Process for removing organic matter, iron and silicon dioxide in sodium aluminate solution

Abstract

The invention discloses a process for removing an organic matter, iron and silicon dioxide in a sodium aluminate solution. The process comprises the following steps: heating sodium aluminate circulating mother liquor to 80 to 90 DEG C, adding calcium oxide into the sodium aluminate circulating mother liquor for adsorption displacement reaction, the calcium oxide being obtained by calcining or precipitating pure limestones and calcining and crushing obtained calcium carbonate, performing stirring in an open state after addition to separate out the organic matter sodium humate in the solution in form of calcium salt, simultaneously reacting the calcium oxide with sodium aluminate in the solution to generate fine calcium aluminate particles with large surface areas, performing solid-liquid separation after reaction, filtering and separating small particles suspended in the solution after reaction, regulating the temperature of the solution to 45 to 55 DEG C, and adding 3 to 6 volume percent of hydrogen peroxide to further decolorize the solution, the treated mother liquor being used for preparing refined liquor. An operating flow is simple, no additional equipment is required, and the process is high in organic matter removal efficiency and low in cost, and has good impurity removal and decolorization effects and a broad application prospect.

Description

technical field [0001] The invention relates to the technical field of chemical impurity removal, in particular to a process for removing organic matter, iron and silicon dioxide in a sodium aluminate solution. Background technique [0002] Micropowder aluminum hydroxide has a particle size of 1-2 microns, regular shape, whiteness ≥ 95%, Fe 3 o 2 Content ≤ 1%, SiO 2 Content ≤ 2%, good dispersibility inorganic powder, mainly used for environmentally friendly flame retardant fillers, generally speaking, the preparation method is divided into mechanical method and chemical method, the mechanical method is through ball mill, vibrating mill, jet mill and other crushing equipment , so that the coarse-grained aluminum hydroxide particles are deformed and then broken, and finally become a fine powder with a particle size of 1-2. However, the product of this method has a wide particle size distribution and irregular shape, and the whiteness and purity of the product depend entirely...

AI Technical Summary

Problems solved by technology

[0003] Since the Bayer method dissolves bauxite to produce sodium aluminate circulating mother liquor, there are many impurities, so the purification process of sodium aluminate circulating mother liquor is required, and equipment and procedures are added. In order to simplify the production process of micropowder, the production of aluminum hydroxide micropowder mostly uses re-dissolved coarse-grained hydrogen Alumina is made into a saturated solution of sodium aluminate, and then crystal seeds are added by cooling and stirring to crystallize aluminum hydroxide to produce aluminum hydroxide micropowder. Since coarse aluminum hydroxide still contains a small amount of humic acid and ferrosilicon impurities, Repeated use of the alkali-dissolved mother liquor will cause the accumulation of organic matter, silicon dioxide, iron and other impurities in the solution, the composition of the solution will become complex, the solution will become viscous, and the color will appear dark brown, resulting in a reduction in the production capacity of aluminum hydroxide micropowder. Decreased quality, reduced product whiteness and purity, reddish-yellow color

[0004] The organic matter will cause the induced crystal seed to be poisoned by organic matter, and the activity will be reduced. At the same time, it will be adsorbed on the surface of the crystal nucleus, affecting the precipitation of aluminum hydroxide on the crystal nucleus, reducing the decomposition rate and grain growth rate, resulting in a decrease in the controllability of the particle size of the produced product , the particle size of the product is finer, and the filling performance is reduced

SiO 2 It will improve the stability of the solution, reduce the degree of supersaturation of the refined solution, and reduce the output rate

Fe 2 o 3 It will make the solution appear yellow and red, affecting the whiteness of the product