JP7107253B2 - Granular fertilizer and method for producing granular fertilizer - Google Patents

Description

The present invention relates to a granular fertilizer composed of a nitrogen fertilizer component such as ammonium sulfate and a magnesium fertilizer component such as magnesium sulfate as main raw materials, and a method for producing the same.

Granular fertilizers containing nitrogen fertilizer components and magnesium fertilizer components are known as fertilizers that are applied to strengthen the growth of leaves of crops. Typical nitrogen fertilizer components are ammonium sulfate, and magnesium fertilizer components are magnesium sulfate. . Since it contains nitrogen fertilizer component and magnesium fertilizer component, it is useful in soil and tea cultivation that lack them. Granular fertilizers are known in various shapes, such as spherical and pellet shapes, depending on the method of application. In particular, when applying fertilizer to large farmlands, mechanical application using a broadcaster is the mainstream. For this reason, a spherical fertilizer is desired because it has a long flight distance and is easy to apply evenly.

On the other hand, in general, a fertilizer composition containing a nitrogen fertilizer component and a magnesium fertilizer component is difficult to granulate, and the grain hardness after granulation is low and it is easy to powder during storage, so water or steam is used. It has been studied to produce granular fertilizer by binding fertilizer components together (Patent Documents 1 to 4). For example, Patent Literature 1 proposes a method for producing granular fertilizer in which a mixture of nitrogen fertilizer, magnesium sulfate and a sufficient amount of water is prepared and the mixture is press-molded. Further, Patent Document 2 proposes a granule produced by mixing a water-soluble inorganic salt such as ammonium sulfate or magnesium sulfate with water and extruding the resulting mixture. Further, in Patent Document 3, a slurry containing one or more crystalline substances in a supersaturated state is added to a fertilizer containing at least one of nitrogen, phosphoric acid, and potash as a main component. A wet granule manufacturing method has been proposed in which granulation is performed by Furthermore, in Patent Document 4, at least two selected from a nitrogen fertilizer component, a phosphorus fertilizer component, and a potassium fertilizer component and magnesium fertilizer are blended under high temperature conditions, and a part of the blend is dissolved by high temperature steam and granulated. A method for manufacturing compound fertilizer granules granulated in a machine has been proposed.

JP-A-5-97560 JP-A-11-181485 JP-A-61-40890 Japanese translation of PCT publication No. 2002-519290

Granular fertilizers suitable for mechanical spraying are required to have high crushing strength and resistance to pulverization so that they do not generate dust or clog the flow paths in the machine during spraying. No caking is required. In addition, it is also required to have a high density so that there is little variation in the flight distance when sprayed, and that it settles immediately after landing on the water in paddy fields and the like and lands on the soil. Furthermore, in order to make the elution rate of the fertilizer components into the soil uniform, it is required that the grain size of the fertilizer components contained in the granular fertilizer be uniform.

However, since the granular fertilizers described in Patent Documents 1 to 4 are granulated while dissolving the fertilizer components using a large amount of water or steam, the particle size of the fertilizer components contained in the granular fertilizers is uneven. was there. In addition, if an attempt is made to increase the grain hardness or decrease the moisture content to prevent caking, a drying process is required, which deteriorates economic efficiency and does not necessarily provide sufficient performance.

As described above, the known technology is advantageous for mechanical spreading and is not sufficient for a granular fertilizer having a uniform elution rate of fertilizer components.

The inventors of the present invention have made intensive studies to solve the above problems, and found that particles (particles A) substantially composed of a nitrogen fertilizer component and particles (particles B) substantially composed of a magnesium fertilizer component are integrated. A granular fertilizer in which secondary particles are formed by a process, wherein particles A have a particle size of more than 0.1 mm and particles of 2 mm or less account for 50% by weight or more of particles A, and particles B have a particle size of 0.1 mm. 50% by weight or more of the particles B, and the fertilizer contains 50-80% by weight of the nitrogen fertilizer component and 50-20% by weight of the magnesium fertilizer component. As a result, it was found that a granular fertilizer having a high grain hardness after secondary particle formation, a high fertilizer yield after production, and a uniform elution rate of fertilizer components can be obtained.

In addition, the inventors have created an invention of a granular fertilizer which is improved in various ways such that powdering does not easily occur even during storage of the fertilizer and caking does not occur.

In addition, in the method for producing a granular fertilizer of the present invention, particles (particles A) substantially made of a nitrogen fertilizer component and particles (particles B) substantially made of a magnesium fertilizer component are integrated to form secondary particles. A method for producing a granular fertilizer, wherein the particles A have a particle size of more than 0.25 mm and 2 mm or less account for 70% by weight or more of the particles A, and the particles B have a particle size of 0.25 mm more than 50% by weight of the particles B and 2 mm or less, and 50 to 80% by weight of the particles A and 20 to 50% by weight of the particles B with respect to the total weight of the granular fertilizer. A method for producing a granular fertilizer comprising a step of mixing in the presence of moisture to obtain a mixture and a step of molding the mixture to form secondary particles, and various improved methods thereof. Created by the inventors.

According to the present invention, the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is uniform, the grain hardness after secondary particle formation is high, the fertilizer yield after production is high, and powdering preferably occurs during fertilizer storage. It is possible to obtain a granular fertilizer that is hard to caking and hard to cause caking.

<Nitrogen Fertilizer Ingredients>
The nitrogenous fertilizer component used in the present invention is not particularly limited, and any known component that acts as a nutrient for plant nitrogen can be used. Specific examples of nitrogen fertilizer components include ammonium sulfate, ammonium chloride, ammonium nitrate, ammonium phosphate, and urea. Among these, ammonium sulfate is particularly preferable because it is excellent in dissolution and grain hardness when made into a granular fertilizer. Ammonium sulfate is, for example, an aqueous solution of ammonium sulfate obtained by contacting coke oven waste gas with sulfuric acid, or in the production of caprolactam, an aqueous solution of caprolactam and ammonium sulfate is obtained by adding ammonia to caprolactam sulfate to obtain a mixed solution of caprolactam and ammonium sulfate. Ammonium sulfate is crystallized from an aqueous solution of ammonium sulfate obtained by separating the aqueous solution, and can be used as fine crystalline ammonium sulfate. Separation of crystals and mother liquor can be carried out by a known method. For example, it is obtained by drying after separating from the liquid by centrifugation. If the degree of supersaturation is too high during crystallization, the crystals of the fine-grain ammonium sulfate agglomerate abruptly and take in the mother liquor, resulting in a large particle size, a high water content, and a large amount of impurities. By precipitating, it is possible to obtain fine-grained crystalline ammonium sulfate having crystal orientation and high crystallinity. The degree of crystallinity can be measured by performing two-dimensional X-ray diffraction, and the degree of orientation obtained from the measurement results is preferably 0.995 or more. More preferably, the degree of orientation is 0.997 or more, and the degree of orientation of 1.0 is the highest crystallinity, and is most preferred. The proportion of fine-grain ammonium sulfate containing ammonium sulfate is preferably 95% by weight or more, and when it is 98% by weight or more, fine-grain crystalline ammonium sulfate has high crystallinity, which is most preferable. The degree of orientation is an index that indicates the degree of alignment of crystals. ).

Degree of orientation=(180-orientation peak half width)/180 (1).

The fine crystalline ammonium sulfate thus obtained can be used as it is for the particles A which are one of the constituent elements of the granular fertilizer of the present invention. In this case, the content of components other than ammonium sulfate derived from the mother liquor of the aqueous ammonium sulfate solution is preferably less than 0.3% by weight, more preferably less than 0.2% by weight, in the fine-grain ammonium sulfate.

In addition, the particle size of the fine crystal ammonium sulfate is preferably 1.7 mm or less because the smaller the particle size, in which the crystals are aggregated and the mother liquid is not taken in, the better the caking property is. It is more preferably 1.4 mm or less, still more preferably 1.18 mm or less. The particle size of fine crystal ammonium sulfate can be obtained by classifying with a sieve (10 mesh = 1.7 mm, 12 mesh = 1.4 mm, 14 mesh = 1.18 mm).

The content of ammoniacal nitrogen in the fine crystal ammonium sulfate is preferably 20.5% or more, more preferably 21.0% or more, from the viewpoint of the fertilizer effect as a nitrogen source per unit weight. The content of ammoniacal nitrogen in the fine-grained ammonium sulfate is a value measured by the formaldehyde method according to the official fertilizer analysis method.

The moisture content of the nitrogen fertilizer component is preferably 5% by weight or less. It is more preferably 4% by weight or less, still more preferably 3% by weight or less. When the nitrogen fertilizer component is fine crystalline ammonium sulfate, the moisture content is preferably 0.3% by weight or less. The content is more preferably 0.2% by weight or less, still more preferably 0.1% by weight or less, and most preferably 0% when water is completely dried. In addition, the moisture content of the nitrogen fertilizer component is a value measured by the heating weight loss method according to the official fertilizer analysis method.

<Particle A>
As will be described later, the granular fertilizer of the present invention includes particles (such particles are sometimes referred to as "particles A") consisting essentially of a nitrogen fertilizer component and particles consisting essentially of a magnesium fertilizer component (such particles are referred to as "particles B ) are integrated to form secondary particles.

Particles A are particles consisting essentially of nitrogenous fertilizer components. Here, "substantially" means that the nitrogen fertilizer component content in the particles A is 90% by weight or more on average with respect to the weight of the particles A. The proportion of the particles A containing the nitrogen fertilizer component is preferably 95% by weight or more, more preferably 98% by weight or more, and most preferably 100% by weight. The particles A can be obtained by crystallizing by crystallization.

In the particles A used for producing the granular fertilizer of the present invention, particles having a particle size of more than 0.25 mm and 2 mm or less preferably account for 70% by weight or more of the entire particles A. More preferably, particles with a particle size of more than 0.25 mm and 1.7 mm or less account for 70% by weight or more of the total particles A, and more preferably particles with a particle size of more than 0.25 mm and 1.4 mm or less. It is 70% by weight or more of the whole A. If the particle size exceeds 2 mm, the contact area between the particles is small, making it difficult to granulate. occur. When particles having a particle size of 0.25 mm or less are contained in a large amount, the bulk density of the particles A is lowered and granulation is difficult, resulting in a decrease in raw material utilization efficiency. The particle size and amount of the particles A here are determined by sieving (for example, 9 mesh = 2.0 mm, 10 mesh = 1.7 mm, 12 mesh = 1.4 mm, 60 mesh = 0.25 mm). can be obtained by classifying

The bulk density of the particles A used for producing the granular fertilizer of the present invention is preferably 0.90 g/ml or more and 1.1 g/ml or less. In order to prevent scattering during transportation and increase the granulation yield during granulation, the bulk density is more preferably 0.93 g/ml or more and 1.1 g/ml or less, more preferably 0.96 g/ml. It is more preferable that it is more than or equal to 1.1 g/ml or less. The bulk density of the particles A is measured according to "JIS R 1628:1997 Method for measuring bulk density of fine ceramic powder".

<Magnesium Fertilizer Ingredients>
The magnesium fertilizer component used in the present invention is not particularly limited, and any known component, including known components, that acts as a nutrient for the magnesium content of plants can be used. Specific examples of magnesium fertilizer components include magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium hydroxide, magnesium carbonate, and the like. Among these, magnesium sulfate is particularly preferable because it is excellent in dissolution and grain hardness when made into a granular fertilizer. Examples of preferred magnesium sulfate are preferably at least one selected from the group consisting of magnesium sulfate anhydride, magnesium sulfate monohydrate, magnesium sulfate trihydrate, and magnesium sulfate heptahydrate, and At least one selected from the group consisting of magnesium sulfate anhydride, magnesium sulfate monohydrate and magnesium sulfate trihydrate is preferably used because it is advantageous in that it is difficult to pulverize. It is more preferable to use magnesium sulfate monohydrate (for example, Kieserite (Sumitomo Corporation)). Magnesium sulfate is obtained, for example, by pulverizing raw ore mined from a mine and separating it from potassium chloride and the like by electrolysis, or by neutralizing and decomposing light-burnt magnesium with sulfuric acid as a raw material. The magnesium content in terms of MgO is preferably 15% or more, more preferably 20% or more, and even more preferably 25% or more, from the viewpoint of the fertilizer effect as a magnesium source per unit weight. The magnesium content of magnesium sulfate in terms of MgO is a value measured by atomic absorption spectrophotometry according to the official fertilizer analysis method. Magnesium fertilizer components are usually obtained as granular components, and the particle size thereof is preferably 2 mm or less. It is more preferably 1.7 mm or less, and still more preferably 1.4 mm or less. The particle size and amount of the magnesium fertilizer component can be obtained by classifying with a sieve (10 mesh = 1.7 mm, 12 mesh = 1.4 mm, 14 mesh = 1.18 mm). The moisture content of the magnesium fertilizer component is preferably 5% by weight or less. It is more preferably 4% by weight or less, still more preferably 3% by weight or less. When the magnesium fertilizer component is magnesium sulfate, the moisture content is preferably 0.3% by weight or less. It is more preferably 0.2% by weight or less, and still more preferably 0.1% by weight or less. In addition, the moisture content of the magnesium fertilizer component is a value measured by the heating weight loss method according to the official fertilizer analysis method.

<Particle B>
Particles B are particles consisting essentially of the magnesium fertilizer component. Here, "substantially" means that the content of the magnesium fertilizer component in the particles B is 90% by weight or more on the average with respect to the weight of the particles B. The proportion of the particles B containing the magnesium fertilizer component is preferably 95% by weight or more, more preferably 98% by weight or more, and most preferably 100% by weight. The particles B can be obtained by pulverizing raw ore mined from a mine and separating it from potassium chloride and the like by electrolysis.

Particles B used in the production of the granular fertilizer of the present invention preferably have a particle size of more than 0.25 mm and 2 mm or less in an amount of 50% by weight or more of the entire particles B. More preferably, particles with a particle size of more than 0.25 mm and 1.7 mm or less account for 50% by weight or more of the total particles B, and more preferably particles with a particle size of more than 0.25 mm and 1.4 mm or less. The content of B is 50% by weight or more of the total. When particles having a particle size of more than 2 mm are contained in a large amount, the contact area between the particles is small during granulation, making it difficult to granulate, resulting in a decrease in grain hardness. When particles B having a particle size of 0.25 mm or less are contained in a large amount, the bulk density of the particles B is lowered, making it difficult to granulate, and the utilization efficiency of the raw material is lowered. The particle size and amount of the particles B here are determined by sieving (for example, 9 mesh = 2.0 mm, 10 mesh = 1.7 mm, 12 mesh = 1.4 mm, 60 mesh = 0.25 mm). can be obtained by classifying

The bulk density of the particles B used for producing the granular fertilizer of the present invention is 0.95 g/ml or more and 1.10 g/ml or less. In order to prevent scattering during transportation and increase the granulation yield during granulation, the bulk density is more preferably 0.97 g/ml or more and 1.10 g/ml or less, more preferably 0.99 g/ml. More preferably, it is 1.10 g/ml or less. The bulk density of the particles B is measured according to "JIS R 1628:1997 Method for measuring bulk density of fine ceramic powder".

<Granular Fertilizer>
The granular fertilizer of the present invention is a granular fertilizer in which particles (particles A) substantially composed of a nitrogen fertilizer component and particles (particles B) substantially composed of a magnesium fertilizer component are integrated to form secondary particles. . That is, it is possible to observe a portion of particles A and a portion of particles B in the granular fertilizer using a microscope. In order to obtain such a granular fertilizer, the particles A and B as raw materials are mixed in the presence of water, and the mixture is molded (also called granulation).

Particles A and B are mixed in a mixer in the presence of moisture, and granulation, pulverization, sizing, and classification are sequentially performed to obtain a granular fertilizer having hardness, bulk density, and shape suitable as a fertilizer. can be done.

Components other than the particles A and B may be used as long as they do not deviate from the gist of the present invention or impair the purpose. For example, there are other nutrients that have a fertilizing effect, substances that improve shape retention such as binders, and additives such as inorganic fillers and organic fillers.

The method for mixing the particles A and the particles B is not particularly limited to the type of mixer as long as it can be uniformly mixed. Although a fixed container type mixer such as a paddle type can be used, a paddle type mixer is preferably used because continuous processing is possible. The mixing time is preferably 2 minutes or more and 15 minutes or less, more preferably 5 minutes or more and 10 minutes or less. If the mixing time is shorter than 2 minutes, the particles A and B will not be uniformly dispersed in the mixture, and the particles will be uneven when granulated. If the mixing time exceeds 15 minutes, it is economically disadvantageous because the capacity of the mixer is increased in the continuous production of fertilizer.

The amount of water present when the particles A and B are mixed is preferably 0.1 to 1.9 parts by weight when the total weight of the particles A and B is 100 parts by weight. More preferably 0.3 to 1.7 parts by weight, still more preferably 0.5 to 1.5 parts by weight. If the amount of water present is less than 0.3 parts by weight, the binding force between the particles A and B is insufficient during granulation, leading to a decrease in granulation yield, and the hardness during storage is insufficient, resulting in powdery granular fertilizer. easier to convert. If the amount of water present exceeds 1.7 parts by weight, the amount of adherence to the equipment increases when the mixture is discharged from the mixer and conveyed to the granulator, resulting in a decrease in yield or granular fertilizer. The caking property deteriorates during storage.

As a molding method, a known method can be used, but compression granulation is preferable, and the compression granulation apparatus may be any of a tablet method, a plate-like method, and a briquette method, but the tablet method has low production efficiency. The briquette method is preferable because it is difficult to mass-produce granular fertilizer due to its low density, and it is difficult to produce spherical granular fertilizer with less burrs using the plate method. As a briquette-type compression granulator, for example, Briquette (registered trademark) BSS type (manufactured by Shinto Kogyo Co., Ltd.) can be preferably used.

There is no particular limitation on the method of supplying a mixture (also referred to as a granulation raw material) in which particles A and B are mixed in the presence of moisture to a compression granulator. It can be directly supplied to the granulator from an attached conveyer, or supplied from the hopper conveyer to the granulator via a belt conveyor, a bucket conveyor, or the like.

The granulation pressure indicates a value (linear pressure) obtained by dividing the total load applied to the granulated raw material by the effective width, and the effective width indicates the major diameter on the compressor side of the portion where the load is applied to the granulated raw material. For example, in the tablet method, the effective width is the major diameter of the tablet portion, and in the briquette method using rollers, the effective width is the length of the portion where the granulated raw material is compressed by the rollers. Granulation pressure is preferably in the range of 6.0 kN/cm or more and 30.0 kN/cm or less. It is more preferably 7.0 kN/cm or more and 30.0 kN/cm or less, and still more preferably 8.0 kN/cm or more and 30.0 kN/cm or less. If the granulation pressure is less than 6.0 kN/cm, granulation itself of the granulation raw material does not occur due to insufficient pressure. If the granulation pressure exceeds 30.0 kN/cm, cracks may occur in the granules obtained due to the excessive pressure, or an excessive load is applied to the compression granulator, resulting in a significant reduction in the life of the device. .

The rotation speed of the granulation roller is the rotation speed of the roller in the briquette method and the plate-like method in which compression granulation is performed using a roller, and is preferably 40 rpm or more. It is more preferably 50 rpm or more, and still more preferably 60 rpm or more. If the rotation speed of the granulation roller is less than 40 rpm, the granulation pressure on the raw material increases, causing cracks in the granules and reducing the production amount.

The burr thickness of the compression granulator indicates the shortest diameter of the granulated raw material at the portion where the load is applied to the granulated raw material. For example, in the tablet method, the burr thickness is the short diameter of the tablet portion, and in the briquette method using a roller, the burr thickness is the length of the plate-like portion of the granulated product obtained by granulation. be. The burr thickness is preferably in the range of 1.0 mm or more and 2.5 mm or less, and more preferably in the range of 1.2 mm or more and 2.0 mm or less. When the burr thickness is less than 1.2 mm, both the crushing strength and the yield of the granular fertilizer tend to decrease. If the burr thickness exceeds 2.0 mm, the shape of the granular fertilizer becomes unsuitable for fertilizer application, and the granulated granular fertilizer is crushed, for example, by a vibration sieve using a crushing ball to make the particle size uniform. In that case, it is not preferable because it causes clogging of the sieve.

In order to obtain a granular fertilizer with less burrs, high crushing strength, less dust generation, and less caking, the raw material is granulated using a compression granulator, and after compression granulation using a crusher, Preferably, the granules are pulverized, the granules are sized using a spheroidizer, and the sized granular fertilizer is classified using a classifier. There are no restrictions on the method of transporting the granular fertilizer in each process, but it is possible to use gravity, conveyer, or air blowing. A method of transporting to a crusher/spheroidizer/classifier is preferred. It is preferable to use a material having corrosion resistance to granular fertilizers, such as SUS316L or resin, for the powder-contacting parts of equipment including these transportation equipment.

A granular fertilizer granulated by a compression granulator can be crushed, sized and classified to obtain a granular fertilizer having hardness, bulk density and shape suitable for fertilizer.

In order to obtain a granular fertilizer with a uniform particle size, it is preferable to crush the compressed granulated granular fertilizer using a crusher. The type of crusher is not particularly limited, and for example, various crushers such as jaw crushers and roll crushers, various mills such as roller mills and cutting mills, and vibrating sieves containing crushing media are preferably used. It is also possible to use these crushers in combination.

In order to obtain a granular fertilizer with a spherical shape and less burrs, it is preferable to use a granule regulating machine. There are no particular restrictions on the type of grain sizer, and for example, a high-speed rolling method, an oscillator type, a crushing method, a centrifugal rotation method, etc. are preferably used. Dalton) is more preferable for sizing the granular fertilizer.

The treatment time of the grain sizer is preferably in the range of 0.2 to 5.0 minutes, more preferably in the range of 0.3 to 3.0 minutes. If the processing time of the granule sizing machine becomes shorter than the above, burr removal from the granular fertilizer becomes insufficient. If the processing time of the granule regulating machine is longer than the above, the amount of parts other than burrs that are cut increases, and the yield of granular fertilizer decreases. Furthermore, since the time required for sizing treatment increases, the yield of granular fertilizer per unit time also decreases.

The rotation speed of the grain size regulator is preferably in the range of 50 to 2000 rpm, more preferably in the range of 100 to 1500 rpm. If the rotational speed of the granule regulating machine is lower than the above range, burr removal from the granular fertilizer becomes insufficient, and more time is required for the granulation treatment, resulting in a decrease in the yield of granular fertilizer per unit time. If the rotation speed of the grain sizer exceeds the above range, problems such as an increase in noise and a reduction in equipment life will occur.

In order to obtain granular fertilizer having a predetermined particle size or larger, it is desirable to classify the granular fertilizer using a classifier. The type of classifier is not particularly limited as long as dry classification is possible, but it is preferable to use a vibrating sieve. The mesh size of the sieve is not particularly limited as long as it is a size that allows a predetermined particle size to be obtained. A classification method in which sieves having mesh openings are combined to obtain granular fertilizer having a particle size of 2.0 to 4.0 mm is preferred.

In the granular fertilizer of the present invention, particles A have a particle size of more than 0.1 mm, particles of 2 mm or less account for 50% by weight or more of the particles A, and particles B have a particle size of more than 0.1 mm. Particles of 2 mm or less account for 50% by weight or more of the particles B, and the granular fertilizer contains 50 to 80% by weight of the nitrogen fertilizer component and 50 to 20% by weight of the magnesium fertilizer component.

The amount of the nitrogen fertilizer component and the magnesium fertilizer component contained in the granular fertilizer is more preferably 55 to 78% by weight of the nitrogen fertilizer component and 45 to 22% by weight of the magnesium fertilizer component. more preferably 60-75% by weight and 40-25% by weight of the magnesium fertilizer component. When the nitrogen fertilizer component is less than 50% by weight and the magnesium fertilizer component is more than 50% by weight, the proportion of the magnesium fertilizer component is high and the grain hardness is lowered, making it easy to powder. When the nitrogen fertilizer component is more than 80% by weight and the magnesium fertilizer component is less than 20% by weight, the ratio of the nitrogen fertilizer component and the magnesium fertilizer component in the granular fertilizer is uneven, which hinders the growth of crops. The amounts of the nitrogen fertilizer component and the magnesium fertilizer component contained in the granular fertilizer can be adjusted to a desired range by adjusting the blending amounts of the particles A and B.

In the granular fertilizer of the present invention, the particle size of the particles A is more than 0.1 mm and 2.0 mm or less, and 50% by weight or more of the particles A, more preferably more than 0.1 mm and 1.0 mm or less. is 50% by weight or more in the particles A. When many of the particles A have a particle size of more than 2 mm, the grain hardness is lowered because the ratio of the raw material in the granular fertilizer is small. When many of the particles A have a particle size of 0.1 mm or less, they become pulverized during storage, and the cohesion of the granular fertilizer deteriorates. The particle size of the particles A can be obtained by analyzing the cross section of the granular fertilizer by scanning electron microscopic observation-energy dispersive X-ray analysis to identify particles containing nitrogen fertilizer components.

In the granular fertilizer of the present invention, the particle size of the particles B is more than 0.1 mm and 2 mm or less, and 50% by weight or more of the particles B, preferably more than 0.1 mm and 1.0 mm or less. 50% by weight or more. When many of the particles B have a particle size of more than 2 mm, the grain hardness is lowered because the ratio of the raw material in the granular fertilizer is small. If many of the particles B have a particle size of 0.1 mm or less, they are pulverized during storage, and the cohesiveness of the granular fertilizer deteriorates. The particle size of the particles B can be obtained by analyzing the cross section of the granular fertilizer by scanning electron microscopic observation-energy dispersive X-ray analysis to identify particles containing magnesium fertilizer components.

As a method for adjusting the particle size range and amount of the particles A and B, a desired range can be obtained by sieving the particles A or B before molding. Therefore, in obtaining the granular fertilizer of the present invention, particles A having a particle size of more than 0.25 mm and 2 mm or less account for 70% by weight or more of the particles A, and particles A having a particle size of more than 0.25 mm and 2 mm or less. It is preferable to mold a mixture of particles B in which the particles of B account for 50% by weight or more of the particles B.

The grain hardness of the granular fertilizer after the formation of secondary particles may vary slightly over time from the formation of the secondary particles, but the granular fertilizer of the present invention when distributed as a product assuming the time of use and transportation. Grain hardness is preferably 2 kgf or more. If the grain hardness is less than 2 kgf, powdering is likely to occur during storage or transportation of the granular fertilizer, which causes solidification of the granular materials through the powder. In addition, the granules collapse during spraying, making uniform fertilization difficult. On the other hand, the upper limit is not particularly limited, but it is preferably 5 kgf or less. If it exceeds 5 kgf, the granular fertilizer may have poor solubility in soil, resulting in reduced fertilizer efficacy. It is more preferably 3 kgf or more and 5 kgf or less, and still more preferably 3.5 kgf or more and 4.5 kgf or less. The grain hardness of the granular fertilizer is obtained by measuring the grain hardness of 20 grains of the granular fertilizer with a Kiya type hardness meter, and taking the average value of these grain hardnesses as the grain hardness.

It is desirable that the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component from the granular fertilizer should be the same decay rate for the purpose of imparting the fertilizer effect to the crops as designed. The ratio of dissolution rates normalized by volume is preferably 0.8 to 1.2. It is more preferably 0.9 to 1.1, and most preferably 1.0, which indicates that the attenuation ratios match. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component from the granular fertilizer was determined by putting 5 g of granular fertilizer into a 100 ml capped glass tube, adding 100 ml of water, immersing the tube, sealing the tube, and keeping the temperature at 25°C. Allow to stand in a constant temperature bath, remove the glass tube after 5 hours, filter the solution with chemical filter paper, quantitatively analyze the fertilizer components eluted in water, measure the initial amount, and measure the following formula (3), It is obtained from equations (4) and (5).

Elution ratio of nitrogen fertilizer component =
(Amount of N dissolved in water)/(Amount of N contained in 5 g of granular fertilizer) (3).

Elution ratio of magnesium fertilizer component =
(Amount of magnesium dissolved in water in terms of MgO)/(Amount of magnesium in 5 g of granular fertilizer in terms of MgO) (4).

Elution rate ratio of nitrogen fertilizer component and magnesium fertilizer component =
Elution ratio of nitrogen fertilizer component/Elution ratio of magnesium fertilizer component (5).

The raw material is granulated using a compression granulator, the granules after compression granulation are crushed using a crusher, the granules are sized using a spherical granulator, and a classifier is used. The fine powder under sieves obtained when the granular fertilizer after sieving is classified using the sieving method can be recycled and mixed into the raw material and used as the raw material. The yield of the granular fertilizer is preferably 60% or more in order to reduce the waste amount of the granular fertilizer during granulation and sizing as much as possible, or to recycle it to the granulation process without discarding it. It is more preferably 65% or more, still more preferably 70% or more, and most preferably 100% when completely recovered. The yield is the weight ratio of the granular fertilizer obtained by granulation and sizing with respect to the weight of the granulated raw material put into the granulator, and is represented by the following formula (6).

Yield = (Weight of granular fertilizer) / (Weight of granulated raw material to be fed into granulator)
×100 (%) (6).

The shape of the granular fertilizer is such that the ratio of the diameter of the major axis to the diameter of the minor axis (diameter of the major axis/diameter of the minor axis) of the granular fertilizer is 1.0 so that when fertilizer is applied mechanically, it does not adhere to the leaves of crops and falls into the soil. It is preferably 0 or more and 1.4 or less, more preferably 1.0 or more and 1.3 or less, and even more preferably 1.0 or more and 1.2 or less. If the leaf fertilizer is not spherical, for example flat, it may stick to the leaves and not fall off, resulting in leaf scorch and insufficient supply of nutrients to the soil.

In mechanical fertilization, the grain size of the granular fertilizer is preferably 2 mm or more and 4 mm or less, and accounts for 90% by weight or more of the total fertilizer in order to spread the fertilizer uniformly. More preferably, those having a thickness of 2.5 mm or more and 3.5 mm or less account for 90% by weight or more. A granular fertilizer having a predetermined particle size can be obtained by classification using a classifier, and dry classification can be preferably employed. Although the type of dry classifier is not particularly limited, it is preferable to use a vibrating sieve. The mesh size of the sieve is not particularly limited as long as it is a size that allows a predetermined particle size to be obtained. A classification method in which sieves having mesh openings are combined to obtain granular fertilizer having a particle size of 2.0 to 4.0 mm is preferred. It can be obtained by classifying with a sieve (5 meshes = 4.0 mm, 6 meshes = 3.5 mm, 8 meshes = 2.5 mm, 9 meshes = 2.0 mm).

The granular fertilizer preferably has a bulk density of 0.90 g/ml or more and 1.1 g/ml or less so that it can be uniformly applied in mechanical fertilization and settles on the soil immediately after it reaches water in a paddy field or the like. It is more preferably 92 g/ml or more and 0.98 g/ml or less, and further preferably 0.94 g/ml or more and 0.96 g/ml or less. The bulk density of granular fertilizer is measured according to "JIS R 1628:1997 Method for measuring bulk density of fine ceramics powder".

The moisture content of the granular fertilizer is preferably 2.0% by weight or less from the viewpoint of preventing solidification of the granular fertilizer during long-term storage. It is more preferably 1.8% by weight or less, still more preferably 1.5% by weight or less. Also, the lower limit is preferably 0.3% by weight or more. If the moisture content of the granular fertilizer exceeds 2.0% by weight, during storage of the granular fertilizer, the fertilizer components are eluted and solidified at the contact points between the granular fertilizers, causing the grains to cross-link and agglomerate, resulting in poor handling. I have something to do. If the moisture content is less than 0.3% by weight, the bonding strength between the nitrogen fertilizer component and the magnesium fertilizer component contained in the granular fertilizer may decrease, leading to a decrease in the hardness of the granular fertilizer. The moisture content of the granular fertilizer is the value measured by the heating weight loss method according to the official method for analysis of fertilizers.

Caking is a phenomenon in which granules are bridging at their contact points to form clumps. Failure to spray will adversely affect the growth of crops. The solidification rate of the granular fertilizer is preferably 20% or less for easy handling. When the solidification rate exceeds 20%, the fluidity from the hopper is lowered, and mechanical fertilization may become difficult. It is more preferably 15% or less, still more preferably 10% or less, and most preferably 0% where there is no caking. The solidification rate was determined by placing 750 g of granular fertilizer filled in a small plastic bag on the top and bottom of each dummy fertilizer bag (750 g per bag), placing a wooden board on top of it, and accumulating with a weight of 60 kg. It is the ratio (%) of the solidified portion weight (g) in the granular fertilizer after loading for one month, and is shown by the following formula (7).

Solidification rate (%)=(weight of solidified portion after loading for one month)/750×100 (7).

The compaction strength of the granular fertilizer is preferably 1 kg/cm ² or less. If it is 1 kg/cm ² or more, for example, since the solidified portion is difficult to flow out of the flexible container, it is not easy to put it into a hopper, or in mechanical fertilization, the granular fertilizer cannot be uniformly spread to the growing plants. Inferior. More preferably, the consolidation strength is 0.5 kg/cm ² or less, and still more preferably 0.2 kg/cm ² or less. Most preferably and ideally, it is 0 kg/cm ² . The caking strength is a value measured by pressing the needle vertically into the upper surface of the fertilizer using a Yamanaka soil hardness tester.

The pulverization rate of the granular fertilizer is preferably 1.0% or less to prevent caking during storage. If the pulverization rate exceeds 1.0%, the pulverized powder is likely to be caking during storage, and the granular fertilizer cannot be spread to the plants to be grown in mechanical fertilization, resulting in poor handleability. It is more preferably 0.5% or less, still more preferably 0.3% or less, and most preferably 0% where there is no dusting. The pulverization rate is the ratio (%) of particles having a particle size of 2 mm or less obtained by using a sieve with an opening of 2 mm among the granular fertilizers after loading for one month with a weight of 60 kg for 750 g of the granular fertilizer. , is represented by the following formula (8).

Pulverization rate (%)=(weight (g) of particles having a particle size of 2 mm or less)/750×100 (8).

After granulating, pulverizing, sizing, and classifying to produce a granular fertilizer, the granular fertilizer is added with talc, clay, kaolin, bentonite, polyethylene glycol, metal stearate, metal lauryl sulfate, as anti-caking agents. At least one selected from calcium carbonate, silicon oxide, calcium terephthalate, aluminum oxide, titanium oxide, calcium phosphate, and lithium fluoride can be coated on the surface of the granular fertilizer to obtain a granular fertilizer. As a method of coating, the granulated raw material is granulated and sized, and after classifying with a classifier, if it is uniformly coated, it may be added at the exit of the classifier, or mixed and coated using a mixer. Alternatively, the coating may be carried out by spraying on a belt conveyor.

The amount of the anti-caking material added to the granular fertilizer is preferably 0.05 to 3.0% by weight with respect to 100% by weight of the granular fertilizer. 0.1 to 0.3% by weight is more preferable with respect to 100% by weight of the granular fertilizer composition in order to obtain a fertilizer with no adverse effects and good solubility as a fertilizer. 0.15 to 0.25% by weight is more preferable with respect to 100% by weight of granular fertilizer in order to reduce adhesion loss to equipment.

When using the granular fertilizer of the present invention, it may be either a single fertilizer or a bulk blend fertilizer obtained by dry-blending other granular fertilizers. Since this mixed fertilizer can be blended at any ratio, blending corresponding to each crop can be performed.

The aspects of the present invention will be described more specifically below using examples, but the present invention should not be construed as being limited to the following examples.

The methods for measuring physical properties and the like are as follows. In addition, unless otherwise specified, 10 samples were measured, and the arithmetic average was obtained.

(1) Particle size before molding of particles A and B The particle sizes of particles A and B before molding are sieves with an opening of 9 mesh = 2.0 mm and an opening of 60 mesh = 0.25 mm. was used to calculate the ratio of particle diameters exceeding 0.25 mm to 2 mm or less according to the following formula.
Proportion (% by weight) of particles having a particle size of more than 0.25 mm and less than or equal to 2 mm=(weight of particles having a particle size of more than 0.25 mm and less than or equal to 2 mm)/(weight of particles before sieving)×100.

(2) Particle size of particle A and particle B after molding granular fertilizer Analyzed, particles containing nitrogen fertilizer components and particles containing magnesium fertilizer components were discriminated, and the particle size of 100 grains was measured at random.

(3) Moisture Content of Particle A and Particle B Before Molding The moisture content of Particle A and Particle B before molding was measured by weight measurement after heating Particle A or Particle B at 130° C. for 3 hours before heating. It is a value obtained from the initial heating loss, and was calculated by the following formula.
Moisture content of particles A (% by weight) = ((weight of particles A before heating) - (weight of particles A after heating))/(weight of particles A before heating) x 100
Moisture content of particles B (% by weight)=((weight of particles B before heating)−(weight of particles B after heating))/(weight of particles B before heating)×100.

(4) Grain hardness after secondary particle formation of granular fertilizer Grain hardness after secondary particle formation (after molding) of granular fertilizer is measured by measuring the grain hardness of 20 granules with a Kiya hardness meter. It is the average hardness.

(5) Yield of Granular Fertilizer The yield of granular fertilizer is the weight of granular fertilizer obtained by granulation and sizing with respect to the weight of granulated raw material put into the granulator, and was calculated by the following formula. .
Yield (%) of granular fertilizer = (weight of granular fertilizer)/(weight of granulated raw material) x 100.

(6) Particle size of granular fertilizer The particle size of granular fertilizer is calculated using sieves with openings of 9 mesh = 2.0 mm and 5 mesh = 4.0 mm, and the ratio of particles with a particle size of 2 mm or more and 4 mm or less according to the following formula. was calculated.
Ratio (% by weight) of granular fertilizers of 2 mm or more and 4 mm or less = (weight of particles with particle diameters of 2 mm or more and 4 mm or less)/(weight of granular fertilizer before sieving) x 100.

(7) Contents of Nitrogen Fertilizer Component and Magnesium Fertilizer Component after Forming Granular Fertilizer is analyzed by the official fertilizer analysis method, the N content is measured by the combustion method, and the magnesium content in terms of MgO is measured by the atomic absorption method. was calculated.
Content (% by weight) of the nitrogen fertilizer component after molding into granular fertilizer=(content of N in granular fertilizer)/(content of N in particle A before molding)×100.
Content (% by weight) of the magnesium fertilizer component after molding into granular fertilizer=(MgO content in granular fertilizer)/(MgO content before molding of particles B)×100.

(8) Elution rate ratio of nitrogen fertilizer component and magnesium fertilizer component from granular fertilizer (decay rate ratio)
The ratio of the elution rates of the nitrogen fertilizer component and the magnesium fertilizer component normalized by the initial amount from the granular fertilizer was obtained by putting 5 g of granular fertilizer into a 100 ml capped glass tube, adding 100 ml of water, soaking, and removing the plug. After 5 hours, remove the glass tube, filter the solution with chemical filter paper, quantitatively analyze the fertilizer components eluted into the water, and determine the nitrogen fertilizer component and magnesium fertilizer component. The eluted amount was calculated, and the initial amount was measured and calculated according to the following formula.
Elution ratio of nitrogen fertilizer component = (amount of N dissolved in water)/(amount of N contained in 5 g of granular fertilizer)
Elution ratio of magnesium fertilizer component = (amount of magnesium in terms of MgO eluted in water)/(amount of magnesium in terms of MgO contained in 5 g of granular fertilizer)
The ratio of the elution rates of the nitrogen fertilizer component and the magnesium fertilizer component = the elution rate of the nitrogen fertilizer component/the elution rate of the magnesium fertilizer component.

(9) Ratio of major axis diameter to minor axis diameter of granular fertilizer (major axis diameter/minor axis diameter)
The ratio of the major axis diameter to the minor axis diameter of the granular fertilizer is obtained by measuring the major axis diameter and the minor axis diameter with an image analysis type particle size measuring device using a photographed image of the granular fertilizer. Calculated by dividing by the diameter.

(10) Bulk Density of Granular Fertilizer The bulk density of granular fertilizer was measured according to "JIS R 1628: 1997 Method for measuring bulk density of fine ceramics powder".

(11) Moisture Percentage of Granular Fertilizer The moisture percentage of the granular fertilizer is a value obtained from weight loss on heating when the granular fertilizer before heating is heated at 130° C. for 3 hours and then weighed, and was calculated by the following formula.
Moisture content of granular fertilizer (% by weight)=((weight of granular fertilizer before heating)−(weight of granular fertilizer after heating))/(weight of granular fertilizer before heating)×100.

(12) Solidification rate of granular fertilizer The solidification rate of granular fertilizer was measured by placing 750 g of granular fertilizer in a small plastic bag, placing dummy fertilizer bags at the top and bottom, and placing a wooden board on top of each bag. , is the ratio of the solidified portion weight (g) in the granular fertilizer after being loaded with a weight of 60 kg for one month, and was calculated by the following formula.
Solidification rate (%) of granular fertilizer=(weight of solidified portion after loading for one month)/750×100.

(13) Cohesion Strength of Granular Fertilizer The cohesion strength of granular fertilizer is a value measured by pressing the needle vertically into the upper surface of the fertilizer using a Yamanaka soil hardness tester.

(14) Powderization rate of granular fertilizer The powderization rate of granular fertilizer is obtained by using a sieve with an opening of 2 mm among the granular fertilizer compositions after loading for one month with a weight of 60 kg with respect to 750 g of granular fertilizer. It is the ratio of particles having a grain size of 2 mm or less, and was calculated by the following formula.

Pulverization rate (%) of granular fertilizer=(weight (g) of particles having a particle size of 2 mm or less)/750×100.

In Examples 1 to 10 and Comparative Examples 1 to 6, particles substantially composed of nitrogen fertilizer components shown in Table 1 (denoted as particles A in the table) and particles substantially composed of magnesium fertilizer components (indicated in the table Particles B) were molded to produce a granular fertilizer.

(Example 1)
80 parts by weight of ammonium sulfate particles (particles A) containing 77 wt. 20 parts by weight of particles B) and 0.7 parts by weight of water were supplied to a Dow Mixer (manufactured by Shin-Nichinan Co., Ltd.) as a mixer and mixed for 10 minutes. Next, the mixture was supplied to a Briquette (registered trademark) BSS-IV type (manufactured by Shinto Kogyo Co., Ltd.) as a granulator. After granulating with a pocket size of Φ 3.9 mm × 0.94 mm and a roller rotation speed of 50 rpm, crushing with a coarse crusher, three-stage crushing with sieves with openings of 6.7 mm, 5.2 mm, and 2.2 mm It was put into a sieve machine (manufactured by Kowa Kogyosho) and crushed with crushing media (200 nylon hard balls in the upper stage and 200 in the lower stage). Subsequently, the granulated product was put into a Marumerizer (manufactured by Dalton) and subjected to sieving treatment for 20 seconds at a rotation speed of 225 rpm. ) and classified, and a sieve with an opening of 2 mm was collected as granular fertilizer. The yield of granular fertilizer is 80%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.55 mm, and the ratio of the major axis diameter to the minor axis diameter is (long axis diameter / short axis diameter) is 1.10, 61% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 60% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 79% by weight and the magnesium sulfate content was 20% by weight. In addition, the elution rate ratio of the nitrogen fertilizer component and the magnesium fertilizer component is 1.18, the grain hardness of the granular fertilizer is 3.3 kgf, the bulk density is 0.96 g/ml, the moisture content is 1.0% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.2%.

(Example 2)
70 parts by weight of ammonium sulfate particles (particles A) containing 71 wt. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.9 parts by weight of water were used. The yield of granular fertilizer is 79%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.55 mm, and the ratio of the major axis diameter to the minor axis diameter is (long axis diameter / short axis diameter) is 1.10, 54% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 58% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 69% by weight and the magnesium sulfate content was 30% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.12, the grain hardness of the granular fertilizer is 2.7 kgf, the bulk density is 0.95 g / ml, the moisture content is 1.2% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.3%.

(Example 3)
60 parts by weight of ammonium sulfate particles (particles A) containing 75 wt. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 40 parts by weight of particles B) and 1.2 parts by weight of water were used. The yield of granular fertilizer is 74%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.55 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.10, 58% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 68% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 59% by weight and the magnesium sulfate content was 39% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.14, the grain hardness of the granular fertilizer is 2.4 kgf, the bulk density is 0.95 g / ml, the moisture content is 1.5% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.3%.

(Example 4)
50 parts by weight of ammonium sulfate particles (particles A) containing 73% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate monohydrate particles containing 67% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 50 parts by weight of particles B) and 1.5 parts by weight of water were used. The yield of granular fertilizer is 72%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.50 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.11, 55% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 59% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 49% by weight and the magnesium sulfate content was 49% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.09, the grain hardness of the granular fertilizer is 2.1 kgf, the bulk density is 0.95 g / ml, the moisture content is 1.8% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.6%.

(Example 5)
70 parts by weight of ammonium sulfate particles (particles A) containing 75% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium hydroxide particles (particles B) containing 55% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight and 0.9 parts by weight of water were used. The yield of granular fertilizer is 74%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.50 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.11, 60% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 54% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 69% by weight and the magnesium hydroxide content was 30% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 0.95, the grain hardness of the granular fertilizer is 2.3 kgf, the bulk density is 0.94 g / ml, the moisture content is 1.3% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.4%.

(Example 6)
70 parts by weight of ammonium sulfate particles (particles A) containing 71 wt. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing, and classifying in the same manner as in Example 1, except that parts by weight and water were changed to 0.9 parts by weight. The yield of granular fertilizer is 71%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.40 mm, and the ratio of the major axis diameter to the minor axis diameter is (long axis diameter / short axis diameter) is 1.12, 53% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 57% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 69% by weight and the magnesium chloride content was 30% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.06, the grain hardness of the granular fertilizer is 2.2 kgf, the bulk density is 0.94 g / ml, the moisture content is 1.2% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.5%.

(Example 7)
70 parts by weight of urea particles (particles A) containing 86% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate monohydrate particles containing 70% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.5 parts by weight of water were used. The yield of granular fertilizer is 70%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.40 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.12, 73% by weight of particles A having a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, 65% by weight of particles B having a particle size of more than 0.1 mm and 2 mm or less, The urea content was 70% by weight and the magnesium sulfate content was 29% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.11, the grain hardness of the granular fertilizer is 2.1 kgf, the bulk density is 0.92 g / ml, the moisture content is 1.2% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.9%.

(Example 8)
70 parts by weight of ammonium sulfate particles (particles A) containing 73% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and anhydrous magnesium sulfate particles (particles B) containing 62% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ) 30 parts by weight and 1.5 parts by weight of water were mixed, granulated, pulverized, sized and classified in the same manner as in Example 1 to produce a granular fertilizer. The yield of granular fertilizer is 65%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.50 mm, and the ratio of the major axis diameter to the minor axis diameter is (Long axis diameter / minor axis diameter) is 1.11, 60% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 59% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 69% by weight and the magnesium sulfate content was 30% by weight. In addition, the elution rate ratio of the nitrogen fertilizer component and the magnesium fertilizer component is 1.04, the grain hardness of the granular fertilizer is 2.5 kgf, the bulk density is 0.95 g/ml, the moisture content is 1.7% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.5%.

(Example 9)
70 parts by weight of ammonium sulfate particles (particles A) containing 71% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate trihydrate particles containing 64% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.5 parts by weight of water were used. The yield of granular fertilizer is 62%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.40 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.12, 54% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 52% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 67% by weight and the magnesium sulfate content was 29% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.13, the grain hardness of the granular fertilizer is 2.1 kgf, the bulk density is 0.95 g / ml, the moisture content is 2.1% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.7%.

(Example 10)
70 parts by weight of ammonium sulfate particles (particles A) containing 72% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate heptahydrate particles containing 69% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.2 parts by weight of water were used. The yield of granular fertilizer is 60%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.40 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.12, 52% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 50% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 66% by weight and the magnesium sulfate content was 26% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.19, the grain hardness of the granular fertilizer is 2.0 kgf, the bulk density is 0.95 g / ml, the moisture content is 2.7% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.9%.

(Comparative example 1)
40 parts by weight of ammonium sulfate particles (particles A) containing 77 wt. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 60 parts by weight of particles B) and 0.7 parts by weight of water were used. The yield of granular fertilizer is 51%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.30 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.15, 63% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 61% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 39% by weight and the magnesium sulfate content was 60% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.18, the grain hardness of the granular fertilizer is 0.9 kgf, the bulk density is 0.95 g / ml, the moisture content is 0.9 wt%, After one month of the caking test, the caking rate was 8.1%, the caking strength was 1.8 kg/cm ² , and the pulverization rate was 11.3%.

(Comparative example 2)
70 parts by weight of ammonium sulfate particles (particles A) containing 41 wt. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.9 parts by weight of water were used. The yield of granular fertilizer is 59%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.50 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.09, 35% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 40% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 69% by weight and the magnesium sulfate content was 30% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.19, the grain hardness of the granular fertilizer is 1.5 kgf, the bulk density is 0.95 g / ml, the moisture content is 1.2% by weight, After one month of the caking test, the caking rate was 4.8%, the caking strength was 1.5 kg/cm ² , and the pulverization rate was 1.8%.

(Comparative Example 3)
70 parts by weight of ammonium sulfate particles (particles A) containing 77% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate monohydrate particles containing 11% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.7 parts by weight of water were used. The yield of granular fertilizer is 45%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.8 mm, the minor axis diameter is 3.55 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.07, 65% by weight of particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer, and 15% by weight of particles B with a particle size of more than 0.1 mm and 2 mm or less %, the ammonium sulfate content was 70% by weight and the magnesium sulfate content was 29% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 0.67, the grain hardness of the granular fertilizer is 1.7 kgf, the bulk density is 0.95 g / ml, the moisture content is 1.0% by weight, One month after the caking test, the caking rate was 0%, the caking strength was 0 kg/cm ² , and the pulverization rate was 0.8%.

(Comparative Example 4)
70 parts by weight of ammonium sulfate particles (particles A) containing 9% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and magnesium sulfate particles monohydrate containing 66% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less ( A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying in the same manner as in Example 1 except that 30 parts by weight of particles B) and 0.7 parts by weight of water were used. The yield of granular fertilizer is 31%, the ratio of particle size between 2 mm and 4 mm is 95%, the major axis diameter is 3.6 mm, the minor axis diameter is 3.3 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter / minor axis diameter) is 1.09, particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer are 25% by weight, and particles B with a particle size of more than 0.1 mm and 2 mm or less are 57% by weight. %, the ammonium sulfate content was 69% by weight and the magnesium sulfate content was 30% by weight. In addition, the ratio of the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is 1.64, the grain hardness of the granular fertilizer is 1.0 kgf, the bulk density is 0.94 g / ml, the moisture content is 1.0% by weight, After one month of the caking test, the caking rate was 2.4%, the caking strength was 1.2 kg/cm ² , and the pulverization rate was 5.4%.

(Comparative Example 5)
Mixing, granulation and A granular fertilizer was produced by crushing, sizing, and classifying. The yield of granular fertilizer is 65%, the ratio of particle size between 2 mm and 4 mm is 96%, the major axis diameter is 3.9 mm, the minor axis diameter is 3.55 mm, and the ratio of the major axis diameter to the minor axis diameter is The ratio (major axis diameter/minor axis diameter) was 1.10, and particles A with a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer accounted for 62% by weight. In addition, the grain hardness of the granular fertilizer is 2.8 kgf, the bulk density is 0.96 g / ml, the moisture content is 1.0% by weight, the solidification rate after one month of the solidification test is 3.8%, and the solidification strength is The weight was 0.5 kg/cm ² and the pulverization rate was 0.2%.

(Comparative Example 6)
In the same manner as in Example 1, except that 100 parts by weight of magnesium sulfate monohydrate particles (particles B) containing 63% by weight of particles having a particle size of more than 0.25 mm and 2 mm or less and 0.7 parts by weight of water were used. A granular fertilizer was produced by mixing, granulating, pulverizing, sizing and classifying. The yield of granular fertilizer is 41%, the ratio of particle size between 2 mm and 4 mm is 94%, the major axis diameter is 3.6 mm, the minor axis diameter is 3.0 mm, and the ratio of the major axis diameter to the minor axis diameter is (major axis diameter/minor axis diameter) was 1.20, and particles B having a particle size of more than 0.1 mm and 2 mm or less in the granular fertilizer accounted for 60% by weight. The granular fertilizer had a grain hardness of 0.8 kgf, a bulk density of 0.95 g/ml, a moisture content of 0.9% by weight, a solidification rate of 0% after one month of the solidification test, and a solidification strength of 0 kg/ml. cm ² and the pulverization rate was 27.6%.

Table 1 shows the results.

As described above, the particle size distribution of the particles (particles A) substantially composed of the raw material nitrogen fertilizer component and the particles (particles B) substantially composed of the magnesium fertilizer component, and the quantitative ratio of the particles A and the particles B is within a predetermined range, the elution rate of the nitrogen fertilizer component and the magnesium fertilizer component is uniform, the grain hardness after secondary particle formation is high, and the fertilizer yield after production is high. It can be seen that it is possible to obtain a granular fertilizer that is less likely to be pulverized even during storage and free from caking.

The granular fertilizer according to the present invention does not become pulverized and hardened during storage to reduce fluidity, and can be applied not only by manual fertilization in small farms but also by mechanical spraying in large farms. . In addition, since the bulk blended fertilizer can be prepared by dry-blending the granular fertilizer with other granular fertilizers in an arbitrary ratio according to the application and purpose, it can be used for growing rice, vegetables, fruits, and the like.

Claims (16)

A granular fertilizer in which particles (particles A) substantially composed of a nitrogen fertilizer component and particles (particles B) substantially composed of a magnesium fertilizer component are integrated to form secondary particles, and the particles A have a particle size Particles larger than 0.1 mm and 2 mm or less account for 50% by weight or more of particles A, particles B having a particle size of larger than 0.1 mm and 2 mm or less account for 50% by weight or more of particles B, and A granular fertilizer comprising 50 to 80% by weight of a nitrogen fertilizer component and 20 to 50% by weight of a magnesium fertilizer component in the granular fertilizer. The granular fertilizer according to claim 1, characterized in that the granular fertilizer contains 0.3 to 2.0% by weight of water. The granular fertilizer according to claim 1 or 2, wherein the granular fertilizer has a grain hardness of 2 kgf or more after forming secondary particles. The granular fertilizer according to any one of claims 1 to 3, wherein the ratio of the major axis diameter to the minor axis diameter (major axis diameter / minor axis diameter) is 1.0 or more and 1.4 or less. fertilizer. The granular fertilizer according to any one of claims 1 to 4, wherein the granular fertilizer has a bulk density of 0.9 g/ml or more and 1.1 g/ml or less. The granular fertilizer according to any one of claims 1 to 5, wherein the nitrogen fertilizer component is at least one selected from ammonium sulfate, ammonium chloride, ammonium nitrate, ammonium phosphate and urea. The granular fertilizer according to any one of claims 1 to 6, wherein the magnesium fertilizer component is at least one selected from magnesium sulfate, magnesium chloride, magnesium nitrate, magnesium hydroxide and magnesium carbonate. 8. The magnesium sulfate is at least one selected from the group consisting of magnesium sulfate anhydride, magnesium sulfate monohydrate, magnesium sulfate trihydrate and magnesium sulfate heptahydrate. Granular fertilizer as described. A method for producing a granular fertilizer in which particles (particles A) substantially composed of a nitrogen fertilizer component and particles (particles B) substantially composed of a magnesium fertilizer component are integrated to form secondary particles, comprising: A has a particle size of more than 0.25 mm and 2 mm or less in the particles A, and accounts for 70% by weight or more of the particles A, and the particles B have a particle size of more than 0.25 mm and 2 mm or less. A step of obtaining a mixture by mixing 50 to 80% by weight of particles A and 20 to 50% by weight of particles B in the presence of moisture, with respect to the total weight of the granular fertilizer, which accounts for 50% by weight or more. A method for producing a granular fertilizer, comprising the step of molding the mixture to form secondary particles. 10. The method for producing a granular fertilizer according to claim 9, wherein the granular fertilizer is molded so that the ratio of the major axis diameter to the minor axis diameter is 1.0 or more and 1.4 or less. The method for producing a granular fertilizer according to claim 9 or 10, wherein the granular fertilizer is molded so that the bulk density of the granular fertilizer is 0.9 g/ml or more and 1.1 g/ml or less. The method for producing a granular fertilizer according to any one of claims 9 to 11, wherein the molding method for forming the secondary particles is compression granulation. 13. The method for producing granular fertilizer according to claim 12, wherein the compression granulation is performed by a briquetting method using a pair of rollers. 14. The method for producing a granular fertilizer according to claim 12 or 13, wherein the compression granulation is performed at a granulation pressure of 6.0 kN/cm or more and 30.0 kN/cm or less. The method for producing a granular fertilizer according to any one of claims 9 to 14, wherein compression granulation is performed as the molding step to obtain granules, and then granules are regulated. 16. The method for producing granular fertilizer according to claim 15, wherein the granule sizing is a rotary sizing method.