Environmental Engineering Reference
In-Depth Information
㻰㼑㼒㼕㼚㼑㼐㼎㼥㼂㻚㻌㻹㻚㻳㼛㼘㼐㼟㼏㼔㼙㼕㼐㼠
㻯㼔㼍㼘㼏㼛㼜㼔㼕㼘㼑㻌㻱㼘㼑㼙㼑㼚㼠㼟
㻿㼕㼐㼑㼞㼛㼜㼔㼕㼘㼑㻌㻱㼘㼑㼙㼑㼚㼠㼟
㻸㼕㼠㼔㼛㼜㼔㼕㼘㼑㻌㻱㼘㼑㼙㼑㼚㼠㼟
,,
Ϩ
㻲㼑
,,,
㻿
㻯㼍
㻯㼡
㻹㼓
㻼㼎
㻭㼘
㻹㼚
㼆㼚
㼀㼕
㻿㼕
㻺㻌㼕
㻿㼚
㻿㼎
㻹㼛
㻭㼓
㻭㼟
㼃
㼂
㻭㼡
㻯㼐
㻿㼑
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㼀㼍
㼀㼑
㻮㼑
㻼㼠
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㻵㼚
㻳㼍
㼘㼛㼓㻯㼘㼍㼞㼗㼑㻺㼡㼙㼎㼑㼞㻔㼜㼜㼙㻕
Fig. 12.5
Classification of metals by Goldschmidt (
1937
)
resources are changing. Here static lifetime is used as an indicator of the future
availability of a specific resource, and is calculated as the quotient of 'Proved re-
serve/Annual usage'. Figure
12.6
shows the changes in static lifetimes of major
metal resources and oil & natural gas. Metal resources other than aluminum, iron
and nickel have varied within a rather narrow range between 20 and 60 years. The
lifetime of crude oil has also been stable at about 40 years, despite claims that it
would not last more than about 20 years at the time of the second oil-shock of 1979.
The production quantity of base metals such as zinc and tin, and noble metals like
gold and silver have generally increased over this period. In particular, their pro-
duction increased drastically (along with steel production) in the resources' bubble
years from 2000 to 2008. Despite this, large shifts have not been seen in their static
lifetime estimates.
There are different hypotheses which can explain this apparent contradiction.
For instance:
1. New mines and oil deposits have been discovered, enabling an increase in
production;
2. The amounts minable from existing mines have been increased by new technolo-
gies; and
3. Information on the reserve estimates have been controlled; for example by major
resource companies and/or mine-rich countries.
