RE: Bay(silver) Versus CS (Pozz/Perl)9 Aug 2020 22:40
The 20% is the DCF rate which they've used to put a value on the asset. It's to take into account that money someone says they're going to generate in the future is worth less than money in your pocket now.
Very loosely speaking it's the inverse of the PE ratio, so 20% corresponds to a PE of 5, which would be quite typical for this sort of operation. It's actually a bit more complicated than that, because of the way production ramps up over the years, so for that you'll have to look at the wiki link I gave.
The 70% is just representing the possibility that the whole thing never gets off the ground.
So when they start shipping you can disregard the 70%, but the 20% DCF calculation remains.
Just my amateur understanding, happy to be corrected if wrong. As always DYOR.