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APES Test Review

PowerPoint #1: Mineral resources and their extraction

Mineral: solid chemical substance with uniform structure that forms under specifictemperature and pressure conditions.

Usually a compound, but may be composed of a single element (eg gold, silver) Found in rocks, usually with other minerals

Ore: concentrated accumulations of economically valuable minerals Reserve: the estimated amount available for extraction Surface mining Subsurface mining

Examples of Commercially Important Minerals

Gold: Mining for a wedding ring amount of gold results in 20 tons of hazardous miningwaste. Extracted using a process called heap leaching.

Tantalum: Conflict mineral. Deforestation in the Congo. Subsurface mining. In cellphones, MP3s, remote controls, video game consoles.

Diamonds: Conflict mineral. Mostly subsurface mining. Kimberley process has beenlargely ineffective.

Iron: Main ingredient of steel. Huge amount of waste (overburden, spoils), must bemelted at very high temps to isolate (smelting), mostly available as oxides in the crust.

Currently vast amounts. China, Brazil, Australia = biggest producers.

Lead: Always found in compounds. Must be separated from other components in a blastfurnace. The US, Australia, and China are the largest producers. Component of batteries,

construction materials. A neurotoxin. Reserves are predicted to run out in 18-42 years,

depending on recycling rates.

Silicon: By-product of the mining/refining process is carbon monoxide. Used inelectronics, glass, ceramics.

Aluminum: Biggest producers = Australia, Vietnam, Jamaica, Brazil. Found in a mineralcalled bauxite (a compound of Al, O, H). Strip mining is the main form of mining.

Smelting & precipitation needed to isolate. Recycling aluminum takes 5% of the energy it

takes to make new aluminum. Approximately 30% of the aluminum used in the US for

consumer products is recycled

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Surface Mining: General

Existing vegetation is cleared Over burden is removed (top layer of soil and rock). Rock material containing the desired mineral resource is extracted; rock material that is

low in or lacking the desired mineral is left behind as waste ( spoils).

Surface mining is used to extract @90% of the nonfuel mineral resources and @60% ofcoal resources in the U.S.

Open-pit Mining

Machines dig holes and remove ores, sand, gravel, & stone. Toxic groundwater can accumulate at the bottom.

Area Strip Mining

Earth movers strip away overburden, and giant shovels remove mineral deposits. Often leaves highly erodible hills of rubble called spoil banksthat are highly vulnerable

to erosion.

Contour Strip Mining

Used on hilly or mountainous terrain. Unless the land is restored, a wall of dirt is left behind called a highwall. this is highly vulnerable to erosion.

Mountaintop Removal

Explosives and Machinery remove the tops of mountains to expose coal. The resulting waste rock and dirt are dumped into the streams and valleys below.

Subsurface Mining

used to remove coal & various metal ores that are too deep to be extracted by surfacemining

They dig a deep vertical shaft They blast subsurface tunnels & chambers to get to the deposit They use machinery to remove the ore or coal & transport it to the surface

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Subsurface Mining

Advantages Disadvantages

Only way to access someresources

Disturbs less than 1/10th asmuch land as surface mining

Usually produces less wastematerial

Dangerous Collapse of roofs & walls Explosions of dust & natural gas Lung diseases from mining dust Leaves much of the resource in the

ground

Acid Mine Drainage Subsidence

Subsidence

collapse of land above subsurface mines Can cause houses to tilt, crack sewer lines, break gas lines, disrupt groundwater flow

More Mining Impacts

Metal ores are smelted or treated with (potentially toxic) chemicals to extract the desiredmetal.

Example: gold (cyanide, mercury)US Mining laws

US General Mining Law of 1872: any person or corporation can file a mining claim ona piece of federal property and promise to pay $500 to improve it for mineral

development ($120 each subsequent year to maintain the claim)

US Surface Mining Control and Reclamation Act of 1977: requires mining companiesto restore most surface-mined land by grading and replanting it (reclamation)