SU779370A1 - Method of sodium nitrate extraction from nitrate caustics - Google Patents

Description

one:

The invention relates to the production of nitrogen fertilizers and may be. used for the processing of lyes nitrate nitrate in the preparation of synthetic fatty acids using nitric acid, as well as the absorption of nitrous gases soda.

Sodium nitrate, containing impurities of mono- and dicarboxylic acids in a mixture with their sodium salts, as well as manganese salts, when used as a mineral fertilizer, provides an increase in sugar content, sugar beet roots, stimulates the germination of seed and the initial growth of plants.

A known method for the production of nitrate liquor as a raw material for the production of sodium nitrate by decomposing sodium soaps with nitric acid. However, this does not achieve the stability of the fertilizer composition, and the target product in its crystalline form contains significant amounts of iron compounds toxic for a number of agricultural crops.

Known methods for producing nitrogen fertilizers, including the stage of granulation of salts from l2j melts, lead to the decomposition of thermally unstable impurities of mono- and dicarboxylic acids and the reduction of nitrate forms of nitrogenous fertilizers to nitrite ones. .

It is also known that sodium nitrate is isolated from the nitrate liquor by evaporation under vacuum to a suspension, in which the total content of sodium nitrate is about 1 to 75%. One stripped off the solution, the temperature is 90-95 s, cooled to 40-45 s, and the precipitated crystals are separated from the mother liquor by centrifugation. Wet crystalline

15 salt is dried by air. Heat up to a temperature of 100 ° С 3j.

Along with the multistage process and the duration of the process, a significant disadvantage of the known special purpose plant is 20 to obtain sodium nitrate in crystalline form, which greatly limits its use as a mineral fertilizer for growing fodder and

25 sugar beets, as well as other agricultural crops. Labor productivity when applying granulated fertilizers to the soil increases 1.5-2 times compared with the use of crystalline forms of fertilizers.

The purpose of the invention is to intensify the process and obtain a granulated final product.

The goal is achieved by the fact that in the method of separation of sodium nitrate, 1 & key of cement evaporation into vacuum and the separation of the finished product, evaporation in vacuum leads to the moisture content of liquor 35-45%, after which the resulting solution is spray dried with a temperature of 400-700 s, supplied at a speed of 150–180 m / s, and sprayed sodium nitrate with a residual moisture content of 17–25% is granulated in a fluidized bed at 7–80 ° C. The fluidized bed velocity during granulation is 1.1-1.2 m / s.

The positive effect is achieved due to the high rate of dehydration of the sodium nitrate solution in the initial stage, which is provided by a significant heat exchange surface formed when the evaporated solution is dispersed by a heat transfer fluid moving at high speed, followed by the formation of granules in a fluidized bed. The temperature in the fluidized bed is much lower than in the flow of heat transfer fluid, which at this stage provides a low dewatering rate, which is necessary for the formation of granules of uniform composition, which have high mechanical strength. At the same time, contact of one stripped off sodium nitrate solution with the equipment is largely eliminated, which ensures a reduction in the iron content in the target product, while keeping in its composition modifying the additive mono and dicarboxylic acids.

Example. The nitrate liquor obtained from the decomposition of soap glue with nitric acid, the composition of%: sodium nitrate 16, carboxylic acids (mono- and dicarboxylic) 2.2 and manganese - 0.01, is subjected to evaporation under vacuum in a two-case evaporator until the residual moisture content is 40% . The evaporated solution at a temperature of 8 ° C is sprayed in a stream of air preheated to 550 ° C. Air velocity

in the spray zone of the evaporated solution is 160 m / s. The moisture content of sodium nitrate is reduced to 20% by intense evaporation. Sprayed, sodium nitrate is directed to a fluidized bed, the fluidization rate of which is 1.1 m / s. The temperature in the layer is maintained. The unloading and packing of the prepared product is carried out by known methods. The isolation of sodium nitrate from nitrate liquors after their preliminary evaporation is carried out using a spray boiling granulator dryer used in the chemical industry for the preparation of granulated ammophos. The material balance of the process of drying and granulation of one stripped off solution of sodium nitrate is given in Table. one.

composition and properties of sodium nitrate, isolated from nitrate alkali

0 production of synthetic fatty acids by the known and proposed methods are summarized in table. 2

As can be seen from the table, the proposed method provides higher quality indicators of the composition and mechanical properties of nitrogen fertilizer, sodium nitrate, compared with the known method.

0

The use of the proposed method of separating sodium nitrate from nitrate liquor provides, in comparison with the known following advantages: it significantly intensifies5 the process, by eliminating crystallization operations from the evaporated solution and separating the crystals from the mother liquor, the composition of the fertilizer - sodium nitrate remains mono and dicarboxylic acids and eliminated iron impurities; the target product is isolated in granular form with uniform particle size distribution and high granule strength, which allows

5 to improve the quality indicators and agrochemical properties of sodium nitrate, widely used in agriculture for the cultivation of fodder and dried beet.

Table 1

100 1764

60.0 1058 40.0 706

53.7 948.5

nit5,291.8 40.0 706.0

Total

100

1764

Claims (3)

1. A method for separating sodium nitrate from nitrate liquor, which includes evaporation in vacuum and isolation of the finished product, characterized in that, in order to intensify the process and obtain a granular final product, evaporation in vacuum is reduced to a moisture content of 35-45% lye, and then dried the resulting solution is sprayed with air at a temperature of 400-700s, supplied at a speed of 150-180 m / s, and sprayed sodium nitrate with a residual humidity of 17 Table 1 waste 0.1 1.7 losses 1.0 16.0 i-, ifi -iS - ii - - - iiiri i,: s 100 1764 table 2 25% granular in a fluidized bed at; 70-80 C. 2. The method according to claim 1, wherein the rate of the fluidized bed during granulation is 1.1-1.2 m / s. Sources of information taken into account in the examination 1.Wittka E. Modern fettechemishe Technologte. Heftt, 1940. 2. Patent IT 3690320, cl. 23-103, published. 09/12/72. 3. Klevke V.A. and others. Technologists 5 fertilizers, M., GHY, 1963, p. 105-110 (prototype).