Sorry, another correction. I have to adjust for current exchange rate to AUD. (Curently 1 USD to 1.40 AUD) so 60,000 metric tonne required, not 80k.
First stage is likely to produce 25,000t per annum, (maybe more?) so $450,000,000 AUD or so. Then you have to deduct operational costs / taxes etc. It's obviously not pure profit which we must remember.