Geology Reference
In-Depth Information
Table 13.1 Results summary for the principal Australian minerals
B
,
ktoe/yr
MtMe B
,
ktoe
Mineral
t
Peak R/P,
yrs
% R
Loss
Au
1859 - 2007
2007 24
71
7.6E-03
101,437 1,941
Cu
1844 - 2007
2026 68
27
72.2
64,228
2,717
Ni
1967 - 2007
2039 129
16
3.1
17,597
746
Ag
1884 - 2007
2009 24
64
9.9E-02
23,012
584
Pb
1859 - 2007
1994 35
63
32.3
36,458
685
Zn
1897 - 2007
2012 30
52
57.0
31,237
930
Fe
1907 - 2007
2031 62
21
22,041
2,148,610 95,484
Coal
1913 - 2008
2047 140
15
-
-
-
Oil
1964 - 2009
1996 20
68
-
-
-
N:Gas
1961 - 2009
2029 79
18
-
-
-
TOTAL
2,422,578 103,086
The resources to production data, informs society of the estimated years left
until depletion. The most depleted commodities are in ascending order: oil, silver,
gold, zinc and lead, with R/P ratios of less than 35 years. They are followed by
iron, copper, natural gas, nickel and finally coal, with R/P ratios of 62, 68, 79, 129
and 140 years, respectively. Of course these figures are only approximative, since
they depend strongly on production rates and reserves. The latter might increase as
new discoveries are found, or as technology or price dictates — with the extraction
of lower-grade deposits.
Although the quantity extracted of all commodities in terms of mass cannot be
combined (gold and silver are extracted at rates of tonnes per year, whereas other
metals at kt/yr), the order of magnitude in terms of exergy costs (B
) is similar for
all commodities and its sum provides valuable information. The exergy replacement
cost obtained for all metals in Australia (Table 13.1) is equal to 2,423 Mtoe. The
degradation velocity of the metals is on average, since the beginning of the 21st
century, 103 Mtoe/yr. This means that if one were to replace the metals extracted
throughout Australia's entire mining history, with current available technology, one
would require around 5 times the oil reserves of that country (510 Gtoe (BP, 2010)).
Moreover, Australia is year on year, through metal extraction, degrading on average
the equivalent exergy of 4 times its primary oil production. Of all metals, iron is
responsible for 92% of the exergy cost consumption, due to the great quantity
produced.
Figures 13.23 to 13.25 show the natural exergy bonus (B
) associated with the
total consumption for all metals considered, from 1844 to 2007. In the first period
illustrated in Fig. 13.23, the extraction of gold, copper and silver contribute to most
of the natural bonus lost, although lead acquires a relevant role from the end of the
19th century. In the second period, 1907 to 1963 (Fig. 13.24), the extraction of iron
represents a major natural bonus exhaustion, although the metals mentioned pre-
viously, together with zinc also contribute significantly. From 1950 to the present,
iron clearly dominates the non-fuel mineral bonus depletion in Australia.
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