The plant is 80,000t/yr. The rock mined is mains low grade high dilution, in ore raise development low dilution and gold vein extraction little dilution.
Assume 1/3 of each and grades of 1g/t, 3g/t and 30g/t as guesses so on average 10g/t.
But, there are 3 types of rock, very hard brown dyke, brittle white quartz and combo of circa 3/4 free coarse gold and 1/4?fine arsenopytitic gold.
MCO had high dyke dilution feedingthe plant. After primary crushing it all hits a Vertical Shaft Impactor VSI. The dyke material flogs around in there with a very high recirculating list of 80% (should be 20%) so vastly reduces gold throughput.
Lots of people blame Gekko for poor plants but I have it on good authority that MCO asked Gekko to spec the plant for mainly quartz and not high dilution dyke. Trying to minimise dyke dilution at the underground face is madness.
So also don’t replace VSI but put in ore sorter, first on surface then later underground. Ore sorte removes 99% of dyke material which if at 50% head feed could double if not triple plant throughput with no expansion cost except the $2mill sorter.
Under prior management preliminary samples were provided to Steinert and two months ago the Norton Steinert reports provided to an AUL site manager.
