Method for manufacturing water-absorbing material

Abstract

To provide a water absorbing material that utilizes incinerated ash while reducing energy consumption required for its production.SOLUTION: A method for producing a water absorbing material includes: an acquisition step for acquiring incinerated ash, which consists of burnt organic materials; an incinerated ash sorting step for sorting out a portion of the incinerated ash; and a carbonation step for carbonating the sorted-out incinerated ash in an atmosphere of a gas containing carbon dioxide to turn the incinerated ash into a water absorbing material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a water absorbent material.

Background Art

[0002] Conventionally, techniques for reusing waste incineration ash after various treatments have been known. For example, Patent Document 1 discloses a soil improver obtained by generating incineration ash from waste generated in the papermaking process, for example, by reburning, and combining the incineration ash with an organic polymer material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the reuse of waste, a function as a water absorbent material may be required. Here, the soil improver described in Patent Document 1 improves its water absorbency by combining a polymer material having high water absorbency with the original incineration ash. However, there is a problem that relatively large energy is required for the firing treatment to generate the incineration ash.

[0005] The present invention has been made in view of the above, and an object thereof is to obtain a water absorbent material using incineration ash while suppressing the energy consumption required for production.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, a method for manufacturing a water-absorbing material according to the present invention includes an acquisition step of acquiring incineration ash generated by burning an organic substance, an incineration ash selection step of selecting a part of the incineration ash from the incineration ash, and a carbonation step of carbonating the selected target incineration ash in an atmosphere of a gas containing carbon dioxide to obtain the target incineration ash as a water-absorbing material.

Advantages of the Invention

[0007] The method for manufacturing a water-absorbing material according to the present invention has an effect that a water-absorbing material using incineration ash can be obtained while suppressing energy consumption required for production.

Brief Description of the Drawings

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of a method for manufacturing a water-absorbing material according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by these embodiments.

[0010] [Embodiment] FIG. 1 is an explanatory diagram showing an example of a processing system used in the method for manufacturing a water-absorbing material according to the embodiment. A processing system (water-absorbing material manufacturing system) 10 burns organic substances to generate incineration ash, and selects target incineration ash, which is the incineration ash to be processed, from the generated incineration ash. The processing system 10 performs a water addition treatment on the target incineration ash and then performs a carbonation treatment to create a water-absorbing material.

[0011] As shown in FIG. 1, the processing system 10 includes an incineration ash manufacturing device 12, a selection device 14, a moisture supply device 16, and a carbonation treatment device 18. The incineration ash manufacturing device 12 burns organic substances to manufacture incineration ash. The incineration ash manufacturing device 12 includes an incinerator that burns garbage, a combustor that burns a fuel containing carbon, such as a boiler, and a recovery device that recovers incineration ash contained in exhaust gas. The combustion ash manufacturing device 12 manufactures, as incineration ash, main ash deposited at the bottom of the incinerator and the combustor, and fly ash recovered by the recovery device. Also, the components of the incineration ash manufactured by the incineration ash manufacturing device 12 differ depending on the organic substances being burned. The incineration ash manufacturing device 12 can use various devices that burn organic substances for purposes such as waste treatment, power generation, and heat energy acquisition. Further, the combustion ash manufacturing device 12 can use a device that burns organic substances based on the main purpose of the device and as a result generates combustion ash, but it may also be a device whose purpose is to generate combustion ash. The processing system 10 of the present embodiment has an incineration ash manufacturing device 12 equipped with a combustion facility, but is not limited thereto. The processing system 10 only needs to be able to acquire incineration ash, and may acquire incineration ash manufactured at another location using a transport device that transports the incineration ash.

[0012] The selection device 14 selects the incineration ash to be processed from the acquired incineration ash. That is, the selection device 14 excludes the incineration ash that is not processed into the water-absorbing material from the incineration ash produced by the incineration ash production device 12. The selection device 14 of the present embodiment recovers the incineration ash from the part where the incineration ash used for the water-absorbing material of the incineration ash production facility 12 is produced.

[0013] The moisture supply device 16 supplies moisture to the incineration ash. The moisture supply device 16 includes a water supply unit that supplies moisture to the incineration ash and a kneading unit that kneads the incineration ash to equalize the moisture of the incineration ash. The moisture supply device 16 equalizes the moisture contained in the combustion ash by supplying moisture to the combustion ash in the water supply unit and then kneading it in the kneading unit. The supply of moisture and kneading may be performed simultaneously, that is, moisture may be supplied while kneading the incineration ash.

[0014] The carbonation treatment device 18 supplies carbon dioxide (CO2) to the incineration ash with the adjusted moisture content and carbonates the incineration ash to produce a water-absorbing material. The carbonation treatment device 18 includes a treatment cylinder 20, a carbon dioxide gas supply unit 22, a gas supply pipe 24, and a flow meter 26. The carbon dioxide gas supply unit 22 is a tank that stores the carbon dioxide gas (CO2 gas) supplied to the treatment cylinder 20. The carbon dioxide gas supply unit 22 can use various gases containing CO2 at a certain ratio, for example, 0.04 mass% or more. The carbon dioxide gas supply unit 22 may supply the exhaust gas discharged by burning a substance or the CO2 gas purified from the exhaust gas. The gas supply pipe 24 connects the carbon dioxide gas supply unit 22 and the treatment cylinder 20. The gas supply pipe 24 guides the carbon dioxide gas supplied from the carbon dioxide gas supply unit 22 to the treatment cylinder 20. The flow meter 26 measures the flow rate of the carbon dioxide gas flowing through the gas supply pipe 24.

[0015] The treatment cylinder 20 holds the incineration ash 30, supplies carbon dioxide gas, and carbonates the incineration ash 30 by making the space holding the incineration ash 30 a carbon dioxide atmosphere. The treatment cylinder 20 includes a cylinder main body 32, a drainage part 34, a lid part 36, a partition plate 38, a gas discharge pipe 42, a drain pipe 44, and valves 46 and 48.

[0016] The cylinder main body 32 is a cylindrical structure with an internal space. One end of the cylinder main body 32 is blocked by a drainage part 34. The drainage part 34 blocks the lower end of the cylinder main body 32 in the vertical direction. The drainage part 34 is connected to the gas supply pipe 24. The lower end of the cylinder main body 32 in the vertical direction is sealed by the drainage part 34, and the upper end is open. The partition plate 38 is arranged between the lower end of the cylinder main body 32 in the vertical direction and the drainage part 34. The partition plate 38 is a plate formed with a number of openings through which combustion ash cannot pass but gas and water can pass. The partition plate 38 supports the combustion ash 30 introduced into the cylinder main body 32 from the lower side in the vertical direction. The drain pipe 44 is connected to the drainage part 34. A valve 48 is provided on the drain pipe 44.

[0017] After the carbonation treatment device 18 puts the combustion ash 30 into the cylinder main body 32, it closes the valve 48 and fills the cylinder main body 32 with carbon dioxide gas by supplying carbon dioxide gas from the carbon dioxide gas supply part 22.

[0018] In addition, the treatment system 10 may further add other substances to the water-absorbing material produced by carbonating the incineration ash. Also, the treatment system 10 may integrate the carbonation treatment device 18 with the water supply device 16. In this case, water is supplied to the treatment cylinder 20, and unnecessary water is discharged from the drainage part 34. Further, the treatment system 10 may be provided with a rotating part for kneading inside the treatment cylinder 20, or may knead the combustion ash by vibrating the treatment cylinder 20 itself.

[0019] FIG. 2 is a flowchart showing an example of the method for manufacturing the water-absorbing material. The process shown in FIG. 2 is executed by an operator using each part of the treatment system 10. The operation of the treatment system 10 will be described below.

[0020] The processing system 10 acquires incineration ash (step S12). Specifically, the combustion ash production device 12 burns organic substances to generate incineration ash. The processing system 10 performs screening of the incineration ash (step S14). Specifically, among the combustion ash generated by the screening device 14, the combustion ash to be used as a water absorbent is screened and extracted as the target combustion ash. Next, the processing system 10 adds water to the incineration ash (step S16). Specifically, the water supply device 16 supplies a predetermined amount of water to the target combustion ash. Next, the processing system 10 carbonates the incineration ash (step S18). Specifically, in the carbonation treatment device 18, carbon dioxide is passed through the water-added incineration ash to carbonate the incineration ash, thereby generating a water absorbent.

[0021] Next, using examples, the method for manufacturing the water absorbent will be described in more detail. In this example, as the combustion ash, the main ash and fly ash generated by burning biomass fuel in the combustion ash generation device were evaluated. Also, as the fly ash, Sample A, Sample B, Sample C, Sample E, and Sample F were evaluated. As the main ash, Sample D was evaluated. Further, as comparative examples, Comparative Sample A and Comparative Sample B, which are the main ash of the combustion ash, were also evaluated.

[0022] In this evaluation, after adding water to the combustion ash to reach the water content shown in Table 1 below, it was kneaded. Then, a predetermined amount, 350 g in this example, was put into the cylinder body 32, and 100% concentration carbon dioxide gas was supplied at a ventilation rate of 0.1 L / min for 24 hours. The supplied carbon dioxide amount was 800 gCO2 / kgDW (the supply amount of CO2 per unit weight of the dried ash (DW)).

[0023]

Table 1

[0024] Also, the water retention amounts of the above combustion ash and the produced water absorbent were measured respectively. For measuring the water retention amount, 30 g of the sample to be measured is put on filter paper with a container such as a beaker placed below. Next, 10 ml of ion-exchanged water is dropped at a time from the surface of the sample. Then, ion-exchanged water is dropped 10 ml at a time until the filtrate permeates the filter paper and starts to drop into the container. The water retention amount is calculated by the following formula based on the amount of ion-exchanged water dropped (water supply amount), the amount of water dropped into the container (dropping amount), and the weight of the ash. Water retention amount (dry weight basis) = (Water supply amount - Dropping amount + Water content of the sample in its original state) / (Dry mass of the sample) Here, the water content of the sample in its original state is the original weight of the sample × Set moisture content.

[0025] Also, for each combustion ash, the amount of carbon dioxide absorbed by the carbonation treatment was measured. The pH of the combustion ash and the produced water absorbent was also measured. Furthermore, the passing mass of the particle size of the combustion ash was measured. The amount of carbon dioxide absorbed by the carbonation treatment for the combustion ash was estimated by the difference in the total carbon amount. The total carbon amount was measured by the combustion oxidation method. The passing mass of the particle size of the combustion ash was measured by the sedimentation method using a JIS A 1204 sieve.

[0026] The measurement results are shown in FIGS. 3 to 10. FIG. 3 is a graph showing an example of the water absorption amounts of the incineration ash and the water absorbent. FIG. 4 is a graph showing an example of the increase rate of the water absorption amount in the carbonation treatment. FIG. 5 is a graph showing an example of the carbon dioxide absorption amount. FIG. 6 is a graph showing the relationship between the increase rate of the water absorption amount and the carbon dioxide absorption amount. FIG. 7 is a graph showing an example of the pH of the incineration ash and the water absorbent. FIG. 8 is a graph showing the relationship between the carbon dioxide absorption amount of the incineration ash and the calcium elution concentration. FIG. 9 is a graph showing the passing mass of the particle size of the incineration ash. FIG. 10 is a graph showing the passing mass of the particle size of the incineration ash. FIGS. 6 and 8 show only the data of this example and do not show the data of the comparative example.

[0027] As shown in FIGS. 3 and 4, the MSB of the main ash, which is the combustion ash of this example, and the AHF, MSF, BEF, MEF, and MMF of all fly ashes can increase the water absorption amount by performing carbonation treatment. In contrast, it can be seen that the MMB and AHB, which are the combustion ashes of the comparative example, do not increase the water absorption amount by carbonation.

[0028] Next, as shown in FIGS. 5 and 6, it can be seen that this example and the comparative example can increase the CO2 absorption amount by performing carbonation treatment. Also, as shown in FIG. 6, it can be seen that by setting the CO2 absorption amount to 20 g / kgDW or less, the water absorption increase rate can be made 30% or more. Further, by setting the CO2 absorption amount to 30 g / kgDW or more, the absorption amount per unit weight of the incineration ash can be increased.

[0029] Next, as shown in FIG. 7, it can be seen that by setting the water content during carbonation treatment to 10% or more, the pH of the water absorbent after carbonation treatment can be made close to neutral.

[0030] Also, as shown in FIG. 8, the combustion ash used for the water absorbent has a Ca elution concentration of 100 mg / l or more.

[0031] Also, as shown in FIGS. 9 and 10, for the incineration ash of this example, in the case of fly ash, the component with a particle size of 1 mm or less accounts for 30% or more of the whole. Further, for the incineration ash of this example, in the case of fly ash, the component with a particle size of 0.075 mm or less accounts for 20% or more of the whole.

[0032] As described above, the method for manufacturing a water-absorbing material includes an acquisition step of obtaining incineration ash generated by burning organic matter, an incineration ash selection step of selecting a part of the incineration ash from the incineration ash, and a carbonation step of carbonating the selected target incineration ash in an atmosphere of a gas containing carbon dioxide to use the target incineration ash as a water-absorbing material. In this way, by selecting incineration ash, performing a predetermined water addition treatment on the selected incineration ash, and performing a carbonation treatment, a water-absorbing material with a larger water absorption capacity can be manufactured. Further, by using a material added with carbon dioxide as the water-absorbing material, carbon dioxide can be fixed in the water-absorbing material, and the carbon dioxide in the air can be reduced.

[0033] The selected incineration ash can be fly ash, and as described above, the water absorption amount can be further increased.

[0034] The selected incineration ash preferably has a component with a particle size of 1 mm or less accounting for 30% or more of the whole, and more preferably a component with a particle size of 0.075 mm or less accounting for 20% or more of the whole. By selecting incineration ash within the above range, the water absorption amount can be further increased.

[0035] The selected incineration ash preferably has a Ca elution concentration of 100 mg / L or more. By selecting incineration ash within the above range, the water absorption amount can be further increased.

[0036] Also, the selected incineration ash is preferably combustion ash generated by burning woody biomass. Thereby, as described above, the water absorption amount can be further increased.

[0037] For the carbonation treatment, the carbon dioxide absorption amount per unit weight of the incineration ash is preferably 1 g / kgDW or more and 20 g / kg or less. Thereby, the water absorption amount can be increased.

[0038] For the carbonation treatment, the carbon dioxide absorption amount per unit weight of the incineration ash is preferably 30 g / kgDW or more and 200 g / kg or less. Thereby, while increasing the water absorption amount, more carbon dioxide can be absorbed.

Description of Symbols

[0039] 10 Processing system 12 Incineration ash production device 14 Selection device 16 Moisture supply device 18 Carbonation treatment device 20 Processing cylinder 22 Carbon dioxide gas supply section 24 Gas supply pipe 26 Flow meter 30 Cylinder body 32 Incineration ash 34 Drainage section 38 Partition plate 44 Drain pipe 48 Valve

Claims

1. An acquisition step of acquiring incineration ash generated by burning organic matter; An incineration ash selection step of selecting incineration ash in which components having a particle size of 1 mm or less account for 30% or more of the whole from the incineration ash; A water addition step of supplying water to the selected incineration ash selected in the incineration ash selection step so that the water content of the selected incineration ash is 5% or more and 15% or less; A carbonation step of carbonating the selected incineration ash whose water content has been adjusted in the water addition step without firing in an atmosphere of a gas containing carbon dioxide to obtain a water absorbent, including: The method for producing a water absorbent according to claim 1, wherein the elution concentration of Ca in the selected incineration ash is 100 mg / L or more.

2. The method for producing a water absorbent according to claim 1, wherein the selected incineration ash is fly ash.

3. The method for producing a water absorbent according to claim 1, wherein the selected incineration ash has components with a particle size of 0.075 mm or less accounting for 20% or more of the whole.

4. The method for producing a water absorbent according to any one of claims 1 to 3, wherein the selected incineration ash is combustion ash generated by burning woody biomass.

5. The method for producing a water absorbent according to any one of claims 1 to 4, wherein the carbonation treatment has a carbon dioxide absorption amount per unit weight of the selected incineration ash of 1 g / kg DW or more and 20 g / kg DW or less.

6. The method for producing a water absorbent according to any one of claims 1 to 4, wherein the carbonation treatment has a carbon dioxide absorption amount per unit weight of the selected incineration ash of 30 g / kg DW or more and 200 g / kg DW or less.

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