Environmental Engineering Reference
In-Depth Information
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Fig. 12.6
Changes in static lifetime of major metal resources and oil & natural gas
Today, the amount of a reserve which is minable has become one of the most im-
portant pieces of information for resource companies, and it is thus very difficult
to collect reliable data. It is thus rather difficult to verify the above hypotheses, but
the following suggestion can be made: The resource price usually increases with an
increase in its consumption. It can thus be easily recognized that the costs available
for mining, beneficiation and transportation can also be raised when prices of re-
source products are increased. Thus, lower grade ores (which may have been called
soils or sands/rocks beforehand) will become utilizable as new resources. Further-
more, the criterion for mine closure will also change as larger amounts of resources
will be capable of being economically produced from the same mine. These likely
tendencies are closely related to the above hypotheses 1) and 2). Taking account
of the above, the amount of the resource which is minable can be expected to vary
depending on the resource price; and this in turn influences the static lifetime of the
resource.
Despite the trend for some metal resources, the static lifetimes of aluminum, iron
and nickel have decreased year by year (Fig.
12.6
). Especially, that of iron greatly
decreased from about a 400 year estimate in 1980 to about 150 years by 2005, fol-
lowed by a further decrease to about 80 years in 2010's estimates. Such a change
is very different to that for copper or zinc, and does not correspond to the changes
in global steel production shown in Fig.
12.3
. Global steel production in 1965 and
1975 were about 500 and 600 million t respectively, and increased only ~20 %; in
contrast, the static lifetime of iron ore resource decreased in the same period from
