Ann: Maiden Reserve at Bulletin to drive step-change, page-162

Or, another option for CAI
Float a high grade sulphide concentrate and sell it .
Small float plant is not capital intensive .
its the oxidation part that is horrendously expensive ( roasting, biox or autoclave)
that’s assuming the gold is locked in a sulphide matrix that can economically be floated of course.
most ( not all) refractory gold ores are pretreated by flotation to produce a concentrate for oxidation. It reduces the volume and increases the S content ( necessary for autogenous ignition)
Brucejack in Canada is an example of a significant mine that does this ( though for environmental reasons , not economic)
may be worthwhile. Any metallurgy worth his salt will know this, hopefully Calidus investigating the possibility.
solves a lot of issues if they can.