Patent ID: 6555077
Filing Date: 2003-04-29
Classification: C01F

Abstract:
A process for the removal of organic impurities from a Bayer process liquor, comprising:feeding a first liquor stream including organic impurities to a wet oxidation process to produce a first processed liquor which is depleted in organic compounds, but enriched with sodium carbonate and/or sodium oxalate; reacting sodium compounds with at least one of an aluminum oxide, an aluminum hydroxide, an iron oxide and an iron hydroxide in a feed slurry fed to a dry oxidation process, wherein at least part of the sodium compounds react in the dry oxidation process to produce a processed discharge product; feeding at least a first portion of the first processed liquor to a leach tank to which is added the processed discharge product from the dry oxidation process, wherein the sodium carbonate and/or sodium oxalate precipitate in the leach tank to form precipitated products; and separating the precipitated products from the leach tank and recycling the precipitated products to form at least part of the feed slurry fed to the dry oxidation process; wherein organic impurities in the first liquor stream and residual organic impurities remaining in the first processed liquor or in the recycled precipitated products are causticised to sodium aluminate or sodium ferrate in the dry oxidation process.