PROCESS FOR THE CONVERSION OF GOETHITE CONTAINING BAUXITE

A method for processing bauxites according to the Bayer technology, with an increased yield in Al2O3 and with decreased caustic soda losses, starting particularly from goethite bauxites of boehmite and/or diaspore type and carrying out the digestion at 180 DEG C to 300 DEG C using an aluminate liquor containing Na2Ocaustic 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.