In theory, aluminium can be recycled an infinite number of times -without any loss of quality. Another argument in favor of effective recycling is that producing recycling aluminium only requires 5–10% of the energy needed to produce primary aluminium production. Recycling aluminium is therefore rewarding and necessary, not only for environmental reasons but also from an economic perspective.
It is difficult to imagine modern life without aluminium, a material that is durable, lightweight, stable and corrosion resistant. Its numerous positive characteristics make it ideally suited for transport, mechanical engineering, sports and packaging- related applications. It is lightweight, an excellent conductor of electricity and heat, and can be combined with almost all other elements to adjust its properties. Another feature of aluminium, and one that is becoming increasingly important, is its outstanding recyclability. Aluminium recycling is therefore not only necessary and expedient for environmental reasons, but also from an economic point of view.
AMAG is one of the largest aluminium recyclers from a single site in Europe. In fact, AMAG was melting down scrap even before the Ranshofen smelter was shut down in 1992. These decades of experience allowed the company to develop unrivaled expertise. While it initially focused predominantly on process scrap and material for simple cast alloys, AMAG now uses the entire range of aluminium scrap and makes a significant contribution to realizing the EU’s Circular Economy Action Plan, which aims to turn waste back into high-quality products.
AMAG currently recycles almost 320,000 tons of scrap per year in the manufacture of high-quality products. Many different types of scrap arrive at AMAG, from high-quality, pure, external process scrap with qualities close to virgin material, to highly oxidized and organically impure scrap that, although cheaper to procure, presents additional requirements for preparation, process management and production. This means that a beverage can tossed into household waste can ultimately be recycled by AMAG.
A number of measures are necessary to recycle aluminium in an environmentally friendly and economically efficient manner:
While AMAG uses significant volumes of scrap in many of its cast alloys, it is also understandable that scrap can only be used to a limited extent when producing certain wrought alloys with high purity requirements. Thorough sampling and proper separation are essential to make the best possible use of the input materials. AMAG therefore takes representative samples of each batch of delivered material and conducts a chemical analysis, including determining the metal yield and organic chemistry.
2 Thorough seperation
As noted previously, aluminium readily combines with other elements, so it is important to sort and separate materials as effectively as possible to extract maximum value. Although it is true that aluminium can be infinitely recycled, mixing different alloys (i.e. not sorting and separating
scrap properly) can lead to unwanted elements accumulating in the finished material -which, in the case of aluminium, is neither economically sensible nor easy to rectify on an industrial scale. The elements most commonly alloyed with aluminium include iron, copper and zinc. While they are desirable in certain alloys with precise compositions, these elements are almost always counter-productive when mixed together.
Automated separation of scrap into different materials is therefore becoming increasingly important. AMAG has been setting the industry standard for automated separation for many years: regular investments in state-of-the-art analysis and sorting methods have made it a global leader in this field.
3 Differentiated under cover storage of input materials
Only following this high-tech analysis is the scrap sorted and separated based on its morphology and then transported to the relevant storage areas. At the same time, alloys are also separated into various alloy classifications, which is essential for alloy-to-alloy recycling but does entail more work to store the materials in a dry place under cover.
4 Alloy-to-alloy recycling
This means producing an alloy from scrap of the same alloy. It is easier to do this with production scrap generated before the material is actually used for its intended purpose than with mixed scrap from collected waste materials, although both sources are equally important. Mixed scrap is rarely in purer forms (e.g. painted, dusty, combined with other materials as a composite with plastic or steel, etc.). For this reason, it is rarely technically possible at present to produce a high-quality alloy exclusively using mixed scrap from collected waste materials. One important aspect of alloy- to-alloy recycling is sophisticated metal analysis. As AMAG works with scrap from many different sources, it tests for 30 elements in different concentration ranges.
5 Maximizing output using batch calculation for each smelting furnace
The key to ensuring high added value from recycled scrap is a sophisticated batch calculation that relies on a database with details of the type and quantity of all stored scrap, as detailed in point 2.
6 Downstream processes
Heavily oxidized impure scrap (dross, dust, fraction from waste incineration plants, etc.) must be smelted down with salts in (tilting) rotary drum furnaces.
This article illustrates AMAG’s broad commitment to aluminium recycling, the expertise it has developed over decades and how it makes use of even challenging scrap materials. Newly developed products such as AMAG Titanal® Green 80 and recycled rims made from AlSi7.Rec demonstrate how AMAG is pushing the boundaries of technical possibilities. However, it is important to remember that most aluminium products manufactured to date have not yet completed their first life cycle. Use of the smelting process to produce primary aluminium is therefore absolutely necessary to meet the continuously rising demand. In light of this, we should avoid concentrating solely on the recycled content of aluminium and instead focus more on the material’s overall CO2 footprint.
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