Unit 4: Resources

•Intro. to resources

(p. 224-227)

•Mineral Resources (Ch. 12)

•Energy Resources (Ch. 13 & 14)

Resources--General Definition

All things necessary to human life and civilization that have some value to individuals and/or society

What are some resources we’ve already studied?

Renewable: Replaceable on a human time scale

Earth Resources

A) Fuel earth resources

B) Non-fuel earth resources1) Metals (mineral resources)

Al, Cr, Co, Cu, Fe, Pb, Mn, Ni, Sn, Zn, Au, Ag, Pt

2) Non metals (mineral resources)Clays, gypsum, phosphate, salt, sulfur

3) Construction (rock resources)Sand and gravel

Resources & reserves1) Reserves:

The quantity of a given material that has been discovered and can be legally and economically extracted with existing technology.

A conservative estimate

2) Subeconomic reserves (conditional reserves):Deposits already found but cannot be legally or economically

extracted with existing technology

3) Speculative resourcesUndiscovered resources that are expected to be found

Projections about resource availability and price depend on:

• Projections of future supply– Size of reserves– International politics

• Projections of future demand:– Population, standard of living, technology

• Projections of future cost of extraction:– Including environmental costs

Lifetime of Fossil Fuel Reserves

Fuel Resources

Table 12.2

Projected lifetime of reserves (years)(Mineral Commodities Summaries, 1996)

0

50

100

150

200

250

Years

Figure 12.15

Per capitaconsumption

in the US

Fig 12.13: US share of global consumption

Metal Recycling in the US(% of consumption)

0

10

20

30

40

50

60

70

Al Cu Pb Ni Zn Cr Co

1986

1989

1992

1995

Non fuel mineral-rich countries

US: 50% of molybdenum

Australia & New Guinea:50% of aluminum

ore

Congo:50% of cobalt

Cuba:40% of nickel

Chile30% of copper

South Africa50% gold

75% chromium

90 % platinum

50 % manganese

+ diamonds

Non fuel mineral-rich countries

US: 50% of molybdenum

Australia & New Guinea:50% of aluminum

ore

Zaire (Congo):50% of cobalt

Cuba:40% of nickel

Chile30% of copper

South Africa50% gold

75% chromium

90 % platinum

50 % manganese

+ diamonds

WHY ARE NATURAL RESOURCES SO UNEVENLY DISTRIBUTED?

Ore:Rock in which a valuable or useful metal

occurs at a concentration sufficiently high to make it economically worth mining.

Concentration factor:(Conc. in ore)/(conc. in average cont. crust)Ores are unusual rocks with an uneven

worldwide distribution

Examples of Metals obtained from Ores

• Aluminum or Iron – appliances and vehicles

• Metals for conductors or semi-conductors• Gems, gold, and silver – jewelry• Lead from galena• Copper from malachite and azurite• Zinc from sphalerite• Many other metals found in rocks

Cost Factors

• Concentration Factor (CF)• 4 to 25,000 times CF

– highly variable occurrences

• World demand and many market factors• Energy cost• Human/labor cost• Distance to processing or market• Environmental cost - remediation

Types of Mineral Deposits• Igneous Rocks and Magmatic Deposits

– Pegmatite– Kimberlite

• Hydrothermal Ores– hydrothermal

• Relationship to Plate Margins• Sedimentary Deposits

– Banded iron formation– Evaporite

• Other low-temperature ore-forming processes– Placers

• Metamorphic Deposits

Figure 12.6 a

Figure 12.6 b

Mining

Underground mines

Surface mines:A) open pit

Large, 3-D ore body located near the surface

B) strip mines (used mostly for coal)Ore in a strata parallel to the surface

Underground Mines

• Generally hard to see where they are located– Area of disturbance is local

• Miners place the tunnels close to the ore body to cut down on waste

• Once mines are closed they can be sealed with the non-ore rock (waste rock)

• Surface collapse general limited and controllable with modern mine reclamation practices– Old, abandoned, and forgotten mines are still a

problem

Impacts of Mining Activities

• Safety, hazards, and water and air pollution should not be overlooked

• Very stressful to the environment– Must be carefully planned– Must be safe to miners and their neighbors– Must be contained – water and air pollution is a

major problem

Subsurface mining

Collapse of surface mine in Arizona

Subsidence pits, Wyoming

Surface Mines• Quarrying extracts rock to be used either intact

(building blocks or facing stone) or crushed (cement-making and road bed)

• Open-pit – Mine a large ore body located near the surface– Permanent changes to local topography will occur

• Strip mining– Most ores occur in a layer that generally is parallel to

the surface– The ore zone is overlain by vegetation, soil, non-ore

rock that must be removed– Spoils banks are designed to collect the waste rock– Current reclamation law requires that it be return to

the pit and the original soil replaced– Expensive but vital

Largest open pit mine, Utah (>6 billion dollars)

Strip mining Mn in S. Africa

Granite quarry in Vermont

Mineral Processing• Mineral extraction is environmental hazardous

– Ore rock is ground or crushed for extraction– The fine waste material is placed in tailings– The tailings are exposed to wind and weather– Harmful elements such as mercury, arsenic,

cadmium, or uranium can leached out– The surface and subsurface water systems are too

often contaminated– Chemicals used in ore extraction must be controlled

and not just dumped– Smelting ores to extract metals, often produce metal

laden exhaust gas or ash, sulfur oxide and acid rain pollution

Federal Regulations governing mining• National Environmental Policy

Act.• Federal Land Policy and

Management Act • Clean Air Act • Federal Water Pollution Control

Act (Clean Water Act)--Safe Drinking Water Act

• Solid Waste Disposal Act• Comprehensive Environmental

Response, Compensation and Liability Act

• Toxic Substance Control Act

• Endangered Species Act• Migratory Bird Treaty Act• Rivers and Harbors Act, • Mining Law of 1872, • National Historic

Preservation Act, • Law Authorizing Treasury's

Bureau of Alcohol, Tobacco and Firearms to Regulate Sale, Transport and Storage of Explosives, and

• Federal Mine Safety and Health Act.

Modern mine operations

• NMA Website:

Gold production:

• http://www.nma.org/technology/gold_production.asp

Reclamation:

contouring of land• the placement of topsoil or an approved substitute on the

graded area• reseeding with native vegetation, crops and/or trees• years of careful monitoring to assure success

• NMA website: Process of reclaimation– http://www.nma.org/technology/gold_production.asp

ENERGY RESOURCES

• Fossil Fuels (Chapter 13)• Alternative Sources (Chapter 14)

– Nuclear– Solar– Geothermal– Hydropower– Wind– Biomass

Figure 13.1 Society and Energy (shaded = electricity)

Figure 13.2 U.S. energy consumption, 1949-2001

Fossil Fuels

• energy stored in chemical bonds of ancient organic life– Oil– Natural gas– Coal– Oil shale– Tar sand

• When we burn them, we are using that stored energy

Oil and Natural Gas

• Petroleum: complex suite of chemical compounds including oil and natural gas associated with it

• Oil: a variety of heavy liquid hydrocarbon compounds

• Natural Gas: gaseous hydrocarbon compound most commonly methane (CH4)

Source of Oil and Gas Deposits• Organic matter, rich in carbon and hydrogen, accumulate

and are rapidly buried• Rapid burial aids in the decay of the organic material

protecting it from oxygen and biological reactions that would destroy the formation of the hydrocarbons

• Source of the organic material is microscopic life abundant in the seas of the earth– These organisms die and their remains settle to the sea floor– Some natural gases are derived by burial of massive amount of

plant material

Maturation

• The time and history of the formation of the energy deposit are factors– Heat and pressure act to modify the organic

molecules– Large organic molecules (‘heavy’

hydrocarbons) will be broken down into smaller molecules (‘lighter’ hydrocarbons)

• Slow process (10’s-100’s of millions of years)

Figure 13.3 The process of petroleum maturation

Oil and Gas Migration• Liquid and gaseous hydrocarbon will migrate

out of the rocks in which they formed

• hydrocarbon will pool in economically usable deposits

• Reservoir rocks for hydrocarbon are overlain by impermeable caps that trap the migration of the hydrocarbons, otherwise, oil and gas may keep rising to the earth’s surface

Fig. 13.4 Types of petroleum traps

Supply and Demand for Oil

• Recent consumption rates have rapidly increased

• Proven remaining reserves are estimated at 1 trillion barrels– Unevenly distributed around the world– Most oil is consumed by the highly

industrialized countries• The United States alone consumes over 25% of

the oil used worldwide• Kuwait has 10% share of world oil reserves

Coal

• Provides about 20% of U.S. energy supply– More than 50% of U.S. electric power

generation

• Formation of Coal Deposits– Coal is formed from remains of land plants,

not from marine organisms– Swamp settings ideal with abundant trees and

leaves– Requires anaerobic conditions to convert the

fallen trees and dead leaves into coal

Figure 13.15

World Coal Reserves (anthracote + bituminous)

Figure 13.18

Limitations on Coal Use• Coal is not clean

– To mine– To burn– To handle

• Coal can be converted to a liquid fuel by liquefaction

• Coal can be converted to a gas by gasification

Environmental Impacts of Coal Use• Produces abundant carbon dioxide when burned

– Carbon dioxide is a greenhouse gas

• Liberates sulfur as sulfur dioxide into atmosphere upon burning– Acid Rain: sulfur dioxide is toxic and complexes with atmospheric

water to produce sulfuric acid

• Ash is liberated from coal upon burning– Ash is as much as 20% of the volume of coal– Often contains toxic metal such as selenium and uranium

• Coal mining poses further problems: safety and environmental issues

Coal-Mining Hazards and Environmental Impacts

• Underground mining of coal is dangerous and expensive– Mines can collapse– Miners contract black lung disease from coal dust or cancer from

radon gas– Explosion occur from pockets of natural gas

• Strip mining exposes the coal to the weather– Rain water and air comes in contact with sulfur in the coal beds

or waste rock – produces sulfuric acid

Pyrite + water + oxygen = sulfuric acid + hydrated iron oxide

• Coal mine reclamation is expensive and time consuming