1. Chapter 23
Minerals
and Mining

2. This lecture will help you understand:
Mineral resources
Mining methods
Impacts of mining
Reclamation and mining policy
Sustainable use of minerals

3. Central Case Study: Mining for … Cell Phones?
Cell phones and other high-tech products contain tantalum
Coltan: columbite + tantalum
Since 1998, the war in the
Democratic Republic of the Congo has killed 5 million
Soldiers controlled mining operations and forced farmers and others to work, while taking most of the ore
People entered national parks, killing wildlife and clearing rainforests, causing ecological havoc
Profits from coltan sales financed the war
Most tantalum from the Congo goes to China

4. The rock cycle 4 4

5. Earth’s mineral resources
We mine and process mineral resources for countless products

6. We use mined materials extensively
We don’t notice how many mined resources we use
The average American uses 37,000 lb of new minerals and fuels every year
This level of consumption shows the potential for recycling and reuse
A child born in 2009 will use 2.9 million lb of mined resources over its life

7. We obtain minerals by mining
We obtain minerals through the process of mining
Mining: in the broad sense, it is the extraction of any nonrenewable resource of economic interest
Fossil fuels, groundwater, and minerals
Because minerals occur in low concentrations, concentrated sources must be found before mining is begun

8. We extract minerals from ores
Metal: an element that is lustrous, opaque, and malleable and can conduct heat and electricity
Ore: a mineral or grouping of minerals from which we extract metals
Economically valuable metals from ore include:
Copper, iron, lead, gold, aluminum
Tantalite ore is mined, processed into tantalum, and used in electronic devices

9. We process metals after mining ore
Most minerals must be processed after mining
After the ore is mined, rock is crushed, and the metals are isolated by chemical or physical means
The material is processed to purify the metal
Alloy: a metal is mixed, melted, or fused with another metal or nonmetal substance
Steel is an alloy of iron and carbon
Smelting: heating ore beyond its melting point, then combining it with other metals or chemicals
Modifies the strength, malleability, etc., of metals

10. Environmental costs of processing minerals
Water- and energy-intensive
Chemical reactions and heating to extract metals from ores emit air pollution and toxic wastes
Tailings: ore left over after metals have been extracted
Pollute soil and water
Contain heavy metals or chemicals (cyanide, sulfuric acid)
Surface impoundments: store slurries of tailings
Accidents release pollutants into the environment

11. We also mine nonmetallic minerals and fuels
Sand and gravel provides fill and construction materials
Phosphates provide fertilizer
Salt, limestone
“Blood diamonds” are mined and sold to fund, prolong, and intensify wars in Angola and other areas
Poor people are exploited for mine labor
Substances are mined for fuel
Uranium is used in nuclear power
Coal, petroleum, natural gas, oil sands, oil shale, methane hydrate are not minerals (they are organic)

12. Economically important mineral resources

13. Mining methods and their impacts
Mining provides jobs and money for communities
It provides raw materials for products we use
Mining has environmental and social costs
Large amounts of material are removed during mining, disturbing lots of land
Different mining methods are used to extract minerals
The method used depends on economic efficiency

14. Strip mining removes surface soil and rock
Strip mining: removal of layers of soil and rock to expose the resource just below the surface
Overburden: soil and rock that is removed by heavy machinery
After extraction, each strip is refilled with the overburden
For coal, oil sands, sand, gravel
Causes severe environmental impacts
Strip mining destroys natural communities over large areas and triggers erosion

15. Subsurface mining: underground work
Accesses deep pockets of a mineral through tunnels and shafts up to 2.5 miles deep
Zinc, lead, nickel, tin, gold, diamonds, phosphate, salt, coal
The most dangerous form of mining
Dynamite blasts, collapsed tunnels
Toxic fumes and coal dust
Collapsed tunnels cause sinkholes

16. Acid drainage
Acid drainage: sulfide in newly exposed rock reacts with oxygen and rainwater
Produces sulfuric acid
Sulfuric acid leaches toxic materials from rock
Flows into streams, killing fish and other organisms
Pollutes groundwater used for drinking and irrigation
Although acid drainage is natural, mining greatly accelerates it by exposing many new rock surfaces at once

17. Open pit mining creates immense holes
Used with evenly distributed minerals
Terraced, so men and machines can move about
Copper, iron, gold, diamonds, coal
Quarries: open pits for clay, gravel, sand, stone (limestone, granite, marble, slate)
Huge amounts of rock are removed to get small amounts of minerals
Habitat loss, aesthetic degradation, acid drainage
Abandoned pits fill with water
Acid drainage forms if sulfur is present

18. The world’s largest open pit mine
This Utah mine is 2.5 mi across and 0.75 mi deep; almost half a million tons of ore and rock are removed each day

19. Placer mining uses running water
Using running water, miners sift through material in riverbeds
Used for gold, gems
Debris washes into streams
They become uninhabitable for wildlife
Disturbs stream banks
Causes erosion
Harms plant communities

20. Mountaintop removal reshapes ridges
Entire mountaintops are blasted off
“Valley filling”: dumping rock and debris into valleys
For coal in the Appalachian Mountains of the eastern U.S.
Degrades and destroys vast areas
Pollutes streams; deforests areas; causes erosion, mudslides, flash floods, biodiversity loss
An area the size of Delaware has already been removed

21. Mountaintop removal is devastating
Mine blasting cracks foundations and walls
Floods and rock slides affect properties
Coal dust and contaminated water cause illness
Lung cancer, heart and kidney disease, pulmonary disorders, hypertension, death
The poor people of Appalachia suffer while we benefit from coal-produced electricity
Critics argue that valley filling violates the Clean Water Act
In 2010, the EPA introduced rules to limit damage

22. Solution mining dissolves resources
Solution mining (in-situ recovery): resources in a deep deposit are dissolved in a liquid and sucked out
Water, acid, or other liquids are injected into holes
Used for salt, lithium, boron, bromine, magnesium, potash, copper, uranium
Less environmental impact than other methods
Less surface area is disturbed
Acids, heavy metals, uranium can accidentally leak or leach out of rocks and contaminate groundwater

23. Ocean mining We extract minerals (e.g., magnesium) from seawater
Minerals are dredged from the ocean floor
Manganese nodules: small, ball-shaped ores scattered across the ocean floor
These reserves may exceed all terrestrial reserves
Logistical difficulties in mining have kept extractions limited, so far

24. Restoring mined sites only partly works
Governments in developed countries require companies to reclaim (restore) surface-mined sites
Reclamation aims to bring a site to a condition similar to its pre-mining condition
Remove structures, replace overburden, replant vegetation
The U.S. Surface Mining Control and Reclamation Act (1977) mandates restoration
Companies must post bonds to cover restoration costs

25. Restoration of mined sites
Even on restored sites, impacts may be severe and long-lasting
Complex communities are simplified
Forests, wetlands, etc., are replaced by grasses
Essential symbioses are eliminated and often not restored
Water can be reclaimed
Moderate the pH
Remove heavy metals

26. The General Mining Act of 1872
Encourages metal and mineral mining on federal land
Any citizen or company can stake a claim on, or buy (for $5 per acre), any public land open to mining
The public gets no payment for any minerals found
Supporters say it encourages a domestic industry that is risky and requires investment to locate vital resources
Critics say it gives valuable public land basically free to private interests
People have developed the land (e.g., for condominiums) that have nothing to do with mining
Efforts to amend the act have failed in Congress

27. Minerals are nonrenewable and scarce
Many minerals are rare and could become unavailable
Once known reserves are mined, minerals will be gone
For example, indium, used in LCD screens, might last only 32 more years
Gallium (for solar power) and platinum (fuel cells) are also scarce
Estimating how long a reserve will last is hard
New discoveries, technologies, consumption patterns, and recycling affect mineral supplies
As minerals become scarcer, prices rise

28. Years remaining for selected minerals
Time periods can increase if more reserves are found or decrease if consumption increases

29. We can use minerals sustainably
Recycling minerals addresses:
Finite supplies
Environmental damage
35% of metals were recycled in 2009 from U.S. solid waste
35% of our copper comes from recycles sources
Recycling decreases energy use
It also lowers greenhouse gas emissions
Aluminum from raw sources uses 20 times more energy than from recycled sources

30. We can recycle metals from e-waste
Electronic waste (e-waste) from computers, printers, cell phones, etc., is rapidly rising
Recycling keeps hazardous wastes out of landfills while conserving mineral resources
Cell phones can be refurbished and resold in developing countries
Or their parts can be dismantled or refurbished
Today, only 10% of cell phones are recycled
Reduces pressure on ecosystems

31. Conclusion
Geologic processes shape Earth’s terrain and form the foundation for living systems
We depend on minerals and metals to make our products
Mineral resources are mined by various methods
Contribute to material wealth
But cause extensive environmental damage (habitat loss, acid drainage, etc.)
Restoration and regulations help minimize the environmental and social impacts of mining
Recycling and sustainable use prolong mineral resources 31 31