prism contract, page-4

I have been wondering about a market cap if these 2 come off. Some very, very, very rough figures I have worked out (while writing this) is Bankura worth $500 mil over 30 years and say Prism is worth roughly the same and also assume both have an IRR of 15%. Then working out average over mine or contract lives of 30 years then we have $1 bil over 30 years, so a profit of $150 mill (over 30 years) which equates to an average of $5 mill/year. So from this assume an average PE of 10 so gives a market cap of $50 mill or say around about 17c/share. This gives no value to any other of their operations. Anyone care to add any corrections, extra assuptions etc.