Abstract: An improved method of preparing alumina, including a first stage in which an alumina hydrogel is formed from seed aluminum hydroxide, and a second stage in which the alumina hydrogel is processed for conversion into alumina.

Abstract: An improved process for the preparation of alumina, including forming an alumina hydrogel from aluminum hydroxide, and processing the alumina hydrogel into alumina. The improvement involves the alumina hydrogel forming step which is connected in the presence of sulfate ion and which comprises providing, in a reaction zone, an aqueous slurry containing seed aluminum hydroxide and having a pH of 6-11, and feeding to the reaction zone an aluminum compound and a pH controlling agent for mixing with the aqueous slurry while maintaining the aqueous slurry at a temperature of at least about 50.degree. C. at feed rates so that the pH of the aqueous slurry is maintained within the range of 6-11 and that 0.2-5 mols/hour of aluminum components, in terms of elemental aluminum, are fed to the reaction zone per mole of the seed aluminum hydroxide originally contained in the aqueous slurry, whereby the seed aluminum hydroxide is caused to grow to the aluminum hydrogel.