CS199088B1 - Process for preparing liquid fertilizers - Google Patents

Description

The invention relates to the production of liquid fertilizers based on urea and ammonium dicalate (fertilizers of the DAM type). Fertilizer is produced from starting solutions using mother liquors from the production of 1,5-endomethylene-3,7- dinitroso-1,3,5,7-tetraazooyclooctane, also known as N, N-dinitrosopentamethylenetetramine, to prepare the urea solution. (dNTP were used). The ammonium dicalate solution aa is prepared by neutralizing nitric acid with ammonia in the usual manner.

For the industrial production of Ν, Ν-dinitrosopentamethylenetetramine, the most economically economical aspect is the nitrosating cleavage of hexamethylenetetramine. A combination of a mineral acid and an alkali metal nitrite or calcium nitrite is almost exclusively used as the source of the nitrosating agent. The reaction by-products remaining in the reaction mixture (i.e. in the mother liquor) after the isolation of the N, N-dinitrosopentamethylenetetramine are, in particular, the corresponding inorganic salt, formaldehyde, ammonium ions, and some excess nitrite is also present. When the reaction is terminated by neutralizing the large reaction mixture with alkaline hydroxide, the mother liquors from the production of N, U-dinitrosopentamethylenetetramine and hexamethylenetetramine, polyols and other formation and N-Mannich condensation products, as well as nucleophilic N nitroso products, are included. The use of mother liquors from the production of N, N-dinitrosopentamethylenetetramine using nitric acid and sodium nitrite has not yet been described, or

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199 098 potassium nitrite or calcium nitrite as a source of nitrosating agent.

The present invention solves the production of liquid fertilizers using mother liquors from the production of N, β-dinitrosopentamethylenetetramine by adding nitric acid from the mother liquors to remove nitrite present while acidolysis of the hexamethylenetetramine present and free formaldehyde is then added to the urea-formaldehyde by addition of urea. condensates. The amount of nitric acid for nitrite decomposition is chosen so that the pH of the mother liquors after acidification is 2.2 to 1.0. The decomposition of nitrites and hexamethylenetetramine is terminated by refluxing the acidified mother liquors. The mother liquors thus treated can be used directly as a urea solvent or, after addition of only a small amount of solid urea - at least 7 moles per mole of formaldehyde present can be thickened to 45% of the original weight without passing formaldehyde into the distillate. The thickened mother liquors can then also be used as a urea solvent. The resulting urea solutions are then used to prepare a liquid fertilizer based on the urea-ammonium nitrate complex.

The process of producing liquid fertilizers using mother liquors from the production of N, β-dinitrosopentamethylenetetramine has not been described in the literature to date. Treatment of the mother liquors within the meaning of the present invention will eliminate the toxicity due to the decomposition of the nitrites present and the conversion of the formaldehyde present to biologically harmless urea-formaldehyde condensates. The resulting urea solutions are then used to produce liquid nitrogen fertilizers. The production of liquid fertilizers using mother liquors from the If, t-dinitrosopentamethylene tetramine production according to the present invention solves the environmental issues associated with the production of N, N-dinitrosopentamethylene tetramine and at the same time utilizes waste nitrates for plant nutrition.

Example 1

Mother liquors from the production of dinitrosopentamethylenetetramine with nitric acid and sodium nitrite as source of nitrosating agent were used for treatment. These lyes contained in 1000 milliliters:

6.06 g sodium hydroxide 11.10 g sodium nitrite

2.52 g hexamethylenetetramine 12.92 g formaldehyde

173.75 g of salts

The chemical oxygen demand was 26,032 mg oxygen per 1,000 ml.

These lyes were acidified with 65% nitric acid to pH > 2 and after 10 min boiling the salts were cooled to room temperature for analysis. Found in 1000 ml of treated liquors »

14.12 g of nitric acid

14.40 g of formaldehyde

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170.60 g of sodium nitrate

The mother liquors thus treated are used as a urea solvent.

Example 2

A 71.94% urea solution was prepared from the treated mother liquors of Example 1 and solid urea at 75-80 ° C. 980 g of this solution were mixed with 1110 g of 79.73% by weight ammonium nitrate solution at 75-80 ° C. Upon cooling to 20 ° 0, a liquid fertilizer with a density of 1.322 g.om ^-3 resulted in low pH = 7.8 after ammonia gas ammoniaization.

Composition of the product thus obtained ·

2.04% sodium nitrate 0.08% methylene groups

33.73% urea

42.44% ammonium nitrate

0.07% free ammonia 21.64% water

The nitrogen content in theory = 30.96% by weight

Determined nitrogen content = 30.40% by weight

Long-term storage of the product at -0.5 to +2.0 ° C did not cause salting out, the fertilizer remained liquid, clear.

Example 3

The mother liquors from the production of dinitrosopentamethylenetetramine with nitric acid and sodium nitrite as source of nitrosoone reagent were used for treatment. 1 000 milliliters of the following alkaline solutions:

16.25 g sodium nitrite 2.55 g hexamethylenetetramine

11.63 g of formaldehyde 139.71 g of salts of pH of the liquor was 6.5 and their chemical oxygen demand was 39 278 mg of oxygen per 1000 ml.

The lyes were acidified with about 65% nitric acid to pH = 2.2 and then refluxed for 20 minutes. After cooling to room temperature, analysis in 1000 ml determined:

6.58 g nitric acid 14.50 g formaldehyde 138.25 g sodium nitrate

The mother liquors thus treated, which mail at 20 ^{0 a} density of 1.095 g.cm ³ , were used as a urea solvent.

Example 4

A 65.03% solution was prepared from the treated mother liquors of Example 2 and solid urea at 70-75 ° C. 920 g of this solution were mixed with 835 g of an 89.82% ammonium nitrate solution at 80-90 ° C. Upon cooling to 20 ° C, a liquid fertilizer with a density of 1.341 g.cnT ³ resulted, which after ammonia gas ammonia had little pH = 7.6.

Composition of the product obtained:

2.41% sodium nitrate 0.12% methylene groups

35.56% urea

43.29% ammonium nitrate

0.04% free ammonia

18.60% water

Nitrogen content theoretically = 32,15%

Determined nitrogen content = 31.77%

Long-term storage of the product at -0.5 to +2.0 ° C resulted in salting out, the fertilizer remained liquid, clear.

Example 5

Mother liquors from the production of dinitrosopentamethylenetetramine with nitric acid and sodium nitrite as source of nitrosating agent were used for treatment. 1 000 milliliters of these alkalis with low composition:

2.24 g sodium hydroxide 12.58 g sodium nitrite

4.68 g of hexamethylenetetramine

10.60 g of formaldehyde

154.44 g of salts

The chemical oxygen demand was 29,559 mg of oxygen per 1,000 ml.

The liquors were acidified with 65% nitric acid to pH = 1 and then refluxed for 10 minutes. After cooling to 20 ° C, the composition revealed a composition of 1000 ml lyes:

25.14 g of nitric acid 16.88 g of formaldehyde

143.60 g sodium nitrate

The mother liquors thus treated, which had a density of 1.09 g / cm @ 2 at 20 DEG C., were used after concentration as a urea solvent.

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Example 6

131 g of treated mother liquors according to Example 5 were heated to 80 ° C and after addition of 41.2 g urea (i.e. 10.18 moles of urea per mole formaldehyde) the solution was heated to 80-85 ° C for 15 minutes. After this time, when the solution no longer contained free formaldehyde, 72.2 g of water were distilled off in vacuo (i.e., the concentration was converted to 44.9% of the float weight of the treated mother liquors).

Example 7

To the concentrated mother liquors of Example 6, 211.3 g of urea was added at 85-90 ° C, and the solution thus obtained was mixed with 451.5 g of a 69.93% ammonium nitrate solution having a free ammonia content of 0.04. % by weight. After cooling to 20 ° C, the low-yielding fertilizer had a density of 1.355 g / cm @ 2 and a pH = 7.4. Composition of the product obtained:

2.26% sodium nitrate 0.12% methylene groups

33.11% urea

41.88% ammonium nitrate

0.02% free ammonia 22.61% water

Nitrogen content theoretically = 30,48%

Determined nitrogen content = 30.07%

Long-term storage of the product at -0.5 to +2.0 ° C did not result in salting out, the fertilizer remained liquid, clear.

Example 8

The mother liquors from the production of dinitrosopentamethylenetetramine with nitric acid β calcium nitrite as the source of nitrosoone reagent were used for treatment. 1 000 milliliters of the following alkaline solutions:

1.60 g sodium hydroxide 17.96 g calcium nitrite

133.33 g of calcium nitrate 0.32 g of hexamethylenetetramine

21.71 g of formaldehyde

The chemical oxygen demand was 24,048 mg of oxygen per 1,000 ml.

These liquors were acidified to pH 2 to 1 with 65% nitric acid followed by reflux for 10 minutes. After cooling to 20 ° C, the composition revealed a composition of 1000 ml of conditioned liquors:

24.92 g of nitric acid

20.40 g of formaldehyde

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155.65 g calcium nitrate

3.40 g of sodium nitrate

The mother liquors so treated, which mail a density at 20 ° C of 1,116 g.cm ^, were concentrated and then used as a urea solvent.

Example 9

To 196.3 g of treated mother liquors according to Example 8, heated to 70 ° C, 50-urea (i.e. 7 mol of urea per 1 mol of formaldehyde) was added. After heating the solution at 90-95 ° C for 5 minutes, 86.6 g of water were distilled off in vacuo, the solution was concentrated to 55.87% of the original weight of the mother liquors treated.

Example 10

To the concentrated mother liquors (108 g) of Example 9 was added 93.8 g urea and the mixture was heated to 75 ° C until the urea was almost completely dissolved. To the resulting urea solution was added 215.6 g of an ammonium nitrate solution with a concentration of 79.77% by weight and a free ammonia content of 0.28% by weight. Upon cooling to 20 [deg.] C., the fertilizer results in a low density of 1.388 g.cnT- ³ and pH 4.9. After ammonia gas ammonia was pH = 8.1.

Composition of the product obtained:

6.47% calcium nitrate 0.40% methylene groups 0.14% sodium nitrate

34.50% urea

42.43% ammonium nitrate

0.11% free ammonia 15.95% water

Nitrogen content in theory »32.16%

Nitrogen content determined at 32.01%

Storage at a temperature of -0.5 to +2.0 ° C resulted in precipitation of salt crystals after 30 hours. These crystals occupied about one third of the flood volume of fertilizer, the liquid above the crystals was clear.

Example 11

For treatment ea they used mother liquors from the production of dinitrosopentamethylenetetramine with nitric acid and potassium nitrite as a source of nitrosating agent. 1 000 milliliters of the following alkaline solutions:

24.22 g potassium nitrite 229.20 g potassium nitrate

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23.22 g of formaldehyde pH of the liquor was 4.5 and the chemical oxygen demand of 25,642 mg of oxygen per 1,000 ml.

These liquors were acidified to pH = 2.2 with about 10% nitric acid and refluxed for 10 minutes. After cooling to 20 ° C, the composition revealed a composition of 1,000 milliliters of lye:

13.20 g nitric acid 20.80 g formaldehyde

250,60 g of potassium nitrate

The mother liquors thus treated, which had a density of 1.130 g.cm < -1 > at 20 [deg.] C., were concentrated and then used as a urea solvent.

Example 12

To 174.2 g of the treated mother liquors of Example 11 heated to 80 ° C were added 54.6 g of urea and after heating to 80-85 ° C for three minutes, when free formaldehyde was no longer present in the solution, vacuum distilled off. 37.5 g of water.

Example 13

209.3 g of urea were added to the concentrated mother liquors of Example 12 and the mixture was heated to 75-80 °. To this mixture was added a 87.67% ammonium nitrate solution of 352.8 g. After cooling to 20 ° C, the obtained fertilizer was araoniaked with ammonia gas to pH >8.4; the resulting product at 20 ° C had a density of 1.330 g.om ³ .

Composition of the product obtained:

5.10% potassium nitrate 0.20% methylene groups

34.86% urea

41.53% ammonium nitrate

0.26% free ammonia 18.05% water

Nitrogen content theoretically = 31,73%

Determined nitrogen content = 31.69%

When stored at a temperature range of -0.5 to +2.0 ° C, a slight crystallization occurred after 80 hours and was not changed by further storage.

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Example 14

To 1000 g of liquid fertilizer according to Example 4 was, for the purpose of adjusting the content of nitrogen, added 32 ml matečnýoh liquor prepared according to Example 3. The resultant fertilizer slightly at 20 ° C a density of 1.329 g.orn ^- N, pH = 7.3. Composition of the product obtained:

2.76% sodium nitrate 0.14% methylene groups

34.36% urea

41.85% ammonium nitrate 0.03% free ammonia

20.85% water

Nitrogen content theoretically = 30,90%

Steady nitrogen content «30,49%

Long-term storage of the product in the temperature range of -0.5 to +2.0 ° C did not cause salting out, the fertilizer remained liquid, clear.

Claims (2)

A process for the production of liquid urea-ammonium nitrate fertilizers from starter solutions, characterized in that the mother liquors derive from the production of 1,5-endomethylan-3,7-dinitroso-1,3,5,7-tetraazocyclooctane by nitrosative cleavage of hexamethylenetetramine with nitric acid and alkali metal nitrites or calcium nitrite is acidified with nitric acid to pH 1.0 to 2.2, then refluxed for 20 minutes, and after the addition of urea in an amount of 7 to 35 moles per mole of formaldehyde present, for min. The mixture is heated to 70 to 95 ° C for 3 minutes, the solution thus prepared is made up to 65 to 81% urea concentration and then mixed with a 65 to 90% ammonium nitrate solution in a weight ratio of 1.0: 1.2, preferably in a weight ratio of 1.0: 0.9 to 1.0: 1.1. 2. The process for producing liquid fertilizers according to claim 1, characterized in that the treated mother liquors according to claim 1 are concentrated to up to 44.9% by weight.