Use of polymers in alumina precipitation in the Bayer process of bauxite beneficiation
AssigneeNalco Chemical Company
InventorsWilliam J. Roe, Jacqueline L. Perisho
Life of this patent
Estimating the term…
Abstract
The negative effects of sodium oxylate on the crystallization of aluminum trihydrate from Bayer process liquors may be eliminated or curtailed by adding an effective amount of a polyacrylic acid with a molecular weight about 1,000,000 and containing at least 50 mole percent acrylic acid monomer to pregnant Bayer process liquors.
Claims11
A method of reducing the percent alumina trihydrate crystals smaller than 200 micron in diameter, which crystals are produced during crystallization of alumina trihydrate from pregnant Bayer Process liquors contaminated with sodium oxalate, which comprises adding to the pregnant Bayer Process liquors, after red mud separation and immediately prior to crystallization of alumina trihydrate, an effective amount of a high molecular weight polyacrylic acid having a weight average molecular weight of at least one million and containing at least 50 mole percent acrylic acid monomer.
The method of removing sodium oxalate crystals from spent Bayer process liquors which comprises adding thereto in an effective amount for the purpose of agglomerating sodium oxalate crystals a high molecular weight polyacrylic acid having a weight average molecular weight of at least 1,000,000 and containing at least 50 mole percent acid monomer, and subsequently adding sodium oxalate crystallite seed crystals and cooling to a temperature sufficient to cause additional crystallization and precipitation of dissolved sodium oxalate from the spent Bayer process liquors.
Dependencies are inferred from the claim text.