Aluminium has been recycled since the days it was first commercially produced and today recycled aluminium accounts for one-third of global aluminium consumption world-wide. Recycling is an essential part of the aluminium industry and makes sense economically, technically and ecologically. At the end of their useful life, all aluminium products retain some worth which guarantees that it is possible to create value by recycling them into new products. Efficiency of aluminium recycling thus translates into high recycling rates for the various applications.
New and Old Scrap
Aluminium destined for recycling can be described with two categories: new and old scrap.
New scrap is the surplus material that is discarded during the manufacturing and fabrication of aluminium alloys (e.g. the splinters of sheet edge trimmings).
Most new scrap reaching the secondary industry comes directly from the manufacturing industry. It is usually of known quality and composition and often uncoated. It can therefore be melted down with little preparation. 100 % of the arising fabrication scrap is remelted by the aluminium industry.
Old scrap is aluminium material that is recovered when an aluminium article has been produced, used and finally discarded at the end of its useful life. Such scrap could be e.g. used beverage cans, car cylinder heads, window frames from a demolished building or old electrical conductors.
Old scrap comes to the recyclers via a very efficient network of metal merchants who have the technology to recover aluminium from motor vehicles, household appliances, etc. This is often done using heavy equipment such as shredders, normally together with magnetic separators to remove iron, and sink-and-float installations to separate the aluminium from other materials.
Processing of Scrap
Both types of scrap are processed prior to melting to get rid off any contamination that may be present. They are centrifuged and dried to remove the oil and water that may be present and then magnetically separated from any present iron. Used beverage cans are processed to remove the interior lacquer coating and the outside product display printing inks.
The recycling of old scrap is normally carried out by secondary aluminium refiners, whereas new scrap is predominantly recycled through aluminium remelters.
Secondary aluminium refiners convert most of their materials into foundry ingot, generally based on the aluminium-silicon alloy system with additions of other metals such as copper and magnesium. These ingots, fabricated according to recognised national or international specifications, go into the manufacture of aluminium cast components. A significant share of the secondary aluminium refiners’ output is also delivered in a molten form by road tanker to large foundry users thus eliminating the need for further melting operations.
Alloy ‘hardeners’ are also produced. These ingots, with a high known percentage content of alloying metals, are used by other sectors of the aluminium industry such as primary smelter cast houses or remelt units located at semi-finished aluminium plants.
Ramifications of High Aluminium Recycling Rates
In Europe, aluminium enjoys high recycling rates, ranging from 41 % in beverage cans to 85 % in building and construction and 95 % in transportation. Since the material can be recycled indefinitely without loss of quality, and because of the high intrinsic value, there are strong natural incentives to recover and recycle aluminium products after use. Comprehensive systems for the recovery of used aluminium now exist in all major European countries.
The above figures represent a total annual production in Europe of 1.9 million tonnes of recycled aluminium. Thirty-two percent of European aluminium demand is satisfied by recycled material. A large majority of recycled aluminium is consumed by the transport sector. The other main markets are engineering, packaging and building.