Manufacturing method of granular fertilizer

Abstract

To provide a simple and efficient manufacturing method of a granular fertilizer without burning at high temperature or neutralization of a raw material.SOLUTION: A manufacturing method of a granular fertilizer, when manufacturing the granular fertilizer including burned ash that contains 0.0 wt.% or more and 15.0 wt.% or less of potassium, includes the following four steps of: 1) mixing water without adding acid to burned ash that contains 0.0 wt.% or more and 15.0 wt.% or less of potassium; 2) drying the mixture obtained in 1); 3) pelletizing the dried mixture obtained in 2) to be made granular; and 4) drying the granulated substance obtained in 3).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a simple and efficient granular fertilizer using incineration ash with a low potassium content, such as sewage sludge incineration ash, as a raw material.

Background Art

[0002] Incineration ash contains phosphorus and the like, and a number of patents have been filed for technologies for effectively utilizing the ash to produce fertilizers and the like. For example, Patent Document 1 discloses a method for producing a granular fertilizer in which 7% to 15% of water is added to and mixed with chicken manure combustion ash to granulate the ash, in order to produce a granulating material more simply and efficiently in the technology for producing a granulating material using chicken manure combustion ash. Further, Patent Documents 2 and 3 disclose a method for producing a phosphoric acid fertilizer that can contribute to phosphorus resource saving and energy saving by firing a raw material containing sewage sludge and / or its derivatives and livestock manure and / or its derivatives as a calcium source to produce a phosphoric acid fertilizer.

[0003] Further, Patent Document 4 discloses a method for producing a granular fertilizer in which alkaline chicken manure combustion ash is neutralized with phosphoric acid to obtain neutralized ash, water and talc are added to the obtained neutralized ash as a granulation promoting material, mixed, and granulated in order to obtain a granular fertilizer composition that is easy to handle and can withstand mechanical spraying.

[0004] Furthermore, Patent Document 5 discloses a method for producing a granular fertilizer in which, as a method for preventing the raw material from adhering to a conveyor device such as a belt conveyor or a granulator for producing a granular fertilizer during granulation processing or from solidifying during storage and reducing fluidity, water, an acidic aqueous solution, and a binder are added to chicken manure combustion ash, kneaded, and then granulated using a raw material dried by a rolling hot air drying method until the moisture content becomes 3% or less.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] As mentioned above, a method for producing granular fertilizer using incinerated ash as a raw material has been proposed, but the manufacturing process is complex and requires large-scale equipment, including high-temperature firing and neutralization of the raw materials. There is a need for a simpler and more efficient method for producing granular fertilizer. [Means for solving the problem]

[0007] As a result of diligent research to solve the aforementioned problems, the present invention has found a simple and efficient manufacturing method that allows for the production of granular fertilizer without high-temperature firing or neutralization of the raw materials, by using incinerated ash with a potassium content of 15.0% by weight or less as a raw material.

[0008] To achieve the above objective, the present invention employs the following configuration. 1. A method for producing granular fertilizer containing incinerated ash with a potassium content of 0.0% by weight or more and 15.0% by weight or less, comprising the following four steps. 1) A process of mixing water with incinerated ash having a potassium content of 0.0% by weight or more and 15.0% by weight or less, without adding acid. 2) A step of drying the granular fertilizer composition obtained in step 2) 3) The process of granulating the granular fertilizer composition obtained in step 3) into granules. 4) A drying process of the granules obtained in step 3). A method for producing granular fertilizer according to claim 1, characterized by including a step of adjusting the shape after step 2.3) or 4). A method for producing granular fertilizer according to 1 or 2, characterized in that one or more other fertilizer components or granulation accelerators are added in step 3.1). 4. The method for producing granular fertilizer according to claim 3, characterized in that the other fertilizer components include at least one fertilizer component selected from nitrogen fertilizer components, phosphorus fertilizer components, and potassium fertilizer components. 5. The method for producing granular fertilizer according to claim 3 or 4, characterized in that the nitrogen fertilizer component includes at least one selected from ammonium sulfate, ammonium chloride, ammonium nitrate, and urea. 6. The method for producing granular fertilizer according to 3 or 4, characterized in that the phosphorus fertilizer component includes at least one selected from monoammonium phosphate or diammonium phosphate, superphosphate, super superphosphate, and fused phosphate fertilizer. 7. The method for producing granular fertilizer according to claim 3 or 4, characterized in that the potassium fertilizer component includes at least one selected from potassium sulfate, potassium chloride, potassium nitrate, and potassium silicate. 8. A method for producing granular fertilizer according to claim 3, characterized in that the granulation accelerator is an aqueous solution obtained by dissolving at least one selected from molasses, starch, carboxymethylcellulose, and lignin sulfonate in water. A method for producing granular fertilizer according to any one of claims 1 to 8, wherein the amount of water added in step 9.1) is 10.0 parts by weight or more and 30.0 parts by weight or less per 100 parts by weight of a mixture of incinerated ash and one or more fertilizer components or granulation accelerators. A method for producing granular fertilizer according to any one of 1 to 9, characterized in that in step 10.2), the moisture content is dried to 1.0% by weight or more and 10.0% by weight or less. A method for producing granular fertilizer according to any one of 1 to 10, characterized in that the granulation in step 11.3) is performed by compressing and granulating the raw material using a briquette method with a pair of rollers. A method for producing granular fertilizer according to any one of 1 to 11, characterized in that in step 12.4), the fertilizer is dried to a moisture content of less than 1.0% by weight. [Effects of the Invention]

[0009] According to the present invention, granular fertilizer can be produced without high-temperature firing or neutralization of raw materials, making it a simple and efficient manufacturing method. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below, along with its embodiments.

[0011] <Incineration ash> Incineration ash refers to ash obtained by incinerating sewage sludge, which is removed by sedimentation or filtration during various stages of wastewater and sewage treatment, after concentration, pre-dewatering, and dewatering, as well as manure from poultry such as chickens, ducks, and geese, and livestock such as pigs, cattle, horses, goats, sheep, dogs, and cats. Of these, incineration ash that contains phosphorus, an effective component for fertilizer, and does not contain potassium or has a potassium content of 15.0% by weight or less is used. It is more preferable that the potassium content is between 1.0% by weight and 13.0% by weight. Examples of such incineration ash include sewage sludge incineration ash.

[0012] <Method for producing granular fertilizer> By using the incinerated ash described above, granular fertilizer can be produced without a neutralization step. The present invention's method for producing granular fertilizer containing incinerated ash with a potassium content of 15.0% by weight or less consists of the following four steps.

[0013] <Manufacturing process 1> A step of mixing water with the incineration ash without adding an acid. The amount of water added is preferably 8.0 parts by weight or more and 35.0 parts by weight or less per 100 parts by weight of the mixture in which one or more of a fertilizer component or a granulation accelerator are mixed with the incineration ash in order to moisten the incineration ash, facilitate handling, and improve the binder effect in granulation. More preferably, it is 10.0 parts by weight or more and 30.0 parts by weight or less. Even more preferably, it is 10.0 parts by weight or more and 20.0 parts by weight or less. The mixing method of the incineration ash, the fertilizer component or the granulation accelerator and water may be premixed using a mixer in advance or mixed in a granulator as long as they are uniformly mixed. There is no particular limitation on the type of mixer as long as uniform mixing can be achieved, and container-rotating mixers such as horizontal cylindrical type, V-type, double-cone type, etc., and container-fixed mixers such as ribbon type, screw type, paddle type, etc. can be used, but a paddle type mixer is preferably used because continuous processing is possible. The mixing time is preferably 5 minutes or more and 15 minutes or less, and more preferably 5 minutes or more and 10 minutes or less. If the mixing time is shorter than 5 minutes, different raw materials in the mixture will not be uniformly dispersed, and raw material deviation will occur during granulation. If the mixing time exceeds 15 minutes and becomes too long, it will be economically disadvantageous because the capacity of the mixer will be increased in the continuous production of fertilizers.

[0014] <Manufacturing Process 2> A step of drying the granular fertilizer composition obtained in Manufacturing Process 1. In the present invention, the granular fertilizer composition refers to a mixture obtained by adding water to a mixture in which one or more of a fertilizer component or a granulation accelerator are mixed with the incineration ash. There are two types of granular fertilizer compositions: one obtained by adding and mixing water and a granulation accelerator to the incineration ash (granular fertilizer composition 1), and the other obtained by adding and mixing water and a fertilizer component to the incineration ash (granular fertilizer composition 2).

[0015] By drying the granular fertilizer composition, it can be made into a granular fertilizer composition that does not adhere to the conveying equipment when used as a granulation raw material and does not solidify during raw material storage and reduce fluidity.

[0016] The granular fertilizer composition is preferably dried using a dryer. 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 can be used. However, due to the low introduction cost of the dryer, the possibility of continuous processing, and the ease of controlling the particle size of the granular fertilizer composition, a rotary hot air dryer is preferably used. The drying temperature is preferably 60°C or higher and 150°C or lower, more preferably 100°C or higher and 130°C or lower. If the drying temperature is lower than 60°C, the reduction of moisture by drying becomes insufficient, resulting in a long drying time, causing pulverization inside the device and deterioration of productivity. If the drying temperature exceeds 150°C for a long time, it will cause discoloration of the fertilizer. The drying time is preferably 5 minutes or more and 60 minutes or less, more preferably 10 minutes or more and 30 minutes or less. If the drying time is shorter than 5 minutes, the drying effect is low and the reduction of moisture is insufficient. If the drying time exceeds 60 minutes, pulverization will occur inside the device due to long-term heating, resulting in a decrease in productivity. Drying is carried out until the moisture content of the granular fertilizer composition becomes 1.0% by weight or more and 10.0% by weight or less. More preferably, the drying is until the moisture content of the granular fertilizer composition becomes 1.0% by weight or more and 7.0% by weight or less. Even more preferably, the drying is until 1.0% by weight or more and 3.5% by weight or less.

[0017] <Manufacturing Process 3> A step of granulating the dried granular fertilizer composition obtained in Manufacturing Process 2 into granules. The granulation method of the granular fertilizer preferably uses compression granulation. There is no problem in 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 granular fertilizers. Also, in the plate method, it is difficult to produce granular fertilizers 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, a briquetter (registered trademark) BSS type (manufactured by Shin To Kogyo) can be preferably used.

[0018] The method of supplying the granular fertilizer composition to the compression granulator is not particularly limited, but for example, it can be stored in a hopper and supplied directly to the granulator via a conveyor attached to the hopper, or supplied to the granulator via a belt conveyor or bucket conveyor from the hopper conveyor.

[0019] Granulation pressure refers to the value (linear pressure) obtained by dividing the total load applied to the granular fertilizer composition by the effective width, and the effective width refers to the longest diameter on the compressor side of the part of the granular fertilizer composition where the load is applied. For example, in the tablet method, the effective width is the longest diameter of the tablet portion, and in the briquette method using rollers, the effective width is the length of the part where the granular fertilizer composition is compressed by the rollers. The granulation pressure is preferably within the range of 0.6 to less than 30.0 kN / cm in terms of roll pressure. If the granulation pressure is lower than the above, granulation of the granular fertilizer composition will not occur due to insufficient pressure. If the granulation pressure is higher than the above, an excessive load will be placed on the compression granulator, significantly reducing the lifespan of the equipment.

[0020] The burr thickness of a compression granulator refers to the short diameter of the granular fertilizer composition in the area where the load is applied. For example, in the tablet method, the burr thickness is the short diameter of the tablet portion, and in the briquette method using rollers, the burr thickness is the length of the thickness of the plate-like portion of the granulated material obtained by granulation. The burr thickness is preferably in the range of 1.0 mm to 2.5 mm, and more preferably in the range of 1.2 mm to 2.0 mm. If the burr thickness is less than 1.2 mm, both the crushing strength and 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 if the granulated fertilizer is crushed and the particle size is standardized using, for example, a vibrating sieve with crushing balls, it can cause clogging of the sieve, which is undesirable.

[0021] To obtain granular fertilizer with few burrs, high crush strength, low dust generation, and resistance to caking during product storage, it is preferable to granulate the raw materials using a compression granulator, crush the granulated material after compression granulation using a crusher, dry it using a dryer, size the granulated material using a spherical granulator, and classify the sized granular fertilizer 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 drop, conveyor transport, or air transport. It is preferable to transport the granulation raw materials to the granulator by conveyor, and then transport them by gravity drop to the crusher, dryer, spherical granulator, and classifier. For the parts of the equipment, including these transport devices, that come into contact with powder, it is preferable to use materials that are corrosion-resistant to granular fertilizer, and it is preferable to use SUS316L or resin.

[0022] Granular fertilizer produced using a compression granulator can be crushed, dried, sized, and classified to obtain spherical granules suitable for use as fertilizer.

[0023] To obtain granular fertilizer with uniform particle size, it is preferable to crush the granular fertilizer after compression granulation using a crusher. There are no particular restrictions 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 screens with crushing media added are preferably used. It is also possible to use a combination of these crushers.

[0024] <Manufacturing process 4> This step involves drying the granules obtained in manufacturing step 3. To obtain granular fertilizer with a high yield when granulated, low amount of solidification during storage, and minimal powdering, it is preferable to reduce the moisture content using a dryer. There are no particular restrictions on the type of dryer; hot air receiving dryers such as tumbling dryers and fluidized bed dryers, and conduction heat transfer dryers such as agitation dryers and infrared heating dryers can be used. However, tumbling dryers are preferred because they have low introduction costs and allow for continuous processing. The drying temperature is preferably 60°C to 150°C, and more preferably 100°C to 130°C. If the drying temperature is lower than 60°C, the moisture reduction by drying will be insufficient, requiring a long drying time and leading to powdering inside the equipment and a decrease in productivity. If the drying temperature is higher than 150°C, the decomposition of the granular fertilizer will cause a decrease in the concentration of fertilizer components. The drying time is preferably 5 minutes to 60 minutes, and more preferably 10 minutes to 30 minutes. If the drying time is shorter than 5 minutes, the drying effect is low and moisture reduction is insufficient. If the drying time is longer than 60 minutes, pulverization occurs inside the device due to prolonged heating, reducing productivity. When drying granular fertilizer, it is preferable to dry it until the moisture content of the granular fertilizer is 1.0% by weight or less. From the viewpoint of preventing the granular fertilizer from clumping together during long-term storage, it is more preferable to dry it until the moisture content is 0.5% by weight or less, and it is most preferable when the moisture content is 0.0% by weight, as this has the lowest possibility of clumping.

[0025] <Whole grain and grading> To obtain spherical granular fertilizer with few burrs, it is preferable to use a granular sizing machine to sizing the fertilizer. The timing of sizing is preferably after manufacturing process 3 or manufacturing process 4. After drying, granular hardness improves, powdering during sizing is less likely to occur, and yield is improved, so it is even more preferable to sizing after drying (after manufacturing process 4). There are no particular restrictions on the type of granular sizing machine, but for example, high-speed rolling method, oscillator type, crushing method, centrifugal rotation method are preferably used, and it is even more preferable to use a high-speed rolling type spherical granular sizing machine such as Marmelizer (registered trademark: manufactured by Dalton) to sizing the granular fertilizer.

[0026] The processing time of the granulation machine is preferably within the range of 0.3 to 5.0 minutes, and more preferably within the range of 0.5 to 3.0 minutes. If the processing time of the granulation machine is lower than the above, the removal of burrs from the granular fertilizer will be insufficient. If the processing time of the granulation machine is higher than the above, the amount of material other than burrs that is cut off increases, and the yield of granular fertilizer decreases. Furthermore, since the time required for granulation processing increases, the yield of granulated fertilizer per unit time also decreases.

[0027] The rotational speed of the granular fertilizer is preferably within the range of 50 to 2000 revolutions per minute, and more preferably within the range of 100 to 1500 revolutions per minute. If the rotational speed of the granular fertilizer is lower than the above range, the removal of burrs from the granular fertilizer will be insufficient, and the time required for granular fertilizer sizing will increase, resulting in a decrease in the yield of granular fertilizer per unit time. If the rotational speed of the granular fertilizer is higher than the above range, problems such as increased noise and a decrease in the lifespan of the equipment will occur.

[0028] To obtain granular fertilizer with a particle size of a certain size or larger, it is desirable to classify the granular fertilizer using a classifier. There are no particular restrictions on the type of classifier as long as it is capable of dry classification, but it is preferable to use a vibrating sieve. There are no particular restrictions on the mesh size of the sieve as long as it is large enough to obtain the desired particle size, but it is preferable to have mesh sizes of 1.8 to 2.2 mm and 3.8 to 4.2 mm, and it is preferable to use a classification method that combines sieves having these mesh sizes to obtain granular fertilizer with a particle size of 2.0 to 4.0 mm.

[0029] The raw materials are granulated using a compression granulator, the granulated material after compression granulation is crushed using a crusher, dried using a rolling dryer, the granulated material after the hardness has increased is sized using a spherical granulator, and the granular fertilizer after sizing is classified using a classifier. The fine powder obtained after sieving is recycled and mixed into the raw materials and can be used as a raw material.

[0030] <Anti-caking material> After producing granular fertilizer by granulation, crushing, drying, and sizing, the granular fertilizer can be coated with at least one selected from talc, clay, kaolin, bentonite, polyethylene glycol, metal stearate, metal lauryl sulfate, calcium carbonate, silicon dioxide, calcium terephthalate, aluminum oxide, titanium dioxide, calcium phosphate, and lithium fluoride as an anti-caking agent. As for the coating method, if the coating is uniformly applied after granulation and sizing and classification in a classifier, it may be added at the exit of the classifier, mixed and coated using a mixer, or coated by spraying on a belt conveyor.

[0031] The amount of anti-caking agent added to granular fertilizer is preferably 0.05 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of granular fertilizer. To obtain a fertilizer with good solubility and granular hardness without loss due to adhesion to the equipment or affecting the fertilizer component content per unit weight, it is more preferable to add 0.1 parts by weight or more and 0.3 parts by weight or less per 100 parts by weight of granular fertilizer. To further reduce loss due to adhesion to the equipment, it is even more preferable to add 0.15 parts by weight or more and 0.25 parts by weight or less per 100 parts by weight of granular fertilizer.

[0032] The granular fertilizer obtained here can also be used as a bulk blend fertilizer by dry-blending it with other granular fertilizers in any desired ratio. Because this bulk blend fertilizer can be blended in any ratio, it is possible to create a blend that is suitable for each crop.

[0033] <Granulation accelerator> The granulation accelerator is characterized by containing at least one substance selected from an aqueous solution obtained by dissolving at least one substance selected from molasses, starch, carboxymethylcellulose, and lignin sulfonate in water. By adjusting the amount of these substances added, the granular hardness of the granular fertilizer can be controlled, thereby improving the yield. Furthermore, because they have a lubricating effect, they can also be expected to prevent clogging of the powder in the granulation apparatus.

[0034] The amount of the above-mentioned granulation accelerator to be added is determined within the upper limit specified in the list of materials that can be added in Ministry of Agriculture, Forestry and Fisheries Notification No. 2160. If it is carboxymethylcellulose, it is preferable to add 1.0 part by weight or more and 5.0 parts by weight or less per 100 parts by weight of incinerated ash, and to further reduce adhesion loss to the equipment, it is preferable to add 2.0 parts by weight or more and 4.0 parts by weight or less. If it is molasses, starch, or lignin sulfonate, it is preferable to add 10.0 parts by weight or more and 30.0 parts by weight or less per 100 parts by weight of incinerated ash, and to further reduce adhesion loss to the equipment, it is preferable to add 15.0 parts by weight or more and 25.0 parts by weight or less.

[0035] <Nitrogen fertilizer components> The nitrogen fertilizer components used as raw materials in this invention are not particularly limited, and any known nitrogen fertilizer components that are nutrients for plants can be used. Specific examples of nitrogen fertilizer components include ammonium sulfate, ammonium chloride, ammonium nitrate, urea, calcium cyanamide, calcium nitrate, and potassium nitrate. Of these, ammonium sulfate is used, for example, as an aqueous solution of ammonium sulfate obtained by contacting coke oven waste gas with sulfuric acid, or as fine-grained crystalline ammonium sulfate obtained by crystallizing an aqueous solution of ammonium sulfate after obtaining caprolactam and ammonium sulfate by adding ammonia to caprolactam sulfate in the production of caprolactam, and then separating the aqueous caprolactam solution from the aqueous ammonium sulfate solution. Separation of crystals and mother liquor is carried out by known methods. For example, it can be obtained by separating from the liquid by centrifugation and then drying the crystals. If the degree of supersaturation is too high during crystallization, the crystals will rapidly aggregate and incorporate the mother liquor, resulting in large particle size, high moisture content, and many impurities. Therefore, by crystallizing at a pressure of 10.1 kPa ABS or higher, crystal-oriented, highly crystalline fine-grained crystalline ammonium sulfate can be obtained. The degree of crystallinity can be measured by two-dimensional X-ray diffraction, and it is preferable that the degree of orientation determined from the measurement results is 0.995 or higher. More preferably, the degree of orientation is 0.997 or higher, and if the degree of orientation is 1.0, it is the case with the highest crystallinity and is the most preferable. The proportion of fine-grained ammonium sulfate is preferably 30.0% by weight or more, and more preferably 50.0% by weight or more. The degree of orientation is an index indicating the uniformity of the crystals, and is expressed by the following formula (1) from the full width at half maximum (FWHM) of the orientation peak obtained according to the tilt angle χ (°) in two-dimensional X-ray diffraction. Orientation degree = (180 - Orientation peak width at half maximum) / 180 ... (1)

[0036] Furthermore, the particle size of the fine-grained crystalline ammonium sulfate is preferably 1.7 mm or less, as smaller particle sizes, where the crystals do not aggregate and do not incorporate the mother liquor, lead to improved solidification. More preferably, it is 1.4 mm or less, and even more preferably 1.18 mm or less. The particle size of the fine-grained crystalline ammonium sulfate can be determined by classification using a sieve (mesh size 10 = 1.7 mm, 12 mesh = 1.4 mm, 14 mesh = 1.18 mm).

[0037] The ammonia nitrogen content in fine-grained crystalline ammonium sulfate is preferably 20.5% by weight or more, and more preferably 21.0% by weight or more, from the perspective of its fertilizer effect as a nitrogen source per unit weight. The ammonia nitrogen content in fine-grained crystalline ammonium sulfate is the value measured by distillation method (Fertilizer Test Method 4.1.2.a (2021)) in accordance with the official fertilizer analysis method.

[0038] The moisture content of the nitrogen fertilizer component is preferably 5.0% by weight or less. More preferably 4.0% by weight or less, and even more preferably 3.0% by weight or less. When the nitrogen fertilizer component is fine-grained crystalline ammonium sulfate, the moisture content is preferably 0.3% by weight or less. More preferably 0.2% by weight or less, even more preferably 0.1% by weight or less, and most preferably 0.0% by weight, meaning the moisture has been completely dried. The moisture content of the nitrogen fertilizer component is the value measured by the heat loss method (Fertilizer Test Method 3.1.a (2021)) in accordance with the official fertilizer analysis method.

[0039] <Phosphorus fertilizer components> The phosphorus fertilizer components used as raw materials in this invention are not particularly limited, and any known phosphorus fertilizer components that are nutrients for plants can be used. Specific examples of phosphorus fertilizer components include monoammonium phosphate, diammonium phosphate, superphosphate, super superphosphate, and fused phosphate fertilizer. Of these, diammonium phosphate is produced by the neutralization reaction of phosphoric acid and ammonia, and the phosphorus content of diammonium phosphate, calculated on a P2O5 basis, is preferably 46.0% by weight or more, and more preferably 47.0% by weight or more, from the perspective of its fertilizer effect as a phosphorus source per unit weight. Superphosphate is produced by reacting pulverized phosphate rock with sulfuric acid, and the phosphorus content of superphosphate, calculated on a P2O5 basis, is preferably 17.0% by weight or more, and more preferably 18.0% by weight or more, from the perspective of its fertilizer effect as a phosphorus source per unit weight. The phosphorus content of diammonium phosphate and superphosphate, calculated on a P2O5 basis, is the value measured by the ammonium vanadomolybdate spectrophotometric method (Fertilizer Test Method 4.2.1.a (2021)) in accordance with the official fertilizer analysis method. The particle size of the phosphorus fertilizer component is preferably 2.0 mm or less. More preferably 1.4 mm or less, and even more preferably 1.0 mm or less. The particle size and amount of the phosphorus fertilizer component can be determined by classification using a sieve (for example, 9 mesh = 2.0 mm, 12 mesh = 1.4 mm, 16 mesh = 1.0 mm). The moisture content of the phosphorus fertilizer component is preferably 5% by weight or less. More preferably 2.0% by weight or less, and even more preferably 1.0% by weight or less. The moisture content of the phosphorus fertilizer component is the value measured by the heat loss method (Fertilizer Test Method 3.1.a (2021)) in accordance with the official fertilizer analysis method.

[0040] <Potassium fertilizer components> The potassium fertilizer components used as raw materials in this invention are not particularly limited, and any known plant nutrients containing potassium fertilizer components can be used. Specific examples of potassium fertilizer components include potassium sulfate, potassium chloride, and potassium silicate. Of these, potassium chloride is found in potassium chloride minerals such as sylvin and carnalit. Potassium chloride minerals are obtained by excavating potassium veins, a high-purity potassium chloride-containing product is produced at a refining plant, and then it is processed into a powder with an arbitrary particle size distribution using a crusher. The potassium content of potassium chloride in terms of K2O is preferably 60.0% by weight or more, and more preferably 62.0% by weight or more, from the perspective of its fertilizer effect as a potassium source per unit weight. Potassium sulfate is produced by reacting potassium chloride with sulfuric acid. The potassium content of potassium sulfate in terms of K2O is preferably 50.0% by weight or more, and more preferably 52.0% by weight or more, from the perspective of its fertilizer effect as a potassium source per unit weight. The potassium content of potassium chloride and potassium sulfate, converted to K2O, is the value measured by flame atomic absorption spectrometry (Fertilizer Testing Method 4.3.1.a (2021)) in accordance with the official fertilizer analysis method. The particle size of the potassium fertilizer component is preferably 2.0 mm or less. More preferably 1.4 mm or less, and even more preferably 1.0 mm or less. The particle size and amount of the potassium fertilizer component can be determined by classification using a sieve (for example, 9 mesh = 2.0 mm, 12 mesh = 1.4 mm, 16 mesh = 1.0 mm). The moisture content of the potassium fertilizer component is preferably 2.0% by weight or less. More preferably 1.5% by weight or less, and even more preferably 1.0% by weight or less. The moisture content of the potassium fertilizer component is the value measured by the heat loss method (Fertilizer Testing Method 3.1.a (2021)) in accordance with the official fertilizer analysis method. [Examples]

[0041] Examples of the present invention are shown below, but the present invention is not limited to these examples. The method for measuring physical properties, etc., is as follows.

[0042] (1) Potassium concentration Potassium concentration was measured according to the flame atomic absorption spectrometry method described in Fertilizer Testing Method 4.3.1.a (2021).

[0043] (2) Particle size The particle size was determined by using sieves with mesh openings of 2.0 mm and 4.0 mm, and the proportion of particle sizes between 2.0 and 4.0 mm was calculated using the following formula. Particle size (%) of 2.0-4.0 mm = Weight of particles with a particle size of 2.0-4.0 mm / Weight of sieved sample × 100.

[0044] (3) Yield The weight of the granular fertilizer composition obtained by granulation and sizing relative to the weight of the input raw materials was calculated using the following formula. Yield (%) = (Weight of granular fertilizer composition) / (Weight of input raw materials) × 100

[0045] (4) Grain hardness This value was obtained by measuring the granular hardness of 20 individual granules of granular fertilizer using a Kiya-type hardness tester and then calculating the average.

[0046] (5) Moisture content The moisture content of the granular fertilizer composition was determined by the weight loss after drying the granular fertilizer composition at 130°C for 3 hours, and was calculated using the following formula. Moisture content (%) = (Weight of granular fertilizer composition before drying - Weight of granular fertilizer composition after drying) / (Granular fertilizer composition before heating) × 100.

[0047] (Example 1) 97 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 17 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.7% by weight, and it was obtained as a granular fertilizer composition. The granular fertilizer composition was supplied to a Briquetta (registered trademark) BSS-IV type (manufactured by Shinto Industries) as a granulator, and granulation was performed with a roll effective width of 185 mm, a roll pressure of 8.4 kN / cm, a burr thickness of 1.70 mm, a pocket size of 3.9 mm, and a roller rotation speed of 50 rpm to obtain plate-shaped granules. The plate-shaped granules were crushed in a coarse crusher, then fed into a three-stage crushing and sieving machine (manufactured by Kowa Kogyosho) with sieves of 6.7 mm, 5.2 mm, and 2.2 mm mesh sizes. The material was vibrated and crushed using crushing media (200 nylon hard balls in the upper section and 200 in the lower section), and the sieved material was recovered. The sieved material was then supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a temperature of 130°C and a rotation speed of 40 rpm for 20 minutes. Subsequently, it was fed into a marmelizer (manufactured by Dalton) and subjected to sizing treatment at a rotation speed of 225 rpm for 0.5 minutes. After that, it was sent to a circular vibrating sieving machine (manufactured by Dalton) with a sieve of 2.0 mm mesh size for classification, and the sieved material with a 2.0 mm mesh size was recovered as granular fertilizer. As a result, the yield of granular fertilizer was 75.1% by weight, the proportion of particles between 2.0 mm and 4.0 mm was 93.4% by weight, and the particle hardness was 3.2 kgf. In addition, the moisture content of the granular fertilizer was 1.0% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0048] (Example 2) 97 parts by weight of sewage sludge incineration ash with a potassium content of 4.8% by weight, 17 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. The mixture was then supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.7% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 77.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.1% by weight, and the particle hardness was 2.8 kgf. The moisture content of the granular fertilizer was 1.1% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0049] (Example 3) 97 parts by weight of sewage sludge incineration ash with a potassium content of 12.5% ​​by weight, 17 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.2% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 76.3% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 91.1% by weight, and the particle hardness was 2.9 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0050] (Example 4) 97 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 10 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.0% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 72.1% by weight, the proportion of particle size between 2.0 mm and 4.0 mm was 93.1% by weight, and the particle hardness was 2.8 kgf. Furthermore, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0051] (Example 5) 97 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 30 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 3.1% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 74.1% by weight, the proportion of particle size between 2.0 mm and 4.0 mm was 92.2% by weight, and the particle hardness was 2.2 kgf. In addition, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0052] (Example 6) 97 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 8 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.0% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 60.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.2% by weight, and the particle hardness was 1.5 kgf. In addition, the moisture content of the granular fertilizer was 1.3% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0053] (Example 7) 97 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 35 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. The mixture was then supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 3.5% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 44.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.5% by weight, and the particle hardness was 0.8 kgf. The moisture content of the granular fertilizer was 1.4% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0054] (Example 8) 80 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 20 parts by weight of molasses (Nippon Shokuhin Kogyo Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.7% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 80.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 90.5% by weight, and the particle hardness was 4.9 kgf. In addition, the moisture content of the granular fertilizer was 1.0% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0055] (Example 9) 80 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 20 parts by weight of starch (Nishida Starch Factory) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.5% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 77.7% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.4% by weight, and the particle hardness was 2.7 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0056] (Example 10) 80 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 20 parts by weight of lignin sulfonate (Tokyo Chemical Industries Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.5% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 74.9% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 91.4% by weight, and the particle hardness was 2.7 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0057] (Example 11) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.5% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 78.1% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 91.1% by weight, and the particle hardness was 3.2 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0058] (Example 12) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 28 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.3% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 73.6% by weight, the proportion of particle size between 2.0 mm and 4.0 mm was 92.4% by weight, and the particle hardness was 3.2 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0059] (Example 13) 33 parts by weight of sewage sludge incineration ash with a potassium content of 4.8% by weight, 28 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.1% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 80.1% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 90.4% by weight, and the particle hardness was 3.3 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0060] (Example 14) 33 parts by weight of sewage sludge incineration ash with a potassium content of 12.5% ​​by weight, 14 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.7% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 79.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.2% by weight, and the particle hardness was 2.9 kgf. In addition, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0061] (Example 15) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 8 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.1% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 42.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 89.0% by weight, and the particle hardness was 0.9 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0062] (Example 16) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 34 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.9% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 22.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 88.1% by weight, and the particle hardness was 0.5 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0063] (Example 17) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 67 parts by weight of ammonium chloride (Hayashi Pure Chemical Industries Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 3.3% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 77.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 93.3% by weight, and the particle hardness was 3.4 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0064] (Example 18) 33 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 67 parts by weight of urea (Hayashi Pure Chemical Industries, Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.8% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 77.7% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 93.3% by weight, and the particle hardness was 3.2 kgf. In addition, the moisture content of the granular fertilizer was 1.1% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0065] (Example 19) 50 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 50 parts by weight of monoammonium phosphate (Kanto Chemical Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.9% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 70.8% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 91.1% by weight, and the particle hardness was 2.3 kgf. In addition, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0066] (Example 20) 50 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 50 parts by weight of diammonium phosphate (Kanto Chemical Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.2% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 71.1% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 90.8% by weight, and the particle hardness was 2.5 kgf. In addition, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0067] (Example 21) 50 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 14 parts by weight of water, and 50 parts by weight of potassium chloride (Hayashi Pure Chemical Industries Co., Ltd.) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.5% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 73.3% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 93.2% by weight, and the particle hardness was 2.8 kgf. In addition, the moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0068] (Example 22) 31 parts by weight of sewage sludge incineration ash with a potassium content of 2.0% by weight, 16 parts by weight of water, 52 parts by weight of ammonium sulfate (Toray Industries, Inc.), and 17 parts by weight of potassium chloride (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.9% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 77.7% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 93.3% by weight, and the particle hardness was 3.2 kgf. In addition, the moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0069] (Example 23) 31 parts by weight of sewage sludge incineration ash with a potassium content of 4.8% by weight, 16 parts by weight of water, 52 parts by weight of ammonium sulfate (Toray Industries, Inc.), and 17 parts by weight of potassium chloride (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.4% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 78.9% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 92.7% by weight, and the particle hardness was 3.3 kgf. In addition, the moisture content of the granular fertilizer was 1.1% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0070] (Example 24) 31 parts by weight of sewage sludge incineration ash with a potassium content of 12.5% ​​by weight, 16 parts by weight of water, 52 parts by weight of ammonium sulfate (Toray Industries, Inc.), and 17 parts by weight of potassium chloride (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.1% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 79.9% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 94.2% by weight, and the particle hardness was 3.4 kgf. In addition, the moisture content of the granular fertilizer was 0.7% by weight, and no deliquescence during storage, raw material mixing, or generation of toxic gases during granulation was observed.

[0071] (Comparative Example 1) 97 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 17 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. The mixture was then supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.7% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 56.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 91.1% by weight, and the particle hardness was 1.2 kgf. The moisture content of the granular fertilizer was 1.0% by weight and it was hygroscopic during storage. On the other hand, no toxic gas generation was confirmed during raw material mixing or granulation.

[0072] (Comparative Example 2) 97 parts by weight of chicken manure combustion ash with a potassium content of 35.0% by weight, 17 parts by weight of water, and 3 parts by weight of carboxymethylcellulose (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. The mixture was then supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.2% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 52.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 90.3% by weight, and the particle hardness was 1.1 kgf. The moisture content of the granular fertilizer was 0.9% by weight and it was hygroscopic during storage. On the other hand, no toxic gas generation was confirmed during raw material mixing or granulation.

[0073] (Comparative Example 3) 80 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 14 parts by weight of water, and 20 parts by weight of molasses (Nippon Shokuhin Kogyo Co., Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.9% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 45.6% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 78.1% by weight, and the particle hardness was 1.1 kgf. The moisture content of the granular fertilizer was 0.9% by weight and it was hygroscopic during storage. On the other hand, no toxic gas generation was confirmed during raw material mixing or granulation.

[0074] (Comparative Example 4) 80 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 14 parts by weight of water, and 20 parts by weight of starch (Nishida Starch Factory) were put into a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.8% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 49.3% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 77.9% by weight, and the particle hardness was 1.2 kgf. The moisture content of the granular fertilizer was 1.2% by weight and it was hygroscopic during storage. On the other hand, no toxic gas generation was confirmed during raw material mixing or granulation.

[0075] (Comparative Example 5) 80 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 14 parts by weight of water, and 20 parts by weight of lignin sulfonate (Tokyo Chemical Industries Co., Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 3.3% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sizing, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 39.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 80.1% by weight, and the particle hardness was 0.5 kgf. The moisture content of the granular fertilizer was 0.9% by weight and it was hygroscopic during storage. On the other hand, no toxic gas generation was confirmed during raw material mixing or granulation.

[0076] (Comparative Example 6) 33 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 14 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.2% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 38.1% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 90.2% by weight, and the particle hardness was 1.1 kgf. The moisture content of the granular fertilizer was 0.9% by weight, and no deliquescence was observed during storage. On the other hand, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0077] (Comparative Example 7) 33 parts by weight of chicken manure combustion ash with a potassium content of 35.0% by weight, 14 parts by weight of water, and 67 parts by weight of ammonium sulfate (Toray Industries, Inc.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.8% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 43.3% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 89.9% by weight, and the particle hardness was 1.3 kgf. The moisture content of the granular fertilizer was 0.8% by weight, and no deliquescence was observed during storage. On the other hand, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0078] (Comparative Example 8) 33 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 14 parts by weight of water, and 67 parts by weight of urea (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.4% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 40.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 88.2% by weight, and the particle hardness was 1.1 kgf. The moisture content of the granular fertilizer was 1.1% by weight and it was hygroscopic during storage. Furthermore, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0079] (Comparative Example 9) 33 parts by weight of chicken manure combustion ash with a potassium content of 35.0% by weight, 14 parts by weight of water, and 67 parts by weight of urea (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.1% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 45.4% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 87.3% by weight, and the particle hardness was 1.1 kgf. The moisture content of the granular fertilizer was 0.9% by weight and it was hygroscopic during storage. Furthermore, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0080] (Comparative Example 10) 31 parts by weight of chicken manure combustion ash with a potassium content of 20.0% by weight, 16 parts by weight of water, 52 parts by weight of ammonium sulfate (Toray Industries, Inc.), and 17 parts by weight of potassium chloride (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 1.6% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 48.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 87.2% by weight, and the particle hardness was 1.3 kgf. The moisture content of the granular fertilizer was 0.7% by weight, and no deliquescence was observed during storage. On the other hand, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0081] (Comparative Example 11) 31 parts by weight of chicken manure combustion ash with a potassium content of 35.0% by weight, 16 parts by weight of water, 52 parts by weight of ammonium sulfate (Toray Industries, Inc.), and 17 parts by weight of potassium chloride (Hayashi Pure Chemical Industries, Ltd.) were added to a ribbon mixer (manufactured by Sigma Industries) and mixed. Next, the mixture was supplied to a rotary kiln (manufactured by Kurimoto Iron Works) and heated at a heating temperature of 130°C and a rotation speed of 40 rpm for 12 minutes. The moisture content of the dried material was 2.4% by weight, and it was obtained as a granular fertilizer composition. Next, it was granulated, crushed, dried, sized, and classified in the same manner as in Example 1 to recover it as granular fertilizer. As a result, the yield of granular fertilizer was 50.2% by weight, the proportion of particles with a particle size of 2.0 mm or more and 4.0 mm or less was 86.3% by weight, and the particle hardness was 1.3 kgf. The moisture content of the granular fertilizer was 0.7% by weight, and no deliquescence was observed during storage. On the other hand, the generation of ammonia gas during raw material mixing and granulation was confirmed.

[0082] The results of the examples and comparative examples are shown in Tables 1, 2, and 3.

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3] [Industrial applicability]

[0086] The granular fertilizer manufacturing method according to the present invention does not require high-temperature firing or neutralization of raw materials, thus eliminating the need for large-scale equipment and allowing for a simple and efficient manufacturing process to produce granular fertilizer. The granular fertilizer obtained by this invention can be used not only for manual application on small-scale farms but also for mechanical application on large-scale farms. Furthermore, it can be manufactured using raw materials mixed with at least one of the nitrogen, phosphorus, and potassium fertilizer components selected according to the application and purpose, and can also be dry-blended with other granular fertilizers in any ratio to create a bulk blend fertilizer, which can be used for growing rice, vegetables, fruits, etc.

Claims

1. A method for producing a granular fertilizer containing incineration ash having a potassium content of 0.0% by weight or more and 15.0% by weight or less, comprising the following four steps: 1) A step of mixing water with incineration ash having a potassium content of 0.0% by weight or more and 15.0% by weight or less without adding acid. 2) A step of drying the mixture obtained in 1). 3) A step of granulating the dry mixture obtained in 2) into granules. 4) A step of drying the granules obtained in 3)

2. 2. The method for producing a granular fertilizer according to claim 1, further comprising a step of adjusting the shape after step 3) or 4).

3. 2. The method for producing a granular fertilizer according to claim 1, wherein other fertilizer components and / or a granulation promoter are added in step 1).

4. 4. The method for producing a granular fertilizer according to claim 3, wherein the other fertilizer components include at least one fertilizer component selected from the group consisting of a nitrogen fertilizer component, a phosphorus fertilizer component, and a potassium fertilizer component.

5. 5. The method for producing a granular fertilizer according to claim 4, wherein the nitrogen fertilizer component includes at least one selected from the group consisting of ammonium sulfate, ammonium chloride, ammonium nitrate, and urea.

6. 5. The method for producing a granular fertilizer according to claim 4, wherein the phosphorus fertilizer component includes at least one selected from monoammonium phosphate or diammonium phosphate, calcium superphosphate, calcium triple superphosphate, and fused phosphorus fertilizer.

7. 5. The method for producing a granular fertilizer according to claim 4, wherein the potassium fertilizer component includes at least one selected from potassium sulfate, potassium chloride, potassium nitrate, and potassium silicate.

8. 4. The method for producing a granular fertilizer according to claim 3, wherein the granulation promoter is an aqueous solution of at least one selected from the group consisting of molasses, starch, carboxymethyl cellulose, and lignin sulfonate.

9. 9. The method for producing a granular fertilizer according to any one of claims 3 to 8, wherein the amount of water added in step 1) is 10.0% by weight or more and 30.0% by weight or less, based on 100% by weight of the mixture obtained by mixing the incineration ash with other fertilizer components and / or the granulation accelerator.

10. 2) drying the granular fertilizer to a moisture content of 1.0% by weight or more and 10.0% by weight or less in step 2),

11. 2. The method for producing granular fertilizer according to claim 1, wherein the granulation in step 3) is performed by compressing and granulating the raw material using a pair of rollers in a briquetting method.

12. 2. The method for producing a granular fertilizer according to claim 1, wherein in step 4), the granular fertilizer is dried to a moisture content of less than 1.0%.