Aluminium is the most abundant metal in the earth’s crust. Approximately 75% of aluminium ever produced is still in use today as it can be recycled endlessly without compromising any of its unique properties or quality.
Aluminium’s lifecycle provides significant benefits through recycling, saving 95% of the energy it would take to make new aluminium metal.
Recycling aluminium has five steps:
- collecting scrap;
- sorting scrap;
- remelting; and
There are two categories of aluminium scrap:
New Scrap – is surplus material that arises during the manufacture and fabrication of aluminium products, up to the point where they are sold to the final consumer. For example, off cuts of aluminium sheet or extrusions are considered new scrap. Sometimes, this new scrap can be safely recycled by aluminium smelters as its composition is known.
Old Scrap – is material that has been used by the consumer and subsequently discarded. For example, used beverage cans, window frames, electrical cabling and car cylinder heads are all considered old scrap. Aluminium smelters are unable to safely accept this old scrap as its composition is usually unknown and it can be contaminated.
Scrap aluminium is also collected from the community – from households, scrap merchants, local and regional authorities, etc.
The scrap is then sorted – grouping all coated (painted or lacquered) aluminium together, and grouping all uncoated aluminium together.
Paper, plastic and other non-aluminium recycling needs to be removed.
The sorted aluminium is then crushed into bales – by compacting the aluminium scrap, it reduces freight, storage and handling costs.
Uncoated scrap is loaded directly into a large furnace called a remelter, where it is heated at high temperatures and turned into molten form.
If the scrap aluminium is coated, it is processed through a gas fired rotary furnace to remove any coating and then transferred to the remelter.
The molten aluminium is cast at a temperature of just over 700°C to form ingots.