FI80010C - Coating agent for fertilizer in particulate form - Google Patents

Description

1 80010 Coating agent for particulate fertilizers

The invention relates to a process for providing particulate materials with a protective coating. More specifically, the invention relates to the coating of particulate fertilizers, such as ammonium nitrate, with an amine-siloxane reaction product.

Diatomaceous earth (DE) and treated clays have previously been used to coat and / or standardize particulate fertilizers such as ammonium nitrate. However, for several reasons, diatomaceous earth is becoming an increasingly unfavorable coating material for fertilizers. One reason is that the quality of the buttermilk itself has deteriorated because the better qualities have been removed by digging. Defective diatomaceous earth grades have resulted in coatings that do not meet the physical and chemical requirements that limit acceptable diatomaceous earth coatings. Storage and handling problems have arisen when using defective diatomaceous earth coatings.

Another problem associated with the use of diatomaceous earth and clays is the always present dust formation when handling diatomaceous earth because it is a relatively dry, small particle size solid. Usually about 1-1.5% by weight of diatomaceous earth is used to coat the ammonium nitrate particles. However, not all diatomaceous earth adheres to fertilizer particles. This fact leads to serious problems in ammonium nitrate production plants, causing e.g. the need for additional maintenance of the equipment, additional cleaning costs, etc. In addition, the customer suffers serious handling problems in the case of ammonium nitrate coated with diatomaceous earth.

Another problem with diatomaceous earth is that the price of a product for agricultural use has risen sharply in recent years as the quantities available have fallen as a result of the shift to other markets. As diatomaceous earth producers no longer need agriculture to consume their products, 2,80010 ammonium nitrate producers are in a vulnerable and costly position. Thus, there is a need to find a satisfactory substitute for diatomaceous earth for use as a fertilizer coating.

Different types of fertilizers have been coated with different materials to provide a more durable product. Urea is usually coated with kaolin clay or treated with formaldehyde to reduce caking. However, due to its small particle size, kaolin is dusty. On the other hand, urea formaldehyde treatment does not give a completely satisfactory product.

When phosphate-based fertilizers such as ammonium phosphate, superphosphate, homogeneous N-P-K fertilizers, etc. are dried to a very low water content to reduce the tendency to agglomerate, they become quite dusty during handling. Fuel oil is often used as a surface coating to reduce dust formation. Although fuel oil reduces dusting to some extent, it is not fully effective for this purpose, and this is not a good use for an energy-containing substance.

Organic materials have already been used as coatings for particulate fertilizers. Accordingly, U.S. Patent No. 4,259,102 discloses a heterocyclic polymer that can be used as a fertilizer coating. U.S. Patent No. 3,660,070 uses high molecular weight vinyl and acrylate type polymers as a coating. U.S. Patent 3,388,990 describes a very similar type of solution. U.S. Patent 3,544,297 discloses polyethylene, polyvinyl chloride and polyacrylonitrile as coating materials. U.S. Patent 3,475,154 describes fertilizer particles coated with a multilayer coating comprising thermoplastic and thermoplastic to provide a sparingly water-soluble fertilizer. None of the above references mention any of the ingredients used in the coating composition of this invention.

U.S. Patent 3,883,518 discloses a method of preparing a slow release fertilizer by providing a particulate fertilizer substrate with a multilayer coating having an outer layer of a hydrophobic material. That reference also mentions the use of a base layer which can be selected from a wide variety of organic compounds. U.S. Patent No. 3,223,518 also mentions that the main feature of a fertilizer product is water resistance, which is characterized by solids that remain within the shell-like, water-insoluble outer coatings. Any fertilizer product that does not have this property, including the product of the present invention, obviously does not fall within the scope of the reference. Furthermore, the product of the present invention is not a slow-release, multilayer coated product having a hydrophobic outer coating layer. Furthermore, the reference product has a large amount of coating material, i. about 7% by weight, while the amount of coating material of the present product is in most cases less than 0.1% by weight.

U.S. Patent No. 3,951,638 discloses a granulation process in which one step uses an organosilicon compound to control the accumulation of dust in the fertilizer particles. Therefore, the reference does not disclose the coating of fertilizer particles with organic material. Assuming that the dust is an inert material, the organic matter appears to act as a moisture barrier, a fact which is contrary to the present invention.

U.S. Patent 4,150,965 discloses the use of an alkylamine-mineral oil combination as a coating material in an ammonium nitrate fertilizer. The reference describes a three-step coating method, while the present method is usually a one-step coating method. In the method of the reference, a fertilizer containing ammonium nitrate is treated with an alkylamine at a relatively hot temperature, i. at a temperature at least 5 ° C higher than the melting point of the amine or amine-containing mixture. In fact, the reference mentions that the granules cannot be satisfactorily coated at 50 ° C, whereas the present invention provides excellent coatings on ammonium nitrate at less than 38 ° C. Yet another reference in the reference contradicts the present invention, since the reference states that only alkylamine must be added to the fertilizer in the first process step. This means that the amine cannot be premixed with another compound if acceptable results are to be obtained. In the present process, on the other hand, the amine is premixed with another substance, i. with silicone fluid, before applying to the fertilizer particles. Another difference between the reference and the present invention is that the reference does not mention that the coating method is effective for fertilizers which do not contain a diluent. Fertilizer-containing fertilizers containing a diluent are described in the characters of your embodiment. Thus, there remains a need to find a method for obtaining fertilizer particles with a better coating material, especially ammonium nitrate.

Thus, the present invention provides a protective coating for fertilizer particles that reduces dusting, minimizes clumping of fertilizer particles and breakage of granules, and makes handling of particulate fertilizer much easier.

Briefly, this and other objects of the invention, which will be described in more detail below, are achieved with a particulate substrate provided with a protective coating which is the reaction product between at least one amine and a siloxane. In a preferred embodiment of the invention, the particulate substrate is a granulated ammonium nitrate fertilizer.

A more complete understanding of the invention can be obtained and its advantages can be more clearly understood by examining the accompanying drawing, the illustration of which is a flow chart showing the mixing of the coating components according to the invention and the application of the coating material.

s 80010

Each material suitable for coating a particulate fertilizer must have several desired properties. The coating material must be compatible with the fertilizer, i.e. it must not damage the fertilizer or make it dangerous, which is very important in the case of ammonium nitrate. As unprotected personnel usually handle the fertilizer and apply it to the farmland, the coating must be non-toxic. In some cases, when a hygroscopic salt such as ammonium nitrate is coated, the fertilizer readily absorbs water from the surrounding air. This results in agglomeration and breakage of the granulated fertilizer. Thus, an acceptable coating material must be virtually retention-free or eliminate water absorption from the particulate hygroscopic fertilizer. Another important feature of the coating is that the coating covering the particles must be sufficiently uniform so that the particles do not come into contact with each other at points in the uncoated areas. If this type of contact is not prevented during storage of ammonium nitrate, agglomeration of the fertilizer particles will follow, as the particles will adhere to each other at areas where insufficient coating allows contact between the particle surfaces. The raw materials for the coating material must be abundantly available so that the volume does not impede the production of the coated fertilizer product. The coating material must be firmly attached to the fertilizer particles from the time of treatment until the coated fertilizer is applied to the field.

Other advantageous, but not essential, properties that the coating material should have are that the price of the ingredients per tonne of fertilizer should be reasonable and that it should be easy to handle from a production point of view. However, for both of these factors, some cost and inconvenience can be allowed if a very well coated fertilizer product is obtained.

The coating material of the present invention has been found to meet all of the above requirements. The present coating material is the reaction product of an amine and a polymeric siloxane.

The amine component of this coating composition is a material that is semi-solid or solid at room temperature. The melting point of the amine should be between about 43 ° C and about 93 ° C and should not decompose at these temperatures. Suitable amines include e.g. primary, secondary and tertiary, straight-chain or branched amines containing from 12 to 18 carbon atoms and amines containing cyclic hydrocarbon radicals. Saturated cyclic amines and saturated polyamines can also be used as long as they have the physical properties described above. Amine mixtures can also be used, and in fact industrially produced long-chain fatty amines are often mixtures of amine compounds and are very well suited for use in this invention. Amines containing unsaturated hydrocarbon radicals and aromatic hydrocarbon radicals should be avoided when coating ammonium nitrate-type substances, as there is a risk of the formation of dangerous compounds. This factor is less important when coating less hazardous substances. The preferred amine mixture contains amines having the formula: ch3- (ch2-ch2) x-ch2-nh2 where x is 6, 7 or 8. The properties of this particular mixture are as follows: a) Solid at 24 ° C

b) Melting point (° C): 49-54 ° C

c) Freezing point (° C): 43 C

(d) Specific gravity (150/60), g / cm3: 0,794 (e) Viscosity (66 ° C) cP: 3 (f) Colorless (g) Purity 97% 7 80010 The siloxane reagent used as the second component of the coating material should be slightly viscous at ambient temperature or if molecular weight is high, it should melt in the same range as the amine. Alternatively, the solid siloxane should be such that it melts and mixes homogeneously with the amine reagent at a temperature in the range of about 43 ° C to about 93 ° C. Suitable siloxanes include those having lower alkyl, lower alkoxy and lower alkyl amino substitutions. The siloxane is preferably substituted with an amine, but may be substituted with a polyamine. The siloxane should not be a hydroxysiloxane. However, siloxanes having a cyclic structure are also suitable siloxanes. The preferred siloxane is an amino-substituted polydimethylsiloxane having the formula: CH., “CH0 CH-; 3 I 3 I 3 NHo-Si-0 - Si-0 - Si-NH_ 2 II ί 2 CH3 ch3 x CH3 where x is such that the siloxane has the following properties: a) Liquid at 24 ° C b) Specific gravity (75 / 75), g / cm 2: 0.985 c) Viscosity (24 ° C) cP: 53 d) Colorless e) Purity 100%

The most important property of the amine-siloxane mixture is that it should be a homogeneous mixture with a viscosity of less than 10 cP at the temperature of the production conditions.

The amine-siloxane coating can be applied to the fertilizer particles using any industrially acceptable method of providing a uniform and acceptable coating of the coating material to the fertilizer particles. Both the β 80010 batch process and the continuous process can be used to mix the ingredients of this invention. Since the amine used is usually solid at ambient temperatures, it is usually heated sufficiently for liquefaction. A temperature between 54-93 ° C is usually sufficient to liquefy the amine. The amine is then mixed with the siloxane in the desired amount until a homogeneous mixture is obtained. Mixing can be performed in a simple mixing tank, a static mixer connected in parallel, or the like, sufficient to provide a homogeneous mixture of the two ingredients. The materials of the mixing equipment and the production equipment must, of course, be such that they do not corrode under the influence of the reagent. The mixture should be made in an amount sufficient to cover a certain amount of fertilizer particles with a layer of a certain thickness.

The ratio of the amounts of amine to siloxane can vary within wide limits, but the essential requirement is that the ratio gives a coating material having the properties listed above. The quantitative ratio of the two reagents is wide so that the acceptable amine: siloxane ratio is between 5:95 and 95: 5. These ratio limits can be exceeded on either side, but this advantage does not achieve any benefits. The preferred amine: siloxane ratio is between 70:30 and 90:10.

The prepared coating composition can be used immediately or can be stored for later use. The nature of the coating composition is such that protective clothing should be worn by personnel handling it. Preferably, however, the coating composition is stored in molten form for only a few days because at elevated temperatures (above ambient temperature) the polymerization increases. If the coating mixture is to be stored for longer than a few days, the mixture should be solidified by cooling and then remelted before use. Storage is preferably performed under an inert gas atmosphere, such as under nitrogen.

9 80010

The coating composition or amine reagent of the invention should not come into contact with the hot ammonium nitrate melt.

Because the amine is an organic substance, contact between the amine and hot ammonium nitrate can create a hazardous situation. Therefore, any spilled and waste ammonium nitrate with a coating should be disposed of properly and not recycled to the ammonium nitrate plant. In the case of fertilizers which are not in this way dangerous, such precautions need not be taken into account to such an extent or at all.

Precautions should also be taken when handling siloxane and amine reagents before combining them in the form of a coating composition. High temperatures and exposure to air and humidity promote the polymerization of the siloxane. Therefore, the siloxane reagent should be stored under an inert atmosphere at a temperature not above 43 ° C. Caution should be exercised when handling hot amine fluid and therefore protective clothing is recommended. Prolonged skin contact with amine may result in dermatitis. The amine may decompose slowly if heated to a temperature well above 93 ° C, and therefore the amine should be stored at this temperature at most. Because amines are capable of absorbing carbon dioxide from the atmosphere, the amine should also be stored in an inert atmosphere.

The chemical properties of siloxane are such that it is sensitive to moisture and oxygen so that it hardens when exposed to these. Therefore, siloxane should be stored under an inert gas atmosphere. In fact, the mixture of amine and siloxane should be treated under an inert gas atmosphere when the mixture is applied to the particulate substrate to be coated.

The mixed and ready-to-use coating mixture is in liquid form. The mixture can be applied to the particulate fertilizer by any acceptable and practical method in which the liquid is applied to the particulate solid substrate in large commercial production volumes. Usually, the heated mixture is applied, e.g., by spraying, film rolling, or spraying the liquid mixture onto a circulating drum into which the fertilizer particles fall, etc. The temperature of the coating mixture must be kept high enough to remain liquid during application to the fertilizer particles. A temperature in the range of about 54 to about 93 ° C, preferably 65 to 82 ° C, is sufficient to keep the mixture molten. Unlike other coating processes, the present method does not require heating of the fertilizer particles. In the case of ammonium nitrate fertilizer, the product is a particulate product at an elevated temperature. From a production point of view, the particulate ammonium nitrate product can be practically coated at a temperature in the range of 31-32 ° C. The nature of the coating composition is such that it can be easily applied to an ammonium nitrate fertilizer at a temperature in the range of 16-110 ° C.

Whatever method is used to coat the fertilizer particles, the only relatively critical factor in the contact time between the liquid coating agent and the particles is that the contact should be long enough to achieve a uniform coating. When using the roll coating method, the particles should rotate forward only as far as necessary to achieve a uniform coating.

If the coating is applied to cold particles, no cooling is required afterwards. In the case of ammonium nitrate, forced heat transfer cooling may be used in the coating apparatus, but this is not necessary. However, cooling the particles contributes to the solidification of the coating to be applied. The coating material solidifies as heat is removed from the coating with the aid of a relatively colder fertilizer substrate below after the fertilizer particles have cooled to the preferred temperature range. If the coated particles are cooled using heat transfer, care must be taken not to cool the particles 11 8001 0 too quickly, as this will not allow the coating material sufficient time to cover the particles uniformly.

The coating conditions used are such that the amount of coating applied is sufficient to provide a sufficient protective coating. Usually 0.005 to 0.20% by weight is sufficient to obtain good results, and an even more preferred amount is 0.01 to 0.05% by weight. If the coating is less than 0.005% by weight, it may not be sufficient to give the particles a uniform coating with the essential properties described above. If a coating material is used in excess of 0.20% by weight, the cost increases, but no additional benefits are achieved.

The figure shows a flow chart of an embodiment of a method by which the present amine-siloxane coating can be applied to a particulate substrate. Tanks 1 and 3 are tanks for the siloxane reagent and the amine reagent of the coating mixture, respectively. Each reagent is pumped from its own tank in an inert gas atmosphere by pumps 5 and 7 along pipes 9 and 11 to the mixing tank 13.

Once the ingredients have been mixed together, the mixture is pumped by a pump 15 along a pipe 17 to the coating material storage tank 19. The tanks 1, 3 and 13 are provided with pipes 2, 4 and 6, respectively, for recycling the liquid component contained in the tank, if such recycling is desired. The ammonium nitrate granules are passed along a pipe 21 to the coating drum 23. At the same time, the coating material is taken from the tank 19 via the pump 25 and sprayed onto the coating drum 23 via the pipe 27 so that the fertilizer granules are coated. Coated ammonium nitrate granules are removed from the drum.

12 80010

After the foregoing general description, the invention has been illustrated, but not limited, unless otherwise indicated, by way of example.

Example I

The ammonium nitrate granules were sprayed with a mixture of 70 parts by weight of the mixture of long-chain fatty amines described above and 30 parts by weight of the amino-substituted polydimethylsiloxane described above until the granules had a coating mixture of 0.03% by weight. The temperature of the coating when applied to the granules was 82 ° C. The temperature of the granules at the time of coating was 31 ° C. The coating of the granules took only 15 minutes.

Using a previously known method, ammonium nitrate granules were coated with diatomaceous earth. The coated granules were then subjected to the experiments listed in Table I and the results obtained are also shown in that table.

The coated granules were subjected to the following experiments: A. 24 Hour Ball-Screen Hardness Test A 100 g sample of granules ranging in size from -8 to +10 mesh was placed on a 12 mesh screen. Then, 120 steel balls with a diameter of 1 mm were placed on the sieve, and the sieve with particles and spheres was shaken in a Ro-Tap for 15 minutes. The amount of -12 mesh material generated was measured. The percentage of grain that remained unbreakable is a measure of hardness. This test measures the impact resistance of the granules to impact. The higher the index, the stronger the balls.

B. Single Granule Hardness Test From a sample of -8 to +10 mesh coated granules, 10 granules were randomly selected. A compressive force was applied to each granule until it broke. The average force required to break the granules was recorded in kg / cm. This test measures the resistance of a grain to a continuously acting compressive force.

13 80010 C. Deformation test Granules coated on a 75 ml sample were subjected to a continuous measuring pressure of 3850 kPa in a metal cylinder for 5 minutes. The volume was measured before and after compression so that the deformation value as a percentage was calculated. The degree of agglomeration was determined subjectively based on how difficult it was to remove the sample from the cylinder. The scale was as follows: (1) not at all, (2) very low, (3) low, (4) moderate, (5) hard, and (6) very hard. This experiment measures the tendency of fertilizer granules to agglomerate due to plastic deformation and / or capillary adhesion.

D. 24 Hour Caking Test 300 g of coated fertilizer granules were subjected to a special pressure of about 315 kPa in a specially designed cylinder for 24 hours. The degree of agglomeration was determined by gradually increasing the pressure on the cylinder after removing the threaded plug from the bottom. The pressure required to squeeze the material through this opening was taken as the caking index. This test measures the tendency of a fertilizer sample to agglomerate after applying a plastic deformation and capillary effect to the sample.

E. Abrasion Test 400 g of coated granules ranging in size from -8 to +10 mesh were passed through a laboratory screw conveyor (diameter 5.7 cm, length 81 ora) six times at a speed of 40 l / min. After the last pass, dry air was blown through the device to remove all small particles and dust. The entire sample was then placed on a 14 mesh screen and the screen was shaken with the sample material in a Ro-Tap shaker for 14 minutes. Material less than 14 mesh was weighed and calculated as a percentage. The value thus obtained was the abrasion value. This test measures the friability of the granules and the tendency to break due to abrasion.

14 80010 F. Accelerated caking test 285 ml of coated ammonium nitrate product was placed in a cylinder designed to expose the sample to ambient conditions. The product was pressed to a measuring pressure of 28 kPa and kept at a temperature of 32 ° C and a relative humidity of 60% on the wet side and 25% on the dry side. Wet cycles lasted 24 hours and were followed by dry cycles lasting 12 hours, except for the last dry cycle, which lasted 24 hours. The agglomerated fertilizer was removed from the cylinder, placed in a compression tester, and the pressure was gradually increased until the cake broke. The pressure was recorded at this point. The experiment was repeated four times and the samples were compared to samples made of the control material (they were usually diatomaceous earth-coated ammonium nitrate granules). The clumping number was calculated as the ratio obtained by comparing the average fracture pressure of the sample of interest with the average of the corresponding control samples, or as a percentage of the reference fracture toughness. This experiment measures the tendency of a fertilizer to agglomerate as a result of crosslinking or coalescence of granular crystals due to moisture absorption, moisture migration, and salt recrystallization at moderate pressure.

G. TF.I. Combustion Test 72.6 kg of ammonium nitrate product was mixed with a 36 kg bag of kraft paper cut into approximately 5 cm squares. The mixture was placed on a platform pellet in a combustion chamber with an inside diameter of 40 cm and described in The Fertilizer Institute’s official ammonium nitrate classification guidelines.

4.5 kg of soft pine chips, pieces measuring 1.3 x 5.1 x 20 cm and stacked airily under the grate, were ignited with a standard railroad fuse in the middle under a pile of wood. When the heat was so great that molten ammonium nitrate began to drip into the flames, the fire door was closed and the combustion chamber was covered and earth was collected around the fire door. In this way, ammonium nitrate remained the only source of oxygen. This test determines how ammonium nitrate should be classified for packaging, transport and storage. A product with a burning time of one hour or less cannot be classified as an "ammonium nitrate fertilizer" and is subject to strict transport regulations.

The results obtained in these experiments for the coated ammonium nitrate granules described above are shown in Table I.

Table I

Experiment with "Similene" Diatomaceous coated coated _ granules_ granules 24 hour ball screen hardness,% 74 100 2

Hardness of one grain, kg / cm 30 40

Deformation: - Deformation% 13.2 11.0 - Degree of caking very low hard 24 hour caking, kPa O 350

Abrasion,% 1.6 19.3

Accelerated caking, kg 10.4 479 T.F.I. combustion test, min 77 151

Example II

Two of the experiments, namely the T.F.I. combustion test and the 24-hour ball-screen hardness test, are very important. The combustion test is the most important of the two. The test requires that the ammonium nitrate fertilizer sample not burn in less than 60 minutes. If the burning time is more than 60 minutes, the ammonium nitrate sample may be classified as a fertilizer for transport. It can be transported in bulk or packed in bags as used in the fertilizer industry. If the burning time is less than 60 minutes, special packaging and handling measures must be followed, all of which increase the price of the fertilizer and are therefore not acceptable.

In previous experiments, ammonium nitrate granules coated with the amine-80010 mineral oil combination described in U.S. Patent No. 4,150,965 were subjected to some screening experiments, but although good results were obtained in some experiments, nothing passed the combustion test or ball screen.

Table II below lists the coating material tests and test results for the various coated ammonium nitrate granules. The experimental results show that only two coated samples passed the T.F.I. combustion test, which were a sample coated with a siloxane-amine coating and a sample coated with siloxane alone. But granules coated with siloxane alone proved to be very poor in the ball-screen hardness test. In addition, particles coated with siloxane material alone remained tacky for several hours after coating, i. until the slow polymerization reaction was complete. Such a coated product is not acceptable and can cause clumping problems when packed in bags, filling carts, etc. immediately after coating.

Of all the coated particles examined, only the ammonium nitrate particles coated with the amine-siloxane mixture gave good results in all experiments. This result was completely surprising and unpredictable.

Another advantage of the coating material of this invention is that a satisfactory coating can be obtained by applying a single application to a particulate substrate, while other coatings, such as a mineral oil-amine combination, had to be applied several times to provide a uniform coating.

Furthermore, the coating composition of this invention has the advantage that it can be applied to chilled fertilizer granules, while the amine coating alone or the amine and the subsequent second coating material must be applied to the hot granules. This complicates the coating process because the amine is applied at 17,800 10 before the granules are cooled. Thus, it is very difficult to separate the coating system from the ammonium nitrate synthesis system.

Another aspect of the process described in U.S. Patent No. 4,150,965 is that a coating drum specifically designed for this purpose is required to achieve uniform application of the amine. The flow properties of the amine-siloxane coating of this invention are quite different from those of the amine alone and thus no unusual coating drum is required.

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Example III

Table III below shows the effect of the coating according to Example I and coatings containing different amounts of the amine and siloxane components on the fertilizer granules. 0.01% by weight, expressed as the minimum preferred amount of coating, is preferred for the practical handling of the coating composition, and not based on the actual behavior of the coating. When the amount of coating is less than the preferred lower limit, it is already difficult to guarantee the uniformity of the coating. An upper limit of 0.15% by weight is preferred because the cost of the amount of coating material increases faster than the benefits achieved with a larger amount of coating and because the coated granules remain moist and sticky for some time after coating.

An upper limit of 95: 5 for the amine: siloxane ratio is preferred because this amount of siloxane is sufficient to guarantee an acceptable T.F.I. The amine coating alone does not always pass the combustion test. The lower limit of the amine: siloxane ratio of 60:40 is mainly based on material cost and behavior in the accelerated caking test, as shown in Table III.

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Example IV Pilot plant results

Approximately 1,000 tons of ammonium nitrate coated with the amine-siloxane coating of Example I was tested in field storage experiments. Fertilizer granules with 0.03 and 0.06% by weight of coating material were studied. A 100 ton batch of ammonium nitrate was stored in bulk in an unventilated magazine at an average of 27 ° C for about 7 weeks at high humidity. The stored granules were in excellent condition after this period. On the other hand, it is known that diatomaceous earth-coated ammonium nitrate particles rapidly begin to deteriorate in quality after being stored for three weeks in such an environment.

Some of the test material was transferred by pneumatic bulk trucks to the MCC dealer. The material was easy to disassemble, and there was no characteristic heavy dusting of diatomaceous earth-coated ammonium nitrate particles.

Some of the coated test material was transported in 100 ton bulk hopper wagons. The wagons were in transit for about 2 weeks, during which time they were exposed to hot air and full sunshine most of the time. There were no problems unloading the wagons at the destination station. When diatomaceous earth-coated ammonium nitrate granules are transported under these conditions, hard lumps form and clumping occurs in the walls of the wagon.

Example V

Table IV below shows the results obtained by coating the granular N-P-K fertilizer with the coating material of Example I.

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Table IV

Sample Amount of dust evolved, ppm_

Uncoated N-P-K fertilizer 53 0.25% by weight oil-coated N-P-K fertilizer 4 0.05% by weight amine siloxane coated N-P-K 12 0.25% by weight amine siloxane coated N-P-K 19

The results shown in the table show that the coating material of the present invention effectively forms a dust suppressing coating.

Example VI

Table V below shows the results obtained by coating formaldehyde-impregnated particulate urea with the amino-siloxane coating material according to the invention and compares the results obtained with uncoated, formaldehyde-impregnated urea particles: .

Table V

Sample 24-hour tank Deformation test _ wear test% / ° _ Uncoated urea 2 15.4 / low

Amine-siloxane coated - 0 16.5 / low urea * 3% clay coated urea 55 15.4 / hard * amine: siloxane ratio 90/10, coating amount 0.02%

The caking results obtained with the particles coated with the amine-siloxane reagent are surprisingly good, especially when compared to clay-coated urea.

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Stability studies on coated ammonium nitrate granules_ A. Amine-siloxane coated ammonium nitrate combustion test results _______

Eight samples of finely divided ammonium nitrate coated with the amine-siloxane coating of Example I were subjected to the combustion test described in Section 4.0, "Definition and Test Procedures for Ammonium Nitrate Fertilizer", published by the Fertilizer Institute, January 16, 1973. Samples 1- 3 had a coating of 0.06% by weight, while samples 4-8 had a coating of 0.03% by weight. The results obtained are shown in Table VI.

Table VI

Sample No. Burning time Residue weight 1 1 h 40 min 3.29 kg

2 59 min O

3 54 min 0 4 2 h 23 min 0 5 1 h 27 min 0 6 58 min 0 7 2 h 40 min 19.75 kg 8 1 h 13 min 0 B. Storage of coated ammonium nitrate granules in bulk_

Four piles of 100 tons of ammonium nitrate particles were stored, which particles were coated with the coating material of Example I. One heap (0.06 wt%) was stored for 11 weeks, while the remaining three heaps (one heap was coated with 0.06 wt% and the remaining two were 0.03%) were stored for 5 weeks. The latter three piles were in excellent condition after 5 weeks. The pile with 0.06% by weight of coating in the granules had a soft surface layer with a depth of 1-2 grains with dry, swollen granules. The ammonium nitrate under the shell was slightly hardened, but it detached as 24,8001 0 whole grains using a small force. Each 0.03% by weight pile had a soft shell with a thickness of 0.6 cm or less and consisted of slightly sugared and swollen granules. There was little hardening under the shell. There were small differences in the storage properties of the heaps. All 5-week piles were dry despite humid storage conditions and standing in the water on the floor of the magazine.

The 11-week-old pile had a soft surface layer 1.7-2.5 cm thick. This layer may have consisted of ammonium nitrate and diatomaceous earth spilled over the belt conveyor above. Below the shell, the ammonium nitrate had hardened only slightly. The loader of the magazine took the bucket from the pile and transferred the ammonium nitrate to the loader. The loader had broken the pile so that most of the ammonium nitrate in the bucket was in a free-flowing form. The remaining soft cakes did not pose a problem in the loader. When the coated ammonium nitrate of the invention was loaded onto a waiting delivery truck, dusting was very low. The loader cut the 11-week-old pile containing 0.06% by weight in half. The part that had moved aside disintegrated into dry, free-flowing granules. The material in the center of the pile was in as good condition as the one at the edges and no significant amount of fines was detectable.

Large lumps began to form in a pile of diatomaceous earth-coated granules that had been stored in the magazine for 2 weeks. The surface of ammonium nitrate felt moist to the touch, so its quality was inferior to that of the product of this invention. Samples coated in accordance with this invention were characterized by a small amount of moisture and fines. One sample contained 5.9% fines, but it was taken with a peak that could cause crumbling. The sample taken from the middle of the heap contained about 3.4% fines. Instead, in a 25 8001 0 diatomaceous earth-lined pile in the same warehouse, the fines were concentrated in the center of the pile. It is not uncommon for a pile containing diatomaceous earth coated with diatomaceous earth to contain 10-15% fines in the middle.

The product coated according to the present invention had a hardness value of 17-28 kg / cm for one of the 2 granules. These values did not decrease significantly during storage. The hardness of one grain of the diatomaceous coated sample was 23 kg / cm, which must be considered a small value compared to previous experience. Each sample had a low ball-screen hardness value (75 balls), except for a sample taken from the center of a pile of amine-siloxane-coated particles.

Samples listed in Table VII; 1. 0.06% product, prepared 7/20/82; the sample was taken at a height of 7.6 cm above the ground.

2. 0.06% product, prepared 6/17/82; the sample was taken at a height of 7,6 cm above the ground with a spike-like sampling device.

3. Sample similar to No. 2; a clump taken from the pile.

4. Sample similar to No. 2; a sample taken from the center of the pile after the loader had passed through the pile.

5. 0.03% product, prepared 7/20/82; the sample was taken from a height of 7.6 cm above the floor surface.

6. 0.03% product, prepared 7/20/82; the sample was taken from a height of 7.6 cm above the floor surface.

7. Diatomaceous earth coated pile; the sample was taken at a depth of 3.8 cm from the surface.

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Table VII

Sample Storage-% H «0% fine- Single-grained- Rub- Rub- 4½. time split test test hardness _ hardness% fines (kg / cm 2) (75 split _ _ _ _ ___balls) substance 1 5 weeks 0.19 2.0 23.7 2 2 11 weeks 0.20 5.9 * 22.5 2 3 11 weeks 0.11 2.9 25.7 0 4 11 weeks 0.17 3.4 27.6 67 4.0 5 5 weeks 0.17 1.2 17.3 0 4.3 6 5 weeks 0.17 1.6 24.4 2 4.5 7 2 weeks 0.19 3.2 22.9 1 * Sample taken with a spike-like device.

C. Other results obtained in the storage of coated ammonium nitrate_ (1) The top layer of sacks containing ammonium nitrate granules coated with 0,03% by weight of the amine-siloxane mixture of Example I and stored since 1 June 1982 was removed at the top. from a pile on a pallet. The sacks contained 0.6-1.3 cm of fully sugared ammonium nitrate located on the outer surface. These granules had been subjected to heat circulation near the roof of the magazine. Beneath the saccharified area were sacs of whole, free-flowing granules of ammonium nitrate. No granule breakage was observed in the other sack layers on the top pallet. The other sacks in the top pallet layers had some curing that came off during processing and had a small number of very small lumps, as shown in Table VIII below.

The number of lumps increased on the middle platform. These lumps were very soft and broke during handling. The most agglomeration was observed in the bedrock. The lumps were very soft on the bottom stage until the 9th floor (second to last) was reached. Clumps between soft and moderate were observed in the lumps of this layer.

27 8 0 0 1 0 Table VITI

Pallet / Layer Sacks of Sacks- Sacks% Fine Amount% Hardness Test Sample _ Weather_ _ _ _

High / 1. 2 - - 1.2

High / 3. 2 1.8 Very soft 0.8

High / 5. 2 1.0 Very soft 1.1

The middle / 3. 2 7.5 Very soft 0.8

The middle / 7. 2 18.5 Very soft 0.7

Ground / 2. 2 44.3 Very soft 1.0

Bottom / 5. 3 18.7 Very soft

Bottom / 9. 4 36.8 (2/3 moderate, - 1/3 soft)

Pallet / layer One ball ^ Ball screen hardness _ Hardness (kg / cin) (75 balls) _

High / 3. 22.4 O

The middle / 3. 19.5 7

Ground / 2. 26.6 O

2) The top sack layer containing ammonium nitrate granules coated with the amine siloxane coating composition of Example I (0.06% by weight) and stored since 17 June 1982 contained 4-5 cm thick powdered and softly agglomerated ammonium nitrate on the outer surface. Only the top 1.3 cm was powdery, the rest was agglomerated. Beneath the clumped part were the granules intact and free-flowing. Granule rupture was observed only on the first floor of the top stage. The remaining sacks of the upper platform had a large amount of clumping throughout. The hardness of agglomeration ranged from soft to moderate, as shown in Table IX below.

The amount of agglomeration remained high through the middle and lower platform, being 36-74% by weight. The hardness of the lumps was moderate.

These sacks should have been dropped several times to break the lumps.

28 8001 0 This material was prepared during the second hour of the factory test on June 17 and there was a considerable amount of diatomaceous earth on the granules. When the sacks were cut open, a faint odor of ammonia was also observed. These factors could adversely affect storage.

Table IX

Pallet / Layer Sample- Clump- Clump Finishing sacks% hardness of its substance _ amount _ _ amount% _

High / 1. 2 50.3 Soft 1.4

High / 3. 2 68.3 (2/3) of 1.0 laws; (1/3) soft

High / 5. 2 52.7 (2/3) of the Act; (1/3) soft

The middle / 3. 2 43.7 Moderate

The middle / 7. 2 66.4 Moderate

Low / 2. 2 52.5 Moderate

Low / 5. 2 73.9 Moderate

Low / 9. 2 36.4 Moderate

Note: This ammonium nitrate was prepared during the 2nd hour of the factory experiment. There was pretty much diatomaceous earth in the material, which could adversely affect the material.

Pallet / Floor Single granule? Ball screen hardness _ hardness (kg / cnP) (75 balls) _

High / 3. 28.2 1

The middle / 3. 21.7 2 (3) The top layer of the top pallet, containing ammonium nitrate granules coated with 1,5% by weight of diatomaceous earth and stored since 31 May 1982, contained 5 cm of moderately agglomerated granules on the outer surface. The granules below the pelleted part were free-flowing. No clumping was observed in the first layer sacks. The remaining sacks of the top platform had a small number of soft lumps. The amount of agglomeration was higher than that of the ammonium nitrate granules in the bag, respectively, coated with 0.03% amine siloxane, as shown in Table X below.

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The amount of agglomeration increased slightly in the middle platform, as no soft agglomerates were present at all. These bags would not have caused any problems for the consumer.

The highest amount of agglomeration was observed in the lower stage, the amount being 42-66% by weight. The hardness of the lumps was moderate throughout the lower platform. The sacks should have been dropped on the floor several times to break the lumps.

In judging these results, it must be borne in mind that the product was manufactured on a very cool day and therefore represents the "best possible" situation.

Table X

Pallet / Layer Sample- Clump- Clump Finishing sacks% hardness of its substance _ amount _ _ amount,%

High / 1. 2 35.3 Moderate 0.8

High / 3. 2 2.6 Soft 1.0

High / 5. 1 11.9 Soft

The middle / 3. 2 14.8 Soft 0.7

The middle / 7. 2 24.7 Soft

Low / 2. 2 42.3 Moderate

Low / 5. 2 65.7 Moderate

Low / 9. 2 51.8 Moderate

Pallet / Layer Single grain „Ball sieve _ hardness (kg / cin) hardness (7 5 balls)

High / 3. 19.9 73

The middle / 3. 25.6 36

Low / 2. 22.8 68 The present invention has been fully described above, but it will be apparent to one of ordinary skill in the art that various changes and modifications may be made without departing from the scope or spirit of the invention.

Claims (21)

30 8 0 0 1 0 A particulate fertilizer provided with a protective coating, characterized in that the fertilizer particles are coated with at least one amine compound which is a primary, secondary or tertiary amine of a straight or branched hydrocarbon or an amine containing a ring hydrocarbon group, and an alkylated siloxane, with lower alkoxy, lower alkylamino and / or amino, reaction product. Fertilizer according to claim 1, characterized in that said amine is a single compound or amine mixture which melts in the temperature range 43-93 ° C. Fertilizer according to claim 2, characterized in that said amine is a single compound or amine mixture, which amines are primary, secondary or tertiary, straight-chain or branched and have 12 to 18 carbon atoms. Fertilizer according to claim 3, characterized in that said amine is a mixture of compounds of the following formula: CH - (CH-CH) -CH -NH 3 2 2 x 2 2 wherein x is 6, 7 or 8. Fertilizer according to claim 1, characterized in that said siloxane is slightly viscous at ambient temperatures. Fertilizer according to claim 5, characterized in that said siloxane is substituted by an amino and contains lower alkyl and / or lower alkoxy substituents. 31 80010 Fertilizer according to claim 6, characterized in that said siloxane has the formula CH CH 1 CH 1 3 13 13 NH -Si-O-Si-O -Si-NH 2 1 | 12 CH CH x CH 3 L 3 J 3 wherein x is such that the viscosity of said siloxane is 53 cP at ambient temperature. Fertilizer according to claim 1, characterized in that the weight ratio of amine: siloxane in said coating is in the range from 5:95 to 95: 5. Fertilizer according to claim 8, characterized in that said range is from 70:30 to 90:10. Fertilizer according to claim 1, characterized in that the coating is present in said fertilizer particles from 0.005 to 0.20% by weight. Fertilizer according to claim 9, characterized in that the amount of said coating is 0.01 to 0.05% by weight. Fertilizer according to claim 1, characterized in that said fertilizer particles are ammonium nitrate granules. A process for providing a protective coating for fertilizer particles, characterized in that at least one amine compound which is a primary, secondary or tertiary amine of a straight or branched hydrocarbon group or an amine containing a ring hydrocarbon group and a siloxane substituted by lower alkyl is lower, with lower alkylamino and / or amino, a liquid reaction product in contact with the fertilizer particles at about 16 ° C to 110 ° C for a time sufficient to provide a uniform coating on the fertilizer particles. A method according to claim 13, characterized in that said mixture is applied to the fertilizer particles at a temperature between 54 and 93 ° C. A method according to claim 13, characterized in that the amount of the mixture applied to said fertilizer particles is 0.005 to 0.2% by weight. A method according to claim 13, characterized in that said fertilizer particles are ammonium nitrate granules. Process according to claim 13, characterized in that the amine: siloxane ratio in said coating is in the range from 5:95 to 95: 5. A method according to claim 13, characterized in that the viscosity of said coating composition is less than about 10 cP at an operating temperature. Process according to claim 13, characterized in that said amine is a single compound or amine mixture, which amines are primary, secondary or tertiary, straight-chain or branched and contain from 12 to 18 carbon atoms. Process according to claim 13, characterized in that said siloxane is substituted by an amino and contains lower alkyl or lower alkoxy substituents and is slightly viscous at ambient temperatures. 33 8001 0