| 摘要 |
A method for removing sodium oxalate from a caustic aluminate liquor produced using the Bayer process is disclosed which includes the steps of initially washing all the product aluminum trihydroxide obtained from the precipitation circuit to remove any crystalline sodium oxalate, thereby preventing any further sodium oxalate precipitation within the aluminum trihydroxide precipitators. This causes the dissolved sodium oxalate concentration to rise to a level which is conducive to economic removal of sodium oxalate by side-stream crystallization, without requiring a costly evaporation step. The sodium oxalate may be removed in an amount equal to the new sodium oxalate formed during fresh bauxite digestion, thus maintaining a steady dissolved concentration of sodium oxalate during aluminum trihydroxide precipitation. In addition, the aluminum trihydroxide precipitation circuit may further be stabilized in the crystalline oxalate-free condition by the addition of small amounts of an organic polymer.
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