SU1234365A1 - Method of purifying sodium chloride solutions - Google Patents

Description

The invention relates to methods for purifying sodium chloride solutions from potassium, calcium, and magnesium impurities and can be used in the production of chlorine and caustic soda by electrolysis and in the technology of producing soda water.

The goal of the acquisition is to intensify the process and simultaneously purify sodium chloride solutions from potassium.

Example. B2 of sodium chloride solution containing, g / l; NaCl 300; potassium 3; Calcium 3 was added 32 ml of 50% orthophosphoric acid (density 1.355 g / cm) and 72 ml of magnesium chloride solution (MgCl "BN.O) with a magnesium concentration of 150 g / l. The precipitation was carried out at fixed pH values 10, and vigorous stirring of the resulting suspension. The brine is filtered, and the purified brine is sent for clarification.

The content of impurities in the purified brine was: K 0.55 g / l; Ca 0.2 mg / l, Mg 0.1 mg / l; P0 150mg /

The pH value of the process of cleaning the solution of sodium chloride from potassium ions with respect to CajMg t: 3 and 20 С is as follows:

pH Content of potassium in purified brine, g / l

1.7

1.3 0.6

0.5 0.5 0.6 1.0

1J2.0

The effect of temperature on the content of residual potassium in the purified brine with the ratio Ca: Mg 1: 3 and pH is as follows:

Te / "Temperature, ° C Content of potassium

in purified brine, g / l

About 5

0.5 0.5

0.5 0.5 0.6 1.2 2.5

These data show that with an increase in the temperature of the solution over 25 ° C, the previously precipitated potassium is returned to the solution. The optimum temperature range is 5-25 ° C. Cleaning the brine at a temperature below 5 ° C is impractical because of a decrease in the rate of sludge sediment.

The effect of an excess of magnesium on the potassium content in the purified solution and on the rate of settling at pH 10 is given in the table.

The optimal range of excess magnesium with respect to calcium, which provides the required degree of purification of brines from potassium simultaneously with a high sedimentation rate, is 3-3.5.

Thus, the proposed method makes it possible to remove potassium from brine to the temperature of diaphragm electrolysis, increase the rate of sludge by 5 times, the rate of 11 h trash and 3 times, reduce the flow rate of the filter auxiliary in l rocha.

Claims (2)

METHOD FOR CLEANING SODIUM OF CHLORIDE SODIUM FROM CALCIUM, including treating it with alkali metal orthophosphate and then separating the precipitate formed, characterized in that, in order to intensify the process and simultaneously purify from potassium, the magnesium salt is introduced into the initial solution in an amount that provides a molar ratio of magnesium to calcium equal 3-3.5, and the treatment is carried out at a temperature of 5-25 ° C and a pH of 7.9-10.