Aluminium and Aluminium Cans

The 375ml aluminium can was introduced to the Australian consumer market in 1969 replacing the heavier steel can for single-serve beverage packs. Progressively the aluminium can has been further light weighted, shedding more than 30% of its weight since the 1970s. In 1997 over 200 billion aluminium cans were sold world-wide, and Australians consumed over 2.6 billion aluminium cans in 1997/98, of which 54% were soft drink cans and 46% were beer cans. All beer and soft drink cans filled and sold in Australia are made from 100% recyclable aluminium. It has become the world’s and Australia’s most recycled container, and make up only 0.2% by weight of the domestic waste stream.

The beverage industry is a major user of aluminium, which is the most common metallic element on earth, making up about 8% of the earth’s crust. It is a very convenient, safe and practical material to use for packaging liquids. It does not break, is lightweight, chills quickly, has longer shelf life for contents, is easy to open and compact, which makes it cheap to transport and handle. Its smooth bright surface is suitable for labeling and it works well for high speed filling. It is easily recyclable without loosing its properties. Aluminium beverage cans can be recycled over and over again as there are no technical and economic barriers, resulting in a well-established secondary scrap market for the metal in Australia. For over a decade Australia has recycled aluminium cans at a recycling rate of 60% or higher.

What can I do?

Preparing aluminium products for recycling

Aluminium products, especially drink cans are 100% recyclable. Before recycling the products they should be reasonably clean and uncontaminated.

• Rinse the aluminium can with water. To conserve water, use left over washing water for this purpose. Make sure that there are no foreign objects inside the can as these can interfere with the recycling process.

• Clean aluminium foil which is not contaminated with food can be rolled into a small ball, adding other pieces onto it in the same manner. Aluminium foil trays or dishes should also be rinsed or wiped clean, folded or rolled into a small ball if possible.

Which aluminium products can be recycled?

• Aluminium soft drink and beer cans.

• Clean foil products such as pie dishes, Easter egg wrappers and foil trays.

All About aluminium

How is aluminium made?

Aluminium comes from the raw material bauxite, which is a mixture of aluminium oxides, iron oxides and clay. In Australia bauxite is mined from open cut mines in Queensland and Western Australia, and is found in deposits varying up to 100ha in area and about 5 metres deep. The bauxite laterite or caprock as it is also known is then mined and crushed into smaller pieces, and transported to the refinery to be refined into alumina or aluminium hydroxide.

At the refinery, crushed bauxite is mixed with a hot solution of caustic soda in units called digesters. The alumina dissolves under heat and pressure. Un-dissolved sand and mud, along with other impurities are filtered out and the caustic soda solution is then cooled in precipitator tanks to crystallise the dissolved alumina. This is then filtered again, washed and heated in kilns at 1000°C (calcination) to produce pure alumina, which is a white sandy powder.

Alumina is then shipped or transported to smelters located at either Queensland, Victoria or Tasmania, for production into aluminium. At the smelters, alumina is dissolved in a bath of molten sodium aluminium fluoride at about 900°C in large electrolytic cells called ‘pots’. A powerful electric current (electrolysis) is then passed through the liquid and the alumina is split into its aluminium and oxygen components. Metallic aluminium deposits in a pool at the bottom of the ‘pots’ and drawn off regularly and cast into ingots of various shapes and sizes. Large ingots can weigh up to 11 tonnes.

Some ingots are sold and exported. The ingots are scalped, pre-heated and rolled in mills to form coils of flat sheets for use in the manufacture of aluminium beverage cans. During the manufacture of aluminium cans and can ends, a lot of scrap metal is left over. This clean metal is melted down again and recast back into ingots.

How is aluminium recycled?

The aluminium drink cans collected for recycling are first sorted and then baled into bricks. The bricks are transported to the processing plant at Kaal Australia, Yennora NSW, and fed into remelt furnaces. The collected aluminium beverage cans are melted at about 800°C and the molten aluminium casted into ingots and sent to rolling mills to be rolled into new can sheets.

What is the environmental impact of recycling aluminium?

Recycling aluminium cans saves energy. Recycling aluminium cans only requires 5% of the total energy to produce new cans from bauxite, which means that 20 recycled cans can be made using the same amount of energy to make one new can. In addition, for every tonne of aluminium recycled about 5 tonnes of bauxite is also conserved. There is also less environmental damage.

Aluminium is a valuable metal with a high scrap value, fetching over $1000 per tonne. Its recycling has generated many millions of dollars to individuals and community groups that collect and sell the cans to recycling depots. The refundable 5 cents deposit under the Container Deposit Legislation system in South Australia has encouraged the highest return rate of cans in Australia.

Many of the collection and recycling depots are operated by community groups like Apex, Lions and Scouts, or charitable organisations as fund-raising ventures, where the money earned is returned back into community services. Jobs are also created to sort the cans in the recycling centres, transport them for reprocessing and remelting them at smelters.

Recycling cans reduces the amount of litter (1.4% of total SA litter stream). There is also a substantial saving in waste management costs, Council clean-up cost at public places, labour and transportation costs. Moreover, less landfill space will be needed resulting in cost savings in landfill development, management and remediation. A million aluminium cans in their semi-crushed state take up about 500 cubic metres of space.

References

Planet Ark, 1998, http://www.planetark.org/

Planet Ark, undated, The Planet Ark Recycling Report, Sydney NSW.

Recycle 2000 Fact Sheets.

Recycling Advisory Committee, 1990, Recycling of aluminium, information sheet. KESAB Litter Index.