Materials for use in atmospheres containing HF in a pyrohydrolysis plant for re‐processing spent pot lining from aluminium production

Abstract Information was needed on materials behaviour in HF‐containing atmospheres of a fluidized bed for reprocessing spent pot lining from aluminium production at temperatures of up to 1180°C. A literature search was performed but, since it was only a limited success, corrosion experiments were started at 1100°C in an environment relevant to the above‐mentioned conditions. 22 different materials were tested, including powder metallurgically produced alloys and ceramic materials. Most of the materials failed after the relatively short testing time of 68 h. It was mainly two materials which showed corrosion rates of a more or less acceptable order of magnitude. These were the nickel base alloy Haynes no. 242 and the ceramic material SSiC. Since the conditions of the experiments represent the most extreme case conceivable for the plant under consideration (event of malfunction), it is assumed that these materials are suitable for longer‐term operation under regular conditions.