Concrete sludge treatment apparatus

Abstract

To provide a concrete sludge treatment apparatus capable of reducing an amount of admixtures remaining in calcium carbonate recovered by simple treatment.SOLUTION: Concrete sludge treatment apparatus 100 includes a treatment tank 10 for storing concrete sludge and water, an organic component decomposition means 50 for decomposing organic components contained in the concrete sludge stored in the treatment tank 10, and a carbon dioxide gas introduction means 30 for introducing carbon dioxide gas into the treatment tank 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a concrete sludge treatment device. [Background technology]

[0002] Concrete sludge is generated during the concrete manufacturing process and as surplus after concrete is poured. Since disposal of concrete sludge requires environmental considerations, it is preferable to reuse it as part of cement raw materials.

[0003] One method of reuse is to add water to concrete sludge to form a slurry, then inject carbon dioxide (CO2) gas into this slurry, causing the calcium (Ca) component eluted from the cement particles into the water to come into gas-liquid contact with the carbon dioxide gas and react to produce calcium carbonate (CaCO3), and this product can be reused as part of the cement raw material (see, for example, Patent Document 1).

[0004] Concrete contains admixtures to improve its performance, and concrete sludge also contains admixtures. Because some of the admixtures are adsorbed onto the surface of cement particles, the leaching of calcium components is inhibited during the conventional process of recovering calcium components through gas-liquid contact. Furthermore, because the admixtures in the sludge are present in water, if the supernatant water is reused for concrete production, the admixtures may be unintentionally mixed into the concrete, resulting in quality defects. Furthermore, admixtures may remain in the recovered calcium components. In this case, if the recovered calcium components are used as a cement raw material or concrete admixture, the quality of the concrete may be affected.

[0005] Therefore, the first method for removing admixtures from concrete sludge is to wash the concrete sludge with water to separate it into a solid phase containing cementitious components and a liquid phase containing admixtures.

[0006] A second method for removing admixtures from concrete sludge involves drying the concrete sludge and then subjecting it to heat treatment to decompose the admixtures. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-138574 Summary of the Invention

[0008] However, because the admixtures are adsorbed onto the surfaces of cement particles, the admixtures cannot be sufficiently removed even by washing with water multiple times in the first method, and the water containing the admixtures cannot be reused for concrete production.

[0009] In addition, the second method requires that the concrete sludge solidified by heat treatment be crushed, dispersed in water to re-form a slurry, and then carbon dioxide gas is blown in to recover the calcium component, which increases the number of processing steps. [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a concrete sludge treatment device that can reduce the amount of admixture remaining in recovered calcium carbonate through a simple process. [Means for solving the problem]

[0011] The first concrete sludge treatment apparatus of the present invention is characterized by comprising a treatment tank for containing concrete sludge and water, an organic component decomposition means for decomposing organic components contained in the concrete sludge contained in the treatment tank, and a carbon dioxide gas introduction means for introducing carbon dioxide gas into the treatment tank.

[0012] According to the first concrete sludge treatment device of the present invention, the admixture mainly composed of organic components is decomposed by the organic component decomposition means, so that it is possible to easily reduce the amount of admixture remaining in the recovered calcium carbonate.

[0013] The second concrete sludge treatment apparatus of the present invention is characterized by comprising a first treatment tank for accommodating concrete sludge and water, an organic component decomposition means for decomposing organic components contained in the concrete sludge accommodated in the first treatment tank, a second treatment tank into which the contents of the first treatment tank are transferred, and a carbon dioxide gas introduction means for supplying carbon dioxide gas into the second treatment tank.

[0014] According to the second concrete sludge treatment device of the present invention, as in the first concrete sludge treatment device, the admixtures mainly composed of organic components are decomposed by the organic component decomposition means, so that it is possible to easily reduce the amount of admixture remaining in the recovered calcium carbonate. Furthermore, after the admixtures are decomposed in the first treatment tank, calcium is eluted from the cement particles into water and solidified as calcium carbonate in the second treatment tank, so that it is possible to further reduce the amount of remaining admixture.

[0015] In the first and second concrete sludge treatment apparatuses of the present invention, the organic component decomposition means is preferably a means for introducing ozone into the treatment tank or the first treatment tank.

[0016] In this case, it becomes possible to effectively decompose the admixture, the main component of which is organic, by ozone.

[0017] In the first and second concrete sludge treatment apparatuses of the present invention, the organic component decomposition means is preferably a means for introducing hydrogen peroxide into the treatment tank or the first treatment tank.

[0018] In this case, it becomes possible to effectively decompose the admixture, the main component of which is organic, with hydrogen peroxide.

[0019] In the first and second concrete sludge treatment apparatuses of the present invention, the organic component decomposition means is preferably a means for irradiating the inside of the treatment tank or the first treatment tank with ultraviolet rays.

[0020] In this case, it becomes possible to effectively decompose the admixture, which is mainly composed of organic components, by ultraviolet light. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of a concrete sludge treatment apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 5 is a schematic view of a concrete sludge treatment apparatus according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] A concrete sludge treatment apparatus 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. The concrete sludge treatment apparatus 100 solidifies and separates calcium components in concrete sludge.

[0023] The concrete sludge treatment apparatus 100 comprises a treatment tank 10, a sludge introducing means 20, a carbon dioxide gas introducing means 30, an agitating means 40, and an organic component decomposing means 50.

[0024] Water is stored inside the treatment tank 10. Although not shown, water may be supplied from outside into the treatment tank 10 by a water supply means such as a pump. Furthermore, although not shown, the treated water in the treatment tank 10 may be discharged to the outside by a water discharge means such as a pump.

[0025] The sludge introducing means 20 is a pipe that introduces concrete sludge into the bottom of the treatment tank 10. There are no restrictions on the shape or material of the sludge introducing means 20, as long as it allows the concrete sludge to flow smoothly through it. The concrete sludge may be concrete sludge generated in a concrete manufacturing plant, ready-mix concrete (residual concrete) left over at a construction site, etc., and it is preferable to remove the aggregate.

[0026] The carbon dioxide gas introducing means 30 is a pipe that introduces carbon dioxide (CO2) gas into the lower part of the treatment tank 10, and is equipped with a pump and a valve, not shown. The base end of the pipe that constitutes the carbon dioxide gas introducing means 30 is connected to a carbon dioxide gas supply source, not shown. The carbon dioxide gas supply source is, for example, a gas cylinder containing carbon dioxide gas. Exhaust gas containing a high concentration of carbon dioxide gas emitted from a cement or steel manufacturing plant or a power plant, or high-purity carbon dioxide gas recovered from this exhaust gas by a carbon dioxide recovery device using a chemical absorption method (amine method), etc., may be introduced through the carbon dioxide gas introducing means 30.

[0027] It is preferable to provide a disperser 31 at the tip of the carbon dioxide gas introducing means 30 so that the carbon dioxide gas can be finely dispersed and supplied into the treatment tank 10. The disperser 31 may have a large number of fine openings, or may be a microvalve or a nanobubble generator.

[0028] The stirring means 40 here is a rotor that is rotated by a rotary motor (not shown). The shape of the rotor is not limited. The stirring means 40 only needs to be able to suitably stir the contents contained in the treatment tank 10, and may be one that stirs by vibration, reciprocating motion, or the like.

[0029] The organic component decomposition means 50 decomposes organic components in the contents contained in the treatment tank 10. Here, the organic component decomposition means 50 is an ozone gas introduction means 60, a hydrogen peroxide introduction means 70, and an ultraviolet light irradiation means 80. However, it is sufficient that at least one of the ozone gas introduction means 60, the hydrogen peroxide introduction means 70, and the ultraviolet light irradiation means 80 is present as the organic component decomposition means 50. The organic component decomposition means 50 may be other means. However, components generated by the decomposition of organic components by the organic component decomposition means 50 must not adversely affect the properties of concrete, and preferably do not affect the properties of concrete.

[0030] Admixtures are used to improve the properties of concrete primarily through their surfactant action, and are classified into water-reducing agents, air-entraining agents, superplasticizers, and hydration heat inhibitors. Admixtures are basically composed of organic components. Therefore, admixtures can be decomposed into water, carbon dioxide gas, oxygen gas, nitrogen gas, etc. by the organic component decomposition means 50.

[0031] The ozone gas introduction means 60 is a pipe that introduces ozone (O3) gas into the lower part of the treatment tank 10, and is equipped with a pump and valves (not shown). The admixture decomposes when exposed to ozone gas. The base end of the pipe that constitutes the ozone gas introduction means 60 is connected to an ozone gas supply source (not shown). A commercially available ozone gas supply source may be used, such as an ozone generator that generates ozone gas by electrolyzing water. The tip of the ozone gas introduction means 60 is preferably equipped with a disperser 61 so that the ozone gas can be finely dispersed and supplied into the treatment tank 10. The disperser 61 may have many fine openings, or may be a microvalve, nanobubble generator, or the like.

[0032] The hydrogen peroxide introducing means 70 is a pipe that introduces hydrogen peroxide (H2O2) water into the contents of the treatment tank 10, and is equipped with a pump and valve (not shown). The admixture decomposes when it comes into contact with hydrogen peroxide. The base end of the pipe that constitutes the hydrogen peroxide introducing means 70 is connected to a hydrogen peroxide supply source (not shown). A commercially available hydrogen peroxide supply source may be used.

[0033] The ultraviolet irradiation means 80 is a device that irradiates ultraviolet rays onto the contents of the treatment tank 10. The admixture is decomposed by irradiation with ultraviolet rays. The ultraviolet irradiation means 80 may be a commercially available device, and may be, for example, a cylindrical device with a double-tube structure in which a glass tube is used as the outer tube and the ultraviolet irradiation device main body is provided in the inner tube. The ultraviolet irradiation device main body may be a general ultraviolet lamp. The ultraviolet irradiation means 80 may also be one that irradiates deep ultraviolet rays.

[0034] In the concrete sludge treatment apparatus 100 described above, concrete sludge is introduced into water contained in the treatment tank 10 through the sludge introducing means 20, and is stirred by the stirring means 40, thereby turning the concrete sludge into a slurry. Then, through stirring, the admixtures adsorbed to the surfaces of the cement particles in the slurried concrete sludge are decomposed by the organic component decomposition means 50. As a result, the admixtures on the surfaces of the cement particles are decomposed and removed, making it easier for the calcium components of the cement particles to dissolve into the water. The admixtures that were mixed into the concrete sludge are released into the water and decomposed by the organic component decomposition means 50.

[0035] The admixture is decomposed into water, carbon dioxide gas, oxygen gas, nitrogen gas, etc. by the organic component decomposition means 50. The water generated by the decomposition is mixed with the water already in the treatment tank 10. The carbon dioxide gas generated by the decomposition reacts with the eluted calcium component to produce calcium carbonate, which accumulates at the bottom of the treatment tank 10. The remaining carbon dioxide gas then rises as bubbles and is released into the atmosphere. The oxygen gas and nitrogen gas also rise as bubbles and are released into the atmosphere.

[0036] Carbon dioxide gas is also introduced into the treatment tank 10 from the carbon dioxide gas introduction means 30, which also causes calcium components eluted from the surfaces of the cement particles into the water to react with the carbon dioxide to produce calcium carbonate, which accumulates in the lower part of the treatment tank 10. The calcium carbonate that accumulates in the lower part is then allowed to settle and recovered. Since the admixtures are decomposed by the organic component decomposition means 50, there is little admixture mixed in with the recovered calcium carbonate. The remaining carbon dioxide gas rises as bubbles and is released into the atmosphere.

[0037] In the concrete sludge treatment apparatus 100, the carbon dioxide gas introducing means 30 and the organic component decomposing means 50 are operated simultaneously, whereby the decomposition of the admixture and the production of calcium carbonate can be carried out simultaneously.

[0038] In addition, in the concrete sludge treatment device 100, the carbon dioxide gas introducing means 30 may be operated after the organic component decomposing means 50 has been operated to sufficiently separate the admixture from the surfaces of the cement particles. In this case, it is possible to further reduce the amount of admixture mixed in the recovered calcium carbonate.

[0039] Whether the admixtures in the concrete sludge have been sufficiently removed can be determined by analyzing the components of the remaining concrete sludge. Therefore, the means 60 to 80 of the organic component decomposition means 50 should be operated so that the admixtures in the concrete sludge are sufficiently decomposed.

[0040] Although not shown, an outlet may be provided at the bottom of the treatment tank 10, and precipitated calcium carbonate may be collected from this outlet. This allows concrete sludge to be continuously supplied into the treatment tank 10 and treated continuously. Furthermore, aggregates and the like may be collected from the outlet.

[0041] A concrete sludge treatment apparatus 200 according to a second embodiment of the present invention will be described below with reference to Fig. 2. The concrete sludge treatment apparatus 200 has a common configuration with the concrete sludge treatment apparatus 100, and therefore a description of the common configuration will be omitted.

[0042] The concrete sludge treatment device 200 includes a first treatment tank 110, a second treatment tank 120, a sludge introducing means 20, a carbon dioxide gas introducing means 30, a first stirring means 130, a second stirring means 140, and an organic component decomposition means 50.

[0043] Water is stored inside the first treatment tank 110. Although not shown, water may be supplied from outside into the first treatment tank 110 by a water supply means such as a pump. Concrete sludge is introduced into the bottom of the first treatment tank 110 via sludge introduction means 20. Organic components in the contents contained in the first treatment tank 110 are decomposed by organic component decomposition means 50.

[0044] The second treatment tank 120 stores the contents that have overflowed from the top of the first treatment tank 110. Carbon dioxide gas is introduced into the bottom of the first treatment tank 120 via carbon dioxide gas introduction means 30. Although not shown, the treated water in the second treatment tank 120 may be discharged to the outside by water discharge means such as a pump.

[0045] The first stirring means 130 suitably stirs the contents contained in the first treatment tank 110. The second stirring means 140 suitably stirs the contents contained in the second treatment tank 120. The first and second stirring means 130, 140 have the same configuration as the stirring means 40 described above.

[0046] In the concrete sludge treatment apparatus 200 described above, concrete sludge is introduced from the sludge introducing means 20 into water contained in the first treatment tank 110, and the concrete sludge is turned into a slurry by being stirred by the first stirring means 130. Then, the admixtures adsorbed to the surfaces of the cement particles in the slurried concrete sludge are decomposed by the organic component decomposition means 50. As a result, the admixtures on the surfaces of the cement particles are decomposed and removed, making it easier for the calcium components of the cement particles to dissolve into the water. The admixtures mixed in the concrete sludge are released into the water and decomposed by the organic component decomposition means 50.

[0047] The admixture is decomposed into water, carbon dioxide gas, oxygen gas, nitrogen gas, etc. by the organic component decomposition means 50. The water generated by the decomposition is mixed with the water already in the first treatment tank 110. The carbon dioxide gas generated by the decomposition reacts with the eluted calcium component to produce calcium carbonate, which accumulates at the bottom of the first treatment tank 110. This calcium carbonate that accumulates at the bottom is allowed to settle and recovered. The remaining carbon dioxide gas then rises as bubbles and is released into the atmosphere. The oxygen gas and nitrogen gas also rise as bubbles and are released into the atmosphere.

[0048] The contents of the first treatment tank 110 that overflow from the top of the first treatment tank 110 are then stored in the second treatment tank 120. Carbon dioxide gas is introduced into this second treatment tank 120 from the carbon dioxide gas introduction means 30, which also causes the calcium components that have dissolved into the water from the surfaces of the cement particles to react with the carbon dioxide to produce calcium carbonate, which accumulates in the lower part of the second treatment tank 120. The calcium carbonate that accumulates in the lower part is then precipitated and recovered. Since the admixtures are decomposed by the organic component decomposition means 50, only a small amount of admixture is mixed in with the recovered calcium carbonate. The remaining carbon dioxide gas rises as bubbles and is released into the atmosphere.

[0049] In the concrete sludge treatment apparatus 200, after the admixture is separated from the surface of the cement particles by the organic component decomposition means 50 in the first treatment tank 110, carbon dioxide gas is introduced by the carbon dioxide gas introduction means 30 in the second treatment tank 120. This makes it possible to effectively reduce the amount of admixture mixed in with the recovered calcium carbonate.

[0050] Although not shown, discharge ports may be provided at the bottom of the first and second treatment tanks 110, 120, and precipitated calcium carbonate may be collected from these discharge ports. This allows concrete sludge to be continuously supplied to the first treatment tank 110 and treated continuously.

[0051] The present invention is not limited to the concrete sludge treatment devices 100, 200 specifically described in the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0052] For example, the concrete sludge treatment apparatuses 100, 200 may not be equipped with the agitation means 40, 130, 140. Furthermore, the concrete sludge treatment apparatuses 100, 200 may not be equipped with the sludge introducing means 20, and an operator or the like may put the concrete sludge into the treatment tank 10 or the first treatment tank 110. Furthermore, in the concrete sludge treatment apparatus 200, the contents in the first treatment tank 110 are transferred to the second treatment tank 120 by overflowing the first treatment tank 110, but the manner of transfer is not limited to this. For example, the transfer may be performed using a pump or the like. [Explanation of symbols]

[0053] 10...treatment tank, 20...sludge introduction means, 30...carbon dioxide gas introduction means, 31...disperser, 40...agitation means, 50...organic component decomposition means, 60...ozone gas introduction means, 61...disperser, 70...hydrogen peroxide introduction means, 80...ultraviolet light irradiation means, 100, 200...concrete sludge treatment device, 110...first treatment tank, 120...second treatment tank, 130...first agitation means, 140...second agitation means.

Claims

1. a treatment tank for containing concrete sludge and water; an organic component decomposition means for decomposing organic components contained in the concrete sludge contained in the treatment tank; a carbon dioxide gas introducing means for introducing carbon dioxide gas into the treatment tank.

2. a first treatment tank containing concrete sludge and water; an organic component decomposition means for decomposing organic components contained in the concrete sludge contained in the first treatment tank; a second treatment tank into which the contents of the first treatment tank are transferred; a carbon dioxide gas introducing means for supplying carbon dioxide gas into the second treatment tank.

3. 3. The concrete sludge treatment apparatus according to claim 1, wherein the organic component decomposition means is a means for introducing ozone into the treatment tank or the first treatment tank.

4. 3. The concrete sludge treatment apparatus according to claim 1, wherein the organic component decomposition means is a means for introducing hydrogen peroxide into the treatment tank or the first treatment tank.

5. 3. The concrete sludge treatment apparatus according to claim 1, wherein the organic component decomposition means is a means for irradiating the inside of the treatment tank or the first treatment tank with ultraviolet light.

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