ALUMINIUM RECOVERY FROM NON-SEPARATELY COLLECTED CANS
A number of aluminium cans end up in mixed residual waste, which is subsequently treated in waste-to-energy plants. The remaining aluminium is recovered from the incinerator bottom ash.
Until we can prevent recyclables from ending-up in waste-to-energy plants, we should consider the recovery of aluminium from incinerator bottom ash as a medium-term option. At the same time, it is important that the quantities of ingoing packaging waste and the outgoing recovered material going through incinerator bottom ash treatment are officially registered in all EU Member States. After the removal of the remaining contaminants (e.g. dust, minerals), it is permitted to include these quantities for achieving the real aluminium recycling rates in Europe, including for cans.
Nowadays, a wide range of bespoke advanced technologies offer new ways of extracting aluminium from incinerator bottom ash. Liquisort, a Dutch company, has developed a new sorting technology which uses special magnets in combination with magnetic fluids to separate aluminium from bottom ash. This technology, along with eddy currents, makes it relatively easy to separate aluminium from other metals. Since the separation technology uses a single material property, namely its density and does not depend on the size or shape of the particles, it is possible to achieve a clean separation, thereby producing pure aluminium that can be fully recycled. The technology, which allows for extracting metal particles of a much smaller size than previously possible, is constantly evolving and improving. It is now being rolled out to various countries across Europe, beyond the Netherlands. In Denmark, thanks to the sustainable and innovative technology for the optimal utilisation of metallic waste from incineration plants used by the recycling company Scanmetals A/S, significant progress has been made over the past two decades, in improving recovery rates for aluminium from incinerator bottom ash through two more efficient permanent installations. One is stationed in eastern Denmark, whilst the other one is in the west. Now, partly sorted bottom ash is transported to one of the two plants, where it is possible to carry out a more accurate separation of the non-ferrous metals, including aluminium, with state-of-the-art X-ray transmission. Following that successful development in Denmark, in 2017 Scanmetals A/S and Amalgamated Metal Corporation (AMC) started operating a recycling and recovery plant in Willenhall (UK) to recover aluminium and other non-ferrous metals from incinerator bottom ash.
Although aluminium recovered from bottom ash currently contributes to increased recycling rates for aluminium in some key countries around Europe, there are obviously a few downsides to this option. About 10-15% of the aluminium rigid fraction is lost, including beverage cans, through oxidation. This could easily be avoided if this fraction was sent directly to modern sorting plants. Leaving recyclables in the residual household waste fraction for incineration also goes against the recently adopted EU legislation, which calls on Member States to take measures to ensure that waste that has been separately collected for preparing for reuse and recycling is not incinerated in the future. In practice, the reason why aluminium is still recovered from bottom ash is because of the inefficient or non-existent kerbside and on-the-go separate waste collection systems for aluminium beverage packaging. This leads to aluminium cans ending up in mixed residual waste and treated in waste-to-energy plants. The key to minimise the recovery of aluminium from bottom ash and reach higher recycling rates for aluminium cans is to set-up efficient kerbside and on-the-go separate collection systems, either through advanced EPR or DRS or a combination of both, backed up by smart technologies for collection and digital sorting systems and recycling infrastructure.
Improve Sorting and Recycling – Key messages:
Sorting and Recycling companies are invited to:
Equip sorting centres with at least two eddy current separators and invest in advanced sorting technologies and facilities, e.g. smarter high-volume, high-speed eddy current separators, recycling infrastructure and suitable recycling techniques;
Set industry standards for sorting and recycling to meet when they sort and produce high-quality recyclable aluminium;
Support R&I for new sorting technologies and recycling techniques and infrastructure, e.g. European funding, whether grants or loans or a combination thereof, and investments in new sorting techniques for packaging, transformation of the less performing techniques as well as new recycling technologies.
National Authorities are invited to:
Address unregistered collection and sorting outside EPR systems;
Properly register the recovery of aluminium from incinerator bottom ash and phase out this waste treatment option, providing that no recyclables end up anymore in waste-to-energy plants.