Electromagnetic priming of ceramic foam filters (CFF) for liquid aluminum filtration

Abstract

Commercial Ceramic Foam Filters (CFF) of 30, 50 and 80 Pores Per Inch (PPI) have been primed, using magnetic field strengths of 0.06–0.2T, for periods of 1–10 minutes. The influence of time and field strength on the gas removal from the CFF structure, and the resulting improvements in filter productivity, are discussed. The obtained results are related to Finite Element Modeling (FEM) of the metal flow fields induced by the electromagnetic Lorentz forces. Higher filtration rates were obtained for 50 PPI magnetically primed, than for 30 PPI gravity primed filters. This suggests that electromagnetic priming offers an opportunity to use 50 PPI filters, with a higher overall filtration efficiency than 30 PPI filters, in existing cast house applications where the low productivity/high priming head of these filters would otherwise rule them out. Estimated filtration efficiency of different filter types are presented as functions of velocity and thickness.