Manufacture of composite fertilizer granules Manufacture of composite fertilizer granules

Abstract

A method of forming a granular fertilizer product, the method comprising: forming a first mixture of phosphoric acid and ammonia; adding the first mixture and a halite powder to a granulator to form a second mixture; and providing ammonia to the second mixture to complete the formation of ammonium phosphate within the second mixture while the granulator processes the second mixture to form granules.

Description

Technical Field

[0001] This invention relates to a method for forming fertilizer granules and a fertilizer granule. Background Technology

[0002] A common way to supplement plants with available nutrients is to treat seedbeds, fields, or other growing media with fertilizer products in the form of aggregated granules. Granular products have the advantages of being stable, easy to spread using conventional horticultural or agricultural machinery, and easy to distribute at the desired application rate.

[0003] A wide variety of fertilizer ingredients are available. The effectiveness of a particular fertilizer ingredient depends on a number of factors, including the type of plant to which it will be applied, the maturity of the plant, the current condition of the growing medium, and environmental conditions.

[0004] The main plant nutrients include nitrogen, phosphorus, potassium, magnesium, calcium, and sulfur. In fertilizer formulations, these individual nutrients can be combined through any of the many compounds contained within them. Although different compounds may contain the same basic nutrients, the bioavailability of these nutrients can vary depending on the mechanisms by which the compounds are broken down. Nutrient bioavailability can also vary due to other aspects of the fertilizer's chemical or mechanical formulation. For example, some fertilizer granules may contain a slowly decomposing coating or binder to delay nutrient release; some compounds may rely on the microbial community in the growth medium to release their nutrients; and some components may provide nutrients in a chelated form to enhance their absorption.

[0005] To provide a variety of nutrients, growers can apply multiple different fertilizer components or a single multinutrient fertilizer component. For a multinutrient to be effective, its constituent compounds must be in an appropriate balanced ratio and must be able to function effectively even in the presence of other components. This effectiveness may depend on factors other than fertilizer content: such as ambient water, heat, or the presence of certain microbial communities. The effectiveness of multinutrient fertilizers on plants (especially in cases dependent on environmental factors) is difficult to predict. However, if a multinutrient fertilizer component is effective, its advantage is that it can be applied to the crop with only a single dispersing operation.

[0006] Certain minerals, particularly evaporite minerals, can be used as sources of nutrients such as potassium, calcium, magnesium, and sulfur. For example, gypsum can be granulated and used as a source of calcium and sulfur.

[0007] Carnallite is an evaporite mineral. It is a hydrated sulfate complex of potassium, calcium, and magnesium, with the general formula K₂Ca₂Mg(SO₄)₄·2H₂O. Carnallite deposits are distributed in Austria, China, Germany, India, Iran, Turkey, Ukraine, the United Kingdom, and the United States.

[0008] Carnallite can serve as a valuable source of agricultural fertilizer. In some existing technological processes, the decomposition of natural carnallite has been proposed to extract specific nutrients. See, for example, WO 2013 / 074328, US 1946068, and US4246019. However, intact carnallite can also be used as fertilizer, providing sulfur, potassium, calcium, and magnesium to the soil.

[0009] Carnallite can be dispersed in raw, crushed form. This minimizes processing costs but also has several drawbacks. Once applied to the soil, the raw mineral requires time to decompose, thus delaying the bioavailability of its components. When applied in crushed form, carnallite tends to have irregular shapes and sizes, meaning it is difficult to apply evenly and may be challenging to use certain types of agricultural dispersing machinery. Powdered carnallite is difficult to disperse evenly in agricultural applications, and because carnallite powder can be hygroscopic, its mechanical properties change rapidly and drastically over time once exposed to air.

[0010] There is a desire for a fertilizer product that is easy to distribute and provides a large amount of nutrients in a way that is particularly beneficial to plants. Summary of the Invention

[0011] According to a first aspect of the present invention, a method for forming a granular fertilizer product is provided, the method comprising: forming phosphoric acid and a first mixture with ammonia; adding the first mixture and carnallite powder into a granulator to form a second mixture; and providing ammonia to the second mixture to complete the formation of ammonium phosphate within the second mixture while the second mixture is being processed in the granulator to form granules.

[0012] A granulator can process a second mixture to form granules by mixing a second mixture while supplying ammonia. Forming a first mixture of phosphoric acid and ammonia may include mixing phosphoric acid while introducing ammonia into the phosphoric acid. Ammonia present in the first mixture can react with phosphoric acid to form ammonium phosphate, and ammonia may be introduced in an amount insufficient to completely form ammonium phosphate in the first mixture. Supplying ammonia to the second mixture may include introducing ammonia gas into the second mixture. Supplying ammonia to the second mixture may include introducing liquid ammonia into the second mixture. Ammonia present in the second mixture can react with phosphoric acid to form ammonium phosphate, and ammonia may be introduced in an amount sufficient to completely form ammonium phosphate in the second mixture. A predetermined ratio of ammonia to phosphoric acid can complete the formation of ammonium phosphate from phosphoric acid, and ammonia may be introduced into the first mixture in an amount less than the predetermined ratio. A predetermined ratio of ammonia to phosphoric acid can complete the formation of ammonium phosphate from phosphoric acid, and ammonia may be introduced into the second mixture to substantially satisfy the predetermined ratio.

[0013] Forming a first mixture of phosphoric acid and ammonia may include adding a liquid to the first mixture. The liquid may be water. The liquid may be ammonia.

[0014] The powder's average particle size can range from 50 to 500 μm. The particles may comprise a mixture of over 80% by weight of carnallite powder and ammonium phosphate. A certain amount of the first mixture may be added to the carnallite powder such that the particles comprise 20%-80% by weight of ammonium phosphate.

[0015] According to a second aspect of the invention, fertilizer granules are provided that are mainly composed of a mixture of carnallite powder and ammonium phosphate.

[0016] The granules may include 60%-80% ammonium phosphate by weight. The granules may include 20%-40% carnallite powder by weight. The granules may include a mixture of carnallite powder and ammonium phosphate by weight of more than 80%.

[0017] According to a third aspect of the invention, a fertilizer product is provided comprising a plurality of granules as described herein. According to a fourth aspect of the invention, a granular fertilizer product is provided, wherein at least 50% of the granules are the granules described herein. Attached Figure Description

[0018] The invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

[0019] Figure 1 It shows an overall overview of the fertilizer production process. Detailed Implementation

[0020] The following description is provided to enable any person skilled in the art to make and use the invention, and is given in the context of a particular application. Various modifications to the disclosed embodiments will be apparent to those skilled in the art.

[0021] The general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the invention. Therefore, the invention is not intended to be limited to the embodiments shown, but should be accorded the widest scope of the principles and features disclosed herein.

[0022] This invention relates to a method for forming granular fertilizer products. The method includes forming a first mixture of phosphoric acid and ammonia, and adding the first mixture and carnallite powder into a granulator to form a second mixture. The method further includes providing ammonia to the second mixture to simultaneously complete the formation of ammonium phosphate within the second mixture while the granulator processes the second mixture to form granules. The invention also relates to fertilizer granules consisting primarily of a mixture of carnallite powder and ammonium phosphate.

[0023] Figure 1 This displays an overall overview of the fertilizer production process. The production process will refer to... Figure 1 Describe it.

[0024] As described above, carnallite is a hydrated sulfate complex of potassium, calcium, and magnesium, with the general formula K₂Ca₂Mg(SO₄)₄·2H₂O. Carnallite has a Mohs hardness of approximately 2.5-3.5. Carnallite can be extracted from nature reserves through mining. As-mined carnallite may be tightly bound to other minerals, which form impurities within the carnallite. These other minerals are preferably present in low proportions (e.g., less than 10% or less than 5% in high-quality ore). Once mined, carnallite can be crushed into blocks or chips of suitable size for easy transport and processing. For example, mined ore can be fed to crushers such as jaw crushers and / or cone crushers to produce fragments of generally uniform size. It has been found that chips with a maximum size of no more than about 20 mm and / or an average size of 5-10 mm are easy to transport from the mine. The chips can be transported by conveyors, trucks, or any other convenient mechanical means.

[0025] As indicated by arrow 2, carnallite fragments are loaded into the first hopper 1. The carnallite fragments are then discharged from the first hopper to be processed into powder form.

[0026] Raw polyhalite or polyhalite fragments are processed into a powder composed primarily of polyhalite. This can be appropriately carried out using a high-pressure grinding roller (HPGR) device or in a ball mill (e.g., a continuous Hardinge ball mill) or grinder. The average particle size of the powder depends on various process parameters, including the residence time of the raw material in the pulverizing equipment and the configuration of the pulverizing equipment. Oversized particles leaving the pulverizing equipment can be returned to the equipment for further processing. The desired powder size will depend on the nature of subsequent processing steps, but it has been found that screening the output of the pulverizing process with a 500 μm sieve and accepting the material that passes through the sieve for further processing yields good results. Oversized particles leaving the pulverizing equipment that do not pass through the sieve can be returned to the pulverizing equipment for further processing. The preferred profile of the powder entering the next step of the process is: 100% passing through a 500 μm sieve and 80% (by mass) passing through a 200 μm sieve. Conveniently, at least 50% or more preferably at least 70% of the powder mass consists of particles with a particle size or maximum or average diameter in the range of 50-500 μm, more preferably in the range of 100-250 μm. The particle size can be measured by a Malvern Mastersizer 3000 particle size analyzer or by a shaking sieve.

[0027] Impurities in mined ore can be separated before the ore is pulverized. Alternatively, if the proportion of impurities relative to the desired mineral is relatively low, the impurities can be retained and the ore pulverized. Therefore, powdered carnallite can also include other minerals.

[0028] Powdered carnallite passes through air cyclone 4. Air cyclone 4 separates the powdered carnallite into particles of the desired size, while excessively large particles fall back into air cyclone 4 for recycling. The output from air cyclone 4 is loaded into a second hopper 5. The output from the second hopper 5 is directed to a device that can both mix and granulate. Therefore, the second hopper 5 can output to... Figure 1 In the pellet mill 6 shown.

[0029] The granulator 6 is also supplied with liquid from the pre-neutralizer 7 and from the first storage tank 8. The first storage tank 8 contains liquid ammonia or ammonia gas. In this process, it is possible to use both liquid ammonia and ammonia gas. In this case, separate storage tanks may be used for liquid ammonia and ammonia gas. It should be understood that reference to either liquid ammonia or ammonia gas can refer to the use of a portion of each or the use of one followed by the use of the other. Alternatively, in this process, only liquid ammonia or ammonia gas may be used.

[0030] The second storage tank 9 contains phosphoric acid. The first storage tank 8 and the second storage tank 9 are connected to a pre-neutralizer 7. The pre-neutralizer 7 is supplied with phosphoric acid from the second storage tank 9 and liquid ammonia / ammonia gas from the first storage tank 8. A certain amount of phosphoric acid can be introduced into the pre-neutralizer 7, and then liquid ammonia / ammonia gas is supplied to the phosphoric acid through a pipe, causing the liquid ammonia / ammonia gas to be bubbled through the phosphoric acid and react with the acid. The pre-neutralizer 7 may include a mixing paddle 10 to mix the liquids present in the pre-neutralizer. The combination of phosphoric acid and liquid ammonia / ammonia gas in the pre-neutralizer 7 forms a first mixture of phosphoric acid and ammonia. The first mixture may be in the form of a slurry.

[0031] When liquid ammonia / ammonia gas is introduced into phosphoric acid, the liquid ammonia / ammonia gas reacts with the phosphoric acid. This reaction produces ammonium phosphate. The introduction of liquid ammonia / ammonia gas lowers the pH of the first mixture. The amount of liquid ammonia / ammonia gas introduced can be chosen to lower the pH of the first mixture to approximately 5-6. Monoammonium phosphate (MAP), diammonium phosphate (DAP), or a combination of both can be produced in the first mixture in the pre-neutralizer, depending on the amount of liquid ammonia / ammonia gas introduced into the phosphoric acid. The amount of liquid ammonia / ammonia gas introduced into the first mixture is less than the amount required to complete the formation of ammonium phosphate (whether in MAP or DAP form as needed). This means that when the formation of ammonium phosphate is complete, there is essentially no residual phosphoric acid in the mixture.

[0032] A predetermined ratio of ammonia to phosphoric acid is present, which completes the formation of ammonium phosphate from phosphoric acid. This predetermined ratio can be a target ratio. This predetermined ratio depends on whether MAP or DAP is being produced. The predetermined ratio for MAP is 1:1. The predetermined ratio for DAP is 2:1.

[0033] Water can also be introduced into the pre-neutralizer to assist in the mixing of phosphoric acid and ammonia.

[0034] The pre-neutralizer 7 is connected to the granulator 6, allowing the pre-neutralizer 7 to supply the granulator 6 with a first mixture of phosphoric acid and ammonia. A first storage tank is also connected to the granulator 6, allowing the direct supply of liquid ammonia / ammonia gas to the granulator 6.

[0035] An example of such pelletizing equipment is a high-intensity mixer / granulator, available for example from Maschinenfabrik Gustav Eirich GmbH & Co KG (Gustav Eirich GmbH & Co KG, Germany). The pelletizer can be configured to discharge processed material during operation, allowing for continuous operation. Alternatively, the pelletizer can operate in batches, processing material according to a prescribed procedure and then discharging it in large quantities.

[0036] The carnallite powder enters the granulator 6 from the second hopper 5. The first mixture also enters the granulator 6 from the pre-neutralizer 7. The amount of carnallite powder and the first mixture entering the granulator 6 is selected according to the desired ratio of carnallite to ammonium phosphate in the final granules. The addition of the carnallite powder and the first mixture forms a second mixture through mixing by the granulator 6.

[0037] Liquid ammonia / gas is injected from the first storage tank 8 into the granulator. Liquid ammonia / gas is thus injected into the second mixture. The amount of liquid ammonia / gas injected is selected to complete the formation of ammonium phosphate in the second mixture. The second mixture can be tested to determine when its pH reaches approximately 7, indicating that the formation of ammonium phosphate within the second mixture is complete. The ammonium phosphate in the second mixture can be in the form of DAP or MAP, depending on the amount of ammonia introduced into the pre-neutralizer 7 and the granulator 6.

[0038] The introduction of liquid from the pre-neutralizer 7 also has the effect of causing the heterohalite powder to agglomerate, and thus causing the second mixture to agglomerate and granulate in the granulator 6.

[0039] The amount of the first mixture and ammonia introduced into the granulator can be selected according to the required ratio of the carnallite powder to ammonium phosphate in the granules. The weight ratio of carnallite powder to ammonium phosphate in the granules can typically be 1:10, 1:5, 3:10, 2:5, 1:2, 3:5, 7:10, 4:5, 9:10, 1:1, 10:9, 5:4, 10:7, 5:3, 2:1, 5:2, 10:3, 5:1, or 10:1.

[0040] The particles may include more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, and more than 80% of carnallite by weight. Preferably, the fertilizer product may include less than 80% of carnallite by weight, more preferably less than 60%, more preferably 20%-40%, and more preferably 20%-35%.

[0041] The granules may comprise more than 20%, more than 30%, more than 40%, more than 50%, more than 60%, more than 70%, or more than 80% of ammonium phosphate by weight. Preferably, the fertilizer product may comprise more than 20% of ammonium phosphate by weight, more preferably more than 40%, more preferably 60%-80%, and even more preferably 65%-80%.

[0042] The granules may consist primarily of a mixture (by weight) of carnallite powder and ammonium phosphate. The granules may comprise, by weight, more than 80% of a mixture of carnallite powder and ammonium phosphate, more than 85% of a mixture of carnallite powder and ammonium phosphate, 90% of a mixture of carnallite powder and ammonium phosphate, 95% of a mixture of carnallite powder and ammonium phosphate, 96% of a mixture of carnallite powder and ammonium phosphate, 97% of a mixture of carnallite powder and ammonium phosphate, 98% of a mixture of carnallite powder and ammonium phosphate, 99% of a mixture of carnallite powder and ammonium phosphate, or 99.5% of a mixture of carnallite powder and ammonium phosphate.

[0043] Upon completion of the granulation process, the granules are discharged from granulator 6 and enter dryer 14, which may be a conveyor for drying. The granules contain ammonium phosphate and carnallite. It has been found that a residence time of approximately 3 minutes in dryer 14, which is capable of heating the granules to approximately 150°C, is sufficient to adequately dry the granules. This hardens the granules. The crush strength of granules made using carnallite powder, phosphoric acid, and ammonia can be in the range of 2.2 kgf. This is good compared to the generally accepted lower limit of 2.2 kgf for agricultural granules. Moisture can be removed from the dryer using a reversejet air filter. The operating temperature and residence time of the dryer can be selected to provide granules of the desired strength for subsequent processing. A rotary dryer can be used to dry the granules.

[0044] The dried material discharged from dryer 14 can be screened to separate particles that are too small and / or too large from those within the desired size range. For example, the desired size range could be one that passes through a 4mm screen but not a 2mm screen. Alternatively, other sizes can be selected depending on the desired application.

[0045] The dried granules can be screened by a first-size screen 12 to separate oversized particles from those with the desired upper limit size. The oversized particles are retrinded. This can be done using a high-pressure grinding roller (HPGR) device 16 or in a ball mill (e.g., a continuous Hardinge ball mill) or atritor mill. The retrinded granules are fed to a second hopper 5 for recycling through the process again. The dried granules can be screened by a second-size screen 13 to separate undersized particles from those with the desired lower limit size. The undersized particles are fed back to the second hopper 5 to be reintroduced into the pellet mill 6 for recycling through the process again.

[0046] Finally, appropriately sized granules (as indicated by arrow 17) can be cooled and packaged, for example, in 600 kg bags or 25 kg sacks, or transported in bulk for use elsewhere or further processing. These granules are suitable for agricultural use. Ultimately, they can be used as fertilizer spread on fields or other agricultural or horticultural substrates. Compound granules can be used for purposes other than fertilization.

[0047] Other additives may be included in the granules. Such additives may be one or more of the following, in any combination:

[0048] - Ingredients that have chemical and / or mechanical stabilizing and / or preserving effects on particles: for example, increasing the shelf life of particles, reducing the susceptibility of particles to environmental pollutants, or reducing the likelihood of particles breaking during dispersal (e.g., pH buffers).

[0049] - Ingredients that enhance the effects of carnallite and / or ammonium phosphate fertilization: for example, by accelerating or delaying the decomposition of carnallite in the field;

[0050] - Ingredients that have the effect of protecting or promoting crop growth through means other than fertilization: such as herbicides, fungicides, insecticides, rodenticides, hormones, plant stimulants, or mycorrhizal fungi or spores;

[0051] - Seeds: These may be seeds of angiosperms, gymnosperms, and / or crops (such as grains like wheat, corn, rice, millet, barley, oats, or rye);

[0052] - Another fertilizer composition that provides macronutrients or micronutrients in addition to carnallite and ammonium phosphate;

[0053] -pigment;

[0054] - Components that can alter soil pH: such as lime or sulfur.

[0055] Such components can be added at any suitable stage of the process. For example, it can be combined with carnallite powder, or with a carnallite / phosphate / ammonia mixture, or with a phosphate / ammonia mixture, before or after drying, or it can be sprayed or coated onto the granules.

[0056] The composite particles are preferably substantially free of voids, for example, having no more than 1%, 2% or 5% air by volume.

[0057] Where the properties of a single particle are specified above, the standard may be applied to bulk granular fertilizers, such as (i) the average value of the bulk, (ii) the median value of the bulk, or (iii) more than 50% or 80% of the bulk fertilizer particles having the necessary properties.

[0058] In all three embodiments, a DAP pre-neutralizer slurry is produced by mixing phosphoric acid and ammonia to achieve a pH of 5-6. Carbohydrate powder is weighed and added to a granulation mixer. The carbohydrate powder is mixed in the granulation mixer, and the slurry is added to the carbohydrate powder by pouring. Ammonia is then injected into the mixture. Once the slurry-powder mixture reaches a pH of approximately 7, the mixture is heated to dry it and granulation begins. Granules are formed and sieved using a Tyler 5-9 sieve to obtain particles of the desired 2-4 mm size.

[0059] In the first embodiment, 3.36 kg of phosphoric acid was added to a pre-neutralizer and mixed while ammonia was bubbled in until the pH reached approximately 6. 1550 mL of water was added throughout the process to help the mixture pass through the insoluble stage as it traversed a pH range of 1.6–5. 1 kg of carnallite was added to a granulation mixer and introduced into a slurry. Ammonia was bubbled in until the pH reached approximately 7, and the mixture was then granulated to produce pellets. The resulting pellets were screened to obtain the desired pellet size of 2–4 mm. The resulting pellets had a hardness of 2.3 kgf. By weight, the resulting pellets contained 80% DAP and 20% carnallite powder.

[0060] In the second embodiment, 2.73 kg of phosphoric acid was added to a pre-neutralizer and mixed while ammonia was bubbled in until the pH reached approximately 6. 1250 mL of water was added throughout the process to help the mixture pass through the insoluble stage as it traversed a pH range of 1.6–5. 1.75 kg of carnallite was added to a granulation mixer and introduced as a slurry. Ammonia was bubbled in until the pH reached approximately 7, and the mixture was then granulated to produce pellets. The resulting pellets were screened to obtain the desired pellet size of 2–4 mm. The resulting pellets had a hardness of 2.1 kgf. By weight, the resulting pellets contained 65% DAP and 35% carnallite powder.

[0061] In the third embodiment, 1.68 kg of phosphoric acid was added to a pre-neutralizer and mixed while ammonia was bubbled in until the pH reached approximately 6. 1000 mL of water was added throughout the process to help the mixture pass through the insoluble stage as it traversed a pH range of 1.6–5. 3 kg of carnallite was added to a granulation mixer and introduced as a slurry. Ammonia was bubbled in until the pH reached approximately 7, and the mixture was then granulated to produce pellets. The resulting pellets were screened to obtain the desired pellet size of 2–4 mm. The resulting pellets had a hardness of 2.1 kgf. By weight, the resulting pellets contained 40% DAP and 60% carnallite powder.

[0062] The applicant hereby independently discloses each individual feature described herein, as well as any combination of two or more such features, provided that such features or combinations can be implemented based on the entire specification in accordance with common general knowledge of those skilled in the art, regardless of whether such features or combinations of features solve any problem disclosed herein, and without limiting the scope of the claims. The applicant notes that aspects of the invention can consist of any such individual features or combinations of features. In view of the foregoing description, it will be apparent to those skilled in the art that various modifications can be made within the scope of the invention.

Claims

1. A method for forming a granular fertilizer product, the method comprising: A first mixture of phosphoric acid and ammonia is formed; The first mixture and carnallite powder are added to a granulator to form a second mixture; and Ammonia is supplied to the second mixture to complete the formation of ammonium phosphate within the second mixture while the second mixture is being processed in the granulator to form granules.

2. The method of claim 1, wherein the granulator processes the second mixture to form granules by mixing the second mixture while providing ammonia.

3. The method according to claim 1 or 2, wherein forming the first mixture of phosphoric acid and ammonia comprises mixing the phosphoric acid while introducing ammonia into the phosphoric acid.

4. The method of claim 1, wherein the ammonia present in the first mixture reacts with the phosphoric acid to form ammonium phosphate, and the ammonia is introduced in an amount insufficient to completely form ammonium phosphate in the first mixture.

5. The method of claim 1, wherein providing ammonia to the second mixture comprises introducing ammonia gas into the second mixture.

6. The method of claim 1, wherein providing ammonia to the second mixture comprises introducing liquid ammonia into the second mixture.

7. The method of claim 1, wherein the ammonia present in the second mixture reacts with the phosphoric acid to form ammonium phosphate, and the ammonia is introduced in an amount sufficient to completely form ammonium phosphate in the second mixture.

8. The method of claim 1, wherein a predetermined ratio of ammonia to phosphoric acid completes the formation of ammonium phosphate from phosphoric acid, and a certain amount of ammonia is introduced into the first mixture in an amount less than the predetermined ratio.

9. The method of claim 1, wherein a predetermined ratio of ammonia to phosphoric acid completes the formation of ammonium phosphate from phosphoric acid, and the ammonia is introduced into the second mixture to satisfy the predetermined ratio.

10. The method of claim 1, wherein forming the first mixture of phosphoric acid and ammonia comprises adding a liquid to the first mixture.

11. The method of claim 10, wherein the liquid is water.

12. The method of claim 10, wherein the liquid is ammonia.

13. The method according to claim 1, wherein the mass-average particle size of the powder is in the range of 50-500 μm.

14. The method of claim 1, wherein the particles comprise a mixture of more than 80% by weight of carnallite powder and ammonium phosphate.

15. The method of claim 1, wherein a certain amount of the first mixture is added to the carnallite powder such that the particles comprise 20%-80% ammonium phosphate by weight.

16. The method of claim 1, wherein a certain amount of the first mixture is added to the carnallite powder such that the particles comprise 20%-80% carnallite powder by weight.

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