SU1082779A1 - Method for producing complex fertilizer - Google Patents

Abstract

1. A METHOD OF OBTAINING A COMPLEX FERTILIZER, including neutralizing phosphoric acid with ammonia, drying and granulating the resulting pulp in the presence of an acid neutralizing agent, adding the amount necessary to achieve an ipH of the granulated mixture of 3.5-4.8, O tl, and so that, in order to reduce ammonia losses and increase the yield of the finished product, the pulp is mixed with an acid neutralizing agent before granulation and granulation is carried out when spraying at a pressure of 0.5–4 atm. p. 1, about tl and h and y y i and y0 so that as TBE acidic agent takes sulfuric, nitric and / or phosphoric acid. 3. Method according to paragraphs. 1 and 2, that is, with the fact that an ammonium phosphate pulp with a concentration of 76-95% and a pH of 5.5-7.0 is fed to the displacement, and the displacement is carried out at 95-125С for 0, 1-30 s.

Description

The invention relates to a method for producing ammonium phosphate fertilizers widely used in agriculture.

There is a known method for producing fertilizer, according to which phosphoric acid is neutralized with ammonia to a pH of 5.5-6.0, followed by crystallization of the product with the addition of phosphoric acid at this stage in an amount necessary to achieve a pH of 4.0-4.5. The concentration of the pulp entering crystallization is 86-88%. The moisture content of the finished product is 6-9% {1.

However, according to this method, the product is obtained in a practically powdered form with high humidity, the subsequent granulation of which will require the addition of binders and the drying of the substance and granulation in separate apparatuses, due to clumping of the duct, which significantly complicates the process.

The closest to the proposed technical essence and the achieved result is a method for producing fertilizers, including neutralization of phosphoric acid with ammonia, essence and granulation of the pulp in the presence of an acid neutralizing agent added in the amount necessary to achieve the pH of the granulated mixture 3 | 5--4, 2 According to this method, ammonium phosphate pulp is taken as the acidic neutralizing agent, KOTOpjoo is added at the granulation stage 2.

The disadvantage of this method is the significant loss of ammonia during cjrnnce of the product, amounting to 4-15% of the injected, as well as the low yield of the finished product about 40%.

The purpose of the invention is to reduce ammonia losses and increase the yield of the finished product.

The goal is achieved in that according to the method of obtaining a complex fertilizer, including neutralizing phosphoric acid with ammonia, the substance and granulation of the resulting pulp in the presence of an acid neutralizing agent, added in an amount necessary to achieve a pH of the granulated mixture of 3.5-4.8, Before granulation, the pulp is mixed with an acid neutralizing agent, and the granulation is carried out by spraying at a pressure of 0.5-4 atm.

It is advisable to take sulfuric, nitric and / or phosphoric acid as an acidic agent.

Preferably, the mixture is fed with ammonium phosphate pulp with a concentration of 76-95% and a pH of 5.5-7.0, and the mixing is carried out at 95-125С for 0.1-30 s.

The method is carried out as follows.

Phosphate pulp having a pH of 5.5-7.0 and concentration is mixed with an acid neutralizing agent, for example phosphoric acid containing 50-54% PjOj,

The acidity (pH) of the pulp and its concentration are chosen so that the pulp has mobility sufficient for technological purposes. The mobility of the pulp, in turn, is determined by the solubility of ammonium phosphates, which depends on the value of E.

A change in the pH of the same pulp from 4.0 to 8.0 first leads to an increase in solubility, and then to a slight decrease (Table 1).

Table 1

As dido from tab. 1, the maximum solubility falls on the pH range of 5.5-7.0, in which it is possible to obtain phosphate pulp with a concentration of 75-90%, which significantly improves the technical and economic indicators of the drying process. However, granulation and drying of the specified pulp in the BGS apparatus leads to a significant loss of ammonia, and also affects the quality of the finished product, which reduces the yield of the finished product. For ammonia and ammonia and to increase the yield of the product while maintaining the high concentration used; pulp, an acidic neutralizing agent is introduced into the phosphate pulp before granulation. If sour neutralizing

the agent is administered for granulation, i.e. If the phosphate and acidic agents are fed in separate streams, the alkali product (phosphate per pulp) gets into the hot granules and ammonia is lost in the granulation and pigging stages. When an acidic agent is supplied to the phosphate pulp, excess ammonia reacts with hydrogen ion by an acidic agent before graying.

f

+ H Ht

Nz

The mixture of pulp and hydrogen-containing-i-containing component is carried out in the liquid phase, since the crystallized product practically does not adhere to the surface of the granules and the granulation mode is disturbed - small substandard particles are formed. Due to the fact that crystallization of the mixture using concentrated components on sneaking through 0.1 to 30 s, is after mixing, it is advisable to mix the components in the form of two sprayed streams directed at an angle of 0-90 ° each at, pressure 0, 5-4 atm. The amount of the acidic neutralized component introduced is chosen so that the pH of the mixture to be granulated and, therefore, the final product is in the range 3.5-4.8. The selection of the indicated pH range is explained below. At pH below 3.5 in. the finished product contains free acid, drastically reducing the physicochemical and agrochemical properties of the product, and at a pH of more than 4.8, the loss of ammonia during drying increases.

Spray pressure, atm

0.3

The conditions of the experiments, the results of which are given in table. 2: ammonium phosphate pulp pH 6.0, concentration 80%, neutralization} sludge agent - sulfuric acid with a concentration of 93%. The acidity of the mixture corresponds to pH 4.5.

As vidzh) from tabl. 2, there is a sharp. the change in the yield of the finished product with a decrease in pressure below 0.5 atm (the product pelletizes, more than 60% (particles larger than 4 mm are inserted) and with an increase in pressure above 4.0 atm, fine fines form (45% of the product is dust).

The selectivity of the feed to the mixing of ammonium phosphate with a concentration of 76-95% is explained as follows.

With a decrease in the pulp concentration below 76% due to an increase in humidity,

Ammonia loss.

The output of the finished product.

1.6

37

power consumption. An increase in the pulp concentration above 95% is impossible due to the loss of the technological properties of the pulp (mobility) ..

An important role in the process of displacing the reactants is played by the mixing temperature. Thus, at a temperature below, crystallization of the pulp occurs, and at a temperature above 125 ° C, the equipment is corroded.

Example 1. 1000 kg of phosphoric acid with a concentration of 37% neutralize 130 kg of ammonia. The resulting pulp having a concentration of 76% and a pH of 5.8, I is mixed in a nozzle with 250 kg of phosphoric acid concentration of 52%. Slicing is carried out for 0.1 s at 95 ° C. The resulting mixture is sprayed with compressed. In addition, when the reaction (I) proceeds, an additional amount of heat is emitted, ifotoporo evaporates the moisture contained in the pulp, which allows increasing equipment productivity while reducing fuel consumption. The appropriateness of the selected process intervals is explained as follows. The mixing time of the pulp with the acid neutralizing agent is determined by the concentration of the reagent, the nature of the acidic agent, and the mixing conditions. When the contact time of the streams is less than 0.1 s, the mixture does not averaging, which negatively affects the granulation process and leads to ammonia losses, and at the contact time of more than 30 seconds, the reaction mass crystallizes, the equipment goes out of order and the granules are broken. . 2 illustrates the feasibility of selecting the pressure when spraying the resulting mixture. Table 2 51 with air at a pressure of 3 atm. The pH of the mixture is 4.1. Spraying occurs in the volume of the drying drum granulator (BGS). At the same time, 315 kg of retur and hot coolant are simultaneously removed. T After drying, 945 kg (75%) of the finished product is crawling. ,%: PjOsycB 52.5; P105Water 49.7; N 11.3. Fuel consumption per ton of finished product is 41 kg ut. The loss of ammonia at suias is 1.7 g / m. Example m 2. 1000 kg of phosphoric acid at 47% neutralize 220 kg of ammonia. You will get a pulp having a concentration of 89.7% and a pH of .6.6, mixed with 360 kg of azopecian acid with a concentration of 70%. Mixed for 30 seconds at 125 ° C, pH 3.5. The resulting CMe (% is sprayed at pressures and 0.5 atm. A 400 kg recharge and hot coolant is fed into the granulator of a torus-drynku.kad odinyurekushyu apparatus. After drying, 1072 kg (71) of the product is obtained with a yield of 0.6%) PjOs: N2 I: 0.4. Fuel consumption for the production of 1 ton of the finished product is 18 kg u. The pH of ammonia during drying is 0.5 g / m. Example 3 1000 kg of phosphoric acid 43% of the lots are neutralized with 130 kg of ammonia. The resulting pulp, which has a concentration of 82% and a pH of 5.5, is mixed with 60 to ° C of sulfuric acid of kolentra O1 of 93%. Mixing is carried out in for 3 s at 115 C. A mixture with a pH of 4.8 is sprayed at a pressure of 4 atm into the torso granule drum, where 270 kg of retur and hot test is introduced. After drying, 850 kg (76%) of the product of composition is obtained,%: PjOsycB 50.2; N3 12.5, moisture 0.7%. Fuel consumption during drying is 16 kg. Ammonia losses are 1.75 g / m. PRI me R 4. 1000 kg of phosphoric acid concentrate 37% neutralize 160 kg of ammonia. The resulting pulp, having a concentration of 78% and a pH of 7.0, is mixed with 380 kg of a mixture of acids containing 40.5% of PjOs and 10% of 8Oz. Mixing is carried out in a nozzle for 1 s at 100 ° C. A mixture with a pL of 3.9 is sprayed at a pressure of 2 atm into a tumble dryer-granulator where 330 kg of retour and hot heat carrier are simultaneously introduced. After drying, 1050 kg (78%) of the product of composition are obtained,%: PjOi 51.2; NZ 12.5, moisture 0.5%, fuel consumption is 32 kg ut per ton of product, ammonia loss is 0.6 g / m. The use of the proposed method allows to reduce ammonia losses from 4-15% from the injected to 1.7-1.8% and increase the yield of the stale product from 40 to 71-78%. In addition, the proposed method significantly reduces the fuel consumption required to obtain 1 ton of finished prod.

Claims (3)

1. METHOD FOR PRODUCING COMPLEX FERTILIZER, including neutralization of phosphoric acid with ammonia, drying and granulation of the obtained pulp in the presence of an acid neutralizing agent, added · in the amount necessary to achieve / pH of the granulated mixture equal to 3.5-4.8, characterized in that, in order to reduce ammonia losses and increase the yield of the finished product, the pulp is mixed with an acid neutralizing agent before granulation and granulation is carried out by spraying at a pressure of 0.5-4 atm. „. 2. The method according to π. 1, with the fact that sulfuric, nitric and / or phosphoric acids are taken as the acidic agent. 3. The method according to PP. 1 and 2, it is important that pulp of ammonium phosphates with a concentration of 76-95% and a pH of 5.5-7.0 is fed to the mixture, and mixing is carried out at 95-125 ° C in 0.1-30 s. cl ¹ / □ o N3 M 1 1082779