Name of the Project
Prominent Hill copper/gold/silver mine expansion.

Location
Gawler Craton, in South Australia.

Project Owner/s
OZ Minerals.

Project Description
An update on the Prominent Hill expansion study has shown that the installation of a 1 360 m, 7.5-m-diameter vertical shaft at Prominent Hill is technically and economically feasible, with capital investment consistent across the interim and strengthened cases.

Construction of the shaft is at this stage assumed to be a conventional blind sink.

A shaft will provide access to the deeper orebody beneath the current ore reserves boundary and provide exploration opportunities beyond the current mineral resource limits.

The update is based on a conservative interim case containing only one-third of the total Prominent Hill inferred resource of 59-million tonnes outside the current life-of-mine plan.

The project has total mineral resources of 150-million tonnes grading 0.9% copper, 0.7 g/t gold and 2 g/t silver. Total proven and probable reserves are estimated at 56-million tonnes grading 0.9% copper, 0.7 g/t gold and 2 g/t silver.

Shaft hoisting is the key enabler that will facilitate increased mine production, from the current four- to five-million tonnes a year to about six-million tonnes a year. Underground ore material will become the sole processing plant feed from about 2025, when the surface stockpiles of remaining openpit material are expected to be fully depleted.

The Prominent Hill expansion will increase the mine’s current life from ten to 11 years.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
Not stated.

Capital Expenditure
The study shows that a shaft haulage expansion will require a capital investment of about A$450-million over a four-year period from 2021.

Planned Start/End Date
Not stated.

Latest Developments
Oz Minerals has approved a A$600-million investment in its Prominent Hill operation, which will increase yearly copper production rates by about 23% and decrease operating costs by about 20%.

The company has approved the construction of a hoisting shaft at the mine, which will extend the mine life from the current 9 years to 15 years, until 2036, at six-million tonnes a year.

The shaft mine expansion also allows for generational province potential, with further mine life extensions possible, as 67-million tonnes of resource remains outside the shaft expansion mine plan.

Operating costs for the expanded operation are estimated at A$64/t, compared with the A$80/t at current rates, while all-in sustaining costs would decline from the current $1.94/t to $1.59/t.

Work on sinking the Wira shaft is expected to start in the first quarter of 2022 and is scheduled for completion in 2024. The shaft operation is expected to start in 2025 at about the same time when the stockpiled ore from the original openpit will be fully depleted. The average copper production is expected to be about 54 000 t/y and 108 000 oz/y of gold after 2025, about 23% more than expected in the current trucking operation.

The hoisting shaft will provide access to mineral resources outside the current trucking mine plan that would have been uneconomical through a trucking operation from about 2033.

Key Contracts, Suppliers and Consultants
AECOM Australia, AGC Consulting, AMC Consultants, Ausenco, BBE Consulting, Beck Engineering Australasia, Boart Longyear, Byrnecut, Coffey, Convergen, D Why, EMM, Emtek, Golders, John Thompson Inclusive, Keaveney Consulting, Land and Water Consulting, Loesche, MCA, Mine Fill Services, Minset, More Space for Light, Newcrest Telfer Operations, Newmont Tanami Operations, Noble Environs, Pete Holliday, Redpath, Pells Sullivan Meynink, RUC, SAGE Automation, SRK Consulting, Stantec International Consulting, Strategy Focused Innovation, Woodgrove and Xylem Water Solutions (expansion study); and Hatch, IA Engineering, Optiro, SimSAGe, Stantec International Consulting, Strategy Focused Innovation and SRK International (peer review).

Contact Details for Project Information
OZ Minerals, tel +61 8 8229 6600 or email info@ozminerals.com.