BACKGROUND

[0001] Granular fertilizers are widely used to increase plant growth. Granular fertilizers can comprise a seed core. The production of the fertilizer seed core by extrusion can be problematic. Issues arrive with seed core integrity, material flow and pelletization, particularly when the extrusion composition is thixotropic. Accordingly, there is a need in the art for a method of making fertilizer seed cores by extrusion.

SUMMARY

[0002] Disclosed herein is a method of making a fertilizer seed core, the method comprising: supplying a fertilizer component, a liquid component, a binder and a filler to a zoned extruder comprising a die head, a screw, and at least three zones; mixing the fertilizer component, liquid component, binder and filler to yield a thixotropic mixture; and passing the thixotropic mixture through the die head, wherein the die head comprises openings 0.5 to 4 millimeter in diameter and wherein the end of the screw is 1 to 15 millimeters from the die head.

[0003] Also disclosed herein is a method of making a fertilizer seed core, the method comprising: supplying a fertilizer component, a liquid component, a binder and a filler to a zoned extruder comprising a die head, a screw, and at least three zones; mixing the fertilizer component, liquid component, binder and filler to yield a thixotropic mixture; and passing the thixotropic mixture through the die head, wherein the die head comprises openings 0.5 to 4 millimeter in diameter and wherein the extrusion process has a residence time of 5 seconds to 15 minutes.

[0004] The above described and other features are further set forth in the following figures, detailed description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The following figures are exemplary embodiments wherein the like elements are numbered alike.

[0006] FIG. 1 is a representation of the intake side of a die head having conical openings.

[0007] FIG 2 is a transverse view along line A -A of Figure 1. [0008] FIG. 3 is a representation of the intake side of a die head having cylindrical openings.

DETAILED DESCRIPTION

[0009] According to the method of making a fertilizer seed core, a fertilizer component, a liquid component, e.g., an aqueous component, binder, filler, and optional additives are supplied to an extruder having at least three zones. The method can include supplying a viscoelastic agent to the agent. The binder, when mixed with the liquid component, forms a mixture which decreases viscosity when subjected to shear stress. The decrease in viscosity results in issues of seed core integrity, material flow and pelletization. It has been found that extrusion can be effectively achieved by supplying the liquid component to the extruder simultaneously with the binder or after the binder. When the liquid component is supplied to the extruder before the binder issues arise with the unequal distribution of components of the composition and uneven density, sometimes even resulting in lumps in the composition.

[0010] The dry ingredients, namely the fertilizer component, the binder, the filler and any dry additives, may be added to the extruder sequentially or simultaneously. In some embodiments the fertilizer component and the binder are dry mixed prior to being supplied to the extruder. Any dry additives can be included in the dry mix. Alternatively any dry additives can be supplied to the extruder simultaneously or sequentially with the dry mix.

[0011] The liquid ingredients, namely the liquid component and any liquid additives, can be added with some or all of the dry ingredients as long as the binder is added before the liquid component or simultaneously with the liquid component.

[0012] In some embodiments, the fertilizer component, the binder and any dry additives are supplied to the first zone of the extruder to form a first composition which is mixed as it is moved to a second zone of the extruder where the liquid component is supplied to the extruder to form a second composition. The second composition is mixed as it is moved to the die head. The first and second zones may be operated at a temperature of 0 to 70 degrees Celsius, for example, 0 to 40 degrees Celsius. In some embodiments the temperature of the first and second zones is substantially the same. The die head may be operated at a temperature of 0 to 70 degrees Celsius.

[0013] The term "first zone" and "second zone" as used in this context does not exclude extruder designs where the first zone or second zone consists of two or more separate zones of the extruder with the proviso that the second zone is downstream of the first zone. Additionally, it is expressly contemplated that an additional zone or zones may intervene between the first zone and second zone.

[0014] In some embodiments the die head has a dead space of 1 to 6 millimeters (mm), or 7 to 10 mm, or 1 to 15 mm. The dead space is the distance between the end of the extruder screw and the die head. Additionally, the die head can comprise eccentric openings. When the openings are eccentric the diameter of the openings refers to the longest linear dimension. This is shown in FIG 1 as "D". The die head openings can have a diameter of 0.5 to 4.0 millimeters on the outflow side. The land length of the die head openings (the distance from the inside of the extruder to the outside of the extruder) can be 3to 10 mm, or 10 to 16 mm, or 3 to 16 mm. The die head openings can be conical or cylindrical. Conical openings have a broader opening at the intake and narrow to a smaller opening at the outflow. The outflow openings can have a diameter that is 30 to 100% of the intake openings. Within this range the outflow openings can have a diameter that is 30 to 70%, or, 50 to 100% of the intake openings. The conical openings can have an angle, 40, of 40 to 45 degrees.

Cylindrical openings have substantially the same size opening at the intake and outflow locations.

[0015] Turning now to FIG 1, an exemplary die head 10 is shown with circular openings 20. The die head is shown from the intake side. A cross section of the die head taken along line A-A is shown in FIG 2. FIG 2 shows the die head 10 having conical openings 20. The conical openings have an angle 40 and a length 30. The arrow shows the direction of flow for the thixotropic composition. FIG 3 shows a die head 10 having cylindrical openings 20.

[0016] In some embodiments the die head comprises a cooling jacket in which a coolant such as water is circulated around the die head openings at a temperature of 0 degrees Celsius to room temperature (typically 25 degrees Celsius).

[0017] After leaving the die head, the thixotropic mixture is cut into pellets. In some embodiments, the mixture is cut into pellets immediately upon leaving the die head (at the die face) using a knife. The knife can be of any shape or design required to obtain the desired pellet size. In some embodiments the knife comprises 2 or more blades.

[0018] The fertilizer component comprises an inhibitor, a micronutrient or a combination comprising at least one of the foregoing. The inhibitor can comprise a urease inhibitor, a nitrification inhibitor or a combination comprising at least one of the foregoing. Exemplary inhibitors include N-(n-butyl)thiophosphoric triamide (NBTPT), 3,4- dimethylpyrazole phosphate (DMPP), thio-urea (TU), dicyandiamide (DCD), phenyl phosphorodiamidate (PPDA), 2-chloro-6-(trichloromethyl)-pyridine (nitrapyrin), 5-ethoxy-3- trichloromethyl-l,2,4-thiadiazol (terrazole), 2-amino-4-chloro-6-methyl-pyrimidine (AM), 2- mercapto-benzothiazole (MBT), 2-sulfaminalamidothiazole (ST), and combinations comprising at least one of the foregoing.

[0019] A micronutrient is a botanically acceptable form of a compound comprising boron (B), copper (Cu), iron (Fe), chloride (CI), manganese (Mn), molybdenum (Mo), nickel (Ni), zinc (Zn) or a combination comprising at least one of the foregoing. Exemplary inorganic compounds include sulfate, oxides and salt. Specific examples include borax, anyhydrous sodium tetraborate, sodium tetraborate pentahydrate, sodium tetraborate decahydrate, potassium metaborates, potassium tetraborates, potassium peroxyborates, calcium metaborates, ammonium pentaborates, ammonium tetraborates, CuS0 ₄ , and ZnS0 ₄ . Exemplary organic compounds include Fe EDTA, Fe EDDHA, Ca EDTA, Zn EDTA, and Mn EDTA. EDTA is an acronym for ethylenediaminetetraacetate and EDDHA is an acronym for ethylenediamine-N,N'-bis(2-hydroxyphenylacetate).

[0020] The fertilizer component is present in an amount of 0.25 to 55 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler.

[0021] In some embodiments the fertilizer component comprises NBTPT. The NBTPT can be present in an amount of 0.25 to 6.0 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler. Within this range, the amount of NBTPT can be 0.8 to 2.2 weight percent.

[0022] In some embodiments the fertilizer component comprises DCD. The DCD can be present in an amount of 10 to 45 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler. Within this range, the amount of DCD can be 15 to 25 weight percent.

[0023] In some embodiments the fertilizer component comprises a combination of NBTPT and DCD. In these embodiments the combination of NBTPT and DCD can be present in an amount of 11 to 47 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler. Within this range, the amount of NBTPT can be 0.8 to 2.2 weight percent and the amount of DCD can be 15 to 25 weight percent. The combined amount of NBTPT and DCD can be 24 to 27 weight percent.

[0024] The binder comprises Plaster of Paris, flour, starch, cellulose, gluten, colloidal silica, kaolin, bentonite, polyethylene glycol (PEG), polycaprolactone, low molecular weight polyvinyl acetate, or a combination comprising at least one of the foregoing. The binder is present in an amount of 25 to 90 weight percent based on the combined weight of the fertilizer component, liquid component, binder and filler.

[0025] The liquid component, e.g., aqueous component, comprises water and any optional liquid additives. It is also contemplated that optional solid additives may be at least partially dissolved in the liquid component with the proviso that the liquid component has a solids content of less than or equal to 10%. The liquid component is present in an amount of 7 to 25 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler. Within this range the liquid composition may be present in an amount of 7 to 11, 11 to 16, or 20 to 25 weight percent.

[0026] In some embodiments the weight ratio of liquid component to binder is 5 to 30. Within this range the weight ratio can be 5 to 15, 10 to 20, or 15 to 30.

[0027] The filler comprises chalk powder, silica, rice husk, dried distillers grains with solubles (DDGS), calcite, calcium oxide, dolomite, talc, calcium carbonate, sand, chalk powder, sodium carbonate (Na ₂ C0 ₃ ), potassium carbonate (K ₂ C0 ₃ ), magnesium oxide (MgO), monopotassium phosphate (KH ₂ P0 ₄ ), sodium bicarbonate (NaHC0 ₃ ), or a combination comprising one or more of the foregoing. The filler is a material which can facilitate the release of inhibitors, micronutrients or both from the seed core. The filler can also help improve the properties of the core. The filler is a dry ingredient and hence may be supplied as described above with regard to dry ingredients. The filler is present in an amount of 5 to 50 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler. Within this range the filler may be present in an amount of 5 to 20, 15 to 30, or 30 to 50 weight percent.

[0028] Additives can include viscoelastic agents, e.g., a polymer thickener, such as hydroxyl propyl methyl cellulose, polyethylene glycol, or a combination comprising at least one of the foregoing.

[0029] Optional additives can include, for example, surfactants, nucleation agents, recycled fertilizer particles, nucleating soil conditioners such as activated carbon, elemental sulfur, biocides such as pesticides, herbicides, or fungicides, wicking agents, wetting agents, heat stabilizers, adhesives such as cellulose, polyvinyl alcohols, fats, oils, gum arables, vinylidene ultraviolet stabilizers, antioxidants, reducing agents, colorants, alternative binders (i.e., organochlorides, zeins, gelatins, chitosan, polyethylene oxide polymers, and acrylamide polymers and copolymers), and the like, as well as combinations comprising at least one of the foregoing. [0030] The fertilizer seed core can have any shape or size desired for their intended use. The fertilizer seed cores have an average particle diameter of 0.5 to 4.0 millimeters (mm). Within this range the average particle diameter can be greater than or equal to 0.75, or greater than or equal to 1.0 mm. Also within this range the average particle diameter can be less than or equal to 3.5 mm, or less than or equal to 3.0 mm. In some embodiments at least 90% by weight of the fertilizer seed cores have a particle diameter of 0.6 to 1.4 mm, for example 0.7 to 1.2 mm. Particle diameter is determined according to "Size Analysis - Sieve Method" IFDC S-107 issued by International Fertilizer Development Center (IFDC) which is the most common and internationally approved method used to determine fertilizer particle size.

[0031] The fertilizer seed cores are subsequently fattened with additional components such as urea and/or excrement to produce a fertilizer granule. By incorporating the fertilizer components such as inhibitors and micronutrients into the seed core these components are protected from degradation resulting from conditions required for subsequent processing steps.

[0032] The method and extruders disclosed herein include at least the following embodiments:

[0033] Embodiment 1: A method of making a fertilizer seed core, the method comprising: supplying a fertilizer component, an liquid component, a binder and a filler to a zoned extruder comprising a die head, a screw, and at least three zones; mixing the fertilizer component, liquid component, binder and filler to yield a thixotropic mixture; and passing the thixotropic mixture through the die head, wherein the die head comprises openings 0.5 to 4 millimeter in diameter and wherein the end of the screw is 1-15 millimeters from the die head.

[0034] Embodiment 2: The method of embodiment 1, wherein the die head openings have a land length of 3 to 16 millimeters.

[0035] Embodiment 3: The method of embodiment 1 or 2, wherein the fertilizer component is supplied to the extruder and the liquid component and binder are supplied to the extruder following the fertilizer component.

[0036] Embodiment 4: The method of embodiment 1 or 2, wherein the fertilizer component and the binder are supplied to the extruder and the liquid component is supplied to the extruder following the fertilizer component and the binder. [0037] Embodiment 5: The method of embodiment 4, wherein the fertilizer component and the binder are supplied to a first zone of the extruder and the liquid component is supplied to a second zone downstream of the first zone.

[0038] Embodiment 6: The method of any one of embodiments 1-5, wherein the binder is present in an amount of 25 to 90 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler.

[0039] Embodiment 7: The method of any one of embodiments 1-6, wherein the liquid component is present in an amount of 7 to 25 weight percent, based on the combined weight of the fertilizer component, liquid component, binder and filler.

[0040] Embodiment 8: The method of any of the preceding embodiments, wherein the filler comprises chalk powder, silica, , rice husk, dried distillers grains with solubles (DDGS), , calcite, calcium oxide, calcium carbonate, dolomite, talc, sand, chalk powder, sodium carbonate, potassium carbonate, magnesium oxide, monopotassium phosphate, sodium bicarbonate, or a combination comprising one or more of the foregoing.

[0041] Embodiment 9: The method of any of the preceding embodiments, wherein the filler is present in an amount of 5 to 50 weight percent, based on the combined weight of the fertilizer component, liquid component, binder, and filler.

[0042] Embodiment 10: The method of any of the preceding embodiments, wherein the fertilizer component comprises a micronutrient, an inhibitor, or a combination comprising at least one of the foregoing.

[0043] Embodiment 11: The method of any of the preceding embodiments, wherein the binder comprises Plaster of Paris, flour, starch, cellulose, gluten, colloidal silica, kaolin, bentonite, or a combination comprising at least one of the foregoing.

[0044] Embodiment 12: The method of any of the preceding embodiments, wherein the liquid component comprises an aqueous component.

[0045] Embodiment 13, The method of any of the preceding embodiments, further comprising supplying a viscoelastic agent to the zoned extruder.

[0046] Embodiment 14: A method of making a fertilizer seed core, the method comprising: supplying a fertilizer component, an liquid component, a binder and a filler to a zoned extruder comprising a die head, a screw, and at least three zones; mixing the fertilizer component, liquid component, binder and filler to yield a thixotropic mixture; and passing the thixotropic mixture through the die head, wherein the die head comprises openings 0.5 to 4 millimeter in diameter and wherein the extrusion process has a residence of 5 seconds to 15 minutes. [0047] Embodiment 15: The method of embodiment 14, wherein the fertilizer component is supplied to the extruder and the liquid component and binder are supplied to the extruder following the fertilizer component.

[0048] Embodiment 16: The method of embodiment 14, wherein the fertilizer component and the binder are supplied to the extruder and the liquid component is supplied to the extruder following the fertilizer component and the binder.

[0049] Embodiment 17: The method of embodiment 16, wherein the fertilizer component and the binder are supplied to a first zone of the extruder and the liquid component is supplied to a second zone downstream of the first zone.

[0050] Embodiment 18: The method of any of Embodiments 14-17, wherein the liquid component comprises an aqueous component.

[0051] Embodiment 19: The method of any of Embodiments 14-18, further comprising supplying a viscoelastic agent to the zoned extrude.

[0052] Embodiment 20: An extruder for performing the method of any of the preceding embodiments, wherein the extruder comprises a die head having openings with a land length of 3 to 16 millimeters.

[0053] Embodiment 21: The extruder of embodiment 20, wherein the die head comprises eccentric openings.

[0054] Embodiment 22: The extruder of embodiments 20 or 21, wherein the die head openings are conical.

[0055] Embodiment 23: The extruder of embodiment 22, wherein the die head has out flow openings having a diameter that is 30 to 70% of the intake opening diameter.

[0056] Embodiment 24: The extruder of any of embodiments 20-23, wherein the die head comprises a cooling jacket.

[0057] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. "Or" means "and/or." The endpoints of all ranges directed to the same component or property are inclusive and independently combinable. The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., "colorant(s)" includes at least one colorant). "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. Substantially as described herein generally refers to greater than or equal to 75%, for example, greater than or equal to 75%, for example, greater than or equal to 95%.

[0058] As used herein, a "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash ("-") that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through carbon of the carbonyl group.

[0059] All references cited herein are incorporated by reference in their entirety. While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.