IBA: An Untapped EU Metals Source

Key Takeaways

• Bottom ash from incineration (MWIBA) is now a priority stream for copper/aluminium recovery under the EU Critical Raw Materials Act.
• The EU produces approximately 18.7m tonnes of MWIBA yearly, holding 2-5% recoverable metals, two-thirds aluminium.
• In 2021, only 223,200t aluminium and 39,210t copper were recovered from 9m tonnes of ash.
• Full processing could add 430,000t aluminium and 150,000t copper, though figures are uncertain.
• JRC proposes targets: 30% aluminium, 40% copper; no EU-wide target yet exists.

Bottom ash from waste incineration contains recoverable quantities of copper and aluminium that are currently only partly captured. This is according to a report by the European Commission’s Joint Research Centre (JRC) informing the EU’s Critical Raw Materials Act.

The report treats bottom ash from municipal solid waste incineration (MWIBA) together with bottom ash from commercial and industrial waste incineration. It considers these as one of the priority waste streams for the recovery of strategic and critical raw materials under Article 26 of the Act. As a result, it identifies copper and aluminium as the main recoverable materials. There are also smaller quantities of nickel, platinum group metals and magnesium.

How Much Ash, How Much Metal

According to a Bottom Ash Factsheet published by the Confederation of European Waste-to-Energy Plants (CEWEP), around 96 million tonnes of municipal, commercial and industrial waste were treated in European Waste-to-Energy plants in 2018. This produced approximately 19 million tonnes of bottom ash. The JRC report puts annual MWIBA generation at around 18.7 million tonnes. This contains an estimated 2 to 5 per cent by weight of recoverable non-ferrous metals, of which aluminium accounts for roughly two-thirds. Elsewhere in the report, the total strategic and critical raw material content of MWIBA is put at 7 to 10 per cent by weight.

Recovery of aluminium and copper from bottom ash is already carried out at scale in some Member States. This includes Belgium and the Netherlands. The JRC cites these as evidence that the necessary technology is available.

A Gap Between Current And Potential Recovery

For 2021, the JRC estimates that around 223,200 tonnes of aluminium and 39,210 tonnes of copper were recovered from 9 million tonnes of processed MWIBA across the EU27 plus four other countries. Had landfill and waste directive targets been met, a further 3.15 million tonnes of ash would have been generated that year. Furthermore, full processing of all ash, down to a 2 to 50 millimetre fraction, could theoretically have yielded an additional 430,000 tonnes of aluminium and 150,000 tonnes of copper from a total of 21.8 million tonnes of MWIBA in 2021. However, the JRC describes these figures as highly uncertain. They are based on optimistic assumptions.

Aluminium and copper together make up around 60 per cent of the strategic and critical raw material content currently recoverable from bottom ash. Magnesium, nickel and platinum group metals make up a further 16.6 per cent by weight. These are recovered to some extent as alloying elements or through secondary streams, such as platinum group metals from copper slimes. However, the JRC was unable to quantify these volumes precisely.

Proposed targets and legal gaps

The report proposes proportional national recovery targets based on the measured aluminium and copper content of each Member State’s mixed waste. These targets start at 30 per cent for aluminium and 40 per cent for copper. There is also scope to raise these over time to 50 per cent and 65 per cent respectively using current best available technology.

Bottom ash can be separated into steel, copper and aluminium scrap, alongside more than 80 per cent usable mineral aggregate. Further hydrometallurgical processing could increase metal recovery rates, the JRC notes. However, this would also generate a large volume of residual waste with no use beyond landfill.

On the legal side, the Industrial Emissions Directive (2010/75/EU) requires incineration plants to keep the total organic carbon content of slag and bottom ash below 3 per cent, or loss on ignition below 5 per cent of dry weight. No specific EU target exists for recovering metals or minerals from bottom ash itself. This is a gap the JRC highlights alongside limited and non-harmonised data on ash volumes and composition, and the low economic value of some recovered fractions.

Bottom ash from commercial and industrial waste incineration was added to the priority list on the basis of expert opinion and stakeholder input rather than dedicated data. The JRC notes this, as robust figures on its recovery potential remain largely unavailable.

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