VIEW: Mining
Mining
Some minerals are very useful. An ore is a rock that contains minerals with useful elements. For example, aluminum in bauxite ore is extracted from the ground, refined and used in aluminum foil and other products. Although mining provides people with many needed resources, the environmental costs can be high. The cost of creating a product from a mineral depends on how abundant the mineral is and how much the extraction and refining processes cost. A mineral deposit will only be mined if it is profitable. A concentration of minerals is only called an ore deposit if it's profitable. Environmental damage from these processes is often not figured into a product's cost. Often, pollutants from the mined rock, such as heavy metals, enter the soil, sediment and waterways.
Surface mining allows the extraction of ores that are close to the Earth's surface. In this method, usually the entire surface area is cleared in order to access the valuable minerals; examples include strip mining, open pit mining, and placer mining. Placers are valuable minerals, such as gold, found in stream gravels. Underground mining is used to extract ores deeper within the Earth. Tunnels are blasted into the rock to access the valuable minerals. Underground mining is usually more expensive than surface mining.
The valuable minerals must be extracted out of the ore deposits. This can be done by leaching (chemicals such as cyanide or arsenic are used to separate the ore), flotation (a compound is added that attaches to the valuable mineral and floats) or smelting (roasting the rock in order to separate it into layers). All can lead to air, water and soil pollution issues.
U.S. law has changed in recent decades so that a mine region must be restored to its natural state, a process called reclamation. This is not true of older mines. Pits may be refilled or reshaped and vegetation planted. Pits may be allowed to fill with water and become lakes or may be turned into landfills. Underground mines may be sealed off or left open as homes for bats.
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