The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 31, 1985
Filed:
Jun. 08, 1984
Chiyoda Chemical Engineering & Construction Co., Ltd., Yokohama, JP;
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. The improvement is in the first stage, comprising the steps of: (a) providing an aqueous slurry containing seed aluminum hydroxide and (b) mixing a pH controlling agent with the aqueous slurry to adjust the pH of the aqueous slurry to a value less than 5 or more than 11 and to dissolve fine crystallites of aluminum hydroxide contained in the aqueous slurry, the pH controlling agent being substantially free of ions which can form a precipitate during the first step, and then (c) then mixing an alumina compound with the aqueous slurry to adjust the pH of the aqueous slurry to a value in the range of from 6 to 11 and to cause the seed aluminum hydroxide to grow, the steps (b) and (c) being repeated in sequence more than once so that the seed aluminum hydroxide is caused to grow into the alumina hydrogel.