Name and Location
Stockman copper/zinc project, Victoria, Australia.

Client
Independence Group.

Project Description
An optimisation study completed on the Stockman copper/zinc project, which comprises the Wilga and Currawong deposits, has incorporated the 2013 feasibility study to further derisk and improve the project returns.

The project has a total proved and probable reserve of nine-million tonnes, grading 2.1% copper, 4.5% zinc, 39 g/t of silver and 1.1 g/t of gold.

The scope of the project encompasses concurrent development of the two underground deposits to feed a central one-million-tonne-a-year differential flotation concentrator that will produce an average of about 140 000 t/y of copper and zinc concentrates over an estimated ten-year project life.

The concentrate products will be exported to customer smelters in the southern Asia region.

The project will use conventional mechanised sublevel open stoping with cemented paste backfill as the primary mining method. The key mining fleet will consist of modern hydraulic development jumbos and long-hole stope drills, 17-t-capacity loaders, 50 t to 60 t dump trucks, as well as a variety of ancillary equipment.

The Wilga deposit has an existing decline access that was partially refurbished in 2011 and remains accessible, reducing the preproduction development requirements significantly. Typical decline access will be 5. 5 m wide by 5.8 m high.

Ground conditions are generally good and water ingress is low. The Currawong and Wilga deposits are relatively shallow for underground mines and, therefore, the haulage and ventilation requirements are modest and development lead times short.

The Stockman concentrator will be designed for a nominal throughput rate of one-million tonnes a year and will comprise:
• a three-stage crushing circuit,
• a ball mill and IsaMill grinding circuit,
• a differential copper/zinc flotation circuit,
• concentrate thickening and filtration,
• concentrate storage, blending and containerised transport to port, and
• tailings thickening and paste backfill manufacture and/or a subaqueous tailings storage facility disposal.

Net Present Value/Internal Rate of Return
The project has a net present value at a discounted rate of 10% of $146-million and an internal rate of return of 25%, with a payback period of 3.3 years.

Value
The optimisation study estimates capital expenditure at $259-million – a decrease from $359-million in the feasibility study.

Duration
Not stated.

Latest Developments
Independence will continue to advance the project, with the critical path being to secure a range of licences from the commonwealth government and the various Victorian agencies, which could take 12 to 18 months.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Independence Group, tel +61 8 9238 8300, fax +61 8 9238 8399 or email contact@igo.com.au.