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1. WO1996019410 - METHOD FOR THE REMOVAL OF IRON FROM SODIUM ALUMINATE LIQUORS RESULTING FROM ALKALINE ATTACK ON ALUMINA-MONOHYDRATE-CONTAINING BAUXITE

Publication Number WO/1996/019410
Publication Date 27.06.1996
International Application No. PCT/FR1995/001703
International Filing Date 20.12.1995
IPC
C01F 7/06 2006.01
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
FCOMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE EARTH METALS
7Compounds of aluminium
02Aluminium oxide; Aluminium hydroxide; Aluminates
04Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
06by treating aluminous minerals with alkali hydroxide
C01F 7/47 2006.01
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
FCOMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE EARTH METALS
7Compounds of aluminium
02Aluminium oxide; Aluminium hydroxide; Aluminates
46Purification of aluminium oxide, aluminium hydroxide or aluminates
47of aluminates
CPC
C01F 7/062
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
FCOMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
7Compounds of aluminium
02Aluminium oxide; Aluminium hydroxide; Aluminates
04Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
06by treating aluminous minerals ; or waste-like raw materials; with alkali hydroxide ; , e.g. leaching of bauxite according to the Bayer process
062Digestion
C01F 7/0633
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
FCOMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
7Compounds of aluminium
02Aluminium oxide; Aluminium hydroxide; Aluminates
04Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
06by treating aluminous minerals ; or waste-like raw materials; with alkali hydroxide ; , e.g. leaching of bauxite according to the Bayer process
062Digestion
0633characterised by the use of additives
C01F 7/47
CCHEMISTRY; METALLURGY
01INORGANIC CHEMISTRY
FCOMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
7Compounds of aluminium
02Aluminium oxide; Aluminium hydroxide; Aluminates
46Purification of aluminium oxide, aluminium hydroxide or aluminates
47of aluminates ; , e.g. removal of compounds of Si, Fe, Ga or of organic compounds from Bayer process liquors
Applicants
  • ALUMINIUM PECHINEY [FR]/[FR]
Inventors
  • DEVILLE, Jean
  • LAMERANT, Jean-Michel
Agents
  • LATARD, Jean-Marie
Priority Data
94/1572722.12.1994FR
Publication Language French (FR)
Filing Language French (FR)
Designated States
Title
(EN) METHOD FOR THE REMOVAL OF IRON FROM SODIUM ALUMINATE LIQUORS RESULTING FROM ALKALINE ATTACK ON ALUMINA-MONOHYDRATE-CONTAINING BAUXITE
(FR) PROCEDE D'ELIMINATION DU FER DANS LES LIQUEURS D'ALUMINATE DE SODIUM ISSUES DE L'ATTAQUE ALCALINE DE BAUXITE A MONOHYDRATE D'ALUMINE
Abstract
(EN)
Method of removing iron from supersaturated sodium aluminate solutions resulting from alkaline attack by the Bayer method of treating alumina-monohydrate-containing bauxite. The method comprises the successive steps of grinding and optionally desilicating, in the presence of a decomposed liquor fraction, and then attacking at a temperature above 200 °C, generally 240 - 270 °C, said ground bauxite possibly desilicated by the remaining decomposed liquor fraction, in order to solubilize the aluminate hydrate and form after the attack a suspension of insoluble residue or red mud in the sodium aluminate supersaturated liquor. After cooling and dilution, said supersaturated liquor is decanted to separate the mud or insoluble residue from the supersaturated liquor, which after filtering is decomposed in the presence of a seed. The invention is characterized in that, after attack and during cooling of the suspension by the gradual reduction of pressure in the reactors, a small quantity of a calcium-containing compound is introduced into the suspension at a temperature exceeding 140 °C.
(FR)
Procédé d'élimination du fer dans les solutions d'aluminate de sodium sursaturées issues de l'attaque alcaline selon le procédé Bayer de bauxite à monohydrate d'alumine, comportant successivement les étapes de broyage, éventuellement de dessilicatation en présence d'une aliquote de liqueur décomposée, puis d'attaque à une température supérieure à 200 °C, comprise généralement entre 240 et 270 °C de ladite bauxite broyée et éventuellement dessilicatée par la fraction restante de la liqueur décomposée, pour solubiliser l'hydrate d'aluminate et former en fin d'attaque une suspension du résidu insoluble ou boues rouges dans la liqueur sursaturée d'aluminate de sodium qui, après refroidissement et dilution, est décantée pour séparer les boues ou résidu insoluble de la liqueur sursaturée destinée après filtration à être décomposée en présence d'amorce caractérisé en ce qu'en fin d'attaque, au cours du refroidissement de la suspension par abaissement progressif de la pression dans les réacteurs, on injecte dans ladite suspension à une température supérieure à 140 °C une petite quantité d'un composé contenant du calcium.
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