SU1659384A1 - Method of producing liquid nitrogen fertilizer - Google Patents

Abstract

The invention relates to a technique for producing liquid nitrogen fertilizer and contributes to its quality by removing the solid phase and increasing the nitrogen content in the fertilizer, as well as simultaneously producing pure chalk. According to the invention, calcium nitrate tetrahydrate is pretreated with ammonium carbonate solution to the ratio of calcium nitrate to ammonium nitrate in the liquid phase, equal to 0.3-1.4, followed by separation of the precipitate from the liquid phase and ammonization of the latter with gaseous ammonia to pH 7.5-12.0 with getting ready of the product. To simultaneously obtain pure chalk, a part of the liquid phase is treated with ammonium carbonate solution and filtered to form pure chalk in the solid phase. According to the proposed method, there is no solid phase in the liquid fertilizer, which contributes to its long-term storage at a content of 20-25% total nitrogen instead of 13-18% When kept for 5 months at room temperature and 1.5 months at (-5) and (-10) ° C, the resulting fertilizer does not undergo any changes. At the same time, the possibility of obtaining grained chalk. 2 tabl w

Description

The invention relates to a technique for producing liquid nitrogen fertilizer.

The purpose of the invention is to improve the quality of the fertilizer by removing the solid phase and increasing the nitrogen content in the fertilizer, as well as the simultaneous production of pure chalk.

The invention is illustrated by the following examples.

Example1.100 weight.h. Calcium nitrate melt, taken from the freezing stage in the production of complex mineral fertilizers, is mixed with 56.4 parts by weight. ammonium carbonate solution obtained by saturating ammonium nitrate solution with ammonia and carbon dioxide (36% - (MH4) 2CO3 34% - NH4N03, 30% - hfeO).

The mixture is kept for 30 minutes with constant stirring at 60 ° C. The suspension is filtered to obtain 77.4 weight hours of unwashed wet sludge and 79.0 per hour of filtrate.

The precipitate is washed with 26 weight h of water and sent for drying.

The filtrate is ammoniated with 5–0 weight parts of ammonia gas to a pH of 9.5 and 84.0 parts by weight are obtained. liquid fertilizer with a ratio of Ca (N03) 2.NH-qN03 0.6 salts. The obtained fertilizer does not contain a solid phase (3.5 wt.h according to the known), content% (Most - 16% according to the known), NF-5%.

Example 2 100 weight h, calcium nitrate melt taken from the freezing step

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mixed with 46 weight.h. ammonium carbonate solution obtained in this way. The mixture was incubated for 30 minutes with constant stirring at 60 ° C. The suspension is filtered out to obtain 66.0 parts by weight. wet unwashed sludge and 80.0 weight.h. filtrate with a ratio of Ca (N03) 2: NH4N03 0.8.

The precipitate is washed with 22 parts by weight. water and sent for drying

80.0 weight.h. the filtrate is mixed with 36.0 weight.h. ammonium carbonate solution. The mixture was kept in a thermostat for 30 minutes with constant stirring at 60 ° C. The suspension was filtered to obtain 33.0 parts by weight, wet, unwashed precipitate and 83.0 parts by weight. second filtrate, i.e. ammonium nitrate solution.

The precipitate is washed with 11 v, h, water and sent for drying. Sediment - pure chalk does not contain impurities: phosphates and fluorides of calcium, iron, silicon. The composition of pure chalk (99.5% - CaCO3).

PRI me R 3. 100 weight.h. Calcium nitrate melt, taken from the freezing stage in the production of complex fertilizers, is mixed with 51.5 hp. ammonium carbonate solution, also prepared as in example 1. The mixture was kept in a thermostat for 30 minutes with constant stirring at 60 ° C. The suspension is filtered out to obtain 71.5 ppm. wet unwashed sludge and 80.0 weight.h. filtrate with a ratio of Ca (N03) 2: NH4N03 0.7.

The precipitate is washed 24 weight, h. water and sent for drying.

40 weight.h. the filtrate is ammoniated 2.0 parts by weight, ammonia gas to pH 9.5 and 42.0 parts by weight are obtained. liquid fertilizer with the ratio of CA (MOZ) 2: MN4MOZ 0.7. The obtained fertilizer does not contain a solid phase (3.5 parts by weight - by known content: M0bsch.22% (16% by known content), MF 5.0%.

The remaining 40 weight.h, the filtrate is mixed with 20 weight.h. ammonium carbonate solution, obtained in the same way as in Example 1. The mixture was kept in a thermostat for 30 minutes with constant stirring at 60 ° C. The suspension is filtered out to obtain 13 weight.h. wet unwashed sludge and 47 weight.h. secondary filtrate.

The precipitate is washed 4 weight.h. water and sent for drying.

The liquid phase, which is a mixture of calcium nitrate tetrahydrate and ammonium nitrate solutions, is obtained by incomplete conversion of calcium nitrate tetrahydrate with ammonium carbonate solution, while the amount of ammonium carbonate varies from 30 to 70% of the stoichiometric standard required for complete conversion of tetrahydrate nitrate

calcium to obtain in the liquid phase the ratio of Ca (MOz) 2: MH4 0: 0.3-1.4.

Upon receipt of liquid fertilizer only, the liquid phase (total mass) is neutralized with ammonia gas to a pH of 7.5-12.0.

0 When only pure chalk is obtained, the liquid phase (whole mass) is treated with ammonium carbonate solution until complete conversion of the calcium nitrate contained in the liquid phase. The chalk is separated, washed for 5 seconds, dried.

When producing liquid fertilizer and chalk, the liquid phase is neutralized with gaseous ammonia to pH 7.5-12.0, the rest is treated with a solution

0 ammonium carbonate until complete conversion of the calcium nitrate contained in the liquid phase.

The processing of part or all of the mass of the liquid phase into fertilizer or chalk is determined by the five objectives and conditions of production.

An increase in the nitrogen content of the fertilizer is achieved by the formation of ammonia ammonium and calcium nitrate by neutralizing the mixture of solutions of tetra0 calcium nitrate hydrate and ammonium nitrate ammonia to pH 7.5–12.0.

The indicated ratio of Ca (MO3) 2: MN403 in the liquid phase after filtering the suspension is selected taking into account the content of total nitrogen in the liquid phase, the crystallization temperature, and is also determined by the complete purification of the liquid phase from impurities as a result of the conversion and filtration performance of the suspension.

0 In the table. 1 shows that with increasing degree of conversion, i.e., with decreasing Ca (NOs) 2: NH4N03 ratio in the liquid phase, the filtration performance increases due to accumulation in the sediment mass

5 calcium carbonate, which plays the role of a filtering pad for a fine gel-like sediment of impurities, increases the content of total nitrogen in the liquid phase by increasing the proportion of ammonium nitrate, the nitrogen content of which (35%) is greater than in calcium nitrate (17%), However, despite the advantages obtained by reducing the ratio of salts, it is impractical to carry out a conversion to obtain a liquid phase with a CafNOsh NhUNOs ratio below 0.3, since most of the calcium nitrate tetrahydrate is processed into contaminated impurities. I chalk. With an increase in the ratio of salts in the liquid phase, the temperature decreases

crystallization, however, obtaining a liquid phase with a ratio of Ca (NH3) 2: Mn403 above 1.4 is limited by the filtration stage. Suspension is practically not filtered because a significant proportion of the solid phase is composed of phosphorus, fluorine, silicon, which causes fine dispersion, helium draft. It is not possible to implement the filtration process under industrial conditions to obtain a liquid phase with a salt ratio above 1.4.

The proposed pH range from 7.5 to 12.0 liquid nitrogen fertilizer is determined by the content of total nitrogen and free ammonia c. fertilizer that is presented in table. 2, pH 7.5 is determined by the fact that the conversion process ends at pH 7.5-8.0. A further increase in pH due to the saturation of the liquid phase with ammonia increases the total nitrogen content and helps to reduce the crystallization temperature due to the formation of ammonia water with a crystallization temperature of 30 ° C. However, upon further saturation with ammonia to a pH above 12, the content of free ammonia increases dramatically, which leads to its loss during storage of liquid fertilizer and its introduction into the soil.

Therefore, the optimal interval

five

0

five

0

The scrap pH of liquid nitrogen fertilizer according to the proposed method is pH from 7.5 to 12.0.

According to the proposed method, there is no solid phase in the liquid fertilizer, which contributes to its long-term storage, with a content of 20-25% of total nitrogen instead of 13-18% of the known. When kept for 5 months at room temperature and 1.5 months at (-5) and (-10) ° C, the resulting fertilizer does not undergo any changes. At the same time, the possibility of obtaining pure chalk is created.

Claims (1)

Invention Formula The method of producing liquid nitrogen fertilizer, which includes neutralizing with ammonia gas a mixture of solutions of calcium nitrate and ammonium nitrate, is enough so that, in order to improve the quality of the fertilizer by removing the solid phase and increasing the nitrogen content, nitrate calcium is pretreated with a solution of ammonium carbonate to a mass ratio of starting calcium nitrate to ammonium nitrate in the liquid phase after pretreatment of 0.3-1.4, followed by separation of the precipitate from the liquid phase, and neutralizing the gas braznym ammonia is carried out until the pH 7,5-12.0. Table 1 table 2