Mining

I. Mineral Resources

A. A mineral resource is a concentration of naturally occurring material from the earth’s crust that can be extracted and processed into useful products and raw materials at an affordable cost.

B. We know how to find and extract over 100 minerals from the earth’s crust, including fossil fuels, metallic minerals (Al, Fe, Cu) and nonmetallic minerals (sand, gravel, limestone). All mineral resources are considered non-renewable resources.

I. Mineral Resources

C. An ore is rock that contains a large enough concentration of a particular mineral – often a metal – to make it profitable for mining and processing.

1.High-grade ore: Large amount of mineral2.Low-grade ore: Small amount of mineral

I. Mineral Resources

D. What do we use these metallic mineral resources for?

1.Aluminum – packaging, cans, motor vehicles, airplanes

2. Iron – critical component of steel, used for buildings and motor vehicles

3. Manganese, cobalt, molybdenum, and chromium are all widely used to strengthen alloys of steel

I. Mineral Resources

4. Copper – Used for electrical wiring and plumbing

5. Platinum – Used in electrical equipment and in catalytic converters in cars

6. Gold – Used in electrical equipment, coins, chemical reaction catalysts, and jewelry

I. Mineral Resources E. What are non-metallic minerals used for? The

most widely used non-metallic minerals are sand and gravel.

1.Sand – used to make glass, bricks, and concrete2.Gravel – roads and concrete3.Limestone – Used for road rock, concrete,

cement, and building materials4.Phosphate salts – In inorganic fertilizers and in

some detergents

II. Removing Mineral Deposits

A. After suitable mineral deposits are located, several different mining techniques are used to remove them, depending on their location and type.

B. Surface mining – Shallow depositsC. Subsurface mining – Deep deposits

II. Removing Mineral Deposits

D. Steps in surface mining:1.Anything growing on the land (forest, ect) is

first cleared away. Then, gigantic mechanical equipment strips away the overburden- the dirt and rock about the mineral deposit. The waste dirt and rock are called spoils. Sometimes minerals can be dredged from streams – the wastes are then called tailings.

II. Removing Mineral Deposits

2. Four types of mining processes can then be used, depending on the land topography –

a)Open pit mining- big pits are dug and ores are removed

World’s largest open pit mine – Kennecott Copper Mine (in Utah). Considered the world’s largest human excavation.

Has been open since 1906, 2.5 miles across, .75 miles deep.

On US. National Register of Historic Places

II. Removing Mineral Deposits

b) Strip mining – for mineral deposits close to the earth’s surface that lay in horizontal beds. Strips or trenches are dug, and as a trench is depleted and new trenches are dug, the overburden is placed in the trenches.

II. Removing Mineral Depositsc) Contour strip mining – Used mostly to mine

coal on hill-sides. A huge power shovel cuts terraces into the side of a hill. If the land is not restored afterward, a highly erodible bank of soil and rock called a highwall is left over.

II. Removing Mineral Deposits

d) Mountain-top removal – Used predominately in the Appalachian Mountain area of the US. Explosives and large power shovels remove the tops of mountains, exposing seams of coal, and overburden is dumped in valleys, which often completely changes or ruins streams, wetlands, and rivers.

Mountain-Top Mining Clip:Steven Colbert discusses with leading Mining Scientist, Dr.

Palmer 1/18/10• http://www.colbertnation.com/the-colbert-re

port-videos/261997/january-18-2010/coal-comfort---margaret-palmer

II. Removing Mineral Deposits

E. Subsurface mining – Used to remove coal and metal ores too deep in to be extracted by surface mining.

F. Miners dig a shaft, blast open subsurface tunnels to reach the deposit, and remove coal or ore and transport it to the surface.

III. Environmental Consequences of Mining

A. Scaring and disruption of the land surface is one major issue with mining. Spoil banks, empty pits, and tailing piles are all left behind from mines. Any regrowth of vegetation is slow because there is no topsoil.

III. Environmental Consequences of Mining

B. Mountain top mining in Appalachia has buried 1,200 miles of streams and rivers, and 470 of its largest mountains have disappeared, leaving behind barren land and huge pits.

III. Environmental Consequences of Mining

C. Since 1980, millions of miners have streamed into tropical forests and other tropical areas in search of gold. These small scale miners use destructive techniques such as digging large pits, dredging sediments from rivers, and hydraulic mining- a technique, outlawed in the U.S., that uses water cannons to wash entire hillsides into collection boxes for removal of gold.

III. Environmental Consequences of Mining

D. Surface mining in tropical areas destroys or degrades biodiversity when forests are cleared and mining wastes pollute near-by streams and rivers.

III. Environmental Consequences of Mining

E. Surface mining sites can be cleaned up and restored but it is costly. The U.S. department of the interior estimates that at least 500,000 surface mined sites exist in the U.S.

F. Subsurface mining disturbs much less land then surface mining, and produces less waste material. However, it leaves more ore in the ground and is much more dangerous for miners. Subsidence (sinking of the ground) is a problem with surface mining.

III. Environmental Consequences of Mining

G. Mining causes major pollution to water and air. For example, acid mine drainage occurs when rainwater seeping through a mine or mine waste pile carries sulfuric acid, produced when aerobic bacteria act on iron sulfide minerals in spoils, polluting streams and groundwater.

H. Additionally, chemicals such as sulfuric acid, mercury, and arsenic are used to extract minerals from ore, and huge amounts of water are used to flush these toxic chemicals through ore piles. This contaminated water gets into streams and groundwater.

I. For example, highly toxic cyanide salts are used to extract gold from ore.

J. According to the EPA, mining has polluted 40% of watersheds in the western U.S.