Environmental Engineering Reference
In-Depth Information
Loss of Visual Amenity
Surface mining commonly causes scars on the Earth's surface. While the extent of such
scarring is much less than that associated with rail and road construction, the scars them-
selves tend to be larger and more unsightly, potentially causing a loss of visual amenity.
Visual impacts may diminish public enjoyment, or may impair the character or quality of
a natural landform. Reclamation and eventually mine closure aim to re-instate a stable and
pleasing landform but full rehabilitation of natural vegetation is likely to require several
decades, if it's possible at all.
Loss of visual amenity is most noticeable during construction, when physical change
occurs quickly, and at a scale that few of the local population have ever experienced. In
host regions that have had little past experience with mining, socialization of the size of
mining and associated visual impacts during the consultation phase with the host commu-
nities is important. This can be achieved using photos, i lms taken of similar mines, or 3-D
computer animation of the future mine. However, the best approach is to take representa-
tives of the prospective host community to inspect a mine of similar size and type. This
will help prepare community members for the visible changes that will occur. Unprepared,
an initially supportive community may be overwhelmed, potentially shifting community
support to community opposition. This was a contributing factor to the local opposition
that developed at the Bougainville Copper mine in Papua New Guinea, which eventually
contributed to closure and abandonment of the project.
Reclamation and eventually
mine closure aim to re-instate
a stable and pleasing landform
but full rehabilitation of natural
vegetation is likely to require
several decades, if it's possible
at all.
13.2 MINE WASTES
Mining operations produce a wide range of waste streams, dominated in quantity and
importance by waste rock and tailings ( Figure 13.4 ) . In some cases waste rock and tailings
contribute signii cantly to the total waste output of the host country.
The amount of mine waste produced depends on the type of mineral extracted, as well
as the type and size of the mine ( Figure 13.5 ) . Higher market values allow mining of ore
bodies with lower mineral concentrations, which in turn leads to greater generation of
mine wastes. Gold and silver mines involve the highest levels of waste production in rela-
tion to the amounts of product recovered, with more than 99% of ore extracted ending
up as waste, with waste rock to ore ratios that may be ten to one or greater. By contrast,
mining of iron ore produces much less waste, with approximately 60% of the ore extracted
processed as waste (Da Rosa and Lyon 1997; Sampat 2003). Douglas and Lawson (2000)
estimated the total average material movement per unit of mine product as follows, based
on actual published data and expressed in the form of a multiplier (mine waste equals
multiplier times total mined product, multiplier rounded to the next number):
Mining operations produce a
wide range of waste streams,
dominated in quantity and
importance by waste rock and
tailings.
Bauxite
multiplier of 3
Coal, hard
multiplier of 5
Iron
multiplier of 5
Coal, brown, including lignite
multiplier of 10
Copper
multiplier of 450
Gold
multiplier of 950,000
These multipliers of course relate directly to the average enrichment factors needed to
turn a deposit into a mineable asset (see also Chapter Four).
 
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