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 (2-6 mm, 6-12 mm and 12-30 mm) 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 (SD=100), with the metal yield and coagulation efficiency measured to between 76 and 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.

The objective of this research is for Ti6Al4V alloy turnings, generated during the machining of implants, to produce powders for the fabrication of Ti base coating via the cold spray method. In order to decrease the cost of powder production and increase the recycling rate of the turnings, the hydrogenation-dehydrogenation (HDH) process has been utilised. The HDH process consists of the following sequence: surface conditioning of the turnings, hydrogenation, ball milling (for powder production), and dehydrogenation. Afterwards, the properties of the recycled powder were analysed via phase, chemical, and morphological examinations, and size and flowability measurements. Usability of the powder in additive manufacturing applications has been evaluated via examining the characteristics of the deposit produced from this powder by the cold spray method. In short, promising results were obtained regarding the potential of the recycled powders in additive manufacturing after making minor adjustments in the HDH process.

The quality requirements of aluminum products are steadily increasing, and the presence of non-metallic inclusions have a large impact on the quality of aluminum products. Sedimentation is a widely applied technique to remove inclusions and the settling characteristic of particles is one of the most important parameters determining the removal efficiency. The settling characteristics can be modeled analytically through different approaches. A comparison of settling according to the Stokes and Schiller and Naumann drag force formulations was investigated and showed that Stokes drag is relevant for inclusions in aluminum melts. The settling of particles is analytically and experimentally investigated in this study by using a shape factor “K” based on Stokes law and online particle tracking by LiMCA (Liquid Metal Cleanliness Analyzer), respectively. The effect of the shape factor on settling velocities was observed clearly and the measured data show considerably slower settling than traditional models, indicating the effect of melt flow due to thermal convection.

Al₄C₃ particles form during the primary production of aluminum via molten salt electrolysis due to the carbon solubility and direct contact between bath, metal, and carbon anodes. Additional Al₄C₃ may form during melt processing through direct contact between the melt and carbonaceous materials. As a result of their small size and similar density to aluminum, removal of aluminum carbide particles can be challenging. If not removed, carbides can produce inclusion defects or poor surface condition in aluminum products. The current work studies the removal and behavior of Al₄C₃ particles during flotation with different gas mixtures, as well as sedimentation. The interaction between carbide particles and Al₂O₃ films during the melt treatment processes was also studied and reported. Factsage thermochemical software was used to model the interactions at the interface of inclusions and bubbles covered by films. The highest degree of carbide removal was obtained after flotation with an H₂O-containing argon gas mixture, where the carbide concentration dropped below the measured solubility limit of carbon at the corresponding temperature. Strong interaction between Al₄C₃ particles and Al₂O₃ films was observed during sedimentation which worked as an efficient removal method for the particles. Oxidation of carbides and formation of oxycarbides were suggested as the mechanisms promoting the attachment of carbides on oxide films.