Patent ID: 7658896
Filing Date: 2010-02-09
Classification: C01F

Abstract:
1. In a Bayer process for the treatment of bauxite by alkaline digestion, said Bayer process treatment comprising the steps of treating bauxite ore with a hot, aqueous solution containing sodium hydroxide to obtain a supersaturated solution of sodium aluminate, separating undigested ore residue from the supersaturated solution, seeding the supersaturated sodium aluminate solution after said separation with particles of alumina trihydrate to cause precipitation of alumina trihydrate, and to obtain a depleted sodium aluminate solution designated spent liquor, and recycling the spent liquor to the step of treating bauxite ore, the improvement comprising removing an aliquot of the spent liquor, heating the aliquot of spent liquor, mixing the heated aliquot of spent liquor with ground bauxite to form a slurry, and returning the slurry to the treating step, wherein the heating step comprises heating the aliquot of spent liquor to a temperature sufficient that first contact between the ground bauxite and the spent liquor occurs at a temperature of greater than about 95° C., and that after said mixing step, the slurry is at a temperature greater than about 95° C.