1. Chapter 15 Geology, Minerals, and Mining
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. This presentation will help you understand:
Mineral resources and their contributions to society
Mining methods
Social and environmental impacts of mining
Sustainable use of mineral resources

3. Minerals and mining
We extract raw minerals from beneath our planet’s surface
Turn them into products we use everyday
Rock and resources from the lithosphere contribute to our economies and lives
Rock = a solid aggregation of minerals
Mineral = a naturally occurring solid chemical element or inorganic compound
It has a crystal structure, specific chemical composition, and distinct physical properties
Minerals are nonrenewable, so we need to be aware of their finite and decreasing supplies

4. ECONOMIC GEOLOGY & MINERALOGY
Economic mineralogy is the study of minerals that are valuable for manufacturing and trade.
Public policy in the U.S. has encouraged mining on public lands as a way of boosting the economy and utilizing natural resources.

5. Most economic minerals are metal ores (ores are minerals with high concentrations of metals).
Metals are elements that easily give up an electron and thus have a positive charge (cations).
Metals consumed in the greatest quantity by world industry (metric tons annually) are:
Iron (740 million)
Aluminum (40 million)
Manganese (22.4 million)
Copper (8 million)
Chromium (8 million)
Nickel (0.7 million)

7. Nonmetal Mineral Resources
Sand and gravel production for road and building construction make up the greatest volume and dollar value of all nonmetal mineral resources. This includes brick and concrete construction, paving, sandblasting and glass production.
Evaporites include halite (rock salt), gypsum, potash
Sulfur deposits are mined mainly for sulfuric acid production (industry, car batteries, some medicinal products).
Limestone is used to make concrete and building stone. Pulverized, it is used to neutralize acidic soil.
Soils

8. Strategic metals and minerals are ones that a country uses but cannot produce itself
Wealthy industrial nations often stockpile strategic resources, especially metals.
Of the 80 industrial metals and minerals, between one-third and one-half are considered strategic resources.

10. Minerals are everywhere in our products

11. ENVIRONMENTAL EFFECTS OF RESOURCE EXTRACTION
Geologic resource extraction involves the physical processes of mining and the physical or chemical processes of separating minerals, metals, and other geologic resources from ores or other materials.
Ore - a rock in which a valuable or useful metal occurs at a concentration high enough to make mining it economically attractive

12. We obtain minerals by mining
We obtain minerals through the process of mining
Mining = in the broad sense, it is the extraction of any resource that is nonrenewable
We mine minerals, fossil fuels, and groundwater
Mining = in relation to minerals, it is the systematic removal of rock, soil, or other material to remove the minerals of economic interest
Because minerals occur in low concentrations, concentrated sources must be found before mining

13. 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 include copper, iron, lead, gold, aluminum
Tantalite ore is mined, processed into tantalum, and used in electronic devices

14. We process metals after mining ore
Most minerals must be processed after mining
After mining the ore, 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

15. Processing minerals has costs
Processing minerals has environmental costs
Most methods are water- and energy-intensive
Chemical reactions and heating to extract metals from ores emit air pollution
Tailings = ore left over after metals have been extracted
Pollutes soil and water
They may contain heavy metals or acids (cyanide, sulfuric acid)
Water evaporates from tailings ponds, which may leach pollutants into the environment

16. We also mine nonmetallic minerals and fuels
Nonmetallic minerals include sand, gravel, phosphates, limestone, and gemstones
$7 billion/year of sand and gravel are mined in the U.S.
Phosphates provide fertilizer
“Blood diamonds” are mined and sold to fund, prolong, and intensify wars in Angola and other areas
Substances are mined for fuel
Uranium for nuclear power
Coal, petroleum, natural gas are not minerals (they are organic), but they are also extracted from the Earth

17. Economically useful mineral resources

18. Mining and Processing Extraction and separation
Ore = rock with high concentration of valuable or useful metal
Must be economically feasible
1% Cu ore
0.0001% Au ore

19. Mining Underground, tunnel mining is very dangerous due to:
Gas
Inhaling Particulate Matter
Tunnel Collapse
Placer mining
Strip-mining or open-pit mining
Tailings - surface waste deposits
Groundwater contamination
Spoil banks - acid and sediment runoff

20. Implications of Resource Extraction
Mining
Placer Mining - Hydraulically washing out metals deposited in streambed gravel.
Destroys streambeds and fills water with suspended solids.
Strip, Open Pit or Mountain Removal Mining
Large scars on land surface.
Tailings
Toxic runoff
Surface Mining Control and Reclamation Act (SMCLRA) (1977) requires better restoration of strip-mined lands, especially if the mined land is classified as prime farmland.
Difficult and expensive.
Often more than $10, per hectare.
50% of US coal is strip mined.

21. Mining methods and their impacts
People in developing nations suffer war and exploitation because of the developed world’s appetite for minerals
In 2009, raw materials from mining gave $57 billion to the U.S. economy
After processing, minerals contributed $454 billion
28,000 Americans were directly employed for mining
Large amounts of material are removed during mining
Disturbing lots of land
Different mining methods are used to extract minerals
Economics determines which method to use

22. Strip mining removes surface soil and rock
Strip mining = layers of soil and rock are removed to expose the resource
Overburden = overlying soil and rock that is removed by heavy machinery
After extraction, each strip is refilled with the overburden
Used for coal, oil sands, sand, gravel
Destroys natural communities over large areas and triggers erosion
Acid drainage = sulfide minerals form sulfuric acid and flow into waterways

23. Strip mining destroys the environment
Strip mining removes soil
Discolored water is a sign of acid drainage

24. Environmental Effects of Mining

26. A mining method: subsurface mining
Accesses deep pockets of a mineral through tunnels and shafts
The deepest mines are 2.5 mi
Zinc, lead, nickel, tin, gold, diamonds, phosphate, salt, coal
The most dangerous form of mining
Dynamite blasts, collapsed tunnels
Toxic fumes and coal dust
Acid drainage, polluted groundwater
Sinkholes damage roads, homes, etc.

27. A mining method: open pit mining
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 toxic water

28. One open pit mine
One 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

29. A mining method: placer mining
Using running water, miners sift through material in riverbeds
Coltan miners, California’s Gold Rush of 1849
Used for gold, gems
Debris washed into streams makes them uninhabitable for wildlife
Disturbs stream banks, causes erosion
Harms riparian plant communities

30. A mining method: mountaintop removal
Entire mountaintops are blasted off
The waste is dumped into valleys
For coal in the Appalachian Mountains of the eastern U.S.
Economically efficient
“Valley filling” = dumping rock and debris into valleys
Degrades and destroys vast areas
Pollutes streams, deforests areas, erosion, mudslides, flash floods
An area the size of Delaware has already been removed

31. Mountaintop removal is socially devastating
Mine blasting cracks foundations and walls
Floods and rock slides affect properties
Overloaded coal trucks speed down rural roads
Coal dust and contaminated water cause illness
Local politicians do not help
High-efficiency mining reduces the need for workers

32. Heap-leach extraction is when large piles of crushed ore are sprayed with a alkaline cyanide solution that percolates through the pile to dissolve gold. The effluent is left behind in ponds.

33. A mining method: solution mining
Solution mining (in-situ recovery) = resources in a deep deposit are dissolved in a liquid and siphoned out
Salts, lithium, boron, bromine, potash, copper, uranium
Less environmental impact than other methods
Less surface area is disturbed
Acids, heavy metals, uranium can accidentally leak

34. A mining method: undersea mining
We extract minerals (e.g., magnesium) from seawater
Minerals are dredged from the ocean floor
Sulfur, phosphate, calcium carbonate (for cement), silica (insulation and glass), copper, zinc, silver, gold
Manganese nodules = small, ball-shaped ores scattered across the ocean floor
Mining them is currently uneconomical
Hydrothermal vents may have gold, silver, zinc
Mining would destroy habitats and organisms and release toxic metals that could enter the food chain

35. Restoration of mined sites
Governments in developed countries require companies to reclaim (restore) surface-mined sites
Other nations (e.g., Congo) have no regulations at all
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 mandates restoration
Companies must post bonds to ensure restoration

36. 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
Remove heavy metals
pH is moderated

37. The General Mining Act of 1872
Encourages metal and mineral mining on federal land
Any citizen or company can stake a claim on any public land open to mining for $5 per acre
The public gets no payment for any minerals found
Once a person owns the land, that land can be developed for any reason, having nothing to do with mining
Supporters say it encourages a domestic industry that is risky and provides essential products
Critics say it gives land basically free to private interests
Efforts to amend the act have failed in Congress

38. Minerals are nonrenewable and scarce
We must recover and recycle our limited supplies
Once known reserves are mined, minerals will be gone
For example, indium, used in LCD screens, might only last 32 more years
Gallium (for solar power) and platinum (fuel cells) are also scarce
Reserve estimates are uncertain
New discoveries, technologies, consumption patterns, and recycling affect mineral supplies
As minerals become scarcer, demand and price rise

39. Years remaining for selected minerals
Scarcity increases prices
Industries will spend more to reach further deposits

40. Factors affecting how long deposits last
Discovery of new reserves increases known reserves
Minerals worth $900 billion were discovered in Afghanistan in 2010
New extraction technologies reach more minerals at less expense
Changing social and technological dynamics modify demand in unpredictable ways
Lithium batteries are replacing cadmium-nickel ones
Changing consumption patterns affect how fast we exploit reserves (e.g., a recession depresses demand)
Recycling extends the lifetimes of minerals

41. We can use minerals sustainably
Recycling addresses:
Finite supplies
Environmental damage
35% of metals were recycled in from U.S. municipal solid waste
7 million tons
Steel, iron, platinum, gold, nickel, germanium, tin, and chromium
Reduces greenhouse gases by 25 million metric tons

42. CONSERVING GEOLOGIC RESOURCES

43. Types of Geologic Resource Conservation
Recycling is common for aluminum, platinum, gold, silver, copper, lead
Steel and iron recycling is easily done at minimills (photo to left). Cars also contain platinum as a catalytic converter catalyst.
Substituting new materials (polymers, high-tech alloys, glass cables, etc.)

44. Recycling of Aluminum - A Big Success Story
Aluminum must be extracted from bauxite by electrolysis. This requires lots of energy!
Recycling waste aluminum consumes one- twentieth the energy of extraction from raw ore.
Nearly two-thirds of all aluminum beverage cans in US are recycled.
It makes environmental and economic sense to recycle aluminum. Everyone agrees!

45. We can recycle rare 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
1.2 billion cell phones sold each year contain 200 chemicals and precious metals
Phones can be refurbished and resold or dismantled and their parts reused or recycled
Only 10% of cell phones are recycled
Recycling reduces demand for virgin ores and reduces pressure on ecosystems

46. Conclusion
We depend on minerals and metals to make the products we use
Mineral resources are mined by various methods
Contributing to material wealth
But causing extensive environmental damage (habitat loss, acid drainage, etc.)
Restoration and regulations help minimize the environmental and social impacts of mining
Maximize recycling and sustainable use of minerals 46