Kinetics of high-temperature thermal treatment of boehmite-based alumina in vacuum to produce pure alumina

The last stage of the hydrothermal oxidation of aluminum is based on high-temperature treatment of boehmite-based alumina in vacuum furnace to produce pure alumina. This process of alumina purification is studied experimentally with the use of a thin highly-porous layer of the material at different temperatures and durations of thermal treatment. The theoretical analysis of experimental data indicates that the high-temperature thermal purification of alumina is well described by the Arrhenius-type kinetic equation. Both the activation energy and pre-exponential factor of this process as a whole are retrieved from the laboratory experiments. A comparison with the experimental data showed that theoretical predictions based on the simplest one-stage sublimation model are acceptable for potential engineering estimates of the remaining impurities at rather different thermal regimes of high-temperature treatment. The latter is expected to be useful to optimize the industrial production of pure alumina.