The process of manufacture of ammoniac saltpeter of heterogeneous reaction lies the interaction of gaseous ammonia with nitric acid solution

NH₃ + NGOS₃ = NH₄NO.₃ +Q

This reaction is virtually irreversible and flows at high speeds without formation of by-products. In the process of neutralizing stands out a lot of heat, defined reaction heat effect, the original concentration of nitric acid and temperature of the reagents..

Because the ultimate goal is to obtain the production of solid ammonium nitrate, then neutralize seek, possible, more concentrated solutions of ammonium nitrate, to further simplify and reduce evaporation stage solution to the condition of anhydrous plava. Optimal conditions for the process of neutralization are selected as a result of a joint analysis of the influence of the process parameters such, as the concentration of nitric acid, the temperature and pressure in the reactor. To obtain a highly concentrated solutions it is necessary to apply high-concentration nitric acid, Preheat reagents.

Thus, the parish of heat is determined by the quantity of heat, made by source components and excelling at interaction of these reagents. Heat process relegated formed solution of ammonium nitrate, lost in the surrounding Wednesday and spent on evaporation of water from a solution. With appropriate apparaturnom registration process heat of neutralization reaction can be enough to evaporate the water, input with nitric acid.

Heat of reaction from the reaction zone is essential not only to use for evaporation of the solution, but because, What temperature is too high leads to decomposition of nitric acid and ammonium nitrate produced.

The temperature in the area is dependent on the pressure neutralization, When the process, Therefore, in terms of the feasibility of lowering the temperature in the reaction zone, the process must be carried out under low pressure and even under vacuum. Therefore, the most widely distributed installation, in which the neutralization process is carried out under pressure close to atmospheric. Advantages: ease scheme, the possibility of using gaseous ammonia, that of ammonia production is granted under p = 200-300KPa, without compression and repeated evaporation and two-time use of neutralization heat.

Less economical vacuum neutralization process limited applied in installations, where the raw material used is not pure ammonia, and tank, and purge gases or gases of ammonia distillation production of urea. The neutralization process under pressure leads to a decrease in the size of the equipment and the acquisition of juice a couple with higher parameters. Neutralization system when r = 3-6at apply abroad, they require large energy consumption in ammonia compression, relatively sophisticated control pressure nitric acid, etc.

Industrial installations for obtaining solution of ammonium nitrate using heat of neutralization reactions are divided into 4 type:

1) installation, working at atmospheric pressure ((gauge). R = 0.3 at);

2) installation, operated by vacuum evaporator;

3) installation, working under high pressure;

4) combined installation, working under pressure in zone neutralization and dilution in the zone of separation of juice vapours from a solution of ammonium nitrate.

The most widely distributed 1-th scheme, It is simple and is stable mode of operation.

Neutralization process lead 110-135⁰With the slightly Wednesday, unnecessarily. ammonia losses, nitric acid and ammonium nitrate with juice pairs less, than in alkaline Wednesday.

Intensive conditions largely process can be ensured by design working apparatus. Neutralization reaction is carried out in continuous current device IOT (the use of heat of neutralization).

Evaporation of solutions of ammonium nitrate.

A sine qua non for improving the quality of the ammonium nitrate is ensuring a high degree of evaporation it solutions in evaporating devices with the achievement of water residue in finished product is not more than 0.3%. Depending on the method of crystallization product, design of evaporators solutions of ammonium nitrate to the State uparivaût plava different concentrations. So, When crystallization in granbašnâh solutions douparočnyh devices uparivaûtsâ concentration to 99.7%-99.9% of NH₄NO.₃. With increasing concentration of solutions of NH₄NO.₃ when their uparivanii solution temperature rises, and increasing losses of ammonium nitrate with Sokov ferry. So apply evaporators, Working dilution 550-600 mm Hg. St. This enables uparivat′ solutions at lower temperatures their boiling point, that helps to reduce losses of products at this stage of production.

For the evaporation of ammonium nitrate solutions often apply two-tier scheme of residues, rarer three-tier. Two-stage serves to spend so, in the first stage of concentration increased up to 84%, the second is to 99.5%.

Melt crystallization of ammonium nitrate (granulating).

Depending on the methods of crystallization plava ammonium nitrate can be obtained in the form of small partially fragmented crystals, in the form of dense scales and in the form of spherical granules (d = 2 mm). In obtaining salt from plava nitrate is allocated a considerable amount of heat due to the cooling of the melt, crystallization and recrystallization of salt. With increasing concentrations of ammonium nitrate heat quantity, excelling in the crystallization of salts, significantly reduced.

Crystallization of ammonium nitrate from her plavov is carried out in the Office with full use of heat process (caliculus type Crystallizer, augers), with partial use of heat (cooling drums-rollers) and without the use of heat (granulation Tower). In n in. There are three technological method of granulating solids of melts:

1) A spattering of molten droplets using various granulating device in the volume unit of prilling Tower, where further solidification occurs drops and cooling granules formed during their freefall.

2) Spraying plava, his further cooling and solidification of formed granules in fluidized bed conditions.

3) Carrying out the same, that and on the way 2 operations in spinning reels with internal blades-sferodajzerov.

Main industrial way is granulation melts in pelletizing towers. Granbašnâ-construction of the cylindrical form, D = 12 m, N = 39 m, made of reinforced concrete, inside lined with brick lining; the lower part of the Tower-bottom runs three truncated cones, between which there are ring gaps (slit) for air inleakage Tower and cleaning cones from nitrate. At the top of a tower installed granulator-conical basket, on the side of which is a few thousand holes of different diameters. On the ceiling are installed 3-4 fan, suction air from Tower. The air rises through the 28 Windows, located at the bottom of the Tower around the perimeter. In each tower provides visitors with 200-300 thousand. m³ air, which is at the exit of the Tower contains fine particles of ammonium nitrate. Drops plava, arising out of the holes of the pellet mill, falling from a height are washed by a cold stream of air and freezes, being formed into pellets, in doing so, they are dried slightly. The higher the concentration of plava and more intensive cooling it drops, the smaller pores and cracks formed granules and the higher their strength.

Temperature of granules of ammonium nitrate prilling Tower on leaving ranges from 80 to 150⁰With and depends on the specific load on the Tower, flow, the temperature of the cooling air, free fall height of granules and their size. So spend cooling granules in fluidized bed. This process is combined with dosuškoj, drawing on the surface of the granules of different substances. For the formation of a boiling layer enough, to the linear velocity of the sžižaûŝego agent (air) was 0.6-1.2 m/s, that is achieved by the use of conventional fans.

The ultimate stage in the process is the conditioning of fertilizer-surface treatment of granules of different additives (more often than not SAW) to prevent packing and ensure good flowability. Pellet processing SURFACTANT leads to hydrophobization of surface granules, that protects the product from the rapid moistening in contact with air, relative humidity above hydroscopic point of ammonium nitrate.

Product ammonium nitrate stored in one-storeyed fireproof warehouses at the rate of up to 20,000 tonne bulk or bagged 2500t in each room. Warehouse premises must be dry, equipped with ventilation and air heating. Floors lay of acidproof materials. Weight stacks of bags of ammonium nitrate must not exceed 700t, and the distance between stacks shall be not less than 3 m. Storage comply with measures, exclude ammonium nitrate pollution with various objects, lubrication and obtiročnymi materials, etc. Include not only temperature control incoming of ammonium nitrate, but inside the pile, as well as appropriate signage. Ammonium nitrate must not is in contact with substances, giving an alkaline or acidic reaction

The following figure shows the modern large-capacity unit producing ammonium nitrate Al-72 capacity 1360 t/d. The original 58-60 %-Naya nitric acid is heated in the heater up to 70-80° c Sokov ferry from apparatus IOT 3 and served to neutralize. Before the apparatus 3 the nitric acid phosphoric and sulphuric acid are added in such quantities, to the finished product contained 0,3-0,5% P₂In₅ and 0,05-0,2% ammonium sulphate.

The unit has two apparatus IOT, working in parallel. In addition to nitric acid, they serve a gaseous ammonia, in the preheated heater 2 steam condensate to 120-130° c. The number of applications submitted by nitric acid and ammonia thus regulate, to exit the apparatus IOT solution had a small excess acid (2-5 g/l), ensures the completeness of the absorption of ammonia.

At the bottom of the apparatus of the neutralization reaction occurs at a temperature of 155-170° c; which produces concentrated solution, containing 91-92% NH₄NO₃. At the top of the unit water vapor (the so-called juice pairs) laundered from the spray of ammonium nitrate and nitric acid vapour. Part heat juice pair is used to preheat nitric acid. Then juice pairs are sent for cleaning and emit into the atmosphere.

The sour solution of ammonium nitrate placed in donejtralizator 4, where comes the ammonia, necessary to interact with the rest of nitric acid. Then a solution serves in evaporator 5. The resulting melt, containing 99,7-99,8% nitrate, at 175° c passes the filter 21 and centrifugal submersible pump 20 served in a pressure tank 6, and then in the rectangular metal granulâcionnuû Tower 16.

At the top of the tower are granulators 7 and 8, in the lower part of which serves the air, refrigerated falling from above drops nitrate. During the fall of drops from a height of nitrate 50-55 when wrapping their air flow formed granules of fertilizer. Temperature of granules at the exit of the tower is equal to 90-110° c; hot pellets cooled in fluidized bed apparatus 15. This rectangular device, has three sections, and endowed with a grate with holes. Under the grate fans draw air; This creates a fluidized bed of pellets nitrate, coming on the conveyor from granulation Tower. After cooling, the air enters the granulâcionnuû Tower.

Ammonium nitrate granules conveyor 14 served on the processing of surface-active substances into a rotating drum. Then the finished fertilizer conveyor 12 refer to the packaging.

Air, leaving granulation Tower, dirty particles of ammonium nitrate, and juice pairs of converter and air-vapor mixture of evaporator neproreagirovavšij contain ammonia and nitric acid, as well as carried out particles of ammonium nitrate. To clean these threads at the top of the granulation tower are six concurrent leaching scrubbers poppet type 10, irrigated 20-30%-s ' solution of ammonium nitrate, which is pumped 18 from the collection 17. Part of this solution is the neutralizer washing steam juice IOT, and then about to a solution of ammonium nitrate, and, Therefore, is used to develop products. Purified air is sucked out of granulation Tower fan 9 and emitted into the atmosphere.