Geology and Nonrenewable Minerals Chapter 14

Core Case Study: Environmental Effects of Gold Mining  Gold producers South Africa Australia United States Canada  Gold can be chemically dissolved by cyanide the only way to extract gold found in small quantities  Cyanide heap leaching Extremely toxic to birds and mammals 2000: Collapse of a dam retaining a cyanide leach pond Impact on organisms and the environment

3 The most significant risk from use of cyanide solutions in gold mining is possible leaching into soil and groundwater. There exists the potential for catastrophic cyanide spills that could inundate an ecosystem with toxic levels of cyanide

Gold Mine with Cyanide Leach Piles and Ponds in South Dakota, U.S.

14-1 The Earth Is a Dynamic Planet  What is geology? Study of dynamic processes occurring on the earth’s surface and interior  Three major concentric zones of the earth Core Mantle Including the asthenosphere Crust Continental crust Oceanic crust: 71% of crust

Earth’s Internal Structure: Compositional Layers  Crust: Continental crust (20-70 km) Oceanic crust (~6 km)  Mantle Upper mantle Lower mantle (660km km)  Core Outer core (liquid) Inner core

Internal Geological processes  Internal Geological Processes are generated by heat from the earth’s interior, typically build up the earth’s surface in the form of continental and oceanic crust, including mountains and volcanoes.  They are influenced by gravity. 7

The Earth Beneath Your Feet Is Moving  Convection cells, or currents  Tectonic Plates  Lithosphere

10 Lithosphere  Lithosphere is divided into plates (about 13 major plates and several smaller ones).  Consists of rigid, brittle crust and uppermost mantle.

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The Earth Beneath Your Feet Is Moving  Three types of boundaries between plates Divergent plates Seafloor Spreading Places where plates are coming apart Magma Mid-Oceanic ridge Convergent plates Places where plates crash or crunch together Subduction Subduction zone Trench Transform fault; e.g., San Andreas fault

Oceanic Divergent Boundary

Continental Divergent Boundary

Ocean – Ocean Convergent Boundaries

Ocean-Continent Boundaries

17 Continent – Continent Boundaries

Transform Boundaries  Most fracture zones connect segments of mid-ocean ridges  Areas of different water depth on each side of fracture zone  Shallow earthquakes occur on transforms between sections of mid-ocean ridge

San Andreas fault

21 Hot Spots  Columns of hot material rising through mantle (plumes).  Source seems to be core-mantle boundary area - low velocity zones in lower mantle  Hot spot fixed in position underneath moving lithospheric plates

Some Parts of the Earth’s Surface Build Up and Some Wear Down  Internal geologic processes Generally build up the earth’s surface Generated from the heat from the earth’s interio r influenced by gravity  External geologic processes Driven directly or indirectly by energy from the sun ( flowing water and wind) and influenced by gravity Weathering Physical, Chemical, and Biological Erosion Wind Flowing water Human activities Glaciers

Volcanoes Release Molten Rock from the Earth’s Interior  Volcano Fissure Magma Lava  1980: Eruption of Mount St. Helens  1991: Eruption of Mount Pinatubo  Benefits of volcanic activi ty Scenery and fertile soils

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Yellowstone Caldera

28 Eruption of Mount Saint Helens, May 18, 1980  The eruption of Mount Saint Helens was the most destructive in the history of the United States  Mount Saint Helens is located in southwest Washington in the Cascade Range, a mountain range dominated by periodically active volcanic peaksIn  Images include pre-eruption activity and post- eruption effects such as the blast area, mud flows, ash fall, and altered terrain  s.html s.html

Mount St. Helens pre-eruption

Mount Pinatubo before 1991

1991 eruption of Mount Pinatubo

39 Volcanic winter

Earthquakes Are Geological Rock-and- Roll Events  Earthquake Seismic waves Vibration of earth produced by rapid release of energy Vibration of earth produced by rapid release of energy Focus source source Epicenter point on the Earth 's surface that is directly above the hypocenter or focus Magnitude- measure of ground motion Amplitude- size of the seismic wave

Japan

Earthquakes Are Geological Rock-and- Roll Events  Richter scale  Each unit has amplitude 10 X greater than the next smaller unit. Insignificant: <4.0 Minor: 4.0–4.9 Damaging: 5.0–5.9 Destructive: 6.0–6.9 Major: 7.0–7.9 Great: > Japan 2011

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Earthquakes on the Ocean Floor Can Cause Huge Waves Called Tsunamis  Tsunami, tidal wave Giant wave caused by underwater earthquake  Detection of tsunamis  December 2004: Indian Ocean tsunami Magnitude of 9.15 Role of coral reefs and mangrove forests in reducing death toll

14-2 There Are Three Major Types of Rocks  Earth’s crust Composed of minerals and rocks  Three broad classes of rocks, based on formation 1.Sedimentary Sandstone Shale Dolomite Limestone Lignite Bituminous coal

There Are Three Major Types of Rocks 2.Igneous Granite Lava rock 3.Metamorphic Anthracite Slate Marble

Sedimentary Rocks Rock formed by the piling of material over time Sediment is compressed, heated and chemically changed over long period of time Examples: Sandstone, Shale, Gypsum, Limestone, Chalk

Igneous Rocks Rock formed by cooling and crystallization of magma If the cooling occurs at the surface, it is called extrusive igneous If the cooling occurs in the Earth, it is called intrusive igneous Extrusive igneous usually cools fairly rapidly and therefore has smaller crystals than intrusive Examples: Granite, Basalt, Quartz, Mica, Feldspar, Obsidian

Metamorphic rocks- Igneous or sedimentary rock subjected to tremendous pressure and heat

The Earth’s Rocks Are Recycled Very Slowly  Rock cycle  Slowest of the earth’s cyclic processes

52 Igneous Rock Granite, Pumice, Basalt Sedimentary Rock Shale, Sandstone, Limestone Metamorphic Rock Slate, Quartzite, Marble Magma (Molten Rock) Weathering Erosion Transport Deposition Heat, Pressure Heat, Pressure Heat, Pressure Heat, Pressure Rock Cycle

14-3 We Use a Variety of Nonrenewable Mineral Resources  Mineral resource Fossil fuels- coal Metallic minerals- aluminum, iron and copper Nonmetallic minerals- sand, gravel and limestone  Ore - contains high enough concentration of a particular mineral to make it profitable for mining and processing High-grade ore Low-grade ore

Mineral Use Has Advantages and Disadvantages  Advantages of the processes of mining and converting minerals into useful products Generates income, and provides local, state and national revenues from taxes, fees and royalties Provides employment for a variety of jobs  Disadvantages Takes an enormous amount of energy to process It disturbs the land, erode soil, produce solid waste and pollutes the air, water and soil

The Life Cycle of a Metal Resource

There Are Several Ways to Remove Mineral Deposits  Surface mining Shallow deposits removed  Subsurface mining Deep deposits removed  Type of surface mining used depends on Resource Local topography

57 Open Pit Mine - Surface Mining

58 The worlds biggest hole is located in Russia. The giant hole is actually a diamond mine in Eastern Siberia near the town Mirna.It is 525 m deep, and 1,25 km.in the diameter.

59 T his loader is one of the biggest in the world: length:13,36 m width: 7,78 m height: 6,65 m This giant machine appears just a small point in the next image.

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62 The suction above the hole resulted in several helicopter crashes, so all flight above the hole now is prohibited.

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65 A view from a satellite.

66 Dredging – Surface mining

67 Area Strip Mining – Surface mining

68 Contour Strip Mining – Surface Mining

69 Underground Coal Mine – Subsurface mining Ventilation shaft Shaft Main shaft Lift cage Pumps Coal seams

70 Room-and-pillar- Subsurface mining

71 Longwall Mining of Coal – Subsurface mining

Mountain top Removal

73 Mine Subsidence

74 Environmental Effects of Mining Mineral Resources Acid Mine drainage Damaged more than 12,000 miles of streams in the US

75 More Environmental Impacts of Nonrenewable Mineral Resources Surface mining Subsurface mining  Overburden  Spoil  Open-pit  Dredging  Strip mining  Room and pillar  Longwall Refer to Figs and 15-5, p. 341 and 342

76 Processing Mineral Resources  Ore mineral- contains the desired metal  Gangue- waste material  Tailings- piles of waste from removing the gauge from the ore.  Tailings- piles of waste from removing the gauge from the ore.  Smelting – is used to separate the metal from the other elements in the ore mineral. (produces enormous about of pollutants)  Smelting – is used to separate the metal from the other elements in the ore mineral. (produces enormous about of pollutants)

77 Aluminum is mined from Bauxite

78 Mining Bauxite to make aluminum  Five tons of this Bauxite is required to produce one ton of aluminum. Significant energy is required for this process, including mining, ore crushing and transporting of the ore to the refinery. Once at the alumina processing refinery, energy is needed for grinding the ore and heating and dissolving aluminum oxide. The raw alumina is then washed, filtered and cooled, heated again to dry, then transported to ports for shipping.

79 Recycling aluminum cans it’s easy!!!!  Ninety-five percent of the energy required to turn bauxite ore into aluminum is saved when recycling aluminum instead of processing it from raw materials, meaning about seven kWh are saved per pound recycled.  The amount of energy saved to produce an aluminum can run a television for three hours.  The amount of energy saved by recycling aluminum cans in the United States per year is equivalent to approximately 15 million barrels of oil, which at today’s prices equates to $1.1 billion.

14-4 Mineral Resources Are Distributed Unevenly  Most of the nonrenewable mineral resources supplied by United States Canada Russia South Africa Australia

Strategic Metals, such as Manganese, chromium and platinum, the largest reserves are found in South Africa 81 Manganese mine in Kalahari Desert

Supplies of Nonrenewable Mineral Resources Can Be Economically Depleted  Future supply depends on Actual or potential supply of the mineral Rate at which it is used  When it becomes economically depleted Recycle or reuse existing supplies Waste less Use less Find a substitute Do without

Case Study: The U.S. General Mining Law of 1872  Encouraged mineral exploration and mining of hard-rock minerals on U.S. public lands  Developed to encourage settling the West (1800s)  Until 1995, land could be bought for 1872 prices  Companies must pay for clean-up now

84 The General Mining Law of 1872  It was designed to encourage mineral exploration and the mining of hardrock minerals (such as gold, silver, copper, zinc, nickel, and uranium) on US public lands and to help develop the then sparsely populated West.  Person or Corp can assume ownership of any public land not classified as wilderness or park by patenting it.  Spend 500 bucks to improve the land for mineral development, file a claim, pay 2-5 bucks an acre!  Canadian Corp bought land in Nevada for $10,000 that had billion worth of gold!

85 The General Mining Law of 1872 continued  No reclamation clause  Abandoned mines are major source of Acid Mine Damage  In 1992 the law was modified to require mining companies to post bonds to cover 100% of the estimated cleanup cost in case of bankruptcy.

14-5 There Are Many Ways to Use Mineral Resources More Sustainability  How can we decrease our use and waste of mineral resources? Do not waste mineral resources Recycle and reuse 60-80% of mineral resources Full- cost pricing Reduce mine subsidies Increase subsidies for recycling Slow population growth