RU1838240C - Method of preparing aluminium hydroxide for calcination - Google Patents

Abstract

Usage: in the technology of alumina production. SUBSTANCE: aluminum hydroxide is separated from aluminate solution. Hydrophobizing agents treated with monochromatic coherent radiation are introduced into the pulp at the last washing stage. The pulp is filtered. The resulting aluminum hydroxide is dried and calcined. 3 tab.

Description

The invention relates to non-ferrous metallurgy and can be used in alumina production technology

The purpose of the invention is to reduce energy consumption.

To obtain monochromatic coherent radiation, an LG-38 helium-neon laser was used, which emits light with a wavelength of 0.63 microns.

With the introduction of hydrophobizing substances pre-irradiated for 5-30 seconds into the aqueous hydrated pulp, the moisture content of the cake is further reduced by 0.6-2.9% abs, which corresponded to an increase in the degree of dehydration by 9.2-18.6% and a decrease in the energy consumption for external evaporation moisture and calcining at 26.6-69.8 kJ / t.

The following were used as hydrophobizing substances: a mixture of 1.2-1.5 pentadiols; 1,4,5 - pendatriols and their polymers (substance No. 1); condensation product of cyclohexanol - bottoms in the rectification of raw cyclohexane and contains

10% cyclohexanol and cyclohexanone (substance 2); dialkyl dithiocarbamoylmethylphosphonic acid dialkyl esters (substance 3).

Example 1. In an aqueous suspension of the hydrate of the Volkhov Aluminum Plant (W: T 2: 1) 20 - 25 ° С, an additive of organic hydrophobizing substance No. 1 was introduced, which was previously irradiated with monochromatic coregent radiation for 5 - 25 s. The pulp was stirred for 3 minutes, then transferred to a Buchner funnel and filtered. The results of the experiments are given in table 1.

PRI me R 2. In the aqueous suspension of the hydrate of the Volkhov aluminum plant, substance No. 2 trained for 5-30 s was introduced under the conditions of Example 1.

The results of the experiments are given in table.2.

Sample The substance No. 3 irradiated for 5-30 s was introduced into the aqueous suspension of the hydrate of the Volkhov Aluminum Plant under the conditions of Example 1. The experimental results are shown in Table 3.

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Irradiation of hydrophobic substances less than 5 s does not improve the performance of the process of dehydration of aluminum hydroxide during filtration, more than 20 s is impractical due to the excess consumption of radiation energy,

As follows from the data in the tables, when organic hydrophobic substances are preliminarily irradiated with monochromatic coherent radiation for 5–20 s when introduced into the aqueous hydrated pulp: the moisture content of the cake is further reduced by 1.0–2.9% abs .; the degree of dehydration is increased by 9.2-18.6%; energy consumption is reduced by 187.1- 904.4.103 kJ / t.

Using the proposed method for preparing aluminum hydroxide before calcination provides the following advantages over the existing one: the possibility of reducing the residual moisture content of aluminum hydroxide after filtration without preliminary drying; the possibility of an additional increase in the degree of dehydration of aluminum hydroxide due to the activation of the hydrophobizing properties of organic

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substances by irradiation with monochromatic coherent radiation; the possibility of reducing heat consumption for drying and calcination.

The proposed method for the preparation of aluminum hydroxide by introducing an irradiated water-repellent substance at the last stage of filtration before calcination can be carried out using technological equipment used in alumina production.

Claims (1)

SUMMARY OF THE INVENTION A method for preparing aluminum hydroxide for calcination, comprising separating aluminum hydroxide from an aluminate solution, introducing substances hydrophobizing the surface of aluminum hydroxide into a water pulp in the last washing step, filtering and pre-drying before calcining, characterized in that, in order to reduce energy consumption , substances hydrophobizing the surface of aluminum hydroxide are treated with monochromatic coherent radiation before being introduced into the aqueous pulp. Table 1 table 2 Table 3