Chapter 27
Minerals and the Environment
Mining
• Removal of minerals & fossil fuels from the Earth’s crust.
Mining methods depend on:
• Depth of resources• Amount of stability of material that must be
removed (overburden) to reach the mineral• Topography• Safety• economics
Surface (strip) mining
• Removes deposits that lie in horizontal bed’s close the earth’s surface– Land is clear-cut– Overburden removed– Deposit is removed– Overburden replaced
• Long term environmental damage
Mountaintop Removal• Type of surface mining – Coal• Coal seams are exposed by removing the
tops of mtns., using explosives and/or heavy equipment
• Overburden dumped into adjacent valleys• Coal removed• Fed. Law requires reclamation
– Topography is never really restored
Open Pit Mining
• Huge hole dug using explosives & heavy equipment
• Deposit is removed• Pit is often filled with water that becomes
acidic or polluted with heavy metals from mine waste
Open Pit – Uranium Mining
Subsurface Mining
• Deep vertical mine shafts with horizontal tunnels branching off
• Used when deposits are too far underground to be reached by surface mining
• Less habitat destroyed• Much more dangerous
– Cave-in, collapse, explosions, poisonous gases– flooding
Drilling
• To remove liquids and gases• Deep shafts drilled into the earth to reach
geologic formations• Pressure usually forces the liq. Or gas to
surface– If no pressure, water or steam is injected
Environmental problems with drilling
• Platforms destroy habitat at surface• Liquids are susceptible to leaks & spills• Pipelines that carry liquids or gas result in
habitat loss
US Mining Laws
• The General Mining Law of 1872– Encourages the exploration & mining of
mineral resources– Allows corporations to acquire large tracts of
public land below market value– Corporations can remove valuable mineral
without paying adequate royalties or sufficient cleanup
The Surface Mining Control & Reclamation Act of 1977
• Mined land must be restored to pre-mined state– Disposal of waste– Re-contouring land to get back topography– Replant native vegetation
How Mineral Deposits Are Formed
• Ore Deposits – formed when metals are concentrated in anomalously high amounts by geological processes
• Mineral resources are usually extracted from ore deposits
Resources and Reserves
• Minerals are classified as:– 1. Mineral Resources
• Elements, chemical compounds, minerals or rocks that can be extracted to obtain a usable commodity
• The combination of reserve.– 1. Mineral Reserves
• The portion of the resource that is identified and from which usable materials can be legally and economically extracted at the time of evaluation
Availability of Mineral Resources
• When the availability of a mineral becomes limited, there are 4 possible solutions:1. Find more sources2. Recycle and reuse what has already been obtained3. Reduce consumption4. Find a substitute
Impacts of Mineral Development
• Environmental Impacts– Depends on many factors – mining procedures,
climate, rock type, etc.• Social Impacts
– Increased demand for housing and services in mining areas
Minimizing Environmental Impact of Mineral Development
• Environmental regulations at the federal, state and local levels
• On-site and off-site treatment of waste• Practicing the 3 R’s of waste management
Minerals and Sustainability
• R-to-C Ratio– A measure of the time available for finding the
solutions to depletion of nonrenewable resources
– R = known reserves– C = rate of consumption