The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →A mine’s stated life, production target or expansion is only as credible as the technical plan and execution conditions behind it. Start with the latest filed technical report and issuer disclosures; trace the reserve estimate through the mine schedule, processing plant, infrastructure, costs and permits; then test what happens if key assumptions change. Keep operating results separate from forecasts and conceptual plans.
Start with the right technical report and disclosure regime
Identify the company’s primary listing and the rules that govern the disclosure you are reading. Canadian NI 43-101 requirements and U.S. SEC mining-disclosure rules are separate regimes; do not assume that a filing obligation or study label under one applies to the other.
Find the latest filed technical report, then check subsequent company disclosures for a newer estimate, material change or revised plan. A technical-report filing is required in specified disclosure circumstances; it does not mean every company statement comes with a newly filed report. For written disclosure of Canadian mineral resources and reserves, NI 43-101 calls for the estimate’s effective date, quantities and grades, key assumptions and methods, and known material risks.
Record the report’s effective date, qualified persons, ownership and project scope, and the study stage. A report can become stale when assumptions or project plans change, so reconcile its figures with later issuer announcements rather than treating the report as a permanent guarantee.
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How long is the mine life?
Mine life is a plan built from inputs, not a standalone fact. Trace the planned extraction schedule back to the mineral reserve estimate and examine the assumptions that turn the estimate into a mine plan.
- Check the reserve basis: note the reserve category, quantity, grade, effective date, cut-off criteria and other material assumptions. Understand the basis for converting resources to reserves.
- Follow the schedule: examine when ore is mined and processed, the expected mining rate, and how the plan treats dilution, losses, recovery and mining method.
- Check what supports later years: determine whether the schedule is supported by disclosed reserves or relies on further drilling, conversion of resources, or other future work.
- Compare versions: reconcile older report estimates and schedules with subsequent filings, explaining material differences rather than choosing whichever figure looks more attractive.
Resources and reserves are not interchangeable. Under the SEC study rules reviewed, inferred resources are excluded from a pre-feasibility study’s demonstration of economic viability in support of reserve disclosure; an inferred resource cannot be converted directly to a reserve without new evidence first supporting a higher resource category. Do not treat an inferred-resource inventory as reserve-backed mine life.
What does the study stage tell you?
Study labels indicate how developed the case is, but they do not establish that a project will be built or perform as forecast. Check what work the report actually contains and which assumptions remain unresolved.
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| Stage or status | What to look for | How to interpret it |
|---|---|---|
| Preliminary economic assessment (PEA) | Read the report’s stated scope, assumptions and limitations. The SEC-filed Whistler technical report summary, effective March 2, 2026, says its PEA is not a pre-feasibility or feasibility study and cautions that its assumptions may not be realized. | Treat the economics as an early case with uncertainty, not as equivalent to a later-stage study. The Whistler warning is project-specific, not a claim about every PEA. |
| Pre-feasibility study | Review the detail supporting the mine plan and schedule, modifying factors and economic viability. The SEC rules reviewed distinguish this stage from feasibility by the level of detail and certainty addressed. | A more developed case than an early assessment, but still examine remaining technical, permitting, financing and execution dependencies. |
| Feasibility study | Look for more detailed work on finalized mining plans and schedules, construction and ramp-up, process design and throughput, utilities, infrastructure and permitting. | Greater study detail strengthens the basis for a decision; it does not remove delivery risk or guarantee forecast results. |
| Approved, funded, under construction or operating | Verify the status in current issuer disclosures. For operating mines, compare actual results with guidance over time. | These are distinct execution states, not interchangeable labels. Approval or funding alone is not evidence that a forecast production rate has been achieved. |
Can the mine meet its production targets?
Test the whole operating chain. A mine may have enough scheduled ore but still miss its production target if mining, processing or supporting infrastructure cannot deliver the required rate and product.
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- Mining: compare scheduled rates with the mining method, sequence, equipment needs, dilution assumptions and geotechnical conditions.
- Processing: check plant throughput, recovery evidence, ramp-up assumptions and product specifications. Ask whether metallurgical test samples represent the deposit and whether deleterious elements or other processing factors could affect recovery.
- Inputs and infrastructure: examine power and water supply, tailings and waste arrangements, transport, workforce and logistics where disclosed.
- Operating evidence: for a producing mine, compare guidance and planned rates with reported grade, throughput, recovery and interruptions over time. Distinguish achieved results from targets.
Production should make sense across the schedule, plant capacity and recovery assumptions. A bottleneck anywhere in that chain can undermine the forecast; assess whether the report identifies it and what work or investment is needed to address it.
How much production will an expansion add?
Assess an expansion as a separate case from the current operating plan. Identify the constraint it is meant to remove and connect the incremental output to the work required to remove it.
- Define the change: identify the added production, its expected timing and the constraint being addressed—such as ore supply, mining rate, processing capacity, recovery, power, water, transport or tailings.
- Trace the supporting plan: check whether more output depends on reserve conversion, a plant debottleneck or new plant, additional infrastructure, permits, community arrangements or new contracts.
- Find the decision gates: record what remains to be studied, approved, financed, contracted or built, and whether the estimate includes the additional capital and timing.
- Separate the cases: compare the expansion’s study stage and assumptions with the current mine plan. Do not present conceptual or early-stage output as though it were already part of the operating baseline.
NI 43-101 specifically calls for production economics when a technical report includes a material production expansion. A company’s target or forward-looking production statement remains uncertain until current technical work and execution evidence support it.
Do the economics withstand less favorable assumptions?
Link the economic model to annual production and cash flows. Review commodity prices, grades, recoveries, capital and operating costs, taxes, royalties, discounting and the timing of production. Check whether sensitivities show how returns respond to changes in commodity price, grade, capital, operating costs or other significant parameters. NI 43-101 calls for sensitivity or other analysis using such variations, as appropriate.
Also check cost-estimate maturity. In the SEC rule text reviewed, estimates in the specified pre-feasibility context must state approximately ±25% minimum accuracy and contingency not exceeding 15%; in the specified feasibility context, approximately ±15% minimum accuracy and contingency not exceeding 10%. These are rule provisions for those study contexts, not measured real-world forecast accuracy or a promise that a project will meet its budget.
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Look beyond the model’s headline return. A delay, lower grade or recovery, higher capital requirement, cost inflation or changed production profile can alter annual cash flows. Read the sensitivity analysis alongside the schedule and identify which assumptions have the greatest effect on the case.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What could delay or prevent the expansion?
Review non-geological constraints as part of the investment case, not as footnotes. The Canadian technical-report form calls for discussion of significant risks and uncertainties that could affect the reliability or confidence of resource and reserve estimates or projected economic outcomes. It also calls for relevant discussion of areas including infrastructure, permitting, environmental matters, community issues and closure.
- Infrastructure and operations: power, water, road, rail or port access, tailings, waste management, workforce and material contracts.
- Approvals and relationships: permits, environmental baseline work, community arrangements and other project-specific requirements.
- Economics and execution: capital availability, cost estimates, schedule, markets, taxes and royalties, plus the consequences of delays or changed assumptions.
For each material dependency, note its status, who or what it depends on, and how it could affect timing, capital or output. The existence of a plan or application is not the same as a completed approval, contract or facility.
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Compare alternatives on a like-for-like basis
If a company presents multiple mine plans or expansion cases, separate the current plan from each proposed case and compare the same dimensions. A conceptual expansion should not be compared with an operating base case without clearly identifying their different stages and assumptions.
| Comparison axis | Questions to answer |
|---|---|
| Mine-life basis | How much of the schedule is supported by reserves, and what categories and assumptions support later years? |
| Production profile | How do annual output, grade, throughput, recovery and ramp-up differ? |
| Study maturity | What study stage is each case at, and what technical or modifying factors remain uncertain? |
| Costs and returns | What are the initial and sustaining capital and operating costs, and how sensitive are returns to price, grade, cost and schedule changes? |
| Delivery dependencies | What infrastructure, permits, community arrangements, contracts or financing are still required? |
A practical diligence checklist
- Confirm the applicable disclosure regime and locate the latest technical report and material subsequent filings.
- Record the report date, qualified persons, ownership, project scope and study stage.
- Trace mine life to the reserve estimate and scheduled extraction; identify reliance on resources or future conversion.
- Test whether mining, plant, recovery and infrastructure assumptions support the production profile.
- For each expansion, map incremental output to required capital, approvals, contracts and remaining decision gates.
- Read annual cash flows and sensitivities alongside the production schedule, costs, taxes and royalties.
- Compare operating results with guidance where the mine is already producing, and keep planned results labeled as forecasts.
No broad, independently attributable industry benchmark for mine-life accuracy, production forecast error or expansion success is established here. Evaluate the specific issuer and asset from their current filings rather than substituting an unsupported industry average.
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