AlF3 reactive Al2O3 foam filter for the removal of dissolved impurities from molten aluminum: Preliminary results

Lucas Nana Wiredu Damoah, Lifeng Zhang

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Filters coated with AlF3 can be used to filter molten aluminum to simultaneously remove nonmetallic inclusions and dissolved alkali and alkaline earth metal impurities. Coating experiments were carried out in which anhydrous HF gas was generated from reactions involving NaF or CaF2 and concentrated H2SO4, and used in a reaction with Al2O3 ceramic foam filter to produce a layer of AlF 3 coating on the surface of the Al2O3 filter. Samples from these experiments were studied by X-ray diffraction, scanning electron microscopy and electron probe microanalysis. Preliminary results of the coating experiments showed that it is possible to coat Al2O 3 filters with AlF3 by this method. Increasing the pressure of HF gas increased the yield of AlF3 in the filter. Theoretical evaluation of the removal efficiency of dissolve impurity elements showed that dissolved calcium can be removed up to 99.8% within 30 s of contact time between the filter material and the molten aluminum.

Original languageEnglish
Pages (from-to)896-913
Number of pages18
JournalActa Materialia
Volume59
Issue number3
DOIs
Publication statusPublished - Feb 2011

Keywords

  • AlF reactive filter
  • Aluminum
  • Dissolved impurities
  • Filtration
  • Inclusions

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