To: goldsheet who wrote (68363 ) 4/28/2001 5:57:16 AM From: E. Charters Read Replies (1) | Respond to of 116759 Open pit mines have a hard time highgrading as the pit bottoms are planned well in advance and if they tried to enrich the ore grade by sticking to richer pay streaks, so to speak, all they would do is increase their tails in the mill and decrease the total amount of gold they would take at the face. Much of their cost is fixed capital cost and waste removal costs, not milling throughput so this cutting would not make sense, and would ultimately lower their profits. Their overall long term payback is based on total gold ounces taken to a point where marginal costs at depth start to equal return. If the gold price goes low, it may mean that that marginal point is met earlier, that is all. This may, in some young mines, mean that if the situation would not improve, that they could have to shutdown until gold price improves, or writedown. Pit bottom grade optimization can be tried to an extent to improve things and I am not saying don't try it, just that it is a limited technique. In some cases it would be better to go underground and use extremely high volume techniques as if the grade could be boosted this way it may be just as cheap or cheaper and the equipment could be cheaper. A heap leacher may have some flexibility if he operates from several pits of different grade. He may have to mix to a higher grade to make it and leave some gold behind. Again he faces a long term payback problem here. Underground mines like River Gold may have much more flexibility in mining methods and grade. If they are mature and payback is sustained already or nearly so then they can switch to higher grade or change methods to be more selective. Many methods can be used to upgrade existing stocks including on surface rapid rapid machine rejection techniques of crushed material that was used so successfully in Alaska. Again, they lose gold to do so. Anytime you go for higher grade your loss rate climbs. All mines in Canada that are underground have been rationalizing and cutting back. All have had to go to higher grades to make it and this goes back to 1996. It is a long tradition to adapt with the cost.