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in turn may be indicative of reserve overproduction in the period between 1997
to 2002. This suggests the possibility of an abrupt decrease in future production.
Nevertheless, lead's pattern might not follow that of other commodities, given that
it is extracted as a byproduct. Consequently the authors advise the reader to take
the model with precaution.
Fig. 13.12 The Hubbert Peak applied to Australian lead reserves
13.3.6 Zinc
Very little interest was shown in zinc until the beginning of the 20th century because
no known method for e
cient Zn separation and recovery had been found. Neither
was there significant global consumption and/or demand. Indeed Zn was previously
seen as a problem within silver and lead mining before a new method of flotation,
first applied in 1905 led to the emergence of the industry.
Prior to the late 1940s the Zn grade of Australian mines fluctuated strongly
between 3 and 17%. Since then, Zn grades have tended to stabilise to around 8.5%
(0.46 toe/t in natural exergy bonus terms).
The Hubbert Peak Model applied to the Australian Zn reserves is shown in
Fig. 13.14. As zinc mining is closely related to the mining of lead and silver, a
similar behaviour is expected. The latest production figures (2000 - 2007) do not
fall under the curve. Despite this, the adjusted curve has a better regression factor
than that of lead and silver at RF = 0:90. The theoretical peak year, assuming
the economic demonstrated reserves R
1898
= 60:4 Mtoe is 2012. Empirical data
(ABARE, 2011), meanwhile, is however far from conclusive and does not point to
any definite peak.
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