Method for producing granular ammonium sulfate composition

Abstract

To provide a granular ammonium sulfate composition having high ammonia nitrogen concentration, high particle hardness, and a low solidifying property during storage.SOLUTION: A granular ammonium sulfate composition contains 0.05-0.5 wt.% of a metal sulfate forming a hydrate relative to 100 pts.wt. of the granular ammonium sulfate composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a granular ammonium sulfate composition, a mixed fertilizer composition, and a method for producing a granular ammonium sulfate composition.

Background Art

[0002] Ammonium sulfate, which is one of the nitrogen fertilizers, can be industrially obtained by bringing coke oven waste gas into contact with sulfuric acid, or by crystallizing an ammonium sulfate aqueous solution obtained by adding ammonia to caprolactam sulfate during the production process of caprolactam. The physical properties of ammonium sulfate required as a fertilizer are that "it does not hinder mechanical fertilization", "most of the particle size is within 2 to 4 mm", "the average crushing strength for those with a particle size of 2.0 to 2.8 mm is 2 kgf or more", "the moisture content is 1.0% or less", "the angle of repose is 40° or less", and "it does not have an adverse effect on the physicochemical quality such as caking of the product" (Non-Patent Document 1).

[0003] Powdery and fine-grained ammonium sulfate are not suitable for "not hindering mechanical fertilization", which is an essential requirement as a fertilizer, because the particles are small and easy to fly, resulting in easy dust generation during mechanical spraying and clogging of flow paths. Reducing dust generation during spraying and making it difficult for flow paths to clog are important in fertilization on vast farmlands where mechanical spraying is the mainstream.

[0004] Therefore, in order to overcome these problems, powdery and fine-grained ammonium sulfate are granulated as powdery nitrogen fertilizers, and by increasing the particle size to about 2 to 4 mm, the particle size is large, so the crushing strength is high and the fertilizer has good fluidity. This has been considered.

[0005] For example, in order to provide a granulation method for granulated ammonium sulfate having physical properties suitable for fertilizers such as low impurity, high crushing strength, high nitrogen concentration, and difficulty in caking, a method for granulating nitrogen fertilizer by controlling the pocket size, granulation pressure, and impurity thickness when compression granulating nitrogen fertilizer (Patent Document 1) has been proposed.

[0006] In the production of granular ammonium sulfate, when it is handled as a fertilizer, if "caking" occurs where the granulated ammonium sulfate produced during long-term storage solidifies together, it will deteriorate the workability during mechanical spraying. Therefore, methods for suppressing caking are being studied. For example, when granulating granular fertilizers, a method of adding an anti-caking agent such as wax or a surfactant to a part of the raw materials and then mixing the remaining raw materials and performing compression granulation (Patent Document 2), a method of coating by mixing a solution containing a sugar such as trehalose as a solute with the granular fertilizer to suppress the absorption and release of moisture and prevent caking (Patent Document 3), a method of adding and mixing talc with specified particle size and purity (Patent Document 4), addition of dicyandiamide (Patent Document 5), when performing two-dimensional X-ray diffraction on crystalline ammonium sulfate of the raw materials, using fine-grained crystalline ammonium sulfate with an orientation degree of 0.995 or more at an angle 2θ = 72.3° formed between the direction of the incident X-ray and the direction of the detector as the raw material (Patent Document 6), a method containing 20 to 50% by weight of a magnesium fertilizer component (Patent Document 7), etc. are known.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0009] As described above, various granular nitrogen fertilizers and their manufacturing methods have been proposed. Regarding the caking problem that occurs during the long-term storage of granular ammonium sulfate, preventive measures have been implemented, but sufficient effects have not been obtained. In Patent Document 1, regarding caking prevention, it is described that for granular products, since the particle size is large, the crushing strength is high, and the specific surface area is low, it is difficult for moisture to cause caking. However, if the crushing strength is high and the specific surface area is low, it is not necessarily the case that the moisture is low. If the moisture is high, caking will occur even if the particle size is large. In Patent Document 2, an anti-caking material such as wax or a surfactant is added to a part of the raw ammonium sulfate, and then the remaining ammonium sulfate is mixed and compression granulated to make the surface distribution of the anti-caking material non-uniform to prevent caking. However, this method requires an additional mixing step of the mixture and ammonium sulfate in addition to the mixing step of the anti-caking material and the raw material. In Patent Document 3, a granular nitrogen fertilizer is coated by mixing a solution containing a saccharide such as trehalose as a solute to suppress the absorption and release of moisture to prevent caking. However, when adding an anti-caking material, costs for a mixing step with a solvent for addition and a drying step for evaporating the solvent are required. In Patent Document 4, talc with a particle size of 10 μm or less and a purity of 90% or more is added and mixed as an anti-caking material. However, it is difficult and costly to select or purchase talc of the described quality compared to ordinary talc purchases. In addition, talc usually contains crystalline silica, which is a carcinogenic substance, and selecting the origin of talc and taking dust countermeasures are costly for use. Patent Document 5 describes that caking can be suppressed by adding dicyandiamide, but there is no data description, and the quantitative caking suppression effect cannot be grasped, and the mechanism of caking suppression has not been clarified either.

[0010] Patent Document 6 states that caking can be prevented by using crystal-oriented, highly crystalline fine-grained ammonium sulfate as a raw material, and in order to obtain highly crystalline ammonium sulfate crystals, it is necessary to maintain the pressure during crystallization at 10.1 kPa ABS or higher. However, in general continuous crystallization, the crystal particle size and properties vary, and it is difficult to maintain the operating conditions using crystallinity as an index. Patent Document 7 states that by containing 20 to 50% by weight of a magnesium fertilizer component, the particle hardness is high and caking is less likely to occur. However, since the amount of the magnesium fertilizer is large, the ammonia nitrogen concentration, which is a fertilizer component of ammonium sulfate, decreases, and the fertilizer effect as ammonium sulfate cannot be exhibited.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above problems, the present invention To achieve the above object, the present invention adopts the following configuration. That is, 1. The manufacturing method including the following two steps A granular ammonium sulfate composition containing 0.05 to 0.5% by weight of magnesium sulfate that forms a hydrate with respect to 100 parts by weight of the granular ammonium sulfate composition of . 1) A step of mixing magnesium sulfate forming a hydrate with fine crystalline ammonium sulfate and granulating it into granules 2) A step of sizing the granular ammonium sulfate composition obtained in 1) and adjusting its shape . 2. The manufacturing method of a granular ammonium sulfate composition containing 0.05 to 0.5% by weight of magnesium sulfate forming a hydrate with respect to 100 parts by weight of the granular ammonium sulfate composition, including the following three steps 1) A step of granulating fine crystalline ammonium sulfate into granules 2) A step of sizing the granular ammonium sulfate obtained in 1) and adjusting its shape 3) A step of coating the granular ammonium sulfate with its shape adjusted obtained in 2) with magnesium sulfate forming a hydrate . 3. Contained in the granular ammonium sulfate composition The granular ammonium sulfate composition according to 1, wherein the ammoniacal nitrogen is 20.5% or more or 2 of the manufacturing method . 4. of the granular ammonium sulfate composition The granular ammonium sulfate composition according to 1, wherein the caking strength is 2.0 kg / cm 2 or less any one of ~3 of the manufacturing method . 5. of the granular ammonium sulfate composition The granular ammonium sulfate composition according to 1, wherein the caking rate is 90% or less any one of ~4 of the manufacturing method . 6. of the granular ammonium sulfate composition The granular ammonium sulfate composition according to 1, wherein the particle hardness is 2.0 to 5.0 kgfany one of ~5 The granular ammonium sulfate composition described of the manufacturing method . 7. A method for producing a granular ammonium sulfate composition according to claim any one of 1 to 6 , characterized in that granulation is by a compression molding method 8. A method for producing a granular ammonium sulfate composition according to claim 7 , characterized in that a raw material is compressed by a briquetting method using a pair of rollers to produce a granulated product

Advantages of the Invention

[0012] According to the present invention, by using a granular ammonium sulfate composition containing a very small amount of metal sulfate as an anti-caking agent, a granular ammonium sulfate composition with high ammonia nitrogen, high particle hardness, and difficult to cake during storage can be obtained

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail together with embodiments

[0014] The caking of granular ammonium sulfate occurs when free moisture in the raw material moves to the surface or absorbs moisture in the air, causing the surface to dissolve and recrystallize, and the liquid bridge to become a solid bridge, thereby adhering the particles to each other. Metal sulfates have polarity in their molecular structure and many form hydrates. Therefore, it is considered that hydration suppresses the movement of free moisture and suppresses the formation of bridges between particles. As a result, there is an effect of preventing caking, and by retaining moisture in the particles, a binder effect due to moisture is exerted, and there is also an effect of increasing particle hardness. In addition, metal components such as magnesium and calcium are important components for producing "chlorophyll" in leaves, which is necessary for plant photosynthesis. Metal sulfates such as magnesium sulfate and zinc sulfate are themselves sold as fertilizers and have the function of enhancing the effect as fertilizers

[0015] The granular ammonium sulfate composition of the present invention, by adding a very small amount of metal sulfate that forms a hydrate, such as magnesium sulfate or zinc sulfate, as an anti-caking agent to the raw materials, has a remarkable anti-caking effect while maintaining a high ammonia nitrogen content, has a high grain hardness, and becomes a granular ammonium sulfate composition having a fertilizer effect due to the metal sulfate.

[0016] That is, in the present invention, by coating or mixing a very small amount of a metal sulfate component that forms a hydrate, such as magnesium sulfate or zinc sulfate, with ammonium sulfate and granulating it, while maintaining a high concentration of ammoniacal nitrogen, which is a fertilizer component of ammonium sulfate, caking during storage is suppressed, and due to the high grain hardness, it is difficult to powder and easy to handle and mechanically spread. Furthermore, by including metal sulfates such as magnesium sulfate or zinc sulfate, it becomes possible to obtain a granular ammonium sulfate composition that additionally contains fertilizer components necessary for plant growth.

[0017] <Granular ammonium sulfate composition> The moisture content of the granular ammonium sulfate composition targeted by the present invention is preferably 0.5% or less from the viewpoint of preventing caking between granular ammonium sulfate compositions during long-term storage. More preferably, it is 0.3% or less, still more preferably 0.2% or less, and most preferably 0% when the moisture is completely dried because it does not cake at all. The moisture content of the granular ammonium sulfate composition is a value measured by the loss on ignition method according to the official fertilizer analysis method.

[0018] The ammoniacal nitrogen in the granular ammonium sulfate composition 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.

[0019] The particle size of the granular ammonium sulfate composition is preferably 2.0 to 4.0 mm, more preferably 2.5 to 3.5 mm, in order to ensure the reach distance of the fertilizer in mechanical fertilization.

[0020] When mechanically applying fertilizer, the shape of the granular ammonium sulfate composition is preferably spherical so that it does not adhere to the leaves of crops and falls onto the soil. If it is not spherical, for example, a flat-shaped tablet fertilizer, it will adhere to the leaves and not fall, resulting in poor nutrient supply, which is not preferable. The particle size of the granular ammonium sulfate composition is measured by sieving.

[0021] The particle hardness of the granular ammonium sulfate composition is preferably in the range of 2.0 to 5.0 kgf. If the particle hardness is less than 2.0 kgf, the granular ammonium sulfate composition is likely to powder during production, and the yield during production tends to decrease. Also, powdering is likely to occur during storage of the granular ammonium sulfate composition, causing caking between the granular ammonium sulfate compositions. On the other hand, when the particle hardness exceeds 5.0 kgf, the disintegration property of the granular ammonium sulfate composition in the soil is poor, and the fertilizer effect tends to decrease. More preferably, it is in the range of 2.5 to 4.5 kgf. The particle hardness of the granular ammonium sulfate composition is measured for 20 grains using a wooden hardness meter, and the average value is taken as the particle hardness.

[0022] For easy handling of the granular ammonium sulfate composition, the caking strength is preferably cm 2 as follows. The caking strength is the value measured by vertically pressing the needle part against the upper surface of the fertilizer using a Yamada-type soil hardness meter. Also, the caking rate is preferably 90% or less. If the caking strength is cm 2 as follows, it is usually pseudo-caking, and the caking can be easily broken without problems in fertilization. However, if the caking rate exceeds 90%, the fluidity deteriorates, and there is a possibility that mechanical fertilization cannot be performed, which is not preferable. The caking rate is the ratio of the weight of the caked part in the granular ammonium sulfate composition after one month of loading with an 80 kg weight to 150 g of the granular ammonium sulfate composition, and is represented by the following formula. Caking rate = (Weight of caked part (g) after one month of loading) / 150 × 100

[0023] <Anti-caking agent> The anti-caking agent in the present invention is not particularly limited as long as it is a metal sulfate that forms a hydrate. However, if it is potassium sulfate, magnesium sulfate, calcium sulfate, copper sulfate, zinc sulfate, manganese sulfate, cobalt sulfate, etc., which are used as fertilizer components, the effect as a fertilizer can be expected and it is desirable.

[0024] The addition concentration of the anti-caking agent in the granular ammonium sulfate composition in the present invention preferably contains 0.05 to 0.5% by weight of the metal sulfate that forms a hydrate with respect to 100 parts by weight of the granular ammonium sulfate composition. If it is lower than 0.05% by weight, the effect of preventing caking is low, the effect of increasing the particle hardness is also low, and the effect of the metal sulfate as a fertilizer component is also low. Also, if it exceeds 0.5% by weight, the ammonia nitrogen concentration of the granular ammonium sulfate composition becomes low, and the fertilizer effect when used as an ammonium sulfate fertilizer decreases. Therefore, more preferably, it is 0.1 to 0.3% by weight.

[0025] <Manufacturing method of granular ammonium sulfate composition> As a method for manufacturing the granular ammonium sulfate composition, when mixing the raw material fine crystal ammonium sulfate and the anti-caking agent, the mixing is performed in a mixer. There is no particular limitation on the type of mixer as long as it can be uniformly mixed. Container rotation type mixers such as horizontal cylindrical type, V type, double cone type, etc., and container fixed type mixers such as ribbon type, screw type, paddle type, etc. can be used. However, since continuous processing is possible, the paddle type mixer is preferably used.

[0026] The granulation method of the granular ammonium sulfate composition is preferably compression granulation. There is no problem with using any of the tablet method, plate method, and briquette method for the compression granulation device. However, in the tablet method, the production efficiency is low and it is difficult to mass-produce the granular ammonium sulfate composition. Also, in the plate method, it is difficult to produce granulated fertilizer with a spherical shape and few burrs. Therefore, it is preferable to use the briquette method. As the compression granulation device of the briquette method, for example, the briquettor (registered trademark) BSS type (manufactured by Shin-Tong Industry Co., Ltd.) can be preferably used.

[0027] The method of supplying the fine-grained crystalline ammonium sulfate mixture mixed with the raw material fine-grained crystalline ammonium sulfate and the anti-caking agent to the compression granulation device is not particularly limited. For example, the fine-grained crystalline ammonium sulfate can be stored in a hopper and directly supplied to the granulation device from the conveying conveyor attached to the hopper, or supplied to the granulation device via a belt conveyor, a bucket conveyor, etc. from the hopper conveying conveyor.

[0028] The granulation pressure indicates the value (linear pressure) obtained by dividing the total load applied to the fine-grained crystalline ammonium sulfate mixture of the raw material by the effective width. The effective width indicates the major axis on the compressor side in the portion where the load is applied to the fine-grained crystalline ammonium sulfate mixture of the raw material. For example, in the case of the tablet method, the effective width is the major axis of the tablet portion, and in the case of the briquette method using rollers, the effective width is the length of the portion where the fine-grained crystalline ammonium sulfate mixture of the raw material is compressed by the rollers. The granulation pressure is preferably in the range of 0.6 to 30.0 kN / cm, more preferably 3.0 to 20.0 kN / cm, and still more preferably 5.0 to 15.0 kN / cm. When the granulation pressure is lower than the above range, granulation of the fine-grained crystalline ammonium sulfate mixture does not occur due to insufficient pressure. When the granulation pressure is higher than the above range, an excessive load is applied to the compression granulator, resulting in a significant reduction in the device life.

[0029] The burr thickness of the compression granulator indicates the minor axis of the fine-grained crystalline ammonium sulfate mixture of the raw material in the portion where the load is applied to the fine-grained crystalline ammonium sulfate mixture of the raw material. For example, in the case of the tablet method, the burr thickness is the minor axis of the tablet portion, and in the case of the briquette method using rollers, the burr thickness is the shortest length of the roll gap (clearance). The burr thickness is preferably in the range of 1.00 to 2.50 mm, and more preferably in the range of 1.20 to 2.00 mm. When the burr thickness is lower than the above range, both the crushing strength and the yield of the granular ammonium sulfate composition tend to decrease. When the burr thickness is higher than the above range, the shape of the granular ammonium sulfate composition becomes unsuitable for fertilizer spreading, and when the granulated granular ammonium sulfate composition is crushed with a vibrating sieve using, for example, crushing balls to make the particle sizes uniform, it causes clogging of the sieve, which is not preferable.

[0030] The granular ammonium sulfate composition granulated by a compression granulator can obtain a granular ammonium sulfate composition with a preferable shape as a fertilizer by performing crushing, sizing, and classification.

[0031] In order to obtain a granular ammonium sulfate composition with uniform particle size, it is preferable to crush the granular ammonium sulfate composition after compression granulation using a crusher. There is no particular limitation on the type of crusher. For example, various crushers such as jaw crushers and roll crushers, various mills such as roller mills and cutting mills, and vibrating sieves with added crushing media are preferably used. It is also possible to use these crushers in combination.

[0032] In order to obtain a granular ammonium sulfate composition that is spherical and has few burrs, it is preferable to perform sizing using a sizing machine. There is no particular limitation on the type of sizing machine. For example, high-speed rolling methods, oscillator types, crushing methods, centrifugal rotation methods, etc. are preferably used, and it is more preferable to size the granular ammonium sulfate composition using a Marumerizer (registered trademark: manufactured by Dalton), which is a spherical sizing machine using the high-speed rolling method.

[0033] The processing time of the sizing machine is preferably in the range of 0.2 to 5.0 minutes, and more preferably in the range of 0.3 to 3.0 minutes. If the processing time of the sizing machine is lower than the above range, the removal of burrs from the granular ammonium sulfate composition will be insufficient. If the processing time of the sizing machine is higher than the above range, the amount of parts other than burrs cut will increase, resulting in a decrease in the yield of the granular ammonium sulfate composition. Furthermore, since the time required for the sizing process increases, the yield of the granular ammonium sulfate composition per unit time also decreases.

[0034] The rotational speed of the sizing machine is preferably in the range of 50 to 2000 revolutions per minute, and more preferably in the range of 100 to 1500 revolutions per minute. If the rotational speed of the sizing machine is lower than the above range, the removal of burrs from the granular ammonium sulfate composition will be insufficient, and since the time required for the sizing process increases, the yield of the granular ammonium sulfate composition per unit time also decreases. If the rotational speed of the sizing machine exceeds the above range and becomes too high, problems such as increased noise and reduced equipment life will occur.

[0035] In order to obtain a granular ammonium sulfate composition with a particle size equal to or larger than a predetermined value, it is desirable to classify the granular ammonium sulfate composition using a classifier. If dry classification is possible, there is no particular limitation on the type of classifier, but it is preferable to use a vibrating sieve. The mesh opening of the sieve is not particularly limited as long as it can obtain a predetermined particle size, but it is preferably 1.8 - 2.2 mm and 3.8 - 4.2 mm, and a classification method of combining sieves with these mesh openings to obtain a granular ammonium sulfate composition with a particle size of 2.0 - 4.0 mm is preferable.

[0036] In order to obtain a granular ammonium sulfate composition with few burrs, high crushing strength, high nitrogen concentration, little generation of dust, and difficult caking, granulate a fine-grained crystalline ammonium sulfate mixture as a raw material using a compression granulator, crush the granular ammonium sulfate composition after compression granulation using a crusher, size the granular ammonium sulfate composition after crushing using a spherical sizing machine, and then classify the sized granular ammonium sulfate composition using a classifier.

[0037] There is no limitation on the transportation method of the granular ammonium sulfate composition in each process, but it is possible to use natural fall, conveyor transportation, pneumatic transportation, etc. It is preferable to transport the raw material to the granulator by conveyor transportation and then transport it to the crusher, sizing machine, and classifier by natural fall. For the powder-contact parts of the equipment including these transportation devices, it is preferable to use a material with corrosion resistance to the granular ammonium sulfate composition, and it is preferable to use SUS316L or resin.

[0038] When granulating a fine-grained crystalline ammonium sulfate mixture as a raw material using a compression granulator, crushing the granular ammonium sulfate composition after compression granulation using a crusher, sizing the granular ammonium sulfate composition after crushing using a sizing machine, and classifying the sized granular ammonium sulfate composition using a classifier, the fine powder under the sieve obtained can be recycled and mixed with the raw material and used as a raw material.

[0039] When coating instead of mixing the anti-caking agent, after granulating and sizing fine-grained crystalline ammonium sulfate to produce granular ammonium sulfate, a metal sulfate that forms a hydrate can be coated on the surface of the granular ammonium sulfate as an anti-caking agent to obtain a granular ammonium sulfate composition fertilizer. As a coating method, if the granular ammonium sulfate is granulated, sized, and uniformly coated after being classified by a classifier, it may be added at the classifier outlet, or it may be mixed and coated using a mixer, or it may be coated by spraying on a belt conveyor.

[0040] The addition amount of the anti-caking agent to the granular ammonium sulfate composition is preferably 0.05 to 0.5% by weight based on 100 parts by weight of the granular ammonium sulfate composition. There is no influence on the loss due to adhesion to the apparatus and the nitrogen content per unit weight. In order to obtain a fertilizer with a granular hardness that is easily disintegrated as a fertilizer, 0.1 to 0.2% by weight is more preferable based on 100 parts by weight of the granular ammonium sulfate composition.

[0041] After granulating and sizing to produce a granular ammonium sulfate composition, it is also possible to dry the granular ammonium sulfate composition to reduce the moisture content. There are no particular restrictions on the type of dryer, and hot air heating dryers such as rotary dryers and fluidized bed dryers, and conduction heat transfer dryers such as stirring dryers and infrared heating dryers are used. However, since the introduction cost of the dryer is low and a sizing effect due to rotation during drying can be seen, a rotary dryer is preferably used. The drying temperature is preferably 60 to 150°C, more preferably 100 to 130°C. If the drying temperature is lower than the above range, the moisture reduction by drying becomes insufficient, resulting in a long drying time, leading to pulverization inside the apparatus and deterioration of productivity. If the drying temperature is higher than the above range, decomposition of the granular ammonium sulfate composition causes a decrease in the ammonia nitrogen concentration. The drying time is preferably 5 to 60 minutes, more preferably 10 to 30 minutes. If the drying time is lower than the above range, the drying effect is low and the moisture reduction is insufficient. If the drying time is higher than the above range, long-time heating causes pulverization inside the apparatus and deterioration of productivity.

Example

[0042] Examples of the present invention are shown below, but the present invention is not limited to only the following examples. Here, the parts in the examples indicate parts by weight. The measurement methods for physical properties and the like are as follows.

[0043] (1) Granular hardness of the granular ammonium sulfate composition It is the value obtained by measuring the granular hardness of each of 20 grains of the granular ammonium sulfate composition with a wooden hardness tester and obtaining the average.

[0044] (2) Ammoniacal nitrogen It is the value measured by the formaldehyde method in which ammonium ions are made into hexamine and the free acid is titrated among the ammoniacal nitrogen measurement methods defined in the official fertilizer analysis method.

[0045] (3) Moisture content of the granular ammonium sulfate composition The moisture content of the granular ammonium sulfate composition is the value obtained by determining the weight loss on heating when the granular ammonium sulfate composition before drying is dried at 130 °C for 3 hours and then weighed, and is calculated by the following formula. Moisture content (%) = (weight of granular ammonium sulfate composition before drying - weight of granular ammonium sulfate composition after drying) / (weight of granular ammonium sulfate composition before heating) × 100

[0046] (4) Caking strength of the granular ammonium sulfate composition It is the value measured by using a Yamada type soil hardness tester and vertically pressing the needle part onto the upper surface of the fertilizer.

[0047] (5) Caking rate of the granular ammonium sulfate composition It is the ratio of the weight of the caked part in the granular ammonium sulfate composition after loading with an 80 kg weight for one month with respect to 150 g of the granular ammonium sulfate composition, and is calculated by the following formula. Caking rate (%) = (weight of caked part (g) after loading for one month) / 150 × 100

[0048] (Example 1) 0.1 part by weight of magnesium sulfate monohydrate was added to 99.9 parts by weight of fine crystalline ammonium sulfate, and the mixture was supplied to a Dow mixer (manufactured by Shin-Nichinan Co., Ltd.) as a mixer and mixed. The raw material was supplied to a Briquetta (registered trademark) BSS-IH type (manufactured by Shin-Tokyo Industries Co., Ltd.) as a granulator, and granulation was carried out at a roll effective width of 185 mm, a roll pressure of 8.3 kN / cm, a burr thickness of 1.70 mm, a pocket size of 3.9 mm × 0.94 mm, and a roller rotation speed of 85 rpm. After crushing with a crusher, it was put into a three-stage crushing and screening machine (manufactured by Kowa Kogyosho) having sieves with mesh openings of 6.7 mm, 5.2 mm, and 2.2 mm, crushed with crushing media (200 nylon hard balls in the upper stage and 200 in the lower stage), and the screened product was recovered. Subsequently, the screened and crushed product was put into a marumerizer (manufactured by Dalton), subjected to sizing treatment at a rotation speed of 225 rpm for 15 seconds, then sent to a circular vibrating screen machine (manufactured by Dalton) having a sieve with a mesh opening of 2 mm, classified, and the screened product with a mesh opening of 2 mm was recovered as a granular ammonium sulfate composition. The ammoniacal nitrogen in the granular ammonium sulfate composition was 21.1%, the moisture content was 0.1%, the grain hardness was 3.2 kgf, the caking rate after 1 month of the caking test was 0.0%, and the caking strength was 0.0 kg / cm 2 It was. The results are shown in Table 1.

[0049]

Table 1

[0050] (Example 2) 0.2 part by weight of magnesium sulfate monohydrate was added to 99.8 parts by weight of fine crystalline ammonium sulfate, and the mixture was supplied to a Dow mixer (manufactured by Shin-Nichinan Co., Ltd.) as a mixer and mixed. Then, a granular ammonium sulfate composition was produced in the same manner as in Example 1. The ammoniacal nitrogen in the granular ammonium sulfate composition was 21.1%, the moisture content was 0.1%, the grain hardness was 3.4 kgf, the caking rate after 1 month of the caking test was 0.0%, and the caking strength was 0.0 kg / cm 2 It was.

[0053] (Example 5) 100 parts by weight of fine crystalline ammonium sulfate was used as a raw material. The raw material was supplied to a briquetter (registered trademark) BSS-IH type (manufactured by Shin-Tokyo Industries Co., Ltd.) as a granulator, and granulation was carried out at a roll effective width of 185 mm, a roll pressure of 8.3 kN / cm, a bar thickness of 1.70 mm, a pocket size of 3.9 mm × 0.94 mm, and a roller rotation speed of 85 rpm. After crushing with a crusher, it was put into a three-stage crushing and screening machine (manufactured by Kowa Kogyosho Co., Ltd.) having sieves with mesh openings of 6.7 mm, 5.2 mm, and 2.2 mm, crushed with crushing media (200 upper and 200 lower nylon hard balls), and the screened product was recovered. Subsequently, the screened and crushed product was put into a marumerizer (manufactured by Dalton), subjected to sizing treatment at a rotation speed of 225 rpm for 15 seconds, then sent to a circular vibrating sieve machine (manufactured by Dalton) having a sieve with a mesh opening of 2 mm, classified, and the screened product with a mesh opening of 2 mm was recovered as granular ammonium sulfate. 0.2 part by weight of magnesium sulfate monohydrate was added to 99.8 parts by weight of granular ammonium sulfate in the recovery section of the circular vibrating sieve process to coat the surface of the granular ammonium sulfate. The ammoniacal nitrogen of this granular ammonium sulfate composition was 21.1%, the moisture content was 0.2%, the grain hardness was 2.6 kgf, the caking rate after 1 month of the caking test was 82%, and the caking strength was 1.6 kg / cm 2 It was.

[0055] (Comparative Example 1) Granular ammonium sulfate was produced in the same manner as in Example 5. The coating treatment of trace components was not performed. The ammoniacal nitrogen of this granular ammonium sulfate was 21.2%, the moisture content was 0.2%, the grain hardness was 1.8 kgf, the caking rate after 1 month of the caking test was 99%, and the caking strength was 8.5 kg / cm 2 It was.

[0056] (Comparative Example 2) After producing granular ammonium sulfate in the same manner as in Example 5, 0.2 part by weight of talc (Asada Flour SW-A) was added to 99.8 parts by weight of granular ammonium sulfate in the circular vibrating sieve process to coat the surface of the granular ammonium sulfate with talc. The ammoniacal nitrogen of this granular ammonium sulfate composition was 21.1%, the moisture content was 0.1%, the grain hardness was 2.0 kgf, the caking rate after 1 month of the caking test was 98%, and the caking strength was 7.4 kg / cm 2 It was.

[0057] (Comparative Example 3) 96 parts by weight of fine crystalline ammonium sulfate and 4 parts by weight of magnesium sulfate monohydrate were supplied to a Dow mixer (manufactured by Shin Nissha Co., Ltd.) as a mixer and mixed. The raw materials were supplied to a Briccetta (registered trademark) BSS-IH type (manufactured by Shin-Tokyo Industries Co., Ltd.) as a granulator, and granulation was carried out with a roll effective width of 185 mm, a roll pressure of 8.3 kN / cm, a burr thickness of 1.70 mm, a pocket size of 3.9 mm × 0.94 mm, and a roller rotation speed of 85 rpm. After crushing with a crusher, it was put into a three-stage crushing and screening machine (manufactured by Kowa Kogyosho) having sieves with openings of 6.7 mm, 5.2 mm, and 2.2 mm, crushed with crushing media (200 nylon hard balls in the upper stage and 200 in the lower stage), and the screened product was recovered. Subsequently, the screened and crushed product was put into a marumerizer (manufactured by Dalton), subjected to a sizing treatment at a rotational speed of 225 rpm for 15 seconds, then sent to a circular vibrating screen machine (manufactured by Dalton) having a sieve with an opening of 2 mm, classified, and the screened product with an opening of 2 mm was recovered as a granular ammonium sulfate composition. The ammoniacal nitrogen in the granular ammonium sulfate composition was 20.4%, the moisture content was 0.2%, the grain hardness was 3.5 kgf, the caking rate after 1 month of the caking test was 0.0%, and the caking strength was 0.0 kg / cm 2 It was.

Industrial Applicability

[0058] According to the present invention, using fine crystalline ammonium sulfate as a raw material, it is possible to obtain a granular ammonium sulfate composition having a high grain hardness and low caking property during storage while maintaining a high ammoniacal nitrogen concentration as a fertilizer component, which facilitates handling as a fertilizer and mechanical spraying.

Claims

**Claim 1**: A method for producing a granular ammonium sulfate composition, comprising the following two steps and containing 0.05 to 0.5% by weight of magnesium sulfate that forms a hydrate based on 100 parts by weight of the granular ammonium sulfate composition. 1) A step of mixing magnesium sulfate that forms a hydrate with fine crystalline ammonium sulfate and granulating it into granules 2) A step of sizing the granular ammonium sulfate composition obtained in 1) and adjusting its shape. **Claim 2**: A method for producing a granular ammonium sulfate composition, comprising the following three steps and containing 0.05 to 0.5% by weight of magnesium sulfate that forms a hydrate based on 100 parts by weight of the granular ammonium sulfate composition. 1) A step of granulating fine crystalline ammonium sulfate into granules 2) A step of sizing the granular ammonium sulfate obtained in 1) and adjusting its shape 3) A step of coating the granular ammonium sulfate with adjusted shape obtained in 2) with magnesium sulfate that forms a hydrate. **Claim 3**: The method for producing a granular ammonium sulfate composition according to claim 1 or 2, wherein the ammoniacal nitrogen contained in the granular ammonium sulfate composition is 20.5% or more.

4. The granulated ammonium sulfate composition has a consolidation strength of 2.0 kg / cm ２ The method for producing a granulated ammonium sulfate composition according to any one of claims 1 to 3, wherein the consolidation strength is 2.0 kg / cm or less. **Claim 5**: The method for producing a granular ammonium sulfate composition according to any one of claims 1 to 4, wherein the caking rate of the granular ammonium sulfate composition is 90% or less. **Claim 6**: The method for producing a granular ammonium sulfate composition according to any one of claims 1 to 5, wherein the particle hardness of the granular ammonium sulfate composition is 2.0 to 5.0 kgf. **Claim 7** The method for producing a granular ammonium sulfate composition according to any one of claims 1 to 6, characterized in that the granulation is by a compression molding method. **Claim 8** The method for producing a granular ammonium sulfate composition according to claim 7, characterized in that the raw material is compressed by a briquetting method using a pair of rollers to produce a granulated product.

Images