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Mining
I. Mineral Resources
A. A mineral resource is a concentration of
naturally occurring material from the earth’s
crust that can be extracted and processed into
useful products and raw materials at an
affordable cost.
B. We know how to find and extract over 100
minerals from the earth’s crust, including fossil
fuels, metallic minerals (Al, Fe, Cu) and
nonmetallic minerals (sand, gravel, limestone).
All mineral resources are considered nonrenewable resources.
I. Mineral Resources
C. An ore is rock that contains a large enough
concentration of a particular mineral – often a
metal – to make it profitable for mining and
processing.
1. High-grade ore: Large amount of mineral
2. Low-grade ore: Small amount of mineral
I. Mineral Resources
D. What do we use these metallic mineral
resources for?
1. Aluminum – packaging, cans, motor vehicles,
airplanes
2. Iron – critical component of steel, used for
buildings and motor vehicles
3. Manganese, cobalt, molybdenum, and
chromium are all widely used to strengthen
alloys of steel
I. Mineral Resources
4. Copper – Used for electrical wiring and
plumbing
5. Platinum – Used in electrical equipment and
in catalytic converters in cars
6. Gold – Used in electrical equipment, coins,
chemical reaction catalysts, and jewelry
I. Mineral Resources
E. What are non-metallic minerals used for? The
most widely used non-metallic minerals are
sand and gravel.
1. Sand – used to make glass, bricks, and
concrete
2. Gravel – roads and concrete
3. Limestone – Used for road rock, concrete,
cement, and building materials
4. Phosphate salts – In inorganic fertilizers and
in some detergents
II. Removing Mineral Deposits
A. After suitable mineral deposits are located,
several different mining techniques are used
to remove them, depending on their location
and type.
B. Surface mining – Shallow deposits
C. Subsurface mining – Deep deposits
II. Removing Mineral Deposits
D. Steps in surface mining:
1. Anything growing on the land (forest, ect) is
first cleared away. Then, gigantic mechanical
equipment strips away the overburden- the
dirt and rock about the mineral deposit. The
waste dirt and rock are called spoils.
Sometimes minerals can be dredged from
streams – the wastes are then called tailings.
II. Removing Mineral Deposits
2. Four types of mining processes can then be
used, depending on the land topography –
a) Open pit mining- big pits are dug and ores
are removed
World’s largest open
pit mine –
Kennecott
Copper Mine (in
Utah).
Considered the
world’s largest
human
excavation.
Has been open since
1906, 2.5 miles
across, .75 miles
deep.
On US. National
Register of
Historic Places
II. Removing Mineral Deposits
b) Strip mining – for mineral deposits close to
the earth’s surface that lay in horizontal beds.
Strips or trenches are dug, and as a trench is
depleted and new trenches are dug, the
overburden is placed in the trenches.
II. Removing Mineral Deposits
c) Contour strip mining – Used mostly to mine
coal on hill-sides. A huge power shovel cuts
terraces into the side of a hill. If the land is
not restored afterward, a highly erodible bank
of soil and rock called a highwall is left over.
II. Removing Mineral Deposits
d) Mountain-top removal – Used predominately
in the Appalachian Mountain area of the US.
Explosives and large power shovels remove
the tops of mountains, exposing seams of
coal, and overburden is dumped in valleys,
which often completely changes or ruins
streams, wetlands, and rivers.
Mountain-Top Mining Clip:
Steven Colbert discusses with
leading Mining Scientist, Dr. Palmer
1/18/10
• http://www.colbertnation.com/the-colbertreport-videos/261997/january-18-2010/coalcomfort---margaret-palmer
II. Removing Mineral Deposits
E. Subsurface mining – Used to remove coal and
metal ores too deep in to be extracted by
surface mining.
F. Miners dig a shaft, blast open subsurface
tunnels to reach the deposit, and remove coal
or ore and transport it to the surface.
III. Environmental Consequences of
Mining
A. Scaring and disruption of the land surface is
one major issue with mining. Spoil banks,
empty pits, and tailing piles are all left behind
from mines. Any regrowth of vegetation is
slow because there is no topsoil.
III. Environmental Consequences of
Mining
B. Mountain top mining in Appalachia has
buried 1,200 miles of streams and rivers, and
470 of its largest mountains have disappeared,
leaving behind barren land and huge pits.
III. Environmental Consequences of
Mining
C. Since 1980, millions of miners have streamed
into tropical forests and other tropical areas in
search of gold. These small scale miners use
destructive techniques such as digging large
pits, dredging sediments from rivers, and
hydraulic mining- a technique, outlawed in the
U.S., that uses water cannons to wash entire
hillsides into collection boxes for removal of
gold.
III. Environmental Consequences of
Mining
D. Surface mining in tropical areas destroys or
degrades biodiversity when forests are cleared
and mining wastes pollute near-by streams
and rivers.
III. Environmental Consequences of
Mining
E. Surface mining sites
can be cleaned up
and restored but it is
costly. The U.S.
department of the
interior estimates
that at least 500,000
surface mined sites
exist in the U.S.
F. Subsurface mining disturbs much less land
then surface mining, and produces less waste
material. However, it leaves more ore in the
ground and is much more dangerous for
miners. Subsidence (sinking of the ground) is
a problem with surface mining.
III. Environmental Consequences of
Mining
G. Mining causes major pollution to water and
air. For example, acid mine drainage occurs
when rainwater seeping through a mine or
mine waste pile carries sulfuric acid, produced
when aerobic bacteria act on iron sulfide
minerals in spoils, polluting streams and
groundwater.
H. Additionally, chemicals such as sulfuric acid,
mercury, and arsenic are used to extract
minerals from ore, and huge amounts of water
are used to flush these toxic chemicals
through ore piles. This contaminated water
gets into streams and groundwater.
I. For example, highly toxic cyanide salts are
used to extract gold from ore.
J. According to the EPA, mining has polluted 40%
of watersheds in the western U.S.