Hi Astro,
A quick look over the 2018 numbers (from the annual report) gives us some idea.
$30m mining costs
1.8Mt ore mined
1.7Mt ore treated
160kt conc produced
(Round numbers)
Now, this doesn't account for variations in stripping ratio or mining costs since 2018, but in round number estimates, that is a bit under $20/t of ORE mined, and a bit under $200/t of CONCENTRATE produced.
So, although the contaminated stockpiles are slightly lower grade and will incur some costs for pre-treatment, they have already effectively expensed somewhere approaching $200/t of concentrate in mining costs for this stockpiled material.
Hope this helps!
Happy to be corrected!
Cheers
GCar
2018 numbers