Granulated material made of by-products, fertilizer and method for producing granulated material

Abstract

To provide a granulated material made of by-products, a fertilizer, and a method for producing the granulated material.SOLUTION: The granulated material 10 contains a granulation target 1, at least a part of which is a by-product, and a binder 2, and the binder 2 contains glycerin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a granule, a fertilizer, and a method for producing the granule using a by-product as a raw material. [Background technology]

[0002] In order to realize a sustainable society, there is a demand for effective use of by-products generated during the manufacturing process of various products.

[0003] As an effective use of by-products, efforts are known to use incineration ash (hereinafter also referred to as biomass ash) discharged from wood biomass power generation as fertilizer, roadbed material, etc. Patent Document 1 describes a method of obtaining fertilizer by mixing acid-impregnated pulverized coal and biomass ash, drying the resulting mixture, adding a binder, and granulating it.

[0004] There are also efforts to make effective use of slag produced in the steelmaking process. Patent Document 2 describes a method for obtaining fertilizer by crushing steelmaking slag produced in the steel manufacturing process to a specified particle size, adding a specified binder, and granulating the slag. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-190642 [Patent Document 2] International Publication No. 2019 / 004339 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Documents 1 and 2, a binder is used to granulate the material to be granulated, such as biomass ash, crushed steel slag, etc. The binder, which is added during granulation, such as blackstrap molasses, lignin, starch, etc., needs to be procured from outside, which leads to an increase in production costs.

[0007] An object of the present invention is to effectively utilize by-products and to more efficiently produce and provide granulated materials. [Means for solving the problem]

[0008] The granulated material according to the present invention is characterized in that it contains a granulated material, at least a part of which is a by-product, and a binder, and the binder contains glycerin.

[0009] Binders are used to promote the aggregation of the granulation materials and improve the strength and surface morphology of the granulation materials. Generally, blackstrap molasses, lignin, starch, etc. are used as binders. These materials have high viscosity, and the viscosity of blackstrap molasses alone is about 26,500 mPa·s. When a solution of these materials dissolved in water is applied to the granulation materials, liquid bridges are formed between the granulation materials, and the granulation materials aggregate due to the interfacial tension between the liquid and solid, forming granules. Then, by evaporating the water contained in the granulation materials, the liquid bridges become solid bridges, and granules with high mechanical strength are obtained. On the other hand, glycerin has a viscosity of about 1,400 mPa·s at 20°C, which is lower than blackstrap molasses, etc., but it can be used as a binder because it forms solid bridges between the granulation materials, at least some of which are by-products. Glycerin is also useful in that it is harmless to the human body and does not undergo thermal decomposition at temperatures below 500°C, making it stable as a compound. Therefore, by-products can be effectively utilized and granulation materials can be produced and provided more efficiently.

[0010] A further characteristic feature of the present invention is that the glycerin contained in the binder is a by-product of biomass fuel production.

[0011] When biomass fuel is produced, glycerin is produced as a by-product. By using this by-product glycerin as a binder, it becomes possible to procure raw materials at low cost, which reduces the manufacturing cost of granulated materials. In addition, the by-product glycerin can be effectively utilized.

[0012] A further characteristic feature of the present invention is that the by-product includes at least one of steelmaking slag and biomass ash.

[0013] Biomass ash is a by-product of wood biomass power generation, and steelmaking slag is a by-product generated during the steel manufacturing process. By using these by-products as granulation targets, they can be effectively utilized without being discarded.

[0014] A further characteristic feature of the present invention is that the granulation object is carbonated by contacting the by-product with a fluid containing carbon dioxide.

[0015] The biomass ash to be granulated is incineration ash discharged from wood biomass power generation, etc., and although it is used in some places as a soil conditioner or fertilizer, it is often disposed of as industrial waste because it contains heavy metals, etc. In this configuration, such biomass ash is carbonated to suppress the elution of heavy metals, and then granulated with glycerin, making it possible to effectively use even biomass ash containing heavy metals, etc. as a soil conditioner or fertilizer. In addition, carbonation can also fix carbon dioxide as calcium carbonate.

[0016] In addition, steel slag, which is the material to be granulated, may contain unreacted lime, and if CaO remains in the granulated material produced using these as raw materials, there is a problem that the granulated material expands due to slaking, etc., and the quality of the granulated material is unstable. Therefore, by performing a carbonation treatment before granulation, the content of unreacted lime can be reduced, making it possible to obtain granulated material with stable quality. Furthermore, since CaO is easily dissolved in glycerin, glycerin is not suitable as a binder for granulation of granulated materials with a high CaO content. However, by performing a carbonation treatment in advance to reduce the CaO content of the granulated material, it becomes possible to granulate the granulated material with a high CaO content using glycerin.

[0017] The fertilizer according to the present invention is characterized in that it contains the granules.

[0018] Plants require many elements, including nitrogen, phosphorus, and potassium, to grow. Biomass ash contains potassium, calcium, silicon, etc., so granulated material made from this can be used as fertilizer to supply the elements necessary for plant growth. Similarly, slag contains elements such as phosphorus, iron, manganese, silicon, calcium, magnesium, boron, and sulfur, so granulated material made from this can be used as fertilizer. Furthermore, granulated material made from glycerin as a binder has low strength and good disintegration properties compared to granulated material made from other binders, making it suitable as a fertilizer.

[0019] A further characteristic feature of the present invention is that it includes a granulation step of granulating a material to be granulated that has by-products by using a binder containing glycerin.

[0020] Glycerin has a viscosity of approximately 1400 mPa·s at 20℃, so it can crosslink and aggregate the materials to be granulated. Therefore, glycerin can be used as a binder instead of existing binders.

[0021] A further characteristic feature of the present invention is that the glycerin contained in the binder is a by-product of biomass fuel production.

[0022] When biofuel is produced, glycerin is produced as a by-product. By using this by-product glycerin as a binder, it becomes possible to procure raw materials at low cost, thereby reducing the manufacturing cost of granulated materials.

[0023] A further characteristic feature of the present invention is that the by-product includes at least one of steelmaking slag or biomass ash.

[0024] Biomass ash is a by-product of wood biomass power generation, and steelmaking slag is a by-product generated during the steel manufacturing process. By using these by-products as granulation materials, they can be effectively utilized without being discarded.

[0025] A further characteristic feature of the present invention is that a carbonation treatment step is carried out before the granulation step, in which carbonation is carried out by bringing the by-product into contact with a fluid containing carbon dioxide.

[0026] Biomass ash is incineration ash discharged from wood biomass power generation, and although it is used in some places as a soil modifier or fertilizer, it is often disposed of as industrial waste because it contains heavy metals, etc. In the present invention, such biomass ash is carbonized to suppress the elution of heavy metals, and then granulated with glycerin, making it possible to effectively use even biomass ash containing heavy metals, etc. as a soil modifier or fertilizer. In addition, carbonation can also fix carbon dioxide as calcium carbonate.

[0027] Steelmaking slag may contain unreacted lime, and if CaO remains in the granulated material produced using these as raw materials, there is a problem that the granulated material expands due to slaking, etc., resulting in unstable quality. Therefore, by performing a carbonation treatment before granulation, the content of unreacted lime can be reduced, making it possible to obtain granulated material with stable quality. In addition, since CaO is easily dissolved in glycerin, glycerin is not suitable as a binder for granulation of granulated materials with a high CaO content. However, by performing a carbonation treatment in advance to reduce the CaO content of the granulated material, it becomes possible to granulate the granulated material with a high CaO content using glycerin. [Brief description of the drawings]

[0028] [Figure 1] FIG. 2 is a process block diagram of a method for producing a granulated material according to the first embodiment. [Diagram 2]FIG. 4 is a process block diagram of a method for producing a granulated material according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the granulated material made from a by-product according to the present invention will be described with reference to the drawings. In this embodiment, as an example of the granulated material made from a by-product, a granulated material made from biomass ash or steel slag will be described. However, the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the present invention.

[0030] First Embodiment Fig. 1 is a process block diagram of a method for producing a granulated material according to the first embodiment. A granulated material 10 according to the first embodiment is obtained by adding a binder aqueous solution 2 in which a binder containing glycerin is dissolved in water to a granulation target material 1, which is a by-product in a granulation step 3, and granulating the resultant.

[0031] The granulation object 1 can be biomass ash. Biomass ash is incineration ash discharged from power generation using unused thinning wood, which is woody biomass, and contains elements useful for fertilizers, such as potassium, calcium, and silicon. The granulation object 1 is not limited to biomass ash, and blast furnace slag, steelmaking slag, steelmaking dust, and the like generated in the steelmaking process can also be used. Since steelmaking slag contains unreacted lime (CaO), it may be treated to reduce CaO before granulation. By carrying out such treatment, it is possible to suppress the expansion of the slag due to the digestion of CaO. Slag, etc., can be crushed to become the granulation object 1 suitable for granulation. The granulation object 1 is not limited to these, and any composition can be used as long as it is intended for granulation.

[0032] The binder aqueous solution 2 is obtained by adding water to glycerin, which is a binding agent. The viscosity of glycerin is about 1400 mPa·s at 20°C, which is lower than that of blackstrap molasses, which is a conventionally used binding agent, but it can sufficiently crosslink the granulation objects 1. The glycerin may be commercially available, or may be obtained as a by-product during the production of bioethanol or biodiesel fuel, which are biomass fuels. Biodiesel fuel is obtained by reacting waste oil with methanol, and high-purity glycerin can be obtained by using a solid catalyst (metal oxide or enzyme) as the catalyst. Among them, glycerin produced using an enzymatic method (CoolProcess (CP) (registered trademark)) is of high quality, so it is preferable to use glycerin produced using these catalysts.

[0033] In this embodiment, 1 to 20% by weight of glycerin can be added to the total amount of the granulation target material 1. The greater the amount of glycerin added, the easier it is for crosslinks to form between the granulation target materials 1, and the strength of the granulation target material 10 is improved. On the other hand, since a good granulation target material 10 can be obtained even when the amount of glycerin added is 10% by weight or less, it is more preferable that the amount of glycerin added is 1 to 10% by weight. Furthermore, in addition to glycerin, an existing binder such as blackstrap molasses or lignin sulfonic acid may be mixed and used.

[0034] In this embodiment, 5 to 40% by weight of water is added to glycerin relative to the total amount of the granulation object 1 to prepare the binder aqueous solution 2. The addition of water dilutes glycerin, reducing the viscosity, which makes it easier for glycerin to adhere uniformly to the surface of the granulation object 1 and makes it easier to form a large number of bridges between the granulation objects 1. In addition, since it is possible to spray the binder aqueous solution 2 using a nozzle or the like, it is possible to uniformly add the binder aqueous solution 2 to the granulation object 1. The more water is added, the shorter the granulation time can be, but the strength of the granulation object 10 tends to decrease. On the other hand, the less water is added, the higher the strength of the granulation object 10 is, but the granulation time tends to increase. Therefore, the amount of water added is preferably 10 to 30% by weight. The water used is not limited to clean water, and may be industrial water or factory wastewater.

[0035] In the granulation step 3, various granulation methods such as rolling granulation, stirring granulation, and extrusion granulation can be used. In rolling granulation, the binder aqueous solution 2 is sprayed onto the granulation target 1, and the granulation target 1 is rotated along with the rotation of the granulation vessel, thereby obtaining a granulated product 10 in which the granulation target 1 is aggregated by the binder aqueous solution 2. In stirring granulation, the granulation target 1 and the binder aqueous solution 2 are stirred and mixed to aggregate and granulate the granulation target 1, thereby obtaining a granulated product 10. In extrusion granulation, the binder aqueous solution 2 is added to the granulation target 1, mixed, and then extrusion molding is performed to obtain a granulated product 10. In either method, a known granulation device can be used.

[0036] The granulated material 10 obtained in the granulation step 3 is formed by agglomeration of the granulation objects 1 by liquid bridging with the binder aqueous solution 2, and therefore, by drying, the moisture is evaporated and the granulation objects 1 can be cross-linked with each other only by glycerin. Therefore, by drying, it is possible to increase the mechanical strength of the granulated material 10. The drying of the granulated material 10 can be performed by any device capable of drying the granulated material 10, for example, a heating furnace or a rotary kiln. Furthermore, drying is not limited to heating, and moisture may be evaporated by curing in the air or the like.

[0037] The granulated material 10 can be used as a fertilizer, a soil conditioner, or a roadbed material. When used as a fertilizer, the particle size of the granulated material 10 is preferably 1.0 to 5.0 mm, more preferably 2.0 to 4.0 mm. When used as a roadbed material or the like, the particle size is preferably 60 mm or less. The particle size can be adjusted by the granulation time, the amount of binder solution 2 added, and the granulation device used, so that the granulated material 10 having the desired particle size can be manufactured according to the intended use.

[0038] Second Embodiment 2 is a process block diagram of a method for producing a granulated material according to the second embodiment. The granulated material 1 according to the second embodiment undergoes a carbonation treatment process 4, and then is mixed with an aqueous binder solution 2 containing glycerin in a granulation process 3 and granulated to become a granulated material 10. The other configurations are the same as those in the first embodiment, so detailed explanations of the same configurations as those in the first embodiment will be omitted.

[0039] Biomass ash, which is the granulation object 1, may contain heavy metals such as lead and cadmium. Since biomass ash also contains Ca components, calcium carbonate can be produced by contacting the biomass ash with a gas or fluid containing carbon dioxide. By using a heavy metal immobilizing agent in such a carbonation process, it is possible to prevent the heavy metals from eluting. Therefore, even if a granulation object 1 containing heavy metals is used, a granulation object 10 that is not harmful to the environment can be obtained by performing the carbonation process. Furthermore, since carbon dioxide can be fixed as calcium carbonate by performing the carbonation process, it is possible to reduce the amount of carbon dioxide emissions by, for example, absorbing carbon dioxide contained in exhaust gas into the granulation object 1.

[0040] In addition, the steel slag, which is the granulation target 1, may contain unreacted CaO. CaO is easily dissolved in the glycerin contained in the binder aqueous solution 2, so if the granulation target 1 contains a large amount of CaO, the glycerin will no longer function as a binder. Therefore, in order to perform good granulation, it is preferable to perform a carbonation treatment to reduce the CaO content in the granulation target 1. The carbonation treatment is performed by contacting the granulation target 1 with a gas or liquid containing carbon dioxide. In addition, when treating the CaO contained in the steelmaking slag, the Ca component may be extracted from the steelmaking slag using a solvent made of a mixture of glycerin and water. The steelmaking slag from which the Ca component has been extracted may be mixed with biomass ash and then carbonation treatment may be performed again.

[0041] Next, a method for producing a granulated material 10 according to the first embodiment will be described with reference to FIG.

[0042] First, the material to be granulated 1 is placed in a granulator. The granulator may be a rotating pan type granulator, a rotating drum granulator, an agitating fluidized bed granulator, a screw extrusion type granulator, or the like. In this embodiment, a rotating pan type granulator is used, and the material to be granulated 1 is placed in a container rotating at a low speed.

[0043] Next, the binder aqueous solution 2 containing glycerin is sprayed in a mist form to adhere to the surface of the granulation object 1. As the granulation object 1 rolls along with the rotation of the container, the granulation object 1 collides with each other, and the binder aqueous solution 2 forms a liquid bridge between the granulation object 1 to obtain the granulation object 10. The granulation object 10, which has become particles of a predetermined size, is discharged outside the container, and when the moisture is removed by drying, it develops mechanical strength. Drying can be performed by curing or by heating with a device such as a heating furnace or a rotary kiln. In addition, as a pretreatment of the granulation object 1, the granulation object 1 may be crushed before the granulation step 3 to obtain a particle size suitable for granulation.

[0044] Next, a method for producing the granulated material 10 according to the second embodiment will be described with reference to FIG.

[0045] First, the carbonation process 4 is performed on the granulation target 1. The carbonation process can be performed by a known method, and the Ca component contained in the granulation target 1 is converted to calcium carbonate by contacting the granulation target 1 with a gas or liquid containing carbon dioxide. This makes it possible to prevent the elution of heavy metals. Therefore, whether or not the carbonation process 4 can be performed may be determined by measuring the concentration of heavy metals contained in the granulation target 1. In addition, since carbon dioxide can be fixed by performing the carbonation process, it becomes possible to effectively utilize carbon dioxide contained in, for example, exhaust gas. Furthermore, when CaO is contained in the granulation target 1, the carbonation process can prevent CaO from dissolving in glycerin, so that granulation can be performed reliably.

[0046] The material 1 to be granulated is then placed in a slowly rotating container, and a mist of an aqueous binder solution 2 containing glycerin is sprayed onto the material 1 to adhere the aqueous binder solution 2 to the surface of the material 1. As the material 1 rolls along with the rotation of the container, collisions between the material 1 occur, causing the aqueous binder solution 2 to form liquid bridges between the material 1 to produce granulated material 10. The granulated material 10, which has become particles of a specified size, is discharged outside the container, and mechanical strength is developed when the moisture is removed by drying.

[0047] [Example] An example of the granulated material 10 is described below.

[0048] Steelmaking slag and biomass ash were selected as the granulation object 1. In the examples, only steelmaking slag or a mixture of steelmaking slag and biomass ash in a weight ratio of 4:1 was used, and carbonation treatment was performed if applicable, and the granulation object 10 was prepared by mixing with the binder aqueous solution 2 in a granulation device and granulating (Examples 1 to 4). The carbonation treatment was performed by adding a predetermined amount of water to the granulation object 1, mixing, and then contacting the granulation object 1 with carbon dioxide gas. Only in Example 4, steelmaking slag that had been subjected to Ca extraction treatment was used. Commercially available glycerin was used, and the binder aqueous solution 2 was prepared using pure water. In the examples, the amount of glycerin added and the amount of water added were adjusted so that the concentration of the binder aqueous solution 2 was constant. Table 1 shows the presence or absence of carbonation treatment, the amount of glycerin added and the amount of water added, the concentration of the binder aqueous solution 2, and the average strength of the granulation object 10. The average strength was measured using granulated material 10 having a particle size of 2.0 to 2.8 mm by a crushing test specified in JIS Z 8841. As a comparative example, magnesium lignin sulfonate was used as a binder to granulate steel slag (comparative example).

[0049] [Table 1]

[0050] Since the granulated material 10 was obtained satisfactorily in all of Examples 1 to 4, it was found that glycerin can be effectively used as a binder. In addition, from Table 1, it was found that the average strength of Examples 1 to 4 was less than half that of the comparative example, and all of them were low in strength. From a comparison between Example 1 and Example 2, it was found that the strength tended to increase as the amount of glycerin used increased. Furthermore, the strength of Examples 3 and 4, in which steelmaking slag and biomass ash were blended, was lower than the strength of Example 2, in which only steelmaking slag was used, and it was found that the strength of the granulated material 10 decreased by blending biomass ash. Since the lower the strength, the better the disintegration property tends to be, it is expected that the granulated material 10 using glycerin as a binder is useful as a fertilizer.

[0051] Next, in Example 4, steelmaking slag and biomass ash were mixed in a weight ratio of 4:1 and granulated with glycerin to measure the citrate-soluble phosphoric acid, citrate-soluble potassium, water-soluble potassium, soluble silicic acid, and alkali content (Example 5). These measurements were performed based on the Testing Methods for Fertilizers, etc. (2022). Similar measurements were also performed on the powder of steelmaking slag (Example 6) that was subjected to a Ca extraction process and then a carbonation process, which is the granulation target 1, and the powder of biomass ash that was subjected to a carbonation process (Example 7).

[0052] [Table 2]

[0053] Table 2 shows the measured values ​​of each component in Examples 4 to 6. Example 5 has a high content of citric acid-soluble phosphoric acid, soluble silicic acid, and alkali, and meets the standard values ​​for by-product lime fertilizer, by-product fertilizer, and slag phosphate fertilizer. Example 6 has a high content of citric acid-soluble potassium and water-soluble potassium, and meets the standard for by-product fertilizer. Example 4 is a blend of Example 5, which can be used as a phosphate fertilizer or silicic acid fertilizer, and Example 6, which can be used as a potassium fertilizer, and has a high content of citric acid-soluble phosphoric acid, citric acid-soluble potassium, and alkali. Therefore, it was found that Example 4 meets the standard for chemical fertilizers.

[0054] In particular, the main component of Example 4 meets the standard value for mineral silicate fertilizers, and has an average strength of 11.5 N / mm 2 In comparison, the average strength of the granules 10 in Example 4 is 2.1 N / mm 2 Therefore, it was found that the granulated material 10, which is made by adding glycerin as a binder to the granulated material 1 made from by-product steelmaking slag and biomass ash, can be expected to have good disintegration properties and is useful as a fertilizer.

[0055] Other embodiments (1) In this embodiment, steelmaking slag or a mixture of steelmaking slag and biomass ash was used as the granulation object 1, but biomass ash alone may be used as the granulation object 1. In addition, the compounding ratio of the granulation object 1 is not limited to that described in the embodiment.

[0056] (2) In the above embodiment, a polyol compound may be used as a binder in addition to a small amount of glycerin. As long as the binder has a viscosity equivalent to that of glycerin, the granulated material 10 can be produced. [Industrial Applicability]

[0057] The present invention can be used for granulated materials made from by-products. [Explanation of symbols]

[0058] 1: material to be granulated, 2: aqueous binder solution (binding agent), 3: granulation process, 4: carbonation process, 10: granulated material

Claims

1. A granulated product comprising a granulation target material, at least a portion of which is a by-product, and a binder, The binder is a granule containing glycerin.

2. The granulated material according to claim 1 , wherein the glycerin contained in the binder is a by-product during biomass fuel production.

3. The granulated material according to claim 2 , wherein the by-product comprises at least one of steelmaking slag and biomass ash.

4. The granulated material according to claim 3, wherein the granulated material is carbonated by contacting the by-product with a fluid containing carbon dioxide.

5. A fertilizer comprising the granules according to any one of claims 2 to 4.

6. A method for producing a granulated material, comprising a granulation step of granulating a granulation target having a by-product using a binder containing glycerin.

7. The method for producing granulated material according to claim 6, wherein the glycerin contained in the binder is a by-product during biomass fuel production.

8. The method for producing granulated material according to claim 7 , wherein the by-product contains at least one of steelmaking slag and biomass ash.

9. The method for producing a granulated product according to claim 8, further comprising carrying out a carbonation treatment step prior to the granulation step, in which the by-product is brought into contact with a fluid containing carbon dioxide to effect carbonation.

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