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Minerals and Rocks What is a mineral?
naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure What is rock? solid, cohesive, aggregate of one or more minerals Each rock type has a characteristic mixture of minerals What is an Ore? Rock with large concentration of a particular maineral to make it profitable High and low grade ores NON- Metalic Mineral Sand, gravel, limestone Metalic Aluminum, Steel, manganese, cobalt, chromium, Copper, Gold
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Mining: Extract Ore from Ground
Types of Mining: Surface Mining: Scoop ore off surface or earth. cheap. safe for miners. large environmental destruction. Sub-Surface or Underground Mining: Use of shafts to reach deeply buried ores. expensive. hazardous for miners. less environmental damage.
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Video of Pit mining for gold
Surface Mining open pit mining: circular hole in ground, with ramp circling down along sides, allows deeper ore to be reached. Video of Pit mining for gold
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Results of Mining utube
Strip Mining strip-mining: scoop off rock overburden, and then scoop off ore material. Economics of strip mining depend on stripping ratio Large land area can be involved, especially for coal and bauxite. Results of Mining utube
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Bauxite Mine In the Earth's Crust, in every million atoms, around of them are Aluminum, ( ppm1), by weight. This is around 8 % or almost one in every 12 atoms. This places aluminum amongst the world's most abundant elements. Despite being present of Earth in such incredibly vast quantities on Earth, the metal never occurs on it's own in nature. Instead of existing free like Gold and Silver, due to its higher level of reactivity, it is always chemically bonded in compounds when it normally occurs. The most common of these compounds is Bauxite, or Aluminum Ore which contains large quantities of Aluminum Oxide.
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Mountain Top Removal Removing Overburden
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spoils Overburden Coal seem bedrock Appalachian Voices
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Gold in Quartz A large quartz boulder with a lot of visible gold. Usually, the gold is much finer and hard to see.
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Placer Deposition Panning for gold in a placer deposit
Weathering liberates particles of heavy metal containing minerals Minerals and gangue (waste) are transported by water As water velocity decreases, heavy metals sink first, accumulating in protected parts of a stream bed Much of the early gold removed from the Sierra Nevada was found in placer deposits RESISTANT PLACERS Minerals resistant to weathering and erosion may also accumulate in this manner Examples include diamonds, sapphires and rubies (varieties of corundum), and emeralds Photo Source:
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Aeolian Placers The "diamond crawl" in a deflation basin, Diamond Area No 1, Namibia Diamond concentrations were increased by wind erosion
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Non-renewable Mineral Resource Depletion Curves
Source: Miller, G. Tyler, Living In The Environment. (2000) Wadsworth Publishing. New York.
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Environmental Impact of Mining
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Waste water/sludge dams
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Underground Mining A technology originating in antiquity.
A variety of configurations, depending upon conditions
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Acid Mine Drainage AMD results from the oxidation of sulfide minerals at the earth’s surface. This form of chemical weathering generates sulfuric acid, a very powerful acid. The sulfuric acid quickly reacts, dissolving other minerals and often releasing poisonous metal cations into surface waters.
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Environmental Impact of Mining
Scaring the land surface- result spoils banks Soil poor, windblown .. Primary succession slow Toxic wastewater stored in sludge dams. Toxins include slenium, arsenic, and mercury
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Cassiterite tin oxide ore mineral, SnO2. It is generally opaque but is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite has been the chief tin ore throughout ancient history and remains the most important source of tin today TinSoldiers
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Non-renewable Mineral Resource Depletion Curves
Source: Miller, G. Tyler, Living In The Environment. (2000) Wadsworth Publishing. New York.
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US Non-renewable Resource Reserves
Source: Miller, G. Tyler, Living In The Environment. (2000) Wadsworth Publishing. New York.
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Mining is an Economic Activity
The decision to mine (or not to mine) a particular ore deposit depends upon: an analysis of costs, benefits and risks tangible (i.e. dollar profit) intangible (i.e. hopes of stimulating the economy, fears of environmental damage)
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Gradual shift toward surface mining
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Mining around the world Hungary’s disaster China’s rare earth minerals
Minining Law Mining around the world Hungary’s disaster China’s rare earth minerals US rare earth mineral info ad Proposal for New Massive Mine in Romania Goldmining Mining ore Bauxite mining Mountaintop removal
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Mining Issues surface Mine Safety:
In U.S., stringent mining regulations have lead to a reduction in fatalities, both in terms of total deaths per year, deaths per person-hour worked, and deaths per ton mined. surface
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Acid Mine Drainage AMD results from the oxidation of sulfide minerals at the earth’s surface. This form of chemical weathering generates sulfuric acid, a very powerful acid. The sulfuric acid quickly reacts, dissolving other minerals and often releasing poisonous metal cations into surface waters.
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Health Problems collapse of mine. fire (methane, coal dust, etc.).
asphyxiation (methane, carbon monoxide, etc.). pneumoconiosis (from inhaling coal dust). asbestosis (from inhaling asbestos fibers). silicosis (from inhaling silicate dust). heavy metal poisoning (e.g. mercury). radiation exposure (in uranium mining).
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Environmental Damage 4FeS2 + 14H2O = 4Fe(OH)3 + 8H2SO4
Gaping holes in ground (old open pit mines). Piles of mine tailings (non-ore removed from mines). Accidental draining of rivers and lakes. Disruption of ground water flow patterns. Loss of topsoil in strip-mined regions (350 to 2,700 km2 in US alone). Contamination from sulfuric acid (H2SO4) produced through weathering of iron sulfide (FeS2, pyrite) in tailings. 4FeS2 + 14H2O = 4Fe(OH)3 + 8H2SO4 Contamination from heavy metals (e.g. arsenic, mercury) in mine tailings.
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Smelting and Refining: Environmental Problems
Production of huge piles of slag. Emission of CO2, a greenhouse gas, into the atmosphere. Pollution associated with the generation of electricity needed in anode furnaces (especially aluminum). Sulfur dioxide emissions from the refining of sulfide ores are a major source of air pollution. The sulfur dioxide combines with water to produce sulfuric acid. Release of heavy metals (As, Cd, Hg), present in trace quantities in sulfide ores, into the atmosphere.
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Cost Trends copper Cents per pound
Amount of commodities mined per year has generally increased. Commodity prices can take big swings, but average prices during the last century often declined or remained constant. Cents per pound copper Ore grades have all decreased as milling technology has improved
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