Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
1998-07-24
2002-10-15
Langel, Wayne A. (Department: 1754)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S029000, C071S030000, C071S064110
Reexamination Certificate
active
06464746
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to slow-release fertilizers, and more particularly to homogeneous granules of slow-release nitrogen and other fertilizer components. The invention also relates to a method of making the fertilizers.
BACKGROUND TO THE INVENTION
Among the qualities desired in commercial fertilizer products for the turf care industry are ease of application and longevity of activity. It is well known that slow-release fertilizer pellets provide both of those attributes, making slow-release granular fertilizers preferred by many turf care professionals.
Some of the most effective and desired slow-release fertilizer products are made from isobutylidene diurea (“IB”), and/or methylene ureas. For example, IsoTek
31®
, offered by Lebanon Seaboard Corporation, is one IB-based product that has enjoyed much success. This is because IB is only slowly decomposed by water (by chemical hydrolysis), products made with IB provide a desirably gradual nitrogen availability accompanied by a lesser nitrogen loss and a reduced propensity to injure fertilized plants due to salt concentration effects.
Unfortunately however, several problems are associated with isobutylidene diurea and other slow-release fertilizers when provided in blended granular pellet form. For example, prior art granular IB-based fertilizers have heretofore been resistant to breakdown by moisture, so that granules applied to turf remains visible long after application, and are frequently picked up and lost with clippings during mowing. Further, in the standard ammoniation process it is difficult to produce a homogeneous product containing more than 20% nitrogen, even when compounded with additional nitrogen sources. Additionally, the standard process produces products having a nitrogen activity index of only about 35%, meaning 65% or more of the WIN is not available as plant nutrient in a timely fashion.
A need therefore exists for a fertilizer particle which will deliver high doses of slow-release nitrogen, and/or a combination of slow-release nitrogen technologies, in a pellet with improved dispersibility. The present invention addresses that need.
SUMMARY OF THE INVENTION
Briefly describing one aspect of the present invention, there is provided a process for making homogeneous granules of fertilizer. The preferred process combines three things: (1) a dry fertilizer mix that includes a source of slow-release nitrogen such as isobutylidene diurea and/or methylene ureas; (2) a urea-formaldehyde resin binder; and (3) a moisturizer such as water (steam or liquid), liquid urea, etc. The three items may be combined in any order.
One object of the present invention is to provide homogeneous granules of fertilizer to deliver high levels of efficient slow-release nitrogen in particles that readily disperse when contacted by moisture.
Further objects and advantages of the present invention will be apparent from the following description.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to preferred embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the preferred embodiments, and such further applications of the principles of the invention as described herein being contemplated as would normally occur to one skilled in the art to which the invention pertains.
As briefly described above, the present invention provides a process for making homogeneous granules of fertilizer to deliver high levels of slow-release nitrogen in particles that readily disperse when contacted by moisture. The preferred process combines a dry fertilizer mix, clay, a urea-formaldehyde resin binder, and a moisturizer. Most preferably, the dry fertilizer is first mixed with dry urea-formaldehyde resin, and the combined mixture is then granulated by mixing with dilute liquid urea. Water (provided as liquid or steam) may be added as necessary to complete the granulation. Drying and screening for size typically concludes the process.
Describing first the dry fertilizer mix, the inventive fertilizers described herein feature high levels of slow-release nitrogen in an easily dispersed formulation. Preferably, isobutylidene diurea (“IB”) is used as one source of slow-release nitrogen because it is effective and familiar to the turf care industry. Even more preferably, IB is used in combination with another slow-release source of nitrogen such as Meth-Ex 40® methylene urea to provide slow-release nitrogen to the fertilizer. IB and a high activity index methylene urea such as Meth-Ex 40® are used in the most preferred embodiments.
In alternative embodiments other nitrogen-source materials are granulated according to the present invention. For example, in addition to IB and methylene urea, ammonium nitrate, ammonium sulfate (“AMS”), etc., may be used alone or in combination with IB and/or methylene urea.
In addition to the slow-release nitrogen, the dry fertilizer mix also preferably contains a source of phosphorus and a source of potassium. The source of potassium may be potash (KC
1
) or its sulfates, etc., all of which are available commercially. In the most preferred embodiments sulfate of potash (“SOP”) and/or sulfate of potash-magnesia (“SPM”) are used. The source of phosphorus may be monoammonium phosphate (“MAP”), diammonium phosphate (“DAP”), triple super phosphate (“TSP”), etc., all of which are generally available from commercial sources.
The amounts of nitrogen, phosphorus, and potassium included in the dry fertilizer mix may range from 0% to about 60% for each component. Most preferably, between about 0-60% slow-release nitrogen, 0-60% of a potassium source, and 0-60% of a phosphorus source are included in the dry fertilizer mix.
In addition to nitrogen, phosphorus, and potassium, the dry fertilizer also preferably includes other fertilizer components and/or nutrients such as iron, manganese, calcium, micronutrients, etc. The forms and source of these components are known to persons skilled in the art, and the appropriate amounts may be selected without undue experimentation.
Additionally, particles of clay, such as attapulgite or bentonite clay, are also preferably included in the blend. The clay facilitates granulation, and is preferably included at levels of about 25-150 pounds per ton. Most preferably, 25 to 75 lbs of attapulgite clay per ton of dry ingredients are used.
In the most preferred embodiments a dry fertilizer/clay mixture is prepared which contains 5-50% IB, 2-20% Meth-Ex 40®, 5-50% potash, 5-50% monoammonium phosphate, 0.1-5% iron, 2-10% clay, and 2-20% urea.
Describing now the urea-formaldehyde resin used in the present invention, the preferred resin is a dry powder with a long storage life (at least 90 days) under normal storage conditions (dry, at temperatures between 15° C. and 30° C.). The resin preferably contains between about 10% and about 40% nitrogen, and most preferably contains about 30% N. Of the nitrogen contained in the resin, preferably less than about 10% is water insoluble nitrogen (WIN), and preferably less than about 1% is hot water insoluble nitrogen (HWIN). In the most preferred embodiments the resin contains less than 5% WIN, and less than about 0.1% HWIN.
It is also important that the urea-formaldehyde resin not be a resin that builds unacceptable levels of WIN or HWIN when used as a binder in nitrogen-containing fertilizers. The preferred urea-formaldehyde resin builds only modest amounts of WIN and HWIN, so that the WIN in the granulated product is less than about 7%, and the HWIN in the granulated product is less than about 2.8%. Most preferably, WIN levels of less than 5%, and HWIN levels of less than 2% are obtained in the granulated product. Resins such as GP 3865 resin from Georgia-Pacific Resins, Inc. are capable of providing that performance.
In the most preferred embodiments the resin has a urea:formal
Derr Elmer A.
Neyman Gary B.
Langel Wayne A.
Lebanon Chemical Corporation
Woodard Emhardt Naughton Moriarty & McNett
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