Process for producing aluminum oxide by bayer process

Abstract

The invention provides a method for producing alumina by Bayer process and relates to the method for producing alumina by adopting diaspore and by the Bayer process. The method is characterized in that unrefined solution produced by the Bayer process carries out carbonating decomposition; the carbonitation decomposition products are added into a self-evaporation system of dissolving-out slurry for thickening and dissolving out. In the method of the invention, a part of decomposing original solution is completely decomposed by carbonating method; aluminum hydroxide obtained after the decomposition is thickened and dissolved out for reducing alpha k in the decomposing original solution, so as to realize the aim of enhancing yield and product quality; the method has significant meaning to China in producing sand-shaped alumina with high yield by using a high concentration sodium aluminate solution of the diaspore. The method of the invention can most effectively reduce the alpha k in the decomposing original solution by the Bayer process, which is not only suitable for factories using a combination method, but also suitable for factories using the Bayer process; the method has simple technique, which does not increase the content of sediment silt and has low cost after selling and utilizing calcium carbonate residue.

Description

A method for producing alumina by Bayer process technical field The invention relates to a method for producing alumina by a Bayer process, relating to a method for producing alumina by adopting a diaspore Bayer process. Background technique At present, more than 80% of alumina in my country is produced by the Bayer process, but since the diaspore type bauxite is processed, the Nk concentration of the lye has been increased to 150g / l or even higher in order to improve the cycle efficiency. The αk of the decomposition stock solution is also relatively high, up to more than 1.6, which is very unfavorable for improving the decomposition rate and product quality, and as the grade of bauxite used decreases, the dissolution index deteriorates, and the impact of this factor will be more serious. The Bayer method stripping material will merge with the sintering method crude liquid and the sintering method carbon separation mother liquid deep carbon product will be concentrated and ...

AI Technical Summary

Problems solved by technology

At present, more than 80% of alumina in my country is produced by the Bayer process, but since the diaspore type bauxite is processed, the Nk concentration of the lye has been increased to 150g / l or even higher in order to improve the cycle efficiency. The αk of the decomposition stock solution is also relatively high, up to 1.6 or more, which is very unfavorable for improving the decomposition rate and product quality, and with the decrease of the bauxite grade used, the dissolution index deteriorates, and the influence of this factor will be more serious

The Bayer method stripping material will merge with the sintering method crude liquid and the sintering method carbon separation mother liquid deep carbon product will be concentrated and dissolved must be the combined method alumina plant, and the confluence ratio is limited, and the Bayer method decomposition raw liquid αk has a small decrease. Applicable to joint law factories only

After the Bayer method is used to dissolve the slurry, the ore is added to increase the concentration and the dissolution uses foreign gibbsite ore. The cost is high and the amount of mud is greatly increased.