Method for controlling sodium oxalate levels in sodium aluminate solutions

摘要

A process is described for removing sodium oxalate from a sodium aluminate liquor produced through bauxite digestion using the Bayer process. The novel sodium oxalate removal procedure comprises the steps of (a) continuously generating new and reactive seed particles of sodium oxalate by mixing together an aqueous solution of sodium oxalate and a portion of said Bayer process sodium aluminate liquor to achieve a concentration of sodium oxalate within a range to generate spheroidal particles of sodium oxalate (b) adding a suspension of said spheroidal particles of sodium oxalate as seed to a second portion of said Bayer process sodium aluminate liquor, to thereby precipitate the remainder of dissolved sodium oxalate and (c) separating the sodium oxalate precipitate, leaving a liquor of reduced sodium oxalate contamination. The spheroidal particles are formed by controlling the concentration of sodium oxalate at a level about 5 % to about 75 % above autonucleation concentration.