Purification method of high-concentration sodium aluminate solution from Bayer process

Abstract

A purification method of a high-concentration sodium aluminate solution from a Bayer process comprises heating the high-concentration sodium aluminate solution to 80-120 DEG C, strongly mechanically stirring, adding a purifying agent into the sodium aluminate solution to desilicate and remove iron, organic substances and colored substances in the solution, and filtering to separate silica residue from insoluble substances to obtain the purified and decolorized sodium aluminate solution with absorbance lower than 0.30. The purifying agent is calcium oxide, magnesium oxide and / or calcined dolomite. The inventive method can perform deep desilication, remove iron and remove colored organic substances by one-step method.

Description

technical field [0001] The invention relates to a Bayer method for purifying a high-concentration sodium aluminate solution, which belongs to the field of light metal metallurgy, and specifically relates to a one-step deep desiliconization, iron removal and colored organic impurity removal method for a high-concentration sodium aluminate solution. Background technique [0002] During the production of Bayer process alumina, due to the alkali concentration in the sodium aluminate solution (Na 2 OK>150g / L), high concentration of alumina (Al 2 o 3 >165g / L), so the concentration of silica in the solution is high (SiO 2 >0.6g / L), high metastability, difficult to desiliconize. At the same time, after countless cycles of the sodium aluminate solution, various impurities may enter the mother liquor, and some impurities will accumulate in the sodium aluminate solution, which makes the composition of the sodium aluminate solution very complicated, and also makes the soluti...

AI Technical Summary

Problems solved by technology

[0011] The above methods are either for sintering sodium aluminate solution, because it does not contain organic matter, it is mainly for desiliconization and iron removal; or for lower concentration (Al 2 o 3 <100g / L) Bayer method sodium aluminate solution, and the removal of organic impurities and inorganic impurities silicon, iron, etc. in the solution is not considered comprehensively; and for high concentration Bayer method sodium aluminate solution, due to the high concentration of the solution , the structures of organic matter and inorganic impurities such as silicon become more complex when the concentration is low, so it is difficult to remove by conventional methods, and alkali concentration, alumina concentration, temperature, etc. will affect the desiliconization and decolorization effects

Therefore, in industrial production, for high-concentration sodium aluminate solutions, when the product requires particularly high whiteness, considering the economic cost, the above decolorization and purification methods cannot achieve the required effect