Patent ID: 6293973
Filing Date: 2001-09-25
Classification: C01F

Abstract:
A method of controlling the precipitation of soluble sodium oxalate in Bayer process liquor comprising the steps of:(a) adding a surface active quaternary ammonium compound to a Bayer process liquor to stabilize the sodium oxalate in the Bayer process liquor;(b) precipitating at least a portion of alumina trihydrate crystals from the Bayer process liquor;(c) subsequently adding a mixture of a hydrophobic oil and at least one surfactant to the Bayer process liquor to deactivate the stabilizing effect of the quaternary ammonium compound so that the sodium oxalate can be precipitated from the Bayer process liquor with the alumina trihydrate crystals; and(d) precipitating sodium oxalate for removal from the Bayer process liquor.