Process for the purification of aluminum hydroxide and process for the surface treatment of aluminum plate utilizing the purification process

摘要

The present invention allows the reproduction of a crystalline aluminum hydroxide having a high particle strength and a high purity which can find wide application such as abrasive from a supersaturated sodium aluminate solution which is being recycled in the production of aluminum hydroxide or lithographic printing plate. In a process for the purification of aluminum hydroxide which comprises the hydrolysis reaction of a supersaturated solution of sodium aluminate to crystallize aluminum hydroxide, the improvement which comprises the steps of keeping the temperature of a suspension formed by mixing a mother liquor having a total caustic soda concentration of from 50 to 700 g/l and an aluminum concentration or from 0 to 300 g/l with crystalline aluminum hydroxide at a range of from 10 DEG C. to 200 DEG C. for at least 1 to 48 hours, mixing the suspension with the supersaturated solution of sodium aluminate, and then causing the crystallization reaction at the crystallization reaction temperature.