SU1225813A1 - Method of purifying sodium chloride solution - Google Patents

Description

This invention relates to the purification of waste sodium chloride solutions and can be used in various industries.

The purpose of the invention is to intensify the process by increasing the b sedimentation rate, and filtering the precipitate.

Example. Take 1 liter waste solution of sodium chloride composition, wt.%: CaGI 0.20; MgCl j 0.22; FeClj. 0.002; NaCI 0.64, 0.03 l of filtrate (1.0 wt.% From the spent NaGI solution) composition, wt.%: CaCO 0,0007; Mg (OH) 0.001; Ca (OH), 0.12; NaCl 1.12. The spent solution is treated with 54.5 ml of 2N. (0.1 shol. Units with respect to Ca from CaCI + Ca (OH),), 24 ml of Na-SiOj with a concentration of a solution of 5 g / l SiOj (40 mg SiO) and l of the spent solution), then the filtrate is poured and 69.5 MP 2 n. NaOH (1.0 stoich. Unit with respect to Mg from MgCI) and at ZO C the resulting suspension is clarified by settling, and the sedimentation rate of the suspension is 0.52 m / h.

The composition of the solid phase of the thickened suspension per 1 liter of solution, g / l: CaCl5 54.9; Mg (OH) j 40.6; Fe (OH) j 0.39; other 2.24, a total of 98.3.

The composition of the clarified brine, g / l: NaCi 11,2; Ca 0.003; Mg 0.004; Fe is missing.

0.2 wt.% Ca (OH) j is added to 100 ml of a thickened suspension and the resulting suspension is filtered, the filtration rate is 0.19 m / m h. The composition of the obtained filtrate, g / l: Ca (OH) 1.2 (0 , 12 wt.%); CaCOj 0.007; Mg (OH) jO, 01; no suspended solids; NaCl 11.2; Fe is absent 1.0 wt.% Of the filtrate (relative to the solution) is returned to the treatment step with the reactants, and the precipitate is removed to the dump.

Spreadsheets

The deposition rate (stars, m / h, with the introduction of the filtrate, nas.X About I 0.6 J 0.8 BO i .2 1.4 1 2.0 j 2.2 J. “.

The sequence of the introduction of reagents and filtrate

I

S

0

five

0

five

0

five

In tab. Table 1 shows the results of experiments to determine the sedimentation rate of the suspension after treatment with reagents of the spent NaCI solution without using Na in Table. 2 shows the results of experiments to determine the sedimentation rate of a suspension after treatment with reagents, a used solution of sodium chloride under conditions similar to those in Table. one.

The compositions of the spent sodium chloride solution and the filtrate, the dose of NaOH and the temperature are given in Example 1. The dose of sodium silicate is 20 mg / l SiO, j, / 1 l of the waste solution.

In tab. 3 shows data on the productivity of the result and the quality of the filtrate with different contents in the filtrate Ca (OH).

From the comparison of the results table. 1 and 2, it can be seen that the introduction of sodium silicate during the treatment of the spent sodium chloride solution significantly increases the sedimentation rate of the suspension.

As follows from the table. 2, the introduction of the reagents and filtrate in the processing stage of the treated NaCI solution in the following sequence: sodium carbonate card-1, sodium silicate, filtrate, caustic soda provides the maximum increase in the sedimentation rate of the suspension.

Using the proposed method makes it possible to purify waste solutions of sodium chloride from impurities of calcium, magnesium, and iron to reuse standards in the regeneration of ion exchange resins, to intensify the purification process by increasing the sedimentation rate by 2.5 times and the filtration rate of the suspension by 1.9 times.

The amount of Ca (OH introduced into the suspension before

by filtration,

Mac.ZO 0.08 0.12 0.1 0.20 0.25 0.30 0.35

Soderkakie

Ca (OH) in

filtrate

wt.X About 0.06 0.08 0.1 0.11 0.12 0, H 0.14 0.14

Valichna veve

cstv c. .

Muddy Muddy Muddy Muddy Muddy Muddy Lack-Lack-Lack-No-Loose

Performance by filter-. TU, 0.1 0.13 0.13 0.14 0.16-0.19 0.19 0.19

T blntz 2

Claims (1)

METHOD FOR CLEANING SODIUM OF CHLORIDE SODIUM from magnesium, calcium and sulfate ions * by treating the solution with caustic soda and sodium carbonate followed by separation of the precipitate formed by filtration, characterized in that, in order to intensify the process by increasing the deposition rate and sediment filtration, sodium silicate is additionally added to the solution processing stages, and before filtration, a solution of calcium hydroxide is introduced into the suspension until the content in the filtrate is 0.12 0.14 wt.% and then the filtrate is returned to the processing stage solution of reagents in an amount of 1-2 wt.% from the initial solution, while the reagents and the filtrate are introduced in the following sequence! sodium carbonate, sodium silicate, filtrate, caustic soda.