Recycling materials
Waste materials such as A large molecule formed from many identical smaller molecules known as monomers. and Shiny element that is a good conductor of electricity and heat, and which forms basic oxides. are often disposed of in Places where refuse is buried underground.. Waste polymers may be Burned, particularly at a high heat.. However, these disposal methods waste valuable Anything that is useful to people. , including these Basic material that goods are made from such as crops, metals, wood and animal products such as wool and leather.:
- Mixture of hydrocarbons, mainly alkanes, formed over millions of years from the remains of ancient dead marine organisms. for making most polymers
- metal A rock containing enough quantities of a mineral for extraction to be possible. for making most metals
These are A resource that is no longer being made or which is made extremely slowly, such as crude oil and metal ores. - they form extremely slowly or are no longer being made. Reusing materials or reprocessing waste materials to produce new materials. reduces the problems of disposal, and also conserves raw materials.
Recycling polymers and metals
Recycling involves collecting used items and producing new materials from them. The first steps usually needed are:
- collecting used items
- transporting the used items to a recycling centre
- breaking up the items and sorting the different materials
Polymers
Recycling polymers also involves:
- sorting the different polymers from one another
- melting the waste polymer
- forming the polymer into a new A finished piece of work that is ready for a customer, audience or user.
Metals
Recycling metals also involves:
- sorting the different metals from one another
- melting the metal and removing impurities from the A term used to describe a liquid substance (eg rock, glass or metal) formed by heating a solid. metal
- solidifying the metal in A block of solid metal, usually rectangular in shape.
The ingots can then be used to manufacture new metal items.
Question
Describe a simple way to separate aluminium from iron.
A magnet or A magnet made by wrapping a coil of wire around an iron bar and passing an electric current through the coil. will attract iron but not aluminium.
Advantages of recycling
The advantages of recycling include:
- fewer oil wells, An area of land that is used to remove rocks for use in industries. or mines are needed
- less noise, dust and heavy traffic are produced
- smaller areas of natural A place where plants, animals and microorganisms live. are damaged
In addition, less The capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow. is usually needed to produce a material by recycling than is needed to produce it from its raw materials.
Question
This table shows the percentage of energy saved by recycling two metals compared to The process of obtaining a metal from a mineral, usually by reduction or electrolysis. from their ores:
| Metal | Energy saved (%) |
| Iron | 70 |
| Aluminium | 92 |
| Metal | Iron |
|---|---|
| Energy saved (%) | 70 |
| Metal | Aluminium |
|---|---|
| Energy saved (%) | 92 |
Suggest an explanation for the difference.
Aluminium is extracted from its ore using The decomposition (breakdown) of a compound using an electric current. 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
Disadvantages of recycling arise from the recycling process itself:
- the collection and transport of used items needs organisation, workers, vehicles and fuel
- it can be difficult to sort different materials from one another
- the sorted materials may need to be transported to where they can be processed