Mineral Formation & Extraction

Ch. 14

We can make some minerals in the earth’s crust into useful products, but extracting and using these resources can disturb the land, erode soils,

produce large amounts of solid waste, and pollute the air, water, and soil.

How are minerals used?

Mineral UseSilver Photography, chemistry,

electronic products, jewelry, coins

Titanium Jet engines, powder for white paint pigment, paper, rubber

Limestone ConstructionHalite Diet (salt), sodium

hydroxide, ceramic glazesGraphite Dry lubricant, brake linings,

pencils

Mineral

• Element/compound of elements naturally occurring in the crust

• EX. Steel = Iron & Carbon Bronze = Tin & Copper Copper Sulfur

Where are minerals found?

• Rocks – combinations of minerals• Ore/ore body – concentrated

mineral chunk that can be mined for profit

Ore/Ore Body

High Grade• Large amounts of

particular mineral

Low Grade• Small Amounts of

minerals

Classification of Minerals

• Mineral resources include: –Metallic–Non-metallic– Energy Resources

Non-renewable

Classification

Metallic• Iron, Copper,

Aluminum– Malleable– Lustrous– conductors

Nonmetallic• Sand• Stone• Phosphates• Salts

Classification

• Energy Resources– Coal–Oil–Natural Gas– Uranium

How do minerals form? Name Description

Magma Concentration As magma cools, separates into layers based on differences in densities (iron on bottom, silicates on top)]

Fe, Cu, Ni, Cr

Hydrothermal Processes - Ore deposits - Black smokers

Heated groundwater seeps through cracks/fissures dissolving minerals in rocks which get transported with water

Au, Ag, Pb, Zn

How do minerals form?

Magma

Black smoker

Sulfidedeposit

White crab

Tube worms

Whitesmoker

Hydrothermal ore also occur when upwelling magma solidifies into black smokers

Especially rich in Cu, Pb, Zn, Ag, Au

How do minerals form? Name Description

Sedimentation Weathering breaks down parent rock into particles which are transported by water and deposited into beds

Fe, MN, P, S, Cu

Evaporation Dissolved material accumulates in inland lakes/seas with no/small outlets – evaporation occurs leaving behind mineral deposits.

NaCl, borax, gypsum salts

How are minerals discovered and extracted?

1. Prospecting2. Mining/Extractions3. Smelting/Processing

1. Prospecting

Finding places where ores occur.

Is it profitable to mine? $$$$

Prospecting Tools

• Satellite Imagery• Aerial Sensors (magnetometers)• Gravity Difference (gravimeter)• Core Sampling• Seismic Surveys• Chemical analysis of water &

plants

2. Mining Extracting

Surface• Less $• Open Pit• Strip Mining• Safer for miners• Environmental

Damage

Subsurface• More $$$• Shaft• Slope• Hazardous for

miners• Less Environmental

Damage

Surface Mining

• Mechanized equipment strips overburden of soil & rock

• Discards it as waste called spoils• In US: – 90% of nonfuel mineral & rock

resources– 60% of coal by weight

Surface Mining Types

Open-pit mining

Open-pit mining

Surface Mining Types

Surface Mining Types *

Area Strip Mining

Surface Mining Types

Surface Mining Types

Contour Strip Mining

Undisturbed land

Overburden

PitBench

Spoil banks

Surface Mining Types

Mountaintop Removal

Mountaintop Coal Mining in West Virginia

Fig. 14-17, p. 359

Ecological Restoration of a Mining Site in Indonesia

Fig. 14-18, p. 360

Subsurface Mining

Used to remove coal and various metal ores that are too deep to be extracted by surface mining

Subsurface Mining

• Shaft• Slope–Disturbs less

land– Produces less

waste–More

dangerous–More expensive

3. Smelting/Processing *

Heat to extract pure ore from impurities

Surface mining

Metal ore Separation of ore from gangue

Smelting Melting metal

Conversion to product

Discarding of product

Recycling

Life Cycle of a Metal Resource

Environmental Implications

Remember: Mining is an economical activity.

Environmental Implications

Decisions to mine depend on: - Financial risk- Potential profit- Risk of environmental damage- Economic viability of mineralNOT A SIMPLE ISSUE!

Natural Capital Degradation

Extracting, Processing, and Using Nonrenewable Mineral and Energy

ResourcesSteps Environmental Effects

Mining Disturbed land; mining accidents; health hazards; mine waste dumping; oil spills and blowouts; noise; ugliness; heat

Exploration, extraction

Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat

Transportation, purification, manufacturing

Use Noise; ugliness; thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat

Transportation or transmission to individual user, eventual use, and discarding

Environmental Implications

Environmental Effects of Extracting (Mining) and

Processing

Fig. 15-7 p. 344

• Land damage of surface and vegetation

• Water use threatens supplies of groundwater

• Water quality damage: heavy metals are leached resulting in acid mine drainage

• Gangue: worthless material that surrounds, or is mixed with minerals in an ore deposit.

Environmental Effects of Mining/Extraction

Environmental Effects of Mining/Extraction

• Tailings: mine waste from impurities in ore can be toxic

• Air pollution from smelting plants

• Energy requirements of equipment, processing, refining, labor intensive, etc.

• Subsidence or collapse

Environmental Effects of Using a Mineral Resource

a) Disruption of land surface 500,000 mines

b) Subsidencec) Erosion of solid mining wasted) Acid mine drainage

H2SO4

e) Air pollution Mining produces more toxic emissions than

any other industry

f) Storage and leakage of liquid mining waste

Legislation

• Surface Mining Control and Reclamation Act of 1977– Requires mining companies to

restore most surface-mined land so it can be used for the same purpose as it was before it was mined

– Levied a tax on mining companies to restore land that was disturbed by surface mining before the law was passed.

Legislation

• General Mining Act of 1872– allowed individuals/corporations to

stake claims to mine metals on federal lands at $2.50 to $5 per acre

– cheap land for developing the western US by patenting

– law contains no provision for env. protection or reclamation of topsoil/vegetation/habitat

Fun Facts

EX. In 1995 ASARCA (US company) paid $1,745 for land that produced $2.9 billion worth of minerals (Cu/Ag)

EX. 1993 Manville Corp. paid $10,000 for land in Montana that contains about $32 billion of palladium and platinum

Of the ~1200 Superfund sites (the nations worst toxic waste sites) about 52 are mines.