SU1212948A1 - Method of producing sodium nitrate - Google Patents

Description

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The invention relates to i: technology of inorganic substances, in particular to the preparation of sodium nitrate, which can be used in the chemical industry and in the production of mineral fertilizers.

The purpose of the invention is to improve the degree of processing of raw materials and reduce corrosion of technological equipment.

Example 1. A 25 h solid sodium bicarbonate was loaded onto a sieve tray. First, the bicarbonate is treated at 25 C with a low-concentrated nitrous gas containing O, 113% by volume of nitrogen oxides at oxidation state Ы ,, 57 Support the gas feed rate of 7.4 l / min. The process is carried out until the breakthrough of nitrous gases with a nitrogen oxide content of 0.005 06. % as determined by gas analysis. The change in the composition of the solid products, the non-hazardous gases after the column and the degree of nitrogen oxide trapping over time are presented in Table. one.

The resulting solid residue at 25 ° C is contacted in the column with highly concentrated nitrous gases s containing 30.0 vol.% Of nitrogen oxides with the degree of oxidation. The gas feed rate is maintained at 0.36 L / min. The process is carried out until complete conversion of sodium hydrogen carbonate into sodium nitrate, which is determined analytically by the composition of the product.

In tab. 2 shows the change in the composition of solid products over time, I

From the calculations of material, balance on the specified sequence of interaction of sodium bicarbonate and nitrous gases, it follows that the overall utilization of nitrogen oxides at two stages is 98.1%. From the data table. 1, a; but., That the content of oxides in contact with low-concentrated nitrous gases does not exceed the sanitary norms (0.005% by volume) in the conversion of gcd sodium carbonate by 12j5% o

Example 2: A 25 g column of crystalline gi, crocarbo sodium, and sodium are added to a loading column. Initially, the bicarbonate is in contact with nitrous gases containing 0.5% by volume of nitrogen oxides at a degree of oxidation of 58%.

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. gas 6 l / min. The process is carried out until the content of nitrogen oxides on the exhaust is slightly higher than 0.005% by volume. Data on the process are presented in table 3.

5 The obtained solid residue when contacted in a column with highly concentrated nitrous gases containing 7% by volume of nitrogen oxides with a degree of oxidation of 93%

and the gas feed rate in the pot is maintained at 0.5 l / min. The contact of nitrous gases with sodium bicarbonate is continued until the sodium bicarbonate is reduced to sodium nitrate with a bone. Table 4 shows the change in the composition of solid products in. of time. From the calculations of the material balance it follows that the overall utilization of oxides

 L nitrogen at the two stages of interaction is 98.6%.

From the data table. 3, it can be seen that the content of nitrogen oxides after the column GJ: o is suppressant within the limits of sanitary 25 v.w.y. norms in the conversion of sodium bicarbonate to 11.18%.

Example 3 25 g of solid sodium bicarbonate are loaded onto a column. In the beginning it is treated with

gr 15 With a low concentration nitrous gas containing 0.01 vol%, nitrogen oxides at a degree of oxidation of 72%, the gas feed rate is maintained at 5.6 l / min. Process

. lead to slip of nitrogen oxides

Many sanitary standards. Changes in the composition of solid products, nitrous gases after the column and the degree of nitrogen oxide trapping with

,,, over time is presented in Table. five.

The resulting solid residue at 15 ° C contacts the column with highly concentrated gases containing 2% by volume of nitrogen oxides with an oxidation degree of 68%,

The gas feed rate is maintained at 1.33 L / min. The process is carried out until complete conversion of sodium bicarbonate to sodium nitrate. Table 6 shows the change in the composition of solid products over time.

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From the calculations of the material balance at the indicated interaction of hydro-SS sodium carbonate and nitrous gases, it follows that the overall utilization rate of nitrogen oxides at two stages of conversion is 95j, 6%.

From the data table. 5 it follows that the content of nitrogen oxides reaches after the column the sanitary norms in the conversion of sodium bicarbonate by 10.72%.

From the above examples (Tables 1, 3 and 5) it can be seen that when contacting with fresh sodium bicarbonate, from low-concentrated nitrous gases with an oxide content of 0.01-0.5% by volume, nitrogen oxides are extracted from the gas with a high degree of completeness. Their concentration at the outlet of the column does not exceed the sanitary norms (0.005% by volume) if the degree of conversion of bicarbonate to nitrite and sodium nitrate does not exceed respectively 10.0 and 12.0%. From these data it follows that nitrous gases with a lower content of nitrogen oxides than 0.01% by volume react with the bicarbonate practically. However, it is impractical to use such gases to produce sodium nitrate, since the reaction rate drops significantly, a small amount of nitrogen oxides is used in the process, and the duration of the process will greatly increase to 40 hours (Table 5).

Higher concentrations of nitrogen oxides than 0.5 vol.% In the reaction of fresh sodium bicarbonate with low-concentration nitrous gases lead to a rapid slip of nitrogen oxides above sanitary standards (Tables 1 and 3), which leads to a decrease in the use of nitrogen oxides and contamination occurs

them atmospheric air. one

From tab. 2, 4 and 6 it is clear that with

using highly concentrated nitrous gases with an oxides content of 2-30 vol% for complete conversion of residual sodium bicarbonate to sodium nitrate, the process lasts between 1-4 hours. When using nitrous gases with an oxide concentration of less than 2%, the conversion process of residual bicarbonate becomes long, more than 4 hours. The use of more concentrated nitrous gases, containing nitrogen oxides of more than 30% by volume, is not technologically feasible, since even when they are obtained from liquid dioxide Dimo dilution gas excess air to administration of oxygen for oxidation of the oxides

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nitrogen and nitrate production. At the indicated oxide concentration, an optimal 90% excess of oxygen in the nitrating gas mixture is created.

A temperature range of 15–30 s is chosen with the aim of simplifying the process and reducing corrosion in the gaseous environment that is obtained with a new nitrating agent (nitrogen oxides) (Table 7).

In the specified temperature range during the implementation of the process there is no need to either cool or heat as reacting components,

and the resulting reaction products. This simplifies the process. From the point of view of corrosion processes at More low temperatures than 15 ° C, they would slow down in this environment. However, this would lead to the need for forced cooling of the equipment and, therefore, to complicate the process.

Data characterizing the corrosion resistance of metals and alloys are given in table. 7

J, .. -.

From the data table. 7 shows that the process of nitration with oxides

nitrogen at 15-30 C instead of vapor 50-65% nitric acid significantly reduce the corrosion of equipment.

The advantages of using the proposed method in comparison with the known method is that when using nitrogen oxides as the nitrating agent and carrying out the process of contacting the bicarbonate first with low concentrated and then with high concentrated nitrous ra3aNni, the degree of using the nitrating agent increases from 91.4% to 95.6 -98.6%. In addition, conducting the process with crystalline solid bicarbonate and gaseous nitrogen oxides, obtaining sodium nitrate as a crystalline solid, lowering the temperature to 15-30 0 greatly simplifies the process compared to using a nitrating agent in the form of nitric acid vapors and obtaining the product in the melt, when it is necessary to underpin 305-350 s. However, the replacement of the nitrating agent with nitrogen oxides reduces the aggressiveness of the environment and, together with a decrease in temperature, leads to a decrease in

corrosion equipment. Moreover, the use of low concentrated nitrous gases in contact with fresh sodium bicarbonate allows the use of tail nitrous gases at this stage.

99.9 94.2 89.48 87.30

0.00 3.12 6.95 7.00

0.0 2.55 3.35 5.60

utilization of nitrogen oxides from them and at the same time their sanitary cleaning. Decrease. 5, the temperature of the process leads to a significant reduction in energy consumption.

Table 1

100 99, J 98, i

table 2

Table 3

Time h

The composition of the solid phase, wt.%

Table 4

Table 5

Table 6

Carbon steel 20-boil

ten

 Order 716/31 Circulation 452 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

. Fshgaal ShSh Patent, Uzhgorod, st. Project, 4

Table

20-100

0.1-0.73

Claims (2)

1. METHOD FOR PRODUCING SODIUM NITRATE by reacting sodium hydrogen carbonate with a nitrating agent, characterized in that, in order to increase the degree of processing of feedstock and reduce corrosion of technological equipment, nitrous gases are used as a nitrating agent, and the reaction is carried out first with nitroen gas, containing 0.01-0.5 vol.% nitrogen oxides, and then with nitrous gas containing 2-30% nitrogen oxides. 2. The method of pop. 1, with the fact that in the beginning the interaction leads to the total formation of 10-12% sodium nitrate and nitrite. uh u hU 00