Manufacturing method of alumina for raw materials for precision ceramics from kaolin

摘要

The present invention relates to a method for producing aluminas for precision ceramics from domestic low-grade kaolin, and a method for utilizing residue remaining after alumina extraction from kaolin as a rubber filler.;The production method of alumina from domestic low-grade kaolin is the reaction of kaolin with hydrochloric acid of about 26wt.% At about 105C, and aluminum component in kaolin is extracted into hydrochloric acid aqueous solution. The iron powder present as an impurity in the hydrochloric acid aqueous solution was removed by solvent extraction, and HCl gas was injected to obtain AlCl₃6H₂O.;A1C1₃6H₂O is pyrolyzed to obtain alumina and hydrochloric acid is recovered. In order to remove sodium contained in alumina, A1C1₃6H₂O was maintained at the HCl atmosphere during pyrolysis, and then the alumina produced was washed with water, pyrolyzed in air, and added with silicate to form sodium silicate.;A1C1₃6H₂O at a high temperature of 1200C or higher,₃To produce alumina having an alpha crystal size of 0.1-10.0 microns.;A method of manufacturing alumina for precision ceramics raw material from kaolin characterized in that the residue (silica as a main component) remaining after alumina extraction from kaolin is ground to 1 micron and used as a rubber filler to be used as a substitute for hard clay .