update:
i decided to do some cut and paste.

from the pa

    -   after tax NPV at a 6.0% discount factor of approximately $540
        million;
    -   after tax IRR exceeding 20%; (OUR RETURN ON INVESTMENT)
    -   at current spot metal prices, the after tax MPV increases by
        approximately 250 million and the IRR increases by an additional 5%

and then jump to the mining financial basics:
Internal Rate of Return 
We can define Internal Rate of Return by looking at its two parts:
1. Rate of Return is a term used generally to
describe the return we receive on an investment (whether it be a
mining project or putting money into a term deposit).  The rate
of return is basically the amount of income we receive from an
investment, expressed as a percentage of the initial investment. 
So if we bought shares for $100 and received $10 a year in income
from them, our rate of return would be 10% ($10/$100).  It is
important to note the returns can come in the form
of either income, growth in capital value, or
reductions in costs.
2. Internal is added to the start of the rate of
return to show that we are considering our own internal investments
and projects, as opposed to investments our company might make
outside of its own business.  The term internal also tells us
that we are not including interest rates or inflation in our
calculations.
So we can define the Internal Rate of Return of a
project as the rate of growth or income expected to be
generated from an internal project or investment.