The scoping study completed nearly four years ago gave the...

The scoping study completed nearly four years ago gave the following parameters:-
NPV @10% discount rate =US$73m
Cash costs US $0.48lb
Capex US$132.5m
Price per lb of copper $0.90.
Scoping studies tend to be optimistic, but there have been good results since then.
Other notable changes-price of copper ,(use US1.30lb?), a rise in chemical charges for every SX-EW operation(ask MRX!), and a substantial increase in construction costs (steel,concrete etc).
Ball parking the above, I have used a 35% increase in capex (US$46m giving a fresh capex for H4 of around US$180m), lifted the cost per lb of copper to 58cents, and added in copper at US$1.30.
The NPV of the free cash flow in the scoping study was us$73m plus the capex of US$132.5m, ie US205.5m based on a margin of 90c (revenue) less 48c (Cost) of 42c.
That margin is now closer to $1.30 less 58c, ie 72c-a rise of 70%.
Lift the discounted free cash flow by this amount gives a figure of US$350m (US$205 times 170%). Deduct the increased capex of US$180m leaves an NPV around US$170m compared to the earlier figure of US$73m.
The previous figures were marginal-ie a net return of $73m on an outlay of $132.5m.(IRR 21%)
This looks a lot better-a net return of $170m on an outlay of US$180m.
Please note the above is very much back of the envelope and does not include a value for the massive western porphyries which are an order of magnitude larger again.
As a final disclaimer-I still hate the place, and have only thrown this in for curiosity sake.
Cheers,TAS