Production of calcined alumina with a crystallite size which can be regulated with a narrow dispersion

摘要

The invention concerns a process for the production of alumina for ceramics by calcining alumina trihydrate in the presence of a mineralizer such as a halogenated compound and/or a boron compound, the calcined alumina being constituted by friable agglomerates of elementary particles, or crystallites, of alpha alumina, the average size of which can be fixed as required, with a unimodal narrow distribution of crystallite sizes, characterized in that calcining of the alumina trihydrate is carried out in an industrial kiln in a renewed oxidising atmosphere at a temperature in the range 800 DEG C. to 1300 DEG C. for a period of 0.5 hour to 4 hours in the simultaneous presence of a halogenated compound acting as a mineralizer and a silica based alumina recrystallisation modifier which is uniformly and intimately distributed in the alumina trihydrate charge.