Metals, glass, building materials, clay ceramics and most plastics are made from limited natural resources. Some items made from these materials can be reused, and this saves the most energy and reduces the impact on the environment. For example, glass bottles only need to be washed and sterilised before they can be filled again. Other products cannot be reused in this way, but they can be recycled.
The advantages of recycling compared to producing materials and objects from natural resources include:
The table shows the percentage of energy saved by recycling compared to extraction from a metal ore.
|Metal||Energy saved (%)|
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:
The amount of sorting required depends on the purity of the mixture of metals/materials, and also on how pure you need the final recycled metal to be. For example, copper for electrical wiring requires a very high purity, so if wiring is made from recycled copper, the waste copper will need processing before being melted again into copper for wiring.
However, steel used in construction doesn't need such a high purity. This means that scrap iron can easily be added to the steel furnace when steel is being made. This reduces the cost of making steel from iron ore.
Describe a simple way to separate aluminium from iron.
A magnet or electromagnet will attract iron but not aluminium.