Iron-containing fertilizer granules

Abstract

The present invention relates to the field of fertilizer granules. More specifically, it relates to a fertilizer granule comprising a fertilizer core and an outer layer of a regulator, the regulator comprising an iron chelate component dissolved in a solvent, wherein the solvent is selected from the group consisting of glycols, glycol ethers and mixtures thereof, the iron chelate component, and optionally urea. The present disclosure also relates to a method for preparing such fertilizer granules. In another aspect, the present disclosure relates to a liquid composition comprising an iron chelate component dissolved in a solvent and urea, the solvent being selected from the group consisting of glycols, glycol ethers and mixtures thereof. Finally, it also relates to the use of the liquid composition as a coating agent for solid fertilizer granules, the liquid composition comprising an iron chelate component dissolved in a solvent selected from the group consisting of glycols, glycol ethers and mixtures thereof, and optionally urea.

Description

[0001] This application is a divisional application of the patent application for "ferrous fertilizer granules" with the application date of May 6, 2020, the application number of 202080026078.4, and the invention title. Technical Field

[0002] The present disclosure relates to the field of fertilizer granules, particularly fertilizer granules coated with an iron-containing composition. Background Art

[0003] Iron (Fe) is a micronutrient required for the optimal growth of all plants and crops. It plays a role in numerous biological processes, such as the reduction of nitrates and sulfates, energy production, chlorophyll synthesis, and lignin formation. Although iron is present in most soils, additional iron sources are often required for crops to meet all crop demands.

[0004] Iron deficiency is a common micronutrient disorder in many crops, especially those grown in calcareous and high pH soil areas. Generally, soil application of inorganic iron sources (such as ferrous sulfate) is ineffective in treating this micronutrient deficiency because, under these soil conditions, iron rapidly converts to an unavailable, insoluble form, such as iron oxide. Therefore, the use of chelated forms of iron is a common agricultural practice. Iron chelates contain Fe as a trivalent iron (Fe 3+ ) or ferrous (Fe 2+ ) cation and a ligand. The ligand is typically an organic molecule that is soluble in a variety of organic solvents and water. The resulting ligand-metal complex exhibits high solubility in oxygen-containing solvents (such as water, alcohols, or ethers). Ethylenediaminetetraacetate (EDTA) is a well-known ligand that has a high affinity for most transition metals, including iron. Ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) and ethylenediamine-N-[(2-hydroxyphenyl)acetic acid]-N'-[(4-hydroxyphenyl)acetic acid] are other ligands suitable for forming chelates with iron for use as fertilizers. Commercially available products typically contain a mixture of the above ortho-ortho (o-o) and ortho-para (o-p) isomers, collectively referred to as FeEDDHA. Other effective iron chelates are iron chelate ethylenediamine-N,N'-di[2-hydroxy-methylphenyl]acetic acid] and ethylenediamine-N-[2-hydroxy-methylphenyl]acetic acid]-N'-[(4-hydroxy-methylphenyl)acetic acid]. Commercially available products may contain a mixture of the above ortho-ortho and ortho-para isomers, collectively referred to as FeEDDHMA. Another effective iron chelate is iron chelate N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, commonly referred to as FeHBED.

[0005] Typically, FeEDDHA, FeEDDHMA, and FeHBED chelates are provided in powder, granular, or particulate form, and it is common practice to apply them directly to the soil or dissolve them in irrigation water prior to application to the soil.

[0006] However, in addition to the above application methods, iron and other micronutrients can be incorporated into solid fertilizers, such as pellets or granules containing one or more primary nutrients (nitrogen - N, phosphorus - P, and potassium - K), and applied by spreading on the soil. It is often necessary to add micronutrients, including iron, to these mainstream solid fertilizers to meet the agronomic requirements of crops. This can be achieved by adding micronutrients during the pelleting or granulation process, but practical considerations in large - scale production operations mean that it is difficult to meet the widely different nutritional requirements of different crops and different soil types using this method.

[0007] For micronutrients, adding a nutrient source to the coating of fertilizer granules is a well - known method. Several types of granules containing one or several primary nutrients (N, P, K) require the application of a coating composition to increase the durability of such granules, so adding a micronutrient source to the coating composition is an effective way to solve both problems. In the coating composition, the micronutrient source is dissolved or suspended in the liquid phase.

[0008] For example, GB25132232 (Yara, 2014) discloses a method for preparing a fertilizer coated with an oil - based composition containing a micronutrient source. However, attempts to prepare oil - based suspensions of FeEDDHA, FeEDDHMA, and FeHBED have proven unsuccessful. For example, the preparation of a composition consisting of FeEDDHA or FeHBED suspended in various oils (including rapeseed oil, methylated seed oil, or light mineral oil) using the method described in GB25132232 results in the formation of a highly viscous sticky mass, even when the iron concentration is as low as 2% by weight. Such a composition is extremely difficult to handle and cannot be easily used as a fertilizer coating.

[0009] EP0334630 (PHOSYN, 1989) discloses a composition containing iron chelates, such as FeEDDHA and FeEDDHMA, and a polyol or ether solvent, such as ethylene glycol and ethylene glycol monoethyl ether. The composition is diluted with water and applied directly to the soil to provide iron to the crops.

[0010] FR2808021 (Synthron Chemicals, 2001) discloses a liquid composition comprising a sodium or potassium salt of FeEDDHA or FeEDDHMA, a dispersant and a polymeric alkylene oxide such as polyethylene glycol, polypropylene glycol and their derivatives. The composition can be diluted with water and applied to soil or as a foliar spray to treat iron chlorosis, i.e. iron deficiency.

[0011] WO03042128 (Akzo Nobel, 2003) discloses a composition comprising water, an iron chelate and an amide having the formula RCONH2 which may be urea.

[0012] CN10638008 A (Shandong Shuangwei Landscape Technology Co., Ltd., 2017) discloses an aqueous solution of an alkaline soil scale inhibitor comprising chelated iron, diethylene glycol and urea. Summary of the Invention

[0013] Surprisingly, it has now been found that compositions containing an iron chelate component dissolved in a solvent selected from glycols, glycol ethers and mixtures thereof are very suitable for fertilizer coating applications, thus providing a simple and flexible method by which solid fertilizers can be coated with an effective iron source without negatively affecting the fertilizer quality.

[0014] In a first aspect of the present invention, there is provided a fertilizer granule comprising a core and an outer layer of a conditioner, the conditioner comprising an iron chelate component dissolved in a solvent selected from the group consisting of glycols, glycol ethers and mixtures thereof, and wherein the solvent comprises from about 30 wt% to about 90 wt% of the conditioner.

[0015] In another aspect, there is provided a method of manufacturing a fertilizer granule, wherein the fertilizer granule comprises a layer of a conditioner containing iron, the method comprising the steps of: (a) providing a fertilizer granule core; (b) applying an amount of a conditioner to the fertilizer granule core, the conditioner comprising an iron chelate component dissolved in a solvent selected from the group consisting of glycols, glycol ethers and mixtures thereof, and wherein the solvent comprises from about 30 wt% to about 90 wt% of the conditioner.

[0016] In another aspect, there is provided a liquid composition comprising an iron chelate component dissolved in a solvent selected from glycols, glycol ethers and mixtures thereof and urea, wherein the liquid composition comprises at least 30 g / L of iron.

[0017] In another aspect, there is provided the use of a composition as a coating agent for fertilizer granules, the composition comprising an iron chelate component dissolved in a solvent selected from the group consisting of glycols, glycol ethers, and mixtures thereof, and optionally urea. DETAILED DESCRIPTION

[0018] Unless otherwise defined, all terms used to disclose the present invention, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains. Further guidance is provided, including term definitions, to better understand the teachings of the present invention.

[0019] All references cited in this specification are hereby incorporated by reference in their entirety.

[0020] As used herein, the following terms have the following meanings:

[0021] Unless the context clearly dictates otherwise, as used herein, "a", "an", and "the" refer to both the singular and plural referents. For example, "a compartment" refers to one or more than one compartment.

[0022] As used herein, "about" refers to a measurable value, such as a parameter, quantity, duration, etc., and is intended to include variations of + / - 20% or less, preferably + / - 10% or less, more preferably + / - 5% or less, even more preferably + / - 1% or less, and still more preferably + / - 0.1% or less from the specified value, insofar as such variations are suitable for the disclosed invention. However, it should be understood that the value itself to which the modifier "about" refers is also specifically disclosed.

[0023] As used herein, "comprising", "comprises", and "comprised of" and "including" are synonymous with "includes", "includes", "includes" or "contains", "contains", "contains", and are inclusive or open-ended terms used to specify the presence of the following, such as components, and do not exclude or preclude the presence of additional, unenumerated components, features, elements, members, steps known in the art or disclosed therein.

[0024] Reference to a numerical range by endpoints includes all numbers and fractions contained within that range, as well as the recited endpoints.

[0025] Unless otherwise defined, the expressions "% weight", "weight percentage", "% w / w", "wt%", or "% wt" herein and throughout the specification refer to the relative weight of each component based on the total weight of the formulation.

[0026] In a first aspect of the present invention, there is provided a fertilizer granule, said granule comprising a core and an outer layer of a conditioner, said conditioner comprising an iron chelate component dissolved in a solvent, and the main feature is that said solvent is selected from the group consisting of glycols, glycol ethers and mixtures thereof, and accounts for about 30 to about 90% by weight of the conditioner.

[0027] It has been found that fertilizer granules containing a large amount of iron chelate can be prepared by coating a fertilizer core containing nutrients with a conditioner containing an iron chelate component dissolved in a solvent. From EP0334630, it is known that solvents selected from glycols and glycol ethers, such as monoethylene glycol, diethylene glycol and ethylene glycol monoethyl ether, can be used to obtain a liquid composition containing a high concentration of iron chelate (iron content higher than 3 wt%). It has been found that these compositions can be applied to solid fertilizer cores to provide a fertilizer composition containing a suitable iron source. The solvent can be of high purity, especially it can be at least 98% pure, more especially at least 99% pure. The conditioner should comprise about 30 to about 90% by weight of the solvent to be suitable for coating on the solid fertilizer core. The solvent can be a single chemical component, but can also be a mixture of two or more glycols or glycol ethers.

[0028] The amount of solvent that may be used may depend on the iron chelate selected for the conditioner and the desired iron loading. In one embodiment, the solvent may account for about 40 to about 80% by weight of the conditioner. In particular, it may account for about 40 to about 50% by weight of the conditioner. It has been found that the fertilizer granules comprising the conditioner layer are free-flowing, which is important for handling operations. In addition, the product exhibits good anti-caking properties and its crushing strength does not decrease too much compared to the uncoated product. Anti-caking and crushing strength are important parameters of fertilizer granules and affect the storability of the granules.

[0029] In one embodiment, the outer layer of the conditioner may cover at least 95% of the surface of the core, especially at least 96% of the surface, more especially at least 98% of the surface, and even more especially at least 99% of the surface. In one embodiment, the conditioner layer may cover 100% of the surface of the fertilizer granule core.

[0030] In one embodiment, the conditioner comprises urea. Surprisingly, it has also been found that adding a small amount of urea to the conditioner reduces the viscosity of such a conditioner. When applying these reagents to solid particles, such as fertilizer particles, it is desirable for the conditioner to have a viscosity that enables good and uniform coating. There are various methods for applying the conditioner to solid particles, such as: mixing in a blender, spraying the reagent. In particular, the viscosity of the conditioner at 20 °C can be in the range of about 0.005 to about 7 Pa·s (5 to 7000 cP), especially in the range of about 0.1 to about 5 Pa·s (100 to 5000 cP). If the spraying method is adopted and the viscosity is too high, the liquid is not easily sprayed and is prone to clogging the spraying equipment. In addition, due to the high viscosity, the redistribution of the resulting coating on the particles may be uneven. Since urea is a nutrient source, adding urea to the conditioner does not reduce the total nutrient content of the fertilizer particles. Urea can be added as a solid and is easily soluble in organic solvents. It can be dissolved in a small amount of solvent before mixing with the conditioner. To ensure the high quality of the final product, the coated fertilizer particles, the urea can be very pure. In particular, its purity can exceed 95%, more particularly exceed 96%, even more particularly exceed 97%, even more particularly exceed 98%, even more particularly exceed 99%. Urea can contain a small amount of water and / or biuret, especially it can contain less than 5 wt% of water or biuret, more particularly less than 2 wt% of water or biuret. In one embodiment, the conditioner contains from about 0.1 to about 5.0 wt% of urea. In particular, it can contain up to 2.0 wt% of urea.

[0031] In one embodiment, the solvent is selected from the group consisting of monoethylene glycol, monopropylene glycol, diethylene glycol, 2-(2-ethoxyethoxy)ethan-1-ol, also known as diethylene glycol monoethyl ether, and mixtures thereof. Monoethylene glycol, monopropylene glycol, diethylene glycol, and 2-(2-ethoxyethoxy)ethan-1-ol are all well-known ethylene glycol solvents and are widely used in the chemical industry. They have good tolerance to plants, although some of these substances are classified as harmful substances, such as monoethylene glycol and diethylene glycol. It has been found that 2-(2-ethoxyethoxy)ethan-1-ol is a particularly suitable solvent for preparing a liquid solution with a high concentration of iron chelate, because 2-(2-ethoxyethoxy)ethan-1-ol is classified as a non-harmful substance. It reduces the risk when operating the conditioner. In one embodiment, the solvent is 2-(2-ethoxyethoxy)ethan-1-ol. In one embodiment, the solvent is monoethylene glycol.

[0032] In one embodiment, the regulator particularly comprises 40 to 90% by weight of a solvent.

[0033] In one embodiment, the regulator contains at least 30 g / L of iron, particularly at least 35 g / L of iron, more particularly at least 40 g / L, and even more particularly at least 44 g / L of iron. Here, the specified mass per unit volume refers to the total mass of iron cations in the regulator. In order to provide a sufficiently high amount of iron to the plant, it has been found that the regulator should contain at least 30 g / L of iron. The high iron loading of the reagent allows farmers or fertilizer suppliers to use a lower loading of the regulator on the fertilizer core. This is desirable because high loading may reduce the physical properties of the final product, such as anti-caking or strength index. High coating loading may also make the product sticky and difficult to store, handle, and spread in the field. Iron is substantially present in the regulator in the form of an iron chelate component. Other iron sources, such as inorganic salts, are not desirable because they are not stable enough under typical soil conditions and quickly become unavailable to the plant.

[0034] In one embodiment, the iron chelate component is an iron chelate of a chelating agent, where the chelating agent is an amino-alcohol or an aminopolycarboxylic acid, particularly a group selected from ethylenediamine-N,N'-di[(ortho-hydroxyphenyl)acetic acid], ethylenediamine-N-[(ortho-hydroxyphenyl)acetic acid]-N'-[(para-hydroxyphenyl)acetic acid], ethylenediamine-N,N'-di[ortho-hydroxy-methylphenyl]acetic acid, ethylenediamine-N-[ortho-hydroxymethylphenyl]acetic acid]-N'-[(para-hydroxy-methylphenyl)acetic acid] or N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid and mixtures thereof. Iron chelates are commercially available as a variety of compounds. Those containing amino-alcohols or aminopolycarboxylic acids have been found to be particularly suitable for the modulators of the present invention. They are generally non-toxic to plants and have high solubility in a variety of organic solvents, including glycols and glycol ether solvents. Iron complexes from the following compounds: ethylenediamine-N,N'-di[(ortho-hydroxyphenyl)acetic acid], ethylenediamine-N-[(ortho-hydroxyphenyl)acetic acid]-N'-[(para-hydroxyphenyl)acetic acid], ethylenediamine-N,N'-di[ortho-hydroxy-methylphenyl]acetic acid], ethylenediamine-N-[ortho-hydroxymethylphenyl]acetic acid]-N'-[(para-hydroxy-methylphenyl)acetic acid] or N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, are aminopolycarboxylic acids and are known to be suitable iron sources of agricultural origin. They are each stable within a specific pH range. The chelating agent ensures that the iron cations remain in their soluble form available to plants and do not oxidize to iron oxide, which is insoluble in water and not absorbed by plants.

[0035] In one embodiment, the conditioner comprises an anti-foaming agent. One possible method of applying the conditioner to the solid particles is to spray the reagent onto the particles. The particles may be in a drum or on a bed. When spraying a composition comprising an organic compound, there is always a risk of the composition foaming. Foam occurs when air bubbles are trapped in a layer of the organic compound. To prevent this, an anti-foaming agent can be added to the composition prior to the spraying operation. A variety of anti-foaming agents are commercially available from suppliers such as Synthron. The anti-foaming agent is typically added in very small amounts, particularly in the range of 0.001 to about 1.0% by weight relative to the total composition, and does not affect the properties of the composition other than the foaming tendency.

[0036] In one embodiment, the mass ratio of the iron chelate component to the solvent in the conditioner is in the range of 1:9 to 3:1, particularly in the range of 1:3 to 3:1, and more particularly in the range of 1:2 to 2:1. It is necessary to achieve a suitable ratio of the iron chelate component to the solvent. If the ratio is too high, the chelate may not dissolve completely in the solvent or the viscosity of the composition may become too high. This creates a problem in applying the conditioner to the fertilizer particles. If the ratio is too low, the concentration of iron will be very low. To supply sufficient iron to the plants, more conditioner needs to be applied to the fertilizer particles, which may reduce the physical properties of the particles, or a higher application rate of the particles is required, which increases the operating costs of the farmer. In addition, other nutrients contained in the particles may be supplied to the crop in excessive amounts, which may have a negative impact on the environment. For example, if too much nitrate or phosphate is provided to the soil, these ions will not be properly retained by the soil and will leach into the environment. It has been found that the mass ratio of the iron chelate component to the solvent in the conditioner can be in the range of 1:9 to 3:1, particularly in the range of 1:3 to 3:1, and more particularly in the range of 1:2 to 2:1.

[0037] In one embodiment, the conditioner is substantially anhydrous. It is desirable for the conditioner to be substantially free of water because water can reduce the physical properties of the fertilizer particles, such as particle strength and anti-caking characteristics. It may be difficult to obtain a completely anhydrous conditioner, but the conditioner can contain less than 5 wt% water, particularly less than 2 wt%, more particularly less than 1 wt%, and even more particularly less than 0.5 wt%. The components of the conditioner, solvent, iron chelate, and optionally urea can each contain a small amount of water, such as less than 5 wt% water. In particular, they can each contain less than 2 wt% water, more particularly less than 1 wt% water.

[0038] In one embodiment, the regulator accounts for 0.1 to 2.0% by weight of the fertilizer granules, particularly 0.1 to 1.0% by weight. It is important that the regulator is included in the fertilizer granules in a suitable amount. If the composition contains too little regulator, the amount of iron supplied to the crop will be insufficient to obtain optimal yields. But if it contains too much, the total nutrient content of the composition will be reduced: neither the solvent nor the ligand delivers nutrients to the plant. In addition, the physical properties of the fertilizer granules, such as granule strength, stickiness, may be reduced due to the large amount of solvent.

[0039] In one embodiment, the fertilizer core comprises at least one component selected from the group consisting of urea, ammonium salts, nitrates, phosphates, potassium salts, calcium nitrate, and mixtures thereof. It is desirable that the fertilizer core contains a high percentage of plant-available nutrients. Urea, ammonium salts, and nitrates are three sources of plant nitrogen; phosphates are the main source of plant phosphorus; other cations, such as potassium and calcium, are also important nutrients for plants. In one embodiment, the fertilizer core comprises urea. In one embodiment, the fertilizer contains all three primary nutrients N, P, and K. Such a fertilizer is called an NPK fertilizer. In addition to the primary nutrients, the fertilizer core may contain at least one source of one or more of the secondary nutrients (calcium, sulfur, magnesium) and micronutrients (boron, manganese, molybdenum, copper, and zinc). Suitable sources of these elements for agricultural use are well known in the art.

[0040] In one embodiment, the regulator contains about 0.1 to about 10% by weight of urea relative to the weight of the composition. It has been found that, relative to the total composition of the regulator, the regulator preferably contains between about 0.1 and about 10% by weight of urea. If too little urea is used, the effect of reducing viscosity is insufficient to provide a suitable composition. If too much urea is used, the iron content will be reduced and become too low for agricultural use. In particular, relative to the weight of the composition, the regulator may contain about 0.1 to about 5.0% by weight of urea. More particularly, the regulator contains about 0.1 to about 3.0% by weight of urea.

[0041] In one embodiment, the regulator contains about 35 to about 55 wt% of FeEDDHA, about 40 to about 60 wt% of monoethylene glycol, optionally 0.01 to about 1.0 wt% of an antifoaming agent, and optionally 0.1 to about 5.0 wt% of urea.

[0042] In one embodiment, the regulator contains about 35 to about 60 wt% of FeEDDHA, about 35 to about 60 wt% of diethylene glycol monoethyl ether, optionally 0.01 to about 1.0 wt% of an antifoaming agent, and optionally 0.1 to about 5.0 wt% urea.

[0043] In one embodiment, the conditioner comprises about 5 to about 25 wt% of FeHBED, about 70 to about 90 wt% of monoethylene glycol, optionally 0.01 to about 1.0 wt% of an antifoaming agent, and optionally 0.1 to 5.0 wt% of urea.

[0044] In one embodiment, the conditioner comprises about 35 to about 55 wt% of FeEDDHA, about 40 to about 60 wt% of diethylene glycol, optionally 0.01 to about 1.0 wt% of an antifoaming agent, and optionally 0.1 to about 5.0 wt% of urea.

[0045] In one embodiment, the conditioner comprises an acid. In particular, the acid can be organic, i.e., a small molecule. More particularly, the acid can be a polycarboxylic acid, and even more particularly it can be selected from citric acid, malic acid, and mixtures thereof.

[0046] When the conditioner is applied to fertilizer granules containing an ammonium source such as calcium ammonium nitrate, it is noted that the granules emit a strong and unpleasant odor. After analysis by a Drager tube, the odor was determined to be ammonia. Without being bound by theory, it is hypothesized that elements in the conditioner, such as the solvent or the iron chelate component, can exhibit basic characteristics and catalyze the conversion of ammonium to ammonia. It has been found that adding a component with acidic characteristics to the conditioner can reduce this problem. Suitable acids need to meet several criteria: acidic enough to prevent ammonia emissions, but not react or interact with the fertilizer granules and / or other elements of the conditioner; preferably soluble in the solvent or solvent mixture used in the conditioner; preferably having low health and safety risks to avoid complicating the use of the conditioner; available on the market at a reasonable price; preferably obtained in pure form or in an anhydrous solvent, however, it can be obtained as a hydrate complex. It has been found that malic acid and citric acid are two chemicals that meet these criteria and are suitable for addition to the conditioner. Malic acid is a dicarboxylic acid with pKas of 3.4 and 5.2, and citric acid is a tricarboxylic acid with pKas of 3.1, 4.8, and 6.4. It may be advantageous to reduce the pH of the conditioner to about 7 or lower to reduce ammonia emissions from the fertilizer granules. A conditioner in which citric acid is added to adjust the pH to about 7 shows a reduction of about 50% in ammonia emissions compared to the same conditioner without citric acid and with a pH of 8.7. The pH of the conditioner can be maintained above 5. Below pH = 5, the stability of the iron chelate may be affected and the iron atoms may precipitate, making them unavailable to plants. The conditioner can comprise about 0.5 to about 10% by weight of the acid. In particular, it can comprise about 0.5 to about 5% by weight of the acid, and more particularly about 1 to about 5% by weight of the acid. In one embodiment, the pH of the conditioner can be between 5.0 and 7.0.

[0047] In one embodiment, the conditioner comprises about 45 to about 60 wt% of FeEDDHA, about 35 to about 50 wt% of diethylene glycol, 0.01 to 1 wt% of an antifoaming agent, 0.1 to 1.0 wt% of urea, and 0.5 to 2.0% by weight of citric acid, preferably anhydrous citric acid.

[0048] In another aspect, there is provided a method of manufacturing fertilizer granules, wherein the fertilizer granules comprise an outer layer containing an iron-containing conditioner. The method comprises the steps of: (a) providing a fertilizer granule core; (b) applying an amount of the conditioner to the fertilizer granule core, the conditioner comprising an iron chelate component dissolved in a solvent selected from the group consisting of glycols, glycol ethers, and mixtures thereof, wherein the solvent accounts for about 30 to about 90 wt% of the conditioner. This aspect may exhibit the same or similar features and technical effects as the first aspect, and vice versa.

[0049] Many well-known methods can be used to coat fertilizer granule cores with a liquid composition, such as spraying the composition above the granules on a conveyor belt or mixing the composition and the granules in a rotating drum. Any coating method known in the art can be used in the present invention.

[0050] In one embodiment, the solvent is selected from the group consisting of monoethylene glycol, monopropylene glycol, diethylene glycol, 2-(2-ethoxyethoxy)ethanol, also known as diethylene glycol monoethyl ether, and mixtures thereof.

[0051] In one embodiment, the conditioner comprises at least 30 g / L of iron, particularly at least 35 g / L of iron, more particularly at least 40 g / L, and even more particularly at least 44 g / L of iron.

[0052] In one embodiment, the iron chelate component is an iron chelate of a chelating agent, wherein the chelating agent is an amino-alcohol or an amino polycarboxylic acid, particularly the chelating agent is selected from the group consisting of ethylenediamine-N,N'-bis[(o-hydroxyphenyl)acetic acid], ethylenediamine-N-[(o-hydroxyphenyl)acetic acid]-N'-[(p-hydroxyphenyl)acetic acid], ethylenediamine-N,N'-bis[o-hydroxyphenyl-methylphenyl]acetic acid], ethylenediamine-N-[o-hydroxy-methylphenyl]acetic acid]-N'-[(p-hydroxy-methylphenyl)acetic acid], or N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, and mixtures thereof.

[0053] In one embodiment, the conditioner used in the above method comprises urea. Surprisingly, it has also been found that adding a small amount of urea to the conditioner reduces the viscosity of such conditioners.

[0054] In one embodiment, the conditioner includes an antifoaming agent. One possible method of applying the conditioner to the solid particles is to spray the conditioner onto the particles. The particles may be in a rotating drum or on a bed. When spraying a composition containing an organic compound, there is always a risk of the composition foaming. Foam appears when air bubbles are trapped in a layer of the organic compound. To prevent this, an antifoaming agent can be added to the composition prior to the spraying operation. A variety of antifoaming agents are commercially available from suppliers, such as Synthron. The antifoaming agent is usually added in very small amounts, typically less than 1.0% by weight compared to the total composition, and does not affect the properties of the composition other than the foaming tendency.

[0055] In one embodiment, the conditioner contains an acid. In particular, the acid can be organic, i.e., a small molecule. More particularly, the acid can be a polycarboxylic acid, and even more particularly it can be selected from citric acid, malic acid, and mixtures thereof.

[0056] In one embodiment, the conditioner accounts for 0.1 to 2% by weight of the fertilizer particles, particularly 0.1 to 1.0% by weight.

[0057] On the other hand, there is provided a liquid composition comprising an iron chelate component and urea dissolved in a solvent selected from the group consisting of glycols, glycol ethers, and mixtures thereof, wherein the liquid composition contains at least 30 g / L of iron. On the other hand, a liquid composition comprising an iron chelate component and urea dissolved in a solvent selected from the group consisting of glycols, glycol ethers, and mixtures thereof, wherein the solvent accounts for about 30 to about 90% by weight of the conditioner. This aspect may exhibit the same or similar characteristics and technical effects as the first aspect, and vice versa.

[0058] The composition can be used to coat fertilizer particles to provide an iron source for the particles. Liquid compositions comprising a solvent selected from glycols and glycol ethers and an iron chelate component have been previously described in EP0334630. It has surprisingly been found that adding a small amount of urea to the previously described compositions reduces the viscosity of such compositions. When these compositions are applied to solid particles, such as fertilizer particles, the liquid composition has a suitable viscosity to enable the formation of a good and uniform coating.

[0059] In one embodiment, the solvent in the liquid composition is selected from the group consisting of monoethylene glycol, monopropylene glycol, diethylene glycol, 2-(2-ethoxyethoxy)ethanol, also known as diethylene glycol monoethyl ether, and mixtures thereof. Several examples of glycols and glycol ethers have been found to be particularly suitable for preparing compositions having an iron chelate and urea. Diethylene glycol monoethyl ether is classified as a non-hazardous substance and is therefore particularly suitable as a solvent.

[0060] In one embodiment, the liquid composition contains 30 to 90% by weight of the solvent, particularly 40 to 90% by weight of the solvent.

[0061] In one embodiment, the iron chelate component is an iron complex of a chelating agent selected from the group consisting of ethylenediamine-N,N'-bis[(o-hydroxyphenyl)acetic acid], ethylenediamine-N-[(o-hydroxyphenyl)acetic acid]-N'-[(p-hydroxyphenyl)acetic acid], ethylenediamine-N,N'-bis[o-hydroxy-methylphenyl]acetic acid], ethylenediamine-N-[o-hydroxy-methylphenyl]acetic acid]-N'-[(p-hydroxy-methylphenyl)acetic acid], N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, and mixtures thereof. Iron chelates are commercially available in a variety of different forms and contain different chelating ligands. The iron chelate is an iron chelate in which the oxidation value of iron is +3, so that iron is in the form of Fe(III) or Fe 3+ exists in the form of. Fe(III) can bind to polydentate ligands containing multiple electron donor atoms such as nitrogen and oxygen. Ligands containing a mixture of carboxylic acids, phenolic alcohols, and amines are well-known Fe(III) ligands.

[0062] In one embodiment, the liquid composition contains from about 0.1 to about 10% by weight of urea, based on the weight of the composition. The content of urea is preferably from about 1.0 to 10% by weight of the total liquid composition. If too much urea is used, the iron content will decrease and become too low for agricultural use. In particular, the liquid composition may contain from about 0.1 to about 5.0% by weight of urea, more particularly from about 0.1 to about 2.0% by weight of urea.

[0063] In one embodiment, the mass ratio of the iron chelate component to the solvent ranges from 1:9 to 3:1, particularly from 1:3 to 3:1, more particularly from 1:2 to 2:1. The ratio of the iron chelate to the solvent must be optimized to obtain a composition with the desired properties. The composition must have a suitable viscosity so that it can be applied to solid particles, and the iron content must be high enough to provide sufficient iron to plants in a minimum number of applications.

[0064] In one embodiment, the liquid composition contains an antifoaming agent.

[0065] In one embodiment, the liquid composition contains an acid. In particular, the acid can be organic, i.e., a small molecule. More particularly, the acid can be a polycarboxylic acid, and even more particularly it can be selected from citric acid, malic acid, and mixtures thereof.

[0066] In one embodiment, the pH value of the liquid composition is between 5.0 and 7.0.

[0067] On the other hand, there is provided the use of a composition comprising an iron chelate component dissolved in a solvent and optionally urea, said solvent being selected from the group consisting of glycols, glycol ethers, and mixtures thereof, as a coating agent for fertilizer granules.

[0068] In one embodiment, the composition used as a coating agent for fertilizer granules comprises about 30 to about 90% by weight of a solvent, particularly about 40 to about 90% by weight.

[0069] In another aspect, there is also provided the use of the liquid composition as described above as a coating agent for fertilizer granules.

[0070] This aspect may exhibit the same or similar characteristics and technical effects as the first aspect, and vice versa.

[0071] In one embodiment, the composition comprises an antifoaming agent.

[0072] In one embodiment, the composition comprises an acid. In particular, the acid can be organic, i.e., a small molecule. More particularly, the acid can be a polycarboxylic acid, and even more particularly it can be selected from citric acid, malic acid, and mixtures thereof. In one embodiment, the composition has a pH value between 5.0 and 7.0.

[0073] The present invention will now be further described with reference to the following examples.

[0074] Example 1

[0075] The following example shows the formulation required to prepare 1 kg of a liquid iron chelate composition based on high ortho-ortho FeEDDHA:

[0076] FeEDDHA (6% w / w Fe; 4.8% o-o) 475.7 g

[0077] Monoethylene glycol 524.3 g

[0078] Total 1000.0 g

[0079] Place the solvent in a glass container equipped with an impeller stirrer. Slowly add the iron chelate powder to the stirred solvent, controlling the addition rate in such a way as to avoid caking. After the addition is complete, continue stirring for 120 minutes to ensure complete dissolution. This process can be carried out at room temperature, or the solvent / mixture can be heated to 30 - 40 °C to accelerate dissolution.

[0080] The resulting product is a dark red-brown, slightly viscous solution with the following physicochemical properties:

[0081] Density: 1.226 kg / l at 20 °C

[0082] Viscosity (Brookfield, Spindle 3, 12 rpm) 1390 cP at 20 °C

[0083] Iron content: 2.85% w / w (= 35 g / l)

[0084] The product remains stable when stored at room temperature, 0 °C, and 45 °C for at least 8 weeks.

[0085] Example 2

[0086] The following example shows the formulation required to prepare 1 kg of a liquid iron chelate composition based on medium o,o content of FeEDDHA:

[0087]

[0088] The product was prepared in a similar manner to Example 1.

[0089] The resulting product is a dark red-brown, slightly viscous solution with the following physicochemical properties:

[0090] Density: 1.226 kg / l at 20 °C

[0091] Viscosity (Brookfield, Spindle 3, 12 rpm) 740 cP at 20 °C

[0092] Iron content: 2.85 % w / w (= 35 g / l)

[0093] The product can remain stable for 8 weeks at room temperature, 0 °C, and 45 °C.

[0094] Example 3

[0095] The following example shows the formulation required to prepare 1 kg of a liquid iron chelate composition based on FeHBED:

[0096]

[0097] The product was prepared in a similar manner to Example 1.

[0098] The resulting product is a dark red-brown, slightly viscous solution with the following physicochemical properties:

[0099] Density: 1.116 kg / l at 20 °C

[0100] Viscosity (Brookfield, Spindle 3, 12 rpm) 4600 cP at 20 °C

[0101] Iron content: 0.95 % w / w (= 11 g / l)

[0102] The product can remain stable for 8 weeks at room temperature, 0 °C, and 45 °C.

[0103] Example 4

[0104] The following examples show the formulation required to prepare 1 kg of a liquid iron chelate composition based on high ortho - ortho FeEDDHA:

[0105] FeEDDHA (6% w / w Fe; 4.8% o - o) 548.8 g

[0106] Diethylene glycol monoethyl ether 451.2 g

[0107] Total 1000.0 g

[0108] The product was prepared in a manner similar to Example 1.

[0109] The resulting product was a dark red - brown, slightly viscous solution with the following physicochemical properties:

[0110] Density: 1.320 kg / l at 20 °C

[0111] Viscosity (Brookfield, Spindle 3, 12 rpm) 1730 cP at 20 °C

[0112] Iron content: 3.29% w / w (= 43 g / l)

[0113] The product remained stable for 8 weeks at room temperature, 0 °C and 45 °C.

[0114] Example 5

[0115] The following examples show the formulation required to prepare 1 kg of a liquid iron chelate composition:

[0116] FeEDDHA (6% w / w Fe; 4.8% o - o) 452.6 g

[0117] Diethylene glycol 547.4 g

[0118] Total 1000.0 g

[0119] The product was prepared in a manner similar to Example 1.

[0120] The resulting product was a dark red - brown, slightly viscous solution with the following physicochemical properties:

[0121] Density: 1.292 kg / l at 20 °C

[0122] Viscosity (Brookfield, Spindle 3, 12 rpm) 2450 cP at 20 °C

[0123] Iron content: 2.72% w / w (= 35 g / l)

[0124] The product remained stable for 8 weeks at room temperature, 0 °C and 45 °C.

[0125] Example 6

[0126] The following example shows the formulation required to prepare 1 kg of a liquid iron chelate composition based on high ortho - ortho FeEDDHA using monoethylene glycol as the solvent:

[0127] FeEDDHA (6% w / w Fe; 4.8% o - o) 542.0 g

[0128] Monoethylene glycol 458.0 g

[0129] Total 1000.0 g

[0130] Place the solvent in a glass container under a Silverson high - shear rotor / stator mixer. Start the mixer and slowly add the iron chelate powder to the mixed solvent, controlling the addition rate to avoid caking. After addition is complete, continue mixing for 9 minutes to ensure complete dissolution.

[0131] The resulting product is a dark red - brown, slightly viscous solution with the following physical and chemical properties:

[0132] Density: 1.342 kg / l at 20 °C

[0133] Viscosity (Brookfield, Spindle 3, 12 rpm) 5650 cP at 20 °C

[0134] Iron content: 3.25% w / w (= 44 g / l)

[0135] Example 7

[0136] The following example shows the formulation required to prepare 1 kg of a liquid iron chelate composition based on high ortho - ortho FeEDDHA using monoethylene glycol as the solvent and incorporating urea:

[0137]

[0138] Prepare the product in a manner similar to Example 6, but dissolve the urea in the solvent before adding the iron chelate.

[0139] The resulting product is a dark red - brown, slightly viscous solution with the following physical and chemical properties:

[0140] Density: 1.344 kg / l at 20 °C

[0141] Viscosity (Brookfield, Spindle 3, 12 rpm) 3020 cP at 20 °C

[0142] Iron content: 3.25% w / w (= 44 g / l)

[0143] The comparison between Examples 6 and 7 demonstrated the effect of adding a small amount of urea in reducing the viscosity of the composition in a formulation using a high concentration of FeEDDHA with a high ortho - ortho content.

[0144] Example 8

[0145] The agronomic efficacy of the composition according to Example 2 was tested in replicated field trials on Bermuda grass. The study used a randomized complete block design with four replications. The iron chelate composition was coated onto granular compound NPK Fertilizer 21 - 7 - 14 at a rate of 3.8 kg / MT (equivalent to an iron concentration of 0.011% w / w on the carrier fertilizer). The following treatments were used to compare the coated fertilizer with an untreated control (no Fe input) and a conventional treatment using ferrous sulfate:

[0146] Treatment Serial Number Fertilizer Input Usage Rate 1 Untreated - 2 NPK 21-7-14 232 kg / ha 3 NPK 21-7-14 plus Ferrous Sulfate 232 kg / ha + 2 units of Fe 4 NPK 21-7-14 Coated with the Fe Composition of Example 2 232 kg / ha

[0147] The solid fertilizers were spread onto individual plots of Bermuda grass using conventional fertilizer spreading equipment. Various quality parameters of these plots, including leaf color, were evaluated regularly after treatment, and the results are shown in the following table:

[0148]

[0149] (Different letters indicate significant differences)

[0150] In terms of leaf color, Treatment 4 (involving NPK fertilizer coated with the iron chelate composition) performed better than other treatments, including the conventional treatment using ferrous sulfate. At 6 days and 34 days, the improvement in leaf color scores was statistically significant compared to the conventional ferrous sulfate treatment. Improvements in overall turf quality and biomass were also observed for Treatment 4 compared to other treatments.

[0151] This trial demonstrated that using the iron chelate composition as a coating on solid fertilizers is an effective and convenient method for delivering iron to treat iron deficiency, even though the iron level applied is relatively low compared to conventional practices.

[0152] Example 9

[0153] Tests were conducted to evaluate the effect of the above - mentioned iron chelate composition on the quality parameters of fertilizers when coated onto solid granular fertilizers. Aqueous iron chelate compositions prepared according to WO0304128 and EP0334630 were also tested for comparison. The strength of fertilizer granules / pellets ( = crush resistance, hardness) is an important property for quality control in fertilizer production. Crush resistance is one of the main parameters for evaluating the physical properties of fertilizers and is greatly affected by the free water content in the fertilizer.

[0154] Using a laboratory-scale conical mixer, each iron chelate composition was applied to granular urea (particle size approximately 3 mm) at a rate equivalent to 5 liters per metric ton (equivalent to approximately 0.65 wt% of the final product). 1 kg of urea was added to the blender, and an appropriate amount of the iron chelate composition was added to the fertilizer being mixed in the rotating blender. Mixing was continued for 20 seconds after addition to ensure that the iron chelate composition was fully distributed and coated on the urea. The treatments used were as follows:

[0155] 1. Control - untreated

[0156] 2. 5 L / mt anhydrous iron chelate composition according to Example 4 above

[0157] 3. 5 L / mt water-based iron chelate composition according to Example 1 in WO03042128

[0158] 4. 5 L / mt water / solvent-based iron chelate composition according to Example 1 in EP0334630

[0159] Note: "mt" is metric ton = 1000 kg.

[0160] Before testing the crushing strength of the granules according to the following method using a Hi-way New Leader hardness tester, the coated urea was bagged and stored for one week.

[0161] A single granule was placed on a smooth, solid surface (laboratory bench), and the plunger of the tester was placed above the granule. The tester was depressed until the granule broke, and the scale reading was recorded.

[0162] The tests were conducted at room temperature (approximately 20 °C), and 20 repetitions were performed for each treatment. The results are shown below.

[0163] Serial Number Treatment Crushing Strength 1 Untreated Control 3.7 2 5 L / mt Anhydrous Composition According to Example 4 3.4 3 5 L / mt Aqueous Composition According to Example 1 in WO03042128 2.3 4 5 L / mt Water / Solvent-Based Composition According to Example 1 in EP0334630 2.4

[0164] Fertilization guidelines recommend that any granule with a crushing strength less than 3 should not be spread at a rotational speed exceeding 700 revolutions per minute.

[0165] The results clearly show that, compared to the aqueous compositions disclosed in the prior art, the compositions according to the present invention have a lesser impact on the strength of fertilizer granules.

[0166] Example 10

[0167] Caking tendency is another very important fertilizer quality parameter. Tests were conducted to evaluate the effect of the above iron chelate compositions on the caking tendency when coated onto granular calcium ammonium nitrate (CAN). Again, aqueous iron chelate compositions prepared according to WO03042128 and EP0334630 were tested for comparison.

[0168] Using a laboratory-scale conical mixer, each iron chelate composition was applied to granular CAN at a rate required to add 0.02% w / w Fe to the fertilizer. 1 kg of CAN was added to the mixer, and an appropriate amount of the iron chelate composition was added to the fertilizer while the fertilizer was being mixed in the rotating mixer. Mixing was continued for 20 seconds after addition to allow thorough distribution and coating of the iron chelate composition on the CAN. The treatments used were as follows:

[0169] 1. 5 L / mt anhydrous iron chelate composition according to Example 6 above

[0170] 2. 5 L / mt anhydrous iron chelate composition according to Example 7 above

[0171] 3. 6.7 L / mt water-based iron chelate composition according to Example 1 in WO03042128

[0172] 4. 3.7 L / mt water / solvent-based iron chelate composition according to Example 1 in EP0334630

[0173] 500 g samples of the coated CAN were placed in plastic bags, sealed and stored at 50 °C under a 1 kg weight for 10 days. The bags were then opened and the fertilizer was evaluated for signs of caking. The results were as follows:

[0174] Serial Number Treatment Evaluation 1 5 L / mt Anhydrous Composition According to Example 6 Granular; No Caking 2 5 L / mt Anhydrous Composition According to Example 7 Granular; No Caking 3 5 L / mt Aqueous Composition According to Example 1 in WO03042128 Caking 4 5 L / mt Water / Solvent Composition According to Example 1 in EP0334630 Caking

[0175] The results clearly show that, compared to the aqueous compositions disclosed in the prior art, the anhydrous compositions according to the present invention have a lesser effect on the tendency of fertilizer particles to cake.

[0176] Example 11

[0177] A conditioner containing the following components was prepared:

[0178]

[0179] The pH value of the conditioner was 7.0.

[0180] The product was prepared in a manner similar to Example 6, except that the urea was dissolved in monoethylene glycol before adding the iron chelate component.

[0181] The conditioner was coated onto fertilizer granules containing calcium ammonium nitrate (CAN) at a rate of 3 L / mt. The same conditioner was prepared without citric acid, with the amounts of the other components remaining unchanged, and the conditioner was coated onto the granules containing CAN. Uncoated CAN granules were used as a control. 100 g samples of the three batches of granules were weighed into 2-liter plastic bottles, sealed with stoppers and a Drager tube was inserted to measure the ammonia concentration over 8 hours and 24 hours. The results were as follows:

[0182]

Claims

1. An anhydrous liquid composition comprising an iron chelate component and urea dissolved in a solvent, said solvent being selected from the group consisting of glycols, glycol ethers and mixtures thereof, wherein said liquid composition contains at least 30 g / L of iron and said composition contains from 0.1 to 5.0% by weight of urea relative to the weight of said composition.

2. The anhydrous liquid composition according to claim 1, wherein, Said composition contains from 0.1 to 2.0% by weight of urea relative to the weight of said composition.

3. The anhydrous liquid composition according to claim 1, characterized in that, Said composition contains from 30 to 90% by weight of solvent.

4. The anhydrous liquid composition according to claim 1, characterized in that, Said solvent is selected from the group consisting of monoethylene glycol, monopropylene glycol, diethylene glycol, 2-(2-ethoxyethoxy)ethanol and mixtures thereof.

5. The anhydrous liquid composition according to claim 1, characterized in that, The mass ratio of said iron chelate component to the solvent is in the range of 1:9 to 3:

1.

6. The anhydrous liquid composition according to claim 1, characterized in that, The pH of said anhydrous liquid composition is between 5.0 and 9.

0.

7. The anhydrous liquid composition according to claim 1, characterized in that, The pH of said anhydrous liquid composition is between 5.0 and 7.

0.

8. The anhydrous liquid composition according to claim 1, characterized in that, Said anhydrous liquid composition comprises an acid selected from the group consisting of citric acid, malic acid and mixtures thereof.

9. The anhydrous liquid composition according to claim 1, characterized in that, Said iron chelate component is an iron chelate of a chelating agent, wherein said chelating agent is an amino alcohol or an aminopolycarboxylic acid.

10. The anhydrous liquid composition according to claim 9, characterized in that, Said chelating agent is selected from the group consisting of ethylenediamine-N,N'-bis[(o-hydroxyphenyl)acetic acid], ethylenediamine-N-[(o-hydroxyphenyl)acetic acid]-N'-[(p-hydroxyphenyl)acetic acid], ethylenediamine-N,N'-bis[o-hydroxy-methylphenyl]acetic acid], ethylenediamine-N-[o-hydroxy-methylphenyl]acetic acid]-N'-[(p-hydroxy-methylphenyl)acetic acid] or N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid and mixtures thereof.

11. The anhydrous liquid composition according to claim 1, characterized in that, Said anhydrous liquid composition contains at least 35 g / L of iron.

12. The anhydrous liquid composition according to claim 1, characterized in that, Said anhydrous liquid composition contains at least 40 g / L of iron.

13. The anhydrous liquid composition according to claim 1, characterized in that, Said anhydrous liquid composition contains at least 44 g / L of iron.

14. The anhydrous liquid composition according to claim 1, wherein, The mass ratio of said iron chelate component to the solvent is in the range of 1:2 to 2:

1.

15. The anhydrous liquid composition according to claim 1, wherein, Said anhydrous liquid composition comprises an antifoaming agent.

Images