chapter 15: geology and nonrenewable mineral resources

February 03, 2014

Chapter 15: Geology and Nonrenewable Mineral Resources

What is a nonrenewable resource?

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The Earth: Core, Mantle, CrustTectonic Plates: Lithosphere Surfing

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3 types of plate boundaries:

1. Convergent plate boundary> oceanic-continental: subduction zone and

trench> continental-continental: mountain ranges

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3 types of plate boundaries:

2. divergent plate boundary> oceanic ridge

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3 types of plate boundaries:

3. Transform fault> plates slide past one another> CA San Andreas fault

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Earthquakes, volcanoes, and tsunamis (Read Supplement 11 for more info)

Earthquakes• Richter scale• Recent earthquakes: 2010 Haiti, 2005 Kashmir

(Pakistan)

Volcanoes• found at subduction zones or hot spots

Tsunamis• Giant sea swells• Recent tsunamis: 2004 Indonesia, 2011 Japan

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Tectonic plates recycles Earth's crust over geological time• mineral deposits• evolution

Other processes:• volcanic eruptions play role in forming atmosphere

and climate, rocks and lava become rich soil• Tsunamis leave rich sediment

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External processes (sun and gravity)• Wear down Earth's surface and produce

landforms• Weathering

> Physical/mechanical– Frost wedging

> chemical weathering> biological weathering

http://education.fcps.org/outdoorschoolfcps/frostwedging

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External processes (sun and gravity)• Wear down Earth's surface and produce

landforms• Erosion

> streams> rain> wind> Glaciers> *Human activity

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External processes (sun and gravity)• Wear down Earth's surface and produce

landforms• Mass wasting

> Rockslides> landslides> mudflows

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Resources in the Earth's Crust

Mineral resource: concentration of naturally occurring material in/on the earth's crust that can be • extracted• processed into useful material• affordable cost• Examples: fossil fuels, metallic minerals,

nonmetallic minerals

Ore: Rock that contains enough minerals to mine

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(Pro

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*Increases with new discovery, new technology

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Distribution of mineral resources are not even• US, Canada, Russia, South Africa, and Australia

supply most nonrenewable resources• US, Germany, Russia consume 75% metals• *Economies rely on imports

*Stability of source country can affect supply and practices

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Strategic metal resource: Manganese, cobalt, chromium, platinum

Manganese: Steel production,

Cobalt: Superalloys for jet aircraft engines

Chromium: stainless steel

Platinum: Catalytic converter, emission control

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Rock cycle recycles earth's rocks and concentrates mineral resources.

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Mining, processing, and using mineral resources takes lots of energy, causes land disturbance, soil erosion, and air and water pollution.

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Mining

1. Surface mining

2. Subsurface mining

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Surface Mining: Shallow deposits

• Mechanized equipment removes overburden (soil and rock = spoils)

• 90% nonfuel mineral and rock resources• 60% coal

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Surface Mining

Type of resource and topography determines strategy

• Open-pit mining• Strip-mining (horizontal beds)• Area strip mining (flat terrain)

> Dig trench> Strip mineral> Fill trench with overburden> *Leaves spoil banks

– highly erodible– *Susceptible to chemical weathering and

erosion– *Restoration difficult (no top soil)

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Surface Mining

Type of resource and topography determines strategy

• Contour strip mining (hill or mountains)> terraces> *Coal in Appalachia> highwall: highly erodible bank of soil and rock

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Surface Mining

Type of resource and topography determines strategy

• Mountaintop removal> rock/dirt dumped into streams and rivers> increase flood hazards> toxic wastewater

http://en.wikipedia.org/wiki/File:Martin_County_home.jpg

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Subsurface mining: too deep for surface mining

• Dig vertical shaft + tunnels to reach deposits> disturbs less land> less waste> more dangerous and expensive

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Surface Mining Control and Reclamation Act of 1977

• Requires mining companies to restore most surface mined land

• Unsuccessful, takes a long time• arid areas --> deserts• *coal companies and lobbying

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Mining Impacts• Scarring and disruption of land surface

> $70 billion in cleanup• Subsidence• Pollution

> 5.5 metric tons of mining solid waste for 2 gold wedding rings

> toxins in mining waste (erosion)> acid mine drainage (rain carries sulfuric acid)> mercury, arsenic

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Removing Metals from Ores

Ore ore mineral + gangue

tailings-can contaminate surface water and groundwater

Smelting: roast ore to release metals• Emit air pollutants: sulfur dioxide,

particles

Cyanide heap extraction: Cheap, for gold• Cyanide is toxic• leave behind cyanide-laden water in

leaking holding tanks

http://maharlikafilms.com/blog/

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Supplies of Mineral Resources

Future supply depends on 2 things:• actual or potential supply• rate of use

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Supplies of Mineral Resources

Never truly run out--just becomes too expensive to mine, transport, and process. (Economically depleted)• recycle/reuse• waste less• use less• find a substitute• do without

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Supplies of Mineral Resources

Depletion Time: how long it takes to use up a certain proportion (80%) of the mineral reserve at a given rate of use

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What to do as supplies decrease?1. mine lower-grade ores

> New tech> expensive> process more ore for same amount of mineral> *Water use> environmental impacts: increased land

disruption, waste, pollution> Biomining?

http://www.youtube.com/watch?v=6Arz1G_1QfE

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What to do as supplies decrease?

2. Get minerals from ocean> seawater, sediment, continental shelf,

hydrothermal ore deposits, manganese-rich nodules

> low concentration> Expensive (even minerals in large

concentrations)> Disputes over ownership> manganese nodules cover 25-50% of Pacific

Ocean floor– environmental effects of mining?

http://noc.ac.uk/science-technology/marine-resources/minerals-products/metals-sulphides-nodules

cobalt-rich ferromanganese crust

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Economics of Nonrenewable Minerals• As resource becomes more scarce, prices should

rise> stimulates search for new deposits,

technology• *Government controls supplies and prices

> subsidies keep mineral prices low> help promote economic growth and national

security> What are the effects?

– Companies not motivated to find new technology to be more efficient

– Promotes waste

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Solution? Using mineral resources more sustainably• Materials revolution--find substitues

> silicon, ceramics, plastics> but not a complete substitute> has its own drawbacks (*plastic)

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Solution? Using mineral resources more sustainably• Recycling metals

> lower environmental impact than mining and processing ores

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Solution? Using mineral resources more sustainably• Decrease use and waste

> Ecoindustrial revolution: biomimicry > recycle and reuse> resource exchange webs

– wastes of one manufacturer becomes materials for another

– reduce resource need, pollution– stimualtes technolgoy

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Nanomaterials: what's the deal• Potentially eliminate need for mineral resources

> carbon, oxygen, silicon

• Nanosolar cells• Economy?• Environmental impacts (very small things)

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Test Wednesday on Chapter 14 and Chapter 15.

Chapter 14: Water Resources

Chapter 15: Mineral resources

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Review essay questions:

1. What are the three main strategies to increasing the freshwater supply for people? Choose one and describe the advantages/disadvantages.

2. How have humans contributed to the damage caused by floods?

3. What are mineral resources? What processes make minerals available?

4. Describe three specific negative impacts of mining practices.