LPN You said "The best analogue I have for Hemi is Lake Cowal...

LPN You said "The best analogue I have for Hemi is Lake Cowal which is also refractory. Until they put in their Float Tail Leach system they averaged 80% recovery, now they are a touch below 90%"

Does Lake Cowal ore require Pressure Oxidation treatment? I'm told there are no POX treatment plants operating in Australia. The closest is Lihir Island run by Newcrest in PNG.

Am also told (which aligns with your comments) that the cost of such a plant would be $1bn +.

Been burnt before where ores are treated by a complicated process to extract the metal. That was with HPAL (High Pressure Acid Leaching) and the nickel laterite processing plants owned by Anaconda (Murrin Murrin) and Preston (Bulong).The other one was Centaur with Cawse. The plants were like giant expensive chemistry sets in the desert with large quantities sulfuric acid at temperature and pressure. The plants never operated at full efficiency. "The big risk is not only in proving that the technology works (which no one seriously doubts) but that it can be made to work commercially within a reasonable time." AFR Tim Treadgold Nov 12, 1999 with endless announcements of shutdowns, teething problems etc

Not exactly the same process but am told POX treatment of gold sulfides is not that dissimilar again with large amounts of sulfuric acid at temperature and pressure (what could possibly go wrong?) and quite difficult processes to get working efficiently when done at scale.