The next steps will depend on the material being recycled. For a metal, the following steps would be carried out:
The ingots can then be used to manufacture new metal items.
Glass is recycled by melting the objects being recycled. The molten glass can then be used to make new bottles or other objects.
Paper is recycled in a different way, as it cannot be melted. Instead, it is broken into smaller pieces, with water. The slurry of water and paper can now be reformed to make new sheets of paper.
The advantages of recycling compared to producing metals from metal ore include:
In addition, less energy is usually needed to produce a metal by recycling than is needed to produce it from an ore.
For glass and paper, the amount of energy needed to recycle the materials is less than the energy that would be needed to make them from their raw materials. For glass and paper, the energy saving is smaller than for metals. This is because metal extractions need a lot of energy through electrolysis or carbon reduction.
The table shows the percentage of energy saved by recycling compared to extraction from a metal ore.
Suggest an explanation for the difference.
Aluminium is extracted from its ore using electrolysis but iron is extracted by heating with carbon. Electrolysis uses more energy, so more energy is used to extract aluminium in the first place. Aluminium has a lower melting point than iron, so less energy is needed to melt it during recycling.
Disadvantages of recycling arise from the recycling process itself:
Other disadvantages relate to the materials themselves:
Describe a simple way to separate aluminium from iron.
A magnet or electromagnet will attract iron but not aluminium.