Mining and Mineral Resources Environmental Science Class Notes 03/21/17

Mineral Consumption per Person (U.S.)

What Is a Mineral? A mineral is a: Can be made up of naturally occurring inorganic solid characteristic chemical composition orderly internal structure characteristic set of physical properties. Can be made up of Atoms of a single element Compounds (atoms of 2 or more elements chemically bonded

Ore Minerals Ore Mineral- has economic value Gangue Mineral- has no economic value Ore and Gangue minerals are extracted together. Ore is separated from gangue In order to be profitable, the price of the ore must be higher than the costs to extract and

Metallic Minerals Ore minerals are either metallic or nonmetallic. Metals have the following characteristics: can conduct electricity have shiny surfaces are opaque

Nonmetallic Minerals Nonmetals have the following characteristics: tend to be good insulators may have shiny or dull surfaces may allow light to pass through

Mineral Resources and Their Uses Uses for nonmetals: Building materials Gemstones Uses for metals: Metals are easy to mold Metals conduct electricity Two or more metals combine to form alloys

Mineral Exploration Geologists go out into the field and find deposits Deposit is sampled to find quality and size of deposit Cost analysis to determine if mining will be profitable

Subsurface mining soil and rocks are removed to reach underlying coal or minerals. 50 m or more beneath Earth’s surface. Room-and-pillar mining common method of subsurface mining. used to extract salt and coal. Pillars of ore are left to support the roof of the mine

Longwall Mining more efficient method of removing coal from a subsurface seam. A machine called a shearer moves back and forth along the face of a coal seam. As coal is sheared from the long wall, it falls onto a conveyor and is transported out of the mine.

Solution Mining Used for deposits of soluble mineral ores potash salt sulfur Ore is injected with hot water Compressed air is then pumped into the dissolved ore Air bubbles lift it to the surface.

Surface Mining Soil and rocks are removed to reach underlying coal or minerals. Used for deposits close to Earth’s surface Ores are mined downward, layer by layer. Explosive are used to break up the ore

Quarrying A type of open-pit surface mining Used to mine for near-surface minerals Building stone Crushed rock Sand Gravel Clay Gypsum Talc Produces aggregates

Solar Evaporation Produces 30% of the world’s salt Useful in places with high temps and low rainfall Salt water is pumped into a shallow pond Water evaporates off, leaving salt behind

The Environmental Impacts of Mining All mining poses a significant threat to the environment Mining companies now have to prevent or fix those problems Environmental Impacts: Air and Noise Pollution Water Contamination Displacement of Wildlife Erosion and Sedimentation Soil Degradation Subsidence Fires

Air and Noise Pollution Surface mines produce lots of noise from equipment and blasting Dust is generated in mining process Regulations prevent mines from releasing dust or noise into larger environment

Water Contamination Water that seeps through mine sites can pick up or dissolve toxic substances. These contaminants can wash into streams, where they can harm or kill aquatic life. Regulations require companies to dispose of toxic products away from water sources.

Displacement of Wildlife Creation of mine = destruction of habitat Dredging rivers destroys river bottom ecosystems Can be helped by planning to replant the habitat after mining is finished

Erosion and Sedimentation Excess rock from mines is sometimes dumped into large piles called dumps. Running water erodes unprotected dumps and transports sediments into nearby streams.

Soil Degradation Soil at a mine site is removed from the uppermost layer downward. Storing soil layers can mix them up Layers should be put back in the order they originally were to prevent degradation

Subsidence Sinking of regions of the ground with little or no horizontal movement. Occurs when pillars that have been left standing in mines collapse or the mine roof or floor fails. We don’t know where all old mines are- we might build on top of a precarious mine

Underground Mine Fires Underground coal seams can catch on fire Lightning Forest fires Human-created fires Very difficult to put out- can take decades Smoke and gases can be released to the surface

Mining Regulation and Reclamation Mines on land in the United States are regulated by federal and state laws. Mining companies must comply with: the Clean Water Act and the Safe Drinking Water Act. the Endangered Species Act

Reclamation the process of returning land to its original condition after mining is completed. The Surface Mining Control and Reclamation Act of 1977 created a program for the regulation of surface coal mining on public and private land. established a fund that is used to reclaim land and water resources

State Regulation of Mining Mining companies must obtain permits from state environmental agencies before mining a site. State agencies inspect mines for safety State agencies can impose fines or shut down mines