Transcript mineral resource - Mercer Island School District

Chapter 14
Mineral Resources
Some Important Elements
Symbols
C carbon
H hydrogen
N nitrogen
O oxygen
P phosphorus
Ca calcium
Fe iron
K potassium
Na sodium
S sulfur
Br bromine
Cl chlorine
Fl fluorine
Al aluminum
Hg mercury
Pb lead
Si silicon
Composition
by weight of
Earth's crust.
Only eight
elements
make up
98.5% of the
crust.
Fig. 3–11
© Brooks/Cole Publishing Company / ITP
Mineral Resources
mineral resource: a naturally occurring
concentration of solid, liquid, or gaseous material
in or on Earth's crust that can be processed into
useful materials at an affordable cost.
• energy resources: coal, oil, natural gas, uranium,
geothermal energy sources;
• metallic mineral resources: iron, copper,
aluminum…;
- ore is a metal–yielding material that can be
economically extracted;
- to be profitable, copper must be concentrated 86
times, gold 1,000 times, & mercury 100,000 times the
crustal average;
- the average 18 karat ring produces 20 tons of waste
• nonmetallic mineral resources: salt, gypsum,
clay, sand, phosphates, water, & soil.
Mineral Deposits Created Through
Igneous Processes
• Hydrothermal deposits: Account for
most metallic mineral deposits (Zn, Cu,
Ag, Au)
• Hydrothermal veins: deposits of
copper, gold, silver
• Some gems: peridotite (olivine) from
basalts; amethyst (quartz)
• Building materials such as Granite
Amethyst
Gold ore
Hydrothermal Deposits
Hydrothermal circulation leaches
metals from rocks, then
concentrates and deposits them
in Volcanogenic Massive Sulfide
deposits (VMS).
Sulfur is often the element
combined with the metal to make
sulfide minerals. Ore minerals
and metals found at VMS’s:
Ore mineral
Sphalerite (ZnS)
Chalcopyrite (CuFeS2)
Galena (PbS)
Metal
zinc
copper
lead
Mineral Deposits Created
Through Metamorphic Processes
• Many gems, including diamonds,
rubies, sapphires, and garnets,
• Building materials such as marble
and slate
Uncut
Diamonds
Garnet
Marble
Mineral Deposits Created
Through Sedimentary Processes
• Aluminum
• Various phosphates and sulfates
• Gypsum (CaSO4)
• Salt
• Uranium
Al reserves
Great Salt Lake, UT
Mineral Resources
The U.S. Geological Survey
(USGS) divides mineral
resources into two broad
categories:
• identified resources: deposits of
a particular mineral resource that
have known location, quantity, &
quality;
• undiscovered resources:
deposits of a particular mineral
resource that are assumed to
exist, based on geologic
knowledge & theory, but for
which specific locations,
quantities, & quality are
unknown.
Al Ore (Bauxite)
Uranium Ore (Carnotite)
Mineral Resources
Reserves are
identified
resources that
can be extracted
economically at
current prices
using current
mining
technology.
Other resources
are identified &
undiscovered
resources not
classified as
reserves.
Fig.14–6
© Brooks/Cole Publishing Company / ITP
Supplies of Mineral Resources
Currently the U.S. imports more than
50% of more than 24 of its most
important non-fuel minerals.
Some non-fuel minerals for which the U.S.
has essentially no reserves:
manganese, cobalt, tantalum, niobium,
platinum, chromium, nickel, aluminum, tin,
antimony, fluorine, asbestos, vanadium;
Mercury
Some non-fuel minerals for which the U.S.
has reserve deficiency:
mercury, silver, tungsten, sulfur, zinc, gold,
potash;
(See Fig.14–11)
Fluorite
Asbestos
Some Mining Vocabulary
• Ore: Economic deposit of metal-yielding material
– Ore mineral: contains desired metal
– Gangue: waste mineral material
• Overburden: rock/soil on top of resource
• Spoil: waste material from overburden
• Beneficiation: separation in a mill of the ore
mineral from the gangue
– Tailings: waste from this process
• Smelting: separates metal from the ore mineral
• Reserves: Identified economic resources
• Grade: the percentage of metal content in an ore
Extracting Mineral Resources
• strip mining is
surface mining in
which the upper layer
is removed to get at
the desired mineral
resource (see
example, left);
• subsurface mining
involves use of drill
holes or tunnels to
extract mineral
resources that are
too deep to be
accessible by surface
mining.
Fig.14–9
© Brooks/Cole Publishing Company / ITP
Bingham Canyon Copper Mine, UT
• The mine provides ~15% of our country’s copper needs
• Other metals: gold, silver, molybdenum, platinum and palladium
• Mining first began in the 1860’s; mine opened in 1906
• Two tons of waste are produced to get one ton of ore, which produces
12 pounds of copper
18 mi SW of
Salt Lake City
Bingham Canyon
Mine Through
Time
It is the
largest manmade hole
on Earth
(over ½ mile
deep). It is
one of only 2
man-made
structures
that can be
seen from
space.
1863
1915
1930
1944
1964
1981
1999
Economics of Mineral Resources
In a free market, rising demand and lowering supply of
a resource should lead to rising costs, a reduction in
demand, a search for substitutes, better/more
efficient technology, etc. But this is not happening
in many developed nations because:
• Mining companies get subsidies such as depletion
allowances, exploration costs for free, public lands
almost free.
• Final cost of goods is only a small fraction of the
cost of mineral resource, so scarcity of resource does
not affect demand.
• Mineral costs are low because mining companies are
not responsible for most environmental costs.
Environmental Effects of Extracting
Mineral Resources
• Scarring of land surface
• Runoff of waste sediment into nearby rivers.
• Acid (H2SO4) seeping into groundwater and
streams, often carrying with them dissolved heavy
metals
• Toxic chemicals used in extraction process leaking
into soils and water: arsenic, cyanide (cyanide
heap leaching p. 353), lead, mercury, cadmium
• Air pollution from smelting plants: SO2, soot,
particulates of arsenic, cadmium, lead, and other
toxic elements found in ores
Environmental Effects of Mineral Extraction
Pollution & degradation of water quality by runoff
of acids & toxic chemicals from surface &
subsurface mining.
Fig.14–14
© Brooks/Cole Publishing Company / ITP
Environmental Effects of Mineral Extraction
Some harmful effects of
mineral extraction,
processing, & use.
Fig.14–13
© Brooks/Cole Publishing Company / ITP\
U.S. 1872 Mining Law
Under an 1872 U.S. mining law (p. 338), any person or
corporation can assume legal ownership of public land
(other than wilderness or park) by filing mining claims
& paying nominal cost for the land (often $6 to $12 per
hectare). 1 hectare = 25.4 acres
• no provision for reclamation of damaged land;
• any country may also file claims and obtain minerals on
U.S. public lands;
• environmentalists want the law to include the following:
- prohibit buying of public land, but allow leasing;
- require environmental impact assessment before leasing;
- set standards for preventing & controlling pollution &
environmental degradation;
- make mining companies legally & financially responsible for
environmental cleanup & restoration.
© Brooks/Cole Publishing Company / ITP
Areas with abandoned
mines
In Washington, most mining
has occurred in the
Cascades, the Kettle Range
and the Selkirks. Most of
the known mines are on
U.S. Forest Service and
Bureau of Land
Management (BLM) turf
Where mines have polluted
water
The U.S. Geological Survey mapped
streams and headwaters tainted with
run off from hard-rock mines, releasing
this version to the public in 1996. At the
request of the EPA, Geological Survey
specialists spent more than two years in
the late 1990s producing a more current
and detailed map based on satellite
data and information from the EPA and
most state governments. Only four
copies of the newer map were
produced. Members of Congress and
state officials, fearing damage to
tourism and development in their states,
have blocked release of the new map.