Environmental Engineering Reference
In-Depth Information
FIGURE 4.3
Enrichment Factors for Selected Metals
100,000
Mercury
Each mineral or metal has its own
enrichment factor, which represents
a balance between the price of the
material and its average abundance in
the Earth's crust. If the price of a par-
ticular metal falls, it requires an even
higher enrichment factor for the metal
to be economically extractable.
Tungsten
10,000
Tin
Silver
Gold
Lead
Molybdenum
1,000
Platinum
Zinc
Copper
100
10
Iron
Aluminium
1
4.2 EXPLORATION - FROM REVIEWING DATA TO
TAKING BULK SAMPLES
Minerals cannot be considered as wealth unless known, and the discovery of mineral
wealth comes with great difi culty. One Canadian research study relates exploration efforts
to the number of actual mines which result (Roscoe 1971). From around 1,000 mineral
prospects identii ed, only 100 are drilled for reconnaissance. From these, only 10 progress
to intensive exploration drilling. From these 10, eventually only one mineral deposit will
become a mine (
Figure 4.4
)
. Modern exploration, loosely dei ned as all activities that even-
tually lead to the discovery of an ore deposit, may have altered these ratios, but not much.
Signii cant economic deposits are difi cult to i nd. They have to be discovered.
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