Fluidization reaction device and method for efficiently mineralizing carbon dioxide by using solid waste

Abstract

The invention belongs to the technical field of carbon sequestration, and particularly relates to a fluidization reaction device and method for efficiently mineralizing carbon dioxide by solid waste, and the method comprises the following steps: pretreating the solid waste to obtain solid waste powder; the method comprises the following steps: atomizing an alkaline solvent into water mist, inputting CO2 gas and the water mist into a fluidized bed reactor by utilizing a fan, and adding solid waste powder into the fluidized bed reactor; the mass ratio of the water mist and the solid waste powder entering the fluidized bed reactor and the gas flow speed of the CO2 gas and the water mist are adjusted, gas-liquid-solid three-phase fluidization is conducted on the solid waste powder in the fluidized bed reactor under driving of the gas phase of the CO2 gas, and mineralization reaction is conducted; after full reaction, discharging solid waste powder by using a rotary discharging device, and drying the solid waste powder to constant weight by using a constant-temperature drying box to obtain an auxiliary cementing material; according to the method, the contact efficiency and the mass transfer rate of the solid waste and CO2 can be improved, the solid waste can quickly react with CO2 gas in the fluidized bed reactor, the reaction time is remarkably shortened, and the low cost and the high efficiency of the CO2 mineralization reaction of the solid waste powder are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon sequestration, and in particular relates to a fluidized reaction device and method for efficiently mineralizing carbon dioxide from solid waste. Background Art

[0002] With the release of the "Special Action Plan for Energy Conservation and Carbon Reduction in the Steel Industry", carbon emission reduction and solid waste (referred to as "solid waste") management have become the focus of attention of enterprises. More importantly, due to the high activity of cations such as alkaline earth metals in solid wastes such as steel slag and refined slag, it is very easy to cause premature cement hardening and aggregation, which will cause poor stability problems such as expansion and cracking of building materials. For example, GB175-2023 "General Portland Cement" released in 2023 did not include solid wastes such as steel slag in the mixed materials of Portland cement, resulting in restrictions on the large-scale disposal of such solid wastes. Studies have found that by treating alkaline solid waste powders with CO2 mineralization technology, cations such as alkaline earth metals in solid wastes can be converted into stable neutral carbonates, achieving "carbon fixation and alkali reduction" of solid wastes and preparing auxiliary cementitious materials for cement or concrete. CO2 mineralization of solid waste has the advantages of strong environmental friendliness, green and low carbon, and has gradually become an emerging technology for large-scale CO2 emission reduction and comprehensive utilization of solid wastes.

[0003] In the process of CO2 mineralization of solid waste, the choice of reactor is crucial and will directly affect the CO2 absorption efficiency, process safety and process economy. Many researchers have tried to apply a variety of reactors (high-pressure reactors, rotating packed beds, tubular reactors, bubbling beds, etc.) to the CO2 reaction process of solid waste powder mineralization. Among them, the kettle reactor has the characteristics of simple structure, convenient operation and mature technology. It is widely used in the mineralization and maintenance process of solid waste-based building materials, and has been successfully verified in 10,000-ton industrial demonstrations. However, due to the slow mass transfer-reaction rate of CO2 mineralization, it often requires a long reaction and maintenance time. Although most studies have promoted the mass transfer rate through high temperature or high pressure methods, this requires a lot of energy consumption, resulting in high technical costs, which is not conducive to further engineering amplification and promotion. Based on this, developing a method that can significantly improve the efficiency of solid waste absorption-mineralization of CO2 for the CO2 mineralization of solid waste process is the key to improving the economy of the reaction process. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a fluidized reaction device and method for the efficient mineralization of carbon dioxide from solid waste, which solves the problem of insufficient contact between solid waste and CO2 in the existing reactor, leading to slow mass transfer-reaction rate, long reaction time and high technical cost.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A fluidized reaction method for efficiently mineralizing carbon dioxide from solid waste is provided, comprising the following steps:

[0007] S1: solid waste pretreatment: pretreating the solid waste particles to obtain solid waste powder with a particle size of less than 100 μm;

[0008] S2: Construction of fluidized system: The mixed solution containing alkaline solvent is atomized by an atomizer to obtain water mist, the mixture of CO2 gas and water mist is input into the fluidized bed reactor from the gas inlet by a fan, and solid waste powder is added into the fluidized bed reactor through the feed inlet;

[0009] S3: Solid waste mineralization reaction: water mist and solid waste powder with a mass ratio of 0.2 to 0.5 are input into the fluidized bed reactor, and the gas flow rate of the mixture of CO2 gas and water mist is adjusted. The mixture of CO2 gas and water mist is evenly distributed through the gas distribution plate and then flows upward in the fluidized reactor. Driven by the gas phase of CO2 gas, the solid waste powder undergoes gas-liquid-solid three-phase fluidization in the reaction chamber of the fluidized bed reactor. The solid waste powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0010] S4: Post-reaction treatment: After the mineralization reaction is fully completed, the solid waste powder after the reaction is discharged from the fluidized bed reactor by a rotary discharger, and the auxiliary cementitious material is obtained after being dried to a constant weight in a constant temperature drying oven.

[0011] The beneficial effects of adopting the above technical scheme are as follows: the pretreatment operations such as crushing and ball milling in step S1 can refine the particle size of solid waste particles, increase the specific surface area of ​​solid waste particles, and then improve the contact efficiency between solid waste particles and CO2 and water mist, which is conducive to achieving a more stable gas-liquid-solid three-phase fluidization state in the fluidized bed reactor, thereby accelerating the mineralization reaction rate; in step S2, the mixed liquid containing alkaline solvent is first atomized by an atomizer to obtain water mist, which can make the water mist solvent be evenly dispersed in the CO2 gas to form a gas-liquid mixture, and then the mixture of CO2 gas and water mist is input into the fluidized bed reactor by a fan. In the fluidized bed reactor, a stable airflow is provided for the fluidized bed reactor, which is conducive to achieving the fluidized state of the solid waste. Then, by adding solid waste powder into the fluidized bed reactor, the solid waste powder can be fluidized under the drive of CO2, which is conducive to the subsequent mineralization reaction. In step S3, the CO2 gas carrying water mist drives the solid waste powder to fluidize. During the fluidization process, after the solid waste powder collides with the water mist droplets, a gas-solid / gas-liquid-solid reaction interface coexists on the surface. The introduction of the liquid phase can reduce the driving force of gas-solid mass transfer. At the same time, the liquid-retaining solid waste powder undergoes non-steady-state fluidization under the drive of CO2 gas, which can Enhance the mixing characteristics of solid waste powder and the reaction contact efficiency, promote the renewal of mass transfer-reaction interface, and under the dual effects of the two, the absorption-mineralization efficiency of flue gas CO2 by solid waste can be significantly improved; and the mass ratio of water mist and solid waste powder entering the fluidized bed reactor is the mass ratio of water mist and solid waste powder entering the fluidized bed reactor. By controlling the mass ratio of water mist and solid waste powder entering the fluidized bed reactor (i.e., liquid-solid ratio) within 0.2-0.5, not only can the solid waste powder be fully wetted and the mass transfer rate between CO2 and solid waste powder be increased; but also the gas-liquid-solid reaction in the fluidized bed reactor can be controlled. Three-phase fluidization is conducive to the full contact between solid waste powder and CO2 and water mist, promotes the mineralization reaction, and then accelerates the reaction rate, converts cations such as alkaline earth metals in the solid waste into stable carbonates, and realizes the "carbon fixation and alkali reduction" of solid waste; in step S4, after the mineralization reaction is fully reacted, the reacted solid waste powder is discharged from the fluidized bed reactor by a rotary discharger, which can realize continuous production and improve production efficiency. After the discharged solid waste powder is dried to constant weight in a constant temperature drying oven, an auxiliary cementitious material can be obtained, which can replace part of the cement cementitious material and has better environmental friendliness.

[0012] This fluidized reaction method introduces water mist to form gas-liquid-solid three-phase fluidization, which effectively improves the contact efficiency between solid waste and CO2, significantly shortens the reaction time, and can achieve continuous loading and unloading of solid waste, avoiding the problem of insufficient gas-solid contact in traditional reactors and the need for intermittent operation.

[0013] Furthermore, the solid waste particles in S1 are alkaline solid waste particles containing calcium oxide or calcium hydroxide.

[0014] The beneficial effects of adopting the above technical scheme are as follows: alkaline solid waste particles containing calcium oxide or calcium hydroxide are easy to undergo mineralization reaction with CO2, and then convert cations such as alkaline earth metals in the alkaline solid waste particles into stable carbonates, thereby achieving "carbon fixation and alkali reduction" of solid waste.

[0015] Furthermore, the mass percentage concentration of CO2 in S2 is ≥10%, and the input temperature of CO2 is 20-30°C.

[0016] The beneficial effects of adopting the above technical solution are: a higher concentration of CO2 can increase the mineralization reaction rate of solid waste powder and CO2, thereby shortening the reaction time and improving production efficiency, while the adapted temperature is conducive to maintaining the chemical stability of the solid waste powder, thereby ensuring the reaction rate.

[0017] Furthermore, the diameter of the water mist obtained after atomization in S2 is 200 to 400 μm.

[0018] The beneficial effects of adopting the above technical solution are: the diameter of the water mist obtained after atomization is 200-400μm, which can be better mixed with CO2 gas and solid waste powder, promote the formation of gas-liquid-solid three-phase fluidization, and facilitate the mineralization reaction to be more complete and efficient.

[0019] Furthermore, the mass fraction of the alkaline solvent in S2 is 5% to 10%, and the pH of the mixed solution is 10 to 12.

[0020] The beneficial effects of adopting the above technical scheme are: the solvent is a mixed solution containing an alkaline solvent, the pH of which is 10-12, and the mass fraction of the alkaline solvent is 5%-10%, which is conducive to the mixing of CO2 in the solvent mist, thereby increasing the mineralization reaction rate of CO2 and solid waste powder. In addition, the alkaline environment can accelerate the reaction of alkaline components in solid waste (such as calcium oxide or calcium hydroxide) with CO2 to generate more stable carbonates.

[0021] Furthermore, the gas flow rate of the mixture of CO2 gas and water mist in S3 is 0.08-0.40 m / s, and the time of the mineralization reaction is 5-20 min.

[0022] The beneficial effects of adopting the above technical scheme are: when the gas velocity of CO2 gas is controlled within the range of 0.08-0.40m / s, it can ensure that the solid waste powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor, and at the same time, the fluidization will not be insufficient due to too low a velocity, nor will the solid waste powder be blown out of the reactor due to too high a velocity, thereby ensuring the effective implementation of the mineralization reaction; and the reaction time of 5-20min can not only ensure the full progress of the reaction, but also effectively shorten the overall process time and improve production efficiency.

[0023] Furthermore, the gas distribution plate in S3 is a hood-type gas distribution plate, the opening rate of which is set to 2% to 4%, and the inclination angle is 0 to 20°.

[0024] The beneficial effects of adopting the above technical solution are as follows: the hood-type gas distribution plate can more effectively disperse and guide the mixture of CO2 gas and water mist into the reaction chamber of the fluidized bed reactor, thereby improving the uniformity of the mixture of CO2 gas and water mist entering the fluidized bed reactor, and facilitating the discharge of solid waste from the bottom of the fluidized bed reactor after the mineralization reaction is completed.

[0025] Furthermore, the drying temperature in S4 is 100-110°C.

[0026] The beneficial effect of adopting the above technical solution is that the solid waste powder after the reaction is dried at a temperature of 100-110° C., which can ensure that the moisture in the solid waste powder is fully removed and avoid the adverse effect of residual moisture on the performance of the auxiliary cementitious material.

[0027] Furthermore, the auxiliary cementitious material in S4 can be used as an admixture of cement or concrete.

[0028] The beneficial effects of adopting the above technical solution are: auxiliary cementitious materials can be used as admixtures for cement or concrete, achieving efficient utilization of solid waste, which can not only reduce the pollution of solid waste to the environment, but also save natural resources and reduce the production cost of cement or concrete.

[0029] To implement the above technical solution, the present invention provides a fluidized reaction device for efficient mineralization of carbon dioxide from solid waste, comprising a fluidized bed reactor, wherein a feed chamber, a reaction chamber and an air inlet chamber are sequentially arranged from top to bottom in the fluidized bed reactor;

[0030] A gas outlet is provided at the top of the feed chamber, and a solid inlet is provided at one side of the bottom of the feed chamber, and the solid inlet is connected to the solid waste bin;

[0031] A gas distribution plate is provided at the connection between the reaction chamber and the gas inlet chamber, a rotary discharger is provided on one side of the gas distribution plate, and the rotary discharger is connected to the solid outlet;

[0032] A gas inlet is provided at the bottom of the air inlet chamber, which is connected to the CO2 delivery device through a pipeline, and the end of the pipeline is connected to the fan for delivering CO2 gas; the middle part of the pipeline is connected to the output end of the atomizer, and the input end of the atomizer is connected to the solvent storage tank for delivering water mist.

[0033] The beneficial effects of adopting the above technical scheme are as follows: the fluidized bed reactor provides space for sufficient mixing and reaction of solid waste powder with CO2 and water mist, realizes effective fluidization of gas, liquid and solid phases, and significantly improves the reaction efficiency; the atomizer can atomize the solvent in the solvent storage tank into tiny droplets, and mix them with CO2 gas before entering the reaction system, providing sufficient moisture for the reaction, and the introduction of water mist not only promotes the mass transfer rate of CO2 to solid waste, but also enhances the mixing characteristics and reaction contact efficiency of solid waste powder; in addition, the gas inlet is connected to the CO2 conveying device through a pipeline and conveyed by a fan, ensuring the stable supply of CO2 gas and the pressure stability of the reaction system, and the fan can improve the mixing effect of gas and solid waste powder and promote the mineralization reaction; The solid waste silo, solid inlet and feed chamber can realize the continuous supply of solid waste powder, so that the solid waste powder can be evenly and stably added to the fluidized reaction system, avoiding the agglomeration and accumulation of solid waste powder, and ensuring the continuity and stability of the reaction; the gas distribution plate is arranged at the connection between the reaction chamber and the air inlet chamber, which can evenly distribute the gas and prevent the blockage and accumulation of solid waste powder. In addition, the porous structure of the gas distribution plate also increases the contact area between the gas and the solid waste powder, thereby promoting the reaction; the rotary discharger can make the reacted solid waste powder be discharged smoothly from the reaction chamber, and can control the discharge rate of the solid waste powder, avoiding the residue and accumulation of solid waste powder, ensuring the completeness and efficiency of the reaction, and can realize the continuous discharge of the reaction products, providing a guarantee for the continuity of the reaction.

[0034] The fluidized reaction device can significantly improve the contact efficiency and reaction rate between solid waste and CO2, achieving low cost and high efficiency of solid waste powder mineralization CO2 reaction.

[0035] In summary, the fluidized reaction device and method for efficient mineralization of carbon dioxide from solid waste provided by the present invention have the following beneficial effects:

[0036] (1) The fluidized reaction method uses CO2 gas carrying water mist to drive the solid waste powder to fluidize. During the fluidization process, after the solid waste powder collides with the water mist droplets, a gas-solid / gas-liquid-solid reaction interface coexists on the surface. The introduction of the liquid phase can reduce the driving force of gas-solid mass transfer. At the same time, the liquid-retaining solid waste powder undergoes non-steady-state fluidization driven by CO2 gas, which will enhance the mixing characteristics and reaction contact efficiency of the solid waste powder and promote the renewal of the mass transfer-reaction interface. Under the dual effects of the two, the absorption-mineralization efficiency of CO2 by the solid waste can be significantly improved, and the reaction time can be greatly shortened.

[0037] (2) This fluidized bed reaction method can achieve efficient absorption of CO2, and can significantly shorten the reaction time while ensuring the absorption efficiency, and reduce the reactor volume at the same processing volume. It can be directly applied to the treatment of solid wastes such as steel slag and refining slag, achieving the "carbon fixation and alkali reduction" of solid wastes such as steel slag, and promoting the effective utilization of solid wastes such as steel slag in the cement industry.

[0038] (3) The fluidized bed reactor utilizes the fluidization process of the fluidized bed reactor to improve the reaction contact efficiency, which not only avoids the problem of insufficient gas-solid contact in traditional reactors, but also enables continuous loading and unloading of solid waste and the continuity of the reaction process. At the same time, the fluidized bed reactor provides sufficient mixing and reaction space for solid waste powder, CO2 and water mist, realizing effective fluidization of the three phases of gas, liquid and solid, and significantly improving the reaction efficiency.

[0039] (4) The auxiliary cementitious material prepared by the fluidized bed reaction device and method realizes efficient utilization of solid waste, which not only reduces the pollution of solid waste to the environment, but also saves natural resources. It can also be used as an admixture for cement or concrete, which can reduce the production cost of cement or concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of the fluidized reaction device in the present invention;

[0041] Figure 2 It is a schematic structural diagram of the fluidized bed reactor in the present invention;

[0042] Figure 3 is a flow chart of the fluidized reaction method of the present invention;

[0043] Among them, 1. fluidized bed reactor; 2. feed chamber; 3. reaction chamber; 4. air inlet chamber; 5. gas outlet; 6. solid inlet; 7. solid waste silo; 8. gas distribution plate; 9. rotary discharger; 10. solid outlet; 11. gas inlet; 12. fan; 13. atomizer; 14. solvent storage tank. DETAILED DESCRIPTION

[0044] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0045] like Figure 1 and Figure 2As shown, the fluidized reaction device for efficient mineralization of carbon dioxide from solid waste provided by the present invention comprises a fluidized bed reactor 1, in which a feed chamber 2, a reaction chamber 3 and an air inlet chamber 4 are sequentially arranged from top to bottom; a gas outlet 5 is arranged at the top of the feed chamber 2, and a solid inlet 6 is arranged at one side of the bottom end of the feed chamber 2, and the solid inlet 6 is connected to a solid waste bin 7; a gas distribution plate 8 is arranged at the connection between the reaction chamber 3 and the air inlet chamber 4, and a rotary discharger 9 is arranged at one side of the gas distribution plate 8, and the rotary discharger 9 is connected to the solid outlet 10; a gas inlet 11 is arranged at the bottom end of the air inlet chamber 4, and the gas inlet 11 is connected to a CO2 conveying device through a pipeline, and the end of the pipeline is connected to a fan 12; the middle part of the pipeline is connected to the output end of an atomizer 13, and the input end of the atomizer 13 is connected to a solvent storage tank 14.

[0046] In the fluidized reaction device, the fluidized bed reactor 1 provides a space for sufficient mixing and reaction of solid waste powder, CO2 and water mist, realizes the effective fluidization of gas, liquid and solid phases, and significantly improves the reaction efficiency; the atomizer 13 can atomize the solvent in the solvent storage tank 14 into tiny droplets, and mix them with CO2 gas and enter the reaction system together, providing sufficient moisture for the reaction, and the introduction of water mist not only promotes the mass transfer rate of CO2 to solid waste, but also enhances the mixing characteristics and reaction contact efficiency of solid waste powder; in addition, the gas inlet 11 is connected to the CO2 conveying device through a pipeline, and is conveyed by the fan 12, ensuring the stable supply of CO2 gas and the pressure stability of the reaction system, and the fan 12 can improve the mixing effect of gas and solid waste powder and promote the mineralization reaction; and the solid The waste bin 7, the solid inlet 6 and the feed chamber 2 can realize the continuous supply of solid waste powder, so that the solid waste powder can be evenly and stably added to the fluidized reaction system, avoiding the agglomeration and accumulation of the solid waste powder, and ensuring the continuity and stability of the reaction; and the gas distribution plate 8 is arranged at the connection between the reaction chamber 3 and the air inlet chamber 4, which can evenly distribute the gas and prevent the blockage and accumulation of the solid waste powder. In addition, the porous structure of the gas distribution plate 8 also increases the contact area between the gas and the solid waste powder, thereby promoting the reaction; and the rotary discharger 9 can make the reacted solid waste powder be smoothly discharged from the reaction chamber 3, and can control the discharge rate of the solid waste powder, avoiding the residue and accumulation of the solid waste powder, ensuring the completeness and efficiency of the reaction, and can realize the continuous discharge of the reaction products, providing a guarantee for the continuity of the reaction.

[0047] The fluidized bed reactor 1 utilizes the fluidization process to improve the reaction contact efficiency, which not only avoids the problem of insufficient gas-solid contact in traditional reactors, but also enables continuous loading and unloading of solid waste and continuous reaction engineering. At the same time, the fluidized bed reactor 1 provides sufficient mixing and reaction space for solid waste powder, CO2 and water mist, realizes effective fluidization of gas, liquid and solid phases, and significantly improves the reaction efficiency.

[0048] A fluidized reaction method for efficiently mineralizing carbon dioxide from solid waste produced by the above fluidized reaction device, such as Figure 3 As shown, the following steps are included:

[0049] S1: solid waste pretreatment: pretreating the solid waste particles to obtain solid waste powder with a particle size of less than 100 μm;

[0050] S2: fluidized system construction: the mixed solution containing the alkaline solvent is atomized by the atomizer 13 to obtain water mist, the mixture of CO2 gas and water mist is input into the fluidized bed reactor 1 from the gas inlet 5 by the fan 12, and the solid waste powder is added into the fluidized bed reactor 1 through the feed port 6;

[0051] S3: Solid waste mineralization reaction: water mist and solid waste powder with a mass ratio of 0.2 to 0.5 are input into the fluidized bed reactor 1, and the gas flow rate of the mixture of CO2 gas and water mist is adjusted. The mixture of CO2 gas and water mist is evenly distributed through the gas distribution plate 8 and then flows upward in the fluidized reactor 1. Driven by the gas phase of CO2 gas, the solid waste powder undergoes gas-liquid-solid three-phase fluidization in the reaction chamber 1 of the fluidized bed reactor 1. The solid waste powder in the fluidized state can fully contact with CO2 and water mist and undergo a mineralization reaction;

[0052] S4: Post-reaction treatment: After the mineralization reaction is fully completed, the solid waste powder after the reaction is discharged from the fluidized bed reactor 1 by a rotary discharger 9, and the auxiliary gelling material is obtained after being dried to a constant weight in a constant temperature drying oven.

[0053] The pretreatment operations such as crushing and ball milling in step S1 can refine the particle size of the solid waste particles, increase the specific surface area of ​​the solid waste particles, and further increase the contact efficiency between the solid waste particles and the CO2 and water mist, which is conducive to achieving a more stable gas-liquid-solid three-phase fluidization state in the fluidized bed reactor 1, thereby accelerating the mineralization reaction rate; in step S2, the water mist of the solvent is first atomized by the atomizer 13, so that the water mist solvent can be evenly dispersed in the CO2 gas to form a gas-liquid mixture, and then the CO2 gas and the water mist are atomized by the fan 12. The water mist mixture is input into the fluidized bed reactor 1 to provide a stable airflow for the fluidized bed reactor 1, which is conducive to achieving the fluidized state of the solid waste. Then, by adding solid waste powder into the fluidized bed reactor 1, the solid waste powder can be fluidized under the drive of CO2, which is conducive to the subsequent mineralization reaction. In step S3, the CO2 gas carrying water mist drives the solid waste powder to fluidize. During the fluidization process, after the solid waste powder collides with the water mist droplets, a gas-solid / gas-liquid-solid reaction interface coexists on the surface. The introduction of the liquid phase can reduce At the same time, the liquid-retaining solid waste powder undergoes non-steady-state fluidization driven by CO2 gas, which will enhance the mixing characteristics and reaction contact efficiency of the solid waste powder and promote the renewal of the mass transfer-reaction interface. Under the dual effects of the two, the absorption-mineralization efficiency of flue gas CO2 by the solid waste can be significantly improved; and the mass ratio of water mist and solid waste powder entering the fluidized bed reactor is the liquid-solid ratio. By adjusting the liquid-solid ratio, the gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1 can be controlled, which is conducive to the full contact of the solid waste powder with CO2 and water mist, thereby accelerating the reaction rate, converting cations such as alkaline earth metals in the solid waste into stable carbonates, and realizing the "carbon fixation and alkali reduction" of the solid waste; in step S4, after the mineralization reaction is fully reacted, the reacted solid waste powder is discharged from the inside of the fluidized bed reactor 1 by a rotary discharger 9, which can realize continuous production and improve production efficiency. After the discharged solid waste powder is dried to constant weight in a constant temperature drying oven, an auxiliary cementitious material can be obtained, which can replace part of the cement cementitious material and has better environmental friendliness.

[0054] This fluidized reaction method introduces water mist to form gas-liquid-solid three-phase fluidization, which effectively improves the contact efficiency between solid waste and CO2, significantly shortens the reaction time, and can achieve continuous loading and unloading of solid waste, avoiding the problem of insufficient gas-solid contact in traditional reactors.

[0055] Among them, the solid waste particles in step S1 include alkaline solid waste particles containing calcium oxide or calcium hydroxide, such as steel slag, refined slag, and waste concrete recycled micropowder; alkaline solid waste particles containing calcium oxide or calcium hydroxide are easy to undergo mineralization reaction with CO2, and then convert cations such as alkaline earth metals in the alkaline solid waste particles into stable carbonates, thereby achieving "carbon fixation and alkali reduction" of solid waste.

[0056] In step S2, the mass percentage concentration of CO2 is ≥10%, the input temperature of CO2 is 20-30°C, the gas flow rate of the mixture of CO2 gas and water mist is 0.08-0.40 m / s, and the mass fraction of the alkaline solvent in step S2 is 5%-10%, the pH of the mixed solution is 10-12, and the diameter of the water mist obtained after atomization is 200-400 μm. A higher concentration of CO2 can increase the mineralization reaction rate of solid waste powder and CO2, thereby shortening the reaction time and improving production efficiency, and the adapted temperature is conducive to maintaining the chemical stability of the solid waste powder, thereby ensuring the reaction rate; at the same time, when the gas velocity of CO2 gas is controlled between the minimum fluidization velocity and the terminal velocity of the particles, and is within the range of 0.08-0.40 m / s, it can ensure that the solid waste powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1, and at the same time, the fluidization will not be insufficient due to too low a velocity, and the solid waste powder will not be blown out of the reactor due to too high a velocity, thereby ensuring the effective conduct of the mineralization reaction. The solvent is a mixed solution containing an alkaline solvent, and its pH is 10-12, and the mass fraction of the alkaline solvent is 5%-10%, which is conducive to the mixing of CO2 in the solvent water mist, thereby increasing the mineralization reaction rate of CO2 and solid waste powder. In addition, the alkaline environment can accelerate the reaction of alkaline components in solid waste (such as calcium oxide or calcium hydroxide) with CO2 to generate more stable carbonates, and the diameter of the water mist obtained after atomization is 200-400μm, which can better mix with CO2 gas and solid waste powder, promote the formation of gas-liquid-solid three-phase fluidization, and facilitate the mineralization reaction to be more sufficient and efficient.

[0057] In step S3, the temperature of the mineralization reaction process is 20-50°C, and the time of the mineralization reaction is 5-20 minutes. The temperature during the mineralization reaction is higher than room temperature, which can improve the reaction efficiency. However, if the temperature exceeds 50°C, it is not conducive to the dissolution of CO2, resulting in a decrease in the absorption mineralization efficiency. The mineralization reaction time of 5-20 minutes can not only ensure the full progress of the reaction, but also effectively shorten the overall process time and improve production efficiency. In addition, the gas distribution plate is a hood-type gas distribution plate 8, and its setting angle is 0-20°. The gas distribution plate 8 is a porous structure with an opening rate of 2%-4%. The hood-type gas distribution plate can more effectively disperse and guide the mixture of CO2 gas and water mist into the reaction chamber of the fluidized bed reactor, thereby improving the uniformity of the mixture of CO2 gas and water mist entering the fluidized bed reactor, and facilitating the discharge of solid waste from the bottom of the fluidized bed reactor after the mineralization reaction is completed.

[0058] In step S4, the drying temperature of the constant temperature drying oven is 100-110°C, and the auxiliary cementitious material in step S4 can be used as an admixture for cement or concrete, and can replace up to 30% of cement. The auxiliary cementitious material can be used as an admixture for cement or concrete, thereby realizing efficient utilization of solid waste, which can not only reduce the pollution of solid waste to the environment, but also save natural resources and reduce the production cost of cement or concrete.

[0059] Example 1

[0060] In this embodiment, a fluidized reaction method for efficiently mineralizing carbon dioxide from solid waste is provided, wherein the solid waste particles used are recycled fine powder from waste concrete, and specifically comprises the following steps:

[0061] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0062] S2: Fluidized system construction: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0063] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.3. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0064] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0065] Example 2

[0066] This embodiment is based on the embodiment 1, and the CO2 concentration used is 99.5%, and specifically includes the following steps:

[0067] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0068] S2: Construction of fluidized system: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 99.5% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0069] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.3. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0070] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0071] Example 3

[0072] This embodiment is based on implementation 1, and the liquid-to-solid ratio is adjusted to 0.4, and specifically includes the following steps:

[0073] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0074] S2: Fluidized system construction: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0075] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.4, and drive the CO2 gas phase to produce gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro-powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0076] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0077] Example 4

[0078] Based on Example 1, this example adjusts the mineralization reaction time to 10 minutes, and specifically includes the following steps:

[0079] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0080] S2: Fluidized system construction: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0081] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.3. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0082] S4: Post-reaction treatment: After the mineralization reaction has taken place for 10 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0083] Example 5

[0084] Based on Example 1, this example adjusts the mineralization reaction time to 20 minutes, and specifically includes the following steps:

[0085] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0086] S2: Fluidized system construction: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0087] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.3, and drive the CO2 gas phase to produce gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro-powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0088] S4: Post-reaction treatment: After the mineralization reaction has taken place for 20 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0089] Comparative Example 1

[0090] This comparative example is based on Example 1, and the liquid-to-solid ratio is adjusted to 0.6, and specifically comprises the following steps:

[0091] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0092] S2: Fluidized system construction: Pure water is atomized by the atomizer 13 to obtain water mist with a diameter of 200-400 μm, CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist are mixed by the fan 12 and enter the fluidized bed reactor 1 from the gas inlet 11, and then the regenerated micro powder obtained by pretreatment is added to the fluidized bed reactor 1 from the solid inlet 6;

[0093] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.6. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-liquid-solid three-phase fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and water mist and undergo mineralization reaction;

[0094] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0095] Comparative Example 2

[0096] Compared with the embodiment, this comparative example does not have a solvent and an atomizer 13, and specifically includes the following steps:

[0097] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0098] S2: Fluidized system construction: CO2 gas with a CO2 concentration of 20% and a temperature of 25°C is introduced into the fluidized bed reactor 1 from the gas inlet 11 by using the fan 12, and then the regenerated micro powder obtained by pretreatment is added into the fluidized bed reactor 1 from the solid inlet 6;

[0099] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.3. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-solid fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and undergo a mineralization reaction;

[0100] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0101] Comparative Example 3

[0102] Based on Comparative Example 2, this comparative example adjusts the mineralization reaction time to 20 minutes, and specifically includes the following steps:

[0103] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0104] S2: Fluidized system construction: CO2 gas with a CO2 concentration of 20% and a temperature of 25°C is introduced into the fluidized bed reactor 1 from the gas inlet 11 by using the fan 12, and then the regenerated micro powder obtained by pretreatment is added into the fluidized bed reactor 1 from the solid inlet 6;

[0105] S3: Solid waste mineralization reaction: The gas flow rate of the mixture of CO2 gas and water mist is controlled to be 0.30-0.40 m / s, and the liquid-solid ratio is adjusted to 0.3. Driven by the gas phase of CO2 gas, the regenerated micro powder undergoes gas-solid fluidization in the fluidized bed reactor 1. The regenerated micro powder in the fluidized state can fully contact with CO2 and undergo a mineralization reaction;

[0106] S4: Post-reaction treatment: After the mineralization reaction has taken place for 20 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0107] Comparative Example 4

[0108] In this comparative example, based on Example 1, the fluidized bed reactor 1 is adjusted to a mineralization reactor, which specifically includes the following steps:

[0109] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0110] S2: Constructing a reaction system: atomizing pure water through an atomizer 13 to obtain water mist with a diameter of 200-400 μm, using a fan 12 to mix CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist and enter the mineralization reactor from the gas inlet 11, and then adding the regenerated micro powder obtained by pretreatment into the mineralization reactor from the solid inlet 6;

[0111] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.3, and under the drive of CO2 gas phase, the regenerated micro powder can fully contact with CO2 and water mist and undergo mineralization reaction;

[0112] S4: Post-reaction treatment: After the mineralization reaction has taken place for 5 minutes, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0113] Comparative Example 5

[0114] This comparative example is based on comparative example 4, and the mineralization reaction time is adjusted to 2 hours, and specifically comprises the following steps:

[0115] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0116] S2: Constructing a reaction system: atomizing pure water through an atomizer 13 to obtain water mist with a diameter of 200-400 μm, using a fan 12 to mix CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist and enter the mineralization reactor from the gas inlet 11, and then adding the regenerated micro powder obtained by pretreatment into the mineralization reactor from the solid inlet 6;

[0117] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.3, and under the drive of CO2 gas phase, the regenerated micro powder can fully contact with CO2 and water mist and undergo mineralization reaction;

[0118] S4: Post-reaction treatment: After the mineralization reaction has taken place for 2 hours, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0119] Comparative Example 6

[0120] This comparative example is based on comparative example 4, and the mineralization reaction time is adjusted to 4 hours, and specifically comprises the following steps:

[0121] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0122] S2: Constructing a reaction system: atomizing pure water through an atomizer 13 to obtain water mist with a diameter of 200-400 μm, using a fan 12 to mix CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist and enter the mineralization reactor from the gas inlet 11, and then adding the regenerated micro powder obtained by pretreatment into the mineralization reactor from the solid inlet 6;

[0123] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.3, and under the drive of CO2 gas phase, the regenerated micro powder can fully contact with CO2 and water mist and undergo mineralization reaction;

[0124] S4: Post-reaction treatment: After the mineralization reaction has taken place for 4 hours, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0125] Comparative Example 7

[0126] This comparative example is based on comparative example 4, and the mineralization reaction time is adjusted to 8 hours, and specifically comprises the following steps:

[0127] S1: Solid waste pretreatment: crushing and ball milling the waste concrete according to its size to obtain recycled micro powder with a particle size of less than 100 μm;

[0128] S2: Constructing a reaction system: atomizing pure water through an atomizer 13 to obtain water mist with a diameter of 200-400 μm, using a fan 12 to mix CO2 gas with a CO2 concentration of 20% and a temperature of 25°C and the atomized water mist and enter the mineralization reactor from the gas inlet 11, and then adding the regenerated micro powder obtained by pretreatment into the mineralization reactor from the solid inlet 6;

[0129] S3: Solid waste mineralization reaction: Control the gas flow rate of the mixture of CO2 gas and water mist to 0.30-0.40 m / s, adjust the liquid-solid ratio to 0.3, and under the drive of CO2 gas phase, the regenerated micro powder can fully contact with CO2 and water mist and undergo mineralization reaction;

[0130] S4: Post-reaction treatment: After the mineralization reaction has taken place for 8 hours, the regenerated micro powder after the reaction is discharged from the fluidized bed reactor 1 by means of a rotary discharger 9, and is dried in a constant temperature drying oven at a drying temperature of 100 to 110° C. to a constant weight to obtain an auxiliary gelling material.

[0131] The auxiliary cementitious materials obtained in the above-mentioned Examples 1 to 5 and Comparative Examples 1 to 7 were respectively tested for apparent carbon fixation. Since calcium carbonate decomposes at 500° C. to 850° C. and causes mass loss, the weight loss of the auxiliary cementitious material in the range of 500° C. to 850° C. was tested by pyrolysis method as the CO2 fixation amount. The mass loss of carbonate decomposition was normalized according to the initial powder mass, and the apparent carbon fixation amount of the auxiliary cementitious material was calculated. The results of the carbon fixation amount of the auxiliary cementitious material under different reaction methods are shown in Table 1:

[0132] Table 1

[0133]

[0134]

[0135] As shown in Table 1, it can be seen from Example 1 and Example 2 that when other conditions are the same, the CO2 concentration in Example 1 is 20%, and the carbon fixation amount of the obtained auxiliary cementitious material is 13.37%. The CO2 concentration in Example 2 is 99.5%, and the carbon fixation amount of the obtained auxiliary cementitious material is 14.15%. Under the three-phase fluidized state, the regenerated micropowder powder and the CO2 gas can be fully in contact. When the concentration of CO2 gas is high, the mass transfer driving force from the gas phase to the liquid phase or the solid phase is greater, the reaction efficiency and the carbon fixation rate of the material are higher, and the solid waste particles can achieve a higher carbon fixation amount at a higher CO2 concentration. It can be seen from Example 1 and Example 3 that when other conditions are the same, the liquid-solid ratio in Example 1 is 0.3, and the liquid-solid ratio in Example 3 is 0.4, and the carbon fixation amount of the auxiliary cementitious material is 15.30%. Under the three-phase fluidized state, when the liquid-solid ratio is larger, the water mist in the gas phase can be evenly dispersed on the surface of the regenerated micro-powder particles to form a gas-liquid-solid three-phase mass transfer reaction interface, which will accelerate the mineralization reaction efficiency of the solid waste, that is, the solid waste particles can achieve a higher carbon fixation amount at a higher liquid-solid ratio. It can be seen from Example 1, Example 4 and Example 4 that when other conditions are the same, the carbon fixation rate can be increased by adjusting the mineralization reaction time, that is, the solid waste particles can achieve a higher carbon fixation amount at a longer mineralization reaction time.

[0136] It can be seen from Example 1 and Comparative Example 1 that when the fluidized bed reactor 1 is used as a mineralization reaction vessel for regenerated micropowder powder, a higher liquid-solid ratio will lead to the production of excessive water mist droplets, which will in turn cause the regenerated micropowder powder particles to agglomerate, and part of the regenerated micropowder powder will be wrapped, reducing the contact efficiency between the regenerated micropowder powder and the CO2 gas in the gas phase, and causing the carbon fixation rate of the auxiliary cementitious material to drop from 13.37% in Example 1 to 10.74% in Comparative Example 1, that is, a higher liquid-solid ratio will affect the mineralization efficiency.

[0137] It can be seen from Example 1, Example 5, Comparative Example 2 and Comparative Example 3 that when other conditions are the same, the atomizer 13 is not provided, that is, water mist is not introduced into the fluidized bed reactor 1, and a gas-solid two-phase fluidized reaction system exists in the fluidized bed reactor 1. At this time, the regenerated micropowder can fully contact with the CO2 gas in the gas phase, but only gas-solid mass transfer reaction occurs in the fluidized bed reactor 1, and the mass transfer rate is slow, which leads to a low carbon fixation rate of the auxiliary cementitious material.

[0138] It can be seen from Example 1, Example 4, Example 5 and Comparative Examples 5 to 7 that when other conditions are the same, Example 1, Example 4 and Example 5 all use fluidized bed reactor 1 as the reaction device, and Comparative Examples 5 to 7 use a mineralization reactor as the reaction device. The solid waste mineralization reaction efficiency in the fluidized bed reactor 1 is significantly enhanced, and the carbon fixation rate of the reaction in the mineralization reactor for 2 hours is only 11.39%, which is lower than the carbon fixation rate of 13.37% in the fluidized bed reactor 1 for 5 minutes; the carbon fixation rate of the reaction in the reactor for 4 hours is only 17.24%, which is less than the carbon fixation rate of 18.82% in the fluidized bed reactor 1 for 20 minutes. Therefore, the gas-liquid-solid three-phase fluidization system can significantly improve the efficiency of the solid waste mineralization reaction.

[0139] In order to verify the performance of the auxiliary cementitious material, the auxiliary cementitious material obtained in Example 1, Comparative Example 2 and Comparative Example 4 was used to prepare concrete, and the compressive strength of the concrete was tested. The auxiliary cementitious material was mixed as an admixture of cement or concrete as follows: by adding 30% of the auxiliary cementitious material to cement to prepare a composite cement, adding water according to a water-cement ratio of 0.3-0.4:1.0, stirring for 110-130 seconds, pausing for 10-20 seconds and then stirring for 110-130 seconds to obtain a composite cement slurry; pouring the composite cement slurry into a mold coated with a lubricant, vibrating and scraping off the excess slurry on the surface, placing it in an environment of 18-22°C and 90%-95%RH for curing for 24 hours, demolding, and curing for 28 days to obtain a concrete block. The measured compressive strength results are shown in Table 2:

[0140] Table 2

[0141] Test No. Compressive strength(MPa) Example 1 40.08 Comparative Example 2 27.33 Comparative Example 4 32.56

[0142] It can be seen from Table 2 that due to the low efficiency of the solid waste mineralization reaction in Comparative Examples 2 and 4, components such as calcium oxide or calcium hydroxide in the regenerated micropowder failed to effectively react with the CO2 gas in the gas phase for mineralization, resulting in a low content of calcium carbonate generated. Compared with Example 1, even if the same amount of auxiliary cementitious material is added, the auxiliary cementitious material in Example 1 can effectively fill the pores in the mixed cement, promote the nucleation and growth of calcium silicate hydrate, and thus improve the strength performance of the mixed cement. That is, the fluidized reaction method in Example 1 can significantly reduce the alkalinity of the regenerated micropowder in the same or shorter time, so that it can generate more calcium carbonate, thereby making up for the defects after the cement is replaced.

[0143] In summary, the fluidized reaction device and method for efficient mineralization of carbon dioxide from solid waste provided by the present invention adopt a gas-liquid-solid three-phase fluidized reaction to improve the contact efficiency between solid waste and CO2, and adopt a water mist medium to promote the mass transfer rate of CO2 to solid waste, so that the solid waste can react quickly with CO2 gas in the fluidized bed reactor 1, significantly shortening the reaction time, thereby achieving low cost and high efficiency of the CO2 reaction for the mineralization of solid waste powder.

Claims

1. A fluidized reaction method for efficient mineralization of carbon dioxide from solid waste, characterized in that: The following steps are involved: S1: solid waste pretreatment: pretreating the solid waste particles to obtain solid waste powder with a particle size of less than 100 μm; S2: fluidized system construction: a mixed solution containing an alkaline solvent is atomized by an atomizer (13) to obtain water mist, a mixture of CO2 gas and water mist is fed into a fluidized bed reactor (1) from a gas inlet (5) by a blower (12), and solid waste powder is added into the fluidized bed reactor (1) through a feed port (6); S3: Solid waste mineralization reaction: water mist and solid waste powder with a mass ratio of 0.2 to 0.5 are input into the fluidized bed reactor (1), and the gas flow rate of the mixture of CO2 gas and water mist is adjusted. The mixture of CO2 gas and water mist is evenly distributed through the gas distribution plate (8) and then flows upward in the fluidized reactor (1). Driven by the gas phase of CO2 gas, the solid waste powder undergoes gas-liquid-solid three-phase fluidization in the reaction chamber (1) of the fluidized bed reactor (1). The solid waste powder in the fluidized state can fully contact with CO2 and water mist and undergo a mineralization reaction; S4: Post-reaction treatment: After the mineralization reaction is fully completed, the solid waste powder after the reaction is discharged from the fluidized bed reactor (1) by a rotary discharger (9), and dried in a constant temperature drying oven to a constant weight to obtain an auxiliary gelling material.

2. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The solid waste particles in S1 are alkaline solid waste particles containing calcium oxide or calcium hydroxide.

3. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The mass percentage concentration of CO2 in the S2 is ≥10%, and the input temperature of CO2 is 20-30°C.

4. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The diameter of the water mist obtained after atomization in S2 is 200-400 μm.

5. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The mass fraction of the alkaline solvent in S2 is 5% to 10%, and the pH of the mixed solution is 10 to 12.

6. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The gas flow rate of the mixture of CO2 gas and water mist in the S3 is 0.08-0.40 m / s, and the mineralization reaction time is 5-20 min.

7. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The gas distribution plate in S3 is a hood-type gas distribution plate (8), the opening rate of which is set to 2% to 4%, and the inclination angle is 0 to 20°.

8. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, characterized in that: The drying temperature in S4 is 100-110°C.

9. The fluidized reaction method for efficient mineralization of carbon dioxide from solid waste according to claim 1, further comprising: the auxiliary cementitious material in S4 can be used as an admixture for cement or concrete.

10. A fluidized reaction device for efficient mineralization of carbon dioxide from solid waste, characterized in that: It comprises a fluidized bed reactor (1), wherein the fluidized bed reactor (1) is provided with a feed chamber (2), a reaction chamber (3) and an air intake chamber (4) in sequence from top to bottom; The top of the feed chamber (2) is provided with a gas outlet (5), and the bottom of the feed chamber (2) is provided with a solid inlet (6), and the solid inlet (6) is connected to a solid waste bin (7); A gas distribution plate (8) is provided at the connection between the reaction chamber (3) and the gas inlet chamber (4), a rotary discharger (9) is provided on one side of the gas distribution plate (8), and the rotary discharger (9) is connected to a solid outlet (10); A gas inlet (11) is provided at the bottom end of the air inlet chamber (4), and the gas inlet (11) is connected to a CO2 delivery device via a pipeline, and the end of the pipeline is connected to a fan (12) for delivering CO2 gas; the middle of the pipeline is connected to the output end of an atomizer (13), and the input end of the atomizer (13) is connected to a solvent storage tank (14) for delivering water mist.

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