Mining requires finding and then removing the rock layers above the metal or mineral resource. Economics and the depth at which the layer is located decide which technique is used. Once mined, the ore, metal, or mineral is processed and purified. All stages create waste as the ore is separated, processed, and smelted.
If the target ore is close to the surface and present in large quantities, the easiest choice is to dig an open pit or surface mine and remove the ore directly. If the target ore is on the surface but present in small quantities, placer mining uses water or sieves to separate the small quantities out of the rest of the rock or soil. Surface mining leaves obvious scars on the landscape and displaces ecosystems directly. Placer mining can lead to erosion and water pollution issues due to the volumes of water it requires.
Test Your Vocabulary
Choose the correct term for each of the following definitions:
Term
Definition
Underground mining.
Washing sediments with water to free up heavier minerals, which sink and can be retrieved (i.e., panning for gold).
Exposing mineral deposits by removing overlaying soil and rock or obtaining them directly from above-ground deposits.
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Which of the following mining techniques is used for surface deposits that are heavier than water?
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2.
Which of the following mining techniques does NOT leave large surface scars?
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__________ is found when ore is close to the surface and in deep layers.
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Which of the following mining techniques is the LEAST common in the United States?
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5.
Where does mining use energy?
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6.
Which of the following steps of mining and refining rare earth metals does NOT produce hazardous waste?
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7.
What are the consequences of increased mechanization of mining?
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8.
How does smelting separate the metal from the surrounding ore?
