GB2112765A - Fertilizers - Google Patents

Abstract

A fertilizer product in granular form, is characterised by containing as active constituent a nitrogen source selected from melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof. The granules have strength, sizes and weights suitable for mechanical dispensing and application to the soil.

Description

SPECIFICATION Fertilizer compositions, processes of making them and processes of using them Background of the invention This invention relates to a new fertilizer product in composite granular form, to a process for making it, and to a process for using it. More particularly, the invention relates to a granular fertilizer product in which the granules have strength, sizes, and weights suitable for mechanical dispensing and application to and into the soil. These new fertilizer granules provide a novel combination of fine particles: a particulate nitrogen source such as melamine together with a binder such as a urea suitable for binding the particulate nitrogen source into granular form.

Ammonia, ammonium nitrate and urea are among the most commonly used sources of nitrogen but all of these nitrogen fertilizer materials are readily soluble in water. They are therefore subject to leaching, and their use results in a rapid release of their nitrogen. Since this necessitates repeated applications for sustained growth, or one application with higher leaching losses, there have been many developments relating to slow release nitrogen fertilizer materials. Generally such'materials sacrifice nitrogen content for some degree of control over nitrogen availability.

Melamine and its hydrolysis products, ammeline, ammelide, and cyanuric acid, have been considered as potential sources of nitrogen for incorporation in fertilizer compositions or for utilization as nitrogen sources per se. Melamine has a nitrogen content of 66.6%. If it could be used as a fertilizer material, it would provide a good deal of nitrogen per unit weight applied. However, at present it is more expensive than urea.

Moreover, commercially produced melamine is available only as fine crystalline powder. It is manufactured in the form of very fine crystals because small size particles are required for the present commercial end markets for melamine, such as, for example, the production of melamine-formaldehyde resins and the production of fire retardant paints.

A typical screen analysis for one commercially available melamine, conducted with United States Standard Sieve screens, is as follows: Percent Screen Analysis Retained 40 Mesh 0-0.1 40-50 Mesh 0-0.1 50-60 Mesh 0-0.3 60-80 Mesh 0.5-5.0 80-100 Mesh 1.0-5.0 100-200 Mesh 13-30 200-325 Mesh 13-30 Thru 325 Mesh 40-60 The commercially-produced small melamine crystals are desired by the resin producers because the small crystals dissolve more readily, and any larger particles, if present, would tend to require a longer processing time; therefore, the larger particles are less desirable. In the fire retardant paint market, the melamine crystals are dispersed in the paint, where the currently used fine particle sizes produce a smoother texture in the dried paint than would larger particles.

The fine particle sizes of the commercially available melamine products make melamine a product that is not very attractive for agricultural applications. Moreover, the fine particle sizes of commercial melamine as currently produced, make it impractical to use a fertilizer material. The fine particles, if applied to the surface of the ground, would be blown away by even mild winds. If applied by air, as from an airplane or helicopter, drifting would be a serious problem and would cause uneven application. If applied through mechanical applicators, the fine particles would tend to form bridges and thus would plug transfer and dispensing lines.

These difficulties in handling the commerically available melamine solids would make any large scale agricultural application impractical.

Summary ofthe invention In one of its aspects, this invention resides in a fertilizer product in granule form. The fertilizer granules have strength, sizes, and weights that are suitable for dispensing mechanically for application to and into the soil. The preferred size range is from about 1 millimeter to about 10 millimeters, and the most preferred size range is from 3 mm. to 5 mm.

These fertilizer granules comprise a particulate nitrogen source and a binder. The nitrogen source is characterized by fine particle sizes not above about 10 mesh, by poor solubility in pH7 water at 200C, and by slow conversion in the soil to a form in which it is useful to plant life growing in the soil. The nitrogen source is selected from the group of materials consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts and mixtures thereof. The binder is present in an amount at least sufficient ta bind together the fine crystals or powder particles of the nitrogen source, to form granules having the desired strength.It is preferably a readily soluble material that, after distribution of the granules in the soil, releases the nitrogen source particles to permit the action of water and microorganisms on the particles. The binder is selected to be compatible with the soil, and any residue of the binder should be either inert, biodegradable, soil conditioning or have plant nutrient value.

The binder is selected from the group of materials consisting of urea, ammonium sulfate, potassium sulfate, ammonium nitrate, ammonium phosphate, potassium nitrate, potassium chloride, ammonium chloride, potassium dihydrogen phosphate, lignin sulfonate, urea formaldehyde resin, melamineformal- dehyde resin, starch, latex and mixtures thereof.

In a preferred embodiment the granules comprise up to 80 parts by weight of the particulate nitrogen source and at least 20 parts by weight binder.

In a more preferred embodiment the granules comprise from 60 to 80 parts by weight melamine and from 20 to 40 parts by weight urea. In another preferred embodiment the granules comprise from 67 to 80 parts by weight melamine and from 20 to 33 parts urea. In a most preferred embodiment the granules comprise about 67 parts by weight melamine and about 33 parts by weight urea.

In another aspect this invention resides in a granule prepared by a process having an annealing step to provide enhanced strength to the granule and adapting them for use as a source of nitrogen for fertilizing applications. This process involves mixing a particulate nitrogen source selected from the group of materials listed above with an effective amount of a binder suitable for binding the nitrogen source particles into granules having sizes and weights suitable for mechanical application. The mixture is then contacted with a spray of water or an aqueous solution of the binder. The moistened mixture is aggolmerated, dried and annealed.In a preferred embodiment the process requires a drying temperature of less than 93"C and an annealing temperature between 135"C and 14900. In a most preferred embodiment this granule is prepared from a mixture of from 50 to 80 parts by weight melamine and from 50 to 20 parts by weight urea.

In another aspect of this invention is a fertilizer in prill form. This prili is prepared by mixing an effective amount of a molten binder selected from the group of binder materials listed above with fine powder particles of a particulate nitrogen source selected from the group listed above. Drops of this mixture are then chilled to form prills. In a preferred embodiment this prill comprises from 40 to 65 parts by weight melamine as the particulate nitrogen source and from 35 to 60 parts by weight urea binder. In another preferred embodiment this prill comprises 50 to 60 parts by weight melamine and 40 to 50 parts by weight urea.

In another embodiment this invention involves a process of preparing a fertilizer product in granular form adapted for use as a source of nitrogen for fertilizing applications. This process involves mixing a particulate nitrogen source selected from the group listed above and an effective amount of a binder selected from the group listed above. The process involves contacting the mixture with a spray of water or an aqueous solution of the binder, agglomerating the moistened mixture to form agglomerates and drying the agglomerates. The agglomerates are screened to produce product agglomerates having sizes in the range of 1 millimeter to 10 millimeters, preferably. Over-sized particles can be crushed to size, and fines can be recycled.

In another preferred embodiment the process requires mixing from 50 two 80 parts by weight melamine with from 50 to 20 parts by weight urea binder. In a most preferred embodiment this process involves mixing about 67 parts by weight melamine with about 33 parts by weight urea.

In another embodiment this invention involves a process for preparing a granular agglomerate adapted for use as a source of nitrogen for fertilizing applications which involves an annealing step following and in addition to the mixing, contacting, agglomerating and drying steps of the process described above. In a preferred embodiment this invention involves drying the agglomerates at a temperature less than 93"C and annealing the dried agglomerates at a temperature between 135"C and 149"C. In another preferred embodiment this process comprises mixing from 50 to 80 parts by weight melamine and 50 and 20 parts by weight urea. As a rule, crush strengths of 1000 grams or greater are attained where the annealing step of heating to 135"C to 1490C is carried out on the granules made from melamine and urea.

In another aspect this invention is a process of fertilizing crops comprising dispensing to the soil a granular product comprising a particulate nitrogen source selected from the group listed above and an effective amount of a binder selected from the group of binders listed above. In a preferred embodiment this process involves dispensing to the soil a granular product comprising up to 80 parts by weight of the particulate nitrogen source and at tease 20 parts by weight binder. In a most preferred embodiment this process involves dispensing a granular product comprising up to 80 parts by weight melamine and at least 20 parts by weight urea.

In another aspect this invention is a process of fertilizing crops which involves dispensing to the soil a granular product having strength, size and weight suitable for mechanical dispensing and application formed by mixing an effective amount of a binder selected from the group of binders listed above and a particulate nitrogen source selected from the group of nitrogen sources listed above. After the mixing step the process involves contacting the mixture with a spray of water or an aqueous solution of binder, agglomerating the moistened mixture to form agglomerates, drying the agglomerates and annealing the dried agglomerates. In a preferred embodiment this process comprises mixing melamine as the particulate nitrogen source with a urea binder. In another preferred embodiment this process involves fertilizing a crop of corn, potatoes or rice.

In these processes of fertilizing crops, the total rate of application is such as to insert enough total long term fertilizer nitrogen for an entire growing season. A primary advantage of this process, and of the use of the composite granular fertilizer prepared in accordance with the invention, is that the rate of application of the fertilizer generally is less than one-half of that needed to achieve comparable results when ammonium sulfate is employed as the sole source of nitrogen and is applied as a solution through an irrigation sprinkler system.

In another aspect this invention is a process of furnishing a slow release source of fertilizer nitrogen to field soil as a nutrient source for a crop by inserting and distributing in the soil in the root zone in particulate form a fertilizer nitrogen source that is characterized by poor solubility in pH 7 water at 20"C. This slow release nitrogen source may be melamine, ammeline, ammelide, cyanuric acid, their organic or inorganic salts or mixtures thereof. After applying the solid form of the nitrogen source on the surface of the soil a portion of the soil is turned over to insert and distribute the fertilizer at the desired depth range throughout the soil.

In another aspect this invention is a process of applying the slow release nitrogen source described above in the form of a slurry of solids suspended in an effective amount of a liquid vehicle for the nitrogen source that permits application of the slow release fertilizer particles to and their distribution in the soil.

Definitions The term "poorly water soluble" refers to materials that dissolve in water at 20"C, pH7, to the extent of 5 grams per 100 grams, or less; that is, materials that form solutions of 5% or less concentration. The term "poor sqlubility" in pH 7 water at 20"C has the same meaning.

The term "readily water soluble" refers to materials that dissolve in water at 20"C, pH 7, to the extent of 20 grams per 100 grams or more, that is, materials that form solutions of 20% or greater concentration.

Based on available information, the solubilities in water at 20"C, pH 7, for several materials useful in connection with this invention, in grams per 100 grams are: TABLE I Solubility Data Material 9/1009 melamine 0.50 ammeline 0.008 ammelide less than 0.008 cyanuric acid 0.27 melamine nitrate 0.85 ammonium nitrate 192 ammonium sulfate 75.4 diammonium phosphate 131 (at 15 ) potassium acid sulfate 51.4 potassium sulfate 11.1 urea 119.3 (at 2500) Detailed description of the invention fertilizer products in accordance with the present invention are in granular form, with sizes in the range from about 1 mm. to 10 mm., preferably 3 mm. to 5 mm. They are made up to have good drillability, a desirable apparent specific gravity, and to be substantially free from dusting.The granules are also made to be suitable for mechanical dispensing and application to and into the soil using modern tools.

Granular fertilizer products made in accordance with preferred embodiments of the invention may be in the form of agglomerates or prills. The agglomerates may be made by any conventional technique for agglomerating fertilizer products, utilizing the poorly or slightly soluble fertilizer nitrogen sources of the present invention, followed by an annealing treatment to provide sufficient crush strength. Thus, the poorly or slightly soluble nitrogen source in an agglomerate is selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof.These salts are preferably selected from the group consisting of the hydrochloride, hydroiodide, metaphosphate, nitrate, orthophosphate, orthophosphate dihydrate, polyphosphate, potassium dihydrogen phosphate, bisulfate, and sulfite, and, as well, the acetate, cyanurate, chloroacetate formate, benzoate, fumarate, lactate, maleate, and phthalate, and mixtures thereof. These materials are characterized by poor or slight solubility in pH 7 water at 20"C, and by slow conversion in the soil to a form in which the nitrogen is useful to plant life growing in the soil.

These nitrogen source materials, as ordinarily available commercially or as prepared, are in the form of very fine particles. In the case of melamine, for example, the commercially available product typically has crystalline particles that are smaller in size than 10 mesh, U.S. Standard Sieve size, and generally, mostly smaller than 40 mesh. These very fine, powdery nitrogen source materials are agglomerated through the use of a binder. Generally the binder forms at least 1% by weight of the powdery particles, preferably at least 2% by weight of the powdery particles, and more preferably, at least 5% by weight of the powdery particles.The binder may be selected from a broad spectrum of materials, but preferably is selected to be compatible with the soil so that it and any residue thereof is either inert, biodegradable, soil-conditioning, or has some plant nutrient value.

The binder that is used should be sufficiently strong, upon hardening or curing, to impart to the granular agglomerates a crush strength of at least 454 grams, as determined by tests on ten agglomerates randomly selected, with sizes in the range from 3 mm. to 4 mm., the results being averaged. Preferably, however, the crush strength is at least 680 grams, and more preferably, 908 grams or higher. A crush strength of about 454 grams is comparable to conventional, commercial prilled urea and is adequate strength for use in most forms of commerical application, including broadcast devices, spreaders, planter shank applicators, and for dispensing from airplanes and helicopters.

Among the preferred binders are those selected from the group consisting of lignin sulfonate and its salts, starch, urea, urea-formaldehyde resins, melamine-formaldehyde resins, and latices of synthetic polymeric materials. Those binders are most preferred that have plant nutrient value, as do urea, urea-formaldehyde and melamine-formaidehyde resins.

In one preferred agglomeration technique, the melamine power is combined with from 5% to 25% by weight of powdered urea to form a blend. This blend is then sprayed with water or with a solution of urea, in an agglomerating device such as on a rotating disc or in a rotating drum. In the case of a binder solution, the particles are coated. In the case of a water spray, the urea either goes into solution or becomes moistened and tacky, and in either state, coats the powdery melamine particles sufficiently to cause aggolmeration to occur. The agglomerates are dried and cooled, to form hard composites having sizes primarily in the rante from about 1 mm. to about 10 mm., and preferably 3 mm. to 5 mm. These composites have good crush strength and are substantially free from dusting.

Any of the conventional agglomerating techniques can be used. Thus, all of the binder can be applied in solution. When the binder is a material such as iignin sulfonate, urea-formaldehyde resin, or melamineformaldehyde resin, application in the form of a solution is usually most convenient. The binder might also be a material such as a phenolic resin, applied from a solution, but such a material, while having excellent characteristics as a binder, has no nutrient value to contribute and is therefore less desirable. The same considerations apply to synthetic polymer latices.

The fertilizer particles of the invention may also be made in the form of prills. In the prilling operation, melamine powder is added to a molten binder material, preferably urea, to form a slurry of the melamine powder particles in the molten urea. Droplets of this molten slurry are solidified by dropping them through a prilling tower, in the conventional fashion. While urea is the preferred material for use in preparing prills, because of its nitrogen content and ready solubility in water, and also because melamine is somewhat soluble in molten urea, other material such as sulfur could also be used, and mixtures of materials could be used. In forming urea-bound prills, it is preferred that the prill product contain at least 33% by weight of urea.

When less urea is present, it is difficult to prepare a flowable slurry. The urea content of the prill may be as high as 90%, so that the melamine content may be in the range from 10% to 67% by weight of the prills.

Preferably, the urea content is from 35% to 60% by weight of the prills, and more preferably, from 40% to 50% by weight.

While preferred granular products are produced by agglomeration and prilling, satisfactory products can be produced by other technique, including extruding techniques, pressing and granulating, and bricquetting.

For example, melamine power, or a powdered melamine salt, or the like, can be combined with a urea formaldehyde resin in powder form to form a mixture. The mixture can be pressed at an elevated temperature to cure the resin, and the resulting product can be granulated to form particles of the desired size, or the pressed, cured mass can be converted to flake form. Screening and recycling can be used as necessary to develop granules of the desired sizes.

Readily soluble binders such as urea and salts such as amonium nitrate permit rapid disintegration of the binder of the fertilizer granules in the soil, with release of the fine melamine or other fine particles. This may be desirable where the composite contains not only melamine but also a readily soluble, fast release nitrogen fertilizer material. Where slow release is desired, then ordinarily one of the binders is employed that loses binding power more slowly in the soil, such as, for example, a urea-formaldehyde resin or a melamine-formaldehyde resin.

Urea is a preferred binder for agglomerates, or for making prills, because it not only permits the production of fertilizer granules of sufficient size, strength, and weight, for convenient application, but in addition, the urea is readily soluble and adds valuable fast release nutrient material to the soil. When used with a powdered nitrogen source characterized by poor or slightly solubility and slow conversion in the soil to a useful form, the urea dissolves rapidly and releases the fine particles of the poorly soluble nitrogen source into the soil, for slow dissolution or biodegradation.

When an agglomerate is prepared from powered melamine and a readily water soluble binder such as urea, preferred pro-portions in the dried granular product obtained are from 6b% to 85% by weight of melamine and from 40% to 15% by weight of urea, or more preferably, from 67% to 80% by weight of melamine and from 33% to 20% by weight of urea. The most preferred granule comprises about 67 parts by weight melamine and about 33 parts by weight urea.

When an agglomerate is produced using an insoluble or only slightly soluble binder such as starch, a derivatized starch, or a modified starch, lignin sulfonate, urea-formaldehyde, or melamine-formaldehyde, or one of the non-nutrient materials such as a phenolic resin, or a synthetic polymer in the form of a latex, a very slow release of nitrogen from the melamine particles (or particles of other poorly soluble nitrogen source) is obtained.

In a preferred embodiment, from 85 to 99 parts by weight of the particulate nitrogen source is combined with from 1 to 15 parts by weight of a resinous binder selected from the group consisting of lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, latex, or mixtures thereof. In a more preferred embodiment 95 parts by weight of melamine and 5 parts by weight of the listed resinous binders are combined.

For the production of an agglomerate permitting a single application per growing season, fast release nitrogen fertilizer materials, generally an ammonium salt or urea, are advantageously used as the binder of the agglomerate. Examples of such salt-type binder materials are ammonium sulfate, potassium sulfate, ammonium phosphate, diammonium phosphate, the potassium phosphates, ammonium nitrate, potassium nitrate, potassium chloride, and ammonium chloride. When used as a binder material in the formation of an agglomerated composite, the proportion of such salt-type binder material may be from 15% to 40% by weight of the agglomerate, and preferably is from 20% to 33% by weight of the agglomerate.

In addition, other materials may be incorporated in a granular fertilizer product prepared in accordance with the invention. Such materials may be micronutrients such as zinc, magnesium, iron and boron.

One of the advantages of the use of granular fertilizer compositions prepared in accordance with the present invention is that the rate of application may be much lower in terms of nitrogen applied per acre than is true with standard fertilizer practice. Because less of the active material is actually needed, it may be desirable, to facilitate application, in some cases, to incorporate an inert filler. Any of the conventional filler materials may be employed, such as, for example, gypsum, clay, sand, ground sea shells, ground dolomite, and ground limestone.

Another important advantage of the use of granular fertilizer products in accordance with the present invention is that, because of the slow release characteristics, it is possible to employ only a single application per growing season. In addition, after the initial application, in the case of melamine based fertilizer products in particular, the release of nitrogen values into the soil appears to continue over two growing seasons.

Consequently, in the second and subsequent growing seasons, even lower rates of application may be employed for given results, than may be used for the initial application.

Another aspect of the invention is the unexpected and surprising finding that furnishing a majority or all of the nitrogen fertilizer requirement by a nitrogen fertilizer source in accordance with the present invention apparently leads to a more effective production of agricutural productive units per unit weight of nitrogen applied, and per unit of growing area. An agricultural productive unit is a seed, fruit, flower, vegetable, vegetable fiber, tuber, or the like. In addition, the practice of the invention apparently leads to overall yields of plant units comparable to those obtained when following conventional, standard fertilizer practice, with its requirement for the use of much higher nitrogen fertilizer application levels.

In a broad terms, this invention may be considered, in one example, as a process for increasing the effectiveness of standard readily soluble, fast release nitrogenous fertilizers in generating productive units in agricultural crops by supplementing their action with the use of a slow release, poorly or slightly soluble fertilizer nitrogen source. Thus, a combination of from about 10% to about 50% of the nitrogen in a standard readily water soluble, fast release nitrogenous fertilizer may be combined advantageously with from about 50% to 90% of poorly soluble materials recited above.

The agricultural crops expected to respond to treatment in accordance with the invention include substantially all crops, but particularly those where fruit is the harvested unit rather than the entire plant.

Such crops include food grains, feed grains, legumes, fibers, root crops, citrus, tubers, oil bearing units including nuts, fruits and seeds, commercial vegetables, commerical melons, tree fruits, vine fruits, bush fruits and flowers. Exemplary food grains include wheat, rye, and rice. Feed grain crops include field corn, oats, barley and sorghum. Legumes include soybeans, peanuts, beans and peas. Fiber crops include cotton, hemp and jute. Root crops include sweet potatoes and sugar beets. Citrus crops include oranges, tangerines, grapefruit, lemons and limes. Tuber crops include potatoes. Oil crops include flax, safflower, sunflower, and castor bean. Commercial vegetable crops include lima beans, snap beans, beets, carrots, sweet corn, cucumbers, onions, green peas, and tomatoes. Commercial melon crops include cantaloupes, honeydews and watermelon.Tree fruit crops include apples, peaches, pears, cherries, and plums. Vine fruits include grapes. Bush fruits include the many different kinds of berries, especially raspberries and blueberries. Tree nut crops include almonds, filberts, pecans and walnuts. These are intended to be exemplary only.

The invention will be better understood by reference to the following examples. Throughout this application and in these examples, all reference to parts and percentages are by weight, and all references to temperatures are in degrees Celsius, unless expressly stated otherwise.

Examples of the formation of granules that are useful in the process of the invention In all of the following examples, the melamine used was the commercially available product of Melamine Chemicals, Inc., Donaldsonville, Louisiana. It was a fine white crystalline powder having a screen analysis substantially as reported above for commercially available melamine. It was about 99.9% pure, with specifications of a maximum moisture content of 0.1%, maximum ash of 0.01%, and a density of about 1.57 g/ml.

As is pointed out in some of the following examples, crush strengths of 454 grams or greater are preferred.

More preferably crush strengths of 1362 grams or more are developed, to facilitate application. Also, the bulk density of the granules should be 40 Ibs./ft3 or more. The preferred combination of bulk density, crush strength, and particle size makes for flexibility in and ease of application. Usually crush strengths of 1000 grams or greater are attained when the annealing step of heating to 1350C to 149"C is carried out on the melamine urea granules.

EXAMPLE I Melamine agglomerates using a urea binder Three batches of composite granules were made up, each containing different amounts of urea and melamine, with urea serving as the binder. These batches of agglomerated granules were made in a pan agglomerator of 9" diameter. The urea was first ground, and then blended with the melamine powder to form a homogeneous mixture. The powder mixture was fed to the pan agglomerator and sprayed with a nearly saturated solution of urea and water. The solution added about 7% urea to the dried agglomerate. The remainder of the urea content was derived from the urea powder in the urea-melamine powder mixture.

EXAMPLE II Annealed melamine granules A batch of granules was prepared using 67 parts of melamine crystals and 33 parts urea. The granules were made on an 18 inch disch pelletizer. The urea was first ground, then blended with the melamine to form a homogenous mixture. This mixture was fed to the pelletizer and sprayed with water. The granules were dried at 200"F (94"C) for about 20 minutes and then were subjected to a further step of heating in a laboratory oven to 149"C for 3 minutes. After cooling, the crush strength and rate of breaking apart in water were measured. These values are reported in Table I below TABLE I Crush Strength Time to Disintegration (grams) in Water Example 1 600 immediate Dried Granules Example II 2400 20 to 30 seconds Annealed Granules This Example illustrates the relationship between time and temperature in the annealing step.

EXAMPLE Ill Annealed melamine granules Melamine granules prepared according to Example II were heated in separate batches at 104"C, 149"C, and 172"C for varying times. A standard laboratory oven was used. After cooling, the crush strength was measured. The results appear in Table II. The maximum crush strength at 172"C appears at 6 minutes heating. The maximum crush strength appears at 149"C at 11 minutes heating. Shorter drying times and annealing times will be possible in production when forced air dryers or ovens will be used in place of the laboratory oven used in these examples.

TABLE II Oven Temperature Minutes Crush Strength "C Heating (grams) 104"C 20 560 149"C 4 350 5 881 6 978 7 1333 8 1290 9 1530 10 1480 11 1780 12 1300 13 1640 14 1445 15 1530 20 1454 172 C 4 763 5 1125 6 1340 7 1200 8 825 EXAMPLE IV Melamine agglomerated with urea powder; water spray One batch of agglomerated granules was prepared in a pan agglomerator as in Example 1, except that all of the urea was added as a powder, and the spray applied at the pan consisted only of water. The resulting composites contained 80% melamine and 20% urea, and after screening to 3-4 mm., were found to have a crush strength of 953 g. using the same testing technique as in Example I.

EXAMPLE V Use of other binders for agglomerating melamine Granular agglomerates were prepared with a 16 inch pan agglomerator using melamine with several different binders. In each case, the binder, in liquid form, was sprayed on the melamine. After drying crush strength was determined as in Example I. The results are reported in Table III, below.

TABLE III Crush strengths observed Melamine agglomerated with different binders Crush Strength, grams of 3-4 mm.

Binder Agglomerates Calcium lignin sulfonate1 908 UCAR 368 latex1 681 Melamine-formaldehyde resin1 1544 Urea-formaldehyde resin 1 454 Diammonium phosphate (DAP)2 91 Ammonium nitrate2 150 1Applied at 30%-50% solids. The dried agglomerates were about 5% binder.

2Substantially saturated solutions used. The dried agglomerates were approximately 93% melamine, 7% salt.

EXAMPLE VI Melamine agglomerated with other fertilizer materials Melamine, ammonium phosphate, and potassium chloride were blended together in a 70:15:15 weight ratio. The mixture was fed to a 16 inch pan agglomerator and sprayed with a 30% solids lignin sulfonate solution. The dried, screened granules had a crush strength of 1000 grams in the 3-4 mm. size range, and a binder content of 3%.

EXAMPLE VII Melamine in matrix of solidified urea binder Melamine and urea powder were blended in a 63-37 ratio. The blend was heated until a molten slurry was obtained. The slurry was then poured onto a cooling slab so as to form both a thin film and a thick film. After cooling the thin film was broken into flakes.

The thick film, of about 4 mm. thickness, was broken into granules. The crush strength of the 3-4 mm.

granules was exceptionally high, at 2500 grams.

EXAMPLE VIII A pressed melamine-urea composite A melamine-urea blend was formed as in Example VII. This blend was then placed in a heated platen press at about 500 psi for 5 minutes, at 138"C. The resulting hot composite, in the form of a sheet about 4 mm, thick, was then removed from the press and allowed to cool. The cooled sheet was granulated, and 3-4 mm.

granules of the composite had a crush strength of 2500 grams.

EXAMPLE IX Melamine-urea 60140 prills Melamine composite prills were prepared by heating 40 parts urea by weight with 60 parts melamine by weight. Heating was done in an aluminum can using electric heating tape. A slurry formed at 135"C. Holes were then punched in the can bottom, allowing the slurry to drip. A plastic sheet spread on the ground caught the falling prills as they dropped from the fourth story level.

The largest prills did not cool before landing and smashed. However, the smaller prills cooled and solidified, and were collected for strength testing. Fairly good strength results were achieved, although not measured. Crush strength would be expected to be similar to the granules of Example VII.

EXAMPLE X Melamine agglomerated with a latex binder 5% Union carbide UCAR 368 Latex, 15% water, and 80% melamine were combined into a flowable slurry. A sheet of the slurry was formed and then dried. An extremely strong composite resulted which could be granulated. The dried material contained 3% latex solids and 97% melamine. The crush strength of 3-4 mm.

granules was 2180 grams.

EXAMPLE XI Pressed composite of melamine and ure-formaldehyde 25 grams of urea, 70 grams melamine, and 15 ml. of 27% formaldehyde solution were mixed together and pressed at 149"C and 500 psi to form a thick sheet. Crush strength of 3-4 mm. granules was 680 grams.

EXAMPLE XII Melamine-urea agglomerates for field trials For field trials, 16,000 pounds of melamine/urea composites were made using 4 foot diameter pan agglomerators. Different composites were produced, at the melamine/urea ratios of 80/20,75/25, and 67/33.

Approximately 7% of the composites was provided by the urea added in the form of an aqueous binder solution, and the remaining urea was provided by powdered urea that was blended with the melamine powder prior to agglomeration.

In the foregoing examples, granular fertilizer products were prepared from commercially available, fine crystals of melamine. Similar granular fertilizer products can be prepared in substantially the same fashion from the hydrolysis products of melamine, i.e. ammeline, ammelide, and cyanuric acid, and from salts made from them and from melamine. Among the salts, the reaction product of nitric acid and melamine is a preferred material.

EXAMPLE XIII Corn trials using melamine-urea agglomerates; evaluation of different application techniques Test plots totaling 40 acres of sandy to light loams and silts were treated with different amounts of melamine agglomerates to provide several different levels of applied nitrogen per acre. Melamine-urea agglomerated composites were used, prepared according to Example I and having 67 parts melamine to 33 parts urea binder; 75 parts melamine to 25 parts urea binder; and 80 parts melamine to 20 parts urea binder.

The composites were successfully applied using different techniques: 1) spreading with a Barber spreader; 2) spreading with a Barber spreader and plowing into the ground; 3) aerial application by airplane; 4) shanking into the ground during planting.

The results observed are summarized in Table IV below.

TABLE IV Corn trials- effect of application method Number of Average Number Nitrogen Level Melamine/ Application Ears/100 of Ears (Ibs./acre Urea Technique Plants per Plant 140-150 75/25 (1) 155 1.55 140-150 75/25 (2) 147 1.47 140-150 75/25 (3) 155 1.55 150 80/20 (4) 153 1.53 0 (Control) - 132 1.32 400 UN-32 ** 129 1.29 400* * 145 1.45 * Standard Fertilizer Practice, several applications during the growing season.

** A total of 400 Ibs. N in the form of UN-32 applied in several applications during the growing season to simulate Standard Fertilizer Practice.

All of the test corn planting reported in these examples, where compared, were made within one week of each other if not essentially simultaneously.

Corn grown in plots fertilized by method (2), broadcasting, then plowing in, looked green and robustly healthy. Corn grown in plots fertilized by broadcasting only, methods (1) and (3), had yellow as well as green foliage, but was greener than corn fertilized by method (4), shanking in post-planting, which looked yellow.

In an effort to approximate yields which would not be available until later in the year, the ear counts in the same samples were retaken with the following adjustments: full ears recorded as 1, small ears as 1/2, and nubbins as 0. This count has been recorded in Table IV as effective ear counts.

TABLE V Corn trials - effects of application method Effective Average Effective Nitrogen Level Melamine/ Application Number of Number of Number of Ears (Ibs./acre) Urea Technique Ears/100'** Plants/l 00 ft. per Plant 140-150 75/25 (1) 109.5 109 1.0 140-150 75/25 (2) 118 126 0.94*** 140-150 75/25 (3) 120.5 115 1.05 150 80/20 (4) 60 134 0.45 0 (Control) - 40.5 95 0.43 400 UN-32 (1) 124.5 128 0.97 400* * 145.5 159 0.92 * Standard Fertilizer Practice, several applications during the growing season.

** Full ears recorded as 1, small ears as 1/2, and nubbins as 0.

Ear Ear sizes were also of interest: at 150 Ibs. N, applied as a 75/25 melamine/urea prill: 5-1/2 - 6 cm. diam.

SFP : 4-1/2 - 5 cm. diam.

In a further evaluation, corn plants were harvested and weighed, an ear count was taken, and ear weights were recorded, from two test areas. The first area was fertilized with 75/25 melamine/urea agglomerates by broadcasting the agglomerates, then discing them in. The second area was fertilized according to local standard fertilizer practice at 400 Ibs. N/acre. Standard fertilizer practice calls for the application of a total of 350 Ibs. to 400 Ibs. N per year per acre. This is accomplished by three separate steps. First, an early application is made of 200 Ibs. N/acre as an hydros ammonia. Second, 400 Ibs./acre of 16-20-0 is applied (based on monoammonium phosphate). Third, UN-32, comprising urea and ammonium nitrate, is applied through the irrigation sprinkler system. The results are summarized in Table V below. All samples taken were pre-dent.

TABLE VI Pre-dent evaluation of corn response Ratio of Ear Sample Selection Plants Ears Weight to Fertilization No. Technique Number Weight Number Weight Plant Weight Melamine/urea 75/25 1 Random 1/ 10 39 lbs. 20 18.5 lbs. 0.475 Agglomerates, at 2 Random 1/ 101 35.5 20 16 0.45 150 lbs.N/acre, 3 all taken 58 122 59 47.5 0.39 broadcast and from a 50 ft.

disced row 75/25 Agglomerates, 4 all taken 69 122 73 49.5 0.41 at 235 lbs.N/acre, from a 50 ft.

broadcast and disced row 75/25 Agglomerates, 5 all taken 64 134 67 47.5 0.35 at 150 lbs.N/acre, from a 50 ft.

flown on row Standard Fertilizer 1 Random 1/ 10 41 20 14 0.34 Practice, 350 to 400 2 Random 1/ 10 1 20 16.5 0.40 lbs.N/acre 3 all taken 79 142 77 47 0.33 from a 50 ft.

row 1/ In the random selection process, large plants have 2 ear each were taken from the ends of rows in open spots where there was a minimum of competition from other corn plants.

Claims (61)

1. A fertilizer product in granular form, the granules having strength, sizes and weights suitable for mechanical dispensing and application to the soil, said graules comprising: a particulate nitrogen source characterized by poor solubility in pH 7 water at 20"C., said source being selected from the group consisting of: melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts and mixtures thereof, and at least an effective amount by weight of the fertilizer granules of a binder for said nitrogen source particles that binds said nitrogen source particles into granular form.

2. The granular fertilizer of Claim 1 wherein the particulate nitrogen source is characterized by fine particle size not above 10 mesh.

3. The granular fertilizer product of Claim 1 wherein said granules comprise up to 80 parts by weight of said particulate nitrogen source.

4. The fertilizer product of Claim 1 wherein said granules comprise at least 20 parts by weight of said binder.

5. The granular fertilizer product of Claim 1 wherein said particulate nitrogen source is melamine and said binder is selected from the group consisting of urea, ammonium sulfate, potassium sulfate, ammonium nitrate, ammonium phosphate, potassium nitrate, potassium chloride, ammonium chloride, potassium dihydrogen phosphate, lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, starch, latex and mixtures thereof.

6. The granular fertilizer product of Claim 3 or Claim 4 wherein said particulate nitrogen source is melamine and said binder is selected from the group consisting of urea, ammonium sulfate, potassium sulfate, ammonium nitrate, ammonium phosphate, potassium nitrate, potassium chloride, ammonium chloride, potassium dihydrogen phosphate, lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, starch, latex and mixtures thereof.

7. The granular fertilizer product of Claim 1, wherein said granules comprise from 85 to 99 parts by weight of said particulate nitrogen source and from 1 to 15 parts by weight of a binder selected from the group consisting of lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, latex and mixtures thereof.

8. The granular fertilizer product of Claim 7, wherein said particulate nitrogen source is melamine.

9. The granular fertilizer product of Claim 1 or Claim 5 wherein said granule comprises from 60 to 80 parts by weight melamine and from 20 to 40 parts by weight binder.

10. The granular fertilizer product of Claim 1 of Claim 5 wherein said granule comprises from 67 to 80 parts by weight melamine and from 20 to 33 parts by weight binder.

11. The granular fertilizer product of Claim 1 or Claim 5 wherein said granule comprises from 60 to 80 parts by weight melamine and from 20 to 40 parts by weight urea.

12. The granular fertilizer product of Claim 1 or Claim wherein said granule comprises from 67 to 80 parts by weight melamine and from 20 to 33 parts by weight urea.

13. A fertilizer product in prill form prepared by: a) mixing fine powder particles of a particulate nitrogen source selected from the group consisting of: melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof, and an effective maount of a molten binder, and b) chilling drops of said mixture to form prills.

14. A fertilizer product in prill form as recited in Claim 13 wherein said binder is selected from the group consisting of urea, ammonium nitrate, potassium dihydrogen phosphate, and mixtures thereof.

15. Afertilizer product in prill form as recited in Claim 14 wherein said prill comprises from 10 to 67 parts by weight melamine.

16. Afertilizer product in prill form as recited in Claim 14 wherein said prill comprises from 35to 60 parts by weight urea.

17. The fertilizer product in prill form of Claim 16 wherein said prill comprises from 40 to 50 parts by weight urea.

18. A process of preparing a fertilizer product in granular form adapted for use as a source of nitrogen for fertilizing applications comprising: a) mixing a particulate nitrogen source selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts and mixtures thereof, and an effective amount of a binder suitable for binding said nitrogen source particles into granules having sizes and weights suitable for mechanical application.

b) contacting said mixture with a spray of water or an aqueous solution of binder, c) agglomerating the moistened mixture to form said agglomerates, and d) drying the agglomerates.

19. A process of preparing a fertilizer product as recited in Claim 18 wherein said binder is selected from the group consisting of urea, ammonium sulfate, potassium sulfate, ammonium nitrate, ammonium phosphate, potassium nitrate, potassium chloride, ammonium chloride, potassium dihydrogen phosphate, lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, starch, latex and mixtures thereof.

20. The process as recited in Claim 18, wherein said mixture comprises from 85 to 99 parts by weight of said particulate nitrogen source and from 1 to 15 parts by weight of a binder selected from the group consisting of lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, latex and mixtures thereof.

21. The process as recited in Claim 20, wherein said particulate nitrogen source is melamine.

22. The process as recited in Claim 18 wherein said mixture comprises from 60 to 80 parts by weight melamine and from 20 to 40 parts by weight binder.

23. The process as recited in Claim 19 wherein said mixture comprises from 67 to 80 parts by weight melamine and from 20 to 33 parts by weight binder.

24. The process of Claim 19 wherein said mixture comprises from 60 to 80 parts by weight melamine and from 20 to 40 parts by weight urea.

25. The process of Claim 19 wherein said mixture comprises from 67 to 80 parts by weight melamine and from 20 to 33 parts by weight urea.

26. The process of preparing a fertilizer product in prill form comprising: a) mixing fine powder particles of a particulate nitrogen source selected from the group consisting of: melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof, and an effective amount of a molten binder, and b) chilling drops of said mixture to form prills.

27. The process of Claim 26 wherein said binder is urea, ammonium nitrate, potassium dihydrogen phosphate or mixtures thereof.

28. The process of Claim 26 wherein said mixture comprises from 10 to 67 parts by weight melamine.

29. The process of Claim 26 wherein said mixture comprises from 35 to 60 parts by weight urea.

30. A process of fertilizing crops comprising dispensing to the soil a granular product comprising a particulate nitrogen source selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof, and an effective amount of a binder suitable for binding said nitrogen source particles into granules having sizes and weights suitable for mechanical application.

31. A process as recited in Claim 30 wherein said binder is selected from the group consisting of urea, ammonium sulfate, potassium sulfate, ammonium nitrate ammonium phosphate, potassium nitrate, potassium chloride, ammonium chloride, potassium dihydrogen phosphate, lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, starch, latex, and mixtures thereof.

32. A process as recited in Claim 31, wherein said granular product comprises from 85 to 99 parts by weight particulate nitrogen source and from 1 to 15 parts by weight of a binder selected from the group consisting of lignin sulfonate, urea formaldehyde resin, melamine formaldehyde resin, latex and mixtures thereof.

33. The process of Claim 32, wherein said particulate nitrogen source is melamine.

34. A process as recited in Claim 30 wherein said granular product comprises up to 80 parts by weight of said particulate nitrogen source and at least 20 parts by weight of said binder.

35. A process as recited in Claim 34 wherein said particulate nitrogen source is up to 80 parts by weight melamine and said binder is at least 20 parts by weight urea.

36. A process of fertilizing crops comprising dispensing to the soil a granular product having strength, size and weight suitable for mechanical dispensing and application, said granule being formed by: a) mixing a particulate nitrogen source selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their organic salts and inorganic salts, and mixtures thereof, and an effective amount of a binder that binds said nitrogen source particles into granules having sizes and weights suitable for mechanical dispensing and application, b) contacting said mixture with a spray of water or an aqueous solution of binder, c) agglomerating the moistened mixture to form said agglomerates, d) drying the agglomerates, and e) annealing the dried agglomerates.

37. A process as recited in Claim 36 wherein said binder is selected from the group consisting of urea, ammonium nitrate, potassium dihydrogen phosphate, and mixtures thereof.

38. A process of fertilizing crops as recited in Claim 36 wherein said particulate nitrogen source is melamine and said binder is urea.

39. A process of fertilizing crops comprising dispensing to the soil a fertilizer product in prill form preparing by: a) mixing fine powder particles of a particulate nitrogen source selected from the group consisting of: melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof, and an effective amount of a molten binder, and b) chilling drops of said mixture to form prills.

40. The process of Claim 39 wherein said binder is urea, ammonium nitrate, potassium dihydrogen phosphate or mixtures thereof.

41. The process of Claim 39 wherein said mixture comprises from 10 to 67 parts by weight melamine.

42. The process of Claim 39 wherein said mixture comprises from 35 to 60 parts by weight urea binder.

43. The process of Claim 39 wherein said mixture comprises from 40 to 50 parts by weight urea binder.

44. A process of furnishing a slow release source of fertilizer nitrogen to field soil as a nutrient source for a crop, comprising inserting and distributing in said soil in the root zone ih particulate form a fertilizer nitrogen source that is characterized by poor solubility in pH 7 water at 20"C., said source being selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof.

45. The process of Claim 44 comprising applying said slow release fertizlier nitrogen source in solid form on the surface of said field soil, then turning at least a portion of the soil over to insert and to distribute the fertilizer nitrogen source at the desired depth range throughout the soil.

46. The process of Claim 44 or 45 wherein said fertilizer nitrogen source is applied in the form of a slurry of solids suspended in an effective amount of a liquid vehicle for said nitrogen source particles that permits application of the particles to and their distribution in the soil.

47. The process of Claim 44 or 45 wherein said fertilizer nitrogen source consists essentially of melamine.

48. The process of Claim 45 wherein said slow release fertilizer nitrogen source is melamine and is applied in the form of a slurry of solids suspended in an effective amount of a liquid vehicle that permits application of the solid particles to and their distribution in the soil.

49. A granular agglomerate adapted for use as a source of nitrogen for fertilizing applications prepared by a process comprising the steps of: a) mixing a particulate nitrogen source selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts, and mixtures thereof, and an effective amount of a binder suitable for binding said nitrogen sources particles into granules having sizes and weights suitable for mechanical application, b) contacting said mixture with a spray of water or an aqueous solution of the binder, c) agglomermating the moistened mixture to form said agglomerates, d) drying the agglomerates, and e) annealing the dried agglomerates.

50. A granular agglomerate as recited in Claim 49 wherein said binder is selected from the group consisting of urea, ammonium nitrate, potassium dihydrogen phosphate and mixtures thereof.

51. The granular agglomerate of claim 49 wherein the binder is urea, said drying step is at a temperature less than 930c and said annealing step comprises heating at a temperature between 135"C and 149"C.

52. The granular agglomerate of Claim 49 wherein said particulate nitrogen source is melamine and said binder is urea.

53. The granular agglomerate of Claim 49 wherein said mixture comprises from 50 to 80 parts by weight melamine and from 20 to 50 parts by weight binder.

54. A process of preparing a fertilizer product in granular form adapted for use as a source of nitrogen for fertilizing applications comprising: a) mixing a particulate nitrogen source selected from the group consisting of melamine, ammeline, ammelide, cyanuric acid, mixtures thereof, their inorganic salts, their organic salts and mixtures thereof, and an effective amount of a binder suitable for binding said nitrogen source particles into granules having sizes and weights suitable for mechanical application, b) contacting said mixture with a spray of water or an aqueous solution of binder, c) agglomerating the moistened mixture to form said agglomerates, d) drying the agglomerates, and e) annealing the dried agglomerates.

55. The process of Claim 54 wherein said binder is urea, ammonium nitrate, potassium dihydrogen phosphate or mixtures thereof.

56. The process of Claim 54 wherein said binder is urea, said drying step is at 93"C and said annealing step is at a temperature between 135"C and 149"C.

57. The process of Claim 54 wherein said mixture comprises from 50 to 80 parts by weight melamine and from 20 to 50 parts by weight binder.

58. The process of Claim 57 wherein said binder is urea.

59. The process of fertilizing crops of Claim 30,36,39, or 44 wherein said crop is corn, potatoes, rice or wheat.

60. A fertilizer product substantially as hereinbefore described with reference to any of Examples I to XIII.

61. A process for preparing a fertilizer product substantially as hereinbefore described with reference to any of Examples I to XIII.