4. How are ores deep beneath Earth's surface removed?
Ores that are deep beneath the Earth's surface are typically extracted through underground mining methods. This involves the creation of tunnels or shafts to access the ore deposits. The most common methods include:
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Shaft Mining: Involves vertical shafts being dug down to the ore deposit. Workers and materials are transported down through these shafts.
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Room and Pillar Mining: This method creates large rooms where miners extract ore while leaving pillars of material to support the ceiling.
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Cut and Fill Mining: Involves mining an ore body in horizontal slices, filling the mined-out sections with waste material or backfill to support the remaining structure.
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Block Caving: A method where the ore body is undermined, causing it to collapse under its own weight, allowing for easier extraction.
These methods require careful planning and engineering to ensure safety and minimize environmental impact.
5. How are ores near Earth's surface removed?
Ores close to the Earth's surface are generally extracted through surface mining methods. Common techniques include:
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Open-Pit Mining: This method involves removing large, spoon-shaped sections of earth to access the ore. It is used when ore is found in horizontal beds relatively close to the surface.
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Strip Mining: Used for deposits that are located in horizontal beds, strip mining involves stripping away the surface layers to reveal and extract the ore beneath. It's commonly used for coal, but can also apply to minerals like copper and iron.
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Mountaintop Removal: A form of surface mining typically used for coal, where the tops of mountains are removed to access the coal seams beneath.
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Quarrying: Involves extracting stone, gravel, or minerals from the ground at or near the surface.
6. What two problems can result from removing waste material from ores?
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Environmental Degradation: The extraction and processing of ores often result in the removal of large amounts of waste material, which can lead to habitat destruction, soil erosion, and disruption of local ecosystems. Additionally, tailings (waste left over after extracting valuable minerals) can generate water pollution if not managed properly.
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Toxicity and Pollution: Waste materials can contain heavy metals and other harmful substances that can contaminate soil and water sources. If these toxic substances leach into the environment, they can pose risks to human health and wildlife, leading to long-term ecological damage and potential health crises in nearby communities.