I was wrong about the NPV. Depending on the assumptions one makes, even with X paying 100% CAPEX and getting 50% metal, Garatouw still has a very healthy NPV.
There are NPV calculators online that you can have a play with.
The mistake I made was assuming all the CAPEX was going to be spent in the first year ($800 million). This is clearly wrong! :-)
The other assumptions I made were a discount rate of 10% and a margin per ounce of $1,000.
Ralph