The PFS was done in 2019 and I assume you're using the numbers from it. I have no idea what numbers should be used since they continued drilling and in 2021 they reported results like   

• Drillhole FSDH049 returned 425.3m at 1.55% CuEq (0.42% Cu; 0.44g/t Au; 91.5g/t Ag); included within the long intercept, was the highest-grade silver intersection on the project to date , with 4m at 5,045.0 g/t Ag from a depth of 236m contained within a broader silver interval of 56m at 629.1 g/t Ag from a depth of 228m .

   Check their 3 year price chart and you'll see when their share price took off. Check the 2021 press releases and you'll see why they have an insane market cap of just under 2 billion. BHP is spending couch change to mark their territory on a project that contains a monster deposit.