PROCESS FOR PREPARING ALPHA-ALUMINIUM OXIDE

摘要

Process for preparing aluminium oxide which has a proportion of alpha-aluminium oxide of at least 98% by weight and is largely present in the form of isolated particles having an average diameter of from 1 to 50 pm, in which granules which - comprise essentially aggregated primary particles of one or more transition aluminium oxides, in each case having an average primary particle diameter of from 5 to 50 nm, - have an average diameter of from 500 to 5000 pm and - have a tamped density of at least 250 g/l, are treated at from 800°C to 1200°C in an atmosphere containing at least 70% by volume of hydrogen chloride gas or at least 70% by volume of chlorine gas for a period of from 0.5 to 5 hours.