Mining Studies · Stage 2
Pre-feasibility studies (PFS)
A realistic, modifying-factor-supported study that selects the preferred development option, confirms technical viability and underpins a maiden Ore Reserve.
Stage 2 · −15% / +25% accuracy
Proving the case is real
A pre-feasibility study moves a project from “potentially economic” to “realistically viable”. It tests and compares development options in enough engineering detail to select a single preferred case, and it addresses the modifying factors required by the JORC Code.
Critically, a PFS is the minimum study level at which an Ore Reserve can be declared. It is the stage where a Mineral Resource is converted, in part, into an economically mineable Reserve.
The PFS is the decision gate where options become a plan: one preferred case, supported by enough rigour to put a Reserve on the books.
Scope
What a PFS adds over a scoping study
Trade-off studies
Structured comparison of method, scale, cut-off and processing options to select the preferred case.
Engineered designs
Pit and underground designs, access and infrastructure developed to a pre-feasibility level.
Geotechnical inputs
Slope angles, ground support and hydrogeology informed by site-specific data.
Production schedule
A practical schedule reconciled to designs, equipment and development rates.
Cost estimates
Capital and operating cost estimates to roughly −15% / +25%, built from quantities and quotes.
Ore Reserve basis
Modifying factors addressed so Indicated Resources can convert to Probable Ore Reserves.
Process
How a PFS comes together
Define options & basis of study
Set the cases to be tested, the accuracy target and the modifying-factor framework.
Run the trade-offs
Compare mining and processing options to select the value-maximising preferred case.
Engineer the preferred case
Develop designs, schedule and cost estimates for the selected option to PFS level.
Estimate the Ore Reserve
Apply modifying factors so eligible Mineral Resources convert to Ore Reserves, signed by a Competent Person.
FAQ
Pre-feasibility studies, answered
Why is a PFS important?
The PFS is the pivot of the staged study process: it compares development options, locks in the preferred configuration, addresses each JORC modifying factor and is the first study level that can support an Ore Reserve. It converts a promising concept into a defined project with engineered quantities and a credible investment case.
What is included in a pre-feasibility study?
A mine design and life-of-mine schedule for the preferred option, processing and infrastructure definition, capital and operating cost estimates built from engineered quantities, economic analysis with sensitivities, assessment of the JORC modifying factors, and an Ore Reserve statement where the work supports one — consistent with the pre-feasibility deliverables in the AusIMM Study Processes Handbook.
What accuracy does a PFS provide?
Capital and operating cost estimates are typically minus 15 to plus 25 per cent, derived from engineered quantities rather than factored allowances — preliminary designs, schedules and equipment selections priced against cost databases and budget quotations.
Does a PFS justify a final investment decision?
Generally not alone. A PFS confirms viability and selects the development option; a DFS then adds detailed engineering, firm quotations and confirmed test work to reduce estimate risk to the minus 10 to plus 15 per cent band that boards and financiers expect for a decision to mine.
Sources: JORC Code 2012 (jorc.org) · AusIMM Study Processes Handbook — Monograph 35 (2024)
Next steps
Where to go from here
Ready to select a development option?
A PFS confirms technical viability and can underpin a maiden Ore Reserve. Tell us where the project sits and we will scope it.