Performance of Regular and Modified Ceramic Foam Filters (CFFs) during Aluminium Melt Filtration in a Pilot-Scale Setup

Liquid metal filtration through a ceramic medium has proven to be an efficient way to secure the removal of inclusions and bifilms from molten aluminium. With an increasing focus on recycling of metal values throughout the metallurgical industry, improvements in filter performance and efficiency is currently sought-after but hard to achieve. In the present study, a series of pilot-scale filtration trials have been performed using 30 ppi Ceramic Foam Filters (CPUs) with different surface chemistry and roughness. The trials were carried out with a commercial 6xxx aluminium alloy both with and without additions of grain refiners (AlTi5B1). The filter performance was evaluated by using the change in metal level over the filter to indicate the pressure drop, as well as by analysing LiMCA results. Moreover, microstructural analysis by LOM and SEM/EDX were carried out on spent filters, and current filtration theory used to explain the observed results.