BR112018007053B1 - AQUEOUS DISPERSIONS OF CALCIUM AND POTASSIUM POLYPHOSPHATE AND METHOD FOR PREPARING A FLUID LIQUID FERTILIZER - Google Patents

Abstract

AQUEOUS DISPERSIONS OF CALCIUM AND POTASSIUM POLYPHOSPHATE. Aqueous dispersion comprising water and calcium and potassium polyphosphate dispersed in water.

Description

[001] This application claims the benefit of provisional patent application No. US 62/238,889, filed on October 8, 2015, which is incorporated herein by reference.

FIELD OF INVENTION

[002] Embodiments of the present invention are directed to stable aqueous dispersions of calcium and potassium polyphosphate. Other embodiments are directed to ways of preparing stable aqueous dispersions of potassium and calcium polyphosphate, and still other embodiments are directed to using stable dispersions of potassium and calcium polyphosphate as a liquid fertilizer.

BACKGROUND OF THE INVENTION

[003] Divalent metal phosphates have been proposed as fertilizers. These compounds advantageously provide various nutrients and exhibit slow and controlled release properties. To date, divalent metal phosphates have been produced as solid materials and therefore techniques for their use as plant nutrients have been limited to the application of solids in the form of, for example, pellets. For example, Patent No. US 5,374,294 describes a controlled slow release potassium divalent metal phosphate composition. These compositions are prepared by co-reaction of concentrated potassium hydroxide, divalent metal oxide powder and concentrated phosphoric acid. This reaction produces a dry, particulate, water-insoluble divalent metal potassium phosphate.

SUMMARY OF THE INVENTION

[004] One or more embodiments of the present invention provide an aqueous dispersion comprising water and calcium and potassium polyphosphate dispersed in water.

[005] Other embodiments provide a process for preparing a fluid liquid fertilizer comprising the steps of providing a solution of potassium polyphosphate and introducing a water-soluble calcium salt into the aqueous solution of tetrapotassium pyrophosphate to form the fluid liquid fertilizer in the form of an aqueous dispersion.

[006] Still other embodiments of the present invention provide a method of applying dipotassium calcium pyrophosphate as a fertilizer for plants comprising providing an aqueous dispersion of calcium and potassium polyphosphate; and apply the aqueous dispersion of calcium and potassium polyphosphate to the plant.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

[007] Embodiments of the invention are based, at least in part, on the discovery of a stable aqueous dispersion of calcium and potassium polyphosphates (for example, dipotassium calcium pyrophosphate). The aqueous dispersion is prepared solely in a step reaction, first providing an aqueous solution of a potassium polyphosphate, and then introducing a water-soluble calcium salt into the solution to form the aqueous dispersion. Thus, although calcium and potassium polyphosphates are appreciably insoluble in water, it has unexpectedly been found that stable flowable aqueous dispersions can be obtained by practicing embodiments of this invention. Stable aqueous dispersions advantageously provide new methods for providing nutrients to plants through a liquid fertilizer.

Method for producing aqueous dispersion

[008] As indicated above, aqueous dispersions of potassium and calcium polyphosphate are prepared by a method including (i) providing an aqueous solution of a potassium polyphosphate, and (ii) introducing a water-soluble calcium salt into the aqueous solution to thereby form the aqueous dispersion. In these or other embodiments, agrochemicals (e.g., plant nutrition compounds, plant growth regulators, and/or beneficial plant microbes) may be added to the aqueous dispersion.

Preparation of tetrapotassium pyrophosphate solution

[009] In one or more embodiments, the potassium polyphosphate is a tetrapotassium pyrophosphate. In one or more embodiments, an aqueous solution of tetrapotassium pyrophosphate is prepared by simply dissolving tetrapotassium pyrophosphate in water. Advantageously, tetrapotassium pyrophosphate dissolves easily in water. In other embodiments, the desired potassium polyphosphate, such as tetrapotassium pyrophosphate, can be formed in situ; in other words, it is formed within the water to form the aqueous solution. For example, acid dipotassium pyrophosphate can be added to water with potassium hydroxide to provide the desired aqueous solution. Alternatively, pure pyrophosphoric acid can be combined with an appropriate amount of potassium hydroxide to provide the desired aqueous solution.

[0010] In one or more embodiments, the concentration of tetrapotassium pyrophosphate in the aqueous solution can be described based on the parts by weight of tetrapotassium pyrophosphate in relation to water. In one or more embodiments, the tetrapotassium pyrophosphate solution includes at least 10, in other embodiments at least 50, in other embodiments at least 100, in other embodiments at least 150, and in other embodiments at least 200 parts by weight of tetrapotassium pyrophosphate. tetrapotassium per 100 parts by weight of water. In these or other embodiments, the solution of tetrapotassium pyrophosphate includes a maximum of 1000, in other embodiments a maximum of 500, in other embodiments a maximum of 350, in other embodiments a maximum of 300, and in other embodiments a maximum of 250 parts by weight of tetrapotassium pyrophosphate. tetrapotassium per 100 parts by weight of water. In one or more embodiments, the tetrapotassium pyrophosphate solution includes from about 10 to about 1000, in other embodiments from about 150 to about 300, and in other embodiments from about 200 to about 250 parts by weight of tetrapotassium pyrophosphate per 100 parts by weight of water.

[0011] In one or more embodiments, the preparation of the tetrapotassium pyrophosphate solution can occur under standard conditions. For example, in particular embodiments, the solution may be prepared at room temperature. In one or more embodiments, the tetrapotassium pyrophosphate solution may be prepared at temperatures less than 150, in other embodiments less than 125, in other embodiments less than 100, in other embodiments less than 80, in other embodiments less than 60, and other modalities below 40 °C. In these or other embodiments, the tetrapotassium pyrophosphate solution may be prepared at temperatures greater than 20°C, in other embodiments greater than 30°C, in other embodiments greater than 40°C, in other embodiments greater than 50°C, and in other embodiments greater than 60°C. °C. In particular embodiments, the temperature of the tetrapotassium pyrophosphate solution during preparation can be maintained within a narrow temperature range; for example, the temperature can be maintained within +/- 15, in other modalities +/- 10, in other modalities +/- 5, and in other modalities +/- 3 °C.

[0012] In one or more embodiments, the preparation of the tetrapotassium pyrophosphate solution can occur at atmospheric pressure. In other embodiments, the solution may be prepared under vacuum, for example, less than 0.5 atmospheres, or in other embodiments, for example, less than 0.25 atmospheres. In still other embodiments, the solution can be prepared at elevated pressures. In one or more embodiments, the solution may be prepared using conventional emulsification techniques and equipment.

Introduction of water-soluble calcium salt

[0013] As indicated above, a water-soluble calcium salt is introduced into the aqueous solution of potassium polyphosphate (for example, tetrapotassium pyrophosphate). Again, without wishing to be bound by any particular theory, it is believed that potassium polyphosphate and water-soluble calcium salt react or interact to produce dipotassium calcium pyrophosphate, which can be represented by the molecular formula CaK2P2O7 . Embodiments of the invention, however, are not limited by the exact structure or purity of the dipotassium calcium pyrophosphate produced. To the skilled artisan, it is clear that optimization of the stated ratios and reaction conditions of this invention may produce a slightly different composition of calcium and potassium polyphosphate. For example, one such form may be an aqueous dispersion mixture of colloids of monomeric CaK2P2O7 species and polymeric Ca10K4(P2O7)6 species at varying concentrations of each molecule. The term “dipotassium calcium pyrophosphate” will, however, be used to refer to this reaction product.

[0014] In one or more embodiments, the water-soluble calcium salt may include calcium acetate, calcium thiosulfate, calcium formate, calcium nitrate, calcium chloride or mixtures of two or more thereof. In particular embodiments, anhydrous calcium acetate is used. In one or more embodiments, the anhydrous calcium acetate may be characterized by a purity of at least 98% or in other embodiments, at least 99%. In other embodiments, calcium acetate monohydrate is used. In other particular embodiments, calcium chloride and calcium acetate are used in combination, which combination advantageously addresses both solubility and cost concerns.

[0015] In one or more embodiments, the amount of water-soluble calcium salt (e.g., calcium acetate) introduced into the aqueous tetrapotassium pyrophosphate mixture can be described based on the molar ratio of the moles of calcium within the water-soluble calcium salt to moles of phosphorus within tetrapotassium pyrophosphate (i.e., moles of Ca to moles of P). In one or more embodiments, the molar ratio of moles of calcium within the water-soluble calcium salt to moles of phosphorus in the tetrapotassium pyrophosphate may be at least 1:0.5, in other embodiments at least 1:1. in other embodiments at least 1:2, in other embodiments at least 1:3, and in other embodiments at least 1:3.5. In one or more embodiments, the molar ratio of moles of calcium within the water-soluble calcium salt to moles of phosphorus within the tetrapotassium pyrophosphate may be a maximum of 1:10, in other embodiments a maximum of 1:7, in other embodiments maximum 1:6, in other modalities maximum 1:5 and in other modalities maximum 1:4.5. In one or more embodiments, the molar ratio of moles of calcium within the water-soluble calcium salt to moles of phosphorus within the tetrapotassium pyrophosphate may be from about 1:1 to about 1:7, in other embodiments from about from 1:2 to about 1:6, in other embodiments from about 1:3 to about 1:5, and in other embodiments from about 1:3.5 to about 1:4.5.

[0016] In one or more embodiments, the preparation of dipotassium calcium pyrophosphate (i.e., the step of adding water-soluble calcium salt and subsequent reaction) can occur under standard conditions. This may include the temperature of the aqueous potassium polyphosphate solution at the time the water-soluble calcium salt is introduced. This may also include the temperature at which the reaction mixture and/or product is stirred after addition of the water-soluble calcium salt. For example, in particular embodiments, dipotassium calcium pyrophosphate can be prepared at room temperature. In one or more embodiments, the dipotassium calcium pyrophosphate may be prepared at temperatures below 150°C, in other embodiments below 125°C, in other embodiments below 100°C, in other embodiments below 80°C , other modalities below 60 °C and in other modalities below 40 °C. In these or other embodiments, dipotassium calcium pyrophosphate may be prepared at temperatures greater than 20°C, in other embodiments greater than 30°C, in other embodiments greater than 40°C, in other embodiments greater than 50°C, and in other modalities above 60 °C. In particular embodiments, the temperature of the reaction mixture can be maintained within a narrow temperature range; for example, the temperature can be maintained within +/- 15, in other modalities +/- 10, in other modalities +/- 5, and in other modalities +/- 3 °C.

[0017] In one or more embodiments, the preparation of dipotassium calcium pyrophosphate can occur at atmospheric pressure. In other embodiments, the dipotassium calcium pyrophosphate may be prepared under vacuum at, for example, less than 0.5 atmospheres, or in other embodiments at, for example, less than 0.25 atmospheres. In still other embodiments, the mixture can be prepared at elevated pressures.

[0018] In one or more embodiments, dipotassium calcium pyrophosphate can be prepared using conventional mixing techniques and equipment. In one or more embodiments, the aqueous potassium polyphosphate solution may be stirred during the introduction of the water-soluble calcium salt. This may include high shear mixing or high intensity mixing, which may be provided, for example, by rotor-stator mixers, homogenizers, colloidal mills or ultra-high shear mixers. Likewise, the resulting mixture and/or reaction product can be mixed using conventional mixing techniques. In one or more embodiments, the resulting mixture and/or reaction product may be agitated to achieve a desired particle size. This mixing, which follows the introduction of the water-soluble calcium salt, may include high shear mixing, which may be provided by rotor-stator mixers, homogenizers, colloidal mills or ultra-high shear mixers. In one or more embodiments, the resulting mixture and/or reaction product is subjected to emulsification. In one or more embodiments, emulsification is employed to prepare the tetrapotassium pyrophosphate solution. In these or other embodiments, emulsification is employed during the introduction of the water-soluble calcium salt. In one or more embodiments, emulsification is employed after introducing the water-soluble calcium salt. Although it has been found that the nature of the reactants and the relative amounts of the reactants ultimately determine the particle size that can be achieved, the skilled artisan will appreciate this mixing intensity, particularly the mixing intensity imparted in the resulting mixture and/or product. reaction, is inversely proportional to the time that may be required for the particular level of agitation to provide the desired particle size at any given mixing temperature.

[0019] In one or more embodiments, the pH of the aqueous calcium pyrophosphate dispersion can be adjusted to achieve a desired pH. This can be achieved by adding, for example, an organic acid. Useful organic acids include glacial acetic acid, acetic acid solution (e.g., 90% solution), formic acid, maleic acid, succinic acid, propionic acid, citric acid, or combinations of two or more of these acids. pH adjustment can occur before or after the addition of other optional agrochemicals.

[0020] After formation of the dipotassium calcium pyrophosphate, and optionally after adjusting the pH of the dispersion, other ingredients can be added to the aqueous dispersion. These other constituents may include constituents and/or adjuvants that are conventional in the art. For example, one or more biocides may be included, such as, but not limited to, hexahydro-1,3,5-tris(2-hydroxyethyl)-syntriazine, which is available under the trade names Glokill 77 or Emulcid. In these or other embodiments, one or more antifoam agents may be introduced. Useful antifoam agents include, but are not limited to, polydimethylsiloxane, which is available under the trade names Gensil 2030, Silfax and Ziameter. The skilled artisan will be able to readily determine an appropriate amount of other constituents and/or adjuvants based on desired needs.

Addition of optional agrochemicals

[0021] As indicated above, one or more agrochemicals can be added to the aqueous dispersion. For example, plant nutrition compounds, plant growth regulators, plant beneficial microbes, soil conditioners and/or plant biostimulants can be added to the aqueous dispersion. The amount of these chemicals added to the aqueous dispersion can be varied based on several factors such as, but not limited to, crop type, growth stage or soil type and known nutrient status of the soil.

[0022] In one or more embodiments, useful plant nutrition compounds include nitrogen sources. Exemplary nitrogen substitutes, including controlled-release nitrogen sources, include urea, potassium nitrate, ammonium nitrate, ammonium sulfate, urea ammonium nitrate, calcium nitrate, magnesium nitrate, and organic nitrogen derived from plants, animals or fish, such as protein hydrolysates, fish emulsion or corn steep liquor.

[0023] In other embodiments, plant nutrition compounds may include sources of macro, secondary or vegetable micronutrients.

[0024] Exemplary plant micronutrients containing potassium include, but are not limited to, potassium thiosulfate, potassium chloride, potassium nitrate, potassium sulfate, potassium and magnesium sulfate.

[0025] Exemplary phosphorus-containing plant micronutrients include, but are not limited to, monopotassium phosphate, dipotassium phosphate, monopotassium phosphate, dipotassium phosphate, calcium phosphate, tetrapotassium pyrophosphate, ammonium polyphosphate, sodium tripolyphosphate, phosphoric acid and acid phosphorous.

[0026] Examples of sulfur-containing plant micronutrients include, but are not limited to, calcium sulfate, magnesium sulfate, calcium thiosulfate, magnesium thiosulfate, potassium thiosulfate, ammonium thiosulfate, potassium sulfate and monopotassium sulfate.

[0027] Still other exemplary plant micronutrients include, but are not limited to, iron sulfate, manganese sulfate, copper sulfate, zinc sulfate, boric acid, sodium molybdate, ammonium molybdate, ferric chloride, zinc chloride, nitrate of zinc, as well as chelates (i.e. chelated forms).

[0028] Exemplary plant growth modifiers or regulators include, but are not limited to, auxins and cytokinins in synthetic form or naturally derived form, such as seaweed or seaweed extracts.

[0029] Exemplary beneficial plant microbes include, but are not limited to, Bacillus spp, Paenobacillus spp, Brevibacillus spp, Metarhizium spp, Trichoderma spp, Glomus spp, Vesicular arbuscular mycorrhizae, Rhizobium spp, Bradyrhizobium, Paecilomyces spp and Beauveria spp.

[0030] Exemplary soil conditioners and/or plant biostimulants include, but are not limited to, humic and fulvic acids, which may be in the form of liquid potassium humate (Supa Humus 26, Agrichem), liquid potassium fulvate ( Supa Fulvic 6, Agrichem), potassium humate powder/flake or crystalline and potassium fulvate powder/flake or crystalline. Humics and fulvics may be derived from peat, leonardite, or brown lining. In addition to humic and fulvic acids, ammonium ligninsulfonate, potassium ligninsulfonate and sodium lignosulfonate, such as, but not limited to, Marasperse AG and Borregado HA-1 powder (Borregaard Lignotech) can also be used. Useful.

Finishing techniques and procedures

[0031] In one or more embodiments, the aqueous dipotassium calcium pyrophosphate dispersion may be subjected to one or more finishing procedures before storage, transportation and/or use. For example, in one or more embodiments, the aqueous dispersions may be subjected to filtration to remove processing residues or raw material impurities released from the raw materials during the course of the synthesis. This may include filtration of the aqueous dispersion through a filter bag of 100 micron to 1 micron mesh or felt fabric, although the skilled artisan may choose finer filtration materials to obtain smaller particle sizes.

Features of aqueous dispersion

[0032] As indicated above, the methods described herein are believed to produce an aqueous dispersion of dipotassium calcium pyrophosphate. This dispersion may be characterized by one or more advantageous characteristics.

[0033] In one or more embodiments, the aqueous dispersion of dipotassium calcium pyrophosphate is characterized by a pH of at least 6.0, in other embodiments at least 7.0, in other embodiments at least 8.0, in other embodiments at least 8.5, and in other modalities at least 8.7. In these or other modalities, the dipotassium calcium pyrophosphate dispersion is characterized by a pH of maximum 14, in other modalities maximum 12, in other modalities maximum 10, in other modalities maximum 9.5, and in other modalities maximum 9.0. In one or more embodiments, the aqueous dipotassium calcium pyrophosphate dispersion is characterized by a pH of about 6.0 to about 14, in other embodiments of about 7.0 to about 12, in other embodiments of from about 8.0 to about 10 and in other embodiments from about 8.5 to about 9.5. The choice of target pH may depend on the final application of the formulation and/or the choice of optional agrochemicals that can be added to the composition.

[0034] In one or more embodiments, the aqueous dispersion of dipotassium calcium pyrophosphate is characterized by an advantageous particle size. In one or more embodiments, the particles within the dispersion may be quantitatively characterized by a distribution in which at least 90%, in other embodiments at least 95%, and in other embodiments at least 99% of the particles dispersed in the aqueous dispersion are particle size less than 1 micron. In one or more embodiments, at least 90%, in other embodiments at least 95%, and in other embodiments at least 99% of the dispersed particles have an average particle size of 0.1 to 0.5 or 0.2 to 0, 4 microns. In one or more embodiments, the aqueous dispersions of this invention are characterized by colloidal dispersion dispersions, which the skilled artisan recognizes as said dispersions in which the average particle size of the dispersed particles is less than 1.0 microns and generally in the range of about 0.1 to about 1.0 microns. In these or other embodiments, the particles within the dispersion may be quantitatively characterized by a D50 of less than or equal to 20 µm, in other embodiments less than 10 µm, in other embodiments less than 5 µm, in other embodiments less than 3 µm, and in other embodiments less than 3 µm. other embodiments less than 1 µm (i.e., 50% of the particles have a diameter that is equal to or less than the specified length). In these or other embodiments, particles within the dispersion may be quantitatively characterized by a D90 of less than or equal to 50 µm, in other embodiments less than 25 µm, in other embodiments less than 12 µm, in other embodiments less than 5 µm, in other embodiments less than 3 µm and in other embodiments less than 1 µm (i.e., 90% of the particles have a diameter that is equal to or less than the specified length).

[0035] In one or more embodiments, the dipotassium calcium pyrophosphate particles can be characterized by a platelet or sheet shape. These platelet particles can be characterized by having at least one dimension that is less than 1, in other embodiments less than 0.5, in other embodiments less than 0.3, in other embodiments less than 1.5, and in other embodiments less to 1.0 micron. Other forms of particles can also be employed. In one or more embodiments, these other shapes, such as needles or cubes, may have a contact surface area (i.e., the surface of the particle that contacts the substrate, such as a leaf of a plant) relative to the surface total particle greater than 1:6, in other modalities greater than 1:4, in other modalities greater than 1:3 and in other modalities greater than 1:2.5.

[0036] In one or more embodiments, the aqueous dispersion of dipotassium calcium pyrophosphate is characterized by a Brookfield viscosity (measured using Brookfield RVT, spindle 3, at 25 ° C and 50 rpm) of at least 0.9 (900), in other modalities at least 1.0 (1,000), in other modalities at least 1.2 (1,200) and in other modalities at least 1.5 (1,500) Pa.s (cps). In these or other embodiments, the aqueous dipotassium calcium pyrophosphate dispersion is characterized by a Brookfield viscosity of less than 5.0 (5,000), in other embodiments less than 3.0 (3,000), in other embodiments less than 2.7 (2,700) and in other modalities less than 2.5 (2,500) Pa.s (cps). In one or more embodiments, the aqueous dipotassium calcium pyrophosphate dispersion is characterized by a Brookfield viscosity of about 0.9 (900) to about 5.0 (5,000), in other embodiments of about 1.0 (1,000). ) to about 3.0 (3,000) in other embodiments from about 1.2 (1,200) to about 2.7 (2,700) and in other embodiments from about 1.5 (1,500) to about 2.5 (2,500) Pa.s (cps).

[0037] In one or more embodiments, the dispersion prepared according to this invention includes a mixture of suspended solids and also dissolved solids. Solids content can be varied based on the addition of plant nutrition compounds or plant growth regulators. In one or more embodiments, the total solids content varies between 40% w/w and 60% w/w, or in other embodiments between 45% w/w and 55% w/w. In one or more embodiments, the sub-micron suspended solids content may vary from 15% w/w to 25% w/w, or in other embodiments approximately 18% w/w to 22% w/w.

[0038] In one or more embodiments, the aqueous dispersion of dipotassium calcium pyrophosphate is characterized by an advantageous shelf life, which can be defined according to the CIPAC method: MT 46 Accelerated Storage Tests by Heating or APVMA, December 2005, Guidelines for Generating Storage Stability Data for Agricultural Chemicals. In one or more embodiments, the validity period may be at least 12 months, in other embodiments at least 18 months, and in other embodiments at least 24 months.

[0039] In one or more embodiments, aqueous dispersions of dipotassium calcium pyrophosphate prepared according to the present invention can be characterized by an advantageous zeta potential, which can be determined by microelectrophoresis and/or electrophoretic light scattering. In one or more embodiments, the zeta potential is greater than +30, in other embodiments greater than +35, in other embodiments greater than +40, and in other embodiments greater than +45 milliVolts at a pH of 7 +/- 1. In In other embodiments, the zeta potential is less than -30, in other embodiments less than -35, in other embodiments greater than -40, and in other embodiments less than -45 milliVolts at a pH of about 6.0 to about 14, in other embodiments from about 7.0 to about 12, in other embodiments from about 8.0 to about 10, and in other embodiments from about 8.5 to about 9.5.

[0040] In one or more embodiments, aqueous dispersions of dipotassium calcium pyrophosphate prepared in accordance with the present invention can be characterized by a refractive index of about 1.3 to about 1.9, in other embodiments of 1 .4 to 1.8 and embodiments of about 1.4 to about 1.7.

Use as liquid fertilizer

[0041] As indicated above, the aqueous dispersions of dipotassium calcium pyrophosphate produced in accordance with the present invention can advantageously be used as a liquid fertilizer. These liquid fertilizers can advantageously be applied as free-flowing liquids directly to plant life through foliar application. In other embodiments, these liquid fertilizers can be applied to soils, such as, but not limited to, sands, silts and clays. In still other embodiments, these liquid fertilizers can be added directly to nutrient solutions employed in soilless cultivation systems, such as, but not limited to, hydroponics, nutrient film techniques, and fertigation/irrigation systems employing media, such as such as coca peat, coconut and rockwool. In still other embodiments, these dispersions can be applied directly to seeds (i.e., seed coating, seed curing, and seed treatment). In still other embodiments, the dispersions of this invention can be used to coat and/or impregnate solid fertilizer granules and particles, such as, but not limited to, diammonium phosphate, monoammonium phosphate, monopotassium phosphate and urea. In other embodiments, the dispersions of this invention can be dispersed in other fertilizers during their production; for example, they can be dispersed in molten urea (such as urea lava at 150 °C) and then cooled. Advantageously, a wide range of fillers is possible when combining the dispersion of this invention with the manufacture of the commodity fertilizer and/or after adding the dispersion as a surface coating for commodity fertilizers.

[0042] In one or more embodiments, while aqueous dispersions of dipotassium calcium pyrophosphate, as described above, can be reasonably concentrated, which can facilitate transportation and storage, these aqueous dispersions can be diluted before use in the field. For example, those skilled in the art will be able to make and use diluted compositions based on desired utilization rates for dipotassic calcium pyrophosphate and/or supplemental fertilizers, such as a nitrogen source.

[0043] The dispersions prepared in one or more embodiments of this invention are advantageously compatible with other agrochemicals in aqueous solutions. For example, aqueous dispersions of dipotassium calcium pyrophosphate can be combined with concentrated (including saturated) solutions of, for example, diammonium phosphate, monoammonium phosphate and urea, maintaining the dispersion of the dipotassium calcium pyrophosphate and the solubility of the chemical. supplementary (e.g. diammonium phosphate). Furthermore, these compatible liquid fertilizer systems can be prepared without the use of chelates. Additionally, these liquid fertilizer systems, which include compatible mixtures of insoluble dipotassium calcium pyrophosphate with concentrated solutions of agrochemicals, are advantageously stable for extended periods, such as at least 1 day, in other embodiments at least 3 days, in other embodiments at least 1 week.

[0044] Aqueous dispersions of calciumdipotassium pyrophosphate, or diluted compositions thereof, can be applied to a plant using a variety of techniques. In one or more embodiments, spraying techniques are employed. In other embodiments, the liquid fertilizer produced in accordance with the present invention can be applied to the plant through the soil. Known techniques include saturating or soaking the surrounding soil with the aqueous dispersion. Specific application methods may employ a spray bar, a hand sprayer, low volume applicators, high and low volume field mounted equipment, aerial sprayers, controlled droplet applicators, CDA equipment and/or combinations thereof.

[0045] The liquid fertilizers of this invention can be advantageously applied to a variety of agricultural crops. And the dipotassium calcium pyrophosphates prepared according to this invention have been found to have several agricultural benefits. For example, dipotassium calcium pyrophosphates prepared in accordance with embodiments of this invention are believed to increase the mobility and translocation of nutrients (e.g., potassium, calcium, and phosphorus) within the soil. Additionally, dipotassium calcium pyrophosphates are believed to contribute to prolonged nutrient availability to the plant, and protect nutrients from chemical and soil adhesion.

[0046] In order to demonstrate the practice of the present invention, the following examples were prepared and tested. The examples should not, however, be seen as limiting the scope of the invention. The claims will serve to define the invention.

EXPERIMENTAL SECTION Example 1

[0047] To a two-liter polypropylene measuring cup, 320 grams of water and 575 grams of tetrapotassium pyrophosphate (96.0% minimum purity) were added to form a tetrapotassium pyrophosphate solution (TKPP solution). The beaker was stirred using an IKA Rw20n bench top mixer mounted with 40 cm length and 4 5 cm stainless steel paddles at 1700 rpm. It was noted that the pH was 12.1.

[0048] In a separate one-liter graduated polypropylene beaker, 340 grams of water and 125 grams of anhydrous calcium acetate (98.0% minimum purity) were added to form a calcium acetate solution. The second beaker was stirred until the solids were completely dissolved, forming a clear, colorless solution. It was noted that the pH was 9.2.

[0049] The dissolved calcium acetate was loaded into the beaker with the TKPP solution over a period of 2 minutes to produce insoluble potassium and calcium pyrophosphate particles. The temperature of the mixture was 48 °C at the end of the addition of calcium acetate. Mixing continued at 1700 rpm for 60 minutes as 30 grams of glacial acetic acid was slowly charged over a period of one minute. Mixing continued for a further 6 hours at 1700 rpm, as 50 g of hydrated gum base was added to the mixture, followed by 0.5 g of defoamer. Mixing continued at 1700 rpm for one hour. Water was then added to form a one liter mixture.

[0050] The ingredients used in this example are summarized in the Table. Physical and chemical tests were carried out, and the results are also provided in the Table. Specific gravity was conducted using a DMA35 Density Meter at 25°C, pH was determined at 25°C, viscosity was determined using a Brookfield RVT spindle 3 viscometer at 25°C, particle size was determined using a Malvern Mastersizer 2000, the elemental content was determined using an inductively coupled plasma optical emission spectrometer, and the insoluble content was determined using a gravimetric method (involving sample dilution, solids sedimentation and drying of the solids). Table

[0051] This example shows at least some of the benefits of the present invention in that the dispersion has, among other beneficial properties, an advantageous viscosity and particle size.

Example 2

[0052] A dispersion was prepared using the same general procedure presented in Example 1, except that the amount of reagents was reduced (by 10%), and optional pesticides were included. In this case, 89 grams of Supa Zinc (Agrichem LTD) were added. Supa Zinc contains 5.9% w/w zinc present as zinc dipotassium salt EDTA. The ingredients used in this example are summarized in the table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0053] This example illustrates that other fertilizer ingredients can be easily incorporated into the composition. Furthermore, the composition was modified by reducing the amount of potassium and calcium pyrophosphate to allow the incorporation of 0.3% w/w zinc. This example also illustrates that advantageous dispersions can be obtained with changes in the amount of base ingredients while maintaining appropriate molar ratios.

Example 3

[0054] A dispersion was prepared using the same general procedure presented in Example 1, except that calcium thiosulfate was used instead of calcium acetate. The ingredients used in this example are summarized in the Table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0055] This example demonstrates that other water-soluble calcium salts can be replaced with calcium acetate to obtain a similar result.

Example 4

[0056] A dispersion was prepared using the same general procedure set out in Example 1, except that the ratio of calcium to phosphorus was reduced from 1:4.2 to 1:2.2. The ingredients used in this example are summarized in the Table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0057] This example demonstrates the ability to change particle size based on the ratio of phosphorus to calcium. Namely, an increase in the amount of calcium relative to phosphorus will result in an increase in particle size.

Example 5

[0058] A dispersion was prepared using the same general procedure described in Example 1, with the exception of using both calcium acetate and calcium thiosulfate as the soluble calcium salt. The ingredients used in this example are summarized in the Table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0059] This example demonstrates the ability to employ a mixture of different water-soluble calcium salts, which advantageously allows the optimization of the mixture of nutrients in the formulation and/or the final cost of the formulation.

Example 6

[0060] A dispersion was prepared using the same general procedure described in Example 1, with the exception that the calcium acetate was replaced by a molar equivalent amount of magnesium acetate tetrahydrate. The ingredients used in this example are summarized in the table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0061] The use of a water-soluble magnesium salt in place of a water-soluble calcium salt gave a much lower viscosity and a much coarser dispersion. These characteristics suggest that this composition would not be useful for its intended purpose because the composition would have an unacceptable shelf life. Therefore, this example demonstrates the advantages of employing calcium as the cation, especially with regard to generating a self-stabilizing viscosity for the final mixture and producing advantageous particle sizes.

Example 7

[0062] A dispersion was prepared using the same general procedure described in Example 1, with the exception that the tetrapotassium pyrophosphate was replaced by potassium tripolyphosphate keeping the phosphorus to calcium ratio identical to Example 1. The ingredients used in this Example are summarized in the table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0063] Although the molar ratio of calcium to phosphorus was kept similar to Example 1, the use of a tripolyphosphate instead of a pyrophosphate resulted in extremely high viscosity. The resulting mixture was a non-flowing liquid, but rather a semi-solid paste. These characteristics suggest that this composition would not be useful for its intended purpose. Therefore, this example demonstrates the advantages of using pyrophosphate to generate fine-sized particles within a fluid aqueous dispersion of calcium and potassium polyphosphate.

Example 8

[0064] A dispersion was prepared using the same general procedure described in Example 1, with the exception that the calcium acetate was replaced by an equivalent molar amount of manganese sulfate monohydrate. The ingredients used in this example are summarized in the table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0065] Although the molar ratio of metal cation to phosphorus was kept similar to Example 1, the use of a water-soluble manganese salt in place of a calcium salt gave a very low viscosity and an unacceptable particle size. The pure mixture quickly segregated into a clear liquid layer arranged on a moist cake or solids layer. These characteristics suggest that this composition would not be useful for its intended purpose because the composition would have an unacceptable shelf life. Therefore, this example demonstrates the advantages of employing calcium as the cation, especially with regard to generating a self-stabilizing viscosity for the final mixture and producing advantageous particle sizes.

Example 9

[0066] A dispersion was prepared using the same general procedure presented in Example 1, with the difference that the calcium acetate was replaced by a molar equivalent of calcium nitrate tetrahydrate. The ingredients used in this example are summarized in the table. Physical and chemical tests were also carried out and the results are presented in the Table.

[0067] As in Example 3 above, this example demonstrates that other water-soluble calcium salts can be replaced by calcium acetate. Some distinctions, however, were noted that could affect the ultimate use of the product for its intended use. For example, while the viscosity that developed was adequate to self-stabilize the formulation, the particle size remained slightly coarser than that achieved using calcium acetate. Furthermore, the dispersion was not completely cold stable, as potassium nitrate crystals formed at temperatures below 10 °C. This suggests that for calcium nitrate to be used, a more diluted version would be needed than that required for calcium acetate (Example 1) and calcium thiosulfate (Example 3).

[0068] Various modifications and alterations which do not depart from the scope and spirit of this invention will become apparent to persons skilled in the art. This invention should not be duly limited to the illustrative embodiments set forth herein.

Claims (14)

1. Aqueous dispersion characterized by: i. water; and ii. calcium and potassium polyphosphate dispersed in water, wherein said dispersion is defined by a Brookfield viscosity (Brookfield RVT, spindle #3, 25°C, 20 rpm) of 1500 to 3000 Pa.s (cps), wherein said dispersion is defined by a particle size distribution wherein at least 90% of the particles within the dispersion have a particle size of less than 1 micron, and wherein said aqueous dispersion includes from 15% to 25% w/w of particles suspended with a particle size of less than 1 micron. 2. Aqueous dispersion according to claim 1, characterized by the fact that the calcium potassium polyphosphate is dipotassium calcium pyrophosphate. 3. Aqueous dispersion according to claim 1 or 2, characterized by the fact that it additionally comprises a nutritional compound for plants, a plant growth regulator or a beneficial microbe for plants. 4. Aqueous dispersion according to any one of claims 1 to 3, characterized by the fact that said dispersion is defined by a pH of 8.0 to 9.5; wherein said dispersion is defined by a total solids content of 40% to 60% and suspended solids content of 18% to 22%; and wherein said dispersion is defined by a shelf life, as determined by the CIPAC method: MT 46 Accelerated Storage Tests by Heating of at least 12 months. 5. Aqueous dispersion according to any one of claims 1 to 4, characterized by the fact that said calcium and potassium polyphosphate is calcium dipotassium pyrophosphate, wherein said calcium dipotassium pyrophosphate is substantially insoluble in water. 6. Aqueous dispersion according to any one of claims 1 to 5, characterized by the fact that said dispersion is defined by a pH of at least 6.0. 7. Method for preparing an aqueous dispersion as defined in claim 1, the method characterized by comprising the steps of: i. provide a solution of tetrapotassium pyrophosphate; and ii. introducing a water-soluble calcium salt to the aqueous solution of tetrapotassium pyrophosphate to form the fluid liquid fertilizer in the form of an aqueous dispersion of calcium potassium polyphosphate, said dispersion being defined by a Brookfield viscosity (Brookfield RVT, spindle #3, 25°C, 20 rpm) from 1500 to 3000 Pa.s (cps), wherein said dispersion is defined by a particle size distribution, wherein at least 90% of the particles within the dispersion have a size of particle size less than 1 micron, and wherein said aqueous dispersion includes from 15% to 25% w/w of suspended particles having a particle size of less than 1 micron. 8. Method according to claim 7, characterized by the fact that the calcium and potassium polyphosphate is dipotassium calcium pyrophosphate. 9. Method according to claim 7 or 8, characterized by the fact that it additionally includes the step of introducing a plant nutrition compound or a plant growth regulator. 10. Method according to any one of claims 7 to 9, characterized by the fact that said tetrapotassium pyrophosphate solution includes between 200 and 250 parts by weight of tetrapotassium pyrophosphate per 100 parts by weight of water; and wherein said step of introducing a water-soluble calcium salt into the tetrapotassium pyrophosphate solution provides a mixture wherein the molar ratio of moles of calcium within the water-soluble calcium salt to moles of phosphorus within the tetrapotassium pyrophosphate is 1:3 to 1:5. 11. Method according to any one of claims 7 to 10, characterized by the fact that said tetrapotassium pyrophosphate solution includes between 200 and 250 parts by weight of tetrapotassium pyrophosphate per 100 parts by weight of water; and said step of introducing a water-soluble calcium salt into the tetrapotassium pyrophosphate solution provides a mixture, wherein the molar ratio of moles of calcium within the water-soluble calcium salt to moles of phosphorus within the tetrapotassium pyrophosphate is 1 :1 to 1:7. 12. Method according to any one of claims 7 to 11, characterized by the fact that the water-soluble calcium salt is selected from the group consisting of calcium acetate, calcium thiosulfate, calcium formate, calcium nitrate, chloride of calcium and mixtures of two or more thereof. 13. Method according to any one of claims 7 to 12, characterized by the fact that the water-soluble calcium salt is calcium acetate; or calcium salt is calcium thiosulfate. 14. Method of applying aqueous dispersion as plant fertilizer characterized by comprising the steps of: i. providing an aqueous dispersion of potassium calcium polyphosphate as defined in claim 1; and ii. apply the aqueous dispersion of calcium and potassium polyphosphate to the plant, wherein said dispersion is defined by a Brookfield viscosity (Brookfield RVT, spindle #3, 25°C, 20 rpm) of 1500 to 3000 Pa.s (cps), wherein said dispersion is defined by a particle size distribution, wherein at least 90% of the particles within the dispersion have a particle size of less than 1 micron, and wherein said aqueous dispersion includes from 15% to 25% w/w of suspended particles having a particle size of less than 1 micron.