They're using 6.5% for both discounting and cost of capital, so...

They're using 6.5% for both discounting and cost of capital, so I'll accept you getting confused. They are different things though. Very different.

On the DCF side - 6.5% is strange I agree. More common standards are 5% (dodgy), 7.2% (doubles every 10 years), 8% (almost industry standard), 10% (conservative), 12% (used by banks to 'stress test' a model), 15% (what should be the industry standard if people were realistic about the risks involved in mining v's banking or manufacturing) and 20% (what used to be the internal standard IRR hurdle for most capital applications until about the year 2000).

On the funding side, all the figures appear to be 'real' rather than nominal. Therefore 'today's' prices and no inflation. Makes it tricky to model, and I suspect metal price forecasts are therefore way too high, but does have a material influence on the effective rate. Depending on timeframe and loan-term, 6.5% real is similar to 8-10% nominal/real-world in a 2-3% inflation environment. Rates should be down to that, or lower, by 2030 so not unrealistic.