Spray-Dried Alumina Granules for Extrusion

Alumina granules were prepared by spray-drying technique with alumina-sol as the binder. The granule morphology is influenced by inlet temperature and the granule size. The decrease of inlet temperature and granule size benefits the granule morphology perfectible. Spray- dried granules were calcined at 800～1600°C, respectively. XRD and TG-DTA were carried out to analyze the phases of alumina-sol and granules. SEM was used to observe the granules calcined at different temperatures. The strength of granules was tested by the die pressing method. The results show that the alumina-sol not only acts as a common binder at room temperature but also improves the sintering behaviors of a-alumina, so as to make granules get good strength for extrusion as low as 1200～l300°C.