3. Surfase mine
Fig. 1, above shows an illustration of a Open Pit Surface Mine. The
definition of a open pit mine is "an excavation or cut made at the surface of
the ground for the purpose of extracting ore and which is open to the
surface for the duration of the mine’s life." To expose and mine the ore, it is
generally necessary to excavate and relocate large quantities of waste rock.
The main objective in any commercial mining operation is the exploitation
of the mineral deposit at the lowest possible cost with a view of
maximizing profits. The selection of physical design parameters and the
scheduling of the ore and waste extraction program are complex
engineering decisions of enormous economic significance. The planning of
an open pit mine is, therefore, basically an exercise in economics,
constrained by certain geologic and mining engineering aspects.
A bench may be defined as a ledge that forms a single level of operation
above which mineral or waste materials are mined back to a bench face.
The mineral or waste is removed in successive layers, each of which is a
bench. Several benches may be in operation simultaneously in different
parts of, and at different elevations in the open pit mine.
