Recycling: Challenges for aluminium as an industrial material
Aluminium recycling is gaining in importance worldwide, not just as a source of raw materials but also as a contribution to resource efficiency. This is especially true against the backdrop of the increasing depletion of primary aluminium capacities in areas such as the EU. At the same time, the recycling of materials serves as one the most important factors to demonstrate the sustainability of aluminium as an industrial material.
Its significance is increasing in a time of shrinking raw material reserves and scarce, and above all expensive, energy. Recycled aluminium is produced in the form of cast and wrought alloys. There are no qualitative differences between alloys made from the primary metal and those made from recycled aluminium.
Collection, processing and transformation
Aluminium recycling to turn scrap into a reusable alloy consists of the three segments collection, processing and transformation. Numerous companies are active in each segment. Their highly developed technologies make it possible to process even contaminated scrap in an eco-friendly way, which greatly reduces metal loss. At the individual steps along the value chain, each company handles functions that prepare the scrap and other aluminium-containing materials to be used in melting furnaces. Not only old scrap (post-consumer scrap) will pass through these steps, but also production and processing scrap (new scrap) and waste materials generated during production and processing, such as aluminium dross and aluminium salt cake.
Important source of raw materials
Scrap supply is the bottleneck for the aluminium material cycle, since aluminium is used mostly in products with long service lives, e.g. in construction applications like windows or in cars. Windows, e.g., can have a service life of well over 50 years. That makes it necessary to wait a long time before the scrap can be recycled. Not least for this reason, about 75 per cent of all aluminium ever produced is still in use, meaning it’s not yet available for recycling.
Long before the need for sustainable development became a widely discussed topic, the global aluminium industry had already been running its material through a largely closed-loop cycle of metal production, processing, use and recovery. Product-related material cycles from production to processing and use to recovery of the metal are already largely closed today – depending on the application market. This has always been true for long-lived applications in cars and buildings – with recycling rates of about 95 per cent – and now for relatively short-lived product applications in packaging. Recycling rates of more than 80 per cent have been reached in this segment in Germany, and recycling rates continue to rise in the EU area, as well.
The aluminium industry is by no means resting on its laurels; instead, it continues to work on filling existing gaps in the circular economy. In order to recycle the raw material even more intensively in Germany, German aluminium companies are investing in the expansion of their recycling capacities, drawing on ultra-modern plant engineering technology.
Post-consumer scrap covers 20 per cent of aluminium demand
According to estimates by the International Aluminium Institute, about 17 million tonnes of post-consumer scrap accumulated worldwide in 2016. This volume will increase to about 21 million tonnes in 2020, representing a share of more than one third of today’s global production of primary aluminium. Today, about 20 per cent of aluminium demand is covered by old scrap – i.e. metal from products that have served their purpose. Another source of raw materials besides old scrap is new scrap. New scrap refers to, for example, waste generated in the production of semi-finished goods, sprues from casting foundries, or shavings from the mechanical processing of semi-finished goods and other products. Initially, increasing aluminium demand leads to higher demand for semi-finished goods, which results in a higher volume of scrap – unless process optimisation steps can be implemented to reduce the amount of accrued scrap. This is done to the extent possible, in part because it’s economically beneficial to companies: more scrap means less product and thus less efficient production.
Aluminium scrap is among the most economically valuable secondary raw materials. Recovering and recycling it conserves resources and makes an important contribution to limiting the rise of greenhouse gases. For that reason alone, using existing scrap is in the aluminium industry’s very own interest. The goal therefore must be to keep end-of-life aluminium products – whether they’re from construction, transport or packaging – in the reusable material cycle by leveraging appropriate collection systems, including end-of-life vehicle recycling, proper upgrading and dismantling, and deposit systems and/or recycling bins.
Thanks in particular to the lightweight construction megatrend, more and more aluminium is demanded and processed into a wide range of products. Once these are used up, they must be kept in the economic cycle as a valuable resource. The pool of aluminium scrap will grow exponentially, toughening the requirements for processing and sorting, on the one hand, and the metal trade as the link between the collection and melting down of old scrap, in particular, on the other.