Refractory Gold, page-14

Is it? Refractory is defined as ore that recovers less than 80% using conventional (CIL/CIP) gold leaching processes (AKA free milling). Lake Cowal is ~85%.

Lake Cowal flow sheet is crush, grind, float, regrind, CIL. I can't see any sulphide destruction processes that would indicate that that Lake Cowal is refractory.

The difference is in the sulphide complex. Lake Cowal has pyrite, sphalerite, galena and chalcopyrite, while Youanmi has pyrite and arsenopyrite. Arsenopyrite is the nasty one, the one that typically makes a deposit refractory and difficult to process.

Lake Cowal takes advantage of the ability to float the sulphides and process the two streams separately to improve their reagent (and cost) consumption.