Abstract
This study investigates vacuum refining as a sustainable upcycling route for removing zinc (Zn) and other volatile impurities from recycled aluminium, addressing a key challenge associated with increasing recycled content in transport-sector aluminium scrap. Experimental results from laboratory- and kilogram-scale trials demonstrated that Zn can be almost completely removed from molten aluminium, with removal rates strongly enhanced by reduced pressure and elevated temperature. The process also produces Zn-rich condensates containing up to 98% Zn, creating opportunities for zinc recovery and reuse. Thermodynamic and kinetic analyses confirmed that Zn separation from aluminium is highly favorable, while pilot-scale evaluations highlighted the potential for industrial application. Despite remaining challenges related to scale-up, residence time, condensate handling, and process integration, vacuum refining shows strong promise for producing high-quality recycled aluminium alloys, improving resource efficiency, and supporting circular economy goals.