Recent metallurgical testing by Phoenix Copper Ltd (AIM:PXC, OTCQX:PXCLF) at the Empire Mine in Idaho, US, has further demonstrated the potential for robust copper, gold and silver recoveries using non-cyanide leaching technologies.
After completing test work consisting of crushing, grinding, flotation and both sulphuric acid and ammonium thiosulfate (ATS) leaching on samples collected in 2022, mining consultant Forte Dynamics has identified two potential processes that merit further optimisation, namely flotation plus ATS and flotation plus sulphuric acid leach.
Using the flotation plus ATS method would generate estimated gross revenues of $64.42 per metric tonne, while flotation plus acid leach would generate estimated revenues of $57.8 per metric tonne.
Forte will now optimise both these processes and apply operating and capital costs to the optimisations.
"The results of the metallurgical test work completed thus far on the Empire open pit oxide deposit have further solidified the company's confidence in the project,” stated Ryan McDermott, chief executive of Phoenix Copper.
McDermott noted that the Empire Mine was initially considered a copper project only.
“As a result of further drilling and test work conducted since that time, the Empire Mine has evolved into a robust polymetallic deposit consisting of copper, gold, and silver. These recent metallurgical results show that a number of processes exist, allowing for the recovery of all three metals.”
Deepak Malhotra, metallurgical engineer at Forte Dynamics, said the data collected from the metallurgical test work completed on the Empire Mine project was “very encouraging”.
All test work completed to this point has been performed in an open cycle, but the team is working to optimise the results using locked-cycle testing.
“Locked cycle testing will more closely simulate an active mine environment in which there is a continuous and stable process flow. It is not uncommon to see recovery improvements resulting from locked cycle testing,” noted Malhotra.