it isn't a dream, just prudent managementmining the lower grades when prices rise is not a new idea. it's a standard strategy, and works well in any of several scenarios.
basically mining companies face three possibilities when prices rise.
a) prices have risen and will subsequently fall.
b) prices have risen and will stabilize (level off)
c) prices have risen and will continue to rise.
mining the lower grades when the prices rise enough to do so at a profit works well for all three scenarios.
a) the mine life is extended and the company continues to operate at a profit. leaving the high grade to help the company survive during harder times.
b) the mine life is extended and the high grade s are available for use when prices are high
c) mine life is extended and it sets up a "best case" scenario of using the highest grades at eleveter (and climbing) prices.
there is no scenario in which using the low grades when they can be utilised economically has a negative effect. it is a win-win-win proposition.