Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group iiia metal or beryllium
Patent
1990-05-29
1992-06-16
Lewis, Michael
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group iiia metal or beryllium
423127, 423625, 423121, C01F 702
Patent
active
051223490
ABSTRACT:
An improvement in the process for extracting alumina from gibbsitic bauxites, wherein the basic, known process comprises mixing the bauxites with a sodium hydroxide-sodium aluminate digestion liquor, digesting the bauxites at a temperature in the range of 100.degree.-180.degree. C., diluting the resulting slurry, separating the red mud therefrom, precipitating alumina hydrate by cooling and agitation of the sodium aluminate liquor, and calcining the alumina hydrate precipitate to obtain alumina, wherein the improvement is characterized by so controlling the process that, in the liquid phase of the slurry leaving the digestion reactor, the reactive hydroxide ion concentration is maintained below 6 g/l, and preferably between 0 and 2 g/l, where the reactive hydroxide ion concentration is defined by the following formula: ##EQU1## where: C.sub.Al.sbsb.2 O.sub.3,gi.sup.eq is the equilibrium solubility of Al.sub.2 O.sub.3 for gibbsite, in g/l.
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Banvolgyi Gyorgy
Csordas T. Anna
Feher Ivan
Ferenczi Tibor
Sajo Istvan
Aluminiumipari Troszt
Bos Steven
Lewis Michael
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