FIG. 3 depicts an embodiment of a process by which a blended fertilizer is produced.

FIG. 4 depicts an embodiment of a process by which a spherical urea-aldehyde condensate fertilizer is produced.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale.

DETAILED DESCRIPTION OF THE INVENTION

The spherical urea-aldehyde condensate fertilizer of the present invention provide an elegant solution to at least some of the problems associated with urea-aldehyde condensate fertilizers. The spherical urea-aldehyde condensate fertilizers can be formed as a sphere through granulation and/or spheronization and optionally can be extruded before spheronization. The granulation and/or spheronization can be performed after the chemical reactions that produce the urea-aldehyde condensate have been completed. The presence of an optional binder and/or flow promotor in the spherical urea-aldehyde condensate fertilizer can improve the production of the spherical urea-aldehyde condensate fertilizer. The spherical urea-aldehyde condensate fertilizers can have a consistent size. The blended fertilizers of the present invention can contain a plurality of the spherical urea-aldehyde condensate fertilizers in combination with other fertilizers or fertilizer ingredients.

These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Spherical Urea-Aldehyde Condensate Fertilizer

Illustrative cross section views of embodiments of a spherical urea-aldehyde condensate fertilizer of the present invention are depicted symbolically in FIG. 1. In the illustrated embodiment, the spherical urea-aldehyde condensate fertilizer 100 comprises an optional binder and/or flow promotor 101, and urea-aldehyde condensate 102. The spherical urea-aldehyde condensate fertilizer 200 comprises urea-aldehyde condensate 102. The spherical urea-aldehyde condensate fertilizer 100 and 200 have a circular cross-section. The spherical urea-aldehyde condensate fertilizer 100 and 200 may also comprise other ingredients, such as micronutrients, pH balancing agents, and/or thickeners, etc. In the illustration, and for illustrational purposes only, urea-aldehyde condensate 102 has a filled in circular cross section. The shapes, sizes, and relative numbers of the components in the illustration are used to assist in easily distinguishing the different components in the spherical urea-aldehyde condensate fertilizer 100 and 200 and are non-limiting. Other sizes and relative numbers of components are contemplated and can readily be made. In the illustrated spherical urea-aldehyde condensate fertilizer 100 embodiment, in certain aspects of the present invention, the binder and/or flow promotor 101 can act as a continuous phase that helps bind the urea-aldehyde condensate 102 and binder and/or flow promotor 101 together to form the spherical urea-aldehyde condensate fertilizer 100. In certain aspects no binder and/or flow promotor 101 is contained in the spherical urea-aldehyde condensate fertilizer 200. It will be apparent to persons of ordinary skill in the art that other configurations of the spherical urea-aldehyde condensate fertilizer 100 and 200 are possible. Although FIG. 1 represents a perfectly spherically-shaped fertilizer, it is contemplated in the context of the present invention that the spherically-shaped fertilizers can include substantially spherically-shaped fertilizers. Substantially spherical can include ellipsoidal shapes. Substantially spherical can include a ratio of the lengths across perpendicular axis of the particle cross-section including a ratio falling within the range of a ratio of 0.5 to a ratio of 2.0, preferably falling within a range of a ratio of 0.8 to a ratio of 1.2, more preferably falling within a range of a ratio of 0.9 to a ratio of 1.1, or having a ratio of about 1.0.

The spherical urea-aldehyde condensate fertilizer 100 and 200 can have a variety of sizes. In some embodiments, the spherical urea-aldehyde condensate fertilizer can have an average mean diameter between about 1 and 8 mm, 1 and 4 mm, or 2 and 3.5 mm, or any size therein.

B. Urea-Aldehyde Condensate

The urea-aldehyde condensate contains a C1-C4/urea oligomer. In some instances, the urea-aldehyde condensate contains a C2-C4/urea oligomer. In some instances the urea-aldehyde condensation contains a mixture of C1 and C4 aldehydes. The C1-C4 or C2-C4/urea oligomer can be any C1-C4 or C2-C4/urea oligomer. The C1-C4 and C2-C4 aldehydes of the spherical urea-aldehyde condensate can be any C1-C4 or C2-C4 aldehyde, derivative thereof, or combination thereof. In some instances, the C1-C4 or C2-C4 aldehydes can be formaldehyde, butyraldehyde, isobutyraldehyde, crotonaldehyde, or any combination thereof. In some instances, the condensates contain less than 25, 20, 15, 10, 5, 4, 3, 2, or 1 wt. % urea.

C. Binders and Flow Promotors

Binders can be used to bind together components in a mixture through adhesive and/or cohesive forces. The binder to be used in the spherical urea-aldehyde condensate fertilizer may be chosen for suitability in the granulation and/or spheronization or extrusion processes for making the spherical urea-aldehyde condensate fertilizer. Binders can be polymeric or non-polymeric binders. The binder can have a melting point or softening temperature below the temperature that the urea-aldehyde condensate contained in the spherical urea-aldehyde condensate fertilizer degrades or melts. In non-limiting examples, this temperature is below 50° C., below 40° C., below 30° C., below 20° C., or any temperature therein. In some instances, the binders are biodegradable. In some instances the binders are water soluble.

Non-limiting examples of binders include bleached wheat flour, gaur gum, calcium ligno sulfonate, gelatin, seaweed extract, plaster of paris, flour, starch, cellulose, gluten, colloidal silica, kaolin, bentonite, poly ethylene glycol (PEG), polycaprolactone, low molecular weight poly vinyl acetate, 60 wt. % urea solution, polyacrylamide, polyacrylic acid, polyacrylonitrile, hydroxypropyl methylcellulose (HPMC), biodegradable polylactic acid, and other biodegradable polymeric material such as polylactic acid, poly(3-hydroxypropionic acid), polyvinyl alcohol, poly e-caprolactone, poly L-lactide, poly butylene succinate, and biodegradable starch based polymers.

Flow promotors can be used to increase the flow of a urea-aldehyde condensate or increase the ability to granulate and/or spheronize the urea-aldehyde condensate. The flow promotor to be used in the spherical urea-aldehyde condensate fertilizer may be chosen for suitability in the granulation and/or spheronization or extrusion processes for making the spherical urea-aldehyde condensate fertilizer. Flow promotors can be polymeric or non-polymeric.

Non-limiting examples of flow promotors include bleached wheat flour, microcrystalline silica, chitosan, natural gums such as agar, gaur gum, clays such as bentonite, cellulose derivatives such as carboxy methyl cellulose, methyl cellulose, ethyl cellulose, hydroxyl ethyl cellulose, and hydroxypropyl methylcellulose (HPMC).

The spherical urea-aldehyde condensate fertilizer can contain any amount of binder and/or flow promotor. The spherical urea-aldehyde condensate fertilizer can have a sufficient amount of a binder to bind together the spherical fertilizer or an extrudate used to create the spherical fertilizer. The spherical urea-aldehyde condensate fertilizer can have a sufficient amount of a flow promotor to increase the flow of a urea-aldehyde condensate through an extruder. The concentration of the binder and/or flow promotor can be 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1 wt. %, or any concentration or range therein based on the total weight of the spherical urea-aldehyde condensate fertilizer. In preferred embodiments, the spherical urea-aldehyde condensate fertilizer contains 0.2 wt. % to 5 wt. %, more preferably 0.5 wt. % to 1 wt. %, or any value or range therein, of the binder and/or flow promotor. In some instances, no binder and/or flow promotor is used in the spherical urea-aldehyde condensate fertilizer.

Spherical urea-aldehyde condensate fertilizers of the present invention can have desirable physical properties such as desired levels of abrasion resistance, strength, pelletizability, hygroscopicity, shape, and/or size distribution. Accordingly, the binder and/or flow promotor may be chosen to optimize these properties.

D. Additional Fertilizers

Additional fertilizer substances besides urea-aldehyde condensate may be included in the spherical urea-aldehyde condensate fertilizer or used in a fertilizer composition or blend of the present invention. Additional fertilizers can be chosen based on the particular needs of certain types of soil, climate, or other growing conditions to maximize the efficacy of the spherical urea-aldehyde condensate fertilizer in enhancing plant growth and crop yield. Additional additives may also be included in the spherical urea-aldehyde condensate fertilizer or used in a fertilizer composition or blend of the present invention, including without limitation micronutrients, primary nutrients, and secondary nutrients. A micronutrient can be a botanically acceptable form of an inorganic or organometallic compound such as boron, copper, iron, chloride, manganese, molybdenum, nickel, or zinc. A primary nutrient can be a material that can deliver nitrogen, phosphorous, and/or potassium to a plant. Nitrogen-containing primary nutrients may include urea, ammonium nitrate, ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea-formaldehyde, or combinations thereof. A secondary nutrient can be a substance that can deliver calcium, magnesium, and/or sulfur to a plant. Secondary nutrients may include lime, gypsum, superphosphate, or a combination thereof.

E. pH Buffering Agents

The spherical urea-aldehyde condensate fertilizer of the present invention may also contain one or more pH buffering agents. Examples of suitable pH buffering agents include, but are not limited to, CaCO₃, MgO, KH₂PO₄, NaHCO₃, chalk powder, aluminum, magnesium hydroxide, aluminum hydroxide, sodium bicarbonate etc. and combinations thereof.

F. Blended Fertilizer

The spherical urea-aldehyde condensate fertilizer of the present invention can also be included in a blended composition comprising other fertilizers, such as other fertilizer granules. Additional fertilizers can be chosen based on the particular needs of certain types of soil, climate, or other growing conditions to maximize the efficacy of the blended composition in enhancing plant growth and crop yield. FIG. 3 illustrates an embodiment of a process 300 by which a blended fertilizer can be produced. By way of example, spherical urea aldehyde condensate fertilizers 100, 200 of the present invention can be blended with non-spherical non-urea aldehyde condensate fertilizers 301. Blending 302 can be performed by any type of blending or mixing apparatus generally available in the art (e.g., WJ-700, WJ-900, or WJ-1000 Mixing Machines from Whirlston Machinery (Zhengzhou, China). Once blended, the fertilizer blend can be stored 303 for future use or sale.

The spherical urea-aldehyde condensate fertilizers can be blended with other fertilizer at any concentration. In some instances, the desired concentration is sufficient to meet the required nutrient or micronutrient content in the blend.

G. Method of Making a Spherical Urea-Aldehyde Condensate Fertilizer and a Blended Fertilizer

In some embodiments, the spherical urea-aldehyde condensate fertilizer is made by combining a urea-aldehyde condensate and water and optionally one or more of a flow promotor, a binder, a micronutrient, and/or a combination thereof. In some instances, other suitable substances such as pH balancing agents, and other additives are also combined. The mixture can be optionally extruded. The extrudate can be formed by mixing the ingredients in dry form, adding any solvent, if needed, and further mixing to make an extrudable composition. A solvent, such as water, may be needed to make an extrudable composition. The extrusion can be done using a suitable extruder apparatus known in the art and can be performed at a temperature between 0° C. and 50° C., a screw speed from 20 to 300 rpm, a pressure of 1 bar to 50 bar, and/or wherein the extruder comprises a multi-feeder comprising extrusion components including a main drive, shaft, screw, barrel, and/or die. In some embodiments, the extrusion method comprises slicing the extrudate. The extrudate can be sliced by the use of a die or by other methods known in the art. The die can be a perforated die.

In some embodiments, the spherical urea-aldehyde condensate fertilizer is made by forming a spherical urea-aldehyde condensate fertilizer from a non-extruded combination of ingredients or from the extrudate. The spherical urea-aldehyde condensate fertilizer can have a diameter between about 1 and 4 mm. The spherical urea-aldehyde condensate fertilizer can have a substantially spherical shape. In some instances, the sphere can be formed by granulation and/or by use of a spheronizer. The granulation and/or spheronization can be performed after the chemical reactions that produce the urea-aldehyde condensate have been completed and/or after a dried fertilizer has been formed. The granulator can be any suitable granulator, such as a pan granulator or a drum granulator. The spheronizer can be any suitable spheronizer. The spheronizer can be a disc spheronizer. In some instances, the disk can have a cross-hatched chequered pattern. The spheronizer can be operated with an air pressure of 0.5 bar to 10 bar and/or a speed of 1 rpm to 5000 rpm.

The spherical urea-aldehyde condensate fertilizer can be made by use of a granulator or use of a spheronizer after granulation. The granulation can be carried out in any suitable granulator. Non-limiting examples of granulators include pan granulators or drum granulators. To make the spherical granulated urea-aldehyde condensate fertilizer, the spherical urea-aldehyde condensate fertilizer ingredients, which can include urea-aldehyde condensate and none or one or more of water, a binder, a flow promotor, or other suitable ingredients can be mixed and granulated. In some instances, granulation is carried out using powdered urea-aldehyde condensate(s) and water. The granulator can be configured to tumble and heat the ingredients in a rotating granulator under heat resulting in aggregation of the ingredients and formation of a granule. In some instances, the granulator is operated at a rotation speed of 500 RPM to 10 RPM and operated with air flow having a pressure of 0.1 bar to 10 bar and a temperature of 40° C. to 100° C. The granulation process can be performed for any amount of time, such as 1 to 15 minutes.