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Femipari Kutato Intezet

Aluterv Aluminiumipari Tervezo Vallalat

Almasfuzitoi Timfoldgyar

Ferenc Lazar

Karoly Solymar

Jozsef Matyasi

Tibor Ferenczi

Laszlo Lengyel

Istvan Voros

Peter Siklosi

Janos Zambo

Tihamer Pinter

Kalman Wentzely

Gyorgy Sigmond

Gyula Horvath

Jozsef Zoldi

Bela Toth

Jozsef Boros

Maria Orban Nee Kelemen

Ivan Feher

Pal Toth

Erno Bujdoso

Zoltan Ozvald

Marika Orban Nee Kelemen

The invention relates to an improved process for the production of alumina according to the Bayer technology, of bauxites containing goethite and especially of boehmitic or diasporic bauxites, for the acceleration of the digestion process, for the transformation of goethite into hematite, for the increase of alumina yield and for the reduction of the caustic soda losses, the essence of which consists in carrying out the digestion in the presence of 2-6% CaO and 0.2-2.0% Mg.sup.++, Fe.sup.++, Mn.sup.++ Co.sup.++ ions based on the weight of the dry bauxite or of compounds or ores containing these ions in the indicated quantities.

Process for digesting goethite-containing bauxites according to the

A method for processing bauxites according to the Bayer technology, with an increased yield in Al.sub.2 O.sub.3 and with decreased caustic soda losses, starting particularly from goethite bauxites of boehmite and/or diaspore type and carrying out the digestion at 180.degree.C to 300.degree.C using an aluminate liquor containing Na.sub.2 O.sub.caustic in a concentration of 80 to 300 g./l. The digestion is carried out in the presence of a calcium compound in an amount corresponding to 2 to 6 % of CaO calculated for the dry weight of bauxite and of a sulfate salt in an amount corresponding to 1.0 to 7.0 g./l. of sulfate ion concentration, whereby the goethite content of the bauxite is converted into hematite. The process provides advantageous conditions for the complete dissolution of the boehmite and diaspore content of bauxite in the vicinity of the equilibrium molar ratio, and enables to recover efficiently the caustic soda losses in the Bayer process itself, requiring no supplementary operation.

Method for processing bauxites

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Tatabanya, Hungary

Ferenc Lazar