Minerals and the Environment

2. Domestic and foreign companies take out $2-$3 billion/ year I. Mining Law of 1872 – encouraged mineral exploration and mining. 1. First declare your belief that mineral deposits are on the land. Then spend $500 in improvements, pay $100 per year and the land is yours 2. Domestic and foreign companies take out $2-$3 billion/ year 3. Allows corporations and individuals to claim ownership of U.S. public lands. 4. Leads to exploitation of land and mineral resources.   http://seattlepi.nwsource.com/specials/mining/26875_mine11.shtml 2

-- Senator Dale Bumpers (D- AR, retired) "This archaic, 132-year-old law permits mining companies to gouge billions of dollars worth of minerals from public lands, without paying one red cent to the real owners, the American people.  And, these same companies often leave the unsuspecting taxpayers with the bill for the billions of dollars required to clean up the environmental mess left behind." -- Senator Dale Bumpers (D- AR, retired) 3

Nature and Formation of Mineral Resources A. Ore – a concentration of naturally occurring material in or on the earth’s crust that can be extracted and processed at an affordable cost. Mineral and energy resources such as coal, oil, gold, and copper are nonrenewable resources. 4

Nature and Formation of Mineral Resources 1. Metallic Mineral Resources – iron, copper, aluminum 2. Nonmetallic Mineral Resources – salt, gypsum, clay, sand, phosphates, water and soil. 3. Energy resource: coal, oil, natural gas and uranium 5

Ore Formation 1. Magmatic Concentration – magma cools and crystallizes into various layers with denser Fe and Mg containing magma sinking while lighter Si containing magma forming upper layers 6

Ore Formation Hydrothermal Processes: most common way of mineral formation A. Gaps in sea floor are formed by movement of tectonic plates B. Water enters gaps and comes in contact with magma C. Superheated water dissolves minerals from rock or magma D. Metal bearing solutions cool to form hydrothermal ore deposits. E. Black Smokers – upwelling magma solidifies. Miniature volcanoes shoot hot, black, mineral rich water through vents of solidified magma on the seafloor. Support chemosynthetic organisms. 7

Ore Formation Manganese Nodules (pacific ocean)– ore nodules crystallized from hot solutions arising from volcanic activity. Contain manganese, iron copper and nickel. 8

Methods For Finding Mineral Deposits A. Photos and Satellite Images B. Airplanes fly with radiation equipment and magnetometers C. Gravimeter (measures local difference in gravitational forces) D. Drilling E. Electric Resistance (measure resistance of the Earth to the passage of an electric current) F. Seismic Surveys G. Chemical analysis of water and plants 9

Methods of Mining Surface mining open-pit mining dredging copper, iron, sand, gravel, limestone dredging buckets and draglines scrape underwater deposits In surface mining, mechanized equipment strips away the overburden of soil and rock and usually discards it as waste material called spoils.

Methods of Mining Surface mining open-pit mining dredging copper, iron, sand, gravel, limestone dredging buckets and draglines scrape underwater deposits In surface mining, mechanized equipment strips away the overburden of soil and rock and usually discards it as waste material called spoils.

https://www.youtube.com/watch?v=U0odIwjRpAk

Strip mining overburden (and all vegetation) is removed in strips resource is removed spoil is replaced in rows spoil is susceptible to erosion (sediment pollution) rainwater leaches chemicals into ground water (acid drainage) Area strip mining: used where the terrain is fairly flat Contour strip mining: used on hilly or mountainous terrain

Mine tailings Mine tailings often include sulfide compounds When these react with water, sulfuric acid and toxic minerals can be washed into local water Ore has two components Ore mineral containing the desired metal Gangue the waste material Removing the gangue from the ores produces piles of waste called tailings.

Subsurface mining coal mining disturbs less than 1/10 as much land produces less waste more dangerous to miners than surface mining

Heap-leach Extraction heap-leach extraction - separating gold from low grade ores - spraying rock with a cyanide solution which dissolves the gold - mining sites are often left with high toxin levels Cyanide, a highly toxic chemical, is used to separate 85% of the world’s gold from waste ore.

Placer Mining placer mining – mining streambed deposits for gold and other minerals Destroys riverbanks and vegetation along banks Increases sediment in rivers Uses heavy metals like Mercury that contaminate waters in the Amazon, gold miners are using mercury and have dumped 100 tons of mercury into the Amazon river

Minerals are extracted from ores by heating or chemical reactions Smelting - heating the ore - produces huge amount of air pollution (SOx) In the US, the mining industry produces more toxic emissions than any other industry After gangue has been removed, smelting is used to separate the metal from the other elements in the ore mineral. In the U.S., the mining industry produces more toxic emissions than any other industry.

Environmental Effects Steps Environmental Effects Disturbed land; mining accidents; health hazards; mine waste dumping; oil spills and blowouts; noise; ugliness; heat Mining exploration, extraction Processing Solid wastes; radioactive material; air, water, and soil pollution; noise; safety and health hazards; ugliness; heat transportation, purification, manufacturing Use Noise; ugliness thermal water pollution; pollution of air, water, and soil; solid and radioactive wastes; safety and health hazards; heat transportation or transmission to individual user, eventual use, and discarding Fig. 14.6, p. 326

Percolation to groundwater Leaching of toxic metals Subsurface Mine Opening Surface Mine Runoff of sediment Acid drainage from reaction of mineral or ore with water Spoil banks Percolation to groundwater Leaching of toxic metals and other compounds from mine spoil Leaching may carry acids into soil and ground water supplies Fig. 14.7, p. 326

Scattered in environment Smelting Separation of ore from gangue Melting metal Conversion to product Metal ore Recycling Surface mining Discarding of product Fig. 14.8, p. 327 Scattered in environment

A. Life Cycle of Metal Resources Mining Ore A. Ore has two components: gangue (waste) and desired metal B. Separation of ore and gangue which leaves tailings C. Smelting (air and water pollution and hazardous waste which contaminates the soil around the smelter for decades) D. Melting Metal E. Conversion to product F. Discarding of product 22

Recycle; increase reserves by improved mining Mine, use, throw away; no new discoveries; rising prices Recycle; increase reserves by improved mining technology, higher prices, and new discoveries B Production Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices, and new discoveries C Present Depletion time A Depletion time B Depletion time C Fig. 14.9, p. 329 Time