Download MINERAL RESOURCES

GEOLOGY and MINERAL
RESOURCES
Geologic Processes: Structure of
the Earth
Fig. 4-7 p. 60
Major Rock Groups
• Igneous
– Formed from a melt (molten rock)
– Plutonic (intrusive):slow cooling and crystallization
– Volcanic (extrusion): quick cooling at the surface
• Sedimentary
– Formed at the Earth’s surface
• Metamorphic
– Changed by pressure, temperature and fluids.
3
Fig. 2.9
MAGMA
IGNEOUS
Crystallization
MAGMA
5
IGNEOUS
Plutonic
Crystallization
MAGMA
6
Volcanic
IGNEOUS
Plutonic
Crystallization
MAGMA
7
Weathering
Volcanic
IGNEOUS
Plutonic
Crystallization
Uplift
MAGMA
8
External Earth Processes
Erosion (wind, water, gravity)
Mechanical weathering
Frost wedging
Chemical weathering (precipitation &
Moisture)
Biological weathering (root wedging,
borrowing)
Weathering
SEDIMENT
Volcanic
IGNEOUS
Plutonic
Crystallization
Uplift
MAGMA
10
Weathering
SEDIMENT
Erosion
Transport
Deposition
Volcanic
IGNEOUS
SEDIMENTARY
Plutonic
Crystallization
Uplift
MAGMA
11
Weathering
SEDIMENT
Erosion
Transport
Deposition
Volcanic
IGNEOUS
SEDIMENTARY
Plutonic
Crystallization
Uplift
MAGMA
12
Weathering
SEDIMENT
Erosion
Transport
Deposition
Volcanic
IGNEOUS
SEDIMENTARY
Plutonic
Increased P&T
METAMORPHIC
Crystallization
Burial
Uplift
MAGMA
13
Weathering
SEDIMENT
Erosion
Transport
Volcanic
Can you see
IGNEOUS
any shortcuts?
Deposition
SEDIMENTARY
Plutonic
Increased P&T
METAMORPHIC
Crystallization
Melting
Uplift
Burial
MAGMA
14
Weathering
SEDIMENT
Erosion
Transport
Deposition
Volcanic
IGNEOUS
SEDIMENTARY
Plutonic
Increased P&T
METAMORPHIC
Crystallization
Melting
Uplift
Burial
MAGMA
15
In Conclusion…
• The rock cycle
demonstrates the
relationships among the
three major rock groups
• It is powered by the
interior heat of the Earth
• The energy from the sun
• It involves processes on
the Earth’s surface as
well as the Earth’s
interior.
Features of the Crust and Upper
Mantle
Plate Tectonics
Divergent boundary
Convergent boundary
Subduction zone
Transform fault
Fig. 16-5 p. 336
Divergent Boundaries
• Spreading ridges
– As plates move apart new material is erupted to
fill the gap
Iceland: An example of continental rifting
• Iceland has a divergent
plate boundary running
through its middle
Convergent Boundaries
• There are three styles of convergent
plate boundaries
– Continent-continent collision
– Continent-oceanic crust collision
– Ocean-ocean collision
Continent-Continent Collision
• Forms mountains, e.g. European Alps, Himalayas
Himalayas
Continent-Oceanic Crust Collision
• Called SUBDUCTION
• Area is called the subduction zone
Transform Boundaries
• Where plates slide past each other
Above: View of the San Andreas
transform fault
Earth’s Major Tectonic Plates
Natural Hazards: Earthquakes
 Features
 Magnitude
 Aftershocks
 Primary effects
 Secondary effects
Expected Earthquake Damage
No damage expected
Minimal damage
Canada
Moderate damage
Severe damage
United States
Fig. 16-7 p. 337
Natural Hazards: Volcanic Eruptions
extinct
volcanoes
central
vent
magma
conduit
magma
reservoir
Solid
lithosphere
Upwelling
magma
Partially molten
asthenosphere
Volcanic Eruptions
• Pyroclastic Flow – cloud of ash and debris
– Travel at hundreds of mph
– Hundreds of degrees
Volcanic Eruptions
• Lahar – mud flows which are very destructive
to landscape
Volcanic Eruptions
•
•
•
•
•
http://www.youtube.
com/watch?v=UK-hvgP2uY
“Ash” emitted includes small stones
Very dense
Chokes life
Blots out sunlight
Causes wide range temperature drops
Tsunami
• “Harbor Wave”
Nonrenewable Resource
• Resource that exists in a fixed amount in various
places in the Earth’s crust and has the potential
for renewal only by geological, physical and
chemical processes taking place over hundreds
of millions of years.
• Mineral Resources – naturally occurring,
inorganic solid in or on the earth’s crust that can
be extracted and processed into useful materials
at an affordable cost.
Nonrenewable Mineral Resources
Metallic ores – (Fe, Cu, Al)
Non-metallic – (salt, gypsum,
clay, sand, PO4)
Energy resources – (coal,
radioactive isoptopes, oil,
natural gas) – typically not
mineral resources
Nonrenewable Mineral Resources:
USGS Categories
 Identified –
know location,
quality and quantity
 Undiscovered inferred
 Reserves known location,
affordable extraction
 Other -identified/
undiscovered but NOT reserved
Finding Nonrenewable Mineral Resources
Satellite and air imagery
Radiation detectors
Magnetometers
Gravity differences
Seismic surveys
Chemical analyses
Extracting Nonrenewable Mineral
Resources:
Open-pit (surface mining)
Dredging (surface mining)
Area strip (surface mining)
Contour strip (surface mining)
Room-and-pillar (subsurface mining)
Longwall (subsurface mining)
Open Pit Mining (surface)
• Machines remove mineral resource.
Dredging (surface)
• Dig underwater mineral deposits
Area Strip Mining (surface)
• Strip mining in flat landscape areas.
Contour Strip Mining (surface)
• Creation of “terraces” along contour elevations
where overburden is removed and a high wall is
created which is very erodable.
Mountaintop Removal
• Dragline cuts the top of the mountain off
and dumps it into the surrounding valley.
Room and Pillar (subsurface)
• This method creates shafts dug below the
surface that are then blasted with dynamite
to create tunnels. The ore/coal can then be
hauled to the surface.
Room & Pillar Method
Room and pillar mining is
commonly done in flat or
gently dipping bedded
ores. Pillars are left in
place in a regular pattern
while the rooms are
mined out. In many room
and pillar mines, the
pillars are taken out,
starting at the farthest
point from the mine
haulage exit, retreating,
and letting the roof come
down upon the floor.
Room and pillar methods
are well adapted to
mechanization, and are
used in deposits such as
coal, potash, phosphate,
salt, oil, shale, and
bedded uranium ores.
Longwall (subsurface)
• Dig a narrow tunnel supported by removable
pillars. The benefit is that no tunnels are left
behind to collapse once abandoned.
Subsurface vs. Surface Mining
• Subsurface mining is less environmentally
destructive than surface mining BUT
Subsurface mining is more dangerous to workers.
Walls collapse, explosions from gas, inhalation of
mining dust leads to “black lung”
U.S. 1872 Mining Law
• Encourages mining in the USA for gold, silver, lead,
copper, uranium, and hard rock minerals.
• People OR Corporations can patent public land by:
a. Declaring it has valuable minerals
b. Spending $500 to improve land for mineral
development
c. Filing a claim for the land
d. Pay US Government $2-5/acre!
MINERALS NEVER NEED TO BE EXTRACTED
Can sell land to extraction companies for millions of
dollars (usually foreign companies) who pay no royalties
to US Government.
Colorado Case Study
• Canadian Company bought a site for a few thousand
dollars.
• They spent 1 million dollars developing the site, removed
98 million dollars worth of gold.
• Acid mine drainage leached into the Alamusa River.
• Company declared bankruptcy and abandoned the site
leaving the EPA Superfund to pay for clean up (=
taxpayer money)
• Costs = 40,000/day to contain toxic waste
• Also contaminates irrigation water (no way to clean up)
USA 1872 Mining Law Continued
• If public land is designated as valuable
wilderness area, the government can buy
back the land (our tax $) at “market value”.
• Any lands mined do not have to be
reclaimed. They can be left in highly
erodable states with leaching toxins into
air, water, and soil.
Mining Company Practices
•
1.
2.
3.
4.
5.
6.
Companies will usually:
Mine land
Abandon the land
File for bankruptcy
Leave taxpayers with cleanup bill (33-72 billion dollars
per year!
Superfund sites (Super funds that the EPA designates
to be used for hazardous waste cleanup)
If groundwater becomes contaminated, it can’t be
cleaned up and there is no way of estimated the cost
to humans!
Should the mining law of 1872 be
changed?
•
1.
2.
3.
4.
5.
6.
7.
Environmentalists propose amendments to the law:
Lease land for 20 years instead of buying it.
Conduct full NEPA Environmental Assessment of impacts before mining
begins.
Set strict standards for controlling pollution and protecting environment
from toxins and erosion.
Company should post environmental insurance bond to cover estimated
environmental damage and clean up costs in the future.
Companies should pay rent to cover costs for government monitoring of
lands.
12.5% royalty should be paid to government on gross sales. Mining
companies claim that charging royalties and forcing them to clean up
their mess will not make it economically feasible to mine in USA
anymore. This will lead to a decrease in jobs for Americans.
Environmentalists claim mining companies will still make profits, just not
as much!
Make mining companies legally and financially responsible for clean up.
Surface Mining Control and
Reclamation Act
Established
1977
Mine lands must be restored to
pre-mining conditions
Taxes on mining companies to
restore pre-1977 sites
Limited success
Environmental Effects of Mining Mineral
Resources
Disruption of land surface
Subsidence
Erosion of solid mining waste
Acid mine drainage
Air pollution
Storage and leakage of liquid mining
waste
Environmental Degradation From
Processing of Minerals
• Processing includes transportation,
purification, and manufacturing of minerals
• Smelting impacts air, water, and soil
“What goes up must come back down”
Smelting
desired ore
Gange (waste)
Beneficiation – separation of
additional ore from gange
Ore
Tailings (toxic metals)
Environmental Impacts
• Air and noise pollution
– Dust created by mining and
loading/unloading
– Machine causes noise pollution and damage
nearby structures
Environmental Impacts
• Water Contamination
– Water picks up and dissolves toxic
substances (arsenic)
– Sulfur and water – diluted sulfuric acid
• Acid Mine Drainage - AMD
Environmental Impacts
• “Mountain Dew Teeth”
Environmental Impacts
• Displacement of Wildlife
–
–
–
–
Stripping of plant life
Animals leave area
New ecosystem created after
Destroy river and sea bottoms
Environmental Impacts
• Erosion and Sedimentation
– Sediments find way into streams
– Choke stream life
– Degrades water quality
Environmental Impacts
• Soil Degradation
– Deeper soil layers added to top
– Decreases richness of original
soil
• Subsidence (sink holes)
– Sinking of regions of ground
with no horizontal movement
http://www.theblaze.com/stories/2013/03/0
1/man-goes-missing-in-florida-whenbedroom-falls-into-sinkhole/
Environmental Impacts
• Underground Mine Fires
– Last decades and even centuries
– Australian fire – 2,000 Years!!!!!
– Gas and smoke emitted
Smelting Copper
• Cu
Sox soot (SO2) + As + Cd + Pb
Scrubbers and
electrostatic
precipitators are
expensive
technology that help
to remove the
harmful substances
before being
released into the
atmosphere.
Environmental Degradation From
End-Use
•
Transportation to user, final use, and
discarding after use.
(a) Fossil fuels are burned during transportation of
end product.
(b) Product must be discarded in:
1. landfill where metals corrode and pollute
land and water.
2. Recycle and reuse (In USA, most goes to
landfill, but recycling of solid waste is
improving each year.
Environmental Effects of Mining Mineral
Resources
Fig. 16-14 p. 344
More Environmental Impacts of
Nonrenewable Mineral Resources
Surface mining
Subsurface mining
Overburden
Room and pillar
Spoil
Longwall
Open-pit
Dredging
Strip mining
Refer to Figs. 15-4 and
15-5, p. 341 and 342
Processing Mineral Resources
Ore mineral – what is wanted
Gangue – waste around ore
Tailings - leftover
Smelting – process to remove
Refer to Fig. 16-15 p. 344
Supplies of Non-Renewable
Resources
• Dependent on:
(a) actual or potential supplies
(b) rate of use
Minerals become economically depleted when the
cost of extraction is greater that the profit.
What de we do? We have choices
(a) refuse, reduce, reuse, recycle
(b) find substitute
Depletion of Mineral Resources
Depletion Time – the
time it takes to use up
a certain proportion
(80%) of the reserves
of a mineral at a given
rate.
Common Projection Rate
– “Reserve to Production
Ratio” = the number of
years that proven
reserves of a particular
non-renewable resource
will last at a current
production rate.
Economics of Mineral Resources
• Free Market when supply is greater than
demand = cheap costs to consumers.
Definition: a market in which supply and demand are
unregulated except by the country's competition policy,
and rights in physical and intellectual property are
upheld.
In a free market there are:
(a)Fulfillment: the process of responding to customer
inquiries, orders, or sales promotion offers.
(b)Future: a contract to deliver a commodity at a future
date.
(c)Futures market: a market for buying and selling
securities, commodities, or currencies that tend to
fluctuate in price over a period of time.
Why are items made of Zn, Pb, Hg, Fe, and
Al so cheap, if their depletion times are
nearing?
•
•
1.
2.
3.
4.
Fe/Al – 100 years in world reserves.
Hg/Zn/Pb – 20 years in world reserves.
Subsidies – to promote economic growth and national
security. Is there really a free market?
Harmful environmental costs of mining and processing
are not included in their market price. NO TRUE
COSTING!
Ore grades have been lowered. Example 1900 Cu
penny – 5% by weight, now 0.5% by weight. Ask
yourself…are reserve to ration production numbers
real?
As technology improves we learn more about where
more minerals may be on Earth and don’t have to
impart tremendous damage to landforms during
exploration activities.
Global Non-Fuel Minerals
• Mostly in the USA, Canada, Australia, South Africa, and
the Republics of the former Soviet Union.
• Western Europe – depends mostly on minerals from
Africa.
• USA imports 24 of the 42 most important non-fuel
minerals.
• Concerns: manganese, cobalt, platinum, and chromium
– USA has little or no reserves and we get them from
unstable African nations.
• USA uses these minerals for autos, airplanes, engines,
satellites, and sophisticated weapons!