17.1 Scoping, Pre-Feasibility & Final Feasibility Study Maturity

A feasibility study is a decision system, not a thick report. It integrates deposit knowledge, design, testwork, approvals, execution, cost, schedule, market, environment, community, and risk to determine whether to stop, investigate, select an option, or invest. Study names imply progressively greater definition, but the exact nomenclature and accuracy expectations depend on the reporting code, corporate standard, lender, and project context.

Typical Study Progression

Scoping or Conceptual Study

The study asks whether plausible development concepts merit further work. It compares broad mining and processing alternatives, identifies fatal flaws, frames scale and infrastructure, and establishes exploration and testwork priorities. Inputs can include lower-confidence Mineral Resources where the applicable reporting code permits, but results must not be presented as a Mineral Reserve or definitive development case.

Pre-Feasibility Study (PFS)

A PFS evaluates alternatives sufficiently to select a preferred technically and economically viable option. It develops mine method and schedule, process route, site layout, waste and tailings concept, infrastructure, environmental and social baseline, project execution, cost, and financial analysis. Under resource-reporting frameworks, a PFS commonly supports applying Modifying Factors and may support Mineral Reserve conversion by a Competent Person when all criteria are met.

Feasibility Study (FS)

An FS develops the selected option to the level needed for a final investment decision, financing, detailed execution planning, and permit support. It requires stronger design definition, testwork, quantities, vendor or market input, schedule logic, risk treatment, and management plans. “Feasible” still depends on assumptions and approvals; it is not a guarantee of construction or performance.

Coordinated Maturity

A study is only as strong as its critical dependency. Detailed plant engineering cannot compensate for weak orebody geometry. A measured resource does not compensate for absent tailings capacity or no water source. Key workstreams include:

Estimate Accuracy and Contingency

An estimate range describes expected uncertainty under a defined scope and methodology. It is not achieved by declaring a study stage. Quantity definition, vendor quotations, local productivity, market date, escalation, foreign exchange, taxes, indirects, owner costs, and schedule all affect accuracy.

Contingency covers uncertainty within the defined project scope; it should be risk-based. It is not a hidden budget for undefined scope, management optimism, escalation, or a known omitted facility. Separate contingency, escalation, growth allowance, and management reserve according to the estimate basis.

Study Basis Document

Record:

• objective and decision;
• data cut-off and responsible persons;
• resource and reserve basis;
• design criteria and alternatives;
• production, recovery, and ramp-up;
• currency, base date, inflation, exchange, and tax;
• estimate methods, quotations, exclusions, and contingency;
• schedule calendars and critical path;
• environmental, social, closure, and permitting basis;
• risks, opportunities, sensitivities, and unresolved work; and
• recommendation and next gate.

Option Selection

Use multi-criteria analysis carefully. NPV is important, but an option that cannot be permitted, operated safely, supplied with water, or closed credibly is not preferable. Weight safety, environment, community, technical risk, schedule, flexibility, and economics. Run sensitivity so a small scoring change does not disguise a fragile choice.

Exam Scenario

A project has detailed equipment quotations but only two metallurgical composites from a geologically variable deposit. The plant estimate appears precise, yet recovery and flowsheet selection are not mature. The correct response is targeted variability sampling and testwork before representing feasibility-level confidence; adding decimal places or generic contingency does not solve the missing evidence.

Study-Level Trap

More detail in one discipline does not upgrade the whole study. A feasibility-level process design attached to conceptual geotechnical, water, tenure, or closure work remains constrained by those immature dependencies. State the maturity of each critical input and the resulting limit on the project decision.

Maturity Must Be Balanced

Study confidence is not the average maturity of its chapters. A detailed plant quote cannot compensate for an untested ore type, an unsupported water source, missing tailings capacity, unresolved access, or a schedule that precedes permits. At each gate, identify the least-mature dependency capable of changing the selected concept or value, define the evidence needed, and prevent estimate-class labels from implying certainty the inputs do not possess.