Making aluminium requires a lot of energy. In fact, the commercial development of the metal in the late 19th century was largely due to the development and availability of cheap and abundant hydro-electric power which is still the principal source of the industry’s energy. The energy used to produce aluminium is 'trapped' in the metal. Re-melting aluminium to return it to ‘new’ metal takes only 5% of the original energy required. So 95% of the original energy investment always remains ‘stored’ in the metal.
How Does Aluminium Foil Meet Today’s Environmental Considerations?
All minerals on this planet are finite and they must be conserved and used wisely. But without their exploitation our way of life is in question and in some cases it is very difficult to change the way we use resources. Burning fossil fuels for heating, for example, is likely to be with us until the end of this resource is in sight.
Compared with this example, aluminium is in a very fortunate position. One of the most abundant elements present in the earth's crust, third only to silicon and oxygen, this element is so plentiful that demand is never likely to exceed supply.
Used aluminium has always been an important source of 'new' metal. According to industry estimates, about two thirds of aluminium in use is eventually recycled because it is so much cheaper to re-melt it in its metallic form than it is to extract the metal from the original ore.
Life Cycle of Aluminium Products
Dependent upon the use to which it is put, the life cycle of an aluminium product varies greatly.
Used in packaging, aluminium in the form of a foil food container might have a product life cycle measured in just a few weeks. At the other extreme, as a cladding material for buildings its life cycle may be measured in spans of anything up to a century.
So aluminium has a positive profile in terms of its plentiful availability, durability and its propensity to be reused at very low energy cost.
The positive contribution that aluminium foil can make to conserving other resources
Environmental Impact of Aluminium Packaging
With so much attention on the environmental demands of packaging materials, it is easy to lose sight of the environmental benefits these materials can bring. Take the case of sterilised food preserved without refrigeration for long periods thanks to the high barrier properties of an aluminium foil container or foil laminate pouch. Such a pack enables the transportation and storage of valuable food resources in a minimum of space and with a minimum of additional weight due to packing. Also, thanks to the metal's very good thermal conductivity, the energy used to heat the food contained in the pack is minimised - a further saving.
Another example: Food can be processed in a foil container, shaped by it, carried in it, delivered, displayed, carried home, baked or re-heated in it - all without any need for the contents to be removed from the one container. The resulting savings of energy and materials are considerable.
Where economies facilitated by a packaging material such as aluminium are obvious, it makes sense to use such a material, particularly when the potential for recovery and recycling is so strong.
That aluminium can be economically recycled, and has been since it became commercially available more than a century ago, is a well established fact. As a used material it retains a positive monetary value, unlike many other packaging materials which can cost money for disposal. The metal remains substantially intact in terms of volume and, for one twentieth of its original extraction cost, can be re-melted to become new metal ready for its next task. Several successful national schemes for the collection and recovery of used beverage cans (for the production of more beverage cans) represent clear evidence that aluminium packaging materials can be recycled with outstanding success.
Modern molten metal filtration techniques keep quality high, and the aluminium companies greatly value this rich source of secondary metal which is available at such a comparatively low energy cost.
What About Foil?
Although aluminium foil represents a tiny proportion of the total household waste stream (less than 0.5%), the aluminium industry is keen to have this valuable raw material returned.
Clean foil, such as ready-meal containers and catering trays, pie cases, kitchen foil, dairy product lidding and non-laminated chocolate wrapping, can be easily recycled in the secondary industry through a simple re-melt process. State-of-the-art reverbatory furnaces, with full environmental protection, keep melt losses to a minimum and deliver the 95% energy saving common to aluminium recycling. Aluminium has secure and growing end-markets, with much recycled metal being used for cast components, such as vehicle parts. The light-weighting of vehicles through increased use of aluminium means even more energy savings.
Recycling is not new to foil. For over forty years, and thanks to its metal value, used foil from packaging has been widely collected to raise money for charity. With the growing awareness of the importance of environmental matters in recent years. European Directives, recycling levies and land-fill taxes have now taken over where charity was once the main driving force. All packaging materials are now subject to strict recycling and recovery controls in Europe.
Heavy Investment by the Aluminium Foil Industry
Without the background of environmental legislation, the aluminium industry is well motivated to recover all the used metal it can, from whatever use. It wants to have its metal back at a lower energy cost than virgin metal.
This is why there has been considerable investment over several years into finding better ways to recycle the metal. For example, one major group of companies who supply the thin foil used for the laminates for drinks cartons carried out a feasibility study which demonstrated that it is possible to separate the metal from the plastics and board materials, and to return the used aluminium to make more foil.
Now the same group has set up a joint venture to establish a dedicated plant to recover the metal from drinks cartons and to recover the energy from the other materials - mainly paper and board.
Eddy Current Technology
Separating the valuable aluminium components from a mixed waste stream has been an important area of technical advance in recent years. The technique which exploits the phenomenon of ‘eddy currents’ set up by rapidly alternating magnetic fields and which has the effect of separating metal-bearing items from a mixture of materials, is widely used in the management of household and industrial waste.
The aluminium industry has been active in bringing attention to the technique and has, in some instances, helped to sponsor trial installations designed to demonstrate its benefits.
Recycling Foil From Laminates
Laminated packs containing aluminium foil are environmentally highly efficient, because of their low demand on material resources compared to other packages offering similar product protection. Low pack weight means low use of energy during distribution.
Until recently, it was considered that the metal used in foil laminates could not be economically recycled. However, on the positive side, the energy locked into the metal can be recovered in energy-from-waste plants.
Thanks to considerable research by the aluminium industry, ways have been found to separate the materials, and to recover the metal. Alternative uses of the separated residues are another valuable field of study with, in one example, the shredded aluminium foil becoming a raw material in the production of cement products.
In countries where the recovery of energy from the incineration of waste is the accepted practice, aluminium foil becomes a useful source of heat energy. Under the furnace conditions of an incineration plant, foil releases its latent energy by combining with oxygen to release heat. Although aluminium foil is a tiny proportion of the total waste stream, it is nonetheless a positive fuel substitute, helping to reduce the amount of fossil fuel needed to sustain the incineration process.
During oxidation, aluminium gives off no polluting or ‘green house’ gas and the resulting residue represents the return of the metal to aluminium oxide, an inert compound similar to that from which the metal was originally extracted. In less pure forms, aluminium oxide occurs in most soils, and disposal of this residue is therefore totally safe.
Throughout the world, efforts are being made to minimise landfill waste disposal. Even if aluminium foil must be included in waste destined for landfill, it has the virtue of non-toxicity. Aluminium adds no poisonous compounds to the soil or ground water. Left to the effects of natural ‘decomposition’, the metal will very gradually oxidise over a period of many years returning to aluminium oxide without the emission of gas or pollutants. The rate at which this happens will, of course, depend on whether and how the metal is coated or laminated.
By reducing the metal’s contact with oxidising agents, some coatings will preserve the metal for periods of many years. Eventually, however, it inevitably ‘returns to nature’.
In parallel with recycling and recovery, source reduction is an important method of minimising the effect of packaging materials on our environment. For many years, the use of less and less metal to do a given job without loss of performance has been a challenge welcomed by the foil industry.
Considerable achievements have been made with savings in some instances of around 30% compared with 20 years ago.
This has been facilitated through improvements in casting and rolling techniques, more sophisticated measuring controls and equipment, and the development and use of alloys designed for specific applications - so called ‘tailored alloys’.
Aluminium foil, used in packaging, is itself an enabling factor in the minimisation of materials. A laminate incorporating a foil layer needs much less paper or plastic to perform a given barrier task than a laminate without foil. Foil containers enable serious collateral processing savings to be made thanks to its ability to act as a receptacle throughout the whole of the food preparation and distribution.
EAFA also encourages the industry's customers to take source reduction seriously, and through its own publicity and the European Aluminium Foil Packaging Awards seeks to promote this aspect in the application of its members' products.
The Drive Continues
The reduction in the use of all materials including coatings, supporting laminates, the recovery of such things as solvents, the installation of more fuel-efficient annealing furnaces etc. will continue to be high priorities of the industry. In such cases, optimising resources equates to the maximising of economic success - a powerful motivator which is quite apart from the increasing number of regulatory environmental measures which face all industries.