Abstract: High molecular weight organic compounds, such as humic acid derivatives, are removed from Bayer process caustic liquors by oxidation of these compounds. The process involves addition of oxygen to the caustic liquor in quantities in the range established by the solubility of the oxygen in the liquor under the oxidation conditions.

Abstract: Bayer process liquors derived from the digestion of bauxites with a caustic solution are purified by removing at least a portion of the organic impurities present in the liquors. Removal of these impurities is accomplished by treating liquor containing dispersed therein solids generated by the Bayer process or added thereto, such as red mud particles, alumina trihydrate, oxalate salt, or filter aid with an organic polymeric, water-soluble cationic quaternary ammonium salt (POLYQUAT salt) which due to its cationic nature will adhere to the surface of the dispersed solids. The organic coating or layer adhered to the solids provides a receptive surface for the organic impurities, thus allowing formation of a solid-Polyquat-organic Adduct which is easily removed from the Bayer system.

Abstract: Bayer process caustic liquors are purified by treating the liquors with an organic solvent of relatively low boiling point, such as methanol, which causes the precipitation of inorganic carbonate and/or sulfate salt from the treated liquor. The treating solvent can be readily recovered for reuse.