SU614026A1 - Method of obtaining ammonium nitrate - Google Patents

Description

one

The invention relates to a method for producing mineral fertilizers and can be used in the production of ammonium nitrate.

It is known that ammonium nitrate is obtained through the subsequent stages of neutralizing nitric acid with ammonia, concentrating the solution obtained by neutralizing and granulating a concentrated melt, including cooling the obtained granules, or crystallizing the same melt by known methods 1, 2, 3.

In the known methods, to obtain a high-quality product, it is necessary to obtain a concentration of 99.8-99.9 wt. ° / o.

This concentration of the melt, separated in a separate stage, was carried out by contacting the heated heat carrier air with the neutralizing solution obtained from ammonia), nitrous salt concentrate, which has a 94–96 ° / Cli concentration process of Hivieer ecto ter-logaz; a product that is more intense than its acidity. The amount of decomposition of the product reaches 0.5 ° / o, which leads to: loss of the raw material, in particular ammonia.

In addition, from the deadline, the participation of the Ju1i N the stage of the co-optrirovaniya. .itsits .1 ;; noo

the amount of saltpeter in the form of dust and aerosols, which causes no cleaning;

The closest to the proposed technical essence and the achieved effect is a method of obtaining ammonium nitrate by neutralizing nitric acid with ammonia, followed by concentration of the resulting solution, in which, to create a developed surface of phases during neutralization and new concentration of the resulting solution, additional air, ammonia are introduced into the reaction volume or their mixture 4.

When using the known technique, the concentration of ammonium nitrate solution can be increased only to 97.5%.

A further increase in the concentration of the melt requires additional heat input using a heat carrier, such as air, and does not exclude the aforementioned disadvantages, such as loss of ammonia and saltpeter and the need to clean the intermediate heat carrier air stream after the concentration stage.

The aim of the invention is to reduce losses of ammonia and ammonium nitrate and to simplify the process.

The goal is achieved by extracting MhiNi by the method of producing ammonium nitrate, which consists in neutralizing nitric acid.

ammonia, concentration of the resulting solution with the original ammonia, which is then fed to the neutralization stage, cooling and heating the resulting melt.

A distinctive feature of the process is the use of starting ammonia to concentrate a solution of ammonium nitrate.

The method is carried out as follows.

The preheated melting points of the melting effluent ammonia enter the heat and mass transfer zone, which is additionally heated by the coolant through the wall. A flowing solution of nitrate is moving towards the gaseous reactant. The water vapor released during the concentration process is absorbed by the ammonia, which then goes to neutralize the nitric acid, during which a solution of nitrate and juice are formed. Coming with ammonia to the stage of neutralizing water vapor contribute to the development of the contact surface of the phases of the interacting reagents and eliminate local overheating, causing decomposition of the nitrate. Neutralization can be carried out on failed plates or in the circulation circuit, and concentration in heated vertical pipes. The preferred temperature for preheating ammonia is 180-185 ° C, and the solution temperature is 175 ° C.

Example. 6390 kg of gaseous ammonia per hour at 180 ° C are fed against a flowing film of a solution of ammonium nitrate (33000 kg / h) with an initial concentration of ammonium nitrate of 91 wt.% And a temperature of 143 ° C. The concentration zone in height is heated with saturated water vapor at 190 ° C (pressure 12.8 atm).

The vapors released from the heated solution in the amount of 2630 kg / h are absorbed by hot ammonia gas (6390 kg / h). At the same time, the partial pressure of water vapor at the exit of the mass transfer zone at a mixture temperature of 160 ° C is 0.3 at (the pressure of saturated water vapor at 160 ° C is 6.3 at, the partial pressure of water vapor above the CNH4NO3 solution 91% at 146 ° C is 0.78 ata).

As a result, 30.0 t / h of melt of nitrate are obtained with a temperature of 175 ° C and a concentration of 99.8 w / o.

A gaseous mixture of superheated ammonia vapors and water at 160 ° C is supplied to neutralize a 56% aqueous solution of nitric acid, supplied in the amount of 41,500 kg / h at 90 ° C.

In the neutralization process, a solution of ammonium nitrate is formed in an amount of 33,000 kg / h with a concentration of 91 wt.% NH4NO3 at 146 ° C, which enters the mass exchange zone, and 17,900 kg / h of vapor vapor leaving the neutralization zone at lb5 ° C at pressure

1.05 ata.

The proposed method of obtaining ammonium nitrate will allow us to additionally produce about 5200 tons / year of the AC-67 mite nitrate production units using the AC-shortening losses of ammonia and ammonia seliger, and eliminating about 20000 purification from the process using the original ammonia. air that was used in the known method. Alkaline reaction

in the zone of concentration, it practically excludes the process of thermal decomposition even under the conditions of a concentrated temperature.

A preliminary economic calculation showed that the total cost reduction will be about 230 thousand rubles. per year per one unit for the production of am.monium nitrate AC-67 with a capacity of 450000 tons per year.

Claims (4)

1.Miniovich A.M. Production of ammonium nitrate. M., “Himi, p. 125 2. US patent number 3758277, cl. 23-285, 11.09.73. 3. The patent of France No. 1462280, cl. From 05 s, 5 16.12.67. 4. The patent of England No. 1105466, cl. C 1 A 06/06/68.