You have allocated 5 years production @ $15mill free cash flow (...

You have allocated 5 years production @ $15mill free cash flow ( profit would be significantly less) = $75mil free cash flow
Then expect the market to value it at $70 -$100mil Not only are you allowing a valuation up to $25mil more than the resource is worth but you have not allowed for risk or the fact that people expect a return on their capital!

I think you should guess again
cheers