With current copper prices at about $14,541 per tonne, Austral Resources (ASX:AR1) sees an opportunity to re-mine the legacy heap leach pads to recover acid-soluble copper remaining in the ore at its Mt Kelly asset.
The copper producer says the process only requires a small rehandling excavator, without the need and cost of mining, hauling, and crushing.
The heap leach circuit is expected to be re-mined and re-irrigated within the next 12 months and become an added source of production for the company.
Announcing today the results of a mineral resource estimate (MRE) for the existing Mt Kelly Heap Leach stockpile on Austral’s heap leach pads (MKHL), neighbouring the Mt Kelly treatment plant, the company says the Heap Leach stockpile is considered an important additional resource to the company.
Further testwork and studies will assist Austral in increasing confidence in the MRE and determining appropriate next steps to determine the feasibility of re-mining the Heap Leach stockpiles.
Progression of the heap leach re-mine is expected to provide Austral with a pathway to low-cost production. The Mt Kelly processing plant was commissioned in October 2007 under the ownership of Copper Co, which was then sold to CST Minerals in 2009.
The total ore mined, crushed, and treated via Heap Leach to date is 22.6Mt at an average grade of 0.85% copper.
It is estimated that there is circa 45,000t of residual copper metal in-situ and unrecovered for various reasons; some of which include the premature over-stacking of ore prior to the terminal recovery being reached due to historically aggressive mining/processing campaigns.
Previous operators employed a mining fleet that was two to three times the size of what was required resulting in over mining and exceeding the run of mine (RoM) capacity, which put pressure on the processing circuit, and ultimately resulted in over stacking these pads prematurely.
The company notes legacy recoveries averaged 77% prior to Austral taking over the operation.
Write to Adam Orlando at Mining.com.au
Images: Austral
