5%) is US$1,254 M, the internal rate of return (IRR) is 25.0%, and payback is 3.4 years. On an after-tax basis, the NPV5% is US$826 M, the IRR is 20.5%, and the payback period is 3.6 years. A summary of the Project economics is included in Table 4.
Table 4: Economic Analysis Summary
| General | LOM Total / Avg |
| Gold Price ($/oz) | 1,800 |
| Mine Life (years) | 13.6 |
| Production | LOM Total / Avg |
| Total Plant Feed Tonnes (kt) | 293,165 |
| Plant Feed Head Grade Au (g/t) | 0.63 |
| Leach Recovery Rate Au (%) | 64.2% |
| Total Gold Ounces Recovered (koz) | 3,820 |
| Total Average Annual Gold Production (koz) | 281 |
| Average Year 1 to 10 Annual Gold Production (koz) | 332 |
| Operating Costs | LOM Total / Avg |
| Total Operating Costs ($/t Processed) | 12.44 |
| Cash Costs* ($/oz Au) | 921 |
| AISC** ($/oz Au) | 1,002 |
| Capital Costs | LOM Total / Avg |
| Initial Capital ($m) | 900 |
| Sustaining Capital ($m) | 276 |
| Closure Costs ($m) | 30 |
| Financials - Pre-Tax | LOM Total / Avg |
| NPV (5%) ($m) | 1,254 |
| IRR (%) | 25.0% |
| Payback (years) | 3.4 |
| Financials - Post-Tax | LOM Total Avg |
| NPV (5%) (US$M) | $826 |
| IRR (%) | 20.5% |
| Payback (years) | 3.6 |
* Cash costs consist of mining costs, processing costs, mine-level G&A, copper revenue credit, refining charges and royalties over payable gold ounces
** AISC includes cash costs plus sustaining capital and closure cost over payable gold ounces
Sensitivity Analysis
A sensitivity analysis was conducted on the base case pre-tax and after-tax NPV, IRR, and Payback of the Project, using the following variables: metal price, discount rate, leach recovery, initial capital costs, and operating costs. Analysis revealed that the Project is most sensitive to changes in metal price, leach recovery, then, to a lesser extent, to operating costs and initial capital costs.
Table 5 and Table 6 presents a summary of the Sensitivity Analysis.
Table 5: Sensitivity Analysis Pre-Tax Summary
| Gold Price | Base Case | Total Capex | Total Opex | |||
| NPV (5%) | IRR | -30% | 30% | -30% | 30% | |
| $1,400 | $202 | 8.8% | $521 | ($118) | $947 | ($543) |
| $1,600 | $728 | 17.4% | $1,047 | $408 | $1,473 | ($18) |
| $1,800 | $1,254 | 25.0% | $1,573 | $934 | $1,999 | $508 |
| $2,000 | $1,780 | 31.9% | $2,099 | $1,460 | $2,525 | $1,034 |
| $2,200 | $2,305 | 38.4% | $2,625 | $1,986 | $3,051 | $1,560 |
Table 6: Sensitivity Analysis Post-Tax Summary
| Gold Price | Base Case | Total Capex | Total Opex | |||
| NPV(5%) | IRR | -30% | 30% | -30% | 30% | |
| $1,400 | $82 | 6.7% | $330 | ($175) | $609 | ($551) |
| $1,600 | $459 | 14.1% | $697 | $213 | $972 | ($81) |
| $1,800 | $826 | 20.5% | $1,058 | $587 | $1,328 | $305 |
| $2,000 | $1,188 | 26.3% | $1,415 | $954 | $1,678 | $676 |
| $2,200 | $1,544 | 31.5% | $1,767 | $1,316 | $2,023 | $1,041 |
PEA Interpretations and Conclusions
Based on the assumptions and parameters presented, the PEA shows positive economics (i.e., $826 M post-tax NPV (5%) and 20.5% post-tax IRR). The PEA supports a decision to carry out additional detailed studies.