thanks. just did a quick research over the internet for various projects and am confident about the US$300M CAPEX for 2.4mtpa plant and US$0.45/lb or $110/t of ore zn equiv OPEX
some open cut DFS for lower grade Zn-Pb-Ag projects have opex of US$66/tonne of ore so my $110/t sounds conservative. some underground mines in Canada have CAD$200/t of ore or US$160/t
IBG have US$0.55/lb for opex (excluding smelter) for lower grade ore so my US$0.45/lb sounds conservative. IBG have $500M for 3.3mtpa plant
Note: my revenue assumption includes a 25% reduction for smelter costs; thus US$842M in revenue (including royalty) before smelter costs or $631M after smelter costs
Possibly, the CAPEX might be higher (who knows what they need) & the opex could be lower