IE841270L - Coating agent for nitrate and other materials - Google Patents

Description

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PATENTS ACT, 1964.

I COMPLETE SPECIFICATION "COATING AGENT FOR AMMONIUM NITRATE AND OTHER MATERIALS." aPfUCAn S---*5 , 1<— ;'?N ' •»., .*.1 '* MISSISSIPPI CHEMICAL CORPORATION, of Yazoo City, Mississippi 39194, United States of America, 4 y-- ir •' t i , - -J , f -- ^ A"" -' Another disadvantage of using ?iiatomaceous earth and clays is that there is always the undesirable problem of dust 5 generation in the handling of diatomaceous earth since it is a relatively dry, small particle size solid. Usually, from about 1-1.5% by weight of DE is coated on ammonium nitrate particles. Not all of the DE, however, adheres to the fertilizer particles. This fact results in serious problems for ammonium nitrate manufacturing plants which are the likes of additional equipment maintenance, extra clean-up costs and the like. Moreover, there are serious customer handling problems involved with DE ( coated ammonium nitrate.

Yet another problem with diatomaceous earth is that 20 the costs of agricultural grade diatomaceous earth have sharply increased oyer the past few years as the available supplies have decreased as a result of the diversion of supplies to other markets. Because diatomaceous earth suppliers no longer need the agricultural market as a consumer of their product, ammonium nitrate producers are placed in an increasingly more vulnerable and expensive i position. A need, therefore, exists for a satisfactory replacement for diatomaceous earth as a fertilizer ( coating agent.

Various types of fertilizers have been coated with ^ different materials in the past to produce a product of improved stability. Urea is usually coated with kaolin clay or is treated with formaldehyde to alleviate c ( caking. However, kaolin, because of its very small particle size, is dusty. On the other hand, formaldehyde treatment of urea does not yield a completely satisfactory product.

Phosphate based fertilizers such as ammonium phos phate, superphosphate, homogeneous N-P-K fertilizers and the like, which when dried to very low water contents to reduce their caking tendencies, become quite dusty when handled. Fuel oil is frequently used as a surface coat-10 ing material in order to suppress dust generation. While fuel oil exhibits some dust suppressing activity, it is not fully effective in this role, and is not a good use for an energy yielding substance.

Organic materials have been used in the past as coating materials for particulate fertilizers. Thus, Specification No.

Choi in U.S. Patent/4,259,102 discloses a heterocyclic polymer which can be used as a fertilizer coating Specification No. agent. Iwao, U.S. Patent/3,660,070, shows the use of high molecular weight polymers of the vinyl and acrylate Specification No. type as a coating agent. U.S. Patent /3,388,990 provides a very similar type of disclosure. Passmore, U.S. Patent Specification No. 3,544,297, shows polyethylene, polyvinyl chloride and , polyacrylonitrile as coating materials. Haruhiro, U.S.

Specification No.

Patent/3,475,154 discloses fertilizer particles coated with a multi-layered coating of a thermoplastic or thermosetting resin in order to provide a low water-soluble fertilizer. None of the above-discussed references oro- c vide any disclosure of either of the ingredients used in the coating agent of the present invention.

Specification No.

Hansen in U.S. Patent/3,223,518 discloses a tech- * nique of providing a slow-release fertilizer by providing 5:5 a particulate fertilizer substrate with a multi-layer coating, the outer layer being of a hydrophobic material. The reference further discloses the use of a primer coating which may be any substance selected from an extremely broad group of organic compounds. Hansen also describes that a major characteristic of the fertilizer product is its water durability which is characterized by solids which remain in the shell-like water-insoluble exterior coatings. Any fertilizer product which does not exhibit this characteristic, which includes the product 15 of the present invention, presumably is outside the scope of the reference. Moreover, the fertilizer product of the present invention is not a slow-release multi-layer coated product having a hydrophobic exterior coating.

Still further, the product of the reference possesses a 20 large amount of coating material, i.e., about 7% by weight, while the amount of coating material applied to • the present product is in most cases less than 0.1% by , i weight.

Bradley in U.S. Patent 3,951,638, discloses a prill-25 ing process which at one point uses an organosilicon compound to prevent dust pick-up by fertilizer particles. Accordingly, the reference does not show the r coating of fertilizer particles with an organic material. Assuming that the dust is an inert material, the organic material would seem to serve as a moisture barrier, which is a teaching contrary to the present invention.

Specification No.

Hijfte in U.S. Patent /4,150,965 discloses the use of an alkylamine-mineral oil combination as a coating agent for ammonium nitrate fertilizer. The reference discloses a three-step coating process, while the present process usually is/a one-step coating procedure. In the reference process an ammonium nitrate containing fertilizer is treated with the alkylamine while relatively hot, i.e., at least 5°C above the melting point of the amine or mixture containing the amine. In fact, the reference discloses that prills at 50°C cannot be coated satisfactorily, while in the present invention, on the other hand, superior coatings for ammonium nitrate can be achieved at temperatures less than 38°C. Another disclosure in the reference which is contrary to the present invention is that unadulterated alkylamine must be added to the fertilizer in the first process step. That is, the amine cannot be premixed with another compound if acceptable results are to be obtained. In the present process, an amine is, in fact, premixed with another reagent, i.e., a silicone fluid, before application to the fertilizer particles. Another difference between the reference disclosure and the present invention is that the reference does not disclose the coating procedure to be effective on fertilizers which do not contain a diluent. The working examples of the reference disclose fertilizers which contain a diluent. A need, therefore, continues to exist for a technique of providing particulate fertilizers, particularly ammonium nitrate, with an improved coating material.

Accordingly, one object of the present invention is to provide a protective coating for fertilizer particles which suppresses dusting, minimizes caking of the fertilizer particles and prill breakdown and makes handling of particulate fertilizer much easier.

Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a particulate fertilizer provided with a protective coating of the reaction product of at least one amine compound and a siloxane. In a preferred embodiment of the invention the particulate substrate is prilled ammonium nitrate fertilizer.

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when con- r \ ( sidered in connection with the accompanying drawing, wherein: the FIGURE is a flow diagram showing the mixing of coating ingredients and application of the coating material of the present invention.

Any material which is to be successful as a coating agent for particulate fertilizers must possess several desirable characteristics. The coating agent must be compatible with the fertilizer material, i.e., it must not cause deterioration of the fertilizer nor render it hazardous, .which is a particular concern with ammonium nitrate. Since the coated fertilizer is frequently handled by unprotected personnel and is applied to crop land, the coating agent must be nontoxic. In some instances where a hygroscopic salt is being coated such as in the case of ammonium nitrate, the fertilizer readily absorbs water from the ambient air. This results in caking and breakdown of the prilled fertilizer. Accordingly, an acceptable coating agent must substantially impede or eliminate moisture absorption by the particulate hygroscopic fertilizer. Another important aspect of the coating is that the coating on the particles must uniform be sufficiently/to prevent particle-to-particle contact in uncoated areas of the particles. If this type of contact is not prevented during storage of the ammoniun nitrate, c r caking of the fertilizer particles will result as bonding occurs between particles where there is insufficient coating material to prevent exposed surfaces of the particles from contacting each other. The raw materials for 5 the coating agent must be in abundant supply so that production of coated fertilizer product in volume is not impeded. The coating agent must firmly bond to the fertilizer particles from the time it is applied until the coated fertilizer is applied to the crop land. 10 Other beneficial characteristics which the coating agent should possess, but which are not mandatory, are that the cost of the ingredients on a per ton fertilizer basis should be reasonable and it should be able to be easily handled from an operational standpoint. However, 15 with regard to both of these factors, some expense and inconvenience can be tolerated as long as a superior coated fertilizer product is produced.

The coating agent of the present invention has been found to satisfy all of the above-described character-20 istics. The present coating agent is the reaction product of an amine and a polymeric siloxane.

The amine component of the present coating composition is a material which is semisolid or solid at room temperature. The amine should melt at a temperature of 25 about 43°C to about 93°C and should not decompose at these temperatures. The amine is selected from primary, secondary and tertiary, straight and branched chain ( amines of 12 to 18 carbon atoms.

Mixtures of amine may also be used, and in fact, long chain fatty amines as obtained industrially are frequently a mixture of amine compounds and are quite suitable for use in the present invention. Amine containing unsaturated hydrocarbon and aromatic 10 hydrocarbon radicals should be avoided when coating the likes of ammonium nitrate because of the increased danger of forming hazardous compositions. This is substantially much less of a factor when relatively less hazardous substrates are to be coated. A most preferred amine 15 composition is a mixture of amines having the formula: ch3-(ch2-ch2)x-ch2-nh2 wherein x is 6, 7 and 8. This particular mixture is characterized as follows: a) Solid at 24°C 20 b) Melting point (°C): 49-54°C c) Freezing point (°C): 43°C d) Specific gravity (150/60), g/cc: 0.794 e) Viscosity (66°C): 3mPa.s f) Colorless 25 g) 97% purity The siloxane reactant utilized as the other component of the coating composition should be a material which is slightly viscous at ambient temperatures or, if of higher molecular weight, should melt within the same temperature range as the amine. Alternatively, the solid siloxane should be such that it melts and homogeneously 5 blends with the amine reactant over the temperature range of about 43°C to about 93°c. The siloxane is selected from siloxanes which contain lower alkyl, lower alkoxy, lower alkylamino and/or arrrino substitution. The siloxane is preferably amine substituted, and can be polyamine substituted. The 10 siloxane should not be a hydroxy siloxane. The scope of siloxanes employable, however, includes siloxanes having cyclic structures. A preferred siloxane is amino substituted polydimethylsiloxane of the following structure: CH-, I NH2-Si-0—h Si-0 ch3 F. Accelerated Caking Test A 28 5 ml amount of coated ammonium nitrate product was placed in a cylinder designed to permit exposure of the specimen to ambient conditions. The product was compressed under a pressure of 4 psig and maintained at a temperature of 32°C and a relative humidity cycling from a high of 60% on the wet side to 2 5% on the dry side. The wet cycles were of 24 hours duration with the follow-up dry cycles being of 12 hours length except the final dry cycle which was 24 hours. The caked fertilizer sample was removed from the cylinder, placed on a compression tester and subjected to gradually increasing pressure until the cake broke. The pressure was recorded 5 at this point. Four replicate samples were run through the test and the samples were compared to duplicate samples of the reference material (usually diatomaceous earth coated ammonium nitrate prills). The caking index was calculated as the ratio of the average breaking 10 pressure of the specimens of interest to the average of the duplicate reference samples; or as the percent of reference breaking strength. This test measures the caking tendency of a fertilizer sample as a result of crystal bridging or linking of prills because of moisture absorption, moisture migration and salt recrystallization under moderate pressure.

G. T.F.I. Burn Test (72.6 Kg) A 160 pound /feample of ammonium nitrate product was (36.3 Kg) mixed with one 80 pound /size Kraft paper bag cut into about 2 inch squares. The mixture was placed on a plat- (40 cm) form grate inside the 15-3/4 inch/diameter burn chamber described in The Fertilizer Institute's official procedure for classifying ammonium nitrate. Ten pounds (5.3 Kg) of (27x5.1x20.3 cm) soft pine wood, V2" x 2 x 8"/ pieces, piled loosely in the 25 space underneath a fire grate, were ignited by a standard railroad fuse under the center of the wood pile. When the heat reached an intensity such that molten ammonium nitrate began to drop into the flames, the fire door was closed, the top of the combustion chamber was covered and dirt was piled around the fire door. This procedure leaves only ammonium nitrate as the source of oxygen.

This test is utilized for the purpose of determining how the ammonium nitrate should be classified for packaging, shipping and storage. Any product which exhibited a burning time of one hour or less may not be described as an "ammonium nitrate fertilizer" and is subject to rigid transportation restrictions.

The results of the above tests on the coated ammonium nitrate prills described above are shown in Table I.

Table I Test 24-IIr. Ball-Screen Hardness, % Single Prill Hardness, kg/cm Deformation: - % Deformation - Degree of Caking 24-Hr. Caking, psi Attrition, % Accelerated Caking, kg T.F.I. Burn Test, min.

"Similene" Coated Prills 74 13. 2 Very slight 0 1.6 .4 77 D.E. Coated Prills 100 40 11.0 Hard 50 (0.34 MPa) 19.3 479 151 Example II Two of the tests which are very important are the T.P.I. Burn Test and the 24-Hour Ball Screen Hardness Test. Of these two tests, the more critically important 5 is the burn test. The test procedure requires that a sample of ammonium nitrate fertilizer must not burn in less than 60 minutes. If the burn time is greater than 60 minutes, then the ammonium nitrate fertilizer sample may be transportation-classified as a fertilizer 10 material. It may be shipped in bulk or packaged in bags by the usual procedure of the fertilizer industry. If the burn time is less than 60 minutes, however, special packaging and handling procedures must be followed, all of which add to the cost of the fertilizer and therefore 15 are intolerable.

In early experimental work, samples of ammonium nitrate prills coated with the aminc-mineral oil combina- Specification No. tion disclosed in U.S. Patent/4,150,965 were subjected to some screening tests; and while giving good results in 20 some of the tests, none passed either the burn test or the Ball-Screen Hardness Test.

Table II below shows coating agent data and test results for a variety of coated ammonium nitrate prills. The test results show that only two coated 25 samples passed the T.F.I. Burn Test, which are the siloxane plus amine coated particles and the siloxane only coated particles. However, the prills coated only with the siloxane exhibited very poor results on the Ball-Screen Hardness Test. Moreover, the particles coated with only the siloxane material remained sticky for several hours after being coated, i.e., until the 5 slow polymerization reaction was completed. Such a coated product is unacceptable and can cause caking problems when the product is loaded into bags, hopper cars, and the like immediately after being coated.

Of all of the coated particulate compositions tested, only the ammonium nitrate particles coated with mixture an amine and a siloxane/give good results across the spectrum of tested characteristics. This result was unexpected and was not predictable.

Another advantage of the coating agent of the 15 present invention is that a satisfactory coating can be obtained in one application to a particulate substrate, while for other coatings such as the mineral oil-amine combination, coatings had to be applied in several steps to achieve a satisfactory uniform coating.

Still another advantage of the present coating com position is that it may be applied to cooled fertilizer prills, while a coating of an amine alone, or an amine . followed by another coating agent, has to be applied to hot prills. This complicates the coating process since 25 the amine is applied before the prills are cooled. It is therefore very difficult to separate the coating system from the ammonium nitrate synthesis section.

Another consideration concerning the disclosure of Specification No. the technique disclosed in U.S. Patent/4,150,965 is that a specially designed coating drum should be utilized to ensure uniform application of the amine. The flow characteristics of the present amine-siloxane coating agent are quite different from those of amine alone, and therefore an unconventional coating drum is not required.

Table II A. Coating Agent Data 1. Nomenclature a. 1st conponent b. 2nd ccnponent 2. Coating Level, wt. % a. 1st component b. 2nd component B. Test Results** 1. 24-Hr. Ball-Screen 2. Single prill, kg/an 3. Deformation: a. % Deformation b. Degree of caking 4. 24-Hr. caking, psi . Attrition, % 6. Accelerated caking, kg 7. T.F.I. Burn Test, min.

Amine-Siloxane of Exaitple I Amine+ Mineral Oil Amine Only Siloxane Only Amine+ Siloxane Siloxane+ Amine* Siloxane Amine/ Amine Amine Siloxane Amine Siloxane Siloxane mixture None Mineral None None Siloxane Amine Oil 0.03* 0.03 0.03 0.03 0.02 0.01/0.03 — 0.03 — — 0.01 0.03 74 0 52 0 64 0 32.1 28.9 39.4 28.2 29.0 13.2 9.8 11.0 8.8 .4 13.2 Very slight slight none mod. slight none 0 0 0 0 0 0 1.6 1.1 NA NA NA NA .4 .5 4.2 .9 3.3 54.6 77 51 53 150 NA 57 * Component Ratio = 70/30 (Amine/Siloxane) ** NA = Data not available Example III The data in Table III below reflect on the limitation concerning the amount of coating agent, having the composition shown in Example I, applied to the fertilizer 5 prills and the relative amounts of amine and siloxane components in the coating material. The lower preferred coating limit of 0.01% by wt. is preferred on the basis of practical handling of the coating composition, and not on the basis of actual coating performance. At coating 10 levels less than the preferred lower limit it becomes more difficult to ensure uniform coatings. The upper limit of 0.15% by wt. is preferred because the cost of additional coating material increases faster than benefits derived from additional amounts of coating agents 15 and because the coated prills retain a wet or sticky feel for some time after coating.

The upper ratio value of amine to siloxane of 95:5 is preferred because the amount of siloxane is sufficient to ensure acceptable T.F.I. Burn Test values. A coating 20 of amine alone does not pass the burn test. The lower limit of 60:40 of amine to siloxane is based primarily on material costs and performance in the Accelerated Caking Test as shown in Table III.

Table III Amine/ 24-Hour 24-Hr.

Deformation Siloxane Application B.S.H.

SPH, Caking Test % Acc.

Caking Ratio Level, % % kg/cm Test, psi deform./caking Test, kg 95/5 0.005 33.2 0 8.8/free flew 11 0.05 62 39.9 0 11.0/free flow 0 0.2 82 40.6 0 11.0/free flow 0 80/20 0.075 13 27.9 0 11.0/free flow 8 0.10 50 31.1 0 11.0/free flow NA 0.15 57 33.8 0 11.0/free flav NA 75/25 0.005 6 46.0 0 .4/very slight 0.05 27 37.0 0 13.2/free flow 6 0.2 80 41.6 0 .4/very slight 55/45 0.005 9 .1 0 13.2/very slight 54 0.05 75 34.2 0 .4/very slight 21 0.2 89 39.3 0 .4/very slight /70 0.005 91 .4 2 13.2/very slight 58 0.05 97 37.3 0 11.0/free flow 22 0.2 92 40.6 0 11.0/free flow 6 /95 0.005 17 45.5 0 6.6/free flow 39 0.05 43.9 0 8.8/free flow 19 0.2 87 44.1 0 8.8/free flow 13 NA. = Data not available Example IV Pilot Plant Results About 1000 tons of ammonium nitrate coated with the amine-siloxane coating agent of Example I were evaluated 5 in field storage tests. Fertilizer prills coated with 0.03 and 0.06 wt. % coating agent were investigated. 100 tons of bulk ammonium nitrate were stored in an un-airconditioned warehouse at temperatures in the mid-80°F (30°C) range at high humidity for about 7 weeks. The stored 10 prills at the end of this period were in excellent condition. On the other hand, it is known that diatomaceous earth coated ammonium nitrate particles begin a rapid decline after about three weeks in such an environment.

Some of the test material was transported by pneu-15 matic bulk trucks to an MCC dealer. The material unloaded very easily without the characteristic heavy dusting of diatomaceous earth coated ammonium nitrate particles. 100 ton bulk hopper cars were utilized to transport 20 some of the coated test particles. The cars were in transit for about 2 weeks during which they were subjected to hot weather with full sun most of the time. No problems were encountered unloading the cars at their destination. When diatomaceous earth coated ammonium 25 nitrate prills are transported under these conditions, hard lumps form and caking along the hopper walls occurs.

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

Table IV Sample ppm Dust Evolved Uncoated N-P-K fertilizer 53 0.2 5 wt. % oil coated N-P-K fertilizer 4 0.05 wt. % amine-siloxane coated N-P-K 12 0.2 5 wt. % amine-siloxane coated N-P-K 19 The results above show that the coating agent of the present invention provides an effective dust suppressing coating.

Example VI Table V below shows the results obtained upon coating particulate urea impregnated with formaldehyde with the present amino-siloxane coating agent in comparison to uncoated formaldehyde impregnated urea particles and unimpregnated urea particles coated with 3% clay coating.

Table V Sample 24-Hour Deformation Caking Test Test %/° Uncoated urea Urea coated with amine-siloxane 3% clay coating on urea 55 2 0 .4/slight 16.5/slight 15.4/hard *90/10 amine/siloxane ratio at 0.02% coating level The caking results with the particles coated by the amine-siloxane reagent are impressive, especially in Stability Studies on Coated Ammonium Nitrate Prills A. Burn Test Results on Amine-Siloxane Coated Ammonium Nitrate Eight samples of particulate ammonium nitrate coated with the amine-siloxane coating composition of Example I were subjected to the burning test described in Section 4.0 of "Definition and Test Procedures for Ammonium Nitrate Fertilizer" published by the Fertilizer Institute, January 16, 1973, Samples 1 to 3 had a 0.06% by wt. coating, while samples 4-8 had a 0.03% by wt. coating. The results are shown in the Table VI. contrast to clay coated urea.

Table VI Sample No. Burning Time Weight of Residue 1 1 hr. 40 mins. 7 lbs. 4 oz. (3.3 Kg) 2 59 mins. 0 53 54 mins. 0 4 2 hrs. 23 mins. 0 1 hr. 27 mins. 0 6 58 mins. 0 7 2 hrs. 40 mins. 43 lbs. 8 oz. (19.7 Kg) 10 8 1 hr. 13 mins. 0 B. Bulk Storage of Coated Ammonium Nitrate Prills Four 100 tons piles of ammonium nitrate particles 15 coated with the coating agent of Example I were stored. One pile (0.06% by weight) was stored for 11 weeks while the remaining three piles (one pile having a 0.06% by wt. coating, while the remaining two piles had a 0.03% coating) were stored for 5 weeks. The latter three piles 20 were in excellent condition after the 5 weeks. The 0.06% by wt. level pile had a soft surface crust 1-2 prills deep, composed of dry, swollen prills. Underneath the crust, the ammonium nitrate exhibited a slight set which released into whole prills using minimal force. The two 25 0.03% by wt. piles had a soft crust of (0.64 cm) or less, composed of slightly sugared and swollen prills. There was only slight set underneath the crust. There were little differences in storage features of all of the piles. All three 5 week piles were dry, despite storage under humid conditions and standing water on the warehouse floor.

The 11-week-old pile had a soft surface crust of V2 (1.3 to 2.5 cm) to 1"/. The crust formation may have been caused by ammonium nitrate and diatomaceous earth dusts on the pile surface resulting from spillage from an overhead conveyor belt.

Under the crust, the ammonium nitrate had only a slight set. The warehouse loader took a scoop from the pile, and transferred the ammonium nitrate to a load-out mechanism. The payloader action had broken the pile set so that most 15 of the ammonium nitrate in the scoop had become free- flowing. The soft cakes that remained were no problem mechanism. for the load-out / The coated ammonium nitrate of the present invention was loaded onto a waiting spreader truck with minimal dusting. The payloader cut the 11-20 week-old 0.06%-level pile in half. The section that had been moved aside broke into dry, free-flowing prills. The material toward the center of the pile was as good as that on the edge, with no noticeable concentration of fines.

A 2-week-old pile of diatomaceous earth coated prills at the warehouse had begun to form large cakes. The ammonium nitrate was damp to the touch at the sur- face, thereby comparing unfavorably with the product of the present invention. The coated samples of the present invention were characterized by their low moisture and fines content. One sample had 5.9% fines present; this 5 sample was collected by a spike probe, which can cause fines generation. A sample taken from the center of the pile only had 3.4% fines. On the other hand, in a typical diatomaceous earth coated pile in the same storage area, fines became concentrated toward the center of 10 the pile. It is not unusual to find 10-15% fines at the center of a diatomaceous earth coated ammonium nitrate pile.

The coated product of the present invention exhibited single prill hardness values of from 17-28 15 kg/cm . These values did not decrease appreciably during storage. The diatomaceous earth sample had a SPH of 23 kg/cm , which would be considered a low value based on past experience. Every sample had a low Ball-Screen Hardness value (75 balls), except for the sample taken 20 from the center of the pile of amine-siloxane coated particles.

« Sample Identification for Table VII 1. 0.06% product, made on 7/20/82; sample taken 3*(7.6 cm) 25 from floor. 2. 0.06% product made on 6/17/82; sample taken 3' (7.6 cm) from floor, with spike probe. 3. Sample as sample #2; cake taken from pile. 4. Sample as sample #2; sample taken from middle of pile, after payloader had moved through the pile. . 0.03% product made on 7/20/82; sample taken 3' (7.6 cm) from floor. 6. 0.03% product made on 7/20/82; sample taken 3' (7.6 cm) from floor. 7. DE-coated reference pile; sample taken i^' below surface.

Table VII Single Ball- Prill Screen Attrition Sample Length of Hardness Hardness Test # Storage % H00 % fines (kg/cm2) (75 balls) % fines 1 weeks 0.19 2.0 23.7 2 . 2 11 weeks 0.20 .9* 22.5 2 - 3 11 weeks 0.11 2.9 .7 0 - 4 11 weeks 0.17 3.4 27.6 67 4.0 weeks 0.17 1.2 17.3 0 4.3 6 weeks 0.17 1.6 24.4 2 4.5 7 2 weeks 0.19 3.2 22.9 1 - *Sample taken with spike probe C. Additional Coated Ammonium Nitrate Storage Results 1) Bags containing ammonium nitrate prills coated with 0.03% by wt. of the amine-siloxane mixture of Example I and stored since June 1, 1982 were removed from the first layer of a top-out pallet. The bags contained (0.6-1.3 cm) V4 ~ V2" /°f totally sugared ammonium nitrate powder on the exposed face. These prills had been affected by temperature cycling near the warehouse ceiling. The bag contained whole, free-flowing ammonium nitrate prills below the sugared portion. Prill breakdown was not at other layers of the top-out pallet. The remaining top-out bags had a slight set that released when handled, and contained a small amount of very soft cakes as shown in 5 Table VIII blow.

The quantity of caking increased at the middle pallet. These cakes were very soft, and broke when handled. The most caking was seen at the bottom pallet. The cakes were very soft on the bottom pallet 10 until the 9th (next-to-last) layer was reached. At this layer, the cakes were a mixture of soft and moderate caking.

Table VIII Number of Bags Pallet/Layer Sampled % Caking Cake Hardness % Fines Top-out/1st 2 - 1.2 Top-out/3rd 2 1.8 very soft 0.8 Top-out/5th 2 1.0 very soft 1.1 Middle/3rd 2 7.5 very soft 0.8 Middle/7th 2 18. 5 very soft 0.7 Bottom/2nd 2 44. 3 very soft 1.0 Bottom/5th 3 r- CO H very soft - Bottom/9th 4 36.8 (2/3 moderate; — Pallet/Layer Top-out/3rd 1/3 soft) Single Prill Hardness (kg/cm ) 22.4 Ball-Screen Hardness (75 balls) Middle/3rd 19. 5 Bottom/2nd 26.6 2) Bags containing ammonium nitrate prills coated 25 with 0.06% by wt. of the amine-siloxane coating mixture of Example I and stored since June 17, 1982, which were removed from the first layer of the top-out had 1 V2 ~ 2" (3.8-5.1 c of powdered and softly caked ammonium nitrate along the (1.3 cm) exposed face. Only the top V2"/Was powdered, the remainder caked. Below the caked portion, the prills were whole and free-flowing. Prill breakdown was only 5 observed on the first layer of the top-out. There was a large quantity of caking throughout the remaining top-out bags. The cake hardness varied from soft to moderate as shown in Table IX below.

The amount of caking remained high throughout the middle and bottom pallets, ranging from 36-74% by wt. The cakes were of moderate hardness. An individual would have had to drop these bags several times to break up the cakes.

This material was produced in the second hour of the ^ June 17 plant test, and had noticeable amounts of DE on the prills. Also, a faint ammoniacal odor was noticed as the bags were cut open. These factors could adversely affect storage.

Table IX Number of Bags Pallet/Layer Sampled % Caking Cake Hardness % Fines Top-out/lst 2 Top-out/3rd 2 Top-out/5th 2 Middle/3rd 2 Middle/7th 2 Bottom/2nd 2 Bottom/5th 2 Bottom/9th 2 50.3 soft 68.3 (2/3) moderate; (1/3) soft 52.7 (2/3) moderate; (1/3) soft 43.7 moderate 66.4 moderate 52.5 moderate 73.9 moderate 36.4 moderate 1.4 1.0 Note: This ammonium nitrate was produced in 2nd hour of plant test. There was a good deal of diatomaceous earth on the material, which could adversely affect storage.

Pallet/Layer Top-out/3rd Middle/3rd Single Prill Hardness (kg/cm ) 28.2 21. 7 Ball-Screen Hardness (75 balls) 1 2 3) First layer top-out bags containing ammonium nitrate prills coated with 1.5% by wt. diatomaceous earth (5.1 cm) and stored since May 31, 1982 had 2"/of moderately caked prills along the exposed face. Below the caked portion, the prills were free-flowing. There was no sugaring noticed in the first layer bags. The remaining top-out bags contained small amounts of soft cakes. The quantity of caking was more than seen with equivalently positioned 0.03% amine-siloxane coated ammonium nitrate prills in a bag as shown in Table X below.

The quantity of caking increased slightly at the middle pallet, with soft cakes present. These bags would not have presented problems to a consumer.

The most caking was found at the bottom pallet, ranging from 42-66% by weight. Cake hardness was moderate throughout the bottom pallet. The bags would have to be dropped on the floor several times to break up the cakes.

In considering these results, it must be realized that this product was made on a very cool day, and represents the "best case" situation.

Table X Number of Bags Pallet/Layer Sampled % Caking Cake Hardness % Fines Top-out/lst 2 .3 moderate 0.8 Top-out/3rd 2 2.6 soft 1.0 Top-out/5th 1 11.9 soft - Middle/3rd 2 14.8 soft 0.7 Middle/7th 2 24.7 soft - Bottom/2nd 2 42. 3 moderate - Bottom/5th 2 65.7 moderate - Bottom/9th 2 CO i-^ in moderate — Pallet/Layer Top-out/3rd Middle/3rd Bottom/2nd Single Prill Hardness (kg/cm ') 19.9 25.6 22.8 Ball-Screen Hardness (75 balIs) 73 36 68 " 41 -

Claims (24)

1. A particulate fertilizer provided with a protective coating, 5 comprising: particles of a fertilizer coated with the reaction product of at least one amine compound which is a primary, secondary or tertiary, straight or branched hydrocarbon chain amine of 12 to 18 carbon atoms and a siloxane having lower alkyl, lower alkoxy, lower alkylamino and/or amino substitution. 10

2. The fertilizer of Claim 1, wherein said amine is a single compound or mixture of amines which melts at a temperature of 43°C to 93°C. 15

3. The fertilizer of Claim 2, wherein said amine is a single compound or mixture of amines which are primary, secondary or tertiary, straight or branched chain amines of 12 to 18 carbon atoms.

4. The fertilizer of Claim 3, wherein said amine is a mixture of 20 compounds of the formula: ch3-(ch2-ch2)x-ch2-nh2 wherein x is 6, 7 and 8. 25

5. The fertilizer of Claim 1 wherein said siloxane is slightly viscous at ambient temperatures.

6. The fertilizer of Claim 5 wherein said siloxane is amino 30 substituted and contains lower alkyl and/or lower alkoxy substituents. 35

7. The fertilizer of Claim 6, wherein said siloxane has the formula: CH, i3 NH2— Si— 0- CH. CH, I 3 Si—0 CH, CH. I * -Si I CH. -NH, -42- wherein x is such that said siloxane has a viscosity of about 0.53 g/cm sec at ambient temperature.

8. The fertilizer of Claim 1, wherein the weight ratio of amine 5 to siloxane in said coating ranges from 5:95 to 95:5.

9. The fertilizer of Claim 8, wherein said range is 70:30 to 90:10.

10. 10. The fertilizer of Claim 1, wherein the amount of coating on said fertilizer particles ranges from 0.005% to 0.20% by weight.

11. The fertilizer of Claim 9, wherein the amount of said coating ranges from 0.01-0.05% by weight. 15

12. The fertilizer of Claim 1, wherein said fertilizer particles are ammonium nitrate prills.

13. A method of providing fertilizer particles with a protective 20 coating, comprising: contacting a liquid reaction product of at least one amine compound which is a primary, secondary or tertiary, straight or branched hydrocarbon chain amine or an amine containing a cyclic hydrocarbon radical and a siloxane having lower alkyl, lower alkoxy, lower alkylamino and/or amino substitution at a temperature of 16°C 25 to about 110°C with fertilizer particles for a time sufficient to obtain a uniform coating on the fertilizer particles.

14. The method of Claim 13, wherein said reaction product is applied to said fertilizer particles at a temperature ranging from 30 54° to 93°C.

15. The method of Claim 13, wherein the amount of said reaction product applied to said fertilizer particles ranges from 0.005% to 0.2% by weight. 35

16. The method of Claim 13, wherein said fertilizer particles are ammonium nitrate prills. - 43 -

17. The method of Claim 13, wherein the ratio of amine to siloxane in said coating ranges from 5:95 to 95:5.

18. The method of Claim 13, wherein said coating mixture has a 5 viscosity of less than about 0.1 g/cm sec under operating temperature conditions.

19. The method of Claim 13, wherein said amine is a single compound or mixture of amines which are primary, secondary or tertiary, 10 straight or branched chain amine compounds of 12 to 18 carbon atoms.

20. The method of Claim 13, wherein said siloxane is amino substituted and contains lower alkyl or lower alkoxy substituents and is slightly viscous at ambient temperatures. 15

21. A method of providing fertilizers with a protective coating substantially as described herein with reference to any of Examples 1 to 6. 20

22. A method of providing fertilizers with a protective coating substantially as described herein with reference to and as shown in the accompanying drawing.

23. A particulate fertilizer provided with a protective coating 25 substantially as described herein with reference to any of Examples 1 to 6.

24. A fertilizer with a protective coating whenever produced by a method as claimed in any of Claims 13 to 22. 30 Dated this 22nd day of May 1984. BY: Tomkins & Co. 35 4fppTTfcs(its1 Agents (Signed) 5 Dublin 6 Dartmouth Road -44-