Basicity adjusting agent, method for producing the same, and waste melting treatment method

Abstract

To provide a basicity adjusting agent that can be effectively used for adjusting basicity even if the size of a lime source or a silica source is fine.SOLUTION: A basicity adjusting agent comprises a molded body containing an inorganic substance containing at least one of a lime source and a silica source, plastic, and biomass. The content of the plastic with respect to the entire molded body is 20 mass% or more to less than 50 mass%, and the content of the biomass in the entire molded body is 20 mass% or more.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] One aspect of this disclosure relates to basicity adjusting agents and methods for producing the same, as well as methods for melting waste. [Background technology]

[0002] As a method of waste disposal, a waste melting treatment method is known, in which waste is melted using a melting furnace. In such a treatment method, molten slag is discharged from the melting furnace. If the SiO2 component in the molten slag is excessive, its viscosity increases, making it difficult to discharge from the melting furnace. For this reason, a technique is known to adjust the basicity of the molten slag by supplying a lime source.

[0003] For example, Patent Document 1 proposes that when using seashells mainly composed of CaCO3 as a lime source for adjusting the basicity of molten slag, the particle size should be within a predetermined range when charging them into a melting furnace. This attempts to suppress the scattering of seashells from the melting furnace and the residue of free CaO in the slag, thereby effectively utilizing the seashells as a basicity adjusting agent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-216243 [Overview of the project] [Problems that the invention aims to solve]

[0005] Introducing a lime or silica source used in a basicity adjusting agent into a melting furnace after adjusting its size to a predetermined range has the advantage of effectively utilizing the lime or silica source as a basicity adjusting agent. However, in this case, lime and silica sources with a size below the lower limit cannot be used as a basicity adjusting agent. Therefore, we provide a basicity adjusting agent and a method for producing the same that can effectively utilize lime or silica sources even if their size is very fine. We also provide a waste melting treatment method that can effectively utilize lime or silica sources even if their size is very fine. [Means for solving the problem]

[0006] (1) One aspect of the present disclosure provides a basicity adjuster comprising a molded article containing an inorganic material including at least one of a lime source and a silica source, a plastic, and biomass, wherein the plastic content of the molded article is 20% by mass or more and less than 50% by mass, and the biomass content of the molded article is 20% by mass or more.

[0007] The basicity adjusting agent described above includes a molded body containing inorganic material, at least one of a lime source and a silica source. When this molded body is introduced into a melting furnace or the like, it is gradually heated. In the temperature range of approximately 400°C or less, the plastic contained in the molded body softens or melts and functions as a binder. This maintains the shape of the molded body. Above 400°C, the plastic decomposes, and components such as lignin contained in the biomass function as a binder. This maintains the shape of the molded body. Since the molded body contains a predetermined amount of plastic and biomass, it can maintain its shape from room temperature to high temperatures. Therefore, even if at least one of the lime source and silica source contained in the molded body is fine, it is retained within the molded body, thus suppressing scattering from the melting furnace or the like. Accordingly, a basicity adjusting agent containing such a molded body can be effectively used to adjust basicity even if the lime source or silica source is fine.

[0008] (2) In (1) above, the inorganic material includes a lime source, and the lime source content relative to the entire molded body may be 10 to 60% by mass. In a melting furnace, a large amount of lime source is used to adjust the basicity of the molten slag, so a molded body containing a certain amount of lime source along with plastic and biomass is particularly useful as a basicity adjuster for a melting furnace.

[0009] (3) In the basicity adjusting agent of (1) or (2) above, the inorganic material contains particles having a particle size of 1 mm or less, and the particle size of the molded body may be 5 to 100 mm. Of the inorganic material, particles having a particle size of 1 mm or less may scatter in the melting furnace. However, the inorganic material in the basicity adjusting agent is contained in a molded body having a particle size of a predetermined size. Therefore, the scattering of inorganic material containing particles having a particle size of 1 mm or less in the melting furnace can be sufficiently suppressed. Furthermore, if the molded body is of the above size, the plastic and biomass will decompose and disappear when heated, so the basicity adjusting function of the molten slag can be fully exercised.

[0010] (4) In any one of the basicity adjusting agents described in (1) to (3) above, the plastic may include thermoplastic plastic, and the biomass may include woody biomass. Thermoplastic plastics can melt at temperatures of approximately 400°C or lower and fully function as a binder. Woody biomass has a high lignin content and can fully function as a binder even in temperature environments exceeding 400°C. Therefore, molded articles containing thermoplastic plastic and woody biomass can maintain sufficiently high strength when heated.

[0011] (5) In any one of the basicity adjusting agents described in (1) to (4) above, the density of the molded body is 0.95 g / cm³. 3 The above is sufficient. Since such molded bodies have excellent shape retention, even if the lime source or silica source is fine, the scattering of inorganic matter can be sufficiently suppressed.

[0012] (6) One aspect of the present disclosure provides a method for producing a basicity adjuster including a molded body, comprising the step of producing a molded body by pressurizing a raw material containing an inorganic material including at least one of a lime source and a silica source, a plastic, and biomass while heated to 140 to 350°C, wherein the plastic content relative to the total raw material is 20% by mass or more and less than 50% by mass, and the biomass content relative to the total raw material is 20% by mass or more.

[0013] The basicity adjusting agent described above includes a molded body produced by pressurizing a raw material containing inorganic substances, including at least one of a lime source and a silica source, while heated to 140-350°C. When such a molded body is introduced into a melting furnace, it is gradually heated. In the temperature range of approximately 400°C or below, the plastic contained in the molded body softens or melts and functions as a binder. This maintains the shape of the molded body. Above 400°C, the plastic decomposes, and components such as lignin contained in the biomass function as a binder. This maintains the shape of the molded body. Since the molded body contains a predetermined amount of plastic and biomass, it can maintain its shape from room temperature to high temperatures. Therefore, even if at least one of the lime source and silica source contained in the molded body is fine, it is retained within the molded body, thus suppressing scattering from the melting furnace. Consequently, even if the lime source or silica source is fine, it can be effectively used for adjusting the basicity.

[0014] (7) One aspect of the present disclosure is a waste melting treatment method for which waste is charged into a melting furnace and melted, wherein the auxiliary material is a step of adjusting the basicity of the molten slag using one of the basicity adjusting agents described in (1) to (5) above.

[0015] In the above waste treatment method, any one of the above-mentioned (1) to (5) basicity adjusters is used for adjusting the basicity. This basicity adjuster includes a molded body containing an inorganic substance containing at least one of a lime source and a silica source. When this molded body is introduced into a melting furnace, it is gradually heated. In a temperature range of generally 400°C or lower, the plastic contained in the molded body softens or melts and functions as a binder. Thereby, the shape of the molded body is maintained. When the temperature exceeds 400°C, the plastic decomposes, and components such as lignin contained in the biomass function as a binder. Thereby, the shape of the molded body is maintained. Since the molded body contains a predetermined amount of plastic and biomass, it can maintain its shape from room temperature to a high temperature range. Therefore, even if at least one of the lime source and the silica source contained in the molded body is fine, it is retained in the molded body, so that scattering from the melting furnace is suppressed. Therefore, a fine lime source or silica source can be effectively used for adjusting the basicity.

Advantages of the Invention

[0016] It is possible to provide a basicity adjuster and a method for producing the same that can be effectively used for adjusting the basicity even if the size of the lime source or silica source is fine. Further, it is possible to provide a waste melting treatment method that can be effectively used for adjusting the basicity even if the size of the lime source or silica source is fine.

Brief Description of the Drawings

[0017] [Figure 1] It is a flowchart of a method for producing a basicity adjuster. [Figure 2] It is a diagram schematically showing an example of a melting furnace and waste melting treatment equipment including the same. [Figure 3] It is a schematic diagram of a measuring device used for measuring the crushing strength of a molded body. [Figure 4] It is a graph showing the relationship between the content rate of plastic (PP) in a molded body and the crushing strength. [Figure 5] It is a graph showing the relationship between the molding pressure and the density of a molded body. [Figure 6] (A) is a photograph showing the appearance of the molded body before carbonization, and (B) is a photograph showing the appearance of the molded body after carbonization.

Embodiments for Carrying out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as appropriate. However, the following embodiments are examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content.

[0019] The basicity adjuster according to one embodiment is composed of a molded body containing at least one of a lime source and a silica source, an inorganic substance, a plastic, and biomass. The lime source in this specification includes CaO and substances containing the same, as well as substances that produce CaO when heated. Examples of the lime source include calcium carbonate, calcium hydrogen carbonate, quicklime (calcium oxide), slaked lime (calcium hydroxide), limestone, steel slag, dolomite, cement, and fly ash. From the viewpoint of improving handling properties and safety, the lime source does not have to contain quicklime.

[0020] The silica source in this specification includes substances containing SiO2 or silicate. Examples of the silica source include steel slag, silica sand, cement, and fly ash. Note that substances containing both SiO2 or silicate and CaO or substances that produce CaO when heated correspond to both the lime source and the silica source. Substances corresponding to both the lime source and the silica source can be either the lime source or the silica source. The inorganic substance in this specification may contain one or more substances corresponding to both the lime source and the silica source, or may contain one or more substances corresponding to only one of the lime source and the silica source.

[0021] The basicity of molten slag can be adjusted by including inorganic materials in the molded body that constitutes the basicity adjusting agent. The mass ratio of CaO / SiO2 in the inorganic material may be 0.5 or less or 2 or more, or 0.3 or less or 2.5 or more, from the viewpoint of fully exhibiting the basicity adjusting function of the molten slag. The masses of CaO and SiO2 mentioned above are determined by converting the Ca and Si components contained in the inorganic material to CaO and SiO2 equivalents.

[0022] From the viewpoint of ensuring a sufficiently high basicity adjustment function of the basicity adjusting agent, the inorganic content of the entire molded body may be 5% by mass or more, 10% by mass or more, 20% by mass or more, or 25% by mass or more. From the viewpoint of ensuring sufficiently high shape retention of the molded body constituting the basicity adjusting agent from room temperature to high temperatures, the inorganic content of the entire molded body may be 60% by mass or less, 55% by mass or less, or 50% by mass or less. From the viewpoint of maintaining both basicity adjustment function and shape retention at a high level, the inorganic content of the entire molded body may be 5 to 60% by mass.

[0023] The lime source content in the entire molded body may be 10-60% by mass, 20-50% by mass, or 25-45% by mass. In melting furnaces (waste melting furnaces), CaO is often required more than SiO2 to adjust the basicity of the molten slag. For this reason, molded bodies containing a lime source are particularly useful as basicity adjusters for melting furnaces. This lime source may also contain SiO2 or silicates in addition to CaO or a substance that produces CaO when heated. From the viewpoint of sufficiently increasing the basicity adjustment function of the molten slag, the CaO / SiO2 mass ratio in the lime source may be 1 or more, 3 or more, or 5 or more. The respective masses of CaO and SiO2 mentioned above are determined by converting the Ca and Si components contained in the lime source to CaO and SiO2.

[0024] The plastic may be a thermoplastic, a thermosetting plastic, or a combination thereof. From the viewpoint of shape retention at around 300-400°C, the plastic may include a thermoplastic. From the viewpoint of reducing manufacturing costs, waste plastic may be used as the plastic source. Examples of plastics include polyethylene, polyolefins such as polypropylene, polystyrene, acrylonitrile styrene resin, ABS resin, polyvinyl chloride, acrylic resin, methacrylic resin, PET resin, PVA resin, polyvinylidene chloride, polyvinylidene fluoride, and phenolic resin.

[0025] Plastics generally have the function of maintaining the shape of a molded article in a temperature range of 400°C or less. If the plastic content is excessive, the number of voids created by the decomposition of the plastic increases. From the viewpoint of maintaining good shape retention of the molded article in the temperature range of 400°C or less and in the temperature range of 400°C or more, the plastic content of the total molded article should be 20% by mass or more and less than 50% by mass. From the viewpoint of further improving shape retention in the temperature range of 400°C or less, the plastic content of the total molded article may be 25% by mass or more and may be 30% by mass or more. From the viewpoint of further improving shape retention in the temperature range of 400°C or more, the plastic content of the total molded article may be 45% by mass or less and may be 40% by mass or less.

[0026] Biomass includes woody biomass and herbaceous biomass. Woody biomass may include not only trees, but also construction waste, forest residues, bark and sawdust generated from sawmills, branches and leaves generated during tree felling and street tree pruning. Herbaceous biomass includes grasses, as well as agricultural by-products such as rice straw, rice husks, and wheat straw. Of the above biomass, biomass containing lignin exhibits superior binder function at high temperatures. Among the components contained in biomass, hemicellulose decomposes at 200-300°C, and cellulose at 300-400°C. In contrast, lignin has a thermal decomposition temperature of 200-900°C, which is higher than that of other components. From this perspective, biomass may include woody biomass with a high lignin content. The lignin content in biomass may be, for example, 15-35% by mass.

[0027] Biomass has the function of maintaining the shape of the molded body after the plastic has been thermally decomposed at temperatures exceeding 400°C. From the viewpoint of maintaining good shape retention of the molded body in this temperature range, the biomass content relative to the total molded body is 20% by mass or more. From the viewpoint of further improving the shape retention of the molded body in this temperature range, the biomass content relative to the total molded body may be 25% by mass or more, or even 30% by mass or more.

[0028] As the biomass content increases, the plastic and inorganic content decreases. From the viewpoint of maintaining high shape retention of the molded body in the temperature range above 400°C, while improving the shape retention and basicity adjustment function of the molded body in the temperature range below 400°C, the biomass content of the total molded body may be 75% by mass or less, 70% by mass or less, or 60% by mass or less.

[0029] The inorganic material may contain particles having a particle size of 1 mm or less, 0.6 mm or less, or 0.4 mm or less. If the inorganic material contains a lime source, the lime source may contain particles having a particle size of 1 mm or less, 0.6 mm or less, or 0.4 mm or less. If the inorganic material contains a silica source, the silica source may contain particles having a particle size of 1 mm or less, 0.6 mm or less, or 0.4 mm or less. Particles with such small particle sizes have excellent reactivity. Therefore, the basicity adjustment function of the molten slag can be further enhanced. There is no particular limit to the lower limit of the particle size of the above particles contained in the inorganic material, lime source, and silica source; for example, it may be 0.01 mm.

[0030] The biomass may be in the form of chips (wood chips). The particle size of such wood chips may be 60 mm or less, 1 to 50 mm, or 3 to 40 mm. The plastic may be in the form of granules or lumps. The particle size of such granular or lumpy plastic may be 60 mm or less, 1 to 50 mm, or 3 to 40 mm.

[0031] In this specification, the particle size of inorganic materials, lime sources, silicon sources, biomass (wood chips), and plastics (plastic chunks or plastic granules) is measured as the diameter of the circumscribed circle that circumscribes each two-dimensional image of the respective particle (chip or chunk). If the diameter of the circumscribed circle differs depending on the orientation when the particle (chip or chunk) is imaged, the maximum diameter shall be taken as the particle size of the particle (chip or chunk).

[0032] The shape of the molded body contained in the basicity adjusting agent is not particularly limited, and various shapes such as cylindrical, spherical, rectangular prism, and Masek shape can be used. The particle size of the molded body contained in the basicity adjusting agent may be 5 to 100 mm. This allows the basicity adjusting function to be fully exercised while sufficiently reducing the amount of scattering when charged into the melting furnace. From the viewpoint of further reducing the amount of scattering, the particle size of the molded body may be 10 mm or more, 30 mm or more, or 50 mm or more. From the viewpoint of sufficiently reducing unreacted inorganic matter remaining in the molten slag, the particle size of the molded body may be 90 mm or less, or 80 mm or less.

[0033] In this specification, the particle size of the molded body contained in the basicity adjusting agent is measured as the diameter of the circumscribed circle that circumscribes the two-dimensional image of the molded body. If the diameter of the circumscribed circle differs depending on the orientation when the molded body is imaged, the maximum value of the diameter shall be used as the particle size of the molded body.

[0034] The density of the molded body is 0.95 g / cm³. 3 The above is acceptable, and 1.0 g / cm³ 3 The above is acceptable, and 1.1 g / cm³ 3 The above is sufficient. Such molded articles are less prone to scattering and have even better shape retention. The density of the molded article is 1.9 g / cm³. 3 The following may be used: 1.6 g / cm³ 3 The following is also possible. Such a molded body has an even better basicity adjustment function. The density as used herein is the apparent density calculated from the volume measured using a caliper and the mass measured using a scale.

[0035] When the molded body containing the basicity adjusting agent is charged into a melting furnace and heated, the plastic melts and acts as a binder in the temperature range of approximately 400°C or below. This suppresses pulverization and maintains the shape of the molded body. Although the plastic decomposes in the temperature range above 400°C, the lignin contained in the biomass acts as a binder. This suppresses pulverization and maintains the shape of the molded body. In this way, pulverization is suppressed and the shape is maintained over a wide temperature range. In other words, this molded body has excellent shape retention. Therefore, even if the size of the lime source and silica source is small, the amount of scattering is sufficiently reduced, and it functions effectively as a basicity adjusting agent for molten slag.

[0036] A method for producing a basicity adjusting agent according to one embodiment includes a step of producing a molded body by pressurizing a raw material containing an inorganic substance including at least one of a lime source and a silica source, a plastic, and biomass while heated to a temperature range of 140 to 350°C. The types of inorganic substance (lime source and silica source), plastic, and biomass in the raw material are as described in the embodiment of the basicity adjusting agent. Furthermore, the content of inorganic substance, plastic, and biomass relative to the total raw material is as described in the embodiment of the basicity adjusting agent as the content relative to the total molded body. Granular inorganic substance can be used. As plastic, pellets or crushed waste plastic (plastic pieces) can be used. As biomass, wood chips obtained by crushing trees or waste wood can be used. The particle sizes of each may be the same as those contained in the molded body.

[0037] An example of a method for producing a basicity adjusting agent, as shown in Figure 1, includes the steps of: mixing inorganic materials containing at least one of a lime source and a silica source, plastic, and biomass; heating and molding the raw materials (mixed raw materials) obtained in this step to produce a molded body; and cooling the molded body.

[0038] By heating raw materials containing inorganic materials, plastics, and biomass to 140-350°C, a molded article in which the plastic has softened and is sufficiently densified can be obtained. The lower limit of the above temperature range during molding may be 160°C or 180°C from the viewpoint of further promoting densification. The upper limit of the above temperature range during molding may be 300°C or less or 250°C or less from the viewpoint of suppressing the decomposition of the plastic.

[0039] The pressure used during pressure molding (molding pressure) may be 5 MPa or higher, 6 MPa or higher, or 7 MPa or higher, from the viewpoint of obtaining a sufficiently densified molded body. The molding method is not particularly limited, and a method that allows molding while heating can be used as appropriate. For example, an RPF (Refuse derived paper and plastics densified fuel) molding machine may be used, or a hot press machine may be used. The heating and pressurizing time may be 2 to 30 minutes, or 5 to 20 minutes. Heating and pressurizing may be carried out in the atmosphere or in an inert gas atmosphere.

[0040] In this way, a basicity adjusting agent including a molded body is obtained, which is suitably used for adjusting the basicity of molten slag in a melting furnace. That is, the molded body is useful for adjusting the basicity of molten slag. However, the method for producing the basicity adjusting agent is not limited to the method described above.

[0041] A waste melting treatment method according to one embodiment is a waste melting treatment method in which waste, charcoal material, and auxiliary materials are charged into a melting furnace and melted, and the method includes a step of adjusting the basicity of the molten slag using a basicity adjusting agent containing the molded body described above. This waste melting treatment method can be carried out using, for example, a waste melting treatment facility 100 equipped with a coke bed type melting furnace 40 as shown in Figure 2.

[0042] The waste melting treatment facility 100 in Figure 2 comprises a coke bed type melting furnace 40 and a charging device 50 provided above the melting furnace 40. The melting furnace 40 has a shaft section 42, a bell section 44 provided at the lower end of the shaft section 42, and a furnace bottom section 46 provided below the bell section 44. From the shaft section 42 to the furnace bottom section 46, upper tuyeres 45 for the pyrolysis zone and lower tuyeres 47 for the combustion melting zone are provided in order from top to bottom. The upper tuyeres 45 and lower tuyeres 47 may each be provided in multiple stages.

[0043] Waste, charcoal, and auxiliary materials are charged into the melting furnace 40 by the charging device 50. Examples of waste include general waste, industrial waste, processed materials such as incinerated ash obtained by drying, incinerating, crushing, etc., and landfill waste containing soil and sand that has been excavated after being landfilled. Auxiliary materials may include the basicity adjusting agent mentioned above. In addition to the basicity adjusting agent, auxiliary materials may include at least one selected from iron ore, magnesia, periclase, kudolithite, and jamonite. By using such auxiliary materials, the waste 48 can be sufficiently melted inside the melting furnace 40. As charcoal, coal, coke, or molded charcoal can be used.

[0044] Waste, charcoal, and auxiliary materials are charged into the melting furnace 40 from the charging device 50. Oxygen or oxygen-enriched air is supplied from the lower tuyere 47, and air is supplied as a combustion support gas from the upper tuyere 45. The charcoal charged into the melting furnace 40 is burned by the oxygen or oxygen-enriched air supplied from the lower tuyere 47 and functions as a heat source. The waste 48, including auxiliary materials, charged into the melting furnace 40 is heated to, for example, 1600°C or higher by the combustion of the charcoal, becoming a pyrolysis residue 43. The pyrolysis residue 43 is burned mainly by air supplied from the upper tuyere 45.

[0045] The pyrolysis gas generated in the melting furnace 40 rises up the shaft section 42 and is introduced into the combustion chamber through the exhaust gas pipe 52 connected to the lower part of the charging device 50. The combustion exhaust gas is burned as a combustible gas and then the waste heat is recovered in the boiler. After that, the exhaust gas is cooled in a cooling tower, then passes through a dust collector and a catalytic reaction tower before being discharged from the chimney.

[0046] A temperature gradient is created inside the melting furnace 40 by the combustion of carbon material and other materials. Specifically, the melting furnace 40 has a drying / pre-heating zone 40a, a pyrolysis zone 40b, and a combustion / melting zone 40c, extending from top to bottom. The basicity adjusting agent introduced into the melting furnace 40 from the charging device 50, along with the waste and carbon material, reaches the drying / pre-heating zone 40a, the pyrolysis zone 40b, and the combustion / melting zone 40c in that order. In the drying / pre-heating zone 40a, the plastic contained in the molded body of the basicity adjusting agent functions as a binder. In the pyrolysis zone 40b and the combustion / melting zone 40c, the biomass contained in the molded body of the basicity adjusting agent functions as a binder. In this way, the inorganic materials contained in the basicity adjusting agent reach the combustion / melting zone 40c.

[0047] The combustible components in the waste 48 and the plastics and biomass contained in the molded body of the basicity adjuster are gasified and rise within the melting furnace 40, and are introduced into the combustion chamber via the exhaust gas pipe 52. Meanwhile, the ash becomes molten slag via the pyrolysis residue 43. The lime source and silica source contained in the molded body of the basicity adjuster function as basicity adjusters for the molten slag. The molten slag with adjusted basicity flows down the coke packed bed 41 at the bottom of the furnace 46 and is discharged from the slag outlet 49.

[0048] The maximum temperature of the melting furnace 40 may be, for example, 1600°C or higher in the combustion / melting zone 40c. The molded body containing the basicity adjusting agent charged from the charging device 50 can maintain its shape for a while after being introduced into the melting furnace 40. During this time, pulverization of the molded body is suppressed, thus suppressing the scattering of inorganic matter. As a result, the inorganic matter contained in the molded body functions sufficiently as a basicity adjusting agent for the molten slag. The amount of basicity adjusting agent charged from the charging device 50 may be adjusted so that the basicity (CaO / SiO2) of the molten slag discharged from the outlet 49 of the melting furnace 40 is, for example, 0.7 to 1.0. As a result, molten slag with excellent fluidity is discharged from the outlet 49.

[0049] The discharge of molten slag from the discharge port 49 may be continuous (continuous discharge) or intermittent (intermittent discharge). The interval between discharges in the case of intermittent discharge may be, for example, 30 minutes or more, or 1 hour or more. The molten slag discharged from the discharge port 49 may be introduced into a water granulation tank containing cooling water and granulated. In this way, according to the waste melting treatment method described above, the discharge of lime source or silicon source from the exhaust gas pipe 52 is suppressed, and lime source or silicon source having a small size can be effectively utilized for adjusting the basicity of the molten slag. Furthermore, since the plastic and biomass contained in the basicity adjusting agent can also be used as a fuel source, the amount of carbon material charged from the charging device 50 can be reduced.

[0050] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited in any way to the above embodiment. For example, the structure and shape of the waste melting treatment equipment are not limited to those shown in the figures. [Examples]

[0051] The contents of this disclosure will be described in more detail with reference to the examples and comparative examples, but this disclosure is not limited to the following examples.

[0052] <Changes in scattering rate depending on particle size> (Comparative Example 1) A cylindrical body (inner diameter: 445 mm, length: 1000 mm) was fixed with its central axis oriented vertically. Approximately 10 g of limestone (particle size: ≤0.3 mm) was placed on a mesh support structure erected 600 mm above the bottom of the cylinder. Air was circulated at a flow rate of 0.5 m / s from bottom to top in the hollow section of the cylinder to cause the limestone on the support structure to be stirred up. The mass of limestone remaining on the support structure (w1) was measured 5 minutes after the start of air circulation. The scattering rate was calculated from this mass (w1) and the mass of limestone placed on the support structure before the start of air circulation (w0) using the following formula. Scattering rate (%)=(w0-W1) / w0×100

[0053] The same experiment was conducted by changing the airflow velocity to 1.0 m / s and 2.5 m / s, and the dispersion rate at each velocity was determined. The results are shown in Table 1.

[0054] (Example 1) The raw materials obtained by mixing granular limestone (particle size: ≤0.3 mm), waste plastic fragments (particle size: ≤30 mm), and wood chips obtained by crushing construction waste (particle size: ≤30 mm) in a ratio of 30% by mass:20% by mass:50% by mass are molded in an RPF molding machine into cylindrical molded bodies (diameter: approximately 3.5 cm, length: approximately 6 cm, volume: approximately 58 cm³). 3 , Density: 1.25g / cm 3 The following was obtained. The molding temperature was 150°C, the molding pressure was 58 MPa, the molding time was 2 minutes, and the atmosphere was air. Except for using this molded body, the scattering rate at each flow velocity was determined in the same manner as in Experimental Example 1. The results are shown in Table 1.

[0055] [Table 1]

[0056] As shown in Table 1, it was confirmed that scattering can be suppressed by forming a molded body from limestone with a particle size of 0.3 mm or less.

[0057] <Changes in shape stability due to the composition of the molded body 1> (Examples 2-4, Comparative Examples 2-6) Granular limestone (particle size: ≤1.0 mm), polypropylene pellets (PP, particle size: ≤30 mm), and wood chips obtained by crushing construction waste (particle size: ≤30 mm) were prepared. These were mixed in the mass ratios shown in Table 2 to prepare the raw materials. These raw materials were molded in an air-filled hot press to obtain cylindrical molded bodies (diameter: approximately 40 mm, length: approximately 30 mm, mass: approximately 40 g). The hot press was performed under the conditions of a temperature of 180°C, a molding pressure of 20 MPa, and a molding time of 10 minutes. The volume of the obtained molded bodies was measured using calipers. The density (apparent density) was calculated from this volume and mass. The results are shown in Table 2.

[0058] The crushing strength of the molded body at room temperature (20°C) was measured. The crushing strength was measured using the measuring device 10 shown in Figure 3. Specifically, the molded body 16 was placed on a support plate 17 located on the bottom plate of a frame 18, so that the circumferential surface of the molded body 16 was in contact with the upper surface of the support plate 17. Then, a movable plate 14, which is attached to the frame 18 so as to be able to move up and down, was lowered to sandwich the molded body 16 between the movable plate 14 and the support plate 17. A load was then applied to the molded body 16 in the radial direction by operating the movable plate 14. The crushing strength was finally determined from the load at which the molded body 16 broke. The results are shown in Table 2.

[0059] The shape retention of the molded article at room temperature (20°C) and after carbonization at 900°C for 2 hours were evaluated. The evaluation criteria were as follows. The evaluation results are shown in Table 2. A: It hardly turns into powder, and the shape of the molded body is well maintained. B: Powdering has occurred, and the shape of the molded product is not adequately maintained. C: Powdering has occurred, and the shape of the molded product is hardly retained.

[0060] [Table 2]

[0061] As shown in Table 2, the molded articles of Examples 2-4, which contained limestone along with predetermined amounts of polypropylene and wood chips, retained their shape well even after carbonization. Furthermore, they possessed sufficiently high crush strength. On the other hand, Comparative Example 2, which did not contain wood chips, and Comparative Examples 3 and 4, which had low wood chip content, exhibited sufficiently high crush strength at room temperature, but were found to be unable to retain their shape after carbonization. In addition, Comparative Example 6, which did not contain plastic, and Comparative Example 5, which had a low plastic content, had low crush strength at room temperature and were unable to retain their shape even before carbonization.

[0062] <Changes in shape stability due to the composition of the molded body 2> (Examples 5-7, Comparative Examples 7-11) Except for using granular limestone (particle size: ≤0.3 mm), molded bodies were obtained using the same procedure as in Examples 2-4 and Comparative Examples 2-6. The molded bodies were evaluated using the same procedure as in Examples 2-4 and Comparative Examples 2-6. The results are shown in Table 3.

[0063] [Table 3]

[0064] Figure 4 shows the relationship between the polypropylene content in the entire molded body and the crushing strength, as shown in Table 3. As shown in Table 3 and Figure 4, the molded bodies of Examples 5-7 (Group 2 in Figure 4), which contained a predetermined amount of polypropylene and wood chips along with limestone, had high crushing strength and retained their shape well after carbonization. On the other hand, the molded bodies of Comparative Examples 7-9 (Group 3 in Figure 4), which had a high polypropylene content and a low wood chip content, showed high crushing strength at room temperature, but were found not to retain their shape after carbonization. Comparative Examples 10 and 11 (Group 1 in Figure 4), which had a low polypropylene content, had low crushing strength at room temperature and did not retain their shape well. Comparing the crushing strength of the molded bodies in Table 2 and Table 3, the molded bodies in Table 2 had higher crushing strength. This indicates that crushing strength tends to decrease as the particle size of the limestone decreases.

[0065] <Consideration of the proportion of lime sources> (Example 8, Comparative Examples 12, 13) As shown in Table 4, molded bodies were obtained using the same procedure as in Example 4, except that the mixing ratio of granular limestone and wood chips was changed. The molded bodies were evaluated using the same procedure as in Examples 5-7 and Comparative Examples 7-11. The results are shown in Table 4. The results for Example 4 are also listed again in Table 5.

[0066] [Table 4]

[0067] As shown in Table 4, even when the proportion of limestone was increased, it was confirmed that the molded article of Example 8, which contains a predetermined amount of polypropylene and wood chips, could sufficiently maintain its shape after carbonization. Comparative Example 12, although excellent in shape retention, does not contain a lime source and therefore does not qualify as a basicity adjusting agent.

[0068] <Consideration of molding pressure 1> (Examples 9-11) Except for changing the molding pressure used to produce the molded bodies as shown in Table 5, the molded bodies of Examples 9 to 11 were produced using the same procedure as in Example 4. These molded bodies were then evaluated using the same procedure as in Example 4. The results are shown in Table 5. The results of Example 4 are also included again in Table 5.

[0069] [Table 5]

[0070] As shown in Table 5, it was confirmed that sufficient shape retention could be maintained even when the molding pressure was changed.

[0071] <Consideration of molding pressure 2> (Examples 12, 13) Except for changing the molding pressure used to produce the molded bodies as shown in Table 6, the molded bodies of Examples 12 and 13 were produced using the same procedure as in Example 2. These molded bodies were then evaluated using the same procedure as in Example 2. The results are shown in Table 6. The results for Example 2 are also included again in Table 6.

[0072] (Comparative Examples 14, 15) Except for changing the pressure used to produce the molded bodies as shown in Table 6, the molded bodies of Comparative Examples 14 and 15 were produced using the same procedure as Comparative Example 3. These molded bodies were then evaluated using the same procedure as Comparative Example 3. The results are shown in Table 6. The results for Comparative Example 3 are also included again in Table 6.

[0073] [Table 6]

[0074] The results from Examples 12, 13, and 2 in Table 6 confirm that the shape of the molded body can be sufficiently maintained even when the molding pressure is changed. On the other hand, in Comparative Examples 14, 15, and 3, which had a low wood chip content, the density of the molded bodies improved when the molding pressure was increased, but the shape of the molded bodies could not be maintained after carbonization.

[0075] Figure 5 shows the relationship between molding pressure and the density of the molded article for each example and comparative example shown in Tables 5 and 6. In Figure 5, black circles represent data with a plastic (PP) content of 20% by mass, white triangles represent data with a plastic (PP) content of 40% by mass, and black squares represent data with a plastic (PP) content of 60% by mass. As shown in Figure 5, it was confirmed that when the proportion of plastic is excessive (60% by mass, black square), the density of the molded article does not increase significantly even when the molding pressure is increased.

[0076] <Evaluation of shape retention by carbonization> (Example 14) Granular limestone (particle size: ≤ 0.3 mm), waste plastic pieces (particle size: ≤ 30 mm), and wood chips (particle size: ≤ 30 mm) obtained by crushing construction waste materials were mixed at a ratio of 30% by mass: 20% by mass: 50% by mass, and the resulting raw material was formed using an RPF molding machine to obtain a cylindrical molded body (diameter: 35.01 mm, length: 61.11 mm, mass: 74.24 g, density: 1.26 g / cm 3 ). The temperature during molding was 150 °C, the molding pressure was 58 MPa, the molding time was 2 minutes, and the atmosphere was air. The appearance of the molded body at room temperature was as shown in Fig. 6(A).

[0077] This molded body was carbonized under the conditions of 900 °C for 2 hours. After carbonization, the diameter of the molded body was 32.09 mm, the length was 79.15 mm, the mass was 21.19 g, and the density was 0.33 g / cm 3 . The ratio of the mass after carbonization to the mass before carbonization was 28.5%. From this ratio, it is inferred that the waste plastic pieces contained in the molded body almost disappeared. Also, it is inferred that about 80% of the wood chips volatilized, and the limestone decreased in mass by the amount of carbon dioxide due to thermal decomposition (CaCO3 → CaO + CO2). The appearance of the molded body after carbonization was as shown in Fig. 6(B). The molded body after carbonization sufficiently retained the shape before carbonization, and it was confirmed that the shape retention was excellent. When evaluating the shape retention of this molded body according to the above evaluation criteria, it was "A".

Industrial Applicability

[0078] There is provided a basicity adjuster that can be effectively used for adjusting the basicity even when the size of the lime source or silica source is fine, and a method for producing the same. There is provided a waste melting treatment method that can be effectively used for adjusting the basicity even when the size of the lime source or silica source is fine.

Explanation of Symbols

[0079] 10... Measuring device, 14... Movable plate, 16... Molded body, 17... Support plate, 18... Frame, 40... Melting furnace, 40a... Drying / preheating zone, 40b... Pyrolysis zone, 40c... Combustion / melting zone, 41... Coke packed bed, 42... Shaft section, 43... Pyrolysis residue, 44... Morning glory section, 45... Upper tuyere, 46... Furnace bottom, 47... Lower tuyere, 48... Waste, 49... Slag outlet, 50... Charging device, 52... Exhaust gas pipe, 100... Waste melting treatment equipment.

Claims

1. The molded body contains an inorganic material including at least one of a lime source and a silica source, plastic, and biomass. The plastic content relative to the entire molded body is 20% by mass or more and less than 50% by mass. The biomass content relative to the entire molded body is 20% by mass or more. The inorganic substance includes particles having a particle size of 1 mm or less. The basicity adjusting agent wherein the particle size of the molded body is 5 to 100 mm.

2. The inorganic substance includes the lime source, The basicity adjusting agent according to claim 1, wherein the content of the lime source relative to the entire molded body is 10 to 60% by mass.

3. The basicity adjusting agent according to claim 1 or 2, wherein the plastic includes a thermoplastic and the biomass includes woody biomass.

4. The density of the molded body is 0.95 g / cm³. ３ The basicity adjusting agent according to any one of claims 1 to 3.

5. The process includes a step of producing a molded body by pressurizing a raw material containing an inorganic substance containing at least one of a lime source and a silica source, plastic, and biomass while heating it to 140 to 350°C. The inorganic material contains particles having a particle size of 1 mm or less, and the particle size of the molded body is 5 to 100 mm. A method for producing a basicity adjusting agent including the molded article, wherein the content of the plastic relative to the total raw materials is 20% by mass or more and less than 50% by mass, and the content of the biomass relative to the total raw materials is 20% by mass or more.

6. A waste melting treatment method in which waste is charged into a melting furnace and melted, A waste melting treatment method comprising a step of adjusting the basicity of molten slag using a basicity adjusting agent described in any one of claims 1 to 4.

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