| abstract |
The present invention relates to a process for the production of α-alumina, wherein the transition alumina and / or the alumina feedstock which can be converted by heating to a transition alumina is calcined in an atmosphere containing at least 1% by volume of hydrogen chloride or at least 1% by volume. volumetric chlorine together with at least 0.1 vol% water vapor at 600 deg. C or higher, preferably 600 to 1400, especially 800 to 1200 deg. C. For example, aluminum hydroxide, alum or aluminum sulphate can be used as the aluminum oxide convertible raw material. The particles obtained are monocrystalline, have an octahedral or higher polyhedral shape, high purity alumina, are fine and homogeneous, have a narrow size distribution, do not agglomerate and can be obtained from raw materials of various kinds, purity, shape, size and composition.nŕ |