February 03, 2014

Chapter 15: Geology and Nonrenewable Mineral Resources

What is a nonrenewable resource?

February 03, 2014

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

February 03, 2014

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

February 03, 2014

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

fitab

le)

*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

February 03, 2014

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/

February 03, 2014

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

February 03, 2014

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

February 03, 2014

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

> carbon, oxygen, silicon

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

February 03, 2014

Test Wednesday on Chapter 14 and Chapter 15.

Chapter 14: Water Resources

Chapter 15: Mineral resources

February 03, 2014

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.