You appear to be correct on those figures. (Learning a bit...

You appear to be correct on those figures. (Learning a bit here). But it looks like, from the chart, that the sulphuric acid concentration may be reduced even further as no drop in efficacy occurred when dropped from 20% to 4% . If it can be dropped to 1% the the cost of the acid drops to $3.50/t. The weathered rock in the top 20 metres, they have stated is easier to grind, ? less than $10/t cost. So you are looking at > $10/t in savings there. Definitely would need those 2 costs reduced.

Of course if more of the breccia zone rock can be found then the value of the ore jumps from $125/kg to $300/kg x the recovery 80% x your payability factor 75% x 0.33kg/t = $59/t minus the big costs of ore crushing <$10/t - acid $3.50/t. The margins here would be very good I would think.