1.1 Project Stages

Project stages organize the investigation, evaluation, engineering and delivery of a mining project. Their purpose is to connect decisions with supporting evidence: whether to investigate further, select a development option, commit capital, begin production or change the operation. Understanding stages requires separating the mine life cycle from technical study levels and engineering design maturity. These distinctions apply to both surface and underground projects, although the investigations and facilities involved differ.

Stages Organize Decisions

The mine life cycle describes the broader progression through exploration, development and construction, operation, closure and subsequent site management. These activities overlap: exploration and development can continue during production, while closure planning begins before construction. An operating mine may also expand or contract as conditions change.^[1]

Technical studies assess development options and their technical and economic justification. Engineering maturity describes how fully the selected systems and facilities have been defined. A feasibility report therefore occupies a different role from a construction drawing package. Study development is iterative; further investigation may require another comparison of options before a final feasibility assessment is appropriate.^[2]

A useful stage definition states the decision being considered, the work needed to support it and the unresolved conditions attached to any approval. Spending on further investigations creates a different commitment from ordering equipment or constructing permanent access. The evidence required should reflect that distinction and the consequences of being wrong.^[3]

Scoping, Pre-Feasibility and Feasibility

The June 2024 CRIRSCO International Reporting Template provides a defined reporting context for these terms. It is advisory; applicable national or regional reporting codes take precedence. Within that framework, the studies have progressively stronger evidence and different purposes:^[4]

Under this Template, a Scoping Study cannot support a Mineral Reserve estimate. At least a Pre-Feasibility Study is needed, together with an appropriate assessment of the factors affecting conversion from resources to reserves; the study label alone does not establish a reserve.^[4]

Terms such as bankable do not guarantee funding. Lenders and owners make their own decisions, and a completed feasibility study still leaves engineering work to support implementation.^[2]

Conceptual, Basic and Detailed Engineering

Engineering phases describe the development of technical definition. A useful functional distinction is that conceptual engineering develops and compares preliminary configurations; basic engineering establishes the selected concept and the main requirements for further design; and detailed engineering develops the documents released for fabrication and construction. For processing facilities, this progression includes process arrangements, layouts and mechanical, structural and automation specifications. Each project's scope and agreed deliverables should make the boundaries between phases explicit.^[5]

These labels should not be assigned automatic equivalents in study level, estimate class or cost accuracy. AACE's estimate-classification guidance makes the maturity of scope-defining information the primary classification criterion. An estimate class neither guarantees estimating quality nor determines a unique accuracy range: uncertainty also depends on the project and its risks. Checking the actual deliverables is therefore more informative than assuming that a stated percentage of engineering completion establishes readiness.^[3]

Developing a Consistent Study Basis

Study maturity depends on the evidence behind the design. Geological interpretation and resource estimates must be suitable for the intended mining assessment. Geotechnical and water investigations inform excavation geometry and water management; processing information informs the treatment route and production assumptions. Mine layouts, sequences, infrastructure and costs then need a consistent basis. CIM's 2019 best-practice guidance emphasizes increasing detail as planning advances and checking the assumptions on which designs depend.^[6]

Environmental and social work develops alongside these technical decisions. For IFC-financed projects covered by its Performance Standards, IFC's 2012 Performance Standard 1 calls for assessment based on appropriate baseline information, with effort related to project scale, location and impacts. It also connects assessment with affected communities, management actions and subsequent review. For stage planning, this supports identifying consequential constraints while alternatives remain open, rather than waiting until the layout has been committed.^[7]

Different disciplines may mature at different rates. Consider a qualitative situation in which a processing facility is well defined but its water supply remains unresolved. A different supply solution could change the facility arrangement, infrastructure, cost and schedule. The review must therefore examine the dependency, not simply treat the completed plant engineering as evidence that the whole project is ready. This illustrates AACE's warning about advanced designs depending on less-developed supporting systems.^[3]

Construction, Operation and Closure

Construction brings the mine, processing facilities and supporting infrastructure into existence. Commissioning tests whether facilities, processes and equipment perform as designed; achieving coordinated production capacity is a further operating challenge. Personnel preparation and environmental protection facilities also belong in the transition to operation.^[1]

Engineering can continue through construction, commissioning and early production. A feasibility study supplies a basis for implementation, but subsequent engineering still has to develop that basis into the work actually executed.^[2]

Once production begins, observations provide evidence for checking earlier assumptions. For example, reconciliation compares resource-model expectations with relevant operating measurements, accounting for stockpiles, dilution and mining losses so that unlike quantities are not confused. Updated excavation information and revised assumptions can then inform mine-plan changes.^[6]

Closure considerations belong in design criteria from the outset. Progressive reclamation may occur during operation, and temporary shutdown needs consideration alongside final closure. Dismantling facilities does not necessarily end site management: monitoring, water treatment or maintenance may remain necessary, depending on site conditions.^[1]

Reviewing Readiness to Proceed

Taken together, these distinctions suggest a practical basis for an internal stage review:

• Define the commitment. Identify whether the decision concerns another investigation, selection of an option, construction expenditure or an operational change.
• Check the evidence. Separate measured information, interpretations and assumptions, and identify which unresolved issues could change the decision.
• Check consistency. Confirm that the mine, plant, infrastructure, environmental provisions, cost estimate and schedule describe the same development case.
• Record the conditions. State remaining work, responsibilities and circumstances that would require reconsideration.

A useful review can conclude that more information is needed, an alternative deserves reconsideration or the project should pause. Its record should explain why the evidence is sufficient for the specific commitment and what remains uncertain. That makes the decision understandable when new information arrives, even if the project later follows a different path.