The Stockman project is located in north east Victoria, approximately 470km northeast of Melbourne. The project currently holds three Exploration Leases and one Mining Lease covering approximately 42 sq kms.
The development concept consists of two underground mines - the historic Wilga Mine which previously operated in the 1990s, and a new mine to be developed at Currawong including process plant, supporting infrastructure and accommodation village.
The Currawong mine will be the main ore source for the project and Wilga ore will be blended with Currawong ore to optimize production.
The mine will have a combined annual mining rate of 1.0Mtpa of ore over an initial nine year mine life, feeding an on-site process plant producing copper and zinc concentrates containing an average 30kt CuEq per year.
The mines will use conventional long hole stoping and backfill mining methods, with ore trucked to surface.
A new process plant with a 1Mtpa nameplate capacity will be built at the Currawong mine. Ore will undergo conventional crushing and grinding before being treated using sequential flotation to produce copper and zinc concentrates containing silver and gold by-products.
The concentrates will be loaded into steel half height storage containers for transport via road train to port for shipping to local and overseas smelters.
Tailings from the process plant will be used to produce paste fill for backfilling underground mining voids. Surplus tailings will be placed in the existing surface tailings storage facility which will be recommissioned during construction.
An on-site gas-fired power station and a 218 room accommodation village will be required to support the operation and the project workforce. The project construction phase will take approximately two years, with pre-production capital expenditure to total approximately $250 million.
In February 2021, the Round Oak Board approved funding to commence the Definition Phase Study for the project which will build upon the Selection Phase Study completed in 2019.
This is the final step prior to the Project going to the Board for approval to commence construction. Following Board approval, it will take approximately 3 years for the project to complete construction and commissioning and begin commercial production.
All primary approvals are in place for the development of the project and the secondary approvals required to progress to construction will be obtained as part of the Definition Phase Study process.
The Stockman Project is located in the Omeo Zone of the Lachlan Fold Belt and contains two deposits – Wilga and Currawong.
Stockman is a subseafloor style replacement style mineralization, with the deposits hosted within the Gibson’s Folly Formation, which is comprised of interbedded siltstone, volcaniclastic sediments, and extrusive and intrusive volcanics ranging in composition from rhyolite to basalt.
The Wilga mineralisation comprises a single lens of copper-rich and zinc-rich massive sulphide (pyrite-sphalerite-chalcopyrite dominant) with less abundant pyrite-chalcopyrite-chlorite stringer mineralisation.
The Wilga deposit occurs 50–150m below the surface, near the base of the Gibson’s Folly Formation. Currawong is hosted by the same sequence as Wilga and contains five separate lenses (A,B,J,K & M) occurring from 90–300m below the surface with strong structural control.
The massive sulphide lenses have a strike extent of approximately 300m, a down-dip extent of approximately 240m and a maximum thickness of around 37m.
Stockman also boasts a series of highly attractive regional exploration targets, with two additional inferred mineral resources defined within the mining lease (Eureka and Big Foot) but not included in the current mine plan.
There is an extensive geochemical database (surface and stream sediment samples) across the project, and to date all in-situ geochemical surface anomalies which have been drilled have intersected mineralization. Several geochemical surface anomalies are yet to be drill tested.
Aerial geophysical surveys have been effective in generating exploration targets within the initial 100m below surface, but increased depths remain open.
More than 10 highly prospective drill-ready targets are located in close proximity to the Wilga and Currawong deposits.
Almost 1000 holes have been drilled to date, totalling 136km, of which 77% have been within existing resource areas.
Of the 247 exploration holes not within existing resources only 95 were drilled beyond a depth of 100m.
The number of prospective geochemistry targets along with the open exploration space beyond 150m depth provides significant upside for the project including potential life and scale increase.
The Stockman deposits were discovered by WMC Resources/BP Minerals in 1978 and 1979 and first developed by Denehurst Ltd from 1992 to 1996, during which time 955,000t were mined producing 215K tonnes of copper concentrate and 48K of zinc concentrate.
In 1996, Denehurst ceased all mining activities at Wilga with liability for the abandoned site eventually transferred to the Victorian state government which oversaw surface rehabilitation works (mill site, tailings storage area, core farm) in 2005/06.
In June 2007, the Stockman Project was acquired by Jabiru Metals Ltd following a competitive tender conducted by the Victorian Government. Jabiru Metals was later acquired by Independence Group (IGO) in June 2011, and IGO discovered the Eureka and Big Foot lodes in close proximity to the Currawong deposit in 2012 and 2013 respectively.
Round Oak Minerals Pty Ltd (then CopperChem Pty Ltd), acquired the project from IGO in December 2017 and continued to progress the permitting and approvals process.