Potential mine O/P and profit in 2020

Just thought I'd throw some numbers out there. With all approvals going well and ml being awarded soon (note this is assuming all goes well), it is obvious that all will be done to get a mine working by 2020. Based on this say we have a medium sized mine of 2.5 million tonnes of ore at 3% would give us 75000 tonnes of zinc concentrate. If we assume an IRR of 15% and a conservative price of $2400/tonne of zinc concentrate (according to various reports it could be somewhere near $4000/tonne by then owing to mine closures and no new discoveries), we would have the following:
Incoming 75000X2400 = $180,000,000
IRR of 15% is 180,000,000X0.15 = $27,000,000
If shares on issue are the same at the time then this is approx. 2.7c/share profit. Could be very interesting if we ever get a mine up and running!