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Extraction of Metals
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- 1Metal OresA rock which contains enough metal for extraction to be worthwhile. Usually the ore is an oxide of that metal.
- 2Profitability of Metal Extraction (2)1. If the market price of metal drops, it may not be worth extracting. If it increases though, it may be worth extracting more.
2. As technology improves, more metal can be extracted from a single rock. So now extracting metal may become worth it when it wasn't in the past. - 3Metal Extraction Chemically (3)1. This can be by Reduction or Electrolysis.
2. Some ores are concentrated before extraction.
3. Electrolysis can be used to purify an extracted metal. - 4ReductionThis uses carbon. Carbon reacts with the metal oxide to create just the metal along with carbon dioxide. This is because the carbon reacts with the oxygen. This often takes place in a blast furnace.
- 5The Reactivity SeriesIf the metal is above carbon in the reactivity series (potassium, sodium, calcium, magnesium, aluminium) electrolysis (more expensive) must be used. However any metals below carbon in the reactivity series (zinc, iron, tin, copper) can be extracted using reduction with carbon.
- 6Copper is Purified by Electrolysis (3)1. It can be easily extracted by reduction in a furnace (smelting).
2. The copper produced is impure, which doesn't conduct electricity well, and copper is used for electrical wiring.
3. Electrolysis is used to purify it, despite being expensive, because it will become a good conductor. - 7Electrolysis (4)1. The breaking down of substance using electricity.
2. Electrolyte (a liquid) conducts electricity. It is often made from metal salt solutions.
3. Electrolyte has free ions to conduct electricity.
4. Electrons are taken away by the positive electrode and given away by the negative electrode. As ions gain or lose electrons they become atoms and molecules and are released. - 8Electrolysis to get Copper (3)1. Electrons are pulled off carbon atoms at the positive electrode, so Cu2+ ions enter the solution.
2. Cu2+ ions near the negative electrode gain electrons and turn into copper atoms.
3. The impurities drop at the positive as sludge, while pure copper atoms bond to the negative electrode. - 9Displacement Reactions (2)1. More reactive metals displace less reactive metals as it will bond more strongly to the non-metal metal in the compound.
2. Scrap iron displaces copper from copper sulfate because it is more reactive (and cheaper). This creates iron sulfate and copper. - 10BioleachingBacteria gains energy from the bond between copper and sulfur (copper sulfide). This process separates the copper from the ore.
- 11PhytominingThrough growing plants that contain copper, the copper builds up in the leaves. They can then be burnt in a furnace, and the remaining copper can be collected from the ash left in the furnace.
- 12Environmental Issues of Metal Extraction (4)1. Causes noise.
2. Eye sore for landscape.
3. Loss of habitats.
4. Abandoned deep mine shafts can be dangerous after the mine has been abandoned. - 13Importance of Recycling Metals1. It avoids burning fossil fuels to get energy for extracting metals.
2. Energy isn't cheap, so saves money.
3. Recycling conserves resources of metal in the earth.
4. Cuts the amount of rubbish sent to landfill sites (which pollute the surroundings)