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:
May. 13, 1997
Filed:
Dec. 13, 1995
Jean Deville, Aix-en-Provence, FR;
Jean-Michel Lamerant, Bouc Bel Air, FR;
Aluminium Pechiney, Courbevoie, FR;
Abstract
A process for eliminating iron from supersaturated sodium aluminate solutions obtained from the alkaline attack according to the Bayer process of the monohydrate bauxite including successively the steps of grinding and eventually of desilicatation in the presence of an aliquot of decomposed liquor, then attack at a temperature higher than 200.degree. C., usually between 240.degree. and 270.degree. C., of the said crushed and eventually desilicatated bauxite by the remaining fraction of the decomposed liquor, to make the alumina hydrate soluble and to form at the end of the attack an insoluble suspension of the residue or red mud in the supersaturated sodium aluminate liquor which, after cooling and dilution, is decanted to separate the mud or insoluble residues from the supersaturated liquor destined to be decomposed in the presence of seeds after filtration, characterized by the fact that at the end of the attack, during the cooling of the suspension achieved by decreasing the pressure in the reactors, one injects in the said suspension at a temperature higher than 140.degree. C. a small quantity of a mixture containing calcium.