PROCESS AND EQUIPMENT FOR PRODUCING ALUMINA

摘要

The production process comprises taking out an aqueous slurry containing seed alumina hydrate for effecting circulation, adding an aqueous solution of an aluminum salt and an aqueous solution of a neutralizing agent to the circulating aqueous slurry, mixing the resulting mixture at a pH of 6 to 11 to give an aqueous slurry containing alumina hydrate, and returning the formed slurry to the above slurry containing seed alumina hydrate. The production equipment is provided with a stirred vessel for accommodating the aqueous slurry and a circulator for taking out the aqueous slurry from the vessel for effecting circulation and returning the circulating slurry to the vessel. The section for returning the circulating slurry is provided with first and second units for adding, respectively, the aqueous solution of an aluminum salt and that of a neutralizing agent to the circulating slurry. The equipment is further provided with a mixer for mixing the circulating slurry with both the aqueous solutions. The invention provides porous alumina and porous composite oxides containing the same as the principal ingredient, in particular, an alumina carrier excellent as a carrier for hydrotreatment catalysts, which alumina has widely regulable pore distribution such as pore volume or pore diameter distribution, is excellent in producibility in spite of the simple production procedure, and can be formed into a molding with high mechanical strengths.