Shredder covering soil material

Abstract

To provide covering soil material having CO2 adsorbing performance and having proper water permeability and compactibility.SOLUTION: Cover soil material contains a combustion by-product containing a Ca-containing compound.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cover material for covering waste. [Background technology]

[0002] In final waste disposal sites, the top of the landfilled waste is covered with soil to prevent it from scattering, etc. Patent Document 1 shows a soil covering material for final disposal sites that is characterized by using incineration ash from irrigation mud.

[0003] On the other hand, CO released into the atmosphere 2 It is known that an increase in the amount of CO2 can lead to rising temperatures and the occurrence of abnormal weather. 2 Reduce emissions of CO in the atmosphere 2 A technology to reduce CO 2 The gas to be treated containing the above-mentioned is contacted with a dispersion liquid containing biomass incineration ash, and the CO contained in the gas to be treated is dissolved in the biomass incineration ash. 2 CO adsorbed 2 Techniques for producing immobilized materials are disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-50958 A [Patent Document 2] JP 2020-175318 A Summary of the Invention [Problem to be solved by the invention]

[0005] Although the soil cover material in Patent Document 1 can use irrigation mud from rivers, there is a demand for soil cover materials with new functionality. 2The immobilization material is dispersed in water and is not suitable for being buried in a final disposal site. In particular, the covering soil must have adequate permeability to decompose the waste and adequate compaction properties to cover and immobilize the waste. [Means for solving the problem]

[0006] One example of the means for solving the problems of the present invention is a cover soil material containing combustion by-products that contain Ca-containing compounds.

[0007] Preferably, the combustion by-product is soot and dust generated during incineration in a combustion facility.

[0008] Preferably, the cover material further comprises sludge and slag.

[0009] Preferably, the combustion by-products constitute 10 to 40% by weight, with the total weight of the soil covering material being 100% by weight.

[0010] Preferably, the soil cover material contains 30 to 50% by weight of the sludge, with the total weight of the soil cover material being 100% by weight.

[0011] Preferably, the soil cover material contains 20 to 40% by weight of the slag, with the total weight of the soil cover material being 100% by weight.

[0012] Another example of the means for solving the problem of the present invention is a covering soil in which the covering soil material is adjusted to have an optimal moisture content of ±10%.

[0013] Yet another example of the means for solving the problems of the present invention is a soil cover in which water is added to the soil cover material to adjust the moisture content to 10 to 50%. [Brief description of the drawings]

[0014] [Figure 1] Figure 1 shows the relationship between the passing mass percentage (%) and particle size (mm) of the components of the cover soil material, the recycled cover soil, and the existing cover soil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the covering material of an embodiment of the present invention will be described. The drawings and tables used in this embodiment are for the purpose of explaining the configuration, arrangement, function, operation, and effects of the present invention, and do not limit the specific components, numerical values, etc. of the present invention.

[0016] <Covering material> In the present application, the covering soil refers to what covers the surface of the waste layer when waste is landfilled, and the covering material refers to the material used for the covering soil. The covering material may mainly contain each material described below, and may also contain any other material.

[0017] <Ca-containing compound> In the present application, as the Ca-containing compound, any Ca-containing compound that can adsorb carbon dioxide (hereinafter referred to as CO 2 ) can be used. A typical example of the Ca-containing compound is slaked lime. Alternatively, quicklime, calcium chloride, calcium sulfate, etc. can be used as the Ca-containing compound. Note that the notation "Ca-containing compound" includes the meaning of a compound containing Ca in the state of Ca 2+ .

[0018] <Combustion by-products> In the present application, the combustion by-products can be soot (dust), combustion ash, cinder, or a mixture thereof generated when incinerated in a combustion facility. Typically, the combustion by-products are soot. Examples of the combustion facility include a waste treatment facility and a factory facility.

[0019] The combustion by-products are preferably 10 to 40% by weight based on 100% by weight of the total weight of the covering material. More preferably, the combustion by-products are 25 to 35% by weight based on 100% by weight of the total weight of the covering material. It is preferable that the combustion by-products are 20% by weight or more based on 100% by weight of the total weight of the covering material because it is effective for water permeability, and it is preferable that they are less than 40% by weight because it is effective for compaction.

[0020] The combustion by-product containing the Ca-containing compound can be formed, for example, by chemically reacting the Ca-containing compound with the combusted exhaust gas. Examples of the method of chemical reaction include spraying and slurry immersion. For example, when soot and dust are used as the combustion by-product and slaked lime is used as the Ca-containing compound, the combustion by-product containing the Ca-containing compound can be formed by spraying slaked lime into the exhaust gas. Since the acidity of the combustion by-product depends on the acidity of the original waste, it is preferable to set the amount of the Ca-containing compound to be blown in so that the acidity is equal to or less than a certain exhaust gas standard value in accordance with the exhaust gas standard of the Air Pollution Control Act. When soot and slaked lime are used as the combustion by-product and the Ca-containing compound, respectively, it is typically preferable to spray a certain amount or more (excessive amount) of slaked lime so as not to exceed the exhaust gas standard value.

[0021] <Dust> Dust refers to fine particles that are generated and scattered when something is burned. In this application, dust refers to dust generated in a combustion facility and collected by equipment. Typically, dust is mainly composed of silt, as described below.

[0022] In this application, the particle size ranges of each component are as follows: coarse gravel: 75-19 mm, medium gravel: 19-4.75 mm, fine gravel: 4.75-2 mm, coarse sand: 2-0.850 mm, medium sand: 0.850-0.250 mm, fine sand: 0.250-0.075 mm, silt: 0.075-0.005 mm, clay: 0.005-. In this application, particle size is the median diameter (d50). The numerical range includes the lower limit value itself but does not include the upper limit value itself.

[0023] <Sludge> In this application, sludge refers to a muddy substance that is formed by settling or floating up suspended matter in water. In this application, sludge collected from rivers or the like can be used. As the sludge, dewatered sludge, mechanically dried sludge, or sun-dried sludge can be preferably used. The drying method of the dried sludge is optional. The sludge is typically mainly composed of sand and silt.

[0024] The sludge is preferably 30 to 50% by weight, with the total weight of the soil covering material being 100% by weight. More preferably, the sludge is 35 to 45% by weight, with the total weight of the soil covering material being 100% by weight. When the sludge is 30% by weight or more, with the total weight of the soil covering material being 100% by weight, it is preferable because it is effective in improving water permeability, and when it is less than 50% by weight, it is preferable because it is effective in compaction.

[0025] The moisture content of the sludge may be any moisture content so long as the moisture content of the entire covering soil falls within an appropriate range for covering soil. In other words, the sludge of the present invention is not limited to dewatered sludge, mechanically dried sludge, or sun-dried sludge, and may be sludge containing a moisture content that can be appropriately adjusted for use as covering soil. The present invention includes not only covering soil obtained by mixing dried sludge with other materials and then adding moisture, but also covering soil obtained by mixing moist sludge with soot and dust (and drying it if necessary) and adjusting the moisture content to the final value.

[0026] <Slug> In this application, slag refers to a residue generated when waste is melted and disposed of. In this application, slag obtained from a waste incineration plant or the like can be used. Typically, slag is mainly composed of sand.

[0027] The slag is preferably 20-40% by weight, with the total weight of the soil covering material being 100% by weight. More preferably, the slag is 25-35% by weight, with the total weight of the soil covering material being 100% by weight. If the slag is 20% by weight or more, with the total weight of the soil covering material being 100% by weight, this is effective for improving permeability, and if it is less than 40% by weight, this is effective for compaction.

[0028] <Water content ratio> In this application, the moisture content refers to the moisture content of the cover soil, typically the optimum moisture content of the cover soil formed using the cover soil material. In addition, in this application, the optimum moisture content refers to the optimum moisture content specified in JIS A 1210. The optimum moisture content can be calculated by performing a soil compaction test by tamping specified in JIS A 1210. When water is added to the cover soil material to be used as cover soil, the moisture content is preferably an appropriate moisture content according to the cover soil material, and is set to the above optimum moisture content ±10%. If the moisture content of the cover soil is the optimum moisture content ±10%, it is preferable because it is effective for compaction. In the case of the cover soil material used in the examples described later, the optimum moisture content is 36%, and the moisture content of the cover soil is 36% ±10%, preferably 36% ±5%, and more preferably 36% ±2%. In other words, in the case of the soil cover material used in the examples described later, the moisture content of the soil cover is 26 to 46%, preferably 31 to 41%, and more preferably 34 to 38%. The moisture content of the soil cover varies depending on the soil cover material, but is about 10 to 50%. Note that in the present application, the moisture content may also be the moisture content of the soil cover formed using the soil cover material.

[0029] As a result of intensive research, the inventors have found that when combustion by-products contain Ca-containing compounds, they are suitable as cover materials with compactibility and water permeability. In addition, by using combustion by-products when covering waste, the combustion by-products can be effectively utilized, and the inclusion of Ca-containing compounds in the combustion by-products reduces CO 2 It was found that it is possible to provide a soil cover material that also has an adsorption function. 2 Adsorption can be carried out by adsorption onto combustion by-products (eg, soot and dust) containing Ca-containing compounds before the production of the soil cover material, onto the soil cover material, or onto the soil cover. EXAMPLES

[0030] The covering material used in Example 1 had the composition shown in Table 1 below.

[0031] [Table 1]

[0032] The main raw material, sludge a, is sludge obtained from a water purification plant. Slag b is slag obtained from a waste incineration plant. Dust c is dust obtained from a paper mill. Dust d is dust obtained from a paper mill. Dust e is dust obtained from a purification center. These raw materials were mixed in the proportions shown in Table 2 to ensure a uniform particle size distribution and used as the cover soil material.

[0033] [Table 2]

[0034] To maximize the dry density, water was added to the covering material to make the moisture content 36% (360 L of water was added for every 1,000 kg of covering material. Hereafter, this will be referred to as "recycled covering soil"). To mix uniformly, the material was kneaded in a kneading machine. The amount of kneading was 6.25 m per hour. 3 After mixing, the 3 The products were stored in containers or loose in the product storage area.

[0035] The physical properties of the created recycled cover soil were compared with those of the existing cover soil (cover soil used at existing final disposal sites; hereafter referred to as existing cover soil) (see Table 3).

[0036] [Table 3]

[0037] Figure 1 shows the relationship between the passing mass percentage (%) and particle size (mm) of the components a to d of the cover soil material, the recycled cover soil X, and the existing cover soil Y. It can be seen that the particle size distribution of the recycled cover soil X is approaching that of the existing cover soil Y.

[0038] <Characteristics of recycled soil cover> (a) The optimum moisture content for compaction was set at 36%. (b) The maximum dry density when compacted was approximately 60% of that of the existing cover soil. (c) The unconfined compression strength was close to that of the existing covering soil. (d) Permeability is 40 times higher than that of the existing cover soil. (e) Since soot containing calcium is mixed in, it is possible to adsorb and fix carbon dioxide (although the adsorption capacity and amount of adsorption are unknown as they have not been measured).

[0039] From the above characteristics, it can be considered that (1) The optimum moisture content during compaction is high, and construction is carried out in a state with a high moisture content, so CO 2 It is possible to fix it by suction. (2) Because the maximum dry density is lower than that of the existing covering soil, there are many gaps and it has good permeability. By mixing small-particle-sized soot and dust with larger-particle-sized water purification plant sludge and molten slag, the particle size distribution of the recycled cover soil became more uniform.

[0040] When using small-grained sludge and combustion by-products as cover soil materials, simply mixing with large-grained slag will not compact well. On the other hand, if a Ca-containing compound is added to the combustion by-products mixed with the sludge, relatively large, dumpling-like particles will be formed, and it is assumed that these large particles will break down appropriately during compaction. Without being bound by a particular theory, it is thought that the particle size adjustment function of the combustion by-products containing this Ca-containing compound will allow the combustion by-products to be reused while reducing CO2 emissions from the Ca-containing compound. 2 It is believed that this will make it possible to form a covering soil material that also has adsorption functions.

[0041] Although three types of soot and dust are used, it has been confirmed that one or two types can also be used as covering material by adjusting the weight ratio appropriately.

[0042] The present invention is not limited to the above-described embodiments, and appropriate modifications and variations are possible without departing from the scope of the invention described in the specification and claims of this application.

Claims

1. A cover material comprising combustion by-products including Ca-containing compounds.

2. The soil covering material according to claim 1 , wherein the combustion by-product is soot and dust produced when incinerated in a combustion facility.

3. 10. The soil cover material of claim 1, further comprising sludge and slag.

4. 2. The soil cover material according to claim 1, wherein the combustion by-products constitute 10 to 40% by weight, with the total weight of the soil cover material being 100% by weight.

5. The soil cover material according to claim 3, wherein the sludge is contained in an amount of 30 to 50% by weight, with the total weight of the soil cover material being 100% by weight.

6. The soil cover material according to claim 3, wherein the slag is contained in an amount of 20 to 40% by weight, with the total weight of the soil cover material being 100% by weight.

7. A covering soil, the covering soil material according to claim 1 being adjusted to have an optimum moisture content of ±10%.

8. A soil cover material according to claim 1, wherein water is added to the soil cover material to adjust the moisture content to 10 to 50%.

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