CA1188124A - Fertilizer compositions, processes of making them, and processes of using them - Google Patents

Abstract

ABSTRACT
, This invéntion relates to a fertilizer product in granular form, to processes for making and using it. The granules have strength, sizes and weighcs suitablc for mechanlcal dispensing and appllcatlon to the soil. These granules combine a partlculaee nitrogen source such as melaraine with a binder such as urea.

Description

YERTILIZER COMPOS TION~S, PROCF.SSES 0~' ~AKING THEM
A~D PROCFSSES O_ IJ NG rHEM
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This invention relates to a ne~J fer~ilizer product in composite granular form9 to a process for maklng it, and eo a process for using it. More particularly 9 the inven~ion relates to a granular fertilizer produc~ in which the gran-lles have strength, sizes 9 and ~eigh~s suitable Eor 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 eogether with a binder such as 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 co 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, ammelideg and cyanuric acid9 have been considered as potential sources of nitrogen for incorporation in fertilizer com?ositions or for uti~ization as nitrogen sources per se. Melamine has a nitrogen content of 66.5%. 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 ecpensive than urea. Moreover, commercially produced melamine is available only as a fine crystalline powder. It is manufactured in the fol~ of very fine crystaLs because small size particles are required for the present commerc:ial end markets for melamine, such as, for ecample, the ,,~9 procluc~ion of melamine-formaldehyde resins and the productlon of flre retardant paints.
A typical screen analysis for one coTm~ercially 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 .~esh 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 1PSS desirable. In the fire retardant paint market, the melamine crystals are dispersed in the paint, where the currently used fine particle sizes produce a smooeher texture in che 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 apylied to the surface of the ground, would be blown away by even mild winds. If applied by alr, 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 ~ 4~ J-~

co~mercially available melamine solids would ~lake any large scale agricultural application impractical.
SUMMARY OF TaE INVENTION
_.
In one of its aspects9 this invention resides in a fertilizer product in granule form. The fertilizer granules have streng~h7 sizes, and weights thac are suitable for dlspensing mechanically for application to and into the soil. The preferred siæe range is from about 1 millimeter to abou~ 10 millimeters, and che most yreferred size range is from 3 mm. ~o 5 r~m.
These ferr~lizer granules comprise a partlculate nitrogen source and a binder~ The nitrogen source is oharacterized by fine particle sizes not above about 10 mesh, by poor solubility in pH 7 wa~er at 20C, 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 chereof, their inorganic salts, their organic salts and mixtures thereof.
The binder is present in an amount at least sufficient to 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 urea9 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 thereo.

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In a preferred embodiment the granules comprise up to 80 parts by weight of the particulate nitrogen source and at leas~ 20 parts by weight binder.
In a more preferred embodiment the granules comprise from 60 ~o 80 parts by weight melamine and from 20 to 40 parts by weight urea. In another preferred embodiment the granules comprise from 67 to ~0 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.
I0 In another aspect this in~ention resides in a granule prepared by a process having an annealing step to provide enhanced strength to the granule and adapting chem for use as a source of nitrogen for fertilizing applications. This process involves mixing a particulate nitrogen source selected from the group of maeerials 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 agglomerated, dried and annealed. In a preferred embodiment the process requires a drying temperature of less than 93C and an annealing tempera~ure between 135C and 149C. 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 prill is prepared by mixing an effective amount of a molten binder selected from the group of binder materials listed above wlth fine powder particles of a particulate nitrogen source selected from the group listed above. Drops of this mixture are then chllled to form prills. In a prefer.ed embodiment this prill comprises from 40 to 65 parts by weight melamine as the particulate nitrogen source and from 35 to 60 parts by welght urea binder. In another preferred embodiment this prill comprises 50 to 60 parts by weight melamine and 40 to 50 parts by weight urea.

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In ano~her ernbodiment this invention in~olves a process ot preparing a fertiliz2r product in granular form adapted for ~se 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 wieh a spray of water or an aqueous solution of the binder, agglomera~ing the mois~ened mixture to form agglomerates and drying the agglomerates. The agglomerates are screened to produce product agglomerates having sizes in the raage of 1 mlllimeter to 10 millimeters9 preferably. Over-sized particles can be crushed to size 9 and fines can be recycled.
In anothPr preferred embodiment the process requires mi~ing from 50 to 80 parts by weight melamine with from 50 ~o 20 parts by weight urea binder. In a most preferred embodimene this process invo~ves 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 in~rolves 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 93C and annealing the dried agglomerates at a temperature between 135C and 149C. In another preferred embodiment this process comprises mixing from 50 to 30 parts by weight melamine and 50 to ~0 parts by weight urea.
As a rule, crush strengths of 1000 grams or greater are attained where the annealing step of heating to 135UC to 149C is carried out on the granules made from melamine and urea.
In another aspect this invention is a process of fer-tilizi.ng crops comprising dispensing to the soil a gr~nular product comprising a particulate nitrogen sourc~ 3elected from the group listed above and an effective amount of a binder selected from the 'f-~

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 weighe of the particulate nitrogen source and at lease 20 parts by weigh~ binder. In a most preferred embodiment this process involves dispensing a granular produc~
comprising up to 80 parts by weight melamine and ae least 20 parts by weight urea.
In another aspect t:his inveation is a process of fer-tilizing crops which involvPs dispensing to the soil a granular product having strength, size and weight suieable for mechanical dlspensing and application formed by ~iXillg an effectlve amount of a binder selected from the gro~p 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 binderJ agglomerating ~he moistened mixture to for~
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 ~his 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 fer-tilizer nitrogen for an entire growing season. A primary ad-vantage 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 fur-nishing a slow release source of fereilizer ni~rogen to field soil as a nutrient source for a crop by inserting and distributing in the soil in ehe root zone in partLculate fo~l a fertilizer nitrogen bJ ~

so71rce that is characterized by poor solubility in pH 7 water at 20C. This slow release nitrogen source may be melflmine, ammeline, anmelide, cyanurlc acid, their organic or inorganlc salts or mixtures thereof. After app:Lying the solid form of the nitrogen so~rce on the surface of the soil a portion of the soil is turned over to insert and distribute the fertilizer ae the desired depth range throughout the soil.
In another aspect this invention ls 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 ~he nierogen sourcs that permits applica_ion of the slow release fertilizer part:Lcles to and their d-Lstribution in the so il .
DEFINITIONS:
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The term "poorly water soluble" refers to materials that dissolve in water a~ 20C, pH7, to the sxtent of 5 grams per 100 grams, or less; that is, materials ehat fo~ solu~ions of 5~ or less concentration. The ter~ "poor solubility" in pH 7 water at 20C has the same meaning.
The term "readily water soluble" refers to materials that dissolve in water at 20C, p~ 7, to the extent of 20 grams per 100 ~rams or more, that i8, materials that form solutions of 20~ or greater concentration.
3ased on available information, the solubi].ities in water at 20C, pH 7, for several materials useful in connection with this invention, in grams per 100 grams are:
Table I
Solubility Data Material ~1O0Q
melamine 0.50 ammellne 0.008 ammelide less than 0.008 cyanuric acid 0.27 me]amine nitrate 0.85 ammonium nitrate 192 anmonium sulfate 75.4 ~ 9~

diammonium phosphate 13J ~at 15~
potassium ac~d sulfate 51 po~assium sulfate L1~1 urea 11').3 (at 25C) Fertilizer products in accordance with ~he prasent in~
ven~ion are in granular form, with sizes in the range from about 1 mm. to lG mm., preferably 3 mm. to 5 mm. They are made up to have good drillability, a desirable apparent specific gravity, and eo be substantially free from dusting. The granules are also made to be suitable Eor mecha~ical dispensing and application to and into the soil using modern tools.
Granular fer~ilizer products made in accordance with pre~
ferred embodiments of the inventlon may be in the form of agglomer-ates or prills. The agglomerates may be made by any conventional technique for agglo~erating fertilizer products, ucilizing the poorly or sliss,htly soluble fertilizer nitrogen sources of the present invention, followed by an annealing treatmen~ to provide sufficient crush strength. Thus, the poorly or slightly soluble nitrogen source in an agglomerate is selected from the g,roup consisting of melamine, ammeline, ammelide, cyanuric acid 9 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, bisulfa~e9 and sulfite, and, as well, the acetate, cyanura~e, chloroacetate, for~ate, benzoate, fumarate, lactate, maleate, and phthalate, and mi~tures thereof.
These materials are characterized by poor or slight solubility in pH 7 water at 20C, and by slow conversion in the soil to a form in 3 which the nitrogen is useful to plant liEe growing in ~he soil.
These nitrogen source materials, as ordinarily available commercially or as prepared, are in the form of ~ery fine partic]es. In the case of melamine, for example, the commercially available product typically has crystalllrle yar~icles that are smaller in si~e than 10 mash7 IJ.S. Standard Sleve size, and generally, mostly smaller than 40 meshO These very fine, powdery nitrogen source materials are agglomerated through the use of a binder~ Generally the binder forms at least 1~ by weigh~ uf the powdery particles, preferably ae 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 0 with the soil so that lt and any residue thereol is either inert, biodegradable, soil-conditioning, or has some plant nutrien~ 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 ehe range from 3 mm.
to 4 mm., the results being averaged. Preferably, however, the crush strength i~ at least 680 grams~ and more preferably, 908 grams or higher. A c~lsh strength of about 454 grams is comparabls to conventional, commercial prilled urea and is adequate strength for use in most forms of commercial application, including broad-cast devices, spreaders, planter shank applicators, and for dis pensing 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 for~aldehyde resins, and latices of synthetic polymeric materials. Those binders are most preferred that have plant nutrient value, as do urea, urea-~ormaldehy*e and melamine-formaldehyde resins.
In one preferred agglomeration technique, the melamine powder 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 J A ~

eithe~ goes into solution or becomes moistened and tacky, and in either state, coats the powdery melamine par~icles sufficLently to cause agglomeration to occur. The agglomerates are drled and cooLed, to form hard composltes having sizes primarily in the rante from about l mm. to about 10 mm., and preferably 3 mm. to 5 mm.
These composites have good crush strength and are substantiall~J
free from duseing.
Any of the conventional agglomerating techniques can be used. Thus, all of the bindler can be applied in solution. r~hen ~he binder is a material such as llgnin sulfonate9 urea-formaldehyde resin, or melamine-formaldehyde resirl, 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, bu~ such a material, while having excellent characteris-tics as a binder, has no nutrient value to contribute and is there-fore less desirable. The same considerations apply to synthetic polymex latices.
The fertili~er particles of the invention may also be made in the form of prills. In che 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 or its nitrogen content and ready solubility in r~ater, and also because melamine is some~hat soLuble in molten urea, oeher ma~erial such as sulfur could also be used, and-mixtures of materials could be used. In forming urea-bound prills7 it is preferred that the prill product contain at least 33% by weight of urPa. 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 ~hat the melamine content may be in the range from 10% to 67% by weight of the prills. Preferably, the urea content is Erom 35% to 60% by weight of ~he prillsg and more preferahly, from 40~ to S0~ by weight .
While preferred granular products are produced by agglomeraeion and prilling, satlsfactory products can be produced bv other techniques~ including e~truding techniques, pressing and granulating, and bricquetting. For example, melamine powder, or a powdered melamine salt, or the like, can be combined with a urea formaldehyde resin in powder form to form a mi~ture. The mixture can be pressed at an elevated temperature to cure the resin, and the resulting product can be granula~ed to form particles o~ the desired size, or the pressed, cured mass can be converced to flake form. Screening and recycling can be used as necessary to develop granules of the desired siæes.
Readily soluble binder~ such as urea and salts such as ammonium nitrate permit rapid disintegration o~ 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 che 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 fer-tilizer granules of sufficient size, strengeh, 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 rap~dly and releases the fine particles of the poor]y soluble nitrogen source into ~he soil, for slow dissolution or biodegradation.
When an agglomerate is prepared from powdered melamine and a readily water soluble binder such as urea, preferred pro-portions in ttle dried granular product obta:ined are from 60% 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 frorn 33%
to 20% by weight of urea. The most preferred granule comprises about 67 parts by weight melamine and abou~; 33 parts by weight urea.
~ hen an agglomerate is produced USillg 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 3~terials such as a phenolic resin, or a synthetic polymer in the form of a latex, a very slow release of nitrogen from the melam:Lne particles (or particles of other poorly soluble nitrogen source) is obtained.
For the production of an agglomerate permitting a single application per growing season, fast release ~itrogen fertilizer materials, generally an ammonium salt or urea, are advantageously u~sed 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, a~monium 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 agglomérate, and preferably i5 from 20~ eo 33% by weight of the a~glomerate.
In addition, other ~aterials may be incorporated in a granular fertilizer product prepared in accordance with the in-- vention. Such macerials 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 practiceO
Because less of the active material is actually needed~ it may be desirable, to facilitate application, in some cases, to incorporate -12~

3 ~

an inert filler. Any of the conventional ~iller ~aterials may be employed, such as~ for example, gypsum, clay~ sand~ ground sea shells, ground dolomite, and ground Limestone.
~ no~her importanc advantage of the use of granular fertilizer products in accorclance wlth ~he present invention is ~hat, because of the slow release characteriscics~ it i5 possible to employ only a single application per growing season. In addition, after the initial application, in the case of ~elamine based fertilizer products in particular, the release of nitrogen values into the soil appears to continue over ewo 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 ~nexpected and surprising finding that furnishing a majority or all of the nltrogen fertili2er requirements by a nitrogen fertllizer source in accordance with the present invention apparently leads to a more effective production of agricultural productive units per unit weight of nitrogen applied, and per unit of growing area. An agricultural productlve unit is a seed, fruit, flower, vegetable, vegetable fiber, tuber, or the like. In addition, ehe practice of the invention apparently leads to overall yields of plant uni~s comparable to those obtained when following conventional, standard fertilizer practice, with its requirement for the use of much higher nitrogen fertilizer application levels.
In broad terms, this invention may be considered, in one example, as a process for increasing the effec~iveness of standard readily soluble, fast release nitrogenous fertilizers in generating productlve 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 advancageously with frolll about 50~ to 90% of poorly soluhle ma~erials recited abo~e.
The agricultural crops e~pec~ed to respond to treatment in accordance with the lnvention include subs~antially all crops, but particularly those where fruit is the harvested unlt ra~her than the entire plant. Such crops include food grains, feed grains, legumes, fibers9 roo~ crops, cltrus, ~ubers, oil bear~ng units including nuts, fruits and seeds~ commercial vegetables, commercial melons, tree fruit:s, vine fruits, bush fruits and flowers. Exemplary food grains include wheat3 rye, and rice. Feed grain crops include field corn9 oats, barley and sorghum. Legumes include soybeans, peanues, beans and peas. Fiber crops include cotton, hemp and ~ute. Root crops include sweec potatoes and sugar beets. Citrus crops include oranges, tangerines, grapefrult, lemons and limes. Tuber crops include potatoes. Oil crops include fla~, saEflower, sunflower, and castor bean. Co~mercial 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 raspbarries and blueberries. Tree nut crops include almonds, filberts, pecans and walnuts. These are intended to be e~emplary only.
The invention wiLl be better understood by reference to the following examples. Throughout this application and in these examples, all references to parts and percentages are by weight, and all references to temperatures are in degrees Celsius, unless expressly stated otherwise.
~ 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, Loui.siana. It was a fine white crystalline powder having a screen analysis substantially as reported above for commercially availab:Le 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 ollt in some of ~he foLlow:ing examples, c1~sh strengths oE 454 grams or greater are preferred. More preferably crush strengths of 1362 grams or more are developed7 to facilitate application. Also~ the bulk density or the granules should be 40 lbs./ft3 or more. The preferred combination of bulk density, crush strength9 and particle size m~kes for flexibility in and ease of application. Usually crush strengths of 1000 grams or greater are attained when the annealing step of heating to 135~C to 149C is carried out on the melamine urea granules.
EX~MPLÆ I

Three batches of composi~e granules were made up, each containing different amounts of urea and melamine9 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 po~der to form a homo-geneous 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 7Z urea to the dried agglo merate. The remainder of the urea content was derived from the urea powder in the urea-melamine powder mixture, Annealed Melamine Granules .
A batch or granules was prepared using 67 parts of melamine crystals and 33 parts urea. The granules were made on an 18 inch disc pelletizer. The urea was first ground, then blended with the melamine to form a homogeneous mixture. This mixture was fed to the pelletizer and sprayed with water. The granules were dried at 200F. (94C) for about 20 minutes and then were subjected to a further step of heating in a laboratory o~en to 149C Eor 3 ~ r minutes. After cooling~ the crush streng~h and rate of breaking apart in water were measured. These values are reporeed in Tab:Le I
below.
Table I
Crush S~rength Time to Dlsintegration Example 1 600 immediate Dried Granules E~ample II 2400 20 to 30 seconds Annealed Granules This Example illust:rates the relationship between time and temperature in the annea]ing step.
E ~
Annealed Melamine Granules Melamine granules prepared according to E~ample II were heated in separa~e batches at 104C, 149C, and 17~C for varylng times. A standard labora~ory oven was used. After cooling, the crush strength was measured. The results appear in Table II. The maximum crush strength at 17ZC appears at 6 minutes heating. The maximum crush strength appears at 149C aL 11 minutes heating.
Shorter drying times and annealing times will be possible in pro-duction when forced air dryers or ovens wiil be used in place of the laboratory oven used in these examples.
Table II
Oven Temperature ~inutes Crush Strength C Heating 104C ~0 560 14~30 14 1~45 ~0 145 17~C 4 763 Example IV

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 consisLed only of water. The resulting composites eontained 80% melamine and 20%
urea, and after screening co 3-4 mm. 5 were found to h~ve a crush strength of 953 g. using the same testing technique as in Example I~
Example V

Granular agglomerates wer~ prepared with a 16 inch pan agglomerator using melamine with several different binders. In each case, the binder, in llquid form, was sprayed on the melamine.
After drying, crush strength was determined as in Example I~ The results are reported in Table III, belowO
TABLE III
Crush Strengths Observed Melamine_A~glomerated with Different Binders Crush Strength, grams of 3-4 mm.
Binder A~Lo______s Calcium lignln sulfonatel 908 UCAR 368 late~ 681 ~elamine-formaldehyde resin1 1544 Urea formaldehyde resin 1 454 Diammonium phosphate (DAP) 91 Ammonium nitrate 150 1Applied at 30~-50% solids. The dried agglomerates were about 5% binder.
~Substantially sa~uraeed solutions used. The dried agglo-merates were approximately 93~ melamine, 7~ salt.
E~ample VI
. ~ 1 with other Fertili~er Materials Melamina, ammonium phosphate, and potassium chloride were blended to~ether in a 70:15:15 weight ra~io. 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-h mm. size range, and a bindar content of 3%.
Example VII
~ Solidified U~ea Binder Z0 Melamine and urea powder were blended in a 63~37 ratio, The blend was heated until a molten slurry was obtained. The slurry ~as then poured onto a cooling slab so as to form both a thill film and a thick film. After cooling the thin film was broken into flakes.
The thick film, of about 4 l~m. thickness~ was broken into granules. The crush strength of the 3-4 mm. granules was ex-ceptionally high, at 2500 grams.

A Pressed ~lelamlne-Urea Com~osite A melamine-urea blend was for~ed as iII Example VII. This blend was then placed in a heated platen press at about 500 psi for 5 minu~es, at 138C. The resulcing 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~
V~ranu:Les of the composite had a crush streilg~h of 2S00 grams.
Example IX
Melamine-lJrea 60/40 Prilis 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 135C. Holes were then p~mched in the can bot~om~ allow-ing the slurry to drip. A plastic sheet spread on the ground eaught the falling prills as they dropped from the fourth story level.
The largest prills did not cool before landing and smashed. Howe~er, the smaller prills cooled and solidified, and were collected for strength testing. Fairly good srrength results were achieved, although not measured. Crush strength would be expected to be similar to the granules of E~ample VII.
Example X
Melamine Agglomerated w th a Latex Binder 5% Union Carbide UCAR 368 Latex, 15% water, and 80%
melamine were combined into a flowable slurrv. 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.
~e~
Pressed Com~osite of ~felamine and Ure-Formaldeh~de 25 grams of urea, 70 grams melamine, and L5 ml. of 27~
formaldehyde solution were mixed together and pressed at 149C and 500 psi to form a thick sheet. Crush strength of 3-4 rnm. granules was 680 grams.
Examele XII
Melamine-[Jrea Agglomeraces for Fie d _ ials For field trials, 16,000 pounds of melarrline/urea com-_19_ posites were made USillg 4 foot diameter pan agglomera~ors.
Different composites were produced9 at the melcLmine/urea ratios of 80i20, 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 provLded by powdered urea that was blended with the ~elamine powder prior to agglomeration In the foregoing examples9 granular fertilizer products were prepared from commercially available~ fine crystals of melamine. Simllar gxanular Eertilizer products can be prepared in substantially the same fashion from the hydrolysis produces of melamine, i.e. amrleline, a~melide, and cyanuric acid1 and from salts made from them and from melamine. Among the salts, the reaction product of nitric acid and melamine is a preferred ma~erial.
Exampie XIII
Corn~0[1 LL~aL~cL~

Application Techniques Test plots totaling 40 acres of sandy to light loams and silts were treated with d~fferent amounts of ~lelamine agglomerates to provide several different levels of applied nitrogen per acre.
Melamine-urea agglomeraeed composites were used, prepared according ~o Example I and having 67 parts melamine to 33 parts urea binder;
75 parts melamine to 25 parts urea binder; and 80 parts melamine co 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 su~mari~ed in Table IV below.
Table_IV
Corn Trials Effect of Applica_i D ~le~llod T!Tumber of Average Number Nitrogen Level Melamine/ Application Ears/100 of Ears (lbs./acre Urea l~ _ P1ants ~er Plant 1~0 150 75/25 (1) 155 1.S5 1~10-~50 75/25 (2) 147 1.47 140-150 75/25 (3) ]5~ 1.55 150 80/20 ~4) 153 1.53 0 (Control) - 132 1.32 400 UN-32 ** 129 1.29 400* ~ 1~5 1.45 *Standard Fertilizer Practice, several applications during the growing season.
**A total of 400 lbs. N in the form of UN-32 applied in several applications during the growlng season to simulate Standard Fertiliæer Practice.
All of the test corn plantings repor~ed in these examples, where compared, were made within one weak of each oeher if no~ essentially simultaneously.
Corn grown in plots fertilized by method (2), broad-casting, thea plowing in, looked green and robustly heal~hy. Corn grown in plots fertilized by broadcasting only, methods (1) and (3) 9 had yellow as well as green foliage, but was greener than corn fertilized by me~hod (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 councs 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.

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N/acre as anhydrous ammonia. Second, 400 lbs./acre of 16-20-0 ls applied ~based on monoammonium phosphate) Third, UN-32, com-prising urea and ammonium nitrate, is applled throl1gh the irri-gation sprinkler system. The results are su~marized in Table V
below. All samples taken were pre-dent~

Other aspects of the invention are the subject of applications 411,552 and 411,595 concurrently herewith.

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Claims (20)

The embodiments of the invention in which an exclusive property of privilege is claimed, are defined as follows:

1. A granular fertilizer product that in the soil is a source of nitrogen fertilizer values, the granules being suitable for mechanical dispensing for application to and into the soil, said granules consisting of a mixture comprising:
particles of melamine having individual particle sizes not above 400 micrometers in largest dimension, in in amount from 10%
to 67% by weight of said granules, and an effective amount by weight of the granules, of a urea binder that binds said particles in a form which is granular, the amount of said urea binder being from 33% to 90% by weight of said granules, said granules having been formed ox heating said mixture above the melting point of urea, then cooling in solidify the urea, said urea binder, after distribution of the granules in the soil, permitting the action of water and microorganisms on said particles, said granules being suitable in granule strength and weight for mechanical dispensing and for application to or into the soil, the average crush strength of a sample of said granules, selected to huge sizes of 3 mm. to 4 mm., being at least one pound per granule .

2. The granular fertilizer product of claim 1 wherein the melamine comprises from 40% to 65% by weight of the product, and the ureu binder comprises from 35% to 60% by weight of said granules.

._

3 . The granular fertilizer product of claim 1, wherein said urea binder is solidified from the molten state

4. A granular fertilize product that in the soil is a source of nitrogen fertilizer values, the granules being suitable for mechanical dispensing for application to and into the soil, said grarlules consisting of a mixture comprising:
particles of a material selected from the group consisting of the mineral acid salts of melamine, melamine, and mixtures thereof, said particles having individual particle sizes not above 900 micrometers in largest dimension, in an amount from 10% to 67% by weight of said granules, and an effective amount by weight of the granules, of a binder that binds said particles in a form which is granular, the amount of said binder being from 33% to 90% by weight of said granules, said binder having been solidified from the molten state, said binder being selected from the group consisting of ammonium and potassium salts of mineral acids and urea, said binder, after distribution of the granules in the soil, being capable of undergoing rapid disintegration with release of said particles thus permitting the action of water and microrganisms on said particles, said granules being suitable in granule strength and weight for mechanical dispensing and for application to or into the soil, the average crush strength of a sample of said grarlules, selected to have sizes of 3 mm. lo 4 mm., being at least one pound per granule.

5. The granular fertilizer product of claim 4, wherein said particles are melamine particles and the melamine comprises from 40% to 65% by weight of said granules, and said binder is urea and comprises from 35% to 60% by weight of said granules .

6. The product of claim 4, wherein said mixture comprises at least one salt that furnishes at least one N, P, or K
value.

7. A granular fertilizer product that in the soil is a source of nitrogen fertilizer values, said granules being suitable for mechanical dispensing for application to and into the soil, said granules consisting of a mixture comprising:
particles of a material selected from the group consisting of the mineral acid salts of melamine, melamine and mixtures thereof, said particles having individual particle sizes not above 400 micrometers in largest dimension, in an amount from 20% to 80% by weight of said granules, and an effective amount by weight of the granules, of a readily water soluble binder that binds said particles in a form which is granular, said binder being selected from the group consisting of:
ammonium sulphate, potassium sulphate, ammonium nitrate, ammonium phosphate, potassium nitrate, potassium chloride;
ammonium chloride, potassium dihydrogen phosphate, and mixtures thereof, and urea, said granules having been formed by agglomerating said mixture to cause the binder to bind said particles into granular form, said binder, after distribution of the glanules in the soil, being capable of undergoing rapid disintegration with release of said particles, thus permitting the action of water and microorganisms on said particles, said granules being suitable in granule strength and weight for mechanical dispensing and for application to and into the soil, the average crush strength of a sample of said granules, selected to have sizes of 3 mm. to 4 mm., being at least one pound per granule.

8. The granular fertilizer product of claim 7 wherein said mixture consist of particles of melamine in an amount from 60% to 85% by weight of said granules and wherein said binder is present in an amount from 15% to 40% by weight of said granules.

9 The granular fertilizer product of claim 8 wherein said mixture consists of particles of melamine in an amount from 67% to 80% by weight of said granules and wherein said binder is present in an amount from 20% to 33% by weight of said granules.

10. The granular fertilizer product of claim 7 wherein the said mixture consists of particles of melamine and wherein said binder comprises urea.

11 The product of claim 7 wherein said mixture comprises at least one salt that furnishes N P or K value.

12. The granular fertilizer product of claim 7 said granules consisting of a mixture of:
particles of melamine having individual particle sizes not above 400 micrometers in largest dimension in an amount from 60%
to 85% by weight of said granules and a urea binder in the amount of from 15% to 40% by weight of said granules .

13. The granular fertilizer product of claim 12 wherein the said mixture consists of particles of melamine in an are from 67% to 80% by weight of said granules and wherein The amount of said urea binder is from 20% to 33% by weight of said granules.

14.. The granular fertilizer product of claim 7, wherein said binder comprises ammonium nitrate, and wherein said binder is present in an amount from 15% to 40% by weight of said granules.

15. The granular fertilizer product of claim 7, wherein said binder comprises a mixture of an ammonium phosphate and potassium chloride, and wherein said binder is present in an amount from 15% to 40% by weight of said granules.

16. A granular fertilizer product that in the soil is a source of nitrogen fertilizer values, said granules being suitable for mechanical dispensing for application to and into the soil, said granules consisting of a mîxture of:
particles of a material selected from the group consisting of the mineral acid salts of melamine, melamine, and mixtures thPreoff said particles having individual particle sizes not above 400 micrometers in largest dimension, and an effective amount by weight of the granules, of an insoluble resin binder that binds said particles in a form which is granular, the amount of said binder being at least 1% by weight of said granules, said binder, after distribution of the granules in the soil, permitting the action of water and microorganisms on said particles, said granules beîng suitable in granule strength and weight for mechanical dispensing and for application to and into the soil, the average crush strength of a sample of said granules, selected to have sizes of 3 mm. to 4 mm., being at least one pound per granule .

17. The granular fertilizer product of claim 16, wherein the amount of said binder is at least 2% by weight of the granules, and said granules have been formed by agglomerating said mixture and causing said binder to bind said particles in granular form.

18. The granular fertilizer product of claim 17, wherein at least a part of the resin binder is applied as an aqueous spray to said particles and comprises a solution of a lignin sulonate salt .

19. The granular fertilizer product of claim 17, wherein the amount of said binder is at least 5% by weight of said granules and is selected from the group consisting of a urea-formaldehyde resin, a melamine-formaldehyde resin, and a lignin sulgonate salt.

20. The granular fertilizer product of claim 17, wherein said binder comprises at least 5% by weight of said granules and is applied as a latex.