SU1472441A1 - Method of producing single-substituted barium phosphate - Google Patents

Abstract

The invention relates to the preparation of phosphate salts, in particular, the technology for producing monosubstituted barium phosphate, and can be used in optical glassmaking, phosphor technology, and laboratory practice. The aim of the invention is to increase the yield and quality of the product and reduce the process time. Monosubstituted barium phosphate is obtained by treating 80-85% phosphoric acid with an excess of 15-30% of stoichiometry with barium hydroxide at a temperature of minus 2-4 ° C, separating the product from the mother liquor by centrifuging, washing and drying the precipitate. The yield of the product is 62.3-76.2% for barium hydroxide, the content of the basic substance in the product is 99.5-99.8%, the processing time is 0.5-1.0 hours. 3 tab.

Description

one

The invention relates to the preparation of phosphorus salts, in particular, to the technology for producing monosubstituted phosphate of barium, and can be used in optical glassmaking, in phosphor technology, in laboratory practice.

The purpose of the invention is to increase the yield and quality of the product and reduce the process time.

Example 1. In a reactor equipped with a mechanical stirrer and a thermometer, 76 g of 85% phosphoric acid, taken with a 20% excess of stoichiometry, are introduced. 90 g of barium hydroxide are added in portions

(47% BaO). The reaction is carried out with stirring for 30 minutes, maintaining the temperature at the same time. The resulting precipitate is separated from the mother liquor - and washed with acetone, taken in an amount of 100 ml. Then the phosphoric acid monosubstituted barium crystals are squeezed in a centrifuge and dried in a drying cabinet at 75 ° C. The result is 69 g of the finished product. The product yield is 76.2%. The content of the main substance in it is 99.8%.

According to a known method, barium phosphoric acid monosubstituted is obtained by treating 70% phosphoric acid.

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four;

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taken with a 50% excess of stoichiometry, with barium hydroxide (47% BaO) at a temperature not above and stirring the reaction medium for 5-6 hours. The resulting product crystals are separated in a centrifuge, washed with alcohol and dried at 70-80 ° C The product contains 98% of the basic substance; its yield is 51.7% for barium hydroxide.

Table 1 shows data on the effect of phosphoric acid concentration on the process performance (an excess of phosphoric acid — 20% of crekHo-metry, processing temperature).

Table 1

taking into account barium ions. Therefore, the content of the main substance is more than 100%, indicating an excess of barium ions in the product, i.e. for the presence of mesi

Table 2 presents data on the effect of excess phosphoric acid.

0 on the process performance (concentration of phosphoric acid - .85%, processing temperature -3 С).

From the data of Table 2 it follows that with a decrease in the norm of phosphoric acid below 15%, the content of the basic substance decreases and the duration of the process increases due to the partial hydrolysis of the single-substituted phosphate barium with a lack of acidic medium. With an increase in the amount of phosphoric acid, the reaction is slowed down due to the coating of the barium hydroxide particles with a phosphate film, to prevent which 5 intensive mixing and a longer time is required.

The content of the basic substance decreases with an increase in the excess of phosphoric acid due to the impurity of free acidity.

0

From the data table, 1 it follows that

at phosphoric acid concentrations below 80% and above. 85% of monosubstituted phosphate of barium in solutions of phosphoric acid is hydrolyzed to form dibarium phosphate. With

acid concentrations below 80% form poorly permeable crusts of dibarium phosphate, which impede the diffusion of acid to the solid surface of barium hydroxide particles. Process time

increases and product yield decreases. With concentrations and x acids more than 85%, the viscosity of the solution increases, which reduces the speed of the process, as well as the yield of the product.

The method for analyzing the mass fraction of barium phosphoric acid monosubstituted was carried out according to the established standards specified in TU-6-09-1112-76 according to which the barium phosphoric acid monosubstituted content is calculated in percent, taking into account the mass conversion rate of BaSOs by weight . those. only with

Table 2

 Since all the experiments were carried out under the same conditions, and the amount of acetone for washing the precipitate from phosphoric acid was taken the same thing, then this amount of acetone is not enough to remove from large excess acid, therefore the percentage of free

51

acid helps to reduce the quality of the product,

Table 3 presents data on the effect of the treatment temperature of phosphoric acid on the process performance (the concentration of phosphoric acid is 85%, the excess acid is 20%),

Table 3

From the data of Table 3 it follows that the optimal neutralization temperature is - (2-A) ° C.

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The use of lower temperatures, although it allows to obtain a pure product and intensify the process of its production, but it is not economically feasible.

As the temperature rises, after a very short period of time from the start of the reaction, a hard crust of the product is formed, which creates a large resistance to the diffusion of the acid, i.e., the content of the basic substance decreases.

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Claims (1)

Invention Formula 20 The method of producing barium phosphate of mono-substituted one, which involves the treatment of phosphoric acid with barium hydroxide followed by centrifuging the precipitate of the product from the mother liquor, washing the product and drying it, and so that, in order to increase the yield and product quality and reducing the process time by processing, take phosphoric acid with a concentration of 80-85 wt.%, with an excess of 15-30% of stoichiometry and processing n is carried out at a temperature of - (2-4) 0. s