The Wiluna mining centre is located close to the town of Wiluna, approximately 750km northeast of Perth. Altogether over 4 million ounces of gold has been produced from 20 open pits and 3 underground mines, including the Golden Age mine which is currently a source of high grade free milling ore. All the mines are within 4kms of the Wiluna processing facility. JORC 2012 Mineral Resources are currently 40.8Mt @ 3.9 g/t for 5.2Moz of gold.
Mineralisation is hosted within near-vertical shear zones that range in thickness from 5 to 70m, and generally strike north-south or northeast-southwest. The shear zones flex along strike and down dip, and these flexures in conjunction with favourable host rocks form the best ore zones.
Wiluna ores are either oxide, refractory sulphide, or quartz reef free-milling ores, with most gold occurring within fine-grained sulphides. Both oxide and sulphide gold ores have been treated historically, though only the CIL plant is currently operating, treating oxide ores from both Wiluna and other nearby mining centres. Sulphide ores were processed through the existing circuit for 20 years between 1993 and 2013. The bulk of the existing resource base is sulphide ore and Blackham plans to restart the sulphide circuit to significantly increase gold production.
Blackham’s recently completed an expansion PFS that confirmed the potential to expand production at Wiluna to over 200,000oz pa. Further studies are underway to identify the options that provide the best economic returns based on timing of execution, whether to produce bullion or a flotation concentrate for sale and examining underground bulk mining opportunities, particularly around the East/West underground mines.
The proposed expansion creates the potential for Blackham to join the ranks of Australia’s long life major gold producers.
Key Project Points
- PFS to 200,000oz pa completed Aug ’17 – studies ongoing
- Free-milling oxide and transitional resources and reserves currently being expanded.
- Thick high-grade zones include drill intercepts of 15.4m @ 21.01g/t Au and 19m @ 12.6g/t Au
- New oxide and transitional resources discovered “under the mine head frame”
such as the new Cross-structures pit commenced in 2018.