PNX Metals Ltd (ASX:PNX) has identified a new process to increase gold and silver recoveries from the Iron Blow VMS deposit of its Hayes Creek Zinc-Gold-Silver Project in the Northern Territory.
Innovative leaching test work on the Iron Blow float tailings stream indicates the potential for recovery of about 13,000 ounces of gold and 1 million ounces of silver that would otherwise be lost to tails.
The optimisation test work was recently completed and results will feed into a definitive feasibility study (DFS) for the Hayes Creek project.
PNX managing director James Fox said: “We are very pleased with the outcome of this test work as it is something we have been working on in the background for a while.
“To have identified a potential new revenue stream from material that would otherwise end up in tailings is excellent.”
To be incorporated in DFS
The DFS will incorporate a new unit process designed to capture additional gold and silver from Iron Blow float tails that would otherwise remain locked in the mineral lattice and remain unrecoverable.
This work has the potential to increase the robust economics of the Hayes Creek project which were demonstrated by a pre-feasibility study (PFS) completed in 2017.
A newly trialled reagent to specifically target residual gold and silver in the rougher tails has achieved a first pass result of improved recoveries to a scavenger concentrate by 26.6% gold and 19.9% silver.
This concentrate stream was then subjected to three well-known hydrometallurgical processes - intense cyanidation, ferric oxidation at elevated temperatures and pressure oxidation (POx) for extraction of gold and silver.
Intense cyanidation, the preferred treatment route at this stage, achieves additional recoveries of precious metals to solution and then to doré.
Fox said: “Overall gold/silver recoveries have been improved by 10.7% and 17.0% respectively to a new final product being a doré bar, in addition to the zinc and precious metals concentrates as proposed in the PFS.
“This incremental optimisation is continuing to demonstrate that the Hayes Creek Project is a technically, environmentally and financially viable project.”
Assays due this month
Drilling at Iron Blow is complete with thick zones of massive sulphide mineralisation intersected within the eastern and western lodes. Assays are due from late April.
The DFS on the Hayes Creek project has re-commenced and is expected to provide increased confidence in all aspects of the project as well as investigate opportunities to improve mine life and overall project economics.
This would also increase the prospect of favourable development finance terms and structure.
Studies are underway to inform the DFS including those required for government and environmental approvals.
READ: PNX Metals intersects gold mineralisation at Cookies Corner, extending strike to more than 800 metres
Hayes Creek comprises the Iron Blow and Mt Bonnie zinc-gold-silver deposits and the Fountain Head gold prospect, which are less than 3 kilometres apart on wholly-owned mineral leases.
The project is within the Pine Creek region 170 kilometres south of Darwin.