The Sounds of Accumulation, page-73

It's not THAT crazy to say the mine is worth $1.5b
At $50 margins, 20 years of mining at 3mtpa gives you $3b in cashflow.
Keep in mind that BBM by itself is permitted to mine at 6mpta. I'm not sure if logistically they could reach that or not. Sharejagger might be able to help.

Say they paid out $2b of that $3b in divvies, that's around $2/share in dividends over 20 years, or $0.10 per year... If you were happy with a 7% yeild, that means the share price would be somewhere around $1.4 which is pretty much bang on a $1.5b market cap.