Ann: Maiden Vanadium Resource at Taranaki VTM Iron Sand Project, page-29

The problem is the clay host rock that the silver found itself in. One way to de-slime it is to install fine cyclone vortexs and send the overflow to tails and use the "coarse" underflow as the leach feed. From what I understand they never tried this but it would seem an easy way to get the silver out from the interfering crap.

Then reverse the tail/feed outlets when back on gold as the Boppy ore was grind sensitive. The old met from out there explained to me that the finer the grind, the better the recovery. But instead of utilizing the cyclones and having a high circulating load, they put too many tonnes through the mill and gave a coarse feed to the CIL circuit. Which is why (when they turned on the 2ndary mill) the grind "improved" and the recovery went "up to" 78%. But if you look back through the quarterlies they had recovery at 80% one month with no 2ndary mill online. So the earlier ways of running the plant were more effective, but somehow this was abandoned the more MKR ran Boppy dirt through.

There is also preg robbing carbon in the Boppy dirt which is why recovery was low even in BOK days. There are definite ways to counter it but involves technical discussions...

When CCR built the plant, they installed a gravity "circuit" with spirals and tables to try and concentrate the lead in the wonawinta dirt, but it never recovered much above 5%. You need a float plant for lead, not gravity! It wasn't effective for the silver either. It *probably* wouldn't be effective for Boppy gold however as the gold is so finely grained/refractory from Boppy, which also adds to the complexity. You need coarse-ish gold to recovery by gravity.

All IMHO