Mining Practices and Impacts

Derrick Willard

Why do we mine things?

What is in the crust?

*Very little in a pure state-most metallic minerals existconcentrated in rocks called ores

Bauxite Ore(aluminum)

We also mine nonrenewable fossil fuels…

• Coal (focus of this presentation)• Oil• Natural Gas

Coal Types & Uses

Coal Found in 32 States

Valued for energy and steel production

Identifying Mineral Deposits (costs $$$$$ to find them…)

• Aerial photos• Radiation detectors• Magnetometer• Gravimeter• Deep well drilling• Seismic survey• Chemical analysis

Acquiring Land for Mining

• The General Mining Law of 1872 has served to reduce “start up” costs and maximize profits for “hardrock” mineral companies in the U.S.A on public lands– $2.50/acre fro an open-pit mine– $5/acre for a “vein”– No claim limit/claims don’t expire– No royalties have to be paid out

Q. Just how much land are we talking about?

A. About 270 million acres (or 1/4 of USA)

Mining Techniques

• Surface Mining– Extracts 90% of nonfuel mineral and rock– Extracts 70% of coal

• Subsurface Mining– Extracts coal and metal ores too deep to

reach by surface mining

Methods of Coal Mining

US Mining Trends

Pros and ConsSurface Subsurface

-disturbs large area

-produces large amounts of spoil-relatively safe-cheaper-more efficient

-disturbs much smaller surface area-spoil often left in mine-dangerous-expensive-less efficient

Surface Mining

• Strip out overburden (becomes spoils or tailings)

• Five land methods possible– Open-pit (quarry)– Area strip mining (flat terrain)– Contour strip mining (hilly terrain)– Mountaintop removal*– Placer mining (in riverbeds-usually gold or silver)

• Clean up (reclamation)

“Overburden” Removal

A Dragline Shovel

Mining Trucks

*To the left is a photograph of a Liebherr 360 ton (327 metric ton) haul truck. This unit is powered by a 2750 horse power engine and weighs 443,000 pounds (177 tons) empty...

Open Pit Copper Mine near Silver City, NM

Area Strip Mining

Area Strip Mine (Coal)

Contour (Bench) Strip Mining

Contour Mining in KY“Highwalls”

The “New” Technique

Mountaintop Removal Mining

Mountaintop Removal and Valley Fill (WV)

The top of a mountain has been pushed into a valley

Mountaintop Removal Coal Mine in Southern WV

Mountaintop(s) Removal near Kayford Mountain, WV

Mountaintop Removal-Up Close (spoil pile)

Subsurface Mining

• Deep vertical shafts used to reach coal and ores too deep for surface mines– Blasting– Drilling and excavating machinery

• Once underground…– Room-and-Pillar method (coal pillars)– Longwall method (metal supports)

Subsurface Mine Types

Longwall Mining

Longwall Mining Machine

Room and Pillar Mining

Room and Pillar Mining

Room and Pillar Mining Machine

Load Out

Regardless of how it is mined, coal is crushed into a standard size. Then the coal loaded onto trains for shipment across the U.S.A. to use for making steel and generating electricity.

Impacts of Mining Coal

• Scarring and disruption of area (ugly)• Erosion increases if reclamation not

done properly• Subsidence (sinkholes)• Toxins released (dust, gas,drainage)--

possible soil, air, water pollution• Acid mine drainage (esp. sulfur…)• Slurry (coal waste) pond overflow

Scarring in Tennessee

Subsidence over a Coal Shaft in Colorado

Coal Mine Subsidence in Colorado

Centralia, Pennsylvania (where a coal vein fire started in 1961)

Centralia, Pennsylvania (Helltown, USA)

Centralia, Pennsylvania (almost abandoned)

Centralia, Pennsylvania (Highway 61)

Acid Mine Drainage*results when the mineral pyrite (FeS2) is exposed to air and water, resulting in the formation of sulfuric acid and iron hydroxide

Slurry Pond Spill in KentuckyOctober 2000

Surface Mining Control & Reclamation Act of 1977

• Came about due to concerns about damage from strip mining

• Regulates active mines and drives reclamation

• Requires permits for mining• Allows for inspection and

punishment• Requires companies post a

bond before mining to ensure cleanup is done

• Prohibits strip mines in National Parks

Reclamation

Restoration of abandonedsurface coal mine in Pennsylvania-now wild game lands

Sources for You to Explore

• http://www.xydexx.com/modernruins/centralia_gallery.htm

• http://www.mountainjusticesummer.org/facts/steps.php

• http://www.mii.org/reclcoal.html• http://www.blm.gov/education/00_resources/a

rticles/mining/reclaimingminedlandprovidesforthefuture.html

• http://www.wma-minelife.com/coal/coalhome.html