I agree DC14. The 8% 'chosen by TCK' is the value that is stated in the Teck Agreement to test the BFS economics. At this discount, the project need only return one single $1 to be 'positive'. TCK may well have another discount %age that it uses privately for these types of projects.

Indeed the difference of between 5% and 8% is huge. By my numbers and current 3 yr metal prices the NPV at 8% would be about $10.45B. At 5%, the NPV becomes $14.183B. A difference of $3.733B!!! That is quite a bit of wiggle room for those with the sharper pencils.