UA90250C2 - Method for the preparation of urea granulates, use of the compound of carboxylic acid, and also the use of the compound therein and solvent - Google Patents

Abstract

A method of improving the properties of urea granulates, more especially the caking tendency, the dast formation and the foaming tendency in aqueous media, by the addition of an additive to the urea, wherein the additive comprises a carboxylic acid compound with the general formula XY-(Z)-COOH, in which Z is a saturated or unsaturated hydrocarbon with 1-25 carbon atoms and X and Y are selected from the group consisting, of a hydrogen atom or a polar organic functional group, and in that the additive is added as a solution in a polar solvent to the urea granulates, which are subsequently dried.

Description

The invention relates to a method of improving the properties of urea granules, which are most relevant to the tendency to caking, dust formation and foaming characteristics in an aqueous environment, by introducing additives to urea.

Urea is widely used in many areas, such as the production of fertilizers, an ingredient for cattle feed, and the production of glue and melamine. Urea granules are produced mainly either by solidification of sprayed urea melt or by granulation. Before reaching the intended use, urea granules often undergo a long shelf life and intercontinental transportation. Therefore, urea should be unbreakable and non-clumping. To obtain strong granules, a derivative of formaldehyde, such as urea-formaldehyde resin, is often added to the urea melt.

Urine samples are susceptible to clumping due to storage under pressure, moisture migration, and high temperatures. To eliminate this phenomenon, coatings based on polyvinyl acetate and surface-active compounds, such as those described in US Patent 4,812,158, can be used. These coatings, however, have insufficient anti-caking activity after treating urea granules, especially in humid and warm conditions.

These anti-caking additives contain surface-active compounds that accelerate the formation of urea dust in humid conditions. Increased fines will increase urea flocculation and can cause serious dust problems during transport/processing. In addition, the presence of surface-active components can cause increased foaming when using urea in an aqueous medium, which is commonly used in the production of glue and urea-ammonium nitrate solutions.

Due to the fact that there are still problems in the production of urea granules, there is a need for a chemical product that can be used as an additive to urea to reduce the tendency of the granules to clump and form dust. This compound should be added in a small amount to the surface of the granules, be inexpensive, effective, non-foaming and safe for the environment.

Therefore, the subject of this invention is such a compound. The task of the invention is solved using the method according to the preamble, in which the additive contains a carboxylic acid compound of the general formula ХУ-(2)-СООН, in which 7 means a saturated or unsaturated hydrocarbon with 1-25 carbon atoms and X and M are selected from the group that consists of a hydrogen atom or a polar organic functional group, and in which the additive is introduced as an aqueous solution into urea granules, which are then dried.

Preferably, the polar organic functional group is selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group or an acetal group.

Of these polar functional groups, hydroxyl groups and carboxyl groups have been found to provide the best anti-caking characteristics. In addition, it was found that the formation of dust in treated urea granules was significantly reduced. In addition, it has been shown that carboxylic acid derivatives do not cause any pricing in the application of coated urea in the production of adhesives.

The best results with the compound of the invention are obtained when X is a hydrogen atom or a hydroxyl group and Y is a carboxyl group.

The carboxylic acid compound according to the present invention is applied to urea granules in a polar solvent, preferably water. The concentration of this compound in this solution should be 0.5-6Omas.9o, preferably 5-3Omas.bo. At this concentration, the compound is completely soluble and serves as a guarantee that the main recrystallization occurs on the surface of urea.

Sufficient coverage of urea granules with the compound according to the present invention can be obtained by using an amount of carboxylic acid compound equal to 100-10000 ppm, preferably 500-3000 ppm relative to the mass of urea granules.

The application of an aqueous solution to urea granules is carried out at a temperature of these granules from 30 to 90"C, preferably at 40-7070.

The invention also relates to a carboxylic acid compound intended for use in the method according to the present invention, while the compound differs in that it has the general formula ХУ-2-СООН, in which 7 means a saturated or unsaturated hydrocarbon with 1-25 carbon atoms and X and In selected from the group consisting of a hydrogen atom or a polar organic functional group.

To demonstrate the advantages of the method and compound according to the present invention, a number of experiments were conducted.

Additives were delivered by Bidta-Aiagisny. These compounds were dissolved in water with a concentration of 2095 (w/w), unless otherwise noted. The used urea granules are treated from the inside with urea-formaldehyde resin and delivered by Nuago Adi 5itsizki! V.M., the Netherlands.

Before coating, urea (1.0 kilograms per sample) was stored in sealed plastic containers in a thermostat at 50°C for 16 hours. Processing was carried out as follows. Urea is placed in a rotating coating drum, which has a temperature of approximately 50°C. Then, the fertilizer is sprayed with a coating in the amount of 0-5000 h/ml with further rotation of the drum for an additional 5 minutes. The processed fertilizer is transferred to a plastic vessel. After closing the vessel, the urea is allowed to cool below room temperature for 24 hours.

Example 1

To increase the coagulation of urea, the granules were given the opportunity to absorb up to 0.590% of water during their storage in a climatic chamber (temperature - 20"C, relative humidity - 8095). The tendency to lump, as well as the compressibility of urea granules, was evaluated by filling a transparent round tube with an inner diameter

Zsm with the help of 40 grams of "wet" urea. A plunger was inserted into the tube, with the help of which a pressure of approximately b0OkPa was applied to the sample. Immediately after the application of excessive pressure and again after 24 hours, the weight of the urea column was measured. From the data of two values (A height (95), the relative difference in height, which is a measure of compressibility, was calculated. The tendency to clumping of urea granules was determined by measuring the strength (M) of the collapse of a compacted sample formed in a transparent round tube. The results are the average values of at least five measurements.

The following supplements were tested as 2095 solutions in water at a dose of 1500mg per kilogram of urea.

Compressibility (A height (96)) 1 mixture disclosed in US Patent 4,812,158 was used as a formulation consisting of 6795 (w/w) water, 1195 (w/w) polyvinyl acetate and 2295 (w/w) alkyl sulfate; 2, the solution was heated to 502C before urea treatment;

C was used as a 1095 suspension at 802C in a dose of ZO0Och/million.

This experiment clearly shows that the tendency to agglomerate urea granules can be reduced up to 60905 by treating urea with a carboxylic acid compound substituted with a polar group. The mixture of US Patent 4,812,158 increased clumping. Similar results were obtained for the carboxylate-containing additive, namely, for

K-Mma tartrate. It turned out that the decrease in the tendency to clumping of urea granules is most evident when dicarboxylic acids are used. The compressibility of all processed urea is low compared to other types of urea. However, in all cases, treatment of urea granules with carboxylic acids reduces the compressibility of urea. Since the hardness of urea will increase, urea will be less prone to caking.

Example 2

The effect of additive dosage on urea granules was studied using a 2095 (wt/wt) solution of succinic acid in water. The solution was heated to 50°C before urea treatment.

Compressibility (A height (95))

Experiments show that the optimal dosage for the surface treatment of urea granules using the additive according to this new invention is from 500 to 3000 parts per million relative to the mass of urea.

Example C

The dust level in treated urea granules was investigated in the following manner. After coating the samples according to example 1 (1500 parts per million additive relative to the mass of urea), 250 grams of these treated urea granules were stored at 40"C for four weeks. Then 50 grams (accurately weighed) of urea were transferred to a 500 ml three-neck round-bottom flask. The flask was equipped with a glass column and a gas capillary connected to a cylinder of compressed air.The end of the gas capillary is placed in the urea.For 15 minutes, air is blown through the urea (2 bar overpressure), resulting in the formation of a fluidized system.

The remaining mass of urea was determined on analytical balances. Mass loss is an indicator of the amount of free dust. Urea was transferred back into a three-necked flask. Compressed air is blown through the urea for 1 minute, causing the formation of abrasive dust. The remaining urea was weighed on an analytical balance. The second mass loss is an indicator of abrasive dust. The determination was performed in duplicate.

Control (without additives). и /-/-:/ | /////r/Dr56777777 | 77777780 136

4-Aminobutyric acid /-:/ | 3477 | 77777765 11111199 1 mixture disclosed in US patent 4812158 was used as a preparation consisting of 6795 (w/w) water, 1195 (w/w) polyvinyl acetate and 2295 (w/w) alkyl sulfate; 2, the solution was heated to 507C before treatment with urea;

C was used as a 1095 suspension at 802C in a dose of ZO0Och/million.

It has been shown that dust formation can be largely suppressed by treating urea with compounds containing carboxylic acid.

Example 4

The foaming property of coated urea was studied by conducting a small experiment on the production of wood glue. For this purpose, 40 grams of urea were transferred into a 2-liter glass chemical beaker.

Urea was dissolved in a mixture of 50 ml of demineralized water and 45 ml of formaldehyde (3795). The mixture was stirred with a magnetic stirrer at a constant speed (3750 rpm) and heated to 90°C. When 907 was reached, 1 ml of glacial acetic acid was immediately added, while strong foaming occurred. The highest level of foam reached was noted on the beaker. The corresponding volume is pricing indicator: the lower the volume, the lower the pricing trend Results are averages of at least two measurements.

The following additives were tested in the form of 2095 solutions in water at a dose of 1500 parts per million relative to the weight of urea. (ml)

Polyvinyl Acetate: Alkyl Sulfate - 1 mixture disclosed in US Patent 4,812,158 was used as a formulation consisting of 6795 (w/w) water, 11905 (w/w) polyvinyl acetate and 2295 (w/w) alkyl sulfate.

A small study in the production of wood glue showed that the additives of this invention compared to the control product do not cause additional foaming when treated urea is used in an aqueous medium. This was expected because the compounds themselves do not have surface-active properties.

Example 5

To evaluate the performance characteristics of urea granule coatings containing carboxylic acid, formaldehyde-free urea granules were treated with selected additives. The urea was then allowed to absorb up to 0.295% of water by storage in a climate chamber. The tendency to agglomerate as well as the compressibility of the granules was investigated as described in Example 1.

The following supplements were tested in the form of 2095 solutions in water at a dose of 500Omg per kilogram of urea.

Compressibility (A height (90) Tendency to clumping (M)

Control (no additive)

Polyvinyl acetate: alkyl sulfate 5 12!

Яблучнакислота.й/-/-://1/Ї7777777711111112111111111111Ї11111111110911111 1 mixture disclosed in US patent 4812158 was used as a preparation consisting of 67905 (w/w) water, 1195 (w/w) polyvinyl acetate and 22905 (w/w) ./wt.) alkyl sulfate; 2, the solution was heated to 507C before processing the urea granules.

The test shows that lumping of urea granules can be significantly reduced by using the coating additives of the present invention.

Claims (12)

1. The method of obtaining urea granules with improved properties, especially the tendency to agglomeration, dust formation and foaming characteristics in an aqueous environment, by introducing a compound to the surface of urea granules, which is characterized by the fact that the compound is a carboxylic acid compound of the general formula ХУ-7-СООН, wherein 7 is a saturated or unsaturated hydrocarbon having 1-25 carbon atoms and X and Y are selected from the group consisting of a hydrogen atom or a polar functional group, wherein the polar functional group is selected from the group consisting of a carboxyl group, a hydroxyl group, amino group or acetal group, and the compound is introduced as a solution in a polar solvent to the surface of the urea granules, which are then dried. 2. The method according to claim 1, which differs in that the polar solvent is water. 3. The method according to claim 1 or 2, which differs in that 7; contains 2-5 carbon atoms. 4. The method according to claim 1, which differs in that X represents a hydrogen atom or a hydroxyl group, and Y represents a carboxyl group. 5. The method according to claim 1, which differs in that the aqueous solution has a concentration of a carboxylic acid compound equal to 0.5-60 wt. 90. 6. The method according to claim 5, which differs in that the specified concentration is equal to 5-30 wt. 90. 7. The method according to claim 6, which differs in that the concentration of the carboxylic acid compound relative to the mass of urea is 100-10,000 ppm, preferably 500-3,000 ppm. 8. The method according to item I, which differs in that during the addition of the aqueous solution, the temperature of urea is 30-90 "С, preferably 40-70 2С. 9. Use of a carboxylic acid compound of the formula ХУ-7-СООН, in which 7 is a saturated or unsaturated hydrocarbon with 1-25 carbon atoms and X and U are selected from the group consisting of a hydrogen atom or a polar functional group, where a polar functional group is selected from a group consisting of a carboxyl group, a hydroxyl group, an amino group or an acetal group, in the method according to any of the preceding items as an additive to urea. 10. Application according to claim 9, where 7. contains 2-5 carbon atoms. 11. Application according to claim 10, where X represents a hydrogen atom or a hydroxyl group, and Y represents a carboxyl group. 12. Application of a carboxylic acid compound of the formula ХУ-7-СООН, in which / means a saturated or unsaturated hydrocarbon with 1-25 carbon atoms and X and U are selected from the group consisting of a hydrogen atom or a polar functional group, where a polar functional group is selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group or an acetal group, and a solvent in the method according to any of the previous items as an additive to urea.