It's acutally a lot more simple.  NPV is based on cash flow in and cash flow out, period.

If they use copper at $3.50 US and that all the major improvements reduces the total cost around $1 to $1.25 US, that's 790M to 875M US of profit per year, when considering production of 350Mlbs CuEq LOM.

If the timeline is still 5 years to build, that should provide a pre-tax NPV (8%) around 3B to 3.7B US.

MoneyK