Environmental Engineering Reference
In-Depth Information
FIGURE 1.7
A Conceptualized Funding Life-Cycle
of a Mine
Development
Cost
Mining almost always incurs extensive
upfront development costs before
actual ore extraction commences and
the fi nancial and operational responsi-
bilities of mine owners continue after
the mined resource is exhausted.
Source:
Nazari 2000
Debt Service
Profits
Closure
Time
is important to note that pollution problems are not always related to the extracted minerals
and waste, but to altered physical-chemical conditions at the mine site. Also, the area of
interest to miners, that is, the subsurface, can only be sampled sparsely and accordingly is
always subject to a high degree of uncertainty.
Another characteristic of mining is that the location of environmental pressure is con-
fined, in the main, to the area of mineral deposits. This means that mining cannot follow
and utilize existing infrastructure, but must bring infrastructure and other (traditionally
heavy) industry to its location. This results in the creation of secondary pressures or adverse
effects, especially in the case of mine closure. Industrial and other supporting infrastruc-
ture, as well as mine related settlements suddenly become redundant, giving rise to fur-
ther socio-economic pressures. However, the financial and operational responsibilities of
mine owners continue after the mined resource is exhausted ( Figure 1.7 ). The process of
mine closure can last up to two years, while rehabilitation of the mine site can continue for
another four years or more, with the longer periods being particularly applicable to open
Pit mines. Mining company responsibilities may continue even longer when persistent
problems, such as neutralization of acid rock drainage, require long-term management.
The location of environmental
pressure is confi ned, in the main,
to the area of mineral deposits.
Mining and the State of Environment
Economically valuable mineral deposits do not necessarily occur below low value surface
environments, so that mines are sometimes located in or near ecological reserves and pro-
tected areas. They may also be found in conjunction with areas of geologically determined
high natural background values or 'natural pollutants' that are associated with mineral-
ized deposits. This means that often the terrestrial environment is already polluted before
mining commences, which is, in fact, a useful tool for geochemical mineral exploration.
Natural background cannot be remediated to meet limits defined by law. Nevertheless,
the state of the environment over mineral deposits and certain geological formations can
pose regional scale risk to human and ecosystem health. However, actual risks to health
from such pre-existing conditions depend on many factors such as soil organic matter,
metal speciation, pH, etc. Additionally, a given site may already be affected by regionally
 
 
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