How is it determined that a mine has run out of gold?
In: 7119
As mines are operated, the activity of drilling to test for new resources and reserves becomes logistically easier and much less expensive. For example, in an underground mine where the ore body is very well defined and various tunnels and drifts are mined, operators can easily mobilize a drill at depth to punch several holes in a fan-shaped pattern in any vector within 3D space. This is much cheaper than mobilizing a rig at the surface which has to drill through a bunch of overburden and country rock to get to the potential mineral resource (ie, as in a typical early or advanced stage exploration project).
So as an orebody is mined out it’s constantly being drilled at depth to (hopefully) expand the resource and define mineable reserves. Typically operators are able to tell when either the continuity or the grade of the resource is tapering off, and the mine planning and wind down is taken from there.
There is some truth to what others are saying in that sometimes mines run at a loss for some period of time towards the end of its life, but I’d argue that this is generally an unexpected situation for the operator as they would have tested the resource and expected the mill output to generate a profit. As we know, capitalists don’t like to run an operation at a loss for very long, or at all really. In most cases, drilling during operations allows operators to plan for end of life ramp down.
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