Extracting rocks, ores and minerals Cambridge IGCSE Environmental Management revision
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In plain words
Almost everything you own that was not grown was dug up. Getting it out of the ground is expensive and messy, so a mining company asks two questions before it starts. How do we reach it? And is it worth it?
10 things to know
- An ore is a rock that contains minerals and metals.
- Surface extraction is used when the deposit is close to the surface. The soil and rock lying on top, called the overburden, are removed and the deposit is dug out. Opencast, open-pit and open-cut mining make a large pit, dug in steps. Strip mining removes the overburden in long strips, to reach a deposit that lies in a flat layer.
- Subsurface extraction is used when the deposit is deep. In deep mining, or shaft mining, a vertical shaft is sunk and tunnels are dug out sideways from it to follow the deposit.
- Subsurface mining disturbs less land at the surface. It costs more, and it is more dangerous for miners, because tunnels can collapse or flood and gases can build up.
- Biological extraction uses living things. In phytomining, plants are grown on soil that contains metal compounds. The plants take the metal up through their roots and store it. They are harvested and burned, and the metal is extracted from the ash.
- In bioleaching, bacteria break down a low-grade ore and produce a solution that contains the metal. The metal is then extracted from the solution.
- Biological methods use little energy and do little damage, and they work on ores too poor to mine in other ways. They are slow.
- Before deciding to mine, a company carries out exploration to find the deposit, and studies the geology, which decides the method. It considers accessibility and terrain, the quantity of the deposit and its quality, called the ore grade, and the climate.
- An environmental impact assessment predicts the damage a mine would do and how the damage could be reduced.
- The final decision depends on supply and demand, cost and profit. High demand raises the price, which can make a poor or remote deposit worth mining.
Worked example
A company finds copper ore 40 m below flat ground. The ore is spread over a wide area. Suggest a method of extraction and explain the choice.
- The deposit is close to the surface, so surface extraction such as open-pit mining is suitable.
- Removing 40 m of overburden is cheaper and safer than sinking shafts and digging tunnels.
- The ground is flat, so large machines can be used and a lot of ore can be removed quickly.
Tips and tricks
- Ore grade means how much metal the ore contains. A high-grade ore gives more metal from each tonne of rock, so there is less waste and more profit.
- In phytomining the plants collect the metal. In bioleaching bacteria do. Keep the two apart.
It lands in your notebook with its questions as flashcards.
Extracting rocks, ores and minerals: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
What is the overburden?
It has to be removed before surface mining can begin.
Which method is subsurface extraction?
A shaft goes down to a deep deposit and tunnels follow it.
Which living things are used in bioleaching?
Bacteria break down the ore and release the metal into a solution.
What does ore grade describe?
It is the quality of the deposit.
Why is surface extraction usually cheaper than subsurface extraction?
Digging a pit is simpler and safer than tunnelling.
The price of a metal rises sharply. What is the most likely effect on mining?Stretch
A higher price covers the higher cost of extracting from a low-grade ore.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 7 marks. Write your answers on paper, then check them.
Extracting rocks, ores and minerals
Cambridge IGCSE Environmental Management 0680 · 7 marks · papermunch.org
Name ______________________________ Date ______________
Define the term ore.[1]
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A rock that contains minerals and metals.
Describe how phytomining is used to extract a metal.[3]
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Plants are grown on soil containing metal compounds. The plants absorb the metal through their roots and store it. The plants are harvested and burned, and the metal is extracted from the ash.
State three factors that affect the decision to open a mine.[3]
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Any three: the geology; accessibility and terrain; the quantity and quality of the deposit (ore grade); the climate; the environmental impact assessment; supply and demand; cost and profit.
Answers: Extracting rocks, ores and minerals
- 1. A rock that contains minerals and metals.
- 2. Plants are grown on soil containing metal compounds. The plants absorb the metal through their roots and store it. The plants are harvested and burned, and the metal is extracted from the ash.
- 3. Any three: the geology; accessibility and terrain; the quantity and quality of the deposit (ore grade); the climate; the environmental impact assessment; supply and demand; cost and profit.