Method and system for multi-solid waste synergistic coupling enhanced carbonation

Abstract

The application relates to a method and system for multi-solid waste synergistic coupling and enhanced carbonation, which comprises the following steps: mixing steel slag and desulfurization ash once to obtain a steel slag-desulfurization ash mixture; mixing the steel slag-desulfurization ash mixture with water twice to obtain a solid waste mixed slurry; introducing CO2 into the solid waste mixed slurry to perform a carbonation reaction, and then filtering the solid waste mixed slurry after the carbonation reaction to obtain carbonated solid waste and filtrate. The synergistic effect of steel slag and desulfurization ash can significantly improve the carbon sequestration efficiency. The desulfurization ash can not only inhibit the formation of a carbonate passivation layer on the surface of the solid waste to expand the reaction interface, but also promote the dissolution and release of active calcium components in the steel slag through ion replacement, thereby synergistically accelerating the carbonation reaction process. The method introduces CO2 into the solid waste mixed slurry to perform a carbonation reaction, and finally realizes efficient synergy of solid waste resource utilization and CO2 emission reduction, thereby providing key technical support for low-carbon transformation of the steel industry.

Description

Technical Field

[0001] This application relates to the field of solid waste treatment technology, and in particular to a method and system for enhanced carbonation through synergistic coupling of multiple solid wastes. Background Technology

[0002] Mineral carbonation technology is a key pathway for achieving long-term carbon dioxide sequestration. This technology simulates the natural weathering process, utilizing the reaction between alkaline earth metal oxides (such as calcium and magnesium) and CO2 to generate thermodynamically stable carbonate minerals, thereby permanently solidifying the carbon. Solid waste generated during the steel industry (such as steel slag and desulfurization ash) is rich in highly reactive calcium and magnesium components, providing an ideal source of raw materials for mineralization reactions. Using such solid waste as mineralization raw materials to sequester CO2 generated during steel production can construct a synergistic "waste-to-waste" technology system. This system has the dual benefits of reducing carbon emissions and disposing of solid waste, and is one of the core means to promote the green and low-carbon transformation of the steel industry.

[0003] Currently, the development of direct carbonation technology for solid waste is generally limited by its reliance on a single solid waste system. A core bottleneck lies in the rapid formation of a dense carbonate product layer on the surface of solid waste particles during the reaction. This covering layer severely hinders the diffusion of active ions such as calcium and magnesium from the interior to the reaction interface, leading to rapid interface passivation. As the carbonate layer thickens, the carbonation reaction rate declines exponentially and eventually stagnates, severely limiting the carbon sequestration potential of the solid waste itself. This results in a dilemma of low carbon sequestration efficiency and low resource utilization, becoming a key obstacle to the large-scale application of the technology.

[0004] To overcome these limitations, existing research mainly follows two paths: one is to directly conduct a liquid-phase reaction between solid waste slurry and CO2, but this fails to fundamentally solve the problem of reaction termination caused by surface passivation; the other is to introduce porous carriers (such as biochar) as additional carbonate deposition sites, which alleviates the covering effect to some extent, but still cannot completely prevent the formation of a passivation layer on the surface of the solid waste particles themselves. Overall, existing technologies have failed to fundamentally solve the core problem of reaction interface deactivation, resulting in limited room for improvement in carbon sequestration capacity. Summary of the Invention

[0005] This application provides a method and system for enhanced carbonation through synergistic coupling of multiple solid wastes, in order to solve the following technical problem: how to improve the carbon sequestration efficiency of solid wastes.

[0006] In a first aspect, embodiments of this application provide a method for enhanced carbonation through synergistic coupling of multiple solid wastes, the method comprising: Steel slag and desulfurization ash are mixed once to obtain a steel slag-desulfurization ash mixture; the mass ratio of steel slag to desulfurization ash is 10:1 to 1:2. The steel slag-desulfurization ash mixture is mixed with water a second time to obtain a solid waste slurry; wherein the liquid-solid ratio of the steel slag-desulfurization ash mixture to the water is 2:1 to 50:1. CO2 is introduced into the solid waste mixture to carry out a carbonation reaction, and then the carbonation reaction solid waste mixture is filtered to obtain carbonated solid waste and filtrate. In this process, sulfite ions in the desulfurization ash hydrolyze to generate bisulfite ions, which then dissociate to produce hydrogen ions, creating a localized acidic microenvironment on the surface of the steel slag particles to dissolve the calcium carbonate passivation layer. Sulfate ions in the desulfurization ash undergo a displacement reaction with silicate minerals in the steel slag, converting calcium silicate into calcium hydroxide.

[0007] Optionally, the primary mixing is carried out in a grinder with a rotation speed ≤1000 rpm and a primary mixing time ≤60 min.

[0008] Optionally, the secondary mixing is carried out in a reaction vessel, and the rotation speed of the reaction vessel is 50 rpm to 500 rpm.

[0009] Optionally, the CO2 is introduced from the bottom of the reactor through an aeration disc, and the CO2 gas flow rate is 1L / min to 20L / min.

[0010] Optionally, the carbonation reaction time is 5 min to 120 min.

[0011] Optionally, the steel slag is a solid waste generated during the converter steelmaking process, and the desulfurization ash is a solid waste generated during the semi-dry desulfurization process.

[0012] Optionally, the carbonated solid waste is used for the preparation of building materials, and the filtrate is treated to meet discharge standards.

[0013] Secondly, embodiments of this application provide a system for synergistic coupling and enhanced carbonation of multiple solid wastes, the system being adapted to the method described in the first aspect, the system comprising: Carbon fixation device 1 is used to contain the steel slag-desulfurization ash mixture slurry and provide space for carbonation reaction; CO2 cylinder 2 is connected to the carbon fixation device 1 and is used to introduce CO2 gas into the carbon fixation device 1. The filtration device 3 is connected to the carbon fixation device 1 and is used to filter and separate the slurry after the carbonation reaction to obtain carbonated solid waste 9 and carbonated filtrate 8. Planetary ball mill 7 is located upstream of the carbon fixation device 1 and is used to grind and mix steel slag 4 and desulfurization ash 5 to obtain steel slag-desulfurization ash mixture. An electronic balance 6 is installed upstream of the planetary ball mill 7 and is used to weigh and proportion the steel slag 4 and desulfurization ash 5. Thermogravimetric analyzer 10 is located downstream of the filter device 3 and is used to perform thermogravimetric analysis on the carbonated solid waste 9 to calculate the degree of carbonation.

[0014] Optionally, the carbon fixation device 1 is provided with an aeration disc at the bottom, and the CO2 gas cylinder 2 introduces CO2 gas into the solid waste mixture slurry in the carbon fixation device 1 through the aeration disc.

[0015] Optionally, the carbon fixation device 1 is equipped with a stirring device to ensure that the steel slag-desulfurization ash mixture slurry is fully contacted and reacted with CO2 gas.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method and system for synergistically enhanced carbonation of multiple solid wastes. The method includes: mixing steel slag and desulfurization ash once to obtain a steel slag-desulfurization ash mixture; mixing the steel slag-desulfurization ash mixture with water a second time to obtain a solid waste slurry; introducing CO2 into the solid waste slurry to carry out a carbonation reaction; and then filtering the carbonation-reacted solid waste slurry to obtain carbonated solid waste and filtrate. The introduction of desulfurization ash provides a key synergistic enhancement mechanism for the carbonation process of steel slag. Specifically, bisulfite ions in the desulfurization ash dissociate to generate hydrogen ions during the reaction, thereby constructing a locally acidic microenvironment on the surface of steel slag particles. This slightly acidic condition can selectively dissolve the formed calcium carbonate passivation layer, continuously exposing fresh reaction interfaces inside, effectively overcoming the kinetic limitation of calcium ion diffusion by the product coating layer, and driving the carbonation reaction to continue deep into the particles. At the same time, sulfate ions contained in the desulfurization ash can convert calcium elements in the silicate minerals of steel slag into highly active calcium hydroxide through a displacement reaction. This process achieves a fundamental shift from physical dissolution to chemical activation of calcium components, significantly increasing the release rate and concentration of calcium ions, thereby providing a sufficient and efficient calcium source for continuous carbonation reactions.

[0017] In summary, the synergistic effect of steel slag and desulfurization ash, through a dual pathway of dynamic deactivation of the passivation layer and enhanced activity of calcium components, simultaneously overcomes two core bottlenecks in the carbonation process of solid waste: deactivation of the reaction interface and insufficient calcium ion supply. In this system, desulfurization ash plays two key roles: first, as a passivation layer remover, it continuously exposes fresh reaction interfaces to maintain their activity by constructing an acidic microenvironment dissolution product coating layer; second, as a chemical activator, it transforms the inert calcium components in the steel slag into highly active forms through ion exchange, significantly increasing the calcium ion release rate and concentration. Meanwhile, the steel slag provides an abundant calcium matrix, serving as the basic raw material for the reaction. The two are coupled together, forming a strengthened cycle that continuously breaks down interfacial barriers and simultaneously supplies an active calcium source. This fundamentally optimizes the reaction kinetics, ultimately achieving a breakthrough improvement in carbon fixation efficiency. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] Figure 1 A flowchart of a method for enhanced carbonation through synergistic coupling of multiple solid wastes provided in this application embodiment; Figure 2 A schematic diagram of the system logic structure for enhanced carbonation through synergistic coupling of multiple solid wastes provided in this application embodiment; wherein, 1, carbon fixation device; 2, CO2 cylinder; 3, filtration device; 4, steel slag; 5, desulfurization ash; 6, electronic balance; 7, planetary ball mill; 8, carbonation filtrate; 9, carbonation solid waste; 10, thermogravimetric analyzer; Figure 3 This is a mechanism diagram of a method for enhanced carbonation through synergistic coupling of multiple solid wastes, provided in an embodiment of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0022] The range descriptions used herein, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges between 1 and 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "contains" used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship. "And / or" indicates that multiple situations can exist individually or simultaneously. Expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships mentioned herein, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained through commercial purchase or prepared using existing methods.

[0023] Figure 1 This is a flowchart of a method for enhanced carbonation through synergistic coupling of multiple solid wastes, provided as an embodiment of this application.

[0024] Please see Figure 1 This application provides a method for enhanced carbonation through synergistic coupling of multiple solid wastes, the method comprising: S1. Steel slag and desulfurization ash are mixed once to obtain steel slag-desulfurization ash mixture; the mass ratio of steel slag to desulfurization ash is 10:1~1:2; S2. The steel slag-desulfurization ash mixture is mixed with water for a second time to obtain a solid waste slurry; wherein the liquid-solid ratio of the steel slag-desulfurization ash mixture to the water is 2:1 to 50:1. S3. CO2 is introduced into the solid waste mixture to carry out a carbonation reaction, and then the solid waste mixture after the carbonation reaction is filtered to obtain carbonated solid waste and filtrate. In this process, sulfite ions in the desulfurization ash hydrolyze to generate bisulfite ions, which then dissociate to produce hydrogen ions, creating a localized acidic microenvironment on the surface of the steel slag particles to dissolve the calcium carbonate passivation layer. Sulfate ions in the desulfurization ash undergo a displacement reaction with silicate minerals in the steel slag, converting calcium silicate into calcium hydroxide.

[0025] The main components of desulfurization ash are calcium sulfite hemihydrate, calcium sulfate hemihydrate, and calcium sulfate dihydrate.

[0026] In the above technical solution, carbonation enhancement is achieved through the synergistic effect of steel slag and desulfurization ash. During the carbonation reaction stage, sulfite ions (SO32-) in the desulfurization ash... 2- Hydrolysis produces bisulfite (HSO3)- The latter dissociates and releases H + A localized acidic microenvironment is formed (1). This acidic condition continuously dissolves the dense calcium carbonate passivation layer on the surface of the steel slag, exposing a fresh reaction interface and breaking the kinetic limitation of the product layer on the in-depth reaction; at the same time, sulfate ions (SO4) in the desulfurization ash... 2- The inert calcium silicate undergoes a displacement reaction (3) with the silicate minerals in the steel slag, converting it into highly active calcium hydroxide (Ca(OH)2), which significantly enhances the chemical release activity of calcium ions.

[0027] (1) (2) (3) In some embodiments, the mass ratio of the steel slag to the desulfurization ash is 10:1 to 1:2.

[0028] By precisely controlling the mass ratio of steel slag to desulfurization ash between 10:1 and 1:2, the desulfurization ash can fully activate the calcium components in the steel slag while avoiding interference from impurity ions due to excessive introduction of desulfurization ash, thereby maximizing the synergistic carbon fixation efficiency. For example, the mass ratio of steel slag to desulfurization ash can be 10:1, 4:1, 2:1, 1:1, 1:1.5, 1:2, etc.

[0029] In some embodiments, the primary mixing is carried out in a grinder with a rotation speed ≤1000 rpm and a primary mixing time ≤60 min.

[0030] The initial mixing is carried out in a grinding mill at a speed ≤1000 rpm. This prevents the desulfurization ash from decomposing and deactivating due to overheating by suppressing the temperature rise caused by excessive mechanical energy input. Ultimately, this ensures the integrity of the interface passivation inhibition and calcium component activation functions of the desulfurization ash during the subsequent carbonation reaction. For example, the grinding mill speed can be 200 rpm, 400 rpm, 600 rpm, 800 rpm, or 1000 rpm. The initial mixing time is ≤60 min to avoid oxidation failure of the desulfurization ash caused by over-grinding, thereby maintaining the reducing activity of the sulfite component and ultimately ensuring the stability of the passivation layer dissolution and calcium activation functions of the desulfurization ash during the subsequent carbonation reaction. For example, the initial mixing time can be 20 min, 30 min, 40 min, 50 min, or 60 min.

[0031] In some embodiments, the liquid-solid ratio of the steel slag-desulfurization ash mixture to the water is 2:1 to 50:1.

[0032] The liquid-to-solid ratio of the steel slag-desulfurization ash mixture to water is between 2:1 and 50:1. This aims to optimize the balance between mass transfer conditions and reaction interface exposure in the slurry: a lower liquid-to-solid ratio (2:1) ensures sufficient dispersion of solid waste particles and the formation of a adequate effective reaction interface; a higher liquid-to-solid ratio (50:1) avoids excessive water dilution of calcium ion concentration, thus preventing inhibition of carbonation reaction kinetics. Precise control of the liquid-to-solid ratio achieves an optimal balance between the reaction interface and mass transfer conditions, thereby synergistically improving carbon fixation efficiency. For example, the liquid-to-solid ratio of the steel slag-desulfurization ash mixture to water can be 2:1, 10:1, 20:1, 30:1, 40:1, 50:1, etc.

[0033] In some embodiments, the secondary mixing is carried out in a reaction vessel at a rotation speed of 50 rpm to 500 rpm.

[0034] Secondary mixing takes place in a reactor at a rotation speed between 50 rpm and 500 rpm. This aims to maintain the slurry in an optimal balance between fluidization and particle suspension: ensuring sufficient dispersion of solid waste particles to expose the maximum reaction interface while avoiding damage to the synergistic microstructure formed between desulfurization ash and steel slag due to high-speed shearing, thereby optimizing the overall kinetics of the carbonation reaction. For example, the reactor rotation speed can be 50 rpm, 200 rpm, 350 rpm, or 500 rpm.

[0035] In some embodiments, the CO2 is introduced from the bottom of the reactor through an aeration disc, and the CO2 gas flow rate is 1L / min to 20L / min.

[0036] CO2 is introduced from the bottom of the reactor through an aeration disc to enhance gas dispersion and effectively extend the gas-liquid contact path, thereby significantly increasing the specific surface area for CO2 mass transfer. Simultaneously, the rising gas drives convective mixing of the slurry, promoting the uniform distribution of the locally acidic microenvironment constructed by desulfurization ash, ultimately achieving efficient carbonation and fixation of calcium ions. The CO2 gas flow rate is between 1 L / min and 20 L / min to balance the mass transfer efficiency of CO2 in the solid waste mixture slurry with the concentration stability within the system, thus optimizing the overall carbonation reaction rate: too low a CO2 gas flow rate will lead to insufficient CO2 supply, limiting the reaction process; too high a CO2 gas flow rate may cause CO2 to escape before fully dissolving and reacting, resulting in resource waste. This optimized range ensures that CO2 can continuously and efficiently participate in and drive the carbonation reaction. For example, the CO2 gas flow rate can be 5 L / min, 10 L / min, 15 L / min, 20 L / min, etc.

[0037] In some embodiments, the carbonation reaction takes 5 to 120 minutes.

[0038] The carbonation reaction time is between 5 and 120 minutes to achieve an optimal balance between the degree of reaction and the process energy cost: too short a carbonation reaction time will result in incomplete carbonation and a low carbon fixation rate; while too long a carbonation reaction time will lead to unnecessary energy consumption due to the extremely low subsequent reaction rate. By conducting the reaction within a specified time, ineffective energy consumption can be effectively avoided while ensuring carbon fixation efficiency, thus achieving an optimal balance between reaction efficiency and operating cost. For example, the carbonation reaction time can be 20 minutes, 40 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, etc.

[0039] In some embodiments, the steel slag is a solid waste generated during the converter steelmaking process, and the desulfurization ash is a solid waste generated by the semi-dry desulfurization process.

[0040] In some embodiments, the carbonated solid waste is used in the preparation of building materials, and the filtrate is treated to meet discharge standards.

[0041] Figure 2 This is a schematic diagram of the system logic structure for enhanced carbonation through synergistic coupling of multiple solid wastes, provided in an embodiment of this application.

[0042] Based on a general inventive concept, such as Figure 2 As shown, this application provides a system for enhanced carbonation through synergistic coupling of multiple solid wastes, the system being adapted to the method described in the first aspect, the system comprising: Carbon fixation device 1 is used to contain the steel slag-desulfurization ash mixture slurry and provide space for carbonation reaction; CO2 cylinder 2 is connected to the carbon fixation device 1 and is used to introduce CO2 gas into the carbon fixation device 1. The filtration device 3 is connected to the carbon fixation device 1 and is used to filter and separate the slurry after the carbonation reaction to obtain carbonated solid waste 9 and carbonated filtrate 8. Planetary ball mill 7 is located upstream of the carbon fixation device 1 and is used to grind and mix steel slag 4 and desulfurization ash 5 to obtain steel slag-desulfurization ash mixture. An electronic balance 6 is installed upstream of the planetary ball mill 7 and is used to weigh and proportion the steel slag 4 and desulfurization ash 5. Thermogravimetric analyzer 10 is located downstream of the filter device 3 and is used to perform thermogravimetric analysis on the carbonated solid waste 9 to calculate the degree of carbonation.

[0043] The system is implemented based on the above method. The specific steps of the method can be referred to the above embodiments. Since the system adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0044] In some embodiments, the carbon fixation device 1 is provided with an aeration disc at the bottom, and the CO2 gas cylinder 2 introduces CO2 gas into the solid waste mixture slurry in the carbon fixation device 1 through the aeration disc.

[0045] In some embodiments, the carbon fixation device 1 is equipped with a stirring device to ensure that the steel slag-desulfurization ash mixture slurry is fully contacted and reacted with CO2 gas.

[0046] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards / industry standards / the disclosure herein; if there are no corresponding national standards / industry standards / the disclosure herein, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0047] The chemical composition (mass percentage / %) of steel slag, steel slag tailings and desulfurization ash in the examples and comparative examples is shown in Table 1.

[0048] Table 1

[0049] Example 1 Steel slag and desulfurization ash were weighed at a mass ratio of 2:1. The weighed steel slag and desulfurization ash were then ground in a ball mill at a speed of 500 rpm for 30 minutes to obtain a steel slag-desulfurization ash mixture. The steel slag-desulfurization ash mixture and water were added to the reactor at a liquid-solid ratio of 3:1 for secondary mixing. The reactor was rotated at 500 rpm to obtain a solid waste mixture slurry. CO2 is introduced into the solid waste mixture to carry out a carbonation reaction. The CO2 is introduced from the bottom of the reactor through an aeration plate at a flow rate of 10 L / min, and the carbonation reaction time is 30 min. The carbonation reaction mixture is then filtered to obtain carbonated solid waste and filtrate.

[0050] Example 2 Steel slag and desulfurization ash were weighed at a mass ratio of 1:1. The weighed steel slag and desulfurization ash were then ground in a ball mill at a speed of 650 rpm for 30 minutes to obtain a steel slag-desulfurization ash mixture. The steel slag-desulfurization ash mixture and water were added to the reactor at a liquid-solid ratio of 5:1 for secondary mixing. The reactor was rotated at 500 rpm to obtain a solid waste mixture slurry. CO2 is introduced into the solid waste mixture to carry out a carbonation reaction. The CO2 is introduced from the bottom of the reactor through an aeration plate at a flow rate of 15 L / min, and the carbonation reaction takes 30 min. The carbonation reaction is then carried out by filtering the solid waste mixture after carbonation to obtain carbonated solid waste and filtrate.

[0051] Comparative Example 1 The steel slag was ground in a ball mill at 500 rpm for 30 minutes for a first mixing. The steel slag and water were then added to a reactor at a liquid-solid ratio of 3:1 for a second mixing to obtain a steel slag slurry. CO2 was introduced into the steel slag slurry to carry out a carbonation reaction. The CO2 was introduced from the bottom of the reactor through an aeration disc at a flow rate of 10 L / min, and the carbonation reaction time was 30 minutes. The carbonation reaction slurry was then filtered to obtain carbonated steel slag and filtrate.

[0052] Comparative Example 2 The desulfurization ash was ground in a ball mill at 500 rpm for 30 minutes for a first mixing. The first mixing of the desulfurization ash and water was then added to a reactor at a liquid-solid ratio of 3:1 for a second mixing to obtain a desulfurization ash slurry. CO2 was introduced into the desulfurization ash slurry for a carbonation reaction. The CO2 was introduced from the bottom of the reactor through an aeration disc at a flow rate of 10 L / min, and the carbonation reaction time was 30 minutes. The desulfurization ash slurry after the carbonation reaction was then filtered to obtain carbonated desulfurization ash and filtrate.

[0053] Comparative Example 3 The steel slag was first mixed by grinding it in a ball mill at 650 rpm for 30 minutes. Then, the steel slag and water were added to a reactor at a liquid-solid ratio of 5:1 for a second mixing to obtain a steel slag slurry. CO2 was then introduced into the steel slag slurry to carry out a carbonation reaction. The CO2 was introduced from the bottom of the reactor through an aeration plate at a flow rate of 15 L / min, and the carbonation reaction time was 30 minutes. The carbonation reaction slurry was then filtered to obtain carbonated steel slag and filtrate.

[0054] Comparative Example 4 The desulfurization ash was ground in a ball mill at 650 rpm for 30 minutes for a first mixing. The first mixing of the desulfurization ash and water was then added to a reactor at a liquid-solid ratio of 5:1 for a second mixing to obtain a desulfurization ash slurry. CO2 was introduced into the desulfurization ash slurry for a carbonation reaction. The CO2 was introduced from the bottom of the reactor through an aeration plate at a flow rate of 15 L / min, and the carbonation reaction time was 30 minutes. The desulfurization ash slurry after the carbonation reaction was then filtered to obtain carbonated desulfurization ash and filtrate.

[0055] Results data: The degree of carbonation of the examples and comparative examples is shown in Table 2.

[0056] Experimental methods for obtaining effect data: 1. Degree of carbonation: Degree of carbonation ζ Ca It is calculated from equation (1), where MW Ca and MW CO2 These represent the molar masses of calcium and carbon dioxide, respectively; Ca total Δm represents the mass fraction of calcium in the steel slag; CO2 (wt%) represents the mass fraction of CO2 in the carbonized steel slag, calculated by equation (2). 500 1000℃ This represents the mass loss caused by the decomposition of calcium carbonate in steel slag after carbonation within a temperature range of 500℃ to 1000℃, determined by a thermogravimetric analyzer; m 105℃ This indicates the mass of the carbonized steel slag after drying at 105℃.

[0057] (1) (2) Table 2

[0058] The above effect data table provides a clear comparison of the differences between various embodiments and comparative examples. The following conclusions can be drawn: As shown in Examples 1-2 and Comparative Examples 1-4, the synergistic effect of steel slag and desulfurization ash in Examples 1-2 produced a significant strengthening effect. The degree of carbonation in Example 1 reached 52.61%, far exceeding the simple sum of 37.44% for the single steel slag system (Comparative Example 1, carbonation 10.29%) and the single desulfurization ash system (Comparative Example 2, carbonation 27.15%) corresponding to Example 1. The degree of carbonation in Example 2 was even higher at 65.35%, also far exceeding the performance of the single steel slag system (Comparative Example 3, 17.92%) and the single desulfurization ash system (Comparative Example 4, 36.43%) corresponding to Example 2. This directly proves that the dual synergistic mechanism of passivation layer dissolution and calcium component activation played a key role between the two solid wastes. Conversely, the degree of carbonation in all single solid waste systems (Comparative Examples 1-4) was at a low level, with a maximum of only 36.43%, clearly limited by the inherent bottleneck of surface passivation of steel slag or insufficient calcium source of desulfurization ash itself. Therefore, Examples 1 and 2 strongly demonstrate the core advantages of the proposed multi-solid waste synergistic coupling technology in overcoming reaction kinetic limitations and improving carbon sequestration efficiency.

[0059] Appendix Figure 3 Detailed explanation: Figure 3 This is a mechanism diagram of a method for enhanced carbonation through synergistic coupling of multiple solid wastes, provided in an embodiment of this application. According to... Figure 2 It is known that the carbonate product layer (calcium carbonate) covering the surface of solid waste particles (such as steel slag) is an obstacle to the in-depth reaction. Sulfite (SO32-) in desulfurization ash... 2- First, it hydrolyzes to generate bisulfite (HSO3). - ), and then dissociate H + In the liquid boundary layer, the calcium carbonate passivation layer on the surface continues to dissolve, exposing the unreacted nuclei inside and maintaining the activity of the reaction interface; at the same time, sulfate ions (SO4) in the desulfurization ash... 2- The calcium silicate reacts with silicate minerals (such as Ca2SiO4) in the steel slag, converting inert calcium silicate into highly reactive Ca(OH)2, releasing Ca2+. 2+ CO3 is generated by dissolving CO2. 2- The two components combine to form new CaCO3, achieving efficient mineralization of calcium components. Their synergistic effect drives the carbonation reaction from the surface of solid waste particles deeper, ultimately improving carbon sequestration efficiency.

[0060] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A method for enhanced carbonation through synergistic coupling of multiple solid wastes, characterized in that, The method includes: Steel slag and desulfurization ash are mixed once to obtain a steel slag-desulfurization ash mixture; the mass ratio of steel slag to desulfurization ash is 10:1 to 1:

2. The steel slag-desulfurization ash mixture is mixed with water a second time to obtain a solid waste slurry; wherein the liquid-solid ratio of the steel slag-desulfurization ash mixture to the water is 2:1 to 50:

1. CO2 is introduced into the solid waste mixture to carry out a carbonation reaction, and then the carbonation reaction solid waste mixture is filtered to obtain carbonated solid waste and filtrate. In this process, sulfite ions in the desulfurization ash hydrolyze to generate bisulfite ions, which then dissociate to produce hydrogen ions, creating a localized acidic microenvironment on the surface of the steel slag particles to dissolve the calcium carbonate passivation layer. Sulfate ions in the desulfurization ash undergo a displacement reaction with silicate minerals in the steel slag, converting calcium silicate into calcium hydroxide.

2. The method according to claim 1, characterized in that, The primary mixing is carried out in a grinder with a rotation speed ≤1000 rpm and a primary mixing time ≤60 min.

3. The method according to claim 1, characterized in that, The secondary mixing is carried out in a reaction vessel, and the rotation speed of the reaction vessel is 50 rpm to 500 rpm.

4. The method according to claim 1, characterized in that, The CO2 is introduced from the bottom of the reactor through an aeration disc, and the CO2 gas flow rate is 1L / min to 20L / min.

5. The method according to claim 1, characterized in that, The carbonation reaction takes 5 to 120 minutes.

6. The method according to claim 1, characterized in that, The steel slag is a solid waste generated during the converter steelmaking process, and the desulfurization ash is a solid waste generated by the semi-dry desulfurization process.

7. The method according to claim 1, characterized in that, The carbonated solid waste is used in the preparation of building materials, and the filtrate is treated to meet discharge standards.

8. A system for enhanced carbonation through synergistic coupling of multiple solid wastes, characterized in that, The system is adapted to the method according to any one of claims 1 to 7, the system comprising: Carbon fixation device (1) is used to contain steel slag-desulfurization ash mixture slurry and provide space for carbonation reaction; CO2 cylinder (2) is connected to the carbon fixation device (1) and is used to introduce CO2 gas into the carbon fixation device (1); The filter device (3) is connected to the carbon fixation device (1) and is used to filter and separate the slurry after the carbonation reaction to obtain carbonation solid waste (9) and carbonation filtrate (8). A planetary ball mill (7) is located upstream of the carbon fixation device (1) and is used to grind and mix steel slag (4) and desulfurization ash (5) to obtain a steel slag-desulfurization ash mixture. An electronic balance (6) is installed upstream of the planetary ball mill (7) for weighing and proportioning the steel slag (4) and desulfurization ash (5); A thermogravimetric analyzer (10) is installed downstream of the filter device (3) to perform thermogravimetric analysis on the carbonated solid waste (9) to calculate the degree of carbonation.

9. The system according to claim 8, characterized in that, The carbon fixation device (1) is equipped with an aeration plate at the bottom, and the CO2 gas cylinder (2) introduces CO2 gas into the solid waste mixture slurry in the carbon fixation device (1) through the aeration plate.

10. The system according to claim 8, characterized in that, The carbon fixation device (1) is equipped with a stirring device to ensure that the steel slag-desulfurization ash mixture slurry is fully contacted and reacted with CO2 gas.

Images