Aluminium Filtration by Bonded Particle Filters

Abstract

Non-metallic inclusions such as oxides, borides and carbides in aluminium melts are a major cause of product failure during both processing and use. To remove these inclusions, molten aluminium is usually filtered through a mechanical filter such as deep bed-filter, ceramic foam filter or Bonded Particle Filter (BPF). In this study three BPF from Pyrotek have been tested at Hydro's reference centre in Sunndalsøra. The filters had different grit sizes; 6, 10, and 14 (equivalent to 30, 50, and 70 ppi). The filters were mounted in the patent pending Drain Free filter box developed by Hycast. LiMCA was used at the upstream side of the two coarsest filter (Grit 6 and 10) and both upstream and downstream for the finest filter (Grit 14). Three samples from each of the filters have been studied in a light microscope, and inclusions have been counted using image analysis. In addition, PoDFA samples from the test with the finest filter were also analysed and discussed.