EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The use of aluminium-based alloys has been steadily increasing in different product sectors such as transportation, construction, electronics, packaging, etc. Recycling of materials from end-of-life products is essential to close the material loop and reduce the environmental footprint in production. The increasing use of aluminimum in packaging applications results in many different aluminium-based products ending up in consumer mixed-waste bins. This waste is typically incinerated, generating an aluminium-containing bottom ash. The current work investigates the recyclability of the aluminium fraction in the bottom ash from waste incineration plants in the USA, UK and Denmark. Incinerated Al-samples from different size fractions (2-6mm, 6-12mm and 12-30mm) were characterized in terms of inherent oxide thickness, re-melting yield/coagulation and composition. The measured average oxide thickness on Al particles was 68 µm ±100, with the metal yield and coagulation efficiency measured to between 76-92% and 87-99% respectively. Larger particle size fractions resulted in a higher metal yield due to their higher mass to surface ratio. A simplified model correlating metal yield and particle size was proposed. The aluminium content of the melted material was determined to between 95.6 and 98.5% with main impurities being Fe, Si, Mn, Zn, Mg and Cu, corresponding to major aluminium alloying elements and waste charge components.