Acidified fertilizer granules

Abstract

Disclosed are methods for preparing solid acidic fertilizer granules, solid acidic fertilizer granules, and methods for using the same in fertigation. The methods may include providing plant nutrients containing nitrogen (N), phosphorus (P), and optionally potassium (K) in a container; feeding an acid solution containing a mineral acid at an average feed rate of 0.2 to 0.8 metric tons of mineral acid (MT acid) per metric ton of plant nutrients (MT nutrient) per hour (MT acid·h ‑1 MT nutrients ‑1 ) into a container at a feed rate of 1.5 wt % to 2.5 wt % to contact the inorganic acid and the plant nutrients to obtain acidified granules having an average moisture content of 0.5 wt % to 1.0 wt %; and drying the acidified granules to obtain dried acidic granules.

Description

[0001] Cross-references to Related Patent Applications

[0002] This application claims priority to and the benefit of priority from Indian Provisional Application No. 202011029906, filed on July 14, 2020, which is incorporated herein by reference in its entirety. Background Art

[0003] A. Field of the Invention

[0004] The present invention generally relates to a method for preparing acidified fertilizers. More particularly, the method comprises contacting a mineral acid with a plant nutrient comprising nitrogen, phosphorus, and optionally potassium at a controlled rate to produce solid acidified fertilizer granules.

[0005] B. Description of Related Prior Art

[0006] Soil nutrients such as nitrogen, phosphorus, potassium, and sulfur, as well as trace elements like iron, zinc, copper, and magnesium, are essential for agricultural prosperity and plant growth. After repeated cropping cycles, soil levels of these nutrients can become depleted, leading to stunted plant growth and reduced yields. To counteract this effect, fertilizers have been developed to help replace depleted vital nutrients and create the right nutrient balance.

[0007] Traditionally, fertilizers are distributed to the soil through drip irrigation, where fertilizer granules or powders are applied directly to the soil. In contrast, fertigation, a method widely used in commercial agriculture and horticulture, applies fertilizers through irrigation systems by dissolving them directly in the irrigation system. Advantages of fertigation include increased nutrient uptake by plants, precise nutrient delivery, reduced fertilizer consumption, reduced soil erosion, and reduced energy required to apply solid fertilizers. However, most conventional NP (nitrogen-phosphorus), PK (phosphorus-potassium), and NPK (nitrogen-phosphorus-potassium) fertilizers are incompletely soluble in irrigation water with high pH (pH > 7.5) and / or calcium levels exceeding 50 ppm. The phosphorus in the fertilizer can react with calcium in the water at high pH to form insoluble calcium phosphate complexes. This reduced solubility results in uneven distribution of the fertilizer in the water. Furthermore, the formation of insoluble calcium phosphate complexes can lead to particle accumulation in the irrigation system, resulting in blockages and ultimately reduced system efficiency or inability to deliver water and fertilizer to the soil or plants.

[0008] Several methods have been developed to increase the solubility of conventional fertilizers in high-pH irrigation water. U.S. Application No. 2016 / 0073578A1 discloses a fertigation method that includes adding an acidic fertilizer dissolving agent comprising a mineral acid to water and then dissolving the fertilizer in the water. However, this method requires a mixing step between the water and the acid, which may increase operating costs. Furthermore, direct handling of high-concentration mineral acids, including sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid, raises safety concerns. Furthermore, the reaction of the mineral acid with plant nutrients in the irrigation water may require readjustment of the final nutrient ratios in the fertigation solution, increasing the operating cost and time required to prepare an appropriate fertigation solution.

[0009] PCT Patent Application No. WO 2018 / 042312, Japanese Patent Application No. 2002 / 316888A, and Canadian Patent Application No. 2995400 each disclose granular fertilizer compositions comprising a fertilizer core and an outer coating comprising an inorganic acid. However, the high concentration of inorganic acid on the outer surface of the granular fertilizer can result in the absorption of atmospheric moisture, raising safety concerns regarding the handling of these granules and increasing the cost and complexity of keeping these fertilizer granules dry during storage.

[0010] During product formulation, the addition of large amounts of inorganic acid, such as 4% by weight or greater, to NPK (nitrogen-phosphorus-potassium) fertilizers can create operational problems and health hazards. Consequently, NPK fertilizers typically use less than 4% by weight of an inorganic acid, such as sulfuric acid, as described, for example, in Japanese Patent No. 2002 / 316888A. However, the addition of lower amounts of acid and / or diluted acid solutions can create other problems. For example, lower acid levels may not fully dissolve the NPK fertilizer in water. Furthermore, the additional addition of diluted acid solutions during fertilizer granulation can create operational problems, such as the formation of lumps and clumps in the fertilizer production system, which can pose challenges for large-scale production of acidified fertilizers. Summary of the Invention

[0011] Solutions to at least some of the above-mentioned problems associated with the preparation of acidified fertilizer compositions have been found. In particular, a method for preparing a plant fertilizer containing up to 40% by weight of inorganic acid has been found. The method comprises controlled addition of a concentrated inorganic acid solution, for example containing 50% by weight or more of acid, to a plant nutrient containing nitrogen (N), phosphorus (P) and optionally potassium (K). Preferably, the plant nutrients are provided in a granulator and the concentrated inorganic acid solution is added to the granulator at a controlled rate to form an acidified plant fertilizer composition containing solid acidified granules. As shown in Example 1 in a non-limiting manner, the method of the present invention results in relatively few lumps and clusters being formed and can be used to produce acidified fertilizer granules containing relatively large amounts of acid. Granulator devices used to produce plant fertilizers are typically lined internally with inorganic acid-resistant rubber. Therefore, with in the plant fertilizer production process, in the granulation front stage or the granulation back stage, add acid, for example the method for liquid acid is compared, and directly adding mineral acid to granulator can cause relatively less corrosion, for example to the corrosion of the equipment that is used for plant fertilizer production.In addition, in some embodiments, in the plant fertilizer production system, equipment or parts except granulator can not directly contact liquid acid.Therefore, the protection to these parts can be relatively less, with equipment or parts except granulator, also need to protect, for example, prevent the method for liquid acid corrosion with expensive protective layer and compare, and this is that method of the present invention provides economic advantage.

[0012] One aspect relates to a method for preparing a plant fertilizer containing solid acidic fertilizer granules. In some aspects, the method can be a batch process. The method, e.g., a batch process, can include any one, any combination, or all of steps (a) to (c). In step (a), plant nutrients containing nitrogen (N), phosphorus (P), and optionally potassium (K) can be provided in a container. In some aspects, the container can be a granulator. In some aspects, the container, e.g., a granulator, can be lined with an acid-resistant coating on the inside and / or can be made of an acid-resistant material. In some aspects, the acid-resistant coating and / or the container material can comprise acid-resistant rubber and / or plastic. In step (b), an acid solution containing a mineral acid can be fed at an average feed rate (MT acid·h) of 0.2 metric tons to 0.8 metric tons of mineral acid (MT acid) per metric ton of plant nutrients (MT nutrients) per hour (h). -1 MT nutrients -1 ) is fed into a container. In step (b), the inorganic acid and the plant nutrient can be contacted to obtain acidified granules having an average moisture content of 0.5% to 1.0% by weight. In step (c), the acidified granules can be dried to obtain dried acidic granules. In some aspects, the acidified granules can be dried in a dryer.

[0013] Container for mixing acid solution and plant nutrients, for example granulator and dryer can be identical or different containers. In some respects, acid solution can be fed to container within the duration of 1 hour to 5 hours. The acid solution feed rate in step (b) can comprise the first feed rate of the first duration and the second feed rate of the second duration that is different from the first feed rate, thereby forming the average feed rate of step (b). In some respects, the first feed rate can be 0.01MT acid·h -1 MT nutrients -1 Up to 0.25MT acid·h -1 MT nutrients -1 And / or the first duration can be 0.5h to 3h. In some aspects, the second feed rate can be 0.3MT acid·h -1 MT nutrients -1 To 1MT acid·h -1 MT nutrients -1 And / or the second duration may be 0.5h to 2h. The feed rate of the acid solution in step (b) may be 1MT acid per hour. -1 MT nutrients -1 To 3MT acid·h -1 MT nutrients -1 (MT acid·h -2 MT nutrients -1 ) is increased from a first feed rate to a second feed rate. In some aspects, a second plant nutrient can be added in step (b). The second plant nutrient can be the same as the plant nutrient or the dry acidic particles, for example, having a similar chemical composition, or the second plant nutrient can be different from the plant nutrient or the dry acidic particles, or can be a combination thereof. The weight ratio of the plant nutrient provided in step (a) to the second plant nutrient added in step (b) can be 1:1 to 5:1.

[0014] The acidified particles can be dried at a temperature of 55°C to 95°C, preferably 60°C to 80°C. In some cases, the drying step can change the particles from an amorphous solid, such as a paste, to a solid. The moisture content of the dried acidic particles can be 0.05% by weight to less than 1% by weight, preferably 0.05% by weight to 0.8% by weight. The average particle size of the dried acidic particles, such as diameter, can be 1mm to 4mm. In some aspects, the method can further include step (d), in which the dried acidic particles can be passed through a grading screen to obtain dried acidic particles of the desired particle size. In some aspects, at least a portion of the dried acidic particles having a particle size less than and / or greater than the desired particle size can be recycled to step (b), for example, step (b) of a subsequent batch. In some aspects, the dried acidic particles having a particle size greater than the desired particle size can be ground before being recycled to step (b). In some aspects, the desired particle size can be 1mm to 4mm. The process of the present invention results in relatively little lumps / agglomerates being formed, for example, 20 wt% or less of the acidified granules produced in step (b) form lumps / agglomerates having a size greater than 4 mm, and / or 10 wt% or less of the dried acidic granules produced in step (c) have a size greater than 4 mm.

[0015] The plant nutrient may comprise nitrogen (N): phosphorus (P): potassium (K) in a weight ratio of 5 to 20: 3 to 40: 0 to 30. In some aspects, the plant nutrient may comprise one or more N sources, one or more P sources, optionally one or more potassium (K) sources, optionally water, and optionally a binder. The optional binder may be triple superphosphate (TSP), guar gum, waxes such as paraffin, oils such as linseed oil and paraffin oil, flours and starches such as bleached wheat flour, gelatin, and / or polymers. In some specific aspects, the phytonutrient can comprise an N:P:K (NPK grade) in a weight ratio of about 7:19:12, about 9:25:7, about 10:5:10, about 18:18:0, about 13:13:13, about 10:19:10, about 10:10:20, about 8:15:8, about 11:6:17, about 8:8:23, about 10:10:10, about 8:5:26, about 6:16:6, about 6:29:6, about 10:5:15, about 11.5:11.5:11.5, about 18:9:9, about 8:26:8, about 12:12:12, about 12:30:0, about 7:34:0, or about 12:12:4. In some non-limiting examples, the term "about" is defined as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0.5%.

[0016] In some aspects, plant nutrients and / or the second plant nutrients can also include one or more than one other ingredients.Other ingredients can include preservatives, pesticides, fungicides, spices, fertilizers, plant growth agents, nutrients, trace elements, plant protection agents, fillers, micronutrients, secondary nutrients, flow promoters, adhesives, pH regulators or buffers etc., or any combination thereof. In some cases, plant nutrients and / or the second plant nutrients do not include one or more than one other ingredients.Plant nutrients can contain any amount of other ingredients, such as 0.001 weight % to 50 weight %, 0.001 weight % to 40 weight %, 0.001 weight % to 30 weight %, 0.001 weight % to 20 weight %, 0.01 weight % to 10 weight %, 0.01 weight % to 9 weight %, 0.01 weight % to 8 weight %, 0.01 weight % to 7 weight %, or any range or value therein. In some cases, the phytonutrient may contain 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0. ...10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35% or 40% by weight of other ingredients. The second phytonutrient can contain any amount of the other ingredients, such as 0.001% to 100% by weight, 0.001% to 90% by weight, 0.001% to 80% by weight, 0.001% to 70% by weight, 0.01% to 60% by weight, 0.001% to 50% by weight, 0.001% to 40% by weight, 0.001% to 30% by weight, 0.001% to 20% by weight, 0.01% to 10% by weight, 0.01% to 9% by weight, 0.01% to 8% by weight, 0.01% to 7% by weight, or any range or value therein.

[0017] Inorganic acid solution can be concentrated acid solution, for example, can contain 50 % by weight or higher than 50 % by weight, 60 % by weight or higher than 60 % by weight, 70 % by weight or higher than 70 % by weight, 80 % by weight or higher than 80 % by weight, 90 % by weight or higher than 90 % by weight or 95 % by weight or higher than 95 % by weight mineral acid. In some respects, mineral acid can be sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or its arbitrary combination, preferred sulfuric acid. In some respects, acid solution can contain 95 % by weight to 98 % by weight sulfuric acid.

[0018] In some cases, the method may further comprise coating the dry acidic granules of the desired particle size with a coating containing one or more water, one or more solubilizing agents, one or more binders, and / or one or more anti-caking agents to obtain coated fertilizer granules. In some cases, the coating does not contain an inorganic acid. In some cases, the coating may contain one or more binders and / or one or more anti-caking agents. In some cases, the water content of the coating may be less than 5% by weight of the coating. A coating with reduced water or moisture content may be considered a dry coating or dry coating. In some cases, the water content of the coating is 4%, 3%, 2%, 1%, or less than 1% by weight of the coating weight. The solubilizing agent may be Na2CO3, NaOH, KOH, Ca(OH)2, Mg(OH)2, and / or K2CO3. The binder may be triple superphosphate (TSP), guar gum, waxes such as paraffin, oils such as linseed oil and paraffin oil, flours and starches such as bleached wheat flour, gelatin and / or polymers. The anti-caking agent may be any known anti-caking agent such as surfactants, amines, liquid carriers such as oil and / or water, and / or the anti-caking agents provided by Kao Chemicals. Products such as In embodiments of the present invention, the coating layer may contain the ingredients in any concentration, ratio, weight percentage, volume percentage, etc.

[0019] In some cases, the methods may also include blending or compounding the plant fertilizer with other fertilizers.

[0020] On the one hand, relate to the plant fertilizer obtained by method of the present invention.Plant fertilizer can contain 2 weight % to 40 weight %, preferably 4 weight % to 36 weight %, more preferably 10 weight % to 35 weight % mineral acid.In some respects, mineral acid can be plant fertilizer weight, for example 2 weight %, 4 weight %, 6 weight %, 8 weight %, 10 weight %, 12 weight %, 14 weight %, 16 weight %, 18 weight %, 20 weight %, 22 weight %, 24 weight %, 26 weight %, 28 weight %, 30 weight %, 32 weight %, 34 weight %, 36 weight %, 38 weight % or 40 weight % or its any scope of fertilizer granules.The limiting examples of mineral acid can comprise sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or its arbitrary combination.In some particular aspects, mineral acid can be sulfuric acid. In some aspects, the plant fertilizer can comprise nitrogen (N):phosphorus (P):potassium (K):sulfur (S) in a weight ratio of 5 to 20:3 to 40:0 to 30:3 to 25. In some specific aspects, the plant fertilizer can have a weight ratio of about 7:19:12:15, about 7:19:12:10, about 9:25:7:8, about 10:5:10:10, about 18:18:0:6, about 13:13:13:11, about 10:19:10:10, about 10:10:20:13, about 8:15:8:9, about 11:6:17:12, about 8:8:23:14, about 10:10:10:10, The fertilizer may also include an N:P:K:S (nitrogen:phosphorus:potassium:sulfur) ratio of about 8:5:26:15, about 6:16:6:8, about 6:29:6:8, about 10:5:15:12, about 11.5:11.5:11.5:9.8, about 18:9:9:9, about 8:26:8:9, about 12:12:12:10, about 12:30:0:6, about 7:34:0:6, or about 12:12:4:8 (NPKS grade or NPK+S grade). In some non-limiting examples, the term "about" is defined as a deviation within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or 0.5%. The plant fertilizer may optionally contain one or more other ingredients.

[0021] The plant fertilizer may comprise solid acidic fertilizer granules, for example, dry acidic granules having an average crush strength of 2 kg / granule to 10 kg / granule, or 3 kg / granule to 7 kg / granule, or 4 kg / granule to 6 kg / granule. When 10 grams of the plant fertilizer is dissolved in 100 ml of water under ambient conditions, the plant fertilizer may form a solution having a pH of less than 4, preferably less than 3.5, more preferably less than 3, for example, 1 to 3, wherein the pH of the water is 7 or greater before the plant fertilizer is dissolved in the water. In some cases, the plant fertilizer may comprise an effective amount of a mineral acid sufficient to form a solution having a pH of less than 3.5, less than 3, less than 2.5, less than 2, less than 1.5, or less than 1. In some cases, the plant fertilizer may comprise an effective amount of a mineral acid sufficient to form a solution when up to 9 grams, up to 8 grams, up to 7 grams, up to 6 grams, up to 5 grams, up to 4 grams, up to 3 grams, up to 2 grams, or up to 1 gram of the solid fertilizer granules are dissolved. In some cases, the plant fertilizer can be dissolved in at least 150 ml, at least 200 ml, at least 300 ml, at least 400 ml, at least 500 ml, at least 600 ml, at least 700 ml, at least 800 ml, at least 900 ml, at least 1000 ml, at least 2000 ml, or at least 3000 ml of water to form a solution. In some cases, the pH of the water is greater than 7.5, greater than 8.0, greater than 8.5, greater than 9.0, greater than 9.5, greater than 10.0, greater than 10.5, greater than 11.0, or greater than 11.5, etc., before the plant fertilizer is dissolved in the water. In some aspects, the water can contain at least 50 ppm of calcium (Ca 2+ ppm, at least 200 ppm, at least 250 ppm, at least 300 ppm, at least 350 ppm, at least 400 ppm, at least 450 ppm, at least 500 ppm, at least 550 ppm, at least 600 ppm, at least 650 ppm, at least 700 ppm, at least 750 ppm, at least 800 ppm, at least 850 ppm, at least 900 ppm, at least 950 ppm, at least 1000 ppm, at least 1500 ppm, at least 2000 ppm, at least 2500 ppm, at least 3000 ppm, at least 3500 ppm, or at least 4500 ppm, etc., of calcium.

[0022] Also disclosed within the scope of the present invention are fertilizer blends or compound fertilizers containing plant fertilizers, such as fertilizer granules, prepared according to the methods of the present invention and other fertilizers. The other fertilizers may be, but are not limited to, nitrogen and phosphorus (NP), phosphorus and potassium (PK), nitrogen and phosphorus and potassium (NPK), urea, diammonium phosphate (DAP), monoammonium phosphate (MAP), single superphosphate (SSP), triple superphosphate (TSP), or combinations thereof. In one aspect, the other fertilizers may include an inorganic acid. However, in other aspects, the other fertilizers do not include an inorganic acid.

[0023] Also disclosed within the scope of the present invention are methods of fertigation. In some aspects, the method of fertigation can include combining solid acidic fertilizer granules or a fertilizer blend with water to form a fertigation solution having a pH less than 4. In some cases, the method optionally includes combining the fertigation solution with additional water to form a fertilizer solution. In some cases, the method optionally includes applying the fertigation solution or the fertilizer solution to crops. In some aspects of the present invention, the combination of fertilizer granules and water reduces the pH of the water from 4 or greater than 4 to less than 4, less than 3.5, less than 3, less than 2.5, less than 2, less than 1.5, or less than 1. In some cases, the combination of the fertilizer granules and water reduces the pH of the water from 6.5 or greater, 7.0 or greater, 7.5 or greater, 8.0 or greater, 8.5 or greater, 9.0 or greater, 9.5 or greater, 10.0 or greater, 10.5 or greater, 11.0 or greater, 11.5 or greater, or 6.5 to 11.5, or greater than 7.0 to 10, or greater than 7.0 to 9, or greater than 7.0 to 8.5 to less than 4. In one aspect, the applying step can include applying the fertigation solution or fertilization solution to at least one of soil, an organism, a crop, a liquid carrier, a liquid solvent, or a combination thereof. Applying the fertigation solution or fertilization solution can promote plant growth and / or plant health.

[0024] In some aspects, the water used to form the fertigation solution or fertilizer solution can contain at least 50 ppm calcium (Ca 2+ In some cases, the water contains more than 100 ppm of calcium (Ca 2+ ), more than 200 ppm calcium, more than 300 ppm calcium, more than 400 ppm calcium, more than 500 ppm calcium, more than 600 ppm calcium, more than 700 ppm calcium, more than 800 ppm calcium, more than 900 ppm calcium, more than 1000 ppm calcium, more than 1500 ppm calcium, more than 2000 ppm calcium, more than 2500 ppm calcium, more than 3000 ppm calcium, more than 3500 ppm calcium or more than 4000 ppm calcium. In some aspects, the water comprises at least 50 ppm to 1000 ppm of Ca2+ , or at least 50ppm to 500ppm of Ca 2+ , or at least 50ppm to 250ppm of Ca 2+ , or at least 50ppm to 150ppm Ca 2+ .

[0025] Included below are definitions of various terms and phrases used throughout this specification.

[0026] The term "fertilizer" is defined as a substance applied to soil or plant tissue to provide one or more plant nutrients necessary or beneficial to plant growth and / or a stimulant or promoter that increases or promotes plant growth. Non-limiting examples of fertilizers include substances with one or more urea, ammonium nitrate, calcium ammonium nitrate, one or more superphosphate, binary NP fertilizers, binary NK fertilizers, binary PK fertilizers, NPK fertilizers, molybdenum, zinc, copper, boron, cobalt and / or iron. In some aspects, fertilizers include agents that promote plant growth and / or enhance the ability of plants to benefit from fertilizers, such as, but not limited to, biostimulants, urease inhibitors and nitrification inhibitors. In some specific cases, the fertilizer is urea, such as urea granules.

[0027] The terms "about" or "approximately" and "substantially" are defined as close to as understood by one of ordinary skill in the art. In a non-limiting example, these terms are defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0028] The terms "wt %," "volume %," or "mole %" refer to the weight percent, volume percent, or mole percent of a constituent based on the total weight, total volume, or total moles of the substance in which the constituent is contained, respectively. In a non-limiting example, 10 grams of a constituent in 100 grams of a substance is 10% by weight of the constituent.

[0029] In the claims or description, when used in combination with any of the terms "comprises," "includes," "contains," or "has," "one" may be expressed without using a quantifier, but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one."

[0030] The words "comprising," "having," "including," or "containing" are inclusive or open-ended and do not exclude the presence of additional, unrecited elements or method steps.

[0031] The compositions and methods of the present invention may "comprise," "consist essentially of," or "consist of" the specific ingredients, components, and compositions disclosed throughout this specification. With respect to the transition phrase "consist essentially of," in one non-limiting aspect, the basic and novel feature of the solid acidic fertilizer of the present invention is that the solid acidic fertilizer contains an inorganic acid distributed throughout the solid fertilizer particles.

[0032] Other objects, features, and advantages of the present invention will become apparent from the following drawings, detailed description, and examples. However, it should be understood that the drawings, detailed description, and examples, while indicating specific embodiments of the present invention, are given by way of illustration only and are not intended to be limiting. Furthermore, from this detailed description, it will be apparent to those skilled in the art that variations, combinations, and modifications within the spirit and scope of the present invention will become apparent.

[0033] In the context of the present invention, at least the following 20 aspects are described.

[0034] Aspect 1 relates to a method for preparing a plant fertilizer comprising solid acidic fertilizer granules, the method comprising:

[0035] (a) Providing plant nutrients comprising nitrogen (N), phosphorus (P), and optionally potassium (K) in a container.

[0036] (b) feeding an acid solution comprising a mineral acid at an average feed rate of 0.2 to 0.8 metric tons of mineral acid (MT acid) per metric ton of plant nutrients (MT nutrients) per hour (MT acid·h -1 MT nutrients -1 ) into the container at a feed rate to contact the inorganic acid and the plant nutrients to obtain acidified particles having an average moisture content of 0.5% to 1.0% by weight; and

[0037] (c) drying the acidified granules to obtain dry acidic granules.

[0038] Aspect 2 relates to the method of aspect 1, wherein in step (b), the acid solution comprising the inorganic acid is fed into the container for a duration of 1 to 5 hours.

[0039] Aspect 3 relates to the method of aspect 1 or 2, wherein the feed rate in step (b) comprises 0.01 MT acid·h -1 MT nutrients -1 Up to 0.25MT acid·h -1 MT nutrients -1 The first feed rate and the second duration are 0.3 MT acid·h -1 MT nutrients -1 To 1MT acid·h -1MT nutrients -1 The second feed rate.

[0040] Aspect 4 relates to the method of aspect 3, wherein the first duration is from 0.5 hours to 3 hours, and / or the second duration is from 0.5 hours to 2 hours.

[0041] Aspect 5 relates to the method of aspect 3 or 4, wherein the feed rate is 1MT acid per hour. -1 MT nutrients -1 (MT acid·h -2 MT nutrients -1 ) to 3MT acid·h -2 MT nutrients -1 The rate of change increases from the first feed rate to the second feed rate.

[0042] Aspect 6 relates to the method of any one of aspects 1 to 5, wherein step (b) further comprises adding a second plant nutrient, wherein the second plant nutrient is the same as the plant nutrient, the same as the dry acidic particles, or different from the plant nutrient and the dry acidic particles, or a combination thereof.

[0043] Aspect 7 relates to the method of aspect 6, wherein the weight ratio of the phytonutrient to the second phytonutrient is 1:1 to 5:1.

[0044] Aspect 8 relates to the method of any one of aspects 1 to 7, wherein the plant nutrients comprise nitrogen (N):phosphorus (P):potassium (K) in a weight ratio of 5 to 20:3 to 40:0 to 30.

[0045] Aspect 9 relates to the method of any one of aspects 1 to 8, wherein the plant nutrient and / or the second plant nutrient consists of one or more N sources, one or more P sources, optionally one or more potassium K sources, optionally water, and optionally a binder.

[0046] Aspect 10 relates to the method of any one of aspects 1 to 9, wherein the inorganic acid is sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or any combination thereof, preferably sulfuric acid.

[0047] Aspect 11 relates to the method of any one of aspects 1 to 10, wherein the acid solution comprises 95% to 98% by weight of sulfuric acid.

[0048] Aspect 12 relates to the method of any one of aspects 1 to 11, wherein the acidified particles are dried at a temperature of 55°C to 95°C, preferably 60°C to 80°C.

[0049] Aspect 13 relates to the method of any one of aspects 1 to 12, wherein the dried acidic particles have a moisture content of 0.05 wt% to less than 1 wt%, preferably 0.05 wt% to 0.8 wt% and / or an average particle size distribution of 1 mm to 4 mm.

[0050] Aspect 14 relates to the method of any one of aspects 1 to 13, wherein the method further comprises:

[0051] (d) passing the dried acidic granules through a sizing screen to obtain dried acidic granules of a desired particle size.

[0052] Aspect 15 relates to a plant fertilizer comprising solid acidic fertilizer granules obtained by the method according to any one of aspects 1 to 14.

[0053] Aspect 16 relates to the plant fertilizer of Aspect 15, wherein the plant fertilizer comprises 2% to 40% by weight, preferably 4% to 36% by weight, more preferably 10% to 35% by weight of inorganic acid and / or wherein the plant fertilizer comprises nitrogen (N): phosphorus (P): potassium (K): sulfur (S) in a weight ratio of 5 to 20:3 to 40:0 to 30:3 to 25.

[0054] Aspect 17 relates to the plant fertilizer according to any one of aspects 15 to 16, wherein the average crushing strength of the solid acidic fertilizer granules is 2 kg / granule to 10 kg / granule, or 3 kg / granule to 7 kg / granule, or 4 kg / granule to 6 kg / granule.

[0055] Aspect 18 relates to the plant fertilizer of any one of aspects 15 to 17, wherein the solid acidic fertilizer granules are capable of forming a solution having a pH of less than 4, preferably less than 3, when 10 grams of the plant fertilizer is dissolved in 100 ml of water under ambient conditions, wherein the pH of the water is 7 or greater before the plant fertilizer is dissolved in the water.

[0056] Aspect 19 relates to the plant fertilizer according to any one of aspects 15 to 18, wherein the plant fertilizer is contained in a fertilizer blend or compound fertilizer comprising the plant fertilizer and other fertilizers.

[0057] Aspect 20 relates to a fertilization method, comprising applying the plant fertilizer prepared according to any one of the methods of aspects 1 to 14 or the plant fertilizer according to any one of aspects 15 to 19 to at least a portion of soil, a crop, or soil and a crop. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Advantages of the present invention will become apparent to those skilled in the art upon benefit of the following non-limiting detailed description and with reference to the accompanying drawings, which may not be drawn to scale.

[0059] Figure 1is a schematic diagram depicting an exemplary method of making an acidified plant fertilizer according to a non-limiting embodiment of the present invention.

[0060] Figure 2 is a schematic diagram depicting an exemplary method of using an acidified plant fertilizer according to a non-limiting embodiment of the present invention in fertigation.

[0061] Figure 3 is a scanning electron microscope (SEM) image of an exemplary acidified NPK fertilizer granule. DETAILED DESCRIPTION

[0062] A method for preparing solid acidic fertilizer granules containing plant fertilizer has been discovered. The method comprises controlled addition of a concentrated mineral acid solution, e.g., containing 50% by weight or greater than 50% by weight of mineral acid, to a plant nutrient containing nitrogen (N), phosphorus (P), and optionally potassium (K). The concentrated mineral acid solution can be contacted with the plant nutrient at a controlled rate to form an acidified plant fertilizer composition containing up to 40% by weight of mineral acid. As shown in a non-limiting manner in Example 1, the method of the present invention can produce solid acidic fertilizer granules with a high mineral acid content. The method can result in relatively little lumps or clusters, e.g., less than 10% by weight of the solid acidic granules produced before screening have a particle size greater than 4 mm.

[0063] These and other non-limiting aspects of the present invention are discussed in more detail in the following sections with reference to the accompanying drawings.

[0064] A. Method for preparing solid acidic fertilizer granules

[0065] Reference Figure 1 , describes a non-limiting method 100 for preparing a plant fertilizer containing solid acidic fertilizer particles. The method 100 can be a batch process. The method 100 can include steps 101, 102, 103, and 104.

[0066] In step 101, plant nutrients containing nitrogen (N), phosphorus (P), and optionally potassium (K) may be provided to a container.

[0067] In step 102, an acid solution containing a mineral acid can be provided to the container, and the mineral acid and the plant nutrients can contact in the container to form acidified particles. The moisture content of the acidified particles can be from 0.5 % by weight to 1 % by weight, or at least one of 0.5 % by weight, 0.6 % by weight, 0.7 % by weight, 0.8 % by weight, 0.9 % by weight and 1 % by weight, equal to any one or between any two. In some aspects, for batch processing, the acid solution can continue for 1 hour to 5 hours or continue for 1 hour, 2 hours, 3 hours, 4 hours and 5 hours, equal to any one or between any two and be fed to the container. The acid solution can be fed at a rate of 100 metric tons of plant nutrients (MT nutrients) per hour. -1 ), such as plant nutrients provided in containers, 0.2 metric tons to 0.8 metric tons of inorganic acid (MT acid), (MT acid·h -1 MT nutrients -1 ) or 0.2MT acid·h -1 MT nutrients -1 、0.3MT acid·h -1 MT nutrients -1 、0.4MT acid·h -1 MT nutrients -1 、0.5MT acid·h -1 MT nutrients -1 ,0.6MT acid·h -1 MT nutrients -1 、0.7MT acid·h -1 MT nutrients -1 and 0.8MT acid·h -1 MT nutrients -1 In some aspects, in step 102, the acid may be fed at a first feed rate for a first duration and at a second feed rate for a second duration. In some aspects, the first feed rate may be 0.01 MT acid h -1 MT nutrients -1 Up to 0.25MT acid·h -1 MT nutrients -1 , or 0.01MT acid·h -1 MT nutrients -1 、0.05MT acid·h -1 MT nutrients -1 、0.1MT acid·h -1 MT nutrients -1 、0.15MT acid·h -1 MT nutrients -1 、0.2MT acid·h -1 MT nutrients -1and 0.25MT acid·h -1 MT nutrients -1 In some aspects, the second feed rate may be 0.25 MT acid·h -1 MT nutrients -1 To 1MT acid·h -1 MT nutrients -1 , or 0.3MT acid·h -1 MT nutrients -1 To 1MT acid·h -1 MT nutrients -1 , or 0.25MT acid·h -1 MT nutrients -1 、0.3MT acid·h -1 MT nutrients -1 、0.4MT acid·h -1 MT nutrients -1 、0.5MT acid·h -1 MT nutrients -1 ,0.6MT acid·h -1 MT nutrients -1 、0.7MT acid·h -1 MT nutrients -1 , 0.8MT acid·h -1 MT nutrients -1 , 0.9MT acid·h -1 MT nutrients -1 and 1MT acid·h -1 MT nutrients -1 In some aspects, the feed rate of the acid solution can be increased from the first feed rate to the second feed rate at a rate of 1 MT acid·h -2 MT nutrients -1 To 3MT acid·h -2 MT nutrients -1 Or 1MT acid·h -2 MT nutrients -1 、1.5MT acid.h -2 .MT nutrients -1 、2MT acid·h -2 MT nutrients -1、2.5MT acid·h -2 MT nutrients -1 and 3MT acid·h -2 MT nutrients -1 at least one of, equal to any one of, or between any two of. In some aspects, a second plant nutrient can be fed into the container in step 102. The second plant nutrient can be the same as the plant nutrient, for example, having the same chemical composition as the plant nutrient, or the same as the dried acidified particles, for example, having a particle size that is smaller and / or larger than the particle size desired for the previous batch of dried acidified particles, or different from the plant nutrients or the dried acidified particles, or a combination thereof. The second plant nutrient can be added to step 102 at a weight ratio of plant nutrients to second plant nutrients of 1:1 to 5:1 or 1:1, 2:1, 3:1, 4:1 and 5:1, or any ratio therebetween. In some aspects, in step 102, the plant nutrients, acid solution and / or second plant nutrients can be heated during mixing or preheated prior to mixing. In some cases, the ingredients can be heated to room temperature or up to 90°C or above. In some cases, 20% by weight or less of the acidified particles produced in step 102 form agglomerates / lumps having a particle size greater than 4 mm.

[0068] In step 103, the acidified granules can be dried to form dried acidified granules, such as solid acidic fertilizer granules. The moisture content of the dried acidified granules can be from 0.05% to less than 1% by weight, preferably from 0.05% to 0.8% by weight, or at least one of, or equal to, or between any two of, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and less than 1% by weight. The average particle size of the dried acidified granules can be from 1 mm to 4 mm. The drying in step 103 can be carried out at a temperature of 55°C to 95°C, or 60°C to 80°C, or at least one of, or equal to, or between any two of, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, and 95°C.

[0069] In step 104, the dried acidified particles can be passed through a sizing screen to obtain particles of a desired particle size. In some aspects, dried acidified particles having a particle size smaller and / or larger than the desired particle size can be recycled to step 102, such as a subsequent batch of step 102. The acidified particles to be recycled can be ground and recycled to step 102.

[0070] As described above, the addition of acid at a controlled rate in step 102 results in relatively little clump or lump formation. In some aspects, 10% by weight or less of the dried, acidified particles produced in step 103, for example, before passing the particles through a sizing screen, can have a particle size greater than 4 mm. In some aspects, 20% by weight or less, such as 10% to 20% by weight, of the acidified particles produced in step 102, for example, before drying, can have a particle size greater than 4 mm.

[0071] In some aspects, the container in step 101 can be a granulator. In some aspects, the container, for example, granulator, can be lined with acid-resistant coating and / or can be made of acid-resistant material inside. In some aspects, acid-resistant coating and / or container material can comprise acid-resistant rubber and / or plastics. The plant nutrients in the form of powder, granule, pellet and / or pill can be provided to the container. In some aspects, the plant nutrients in the form of particles with an average particle size of 1mm to 4mm can be provided to the container. The acid solution can contain at least one of 50% by weight to 98% by weight or 50% by weight, 55% by weight, 60% by weight, 65% by weight, 70% by weight, 75% by weight, 80% by weight, 85% by weight, 90% by weight, 95% by weight, 98% by weight, equal to any one or any two of the inorganic acid. The inorganic acid can be sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or its arbitrary combination, preferably sulfuric acid. In some aspects, the acid solution can contain 95% to 98% sulfuric acid by weight, or at least one of 95%, 96%, 97%, and 98%, or equal to or between any two of these. The acidified particles can be dried in a dryer. Steps 101 and 102 can be performed in the same container or in different containers.

[0072] In some aspects, method 100 can optionally include the addition of other additives. Other additives can be added i) with the plant nutrients in step 101, ii) in step 102, for example, as a second nutrient or with a second plant nutrient and / or separately, and / or iii) after the acidified granules and / or dried acidic granules are formed. Other additives can include, but are not limited to, secondary nutrients, one or more trace elements, one or more anti-caking agents, water, one or more pigments, or combinations thereof. Non-limiting examples of anti-caking agents include surfactants, amines, liquid carriers, such as oils and / or water, and / or provided by Kao Chemicals (Kao Corporation, Japan) Products such as In some aspects, other additives may be added at less than 5 weight percent of the total weight of the phytonutrients.

[0073] In some aspects, the method (100) can optionally include applying a layer, or a second layer, a third layer, a fourth layer, or more than four layers onto the dried acidic fertilizer granules. These layers can be, but are not limited to, one or more micronutrients, macronutrients, secondary nutrients, fertilizers, water, one or more solubilizers, one or more binders, and / or one or more anti-caking agents (not shown). For each layer, the amount of time used for coating can be an amount sufficient to ensure that a substantially uniform layer is formed on the core and / or on subsequent layers. In some cases, the application time can include 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or more than 5 hours, or any range therebetween, such as 5 minutes to 5 hours, 5 minutes to 1 hour, etc. In some cases, the ingredients are heated to room temperature or up to 90° C. or above.

[0074] In some aspects, the method (100) can optionally include combining other fertilizers with the dried acidic fertilizer granules to form a blended fertilizer or compound fertilizer (104). The combining can be performed using any type of mixing or stirring equipment commonly available in the art, such as, for example, a WJ-700, WJ-900, or WJ-1000 mixer from Whirlston Machinery (Zhengzhou, China). Once combined, the fertilizer blend can be stored for future use or sold.

[0075] In some cases, the solid acidic fertilizer granules are produced on an industrial scale. In some cases, the production rate of the solid acidic fertilizer granules is 1 kg / hour or less, or up to 10,000 kg / hour or more.

[0076] B. Acidic plant fertilizer

[0077] The acidic plant fertilizers of the present invention can comprise solid acidic fertilizer particles, such as dried acidic particles. Acidic plant fertilizers, for example, solid acidic fertilizer particles of the present invention, can comprise phosphorus, nitrogen, an inorganic acid, and optionally potassium. In some aspects, the plant fertilizer can include secondary nutrients, one or more trace elements, one or more anti-caking agents, water, one or more pigments, or a combination thereof. Non-limiting examples of anti-caking agents include surfactants, amines, liquid carriers such as oils and / or water, and / or the like provided by Kao Chemicals (Kao Corporation, Japan). Products such as

[0078] In some embodiments, the solid acidic fertilizer granules may contain at least 50% by weight or more than 50% by weight of plant nutrients containing N, P, and optionally K, based on the total weight of the solid acidic fertilizer granules. The solid acidic fertilizer granules may contain at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100% by weight, or any concentration therebetween of plant nutrients based on the total weight of the solid acidic fertilizer granules. The plant nutrients may form the bulk of the granules. In this specification, when referring to solid acidic fertilizer granules, the terms bulk, matrix, and network may be used interchangeably. The inorganic acid may be evenly distributed throughout the various portions of the granules. The solid acidic fertilizer granules may contain 2% to 40% by weight, preferably 4% to 36% by weight, and more preferably 10% to 35% by weight of the inorganic acid.

[0079] It is contemplated that the fertilizer granules of the present invention may include any number of the ingredients discussed in this specification. The granules may also include any number of combinations of the other ingredients described in this specification. The concentration of any ingredient within the composition may vary. In non-limiting embodiments, for example, the composition in its final form may comprise, consist essentially of, or consist of, for example, at least about 0.0001%, 0.0010%, 0.0020%, 0.0040%, 0.0050%, 0.0060%, 0.0070%, 0.0080%, 0.0090%, 0.0100%, 0.0200%, 0.0300%, 0.0400%, 0.0500%, 0.0600%, 0.0700%, 0.0800%, 0.0900%, 0.1000%, 0.200 %, 0.5000%, 0.6000%, 0.7000%, 0.8000%, 0.9000%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 9.0%, 10%, 20%, 30%, 35%, 40%, 45%, 50%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, 100%, or any range or concentration therebetween of at least one ingredient mentioned throughout the specification and claims. In non-limiting aspects, the percentages can be calculated by weight or volume of the total composition. One of ordinary skill in the art will appreciate that concentrations can vary depending on the addition, substitution, and / or deletion of ingredients in a particular composition.

[0080] In some aspects, the solid acidic fertilizer granules can include a coating comprising one or more water, one or more solubilizing agents, one or more binders, and / or one or more anti-caking agents. In some cases, the water content of the coating can be less than 5% by weight of the coating and be considered a dry or dry coating. In some cases, the water content of the coating is less than 4%, 3%, 2%, or 1% by weight of the coating. In some aspects, the coating of the acidic fertilizer granules does not contain an inorganic acid. In some aspects, the coating can contain one or more pigments. In some aspects, the solid acidic fertilizer granules of the present invention can include any amount, volume, thickness, coverage of the fertilizer granule surface, etc. of the coating. In some cases, the coating is 0.001% to 10% by weight, 0.001% to 9% by weight, 0.001% to 8% by weight, 0.001% to 7% by weight, 0.001% to 6% by weight, 0.01% to 10% by weight, 0.1% to 10% by weight, 0.5% to 10% by weight, 0.5% to 9% by weight, 0.5% to 8% by weight, 0.5% to 7% by weight, 0.5% to 6% by weight, 1% to 6% by weight, or any range therebetween, of the total weight of the coated solid acidic fertilizer granules, or any range therebetween. In some aspects, at least a portion of the surface of the solid acidic fertilizer granules can be in direct contact with the coating. In some cases, the coating is not dispersed throughout the fertilizer granules. In some cases, the coating forms a shell that at least partially coats the granules. The coating may coat at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% or more of the particle surface. The particles may be coated with a coating that reduces water dissolution into the core compared to particles without the coating. In some cases, the coating has an average thickness of 2 μm to 70 μm, 2 μm to 20 μm, 20 μm to 50 μm, or 10 μm to 40 μm, or any range or thickness therebetween.

[0081] Solid acid fertilizer of the present invention can be included in fertilizer composition with other fertilizers. In some cases, solid acid fertilizer is included in blended fertilizer composition or compound fertilizer. Other fertilizers can be selected according to the special needs of certain types of soil, climate or other growth conditions to improve the efficacy of blended composition in promoting plant growth and crop yield to the greatest extent. The solid acid fertilizer here can be blended with other fertilizers with any concentration. In some cases, the desired concentration is enough to meet the content of nutrients or micronutrients needed in the blend. For example, blended fertilizer composition of the present invention can be formulated into quick release fertilizer. Or, blended fertilizer composition can be formulated into slow release fertilizer. In some cases, blended fertilizer composition is formulated into specialty fertilizer.

[0082] C. Fertigation method using solid acid fertilizer granules

[0083] Reference Figure 2 A non-limiting fertigation method (200) using solid acidic fertilizer granules can include combining the solid acidic fertilizer granules with water to form a fertigation solution (201) having a pH of less than 4. In some aspects, optionally, the method (200) can include combining the fertigation solution with additional water to form a fertilizer solution (202). In some aspects, the method (200) can include applying the fertigation solution or the fertilizing solution to a crop (203). In some aspects, applying (203) can include adding the fertigation solution or the fertilizing solution to an irrigation system and applying the fertigation solution or the fertilizing solution to the soil and / or plants via irrigation.

[0084] Non-limiting examples of plants that can benefit from fertilizer of the present invention include lianas, trees, shrubs, stalked plants, ferns, etc. Plants can include orchard crops, lianas, ornamental plants, food crops, timber, and the plants harvested. Plants can include gymnosperms, angiosperms, and / or ferns. Gymnosperms include plants from Araucariaceae, Cupressaceae, Pinaceae, Podocarpaceae, Pinaceae, Taxaceae, Cycadaceae, and Ginkgoaceae. Angiosperms may include plants from the family Aceraceae, Agavaceae, Anacardiaceae, Annonaceae, Apocynaceae, Aquifoliaceae, Araliaceae, Arecaceae, Diploceae, Asteraceae, Berberidaceae, Betulaceae, Bignoniaceae, Kapokaceae, Boraginaceae, Oleaceae, Boxwood Family, Cinnamomum Camphoraceae, Cannabaceae, Caprifoliaceae, Carica Papayaceae, Casuarina Family, Celastraceae, Cercidiphyllum Family, Theobroma Cumbuaceae, Garcinia Family, Combretaceae, Cornaceae, Tanaceae, Catalpa Family, Diospyros Family, Elaeagnaceae, Ericaceae, Euphorbiaceae, Fabaceae, Fagaceae, Ribes Family, Hamamelidaceae, Aesculus Family, Illicaceae, Juglandaceae, Lauraceae, Barnyardgrass Family, Lythrum Family, Magnoliaceae, Malvaceae, Malvaceae , Melastomataceae, Meliaceae, Moraceae, Moringaceae, Mendingaceae, Cyperaceae, Myricaceae, Myrsinaceae, Myrtaceae, Cyclobalanopsisaceae, Mirabilis jalapa, Davidiaceae, Aspergillusaceae, Oleaceae, Oxalidaceae, Pandanaceae, Papaveraceae, Phyllanthaceae, Pittosporaceae, Platanaceae, Poaceae, Polygonaceae, Proteaceae, Punicaceae, Rhamnaceae, Rhizophoraceae, Rosaceae, Rubiaceae, Rutaceae, Salicaceae, Sapindaceae, Sapotaceae, Simacariaceae, Solanaceae, Sterculiaceae, Strelitziaceae, Styracaceae, Merantiaceae, Asteraceae, Tamarixaceae, Theaceae, Pseudo-rotundaceae, Thymelaeaceae, Tiliaceae, Ulmaceae, Verbenaceae and / or Vitaceae.

[0085] Example

[0086] The present invention will be described in more detail by specific examples. The following examples are provided for illustrative purposes only and are not intended to limit the present invention in any way. Those skilled in the art will readily recognize various noncritical parameters that can be changed or modified to produce substantially the same result.

[0087] Although the embodiments of the present application and advantages thereof have been described in detail, it should be understood that various changes, substitutions and modifications may be made herein without departing from the spirit and scope of the embodiments defined by the appended claims. In addition, the scope of the present application is not intended to be limited to the specific embodiments of the processes, machines, manufactures, compositions of matter, devices, methods and steps described in the specification. As will be readily understood by those skilled in the art from the foregoing disclosure, processes, machines, manufactures, compositions of matter, devices, methods or steps that currently exist or will be developed later for performing functions substantially the same as those of the corresponding embodiments described herein or achieving substantially the same results may be utilized. Therefore, the appended claims are intended to include these processes, machines, manufactures, compositions of matter, devices, methods or steps within their scope.

[0088] Example 1

[0089] Preparation of acidic fertilizer granules with controlled acid addition

[0090] In an embodiment of the present invention (experiment 1), a batch process was used to prepare an acidified plant fertilizer containing solid acidic fertilizer granules. A plant nutrient feed containing nitrogen (N), phosphorus (P) and potassium (K) in a weight ratio of 11:29:19 (Table 1) was fed into a granulator. 4 to 10 tons of plant nutrients were fed into the granulator. An acid solution containing 98% by weight of sulfuric acid was fed into the granulator. The acid solution in the granulator contacted and mixed with the plant nutrients, and acidified granules were produced from the mixture of the acid solution and the plant nutrients. The acid solution was initially added to the granulator at a rate of 0.75 metric tons (MT) per hour. The acid solution was added at a first rate for 0.5 to 3 hours. The addition rate of the acid solution was then increased from the first rate to a second rate of 2.5 to 3.5 MT per hour. The acid solution was added at a second rate for 0.5 to 2 hours. The wettability of the acid solution and the plant nutrient mixture was monitored, and the acid addition rate was controlled to avoid excessive wetting. The moisture content of the acidified granules produced was controlled to be less than 1% by weight. The acidified granules were produced in the granulator at a temperature of 20°C to 45°C. The acidified granules were discharged from the granulator at a temperature of 40°C to 45°C and then dried in a dryer at 65°C to 70°C to form dried acidified granules. Less than 20% by weight of the acidified granules formed lumps or agglomerates with a particle size greater than 4 mm at the discharge / outlet of the granulator. Less than 10% by weight of the dried acidified granules formed had a particle size greater than 4 mm. The dried acidified granules produced contained N:P:K:S in a weight ratio of 7:19:12:15 (Table 1). Figure 3 An SEM image of the produced dried acidified granules is shown. The average crush strength of the dried acidified granules was 5.1 kg / granule. 10 grams of the dried acidified granules completely dissolved in 90 grams of water at 20°C, resulting in a 100 gram solution with a pH of 2.27.

[0091] Table 1: Phytonutrients

[0092]

[0093] A comparative experiment was conducted. In this comparative experiment, a process and parameters similar to those in Experiment 1 were used, except that the rate of acid addition to the granulator was different. In this comparative experiment, acid was added to the granulator at a constant rate of 2.5 to 3.5 metric tons per hour for 1 to 5 hours. In this experiment, 10 to 15 percent by weight of the dried, acidified granules formed after drying had a particle size greater than 4 mm. A comparison of Experiment 1 and the comparative experiment demonstrates that the method of the present invention results in less lumps or agglomerates.

Claims

1. A method for preparing a plant fertilizer comprising solid acidic fertilizer granules having from greater than 10% to 40% by weight of an inorganic acid uniformly distributed throughout the solid acidic fertilizer granules, the method comprising: (a) providing plant nutrients comprising nitrogen, phosphorus, and optionally potassium in a container; (b) an acid solution containing an inorganic acid is added at a rate of 0.01 MT of the acid solution·h for a first duration. -1 MT phytonutrients -1 Up to 0.25MT acid solution·h -1 MT phytonutrients -1 The first feed rate and the second duration are 0.25MT acid solution·h -1 MT phytonutrients -1 To 1MT acid solution·h -1 MT phytonutrients -1 feeding the inorganic acid and the plant nutrient into the container at a second feed rate, wherein the second feed rate is greater than the first feed rate, so as to contact the inorganic acid and the plant nutrient to obtain acidified particles having an average moisture content of 0.5% to 1.0% by weight; as well as (c) drying the acidified granules to obtain dry acidic granules having from greater than 10% to 40% by weight of the inorganic acid uniformly distributed throughout the dry acidic granules.

2. The method according to claim 1, wherein in step (b), the acid solution comprising the inorganic acid is fed into the container for a total duration of 1 hour to 5 hours.

3. The process according to any one of claims 1 to 2, wherein the feed rate in step (b) comprises 0.01 MT acid solution h -1 MT phytonutrients -1 Up to 0.25MT acid solution·h -1 MT phytonutrients -1 The first feed rate and the second duration are 0.3MT acid solution·h -1 MT phytonutrients -1 To 1MT acid solution·h -1 MT phytonutrients -1 The second feed rate. The method according to claim 1 , wherein the first duration is from 0.5 hours to 3 hours, and / or the second duration is from 0.5 hours to 2 hours.

5. The method according to claim 1, wherein the feed rate is 1MT acid solution·h -2 MT phytonutrients -1 To 3MT acid solution·h -2 MT phytonutrients -1 The rate of change increases from the first feed rate to the second feed rate.

6. The method of any one of claims 1 to 2, wherein step (b) further comprises adding a second phytonutrient, wherein the second phytonutrient is the same as the phytonutrient, the same as the dry acidic granules, or different from the phytonutrient and the dry acidic granules, or a combination thereof.

7. The method of claim 6, wherein the weight ratio of the phytonutrient to the second phytonutrient is 1:1 to 5:

1.

8. The method according to any one of claims 1 to 2, wherein the plant nutrients comprise nitrogen:phosphorus:potassium in a weight ratio of 5 to 20:3 to 40:0 to 30.

9. The method according to any one of claims 1 to 2, wherein the plant nutrient and / or the second plant nutrient consists of one or more nitrogen sources, one or more phosphorus sources, optionally one or more potassium sources, optionally water and optionally a binder.

10. The method according to any one of claims 1 to 2, wherein the inorganic acid is sulfuric acid, hydrochloric acid, nitric acid or phosphoric acid, or any combination thereof.

11. The method according to any one of claims 1 to 2, wherein the inorganic acid is sulfuric acid.

12. The method according to any one of claims 1 to 2, wherein the acid solution comprises 95% to 98% by weight of sulfuric acid.

13. The method of any one of claims 1 to 2, wherein the acidified particles are dried at a temperature of 55°C to 95°C.

14. The method of any one of claims 1 to 2, wherein the acidified particles are dried at a temperature of 60 to 80°C.

15. The method according to any one of claims 1 to 2, wherein the dried acidic particles have a moisture content of 0.05 wt% to less than 1 wt% and / or an average particle size distribution of 1 mm to 4 mm.

16. The method of any one of claims 1 to 2, wherein the dried acidic particles have a moisture content of 0.05 wt% to 0.8 wt%.

17. The method according to any one of claims 1 to 2, wherein the method further comprises: (d) passing the dried acidic granules through a sizing screen to obtain dried acidic granules of a desired particle size.

18. The process according to any one of claims 1 to 2, wherein the feed rate in step (b) comprises 0.01 MT acid solution·h -1 MT phytonutrients -1 To 0.20MT acid solution·h -1 MT phytonutrients -1 The first feed rate and the second duration are 0.25MT acid solution·h -1 MT phytonutrients -1 To 1MT acid solution·h -1 MT phytonutrients -1 The second feed rate.

19. A plant fertilizer comprising solid acidic fertilizer granules obtained by the method of any one of claims 1 to 18.

20. The plant fertilizer according to claim 19, wherein the plant fertilizer comprises from more than 10% to 40% by weight of inorganic acid and / or wherein the plant fertilizer comprises nitrogen:phosphorus:potassium:sulfur in a weight ratio of 5 to 20:3 to 40:0 to 30:3 to 25.

21. The plant fertilizer according to claim 19, wherein the plant fertilizer comprises more than 10% to 36% by weight of the inorganic acid.

22. The plant fertilizer according to claim 19, wherein the plant fertilizer comprises more than 10% to 35% by weight of the inorganic acid.

23. The plant fertilizer according to claim 19, wherein the solid acidic fertilizer granules have an average crushing strength of 2 kg / granule to 10 kg / granule, or 3 kg / granule to 7 kg / granule, or 4 kg / granule to 6 kg / granule.

24. The plant fertilizer of claim 19, wherein the solid acidic fertilizer granules are capable of forming a solution having a pH less than 4 when 10 grams of the plant fertilizer is dissolved in 100 ml of water at ambient conditions, wherein the pH of the water is 7 or greater before the plant fertilizer is dissolved in the water.

25. The plant fertilizer of claim 19, wherein the solid acidic fertilizer granules are capable of forming a solution having a pH less than 3 when 10 grams of the plant fertilizer is dissolved in 100 ml of water under ambient conditions, wherein the pH of the water is 7 or greater before the plant fertilizer is dissolved in the water.

26. The plant fertilizer according to claim 19, wherein the plant fertilizer is contained in a fertilizer blend or compound fertilizer comprising the plant fertilizer and other fertilizers.

27. A fertilization method, comprising applying the plant fertilizer prepared by the method according to any one of claims 1 to 18 or the plant fertilizer according to any one of claims 19 to 26 to at least a part of soil, crops, or soil and crops.

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