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Mineral Resources. GLY 2010 - Summer 2014 Lecture 5. 1. Bingham Canyon Video. Open pit copper mine in Utah. What Is an Ore?. An ore is an economically exploitable deposit. 3. Gangue - aka Mine Tailings.
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Mineral Resources GLY 2010 - Summer 2014 Lecture 5 1
Bingham Canyon Video Open pit copper mine in Utah
What Is an Ore? • An ore is an economically exploitable deposit 3
Gangue - aka Mine Tailings • Gangue is worthless minerals that are associated with the valuable minerals in an ore • Concentrating and smelting removes as much of this gangue as possible 4
Effects of Mining • Mining operations often harm the environment • Today, geologists often find employment cleaning up environmental damage made by mining activities that occurred before environmental regulations were in place.
Right of Way • Phelps Dodge Mine, Morenci, Arizona
Yellow Boy • Iron cations are released by AMD • Acidity is reduced in two ways: • By mixing with water from streams • By reactions with other minerals 10
Yellow Boy Precipitation in a Mountain Stream, San Juan Mountains, Colorado. 11
Polluted Pond Outside the Big 5 Tunnel in Idaho Springs, Colorado 13
"Yellow Boy" Precipitation on the Stream Bed Smothers Aquatic Plants and Animals. 14
Little Dry Fork AMD • Around March 7, 2007, an abandoned mine had a blow out - now acid mine drainage is gushing into Little Dry Fork, just west of Whitesburg, KY.
Ore Formation Processes • Form as a result of natural processes concentrating an element(s) 17
Average Concentration of Valuable Metals in the Crust Aluminum - ~8% Iron - ~5% most Fe and Al is in silicate minerals and is not used as an ore Titanium - 0.44% Nickel - 75 ppm or 0.0075% Zinc - 70 ppm or 0.0070% Copper - 55 ppm 0.0055% Lead - 13 ppm or 0.0013% Silver - 0.07 ppm Gold - 0.004 ppm ppm = parts per million 18
Ore Formation Processes • Hydrothermal and Precipitation • Gravity Settling and Filter Press • Metamorphic fluids • Placer Deposits • Secondary Enrichment 19
Hydrothermal Deposits • Refers to “hot water” • Heat from magma, unusually hot rocks, or metamorphism • May reach 500-700°C • Hot fluids are much better solvents than cold 20
Precipitation • Saturated solution – as much material is dissolved as it can hold • Cooling of saturated solution leads to supersaturation • Dissolved metal comes out of solution as a solid – process is called precipitation • Rain occurs when vapor turns to liquid 21
Disseminated Deposits Bingham Canyon, Utah Upper: Chalcopyrite (Copper ore) Lower: Open pit mine 22
Sixteen to One Gold Mine, California • Entrance to mine 23
Ore Car • A train used to move the ore to the surface 24
Gold in Quartz • A large quartz boulder with a lot of visible gold. Usually, the gold is much finer and hard to see. 25
Gravity Settling and Filter Press • Solids sink to bottom of liquid • Weight squeezes fluid out 26
Metamorphic Fluids • Metamorphism may generate hot fluids • These fluids, with dissolved ions in them, move through rock, altering it 27
Placer Deposition Panning for gold in a placer deposit 28
Aeolian Placers • The "diamond crawl" in a deflation basin, Diamond Area No 1, Namibia • Diamond concentrations were increased by wind erosion 29
Secondary Enrichment • Weathering and erosion often remove soft easily abraded minerals, leaving a concentrated ore behind • Dissolution and reprecipitation can also produce an ore 30
Environmental Problems • Open pits, associated with strip mining, can leave huge scars upon the land • Deep shaft mines can lead to later collapse at the surface • Mining can pollute ground and surface waters, often because of acid mine drainage • Smelting of ores can lead to air pollution 31
Smelter Pollution • Tacoma's ASARCO Smelter, while in operation, was a symbol of both economic growth and environmental pollution. • Special Collections Division, University of Washington Libraries. Photo by Howard Clifford. 32
Washoe Smelter, 1902 • Without environmental regulation, companies were free to dump unfiltered gases from the smelter right into the air • In 1902, this meant 600 tons per day, and increased to 1000 tons/day by 1910 Anaconda, Montana 33
Washoe Smelter • Harmful pollutants, such as arsenic and sulfur, were emitted into the atmosphere 34
One Solution • The Kennecott mine smelter smokestakes were demolished (video)
Non-Metallic Resources • Limestone • Gypsum • Sand and gravel • Clay minerals • Asbestos • Fertilizer • Glass 36