A method and system for preparing an alkaline residue-calcium sulfate composite activated product

Abstract

This disclosure relates to a method and system for preparing an alkaline slag-calcium sulfate composite activated product, belonging to the field of carbon fixation material preparation technology. The method includes: firstly, differentially mechanically activating alkaline slag and calcium sulfate to obtain pretreated powder; then, performing microwave-chemical coupling activation treatment; and finally, intermittent ultrasonic dynamic aging to obtain a precursor for carbon fixation filling materials. The system includes a dual-cavity graded ball mill module, a microwave-chemical coupling activation module, and an ultrasonic dynamic aging module connected in sequence. This application significantly improves the system's reactivity and structural uniformity through multi-stage synergistic activation, effectively solving technical defects such as salting out and cracking, and can greatly improve the carbon fixation rate and long-term mechanical strength, realizing the high-value utilization of bulk industrial solid waste and efficient carbon dioxide sequestration. This application has a simple process, low energy consumption, and strong controllability, and is suitable for large-scale industrial applications of carbon fixation filling in mines.

Description

Technical Field

[0001] This disclosure relates to the field of solid waste resource utilization and material pretreatment technology, specifically to a method and system for preparing an alkaline residue-calcium sulfate composite activation product. Background Technology

[0002] Alkali residue and sodium sulfate are two types of industrial solid waste produced in large quantities. They are rich in components such as calcium, sodium, and sulfate, and have the potential for synergistic utilization in mine backfilling and carbon dioxide mineralization and storage. However, when this composite system is used directly for carbon sequestration backfilling, it faces two major challenges: first, the low reactivity of the raw materials leads to a slow rate and low efficiency of mineralization and carbon sequestration; second, the easily soluble salt components in the system are prone to precipitation (salting out) during long-term service, which seriously degrades the structural stability and durability of the backfill.

[0003] Existing technologies mainly suffer from two limitations: one is the salt separation and recovery process centered on wet ball milling, multi-stage washing and screening, and metathesis, which aims to extract valuable components. This process is complex, consumes a lot of water and energy, and fails to specifically improve the overall reactivity and structural stability of the material for subsequent carbon fixation. The other type employs single or simple dual-activation methods (such as mechanical grinding alone or mechanical-chemical composites). While these methods can partially improve activity, the activation of multiphase heterogeneous systems like alkali residue-calcium sulfate is uneven and superficial, making it difficult to simultaneously achieve deep activation and fundamentally suppress salting-out problems. Furthermore, they often neglect the early structural stabilization control of the activated products.

[0004] Therefore, existing technologies lack a pretreatment method that can balance low water consumption, high activity enhancement, and long-term structural stability to efficiently convert alkaline slag-calcium sulfate into a high-quality precursor suitable for high-performance carbon fixation backfill materials. Summary of the Invention

[0005] The purpose of this disclosure is to provide a method and system for preparing an alkaline residue-calcium sulfate composite activated product, in order to solve the problems in the prior art.

[0006] To address the above problems, this application provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps:

[0007] S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate separately until the moisture content is no more than 1.0%. The mass ratio of the alkali residue and the calcium sulfate is 1.8:1 to 1:1.2. S2. Differentiated mechanical activation: The calcium sulfate obtained in step S1 is preferentially fed into the coarse grinding chamber of the dual-chamber classifying ball mill for preferential crushing. Then, the coarsely ground calcium sulfate and the alkaline residue obtained in step S1 are simultaneously fed into the fine grinding chamber of the dual-chamber classifying ball mill to jointly grind the mixture of the two to obtain composite activated powder. S3, Microwave-chemical coupling activation: The composite activated powder obtained in step S2 is placed in a microwave activation cavity for microwave preheating, and then an activator solution is sprayed in under stirring conditions. After the spraying is completed, microwave irradiation is continued and the material temperature is controlled at 45-55℃ to obtain a wet mixture. S4. Ultrasonic dynamic aging: The wet mixture obtained in step S3 is transferred to a closed aging device and aged at 20±3℃ and relative humidity not less than 85%; during the aging period, intermittent ultrasonic treatment is performed, the frequency of which is 25~45kHz, and it is started once every 10~14h to obtain the alkaline residue-calcium sodium sulfate composite activated product.

[0008] As a further improvement of this application, in step S1, the mass ratio of the alkali residue to calcium sulfate is 1.5:1.

[0009] As a further improvement of this disclosure, in step S2, the diameter of the grinding balls in the coarse grinding chamber is 12-16 mm, the ball-to-material ratio is 13:1-16:1, the rotation speed is 180-220 r / min, and the crushing time of calcium sulfate in the coarse grinding chamber is 30-40 min; the diameter of the grinding balls in the fine grinding chamber is 6-10 mm, the ball-to-material ratio is 14:1-17:1, the rotation speed is 260-300 r / min, and the combined grinding time is 45-55 min; the D90 of the obtained composite activated powder is not greater than 18 μm.

[0010] As a further improvement of this disclosure, in step S3, the concentration of the activator solution is 12% to 19%.

[0011] As a further improvement of this application and disclosure, the activator solution is at least one of calcium chloride solution and aluminum sulfate solution. Preferably, when it is a compound activator solution, the mass ratio of calcium chloride to aluminum sulfate is 1:1 to 3:1.

[0012] As a further improvement of this disclosure, in step S3, the activator solution is added in a segmented spraying manner, with the spraying rate gradually increasing from 0.5 mL / s to 1.2 mL / s.

[0013] As a further improvement of this disclosure, in step S4, the aging time is 3 to 6 days; the power of the ultrasonic treatment is 60 to 90 W, and the single treatment time is 4 to 6 minutes.

[0014] To achieve the above objectives, this application also provides a system for implementing any of the preparation methods described above, comprising a drying and metering module, a dual-cavity graded ball milling module, a microwave-chemical coupling activation module, an ultrasonic dynamic aging module, and a linkage control module connected in sequence. The linkage control module is electrically connected to the drying and metering module, the dual-cavity graded ball milling module, the microwave-chemical coupling activation module, and the ultrasonic dynamic aging module, respectively.

[0015] As a further improvement of this application, the microwave-chemical coupling activation module includes a microwave generator, a stirring mechanism, a spray nozzle assembly, and a temperature detection assembly.

[0016] As a further improvement to this application, the ultrasonic dynamic aging module includes a sealed curing tank, an ultrasonic transducer array, an intelligent spray water replenishment unit, and a temperature and humidity sensor.

[0017] The specific benefits of this application are as follows: This application utilizes a multi-stage synergistic process involving differentiated mechanical activation, microwave-chemical coupling activation, and ultrasonic dynamic aging to achieve low-water-consumption targeted activation and stabilization of the alkaline slag-calcium sulfate system, significantly improving the reactivity, structural uniformity, and long-term stability of the carbon-fixing backfill material precursor.

[0018] Dual-cavity classifying ball milling addresses the differences in physical properties between alkali residue and calcium sulfate, enabling preferential crushing of calcium sulfate and joint refinement of composite powders, significantly increasing specific surface area and optimizing particle size distribution, providing sufficient reaction interface for subsequent activation; microwave-chemical coupling activation utilizes microwave internal heating and non-thermal effects to enhance activator diffusion and mineral surface dissolution at low liquid volumes, precisely improving the intrinsic activity of the system and avoiding the problems of uneven heating and excessive energy consumption in conventional methods; intermittent ultrasonic dynamic aging promotes early structural rearrangement of wet mixtures and orderly growth of hydration products, stabilizes the high-humidity environment, and inhibits defects such as salting out and loosening from the source.

[0019] Compared to single activation or simple composite activation processes, this application's four-fold synergy significantly improves carbon sequestration rate and early and long-term mechanical strength. The filling material exhibits excellent durability with no salt precipitation after 180 days. It also enables high-value utilization of bulk industrial solid waste and efficient mineralization and storage of carbon dioxide. The process is simple, with low water consumption and strong controllability, making it suitable for large-scale application of carbon sequestration filling in mines. It has both environmental benefits and practical engineering value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system provided in Example 5 for implementing the preparation method of the alkaline residue-calcium sulfate composite activated product.

[0021] In the diagram: 1. Drying and metering module; 2. Dual-cavity graded ball milling module; 3. Microwave-chemical coupling activation module; 4. Ultrasonic dynamic aging module; 5. Linkage control module. Detailed Implementation

[0022] As can be seen from the background art, in order to solve the technical problems encountered in the treatment of two major solid wastes, alkali residue and calcium sulfate, this application provides a method for preparing an alkali residue-calcium sulfate composite activated product, including the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate separately until the moisture content is no more than 1.0%. The mass ratio of the alkali residue and the calcium sulfate is 1.8:1 to 1:1.2. S2. Differentiated mechanical activation: The calcium sulfate obtained in step S1 is preferentially fed into the coarse grinding chamber of the dual-chamber classifying ball mill for preferential crushing. Then, the coarsely ground calcium sulfate and the alkaline residue obtained in step S1 are simultaneously fed into the fine grinding chamber of the dual-chamber classifying ball mill. The mixture of the two is jointly ground to obtain a composite activated powder with a specific surface area of ​​450-620 m² / kg. S3. Microwave-chemical coupling activation: The composite activated powder obtained in step S2 is placed in a microwave activation chamber and preheated at a microwave power of 150-250W for 6-9 minutes. Then, an activator solution is sprayed in under stirring conditions of 30-50 r / min. The amount of activator solution added is 3%-7% of the total mass of the composite activated powder. After spraying, microwave irradiation is continued at a microwave power of 350-480W for 12-18 minutes, and the temperature of the composite activated powder is controlled at 45-55℃ to obtain a wet mixture. S4. Ultrasonic dynamic aging: The wet mixture obtained in step S3 is transferred to a closed aging device and aged at 20±3℃ and relative humidity not less than 85%; during the aging period, intermittent ultrasonic treatment is performed, the frequency of which is 25~45kHz, and it is started once every 10~14h to obtain the alkaline residue-calcium sodium sulfate composite activated product.

[0023] Preferably, the activated pretreatment product is used to prepare carbon dioxide mineralization carbon fixation filling material.

[0024] In an optional implementation, in step S1, the mass ratio of the alkali residue to sodium sulfate is 1.5:1.

[0025] In an optional implementation, in step S2, the diameter of the grinding balls in the coarse grinding chamber is 12–16 mm, the ball-to-material ratio is 13:1–16:1, the rotation speed is 180–220 r / min, and the crushing time of calcium sulfate in the coarse grinding chamber is 30–40 min; the diameter of the grinding balls in the fine grinding chamber is 6–10 mm, the ball-to-material ratio is 14:1–17:1, the rotation speed is 260–300 r / min, and the combined grinding time is 45–55 min; the D90 of the resulting composite activated powder is not greater than 18 μm. Preferably, the coarse grinding chamber uses zirconia grinding balls, and the fine grinding chamber uses silicon carbide grinding balls.

[0026] In an optional implementation, in step S3, the concentration of the activator solution is 12% to 19%. Preferably, the amount of the activator solution is 4.5% to 5.5% of the total mass of the composite activated powder.

[0027] In an optional embodiment, the activator solution is at least one of calcium chloride solution and aluminum sulfate solution. Preferably, when it is a compound activator solution, the mass ratio of calcium chloride to aluminum sulfate is 1:1 to 3:1.

[0028] In an optional implementation, in step S3, the activator solution is added in stages, with the injection rate gradually increasing from 0.5 mL / s to 1.2 mL / s. Preferably, the microwave activation cavity is equipped with an infrared temperature sensor linked to the microwave generator to maintain the temperature of the composite activated powder stable at 45–55°C.

[0029] In an optional implementation, in step S4, the aging time is 3–6 days; the ultrasonic treatment power is 60–90W, and the single treatment time is 4–6 minutes. Preferably, the sealed aging device is equipped with a humidity sensor and a spray water replenishment unit, which automatically replenishes water when the relative humidity is lower than a set value, and the relative humidity fluctuation during the aging process is controlled within 5%.

[0030] This application also provides a system for implementing the preparation method of the alkaline residue-calcium sodium sulfate composite activated product as described in any of the above claims, comprising a drying and metering module, a dual-cavity graded ball milling module, a microwave-chemical coupling activation module, an ultrasonic dynamic aging module, and a linkage control module connected in sequence. The linkage control module is electrically connected to the drying and metering module, the dual-cavity graded ball milling module, the microwave-chemical coupling activation module, and the ultrasonic dynamic aging module, respectively. Preferably, the drying and metering module includes a raw material drying unit and a metering and feeding unit.

[0031] In an optional implementation, the microwave-chemical coupling activation module includes a microwave generator, a stirring mechanism, a spray nozzle assembly, and a temperature detection assembly. Preferably, the microwave-chemical coupling activation module further includes a waveguide coupler, a feed airlock valve, and a discharge airlock valve.

[0032] In an optional implementation, the ultrasonic dynamic aging module includes a sealed curing tank, an ultrasonic transducer array, an intelligent spray water replenishment unit, and a temperature and humidity sensor. Preferably, the ultrasonic dynamic aging module further includes a double-layer insulation structure, an exhaust filter valve, a pressure monitoring unit, and an online sampling port.

[0033] Based on the above technical solution, this application utilizes a multi-stage synergistic effect of physical modification, energy-driven action, chemical activation, and structural stabilization to perform low-water-consumption targeted activation and stabilization treatment on the alkali residue-calcium sulfate composite system, as detailed below: Differential mechanical activation (S2) lays the physical foundation: Addressing the differences in hardness and grindability between alkali residue and sodium sulfate, a dual-chamber staged ball mill is employed. First, in the coarse grinding chamber, large-diameter grinding balls at a lower speed are used to preferentially crush the harder sodium sulfate, disrupting its crystal structure. Then, the coarsely ground sodium sulfate and alkali residue are combined and finely ground in the fine grinding chamber using small-diameter grinding balls at a higher speed. This process significantly increases the specific surface area of ​​the materials (450–620 m²). 2 / kg), generating a large number of lattice defects and fresh surfaces, and also achieving uniform mixing of the two phases, creating a sufficient and uniform physical interface for subsequent reactions.

[0034] Microwave-chemical coupling activation (S3) achieves deep synergistic activation: High specific surface area composite powders are placed in a microwave field. The internal heating effect of microwaves rapidly and uniformly raises the internal temperature of the material to 45–55°C, overcoming the thermal gradient problem of traditional heating methods. Under the combined action of this temperature field and mechanical stirring, low-volume activator solutions (such as calcium chloride and aluminum sulfate) are injected in stages. Microwave energy significantly accelerates the diffusion rate and penetration depth of activator ions between powder particles; on the other hand, its non-thermal effect may locally disrupt the mineral surface structure, exposing more active sites. The chemical activator directionally dissolves the inert layer on the particle surface, promotes the dissolution of active ions such as calcium and magnesium, and reacts with sulfate and aluminate ions in the system to generate early hydration products (such as ettringite). The physical energy drive of microwaves and the chemical modification of chemical activators are deeply coupled in this step, achieving uniform and efficient activation of composite powders with extremely low water consumption.

[0035] Ultrasonic dynamic aging (S4) achieves structural stabilization: The microwave-chemically activated wet mix is ​​placed in a closed, temperature- and humidity-controlled environment for aging. During this process, intermittent ultrasonic treatment with specific parameters is applied. The localized high pressure, high temperature, and intense microjets generated by the ultrasonic cavitation effect further promote the uniform dispersion of the components within the wet mix, break down any encapsulation layers that may form, and accelerate the nucleation and growth of early hydration / reaction products. Simultaneously, the mechanical energy of ultrasound helps induce the reaction products to form a more ordered and denser microstructure. This "dynamic" aging method, compared to static curing, effectively optimizes the early structure formation process, significantly improves the structural uniformity and stability of the product, thereby fundamentally inhibiting the precipitation (salting out) of easily soluble salt components in the later stages and enhancing the long-term mechanical properties of the final filling.

[0036] In summary, this application forms a complete dry pretreatment process chain through the sequential connection and functional synergy of the three steps S2 to S4, ultimately obtaining an alkaline slag-calcium sulfate composite activation product with high reactivity and strong structural stability, which is specifically used to prepare high-performance carbon dioxide mineralization carbon fixation filling materials.

[0037] The technical solutions of this disclosure will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0038] To make the above-mentioned objectives, features and advantages of this disclosure more apparent and understandable, the disclosure will be further described in detail below with reference to specific embodiments.

[0039] It should be noted that the carbon fixation rate in the following examples refers to the percentage of carbon fixed by the alkaline slag-calcium sulfate composite activation product during the subsequent carbon dioxide mineralization and carbon fixation backfilling process, calculated by measuring the carbonate content in the backfill. The 3-day compressive strength and 180-day compressive strength refer to the compressive strength of the backfill after 3 days and 180 days of curing, respectively, measured using a universal testing machine. Salt precipitation refers to whether salt precipitation occurs on the surface of the backfill, determined through visual observation and XRD analysis.

[0040] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0041] Example 1 This embodiment provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and sodium sulfate to a moisture content of 0.9% respectively, and weigh 360g of alkali residue and 200g of sodium sulfate at a mass ratio of 1.8:1.

[0042] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 12mm diameter zirconia grinding balls at a ball-to-material ratio of 13:1. The mixture was crushed at 180r / min for 40min. Subsequently, the coarsely ground calcium sulfate and 360g of alkaline residue were fed into the fine grinding chamber, which contained 6mm diameter silicon carbide grinding balls at a ball-to-material ratio of 14:1. The mixture was then combined and ground at 260r / min for 55min, yielding a specific surface area of ​​approximately 450m². 2 Composite activated powder with a density of 17μm and a density of 17μm per kg.

[0043] S3. Microwave-chemical coupling activation: The above-mentioned composite activated powder is placed in a microwave activation chamber and preheated at 150W power for 9 minutes. Then, under stirring at 30r / min, a 12% calcium chloride solution is sprayed in, with the amount of solution added being 3% of the total mass of the powder. After the spraying is completed, irradiation continues at 350W power for 18 minutes, and the material temperature is controlled at 45℃ to obtain a wet mixture.

[0044] S4. Ultrasonic Dynamic Aging: The wet mixture from step S3 was transferred to a closed aging device and aged for 6 days at 17℃ and 85% relative humidity. During aging, ultrasonic treatment was initiated every 14 hours with parameters of frequency 25kHz, power 60W, and single treatment time of 6 minutes to obtain the alkali slag-calcium sulfate composite activated product. The obtained alkali slag-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 68%. The resulting filling material exhibited a 3-day strength of 2.6 MPa and a 180-day strength of 5.3 MPa, with no salt precipitation.

[0045] Example 2 This embodiment provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.7% respectively, and weigh 200g of alkali residue and 240g of calcium sulfate at a mass ratio of 1:1.2.

[0046] S2. Differentiated Mechanical Activation: 240g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 16mm diameter zirconia grinding balls at a ball-to-material ratio of 16:1, and crushed at 220r / min for 30min. Subsequently, the coarsely ground calcium sulfate and 200g of alkaline residue were fed into the fine grinding chamber, which contained 10mm diameter silicon carbide grinding balls at a ball-to-material ratio of 17:1, and jointly ground at 300r / min for 45min, yielding a specific surface area of ​​approximately 620m². 2 Composite activated powder with a density of / kg and a D90 of 10μm.

[0047] S3. Microwave-chemical coupling activation: The above-mentioned composite activated powder is placed in a microwave activation chamber and preheated at 250W power for 6 minutes. Then, under stirring at 50r / min, a 19% aluminum sulfate solution is sprayed in a segmented spraying method (the rate is increased from 0.5mL / s to 1.2mL / s). The amount of solution added is 7% of the total mass of the powder. After the spraying is completed, the powder is irradiated for another 12 minutes at 480W power, and the material temperature is controlled at 55℃ to obtain a wet mixture.

[0048] S4. Ultrasonic Dynamic Aging: The wet mixture obtained above was transferred to a closed aging device and aged for 3 days at 23℃ and 90% relative humidity. During the aging period, ultrasonic treatment was initiated every 10 hours with parameters of frequency 45kHz, power 90W, and single treatment time of 4min, to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and found to have a carbon fixation rate of 72%, and the strength of the prepared filling material was 2.9MPa after 3 days and 5.8MPa after 180 days, with no salt precipitation.

[0049] Example 3 This embodiment provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0050] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0051] S3. Microwave-chemical coupling activation: The above-mentioned composite activated powder was placed in a microwave activation chamber and preheated at 200W power for 7.5 min. Then, under stirring at 40 r / min, a 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed in using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, the powder was irradiated for another 15 min at 415W power, and the material temperature was controlled at 50℃ to obtain a wet mixture.

[0052] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and found to have a carbon fixation rate of 76%. The prepared filling material had a 3-day strength of 3.2MPa and a 180-day strength of 6.2MPa, and no salt precipitation was observed.

[0053] Example 4 This embodiment provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0054] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0055] S3. Microwave-chemical coupling activation: The above-mentioned composite activated powder is placed in a microwave activation chamber and preheated at 200W power for 7.5min. Then, under stirring at 40r / min, a 15% calcium chloride aqueous solution is sprayed in using a segmented spraying method (the rate is increased from 0.8mL / s to 1.0mL / s). The amount of solution added is 5% of the total mass of the powder. After the spraying is completed, irradiation is continued at 415W power for 15min, and the material temperature is controlled at 50℃ to obtain a wet mixture.

[0056] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, yielding an alkaline slag-calcium sulfate composite activated product. The obtained alkaline slag-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 72%, a 3-day compressive strength of 3.0MPa, a 180-day compressive strength of 5.9MPa, and no salt precipitation.

[0057] Comparative Example 1-1 (without ultrasonic-assisted aging) Compared with Example 3, this comparative example omits the step of ultrasound-assisted aging, while the other steps are the same as in Example 3, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0058] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0059] S3. Microwave-chemical coupling activation: The powder is placed in a microwave activation chamber and preheated at 200W for 7.5 min. Then, under stirring at 40 r / min, a 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) is sprayed in using a segmented spraying method (rate increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added is 5% of the total mass of the powder. After the spraying is completed, the powder is irradiated for another 15 min at 415W, and the material temperature is controlled at 50℃.

[0060] S4. Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and found to have a carbon fixation rate of 68%; the 3-day strength of the filling body was 2.6 MPa, and the 180-day strength was 5.3 MPa; no salt precipitation was observed after 180 days.

[0061] The only difference between Comparative Example 1-1 and Example 3 is that the "intermittent ultrasonic treatment" in step S4 was omitted, and only conventional static aging under the same temperature and humidity conditions was performed. Performance test results showed that the carbon fixation rate of the product obtained in Comparative Example 1-1 was 68%, and the compressive strength of the prepared filling material was 2.6 MPa after 3 days and 5.3 MPa after 180 days; while the corresponding data for Example 3 were 76%, 3.2 MPa, and 6.2 MPa, respectively. There were significant differences between the two in carbon fixation rate, early strength, and long-term strength (increased by approximately 11.8%, 23.1%, and 17.0%, respectively). Although no salting out was observed in either after 180 days, the overall improvement in strength indicators suggests that ultrasonic treatment is not an optional auxiliary step. The comparative results demonstrate that, based on the completion of mechanical activation and microwave-chemical coupling activation, introducing intermittent ultrasonic treatment with specific parameters can further optimize the microscopic processes of wet mixtures during aging: ultrasonic cavitation and microfluidic effects promote further uniform dispersion of activator ions and material particles, accelerate the nucleation and growth of early hydration / reaction products, and may induce the formation of more ordered and denser microstructures. This not only enhances the reactivity of the final product (manifested as a higher carbon fixation rate) but also significantly enhances the mechanical properties of the fillers prepared from it. Therefore, the "ultrasonic dynamic aging" defined in step S4 is an indispensable part of the multi-stage synergistic process of "mechanical activation-microwave-chemical coupling activation-ultrasonic dynamic aging" in this application.

[0062] Comparative Examples 1-2 (without ultrasonic-assisted aging, and with a change in mechanical activation method) Compared with Comparative Example 1-1, this comparative example uses a different mechanical activation method, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, and mix the two to obtain a mixture.

[0063] S2. Planetary ball mill mechanical activation: Put all 500g of the mixture into a planetary ball mill, select agate grinding balls with a diameter of 10mm, and the ball-to-material ratio is 16:1. Grind continuously at a speed of 260r / min for 80min to obtain composite activated powder.

[0064] S3. Microwave-chemical coupling activation: The above-mentioned composite activated powder was placed in a microwave activation chamber and preheated at 200W power for 7.5 min. Then, under stirring at 40 r / min, a 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed in using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, the powder was irradiated for another 15 min at 415W power, and the material temperature was controlled at 50℃.

[0065] S4. Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and found to have a carbon fixation rate of 58%; the 3-day strength of the filling body was 2.2 MPa, and the 180-day strength was 4.2 MPa; no salt precipitation was observed after 180 days.

[0066] A comprehensive comparison of Comparative Example 1-1, Comparative Example 1-2, and Example 3 shows that: A direct comparison between Comparative Example 1-1 (dual-cavity graded ball milling combined with microwave-chemical activation, without ultrasound) and Example 3 has shown that ultrasonic dynamic aging (step S4) plays a key role in further improving carbon fixation rate (from 68% to 76%) and mechanical strength (180-day strength from 5.3 MPa to 6.2 MPa).

[0067] However, the product performance (carbon fixation rate 58%, 180-day strength 4.2 MPa) of Comparative Examples 1-2 (planetary ball milling combined with microwave-chemical activation, without ultrasound) was not only far lower than that of Example 3, but also significantly lower than that of Comparative Example 1-1 (also without ultrasound, but using dual-chamber staged ball milling). This gap highlights the core value of step S2, "differentiated mechanical activation". The dual-chamber staged ball mill is not a simple grinding process; its differentiated design of "prioritizing the crushing of calcium sulfate in the coarse grinding chamber and combining grinding in the fine grinding chamber" specifically addresses the problem of large differences in hardness and grindability between alkaline slag and calcium sulfate, efficiently producing composite powders with high specific surface area and optimized particle size distribution (specific surface area 450-620 m²). 2 / kg, D90≤18μm), providing a sufficient and uniform reaction interface for subsequent microwave-chemical activation. Planetary ball milling cannot achieve this effect, resulting in insufficient initial reaction sites. Even after undergoing the same S3 and S4 steps, the final performance is "inherently deficient".

[0068] Comparative Example 2-1 (without microwave-assisted chemical activation) The difference between this comparative example and Example 3 is that the microwave step in step S3 is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0069] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0070] S3. Chemical activation: A 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed onto the above composite activated powder using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, a wet mixture was obtained.

[0071] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5 minutes to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 61%. The compressive strength of the prepared filling material was 2.4MPa after 3 days and 4.5MPa after 180 days, with no salt precipitation after 180 days.

[0072] A comparison of Comparative Example 2-1 and Example 3 shows that the carbon fixation rate (61%) and 180-day compressive strength (4.5 MPa) of Comparative Example 2-1 (without microwave) are significantly lower than those of Example 3 (76% carbon fixation rate, 6.2 MPa 180-day compressive strength). This difference directly demonstrates the crucial role of microwave irradiation in step S3. The internal heating effect provided by microwaves enables rapid and uniform internal heating of the material at a generally low temperature (45-55°C), effectively overcoming the problem of uneven heat transfer in dry systems. This not only significantly accelerates the diffusion rate of activator ions into the material particles and enhances surface chemical reactions, but may also locally disrupt the mineral lattice through hotspot effects, exposing more active sites. Therefore, microwaves are not simply a heating method, but a core driving force for achieving deep, efficient, and uniform chemical activation at low liquid volumes, and an indispensable link in improving the reactivity and mechanical properties of the final product.

[0073] Comparative Example 2-2 (no microwave-assisted chemical activation, and no ultrasonic assistance). The difference between this comparative example and Comparative Example 2-1 is that the ultrasound step in step S4 is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0074] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0075] S3. Chemical activation: A 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed onto the above composite activated powder using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, a wet mixture was obtained.

[0076] S4. Aging: The obtained wet mixture is transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity to obtain the alkali residue-calcium sulfate composite activated product. The obtained alkali residue-calcium sulfate composite activated product was tested and found to have a carbon fixation rate of 58%. The compressive strength of the prepared filling material was 2.2 MPa after 3 days and 4.2 MPa after 180 days. No salt precipitation was observed after 180 days.

[0077] As can be seen from the comparison of Comparative Example 2-2 with Comparative Example 2-1 and Example 3, the performance of Comparative Example 2-2 (no microwave, no ultrasound) (carbon fixation rate 58%, 180-day compressive strength 4.2 MPa) is not only much lower than that of Example 3 (carbon fixation rate 76%, 180-day compressive strength 6.2 MPa), but also lower than that of Comparative Example 2-1 (no microwave, with ultrasound, carbon fixation rate 61%, 180-day compressive strength 4.5 MPa).

[0078] Comparative Examples 2-2 and 2-1 both used no microwaves; the only difference was that Comparative Example 2-1 employed ultrasonic aging. The slight improvement in carbon fixation rate and compressive strength in Comparative Example 2-1 confirms the role of ultrasound in optimizing the structure during aging. However, the overall performance levels of both remained relatively low, indicating that microwave activation is also a key factor in improving performance.

[0079] Comparative Examples 2-1 and Example 3 both employed ultrasonic aging, the only difference being that Example 3 introduced microwave-chemical coupling activation. The significant leap in carbon fixation rate and strength in Example 3 (approximately 24.6% and 37.8% increases, respectively) strongly demonstrates the core value of microwaves: their internal heating and non-thermal effects can overcome the limitations of mass transfer and reaction kinetics in conventional stirring and mixing with extremely low liquid phase dosages, achieving deep, rapid, and uniform action between the activator and material particles, thereby fundamentally and significantly enhancing the reactivity of the system. Therefore, microwaves are not merely an auxiliary means, but a key driving step in achieving the high-performance goals of this application; their synergy with ultrasound constitutes a complete and efficient chain from activation to stabilization.

[0080] Comparative Examples 2-3 (no microwave-assisted chemical activation, and the mechanical activation method was changed). The difference between this comparative example and Comparative Example 2-1 is that the mechanical activation method has been changed, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, and mix the two to obtain a mixture.

[0081] S2. Planetary ball mill mechanical activation: Put all 500g of the mixture into a planetary ball mill, select agate grinding balls with a diameter of 10mm, and the ball-to-material ratio is 16:1. Grind continuously at a speed of 260r / min for 80min to obtain composite activated powder.

[0082] S3. Chemical activation: A 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed onto the above composite activated powder using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, a wet mixture was obtained.

[0083] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, yielding an alkaline slag-calcium sulfate composite activated product. The obtained alkaline slag-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 52%. The compressive strength of the prepared filling material was 1.9MPa after 3 days and 3.8MPa after 180 days, with slight salting out after 180 days.

[0084] A comparison of Comparative Example 2-3 and Comparative Example 2-1 shows that the performance of Comparative Example 2-3 (planetary ball milling + chemical + ultrasonic, no microwave) (carbon fixation rate 52%, 180-day strength 3.8 MPa, slight salting out) is significantly lower than that of Comparative Example 2-1 (dual-chamber staged ball milling + chemical + ultrasonic, no microwave, 61%, 4.5 MPa, no salting out). Both examples are identical in all steps except for the mechanical activation method (S2), indicating that the dual-chamber staged ball mill has irreplaceable technical advantages. Its targeted design of "prioritizing coarse grinding to crush calcium sulfate and combined fine grinding to optimize particle size" can more efficiently prepare composite powders with high specific surface area, reasonable particle size distribution, and uniform two-phase mixing compared to the simple mixing and grinding of planetary ball milling. This creates a better initial reaction interface and mass transfer conditions for subsequent chemical activation, which is the basis for obtaining higher activity and stability.

[0085] Example 3, building upon the high-quality materials used in Comparative Example 2-1 (dual-cavity classifying ball mill), further introduced microwave-chemical coupling activation. The internal heating effect of microwaves significantly enhanced the reaction kinetics, resulting in a leap in final performance: the carbon fixation rate increased from 61% to 76%, the 180-day compressive strength increased from 4.5 MPa to 6.2 MPa, and there was no salt precipitation, highlighting the key driving role of the microwave step.

[0086] Comparisons of Comparative Examples 2-3, 2-2, and Example 3 show that mechanical activation via dual-cavity graded ball milling is the cornerstone of building a high-performance system, and microwave-chemical coupling is the key engine for breaking through the upper limit of activity. The two, together with ultrasonic dynamic aging, synergistically improve the performance of the composite activated product.

[0087] Comparative Examples 2-4 (no microwave-assisted chemical activation, and the mechanical activation method was changed). The difference between this comparative example and Comparative Example 2-1 is that the mechanical activation method has been changed, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, and mix the two to obtain a mixture.

[0088] S2. Mechanical activation of the vibratory mill: Put all 500g of the mixture into the vibratory mill, set the amplitude to 5mm and the vibration frequency to 32Hz, and grind for 60min to obtain the composite activated powder.

[0089] S3. Chemical activation: A 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) was sprayed onto the above composite activated powder using a segmented spraying method (the rate was increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added was 5% of the total mass of the powder. After the spraying was completed, a wet mixture was obtained.

[0090] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, yielding an alkaline slag-calcium sulfate composite activated product. The obtained alkaline slag-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 48%. The compressive strength of the prepared filling material was 1.7MPa after 3 days and 3.5MPa after 180 days. Salt precipitation occurred after 180 days.

[0091] The performance of Comparative Examples 2-4 (vibratory milling + chemical + ultrasonic, no microwave) (carbon fixation rate 48%, 180-day strength 3.5 MPa, salting out) was not only significantly lower than that of Example 3 (dual-cavity graded ball milling + microwave-chemical + ultrasonic, 76%, 6.2 MPa, no salting out), but also significantly inferior to Comparative Example 2-1 (dual-cavity graded ball milling + chemical + ultrasonic, no microwave, 61%, 4.5 MPa, no salting out). Specifically: A direct comparison between Comparative Examples 2-4 and 2-1 (both without microwaves, both with ultrasound) shows that even with identical subsequent processing steps, the product obtained using the mechanical activation method of vibration milling exhibits inferior carbon fixation activity, final strength, and long-term stability (resistance to salt precipitation) compared to the method using dual-cavity staged ball milling. This further confirms the unique value of the differentiated mechanical activation defined in step S2—its customized grinding strategy tailored to the differences in physical properties between alkali slag and calcium sulfate is an indispensable physical basis for constructing precursors with high reactivity and high structural stability. The difference between Comparative Example 2-1 and Example 3 highlights the decisive role of "microwave-chemical coupling activation" (S3) in significantly exceeding performance limits, provided that a high-quality material foundation is already available.

[0092] Therefore, the technical effect of this application depends on the deep synergy and sequential optimization of the three stages of "differentiated mechanical activation", "microwave-chemical coupling activation" and "ultrasonic dynamic aging". The absence of any stage or the replacement with conventional methods will lead to a significant decrease in performance.

[0093] Comparative Example 3-1 (without chemical activation) The difference between this comparative example and Example 3 is that the step of adding chemical agents for activation in step S3 is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0094] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0095] S3. Microwave activation: The above-mentioned composite activated powder is placed in a microwave activation chamber and preheated at 200W power for 7.5 minutes; then irradiated at 415W power for 15 minutes, with the material temperature controlled at 50℃, to obtain microwave activated material.

[0096] S4. Ultrasonic Dynamic Aging: The obtained microwave-activated material was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, yielding an alkaline residue-calcium sulfate composite activated product. The obtained alkaline residue-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 51%. The compressive strength of the prepared filling material was 1.9MPa after 3 days and 3.6MPa after 180 days. Slight salt precipitation occurred after 180 days.

[0097] The performance of Comparative Example 3-1 (51%, 3.6 MPa, slight salting out) contrasts sharply with that of Example 3 (76%, 6.2 MPa, no salting out). This demonstrates that while physical methods such as mechanical refining, microwave heating, and ultrasonic perturbation can improve the material state to some extent, they cannot directionally dissolve the surface inert layer, promote the dissolution of active ions, and induce early beneficial chemical reactions like chemical activators. The chemical activation step (S3) is the core chemical process for achieving deep activation of the system, enhancing its inherent reactivity, and pre-constructing a stable structure to suppress salting out. Without this step, the final performance of the product will be significantly reduced, and the salting out problem cannot be eradicated, thus strongly demonstrating the indispensability of chemical activation.

[0098] Comparative Example 3-2 (No chemical excitation, no ultrasound) The difference between this comparative example and Comparative Example 3-1 is that the ultrasound step in step S4 is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1.

[0099] S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1, and crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline slag were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1, and jointly ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 Composite activated powder with a density of / kg and a D90 of 15μm.

[0100] S3. Microwave activation: The above-mentioned composite activated powder is placed in a microwave activation chamber and preheated at 200W power for 7.5 minutes; then irradiated at 415W power for 15 minutes, with the material temperature controlled at 50℃, to obtain microwave activated material.

[0101] S4. Aging: The obtained microwave-activated material was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity to obtain an alkaline residue-calcium sulfate composite activated product. The obtained alkaline residue-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 48%. The compressive strength of the prepared filling material was 1.8 MPa after 3 days and 3.3 MPa after 180 days. Salt precipitation occurred after 180 days.

[0102] A stepwise comparison of Comparative Example 3-2 (48%, 3.3 MPa, salting out), Comparative Example 3-1 (51%, 3.6 MPa, slight salting out), and Example 3 (76%, 6.2 MPa, no salting out) clearly reveals the synergistic effect of chemical activation and ultrasonic aging: chemical activation (S3) is the core of enhancing the intrinsic reactivity of the system, and its effect is dominant (comparing 3-2 and 3-1, the main difference lies in the presence or absence of chemical activation); while ultrasonic dynamic aging (S4) is a key auxiliary means to further optimize the microstructure, increase density, and enhance long-term stability on the basis of chemical activation (comparing 3-1 and 3-2, the addition of ultrasound slightly improves performance and reduces salting out).

[0103] Furthermore, as shown in Comparative Example 3-1, even with ultrasonic assistance, the performance upper limit remains very low without chemical activation, and the salting-out problem cannot be eradicated. This demonstrates that chemical activation and ultrasonic aging are not simply additive, but rather a deep synergy between the "primary" and "secondary" components: chemical activation creates the basis for the active reaction, while ultrasonic aging consolidates and strengthens the structure formed on this basis. The combination of the two, along with mechanical activation and microwave irradiation, achieves the excellent and stable comprehensive effect of this application.

[0104] Comparative Example 4-1 (Undifferentiated mechanical activation) The difference between this comparative example and Example 3 is that the differentiated mechanical activation step is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, and mix the two to obtain a mixture.

[0105] S3. Microwave-chemical coupling activation: The above mixture is placed in a microwave activation chamber and preheated at 200W power for 7.5 min. Then, under stirring at 40 r / min, a 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) is sprayed in using a segmented spraying method (rate increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added is 5% of the total mass of the powder. After the spraying is completed, irradiation is continued at 415W power for 15 min, and the material temperature is controlled at 50℃ to obtain a wet mixture.

[0106] S4. Ultrasonic Dynamic Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity. During the aging period, ultrasonic treatment was initiated every 12 hours with parameters of frequency 35kHz, power 75W, and single treatment time of 5min, yielding an alkaline slag-calcium sulfate composite activated product. The obtained alkaline slag-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 53%. The compressive strength of the prepared filling material was 2.0MPa after 3 days and 3.8MPa after 180 days, with no significant salt precipitation after 180 days.

[0107] The performance of Comparative Example 4-1 (53%, 3.8 MPa) differs significantly from that of Example 3 (76%, 6.2 MPa). This demonstrates that step S2, "differentiated mechanical activation," in the technical solution of this application is the prerequisite and foundation for all subsequent efficient treatments. Without mechanical activation, coarse particulate materials, even with microwave and ultrasonic treatments, cannot create a sufficient reaction interface and a homogeneous system, resulting in low efficiency of the chemical activator and microwave energy, and preventing deep activation. Therefore, mechanical activation is not an optional step, but a necessary pre-process for constructing a highly active composite system, enabling subsequent microwave-chemical coupling and ultrasonic treatments to achieve maximum efficiency.

[0108] Comparative Example 4-2 (no differential mechanical activation, and no ultrasound assistance) The difference between this comparative example and Comparative Example 4-1 is that the ultrasound step is omitted, as detailed below: This comparative example provides a method for preparing an alkaline residue-calcium sulfate composite activated product, comprising the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, and mix the two to obtain a mixture.

[0109] S3. Microwave-chemical coupling activation: The above mixture is placed in a microwave activation chamber and preheated at 200W power for 7.5 min. Then, under stirring at 40 r / min, a 15.5% calcium chloride and aluminum sulfate compound solution (mass ratio 2:1) is sprayed in using a segmented spraying method (rate increased from 0.8 mL / s to 1.0 mL / s). The amount of solution added is 5% of the total mass of the powder. After the spraying is completed, irradiation is continued at 415W power for 15 min, and the material temperature is controlled at 50℃ to obtain a wet mixture.

[0110] S4. Aging: The obtained wet mixture was transferred to a closed aging device and aged for 4.5 days at 20℃ and 88% relative humidity to obtain the alkaline residue-calcium sulfate composite activated product. The obtained alkaline residue-calcium sulfate composite activated product was tested and showed a carbon fixation rate of 50%. The compressive strength of the prepared filling material was 1.8 MPa after 3 days and 3.5 MPa after 180 days, with no significant salt precipitation after 180 days.

[0111] The comparison between Comparative Example 4-2 (50%, 3.5 MPa), Comparative Example 4-1 (53%, 3.8 MPa), and Example 3 (76%, 6.2 MPa) corroborates the synergistic enhancement relationship between differentiated mechanical activation and ultrasonic treatment: Both Comparative Examples 4-2 and 4-1 were not mechanically activated, and their performance was low. Comparative Example 4-1 was slightly better due to the presence of ultrasound, indicating that the auxiliary optimization effect of ultrasound is limited when the material basis is weak (coarse particles).

[0112] Both Comparative Example 4-1 and Example 3 involve ultrasound, but Example 3, due to prior differentiated mechanical activation, exhibits a significant performance leap. This demonstrates that the high efficiency of ultrasonic dynamic aging depends on the high-quality material base (high specific surface area, reasonable particle size distribution, and uniform mixing) created by differentiated mechanical activation. Mechanical activation provides an optimized, high-quality preform for ultrasound; conversely, without this preform, the ultrasonic effect is greatly reduced. Therefore, there is a profound sequential dependency and synergistic effect between differentiated mechanical activation (S2) and ultrasonic dynamic aging (S4). The combination of these two processes, linked with the microwave-chemical steps, achieves a high-performance, complete process chain.

[0113] Comparative Example 5-1 (Single mechanical activation: dual-cavity staged ball milling) The difference between this comparative example and Example 3 is that steps S3 and S4 have been removed, while the preceding steps remain the same as in Example 3: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1. S2. Differentiated Mechanical Activation: 200g of calcium sulfate was fed into the coarse grinding chamber of a dual-chamber classifying ball mill, which contained 14mm diameter zirconia grinding balls at a ball-to-material ratio of 14.5:1. The mixture was crushed at 200r / min for 35min. Subsequently, the coarsely ground calcium sulfate and 300g of alkaline residue were fed into the fine grinding chamber, which contained 8mm diameter silicon carbide grinding balls at a ball-to-material ratio of 15.5:1. The mixture was then combined and ground at 280r / min for 50min, yielding a specific surface area of ​​approximately 550m². 2 A composite activated product of alkali residue and calcium sulfate was obtained with a density of / kg and a D90 of 15μm. Subsequently, steps S3 (microwave-chemical coupling activation) and S4 (ultrasonic dynamic aging) were skipped, and the obtained composite activated product was directly used for the preparation and performance testing of subsequent carbon dioxide mineralization carbon fixation filling materials.

[0114] Test results showed that the carbon fixation rate was only 32%, the 3-day compressive strength of the prepared filling was 1.1 MPa, the 180-day compressive strength was 2.0 MPa, and slight salt precipitation appeared on the surface of the test block after the 180-day curing period.

[0115] Compared with Example 3 (76% carbon fixation rate, 3-day strength of 3.2 MPa, 180-day strength of 6.2 MPa and no salting out), the performance indicators of Comparative Example 1 decreased significantly and salting out occurred.

[0116] The comparative results clearly demonstrate that mechanical activation alone (S1+S2) cannot achieve the comprehensive technical effects of high carbon fixation rate, high mechanical properties, and long-term structural stability (no salt precipitation) achieved by the synergistic treatment of the entire process of "mechanical activation - microwave-chemical coupling activation - ultrasonic dynamic aging" in this application. This highlights the necessity and inventive contribution of steps S3 (microwave-chemical coupling activation) and S4 (ultrasonic dynamic aging) in solving the technical problems of this application.

[0117] Comparative Example 5-2 (Single mechanical activation: planetary ball mill) This comparative example is used to investigate the effects of changing the mechanical activation method and omitting subsequent key steps.

[0118] S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 250g of alkali residue and 250g of calcium sulfate at a mass ratio of 1:1, and mix them to obtain a mixture.

[0119] S2. Planetary ball mill mechanical activation: All 500g of the mixture was put into a planetary ball mill, using 10mm diameter agate grinding balls at a ball-to-material ratio of 16:1. The mixture was continuously ground at 260r / min for 80min to obtain the alkaline residue-calcium sulfate composite activated product. Subsequently, steps S3 (microwave-chemical coupling activation) and S4 (ultrasonic dynamic aging) were skipped, and the obtained composite activated product was directly used for subsequent performance testing.

[0120] Test results showed that the carbon fixation rate was 35%, the 3-day compressive strength of the prepared filling material was 1.3 MPa, the 180-day compressive strength was 2.3 MPa, and moderate salt precipitation occurred after the 180-day curing period.

[0121] Compared to Comparative Example 1 (using dual-chamber staged ball milling), Comparative Example 2 (planetary ball milling) showed a slight improvement in carbon fixation rate and early strength, but the improvement in strength at 180 days was limited, and the degree of salt precipitation was more severe (moderate vs. slight), indicating that simple planetary ball milling did not show an advantage in long-term stability. More importantly, both Comparative Example 1 and Comparative Example 2 had significantly lower carbon fixation rates (32%, 35%), strengths (2.0 and 2.3 MPa at 180 days), and salt precipitation resistance than Example 3 (76% carbon fixation rate, 6.2 MPa at 180 days, and no salt precipitation), which adopted the complete "differentiated mechanical activation - microwave-chemical coupling activation - ultrasonic dynamic aging" process.

[0122] Comparative Example 5-3 (Single mechanical activation: Vibratory mill activation) This comparative example further explores the effects of another mechanical activation method, omitting subsequent key steps.

[0123] S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate to a moisture content of 0.8% respectively, and weigh 400g of alkali residue and 200g of calcium sulfate at a mass ratio of 2:1, and mix them to obtain a mixture.

[0124] S2. Mechanical activation using a vibratory mill: All 600g of the mixture was fed into a vibratory mill, with the amplitude set to 5mm and the vibration frequency to 32Hz. The mill was then ground for 60 minutes to obtain the alkaline residue-calcium sulfate composite activated product. Subsequently, steps S3 (microwave-chemical coupling activation) and S4 (ultrasonic dynamic aging) were skipped, and the obtained composite activated product was directly used for subsequent performance testing.

[0125] Test results showed that its carbon fixation rate was only 29%, the 3-day compressive strength of the prepared filling was 0.9 MPa, the 180-day compressive strength was 1.8 MPa, and obvious salt precipitation appeared after the 180-day curing period.

[0126] A comprehensive comparison of Comparative Example 1 (dual-cavity staged ball mill), Comparative Example 2 (planetary ball mill), and Comparative Example 3 (vibration mill) shows that, despite the differences in the mechanical activation equipment and parameters used, the products obtained through a single mechanical activation method all exhibited relatively low performance: carbon fixation rate was between 29% and 35%, 180-day compressive strength was between 1.8 and 2.3 MPa, and salting out was observed to varying degrees (from slight to obvious).

[0127] This indicates that for the specific system of alkali residue-sodium sulfate, relying solely on physical mechanical crushing and refining is insufficient to fully activate its reactivity, let alone suppress the long-term precipitation of easily soluble salt components, thus failing to meet the requirements of high-performance carbon-fixing filling materials. However, in Example 3, which used the same raw material ratio (1.5:1) as Comparative Example 1 and implemented the complete technical solution, the carbon fixation rate (76%) and 180-day strength (6.2 MPa) achieved a qualitative leap, and salt precipitation was completely eliminated. This significant difference conclusively proves that the multi-stage synergistic process of "differentiated mechanical activation—microwave-chemical coupling activation—ultrasonic dynamic aging" defined by the technical solution of this application is not a simple superposition of different activation methods, but rather produces a significant synergistic effect, solving technical problems that cannot be solved by a single method.

[0128] Comparative Example 6-1 (Single Chemical Activation - Calcium Chloride) This comparative example is used to verify the effect of omitting mechanical activation (step S2), microwave (microwave in step S3), and ultrasonic steps (ultrasonic steps in step S4) when only chemical excitation is used. The specific steps are as follows: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate (unground, original particle size ≤5mm) separately to a moisture content of 0.8%, and weigh 300g of alkali residue and 200g of calcium sulfate at a mass ratio of 1.5:1, mix them directly to obtain a mixture.

[0129] S3. Chemical activation: Spray 25g of a 15% calcium chloride aqueous solution (accounting for 5% of the total mass of the material) onto the mixture and stir at 120r / min for 5min until wet to obtain wet material.

[0130] S4. Aging: The wet material is sealed and aged for 5 days in a conventional environment of 20℃ and 85% relative humidity (without step S4 ultrasonic dynamic aging) to obtain the alkaline residue-calcium sodium sulfate composite activated product.

[0131] The performance test results of the obtained product are as follows: carbon fixation rate 41%, compressive strength of the prepared filler 1.5 MPa after 3 days, compressive strength 2.8 MPa after 180 days, and no obvious salting out after 180 days.

[0132] Compared with Example 3 (full process), although salting out was controlled, the carbon fixation rate, 3-day and 180-day intensity were significantly lower, indicating that the lack of fineness and reaction interface provided by mechanical activation made it difficult to significantly improve the activity of the system by chemical activation alone.

[0133] Comparative Example 6-2 (single chemical activation - aluminum sulfate, without mechanical activation and ultrasonic aging) This comparative example uses a different chemical activator. Steps S2 and S4 are also omitted. The specific steps are as follows: S1. Raw material pretreatment: Weigh 300g of dried alkali residue and 200g of calcium sulfate (unground) at a mass ratio of 1.5:1, mix them directly to obtain a mixture.

[0134] S3. Chemical activation: Spray 30g of 10% aluminum sulfate aqueous solution (accounting for 6% of the total mass of the material), stir at 150r / min for 4min until moistened, and obtain wet material.

[0135] S4. Aging: Subsequently, the product was aged for 5 days at 20℃ and 85% relative humidity to obtain the alkaline residue-calcium sulfate composite activated product. The performance test results of the obtained product were as follows: carbon fixation rate of 38%, compressive strength of the prepared filling material of 1.4 MPa after 3 days, compressive strength of 2.6 MPa after 180 days, and no obvious salt precipitation after 180 days.

[0136] Its performance is on the same order of magnitude as Comparative Example 4 and lower than that of Example 3, which once again confirms that simply changing the type of activator without combining mechanical activation and ultrasonic stabilization cannot achieve a breakthrough improvement in performance.

[0137] Comparative Example 6-3 (composite chemical activation, no mechanical activation and ultrasonic aging) This comparative example uses a composite activator to optimize the chemical activation effect, but steps S2 and S4 are still omitted. The specific steps are as follows: S1. Raw material pretreatment: Mix 300g of dried but unground alkali residue with 200g of calcium sulfate to obtain a mixture.

[0138] S3. Chemical activation: Spray 20g of calcium chloride-aluminum sulfate composite aqueous solution (mass ratio 2:1, total concentration 12%) (accounting for 4% of the total mass of the material), stir at 130 r / min for 6min until wet, and obtain wet material.

[0139] S4. Aging: Subsequently, the product was aged for 5 days at 20℃ and 85% relative humidity to obtain the alkaline residue-calcium sulfate composite activated product. The performance test results of the obtained product were as follows: carbon fixation rate 45%, compressive strength of the prepared filling material 1.7 MPa after 3 days, compressive strength 3.1 MPa after 180 days, and no salt precipitation after 180 days.

[0140] This comparative example represents the optimal effect of a single / composite chemical activation pathway. While its carbon fixation rate and strength are slightly better than those of Comparative Examples 4 and 5, they still lag significantly behind Example 3 (76% carbon fixation rate, 6.2 MPa strength after 180 days). This clearly demonstrates that even with optimized chemical activation, without mechanical activation to create a sufficient reaction interface, and without ultrasonic dynamic aging to promote microstructural ordering and stabilization, there are significant bottlenecks in improving the system's activity and final performance.

[0141] Comparative Example 7 (raw materials directly mixed) 300g of alkaline residue was directly mixed with 200g of sodium sulfate (dried to a moisture content of only 0.8%, without any activation treatment). Performance testing: carbon fixation rate 28%; 3-day strength of the filling material 0.8MPa, 180-day strength 1.5MPa; severe salting out and cracking occurred after 180 days.

[0142] Comparative Example 8 (Single Ultrasound Assistance) 300g of alkaline residue was mixed with 200g of calcium sulfate (unground, unactivated) and aged for 5 days at 20℃ and 85% relative humidity, with ultrasonic treatment initiated every 12 hours (same as Example 3). Performance testing: carbon fixation rate 30%; 3-day strength of the filling material 0.9MPa, 180-day strength 1.7MPa; moderate salting out occurred after 180 days.

[0143] In summary, the core value of this application's technical solution lies in its construction of a multi-stage synergistic dry composite activation and stabilization process involving "differentiated mechanical activation—microwave-chemical coupling activation—ultrasonic dynamic aging." This solution successfully solves the two core challenges of low reactivity and easy salting out in the alkali residue-calcium sulfate system through deep synergy and sequential optimization of each step.

[0144] Specifically, step S2 (differentiated mechanical activation) employs a targeted design of "prioritizing coarse grinding to crush calcium sulfate, followed by fine grinding," creating a high-quality material foundation with a high specific surface area, reasonable particle size distribution, and uniform mixing for subsequent processing. This is the physical prerequisite for achieving efficient activation. Step S3 (microwave-chemical coupling activation) utilizes the internal heating and non-thermal effects of microwaves to achieve deep, rapid, and uniform chemical interaction between the activator and material particles with extremely low liquid phase dosage. This is the key chemical driver for breaking through the upper limit of the system's reactivity. Step S4 (ultrasonic dynamic aging) further optimizes the microstructure during the aging period through intermittent ultrasonic treatment, promoting product nucleation, growth, and densification. This is the final stabilization step for achieving long-term structural stability (no salting out). The stepwise performance comparison of a series of comparative examples (such as Comparative Examples 1-1, 2-1, 3-1, 4-1, etc.) (from single activation to multiple composites) conclusively proves that no single or dual composite technical path (such as mechanical only, chemical only, mechanical-chemical, microwave-chemical, etc.) can achieve the comprehensive technical effect of the whole process scheme of this application (76% carbon fixation rate, 6.2 MPa strength at 180 days and no salting out).

[0145] In other words, there are profound sequential dependencies and functional synergies among the steps, and the absence or replacement of any step will lead to a significant performance degradation. Therefore, the technical solution of this application is not a simple superposition of existing technologies, but rather produces an unexpected synergistic effect, constituting a complete, efficient, and non-obvious technical solution.

[0146] Example 5 This embodiment provides a system for implementing the above-described method for preparing the alkaline residue-calcium sulfate composite activated product, comprising: a drying and metering module 1, a dual-cavity graded ball milling module 2, a microwave-chemical coupling activation module 3, an ultrasonic dynamic aging module 4, and a linkage control module 5, connected in sequence. Wherein: The drying and metering module 1 is used to dry the alkali residue and sodium sulfate to a moisture content of no more than 1.0%, and to meter and mix them at a mass ratio of 1.8:1 to 1:1.2.

[0147] The dual-cavity classifying ball mill module 2 includes a coarse grinding chamber and a fine grinding chamber. Its configuration is as follows: metered calcium sulfate is preferentially fed into the coarse grinding chamber, which contains grinding balls with a diameter of 12–16 mm and a ball-to-material ratio of 13:1–16:1, and crushed at a speed of 180–220 r / min for 30–40 min; then, the coarsely ground calcium sulfate and alkali residue are simultaneously fed into the fine grinding chamber, which contains grinding balls with a diameter of 6–10 mm and a ball-to-material ratio of 14:1–17:1, and jointly ground at a speed of 260–300 r / min for 45–55 min, ultimately obtaining a composite activated powder with a specific surface area of ​​450–620 m² / kg and a D90 not greater than 18 μm.

[0148] The microwave-chemical coupling activation module 3 includes a microwave generator, a stirring mechanism, a spray nozzle assembly, and a temperature detection assembly. Its working process is as follows: receiving the composite activated powder, preheating it at a microwave power of 150-250W for 6-9 minutes, and then spraying an activator solution (such as calcium chloride solution, aluminum sulfate solution, or their compound solution) with a concentration of 12%-19% through the spray nozzle assembly in a segmented spraying manner (the spraying rate is gradually increased from 0.5 mL / s to 1.2 mL / s). The amount of solution added is 3%-7% of the total mass of the powder. After the spraying is completed, it is irradiated again at a microwave power of 350-480W for 12-18 minutes, and the temperature of the material is controlled at 45-55℃ through linkage between the temperature detection assembly and the microwave generator to obtain a wet mixture.

[0149] The ultrasonic dynamic aging module 4 includes a sealed curing tank, an ultrasonic transducer array, an intelligent spray water replenishment unit, and a temperature and humidity sensor. Its working process is as follows: receiving wet mixed materials and aging them for 3 to 6 days at 20±3℃ and relative humidity not less than 85%; during the aging period, intermittent ultrasonic treatment generated by the ultrasonic transducer array is initiated every 10 to 14 hours, with a frequency of 25 to 45 kHz, a power of 60 to 90 W, and a single treatment time of 4 to 6 minutes; the intelligent spray water replenishment unit automatically maintains the set humidity according to the feedback from the temperature and humidity sensor, and finally obtains the alkaline residue-calcium sodium sulfate composite activated product.

[0150] The linkage control module 5 is electrically connected to the aforementioned drying metering module, dual-cavity graded ball milling module, microwave-chemical coupling activation module, and ultrasonic dynamic aging module, respectively. It is used to perform real-time regulation and data recording of drying temperature, feeding rate, grinding parameters, microwave power, liquid spraying volume, stirring speed, ultrasonic parameters, and aging temperature and humidity, thereby realizing the automation and collaborative control of the entire pretreatment process.

[0151] The detailed descriptions listed above are merely specific descriptions of feasible implementations of this disclosure and are not intended to limit the scope of protection of this disclosure. All equivalent implementations or modifications made without departing from the spirit of the art of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A method for preparing an alkaline residue-calcium sulfate composite activated product, characterized in that, Includes the following steps: S1. Raw material pretreatment: Dry the alkali residue and calcium sulfate separately until the moisture content is no more than 1.0%. The mass ratio of the alkali residue and the calcium sulfate is 1.8:1 to 1:1.

2. S2. Differentiated mechanical activation: The calcium sulfate obtained in step S1 is preferentially fed into the coarse grinding chamber of the dual-chamber classifying ball mill for preferential crushing. Then, the coarsely ground calcium sulfate and the alkaline residue obtained in step S1 are simultaneously fed into the fine grinding chamber of the dual-chamber classifying ball mill to jointly grind the mixture of the two to obtain composite activated powder. S3. Microwave-chemical coupling activation: The composite activated powder obtained in step S2 is placed in a microwave activation cavity for microwave preheating. Then, an activator solution is sprayed in under stirring conditions. After the spraying is completed, microwave irradiation is continued and the material temperature is controlled at 45-55℃ to obtain a wet mixture. S4. Ultrasonic dynamic aging: The wet mixture obtained in step S3 is transferred to a closed aging device and aged at 20±3℃ and relative humidity not less than 85%; during the aging period, intermittent ultrasonic treatment is performed, the frequency of which is 25~45kHz, and it is started once every 10~14h to obtain the alkaline residue-calcium sodium sulfate composite activated product.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the alkaline residue to calcium sulfate is 1.5:

1.

3. The preparation method according to claim 1, characterized in that, In step S2, the diameter of the grinding balls in the coarse grinding chamber is 12-16 mm, the ball-to-material ratio is 13:1-16:1, the rotation speed is 180-220 r / min, and the crushing time of calcium sulfate in the coarse grinding chamber is 30-40 min; the diameter of the grinding balls in the fine grinding chamber is 6-10 mm, the ball-to-material ratio is 14:1-17:1, the rotation speed is 260-300 r / min, and the combined grinding time is 45-55 min; the D90 of the obtained composite activated powder is not greater than 18 μm.

4. The preparation method according to claim 1, characterized in that, In step S3, the concentration of the activator solution is 12% to 19%.

5. The preparation method according to claim 4, characterized in that, The activator solution is at least one of calcium chloride solution and aluminum sulfate solution.

6. The preparation method according to claim 5, characterized in that, In step S3, the activator solution is added in stages by spraying, with the spraying rate gradually increasing from 0.5 mL / s to 1.2 mL / s.

7. The preparation method according to claim 1, characterized in that, In step S4, the aging time is 3 to 6 days; the ultrasonic treatment power is 60 to 90 W, and the single treatment time is 4 to 6 minutes.

8. A system for carrying out the preparation method according to any one of claims 1 to 7, characterized in that, It includes a drying and metering module, a dual-cavity graded ball milling module, a microwave-chemical coupling activation module, an ultrasonic dynamic aging module, and a linkage control module connected in sequence; The linkage control module is electrically connected to the drying and metering module, the dual-cavity graded ball milling module, the microwave-chemical coupling activation module, and the ultrasonic dynamic aging module, respectively.

9. The system according to claim 8, characterized in that, The microwave-chemical coupling activation module includes a microwave generator, a stirring mechanism, a spray nozzle assembly, and a temperature detection assembly.

10. The system according to claim 8, characterized in that, The ultrasonic dynamic aging module includes a sealed curing tank, an ultrasonic transducer array, an intelligent spray water replenishment unit, and a temperature and humidity sensor.

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