They give three scenarios in the projections and with a 22 yr mine life, even at the low end of the price scale they are doing well. Payback varying from 2-6 yrs..... seems pretty decent.

Average annual pre-tax operating cash flow over life of mine ("LOM")
for the Base Price Case of $434 Million per year, the Low Metal Price
Case of $283 Million, and $1.014 Billion per year for the Market
Price Case.

- Payback on a pre-production capital expenditure of $1.332 Billion,
including contingency of $174 Million, in 4 years for the Base Case,
in 6 years for the Low Metal Price Case, and in 2 years based on the
Market Price Case.