A device and method for high-efficiency carbonation of recycled concrete aggregate based on solution circulation seepage

Abstract

The application discloses a kind of based on solution circulation percolation's recycled concrete aggregate high-efficiency carbonation device and carbonation method, the device is sequentially provided with carbon dioxide gas supply system, liquid storage tank, micro-nano bubble carbonated water generating system, atomizing spray system, storage reaction system along the flow direction of aqueous solution.The application utilizes the based on solution circulation percolation's recycled concrete aggregate high-efficiency carbonation device to carry out carbonation, including: after drying recycled concrete aggregate is evenly filled into storage reaction system, while pouring aqueous solution in liquid storage tank;Carbon dioxide gas is introduced by opening carbon dioxide gas supply system, micro-nano bubble carbonated water generating system is started to the recycled concrete aggregate sustained carbonation, during maintaining the supply of carbon dioxide gas and the circulation of aqueous solution, i.e., recycled concrete aggregate after carbonation can be obtained.The application provides a new method for large-scale carbonation treatment of recycled concrete aggregate, which has low cost, high efficiency and convenient implementation, and has practical engineering application potential.

Description

Technical Field

[0001] This invention relates to a high-efficiency carbonation device and method for recycled concrete aggregate based on solution circulation and seepage, belonging to the field of solid waste treatment, disposal and resource utilization. Background Technology

[0002] In recent years, accelerated carbonation has gained increasing attention in the field of recycled concrete aggregate (RCA) modification. Carbon dioxide can react with hydration products in old mortar to generate carbonation products such as calcium carbonate and amorphous silica gel, resulting in volume expansion. This effectively fills weak points in the old mortar, such as pores, microcracks, and interfacial transition zones, thereby enhancing the performance of RCA. Furthermore, RCA also acts as a carrier to immobilize carbon dioxide, making it environmentally friendly.

[0003] Depending on the moisture conditions, existing RCA accelerated carbonization technologies can be divided into semi-dry carbonization and wet carbonization. Semi-dry carbonization requires precise control of carbonization process parameters (such as pressure, relative humidity, carbon dioxide concentration, and temperature) to achieve a high degree of carbonization in a short time. Its carbonization scale is limited by the size of the carbonization equipment, making it unsuitable for practical engineering applications. Wet carbonization provides a sufficient solution environment for phase dissolution (the mass of water is generally 10 times or more of the mass of RCA), and its dependence on carbonization equipment is less, making it more potential for large-scale application. However, its high water consumption also presents challenges for practical engineering applications. On the one hand, providing 10 times the mass of water and configuring suitable reaction vessels becomes difficult when carbonizing RCA on a large scale; on the other hand, excessively high solution mass is not conducive to achieving the baseline reaction concentration of solute, and it also increases the waste of residual solute in the solution after the reaction, reducing carbonization efficiency and material utilization efficiency. Therefore, it is imperative to develop a low-cost, high-efficiency RCA carbonization method suitable for practical engineering applications. Summary of the Invention

[0004] Purpose of the invention: One objective of this invention is to provide a high-efficiency carbonation device for recycled concrete aggregate based on solution circulation and seepage. Another objective of this invention is to provide a method for carbonation of recycled concrete aggregate using this device, thereby solving the problem that existing carbonation technologies are not suitable for large-scale applications and achieving performance enhancement of recycled concrete aggregate and permanent CO2 sequestration.

[0005] Technical Solution: The present invention discloses a high-efficiency carbonation device for recycled concrete aggregate based on solution circulation and seepage. Along the flow direction of the aqueous solution, a carbon dioxide supply system, a storage tank, a micro / nano bubble carbonated water generation system, an atomizing spray system, and a storage reaction system are sequentially arranged. The micro / nano bubble carbonated water generation system is connected to the carbon dioxide supply system, the storage tank, and the atomizing spray system via pipelines. The atomizing spray system is located at the top of the storage reaction system, and the storage tank is located at the bottom of the storage reaction system.

[0006] Furthermore, the carbon dioxide supply system includes a carbon dioxide source, which is connected to the nanobubble carbonated water generation system via pipelines. The micro-nanobubble carbonated water generation system includes a micro-nanobubble generator, which is connected to the carbon dioxide supply system, the atomizing spray system, and the storage tank via pipelines. The storage and reaction system includes a silo, with a grid plate on the upper part of the silo bottom plate, a stainless steel filter screen on the upper part of the grid plate, an atomizing spray system located at the top of the silo and fixed to the inner wall of the silo by pipe clamps, and a storage tank located at the bottom of the silo. The silo bottom plate has a permeable zone, and the storage tank is located below the permeable zone.

[0007] Furthermore, the silo is a cylindrical silo with a height 2.5-3.0 times its inner diameter. The diameter of the permeable zone is 0.3-0.5 times its inner diameter. The permeable zone has a large number of evenly distributed circular openings with a diameter 0.02-0.04 times its inner diameter. The top of the silo is hollow and can be used for filling and removing recycled concrete aggregate. The bottom of the silo is equipped with multiple support legs, generally more than three.

[0008] The present invention discloses a method for carbonating recycled concrete aggregate using a high-efficiency carbonation device based on solution circulation and seepage, comprising the following steps:

[0009] (1) The recycled concrete aggregate is evenly filled into the upper part of the stainless steel filter screen (8) in the silo (7), and water is added to the liquid storage tank (1);

[0010] (2) Open the valve of the carbon dioxide gas source (11) to introduce carbon dioxide gas;

[0011] (3) Start the micro-nano bubble generator (4), set the water flow rate, and perform carbonization.

[0012] Further, in step (1), the recycled concrete aggregate is obtained by crushing and screening waste concrete. The particle size of the recycled concrete aggregate is 0.075-4.75 mm, and the filling height of the recycled concrete aggregate is 0.6-1.5 times the inner diameter of the silo 7. The mass of water in the storage tank (1) is 0.5-0.8 times that of the recycled concrete aggregate. In step (2), the volume fraction of carbon dioxide gas in the carbon dioxide gas source (11) is 30-100%, and the flow rate of carbon dioxide gas is 0.15-0.3 L / min / kg of recycled concrete aggregate (i.e., the carbon dioxide gas introduced per kilogram of recycled concrete aggregate is controlled at 0.15-0.3 L per minute). In step (3), the diameter of the micro-nano carbon dioxide bubbles formed in the micro-nano bubble generator (4) is 90nm-40μm. In step (3), the water flow rate is 0.3-0.6L / min / kg recycled concrete aggregate (i.e., the flow rate of the aqueous solution is controlled at 0.3-0.6L per minute per kilogram of recycled concrete aggregate), and the carbonation time is 2-6h.

[0013] The technical principle of this invention is:

[0014] Traditional wet carbonation typically involves immersing recycled concrete aggregate in a large amount of aqueous solution (the water mass is generally 10 times or more of the RCA mass), followed by introducing carbon dioxide gas to initiate the carbonation reaction. This invention innovatively proposes a circulating, seepage-flow method through the recycled concrete aggregate, significantly reducing the amount of aqueous solution used (the water mass is only 0.5-0.8 times the RCA mass). Furthermore, the reduced solution mass makes it easier for the solute to reach the baseline reaction concentration, improving solute reaction and transport efficiency and accelerating the carbonation process of the recycled concrete aggregate. In addition, because the carbonated water in this invention flows through the recycled concrete aggregate in a seepage-flow manner, the carbonated water reacts with the hydration products within the aggregate, resulting in a greater proportion of carbonation products being generated through in-situ deposition. By limiting the ion migration range after the hydration products dissolve, the problem of micropores formed by the dissolution of hydration products without in-situ filling by the carbonation products is avoided.

[0015] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The water requirement of traditional wet carbonization is greater than or equal to 10 times the aggregate mass. The present invention recycles the aqueous solution, and the water requirement is only 0.5-0.8 times the aggregate mass. When carbonizing recycled concrete aggregate on a large scale, the present invention solves the problem that traditional wet carbonization requires a large-volume reaction vessel, and is easier to implement and lower in cost than traditional wet carbonization. (2) The water requirement of the present invention is only 0.5-0.8 times the aggregate mass. The reduction in solution mass allows the solute (calcium ions, carbonate ions) to reach the baseline reaction concentration faster, while reducing the waste of residual solute in the solution after the reaction, and improving carbonization efficiency and material utilization efficiency. (3) Compared with traditional wet carbonization, the carbonization products in the present invention are generated more in situ in the form of deposition, which is more conducive to filling the pores, microcracks and interface transition zones in old mortar in situ, thereby enhancing the performance of RCA technology.

[0016] In summary, the technical solution proposed in this invention provides a new, low-cost, efficient, and easy-to-implement method for large-scale carbonization treatment of recycled concrete aggregates, with potential for practical engineering applications. It effectively promotes the resource utilization of waste concrete and achieves permanent CO2 sequestration, resulting in significant environmental and economic benefits. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the high-efficiency carbonation device for recycled concrete aggregate based on solution circulation flow according to the present invention.

[0018] Figure 2 This is a schematic diagram of the base plate of the material storage and reaction system of the present invention;

[0019] In the diagram: 1. Storage tank; 2. Aqueous solution; 3. Inlet pipe; 4. Micro / nano bubble generator; 5. Outlet pipe; 6. Atomizing spray system; 7. Cylindrical silo; 8. 200-mesh stainless steel filter screen; 9. Grating plate; 10. Permeable zone; 11. Carbon dioxide gas source; 12. Inlet pipe; 13. Micro / nano bubble carbonated water generation system; 14. Material storage and reaction system; 15. Carbon dioxide supply system.

[0020] Figure 3 This is a schematic diagram of the structure of a conventional wet carbonization device in the prior art. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0022] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] The raw materials and properties are as follows:

[0024] Recycled concrete aggregate (RCA): Derived from the concrete pavement layer of a road project in Nanjing, it is obtained through crushing and screening, with a particle size range of 0.075–4.75 mm, and is referred to as recycled concrete fine aggregate. According to the standard "Construction Sand" (GB / T14684-2022), the apparent density, water absorption rate, and crushing index of RCA were measured to be 2495 kg / m³. 3 27.5% and 14.01%.

[0025] Carbon dioxide gas source: Carbon dioxide gas with a purity of 99.3% produced by a gas company in Nanjing.

[0026] Aqueous solution: Tap water in Nanjing area.

[0027] Example 1

[0028] like Figure 1-2As shown, the present invention discloses a high-efficiency carbonation device for recycled concrete aggregate based on solution circulation and seepage. Along the flow direction of the aqueous solution, it is sequentially equipped with a carbon dioxide supply system 15, a storage tank 1, a micro / nano bubble carbonated water generation system 13, an atomizing spray system 6, and a storage reaction system 14. The carbon dioxide supply system 15 includes a carbon dioxide source 11 connected to an inlet pipe 12. The micro / nano bubble carbonated water generation system 13 includes a micro / nano bubble generator 4 connected to an inlet pipe 3 and an outlet pipe 5. The micro / nano bubble generator 4 is connected to the storage tank 1 via the inlet pipe 13 and to the carbon dioxide source 11 via the inlet pipe 12. The material storage and reaction system 14 includes a cylindrical silo 7. A grating plate 9 is laid on the bottom plate of the cylindrical silo 7, covering the entire bottom area of ​​the silo 7. The grating plate 9 is a commonly used industrial grating plate. A 200-mesh stainless steel filter screen 8 is laid on top of the grating plate 9, covering the entire area of ​​the grating plate 9. An atomizing spray system 6 is installed on the top of the cylindrical silo 7, and the atomizing spray system 6 is fixed to the inner wall of the cylindrical silo 7 by pipe clamps. A micro-nano bubble generator 4 is connected to the atomizing spray system 6 through a liquid outlet pipe 5. Four support legs are provided under the bottom plate of the cylindrical silo 7. The size and specifications of the support legs are customized according to project requirements, ensuring that the load-bearing capacity meets the working requirements and that the bottom space of the cylindrical silo 7 can accommodate the liquid storage tank 1. The cylindrical silo 7 has an inner diameter of d and a height of 2.5-3.0d, with the specific value of d customized according to project requirements. The cylindrical silo 7 is waterproof. The top of the cylindrical silo 7 is open, allowing for the filling and removal of recycled concrete aggregate. A permeable zone 10 is located at the center of the bottom plate of the cylindrical silo 7. The permeable zone 10 is a circle with a diameter ranging from 0.3-0.5d, and a large number of evenly distributed circular openings with a diameter of 0.02-0.04d are located within this zone. A storage tank 1 is positioned below the permeable zone 10.

[0029] Along the flow direction of the aqueous solution, the carbon dioxide supply system 15 and the storage tank 1 respectively input carbon dioxide gas and aqueous solution into the micro-nano bubble carbonated water generation system 14 through the air inlet pipe 12 and the liquid inlet pipe 3, where they fuse to form micro-nano bubble carbonated water; the micro-nano bubble carbonated water is output from the micro-nano bubble carbonated water generation system 13 to the atomizing spray system 6 through the liquid outlet pipe 5; the atomizing spray system 6 sprays the micro-nano bubble carbonated water onto the material storage reaction system 14; the micro-nano bubble carbonated water undergoes a carbonation reaction with the recycled concrete aggregate in the material storage reaction system 14 in the form of seepage, and after the reaction, it naturally flows back to the storage tank 1.

[0030] The method for carbonating recycled concrete aggregate using a high-efficiency carbonation device based on solution circulation and seepage, as described in this invention, includes the following steps:

[0031] (1) Dry or air dry the recycled concrete aggregate. Fill the upper part of the stainless steel filter screen 8 in the silo 7 with the dried recycled concrete aggregate of mass m1 evenly. Add the aqueous solution of mass m2 into the storage tank 1.

[0032] (2) Open the gas valve of carbon dioxide gas source 11 to introduce carbon dioxide gas and set the gas flow rate.

[0033] (3) Start the micro-nano bubble generator 4, set the water flow rate, and perform carbonization.

[0034] In step (1), the mass m1 of the recycled concrete aggregate is determined according to the project requirements, and the filling height of the recycled concrete aggregate in the silo is controlled to be 0.6-1.5 times the inner diameter d of the silo 7. The mass m2 of the water in the storage tank (1) is 0.5-0.8 m1. In step (2), the volume fraction of carbon dioxide gas in the carbon dioxide gas source (11) is 30-100%, and the flow rate of carbon dioxide gas is 0.15-0.3 L / min / kg recycled concrete aggregate (i.e., the carbon dioxide gas introduced per kilogram of recycled concrete aggregate is controlled at 0.15-0.3 L / min). In step (3), the diameter of the micro-nano carbon dioxide bubbles formed in the micro-nano bubble generator (4) is 90 nm-40 μm, the flow rate of water is 0.3-0.6 L / min / kg recycled concrete aggregate (i.e., the flow rate of the aqueous solution per kilogram of recycled concrete aggregate is controlled at 0.3-0.6 L / min), and the carbonation time is 2-6 h.

[0035] Example 2

[0036] Carbonation was carried out using the efficient carbonation device and method for recycled concrete aggregate based on solution circulation infiltration as described in Example 1, with the following parameter settings:

[0037] The liquid storage tank 1 uses a 2000mL beaker; the micro-nano bubble generator 4 is a research-grade micro-nano bubble generator manufactured by NANOscientific, which generates micro-nano carbon dioxide bubbles with a diameter range of approximately 90nm-40μm, a maximum flow rate of 1.5L / min, and a self-priming height of 0.8m; the atomizing spray device 6 uses a 6mm copper spray head, and there is one device; the cylindrical silo 7 is made of acrylic material, with an inner diameter of 20cm and a height of 50cm; the diameter of the water permeable zone 10 is 6cm, the diameter of the water permeable holes is 4mm, the grid plate 9 is a plastic grid plate, and the stainless steel filter 8 uses a 200-mesh stainless steel filter.

[0038] The operation is as follows:

[0039] S1: Weigh 3 kg of dried recycled concrete fine aggregate and fill it evenly into the cylindrical silo 7. The filling height of the recycled concrete fine aggregate in the cylindrical silo 7 is about 15 cm.

[0040] S2: Weigh 1.8 kg of the aqueous solution and pour it into storage tank 1;

[0041] S3: Open the valve of carbon dioxide gas source 11 to introduce carbon dioxide gas, and set the ventilation rate to 0.15L / min;

[0042] S4: Start the micro / nano bubble generator 4 and set the aqueous solution flow rate to 0.9 L / min;

[0043] S5: Carbonize the recycled concrete aggregate continuously for 2 hours, while maintaining the supply of carbon dioxide gas and the circulation of the aqueous solution, and finally obtain the carbonized recycled concrete aggregate RCA-S1.

[0044] Performance testing:

[0045] The apparent density, water absorption rate and crushing index parameters of RCA-S1 were tested according to the "Construction Sand" (GB / T 14684-2022), and the results are shown in Table 1.

[0046] Example 3

[0047] The experimental procedure is the same as in Example 2, except that the carbonation time in step S5 is replaced by 6 hours instead of 2 hours, resulting in carbonated recycled concrete aggregate RCA-S2. Specific implementation steps:

[0048] The apparent density, water absorption rate, and crushing index parameters of RCA-S2 were tested in the same manner as in Example 2, and the results are shown in Table 1.

[0049] Example 4

[0050] The experimental procedure is the same as in Example 2, except that air (with a carbon dioxide concentration of approximately 0.04%) is used directly in step S3 to obtain carbonized recycled concrete aggregate RCA-S3. Specific implementation steps:

[0051] The apparent density, water absorption rate, and crushing index parameters of RCA-S3 were tested in the same manner as in Example 2, and the results are shown in Table 1.

[0052] Example 5

[0053] The experimental procedure was the same as in Example 2, except that the aeration rate in step S3 was changed from 0.15 L / min to 0.05 L / min, resulting in carbonized recycled concrete aggregate RCA-S4. Specific implementation steps:

[0054] The apparent density, water absorption rate, and crushing index parameters of RCA-S4 were tested in the same manner as in Example 2, and the results are shown in Table 1.

[0055] Example 6

[0056] The experimental procedure was the same as in Example 2, except that the mass of the aqueous solution in step S2 was replaced with 1.2 kg instead of 1.8 kg. The solution could not complete the circulation, and the device failed to operate.

[0057] Comparative Example 1:

[0058] Carbonizing recycled aggregates using conventional carbonization equipment, such as Figure 3 As shown, the specific parameters of a typical carbonization device are as follows:

[0059] The reaction vessel is a 50L polyethylene plastic bucket; the stirring device is a steering wheel stirrer with a speed of 0-850 rpm; the mesh cage is a stainless steel wire frame with a 200-mesh stainless steel filter screen at the bottom for placing recycled concrete aggregate. Since the micro-nano bubble generator can increase the solubility of carbon dioxide in aqueous solution, it helps to accelerate the carbonization process. To more scientifically compare the effects of this invention with ordinary carbonization devices, the carbon dioxide supply method of the ordinary carbonization device was synchronized with that of this invention, but it was changed to the micro-nano bubble carbonated water generation system of this invention, while other settings remained unchanged.

[0060] Specific implementation steps:

[0061] S1: Weigh 3 kg of dried recycled concrete fine aggregate and fill it evenly into the mesh cage. Weigh 30 kg of aqueous solution and pour it into the reaction vessel. Then, immerse the mesh cage completely in the aqueous solution.

[0062] S2: Start the agitator, set the agitation speed to 200 r / min, open the gas valve of the carbon dioxide supply system to introduce carbon dioxide gas, and set the gas flow rate to 0.15 L / min;

[0063] S3: Start the micro / nano bubble generator and set the aqueous solution flow rate to 0.9 L / min;

[0064] S4: Carbonize the recycled concrete aggregate continuously for 2 hours while maintaining the supply of carbon dioxide gas, and finally obtain the carbonized recycled concrete aggregate RCA-D1.

[0065] The apparent density, water absorption rate, and crushing index parameters of RCA-D1 were tested in the same manner as in Example 2, and the results are shown in Table 1.

[0066] Comparative Example 2:

[0067] The experimental procedure was the same as that of Comparative Example 1, except that the carbonation time in step S4 was replaced by 6 hours instead of 2 hours, resulting in carbonized recycled concrete aggregate RCA-D2.

[0068] The apparent density, water absorption rate, and crushing index parameters of RCA-D2 were tested in the same manner as in Example 2, and the results are shown in Table 1.

[0069] Table 1 Comparison of technical performance indicators of recycled aggregate before and after carbonization

[0070]

[0071]

[0072] As shown in Table 1, the technical performance of the recycled concrete aggregates in Examples 2 and 3, as well as Comparative Examples 1 and 2, was improved after carbonation treatment, manifested as increased apparent density and decreased crushing index and water absorption. Comparing Example 2 and Comparative Example 1, it can be found that under the same carbonation time and carbon dioxide supply conditions, RCA-S1 performed significantly better than RCA-D1, indicating that Example 2 had a better carbonation effect than Comparative Example 1. Similar results were also verified in Example 3 and Comparative Example 2. Furthermore, comparing Examples 2 and 3, and Comparative Examples 1 and 2, it can be found that increasing the carbonation time is beneficial to improving the carbonation effect. This is mainly because insufficient carbonation time leads to incomplete carbonation reaction and a smaller amount of carbonation products. In terms of the degree of improvement in carbonation effect, Example 2 only carbonized for 2 hours, but its effect on improving aggregate performance was better than that of Comparative Example 2, which carbonized for 6 hours. This indicates that the present invention achieves a higher degree of carbonation in the recycled aggregate in a shorter time. Comparing Examples 2, 4, and 5, it is evident that the carbonization effect deteriorates when a low concentration of carbon dioxide is used or the carbon dioxide aeration rate is reduced. This is related to the reduced supply of carbon dioxide, which affects the carbonization reaction.

[0073] The data results from the examples and comparative examples further verify the practicality of the present invention. The carbonization effect and carbonization efficiency of the present invention are superior to those of ordinary carbonization methods, and it has higher material utilization efficiency.

[0074] The present invention has been disclosed above with reference to preferred embodiments, but it is not intended to limit the present invention. All technical solutions obtained by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the present invention.

Claims

1. A high-efficiency carbonation device for recycled concrete aggregate based on solution circulation and seepage, characterized in that, Along the flow direction of the aqueous solution, a carbon dioxide supply system (15), a storage tank (1), a micro-nano bubble carbonated water generation system (13), an atomizing spray system (6), and a storage reaction system (14) are arranged in sequence. The micro-nano bubble carbonated water generation system (13) is connected to the carbon dioxide supply system (15), the storage tank (1), and the atomizing spray system (6) through pipes. The atomizing spray system (6) is located at the top of the storage reaction system (14), and the storage tank (1) is located at the bottom of the storage reaction system (14). The storage reaction system (14) includes a silo (7). A grid plate (9) is provided on the upper part of the bottom plate of the silo (7), and a stainless steel filter screen (8) is provided on the upper part of the grid plate (9). The atomizing spray system (6) is located at the top of the silo (7), and the storage tank (1) is located at the bottom of the silo (7). The bottom plate of the silo (7) is provided with a permeable area (10), and the storage tank (1) is located below the permeable area (10).

2. The high-efficiency carbonation device for recycled concrete aggregate according to claim 1, characterized in that, The carbon dioxide supply system (15) includes a carbon dioxide source (11), which is connected to the micro-nano bubble carbonated water generation system (13) through a pipeline.

3. The high-efficiency carbonation device for recycled concrete aggregate according to claim 1, characterized in that, The micro-nano bubble carbonated water generation system (13) includes a micro-nano bubble generator (4), which is connected to a carbon dioxide supply system (15), an atomizing spray system (6), and a storage tank (1) via pipes.

4. The high-efficiency carbonation device for recycled concrete aggregate according to claim 1, characterized in that, The silo (7) is a cylindrical silo. The height of the silo (7) is 2.5-3.0 times the inner diameter of the silo (7). The diameter of the permeable zone (10) is 0.3-0.5 times the inner diameter of the silo (7). A large number of circular openings are evenly distributed in the permeable zone (10), and the diameter of the openings is 0.02-0.04 times the inner diameter of the silo (7). ， The top of the silo (7) is hollowed out, and multiple support legs are provided at the bottom of the silo (7).

5. A method for carbonizing recycled concrete aggregate using the high-efficiency carbonation device for recycled concrete aggregate based on solution circulation seepage as described in any one of claims 1-4, comprising the following steps: (1) The recycled concrete aggregate is evenly filled into the upper part of the stainless steel filter screen (8) in the silo (7), and water is added to the storage tank (1); (2) Turn on the carbon dioxide gas source (11) and introduce carbon dioxide gas; (3) Start the micro-nano bubble generator (4), set the water flow rate, and perform carbonization.

6. The method according to claim 5, characterized in that, In step (1), the particle size of the recycled concrete aggregate is 0.075-4.75 mm, and the filling height of the recycled concrete aggregate is 0.6-1.5 times the inner diameter of the silo (7); the mass of the water in the storage tank (1) is 0.5-0.8 times the recycled concrete aggregate.

7. The method according to claim 5, characterized in that, In step (3), the diameter of the micro-nano carbon dioxide bubbles formed in the micro-nano bubble generator (4) is 90 nm-40 μm. In step (3), the water flow rate is 0.3-0.6 L / min / kg recycled concrete aggregate, and the carbonation time is 2-6 h.

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