Preparation of powdery accelerator masterbatch from aluminum ash and aluminum slag and its production process

Abstract

The application belongs to the technical field of quick-setting agent preparation, and particularly relates to a production process for preparing a powdery quick-setting agent master batch from aluminum ash and aluminum slag; the production process for preparing the powdery quick-setting agent master batch from the aluminum ash and the aluminum slag comprises the following steps: hazardous waste pretreatment and aluminum particle separation and recovery, ingredient mixing and clinker preparation by calcination, clinker grinding and finished product packaging, and dust removal ash intelligent closed-loop recycling control; the composite activator added in the application can effectively adsorb and fix the chloride ions in the dust removal ash, smooth the fluctuations in the content of Al2O3 in the dust removal ash, induce the early and rapid generation of needle bar-shaped ettringite crystals in the cement paste, significantly shorten the initial setting and final setting times, improve the early mechanical strength, and effectively avoid the late strength reduction; the dust removal ash intelligent closed-loop recycling control step is combined with the composite activator, the recycling ratio is intelligently adjusted through online detection, the ingredient system component is accurately controlled, and the quality of the quick-setting agent master batch product is uniform and stable.

Description

Technical Field

[0001] This invention belongs to the field of accelerator preparation technology, specifically relating to a powdered accelerator masterbatch prepared from aluminum ash and aluminum slag and its production process. Background Technology

[0002] In recent years, the resource utilization of aluminum ash to prepare concrete quick-setting admixture masterbatch has become the mainstream direction for the high-value utilization of hazardous waste. This approach can not only achieve the compliant disposal of aluminum ash, but also prepare quick-setting admixtures that are in high demand in the building materials industry, thus balancing environmental and economic benefits.

[0003] Existing processes for preparing accelerators from aluminum ash mostly only involve basic pretreatment, mixing, calcination, and grinding, and generally suffer from several technical defects: First, dust generated in various stages of production is often directly discharged or recycled in a fixed proportion, easily leading to excessive chloride ion content and large fluctuations in active components in the accelerator masterbatch, directly affecting the stability of concrete setting time and later strength; Second, high-temperature and normal-temperature dust generated in different stages are not collected and centrally managed, resulting in poor recycling matching, low resource utilization, and the continued generation of secondary solid waste; Third, traditional processes lack intelligent recycling control mechanisms based on component detection, failing to balance aluminum ash resource utilization rate and product quality stability. Therefore, developing an aluminum ash-based accelerator masterbatch preparation process with online component detection and closed-loop recycling has become an urgent direction to be addressed in this field. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a process for preparing powdered accelerator masterbatch using aluminum ash and aluminum slag. This invention involves a closed-loop pretreatment process to separate aluminum particles from the aluminum ash and slag, followed by high-temperature calcination to prepare clinker, and then fine grinding and packaging of the clinker. This is combined with core processes such as graded collection of dust collector ash and intelligent closed-loop recycling control of the dust collector ash, forming a comprehensive collaborative production solution that achieves both hazardous component control and a stable supply of active components. This solves the technical problems in existing aluminum ash accelerator preparation processes, including the accumulation of impurities and chloride ions due to the extensive recycling of dust collector ash, large fluctuations in product performance, low resource utilization, and the difficulty in balancing hazardous waste disposal and product quality stability. The powdered accelerator masterbatch prepared using this process, when applied to cement, can effectively optimize the structure of hydration products, exhibiting excellent accelerator setting performance and mechanical strength. The product quality is uniform and stable, with no secondary pollution throughout the process, resulting in significant environmental and economic benefits.

[0005] To address the shortcomings of existing technologies, the present invention adopts the following technical solution: This invention provides a production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, specifically including the following preparation steps: S1, Hazardous waste pretreatment and aluminum particle separation and recycling: Aluminum ash slag raw materials that meet the hazardous waste transportation specifications are transported in a sealed manner to a fully enclosed, leak-proof negative pressure pretreatment workshop. The aluminum ash slag raw materials are fed into a fully enclosed noise-reducing ball mill for grinding and crushing. After grinding to a particle size ≤5mm, they are graded and screened to separate aluminum particles and secondary aluminum ash. The dust-containing gas generated by the ball mill and screening equipment is collected by a gas collection hood and sent to the first bag filter for treatment. After purification, the exhaust gas meets the emission standards, and the pretreated dust is collected and transported to the dust buffer tank for temporary storage. The metallic aluminum particles obtained by screening and separation are transported to a special aluminum particle temporary storage area for sealed storage. S2, Ingredient mixing and calcination to prepare clinker: The secondary aluminum ash obtained in step S1 is precisely mixed with gravel and sodium carbonate in a ratio of 6-7:2-2.5:1-1.5. At the same time, a composite activator is added. The mixture is fed into a mixer via a closed screw conveyor and stirred evenly to obtain a mixed raw material. The mixed raw material is continuously fed into a rotary kiln for high-temperature calcination. The calcination temperature is controlled at 1100-1300℃ and the calcination time is 60-90 minutes. The secondary aluminum ash is rendered harmless through high-temperature calcination, and accelerator masterbatch clinker is generated. The high-temperature exhaust gas generated in the rotary kiln calcination section is sequentially purified through an SNCR denitrification system, a gravity dust collector, a cyclone dust collector, and a second bag filter to remove nitrogen oxides and dust from the exhaust gas. The purified exhaust gas meets emission standards. At the same time, the dust collected in the high-temperature section is transported to a dust ash buffer tank for temporary storage via a sealed pipeline. S3, Clinker Grinding and Finished Product Packaging: The quick-setting agent masterbatch clinker obtained in step S2 is ground by a ball mill and stored in a finished product storage tank for packaging and sale. The dust-laden gas generated in the grinding and packaging sections is collected by a gas collection hood and sent to the third bag filter for treatment. After purification, the exhaust gas is discharged. At the same time, the collected ambient temperature section dust is transported through a sealed pipeline to the dust buffer tank and mixed with the high temperature section dust and pre-treated dust to obtain mixed dust. S4, Intelligent Closed-Loop Recycling Control of Dust Collector Ash: An online component detection device is installed in the dust collector ash buffer tank to continuously detect the mixed dust collector ash in the tank in real time. Based on the detection results, the system automatically adjusts the process of recycling the mixed dust collector ash into the preparation of mixed raw materials in S2.

[0006] Furthermore, the composite activator comprises raw materials in the following mass ratio: metakaolin: dilute hydrochloric acid solution: gypsum dihydrate (CaSO4·2H2O) = 3:9-15:1; The preparation method of the composite activator includes the following steps: (1) Pulverize the metakaolin and pass it through a 200-mesh sieve to obtain metakaolin powder. Take a dilute hydrochloric acid solution with a concentration of 1.0-1.5 mol / L, mix the metakaolin with the dilute hydrochloric acid solution, stir and activate it in a water bath at 60-80℃ for 90-120 min, filter it, wash it with deionized water until the pH of the filtrate is neutral, dry it at 105℃ to constant weight, and then calcine it at 400-500℃ for 60-90 min to obtain modified metakaolin. (2) The modified metakaolin is dried at a low temperature of 200-300℃ for 60-90 minutes. The dried modified metakaolin and gypsum dihydrate are then put into a high-speed mixer and dry-mixed for 10-15 minutes to obtain a uniform mixed powder. (3) Slowly spray 8-12% of the total mass of the mixed powder into the mixed powder, while stirring and wetting, so that the powder forms a uniform paste precursor. Dry the paste precursor at low temperature and then grind it into ultrafine powder with a particle size ≤45μm to obtain the composite activator.

[0007] Furthermore, the online component monitoring indicators include aluminum oxide (Al2O3) content, sodium oxide (Na2O) content, and chloride ion (Cl) content. - )content; The system control method for online component monitoring is as follows: When Cl is detected in the mixed dust... - When the content is <1.5wt% and the Al2O3 content meets the standard, the mixed dust is returned to step S2 through a sealed pipe at a first reuse ratio of 5-10%, and then mixed with secondary aluminum ash, gravel, and sodium carbonate before entering the rotary kiln for calcination. When Cl is detected in the mixed dust... - When the content is ≥1.5wt%, the recycling ratio is automatically reduced to the second recycling ratio of 1-5% and returned to step S2, or recycling is suspended and the dust is temporarily stored in a buffer tank. After being diluted with low-chlorine secondary aluminum ash until the chloride ion content meets the standard, it can be recycled. When the Al2O3 content in the mixed dust is detected to be lower than the preset threshold, the recycling ratio of the dust is automatically increased to replenish the effective aluminum content in the batching system and ensure the stable activity of the accelerator masterbatch.

[0008] The present invention also provides a powdered quick-setting agent masterbatch prepared from aluminum ash and aluminum slag, wherein the powdered quick-setting agent masterbatch prepared from aluminum ash and aluminum slag is prepared by any of the production processes described herein.

[0009] All dust from each work section is recycled in a closed loop with no external discharge. Small amounts of hazardous waste, such as waste packaging bags and waste engine oil, generated during the production process are collected and temporarily stored in a dedicated hazardous waste storage room. These wastes are then regularly handed over to a qualified hazardous waste disposal unit for unified treatment. The project generates no production wastewater. Initial rainwater is treated in a sedimentation tank, and domestic sewage is treated in an oil separator and septic tank before being discharged into the park's sewage network, achieving full-process environmental compliance.

[0010] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention employs a fully enclosed negative pressure operation and comprehensive dust control throughout the entire process, eliminating the risks of fugitive dust emissions, hazardous waste leakage, and secondary pollution at the source, achieving a balance between environmental benefits and production efficiency. The composite activator added to this invention is coupled with the intelligent closed-loop recycling control step for dust collector ash, resulting in enhanced efficiency. The modified metakaolin in the composite activator possesses abundant pore structure and ion exchange properties, efficiently adsorbing and fixing chloride ions that easily accumulate in the recycled dust collector ash, significantly reducing the harmful effects of chloride ions on concrete durability. This allows the system to safely increase the recycling ratio of dust collector ash while ensuring product performance. Simultaneously, the modified metakaolin can supplement the batching system with stable active aluminosilicate components, effectively smoothing fluctuations in Al2O3 content in the mixed dust collector ash and ensuring the stability of the accelerator masterbatch's activity. Furthermore, the composite activator can induce the rapid early formation of needle-like ettringite crystals in the cement paste, significantly shortening the initial and final setting times, improving early strength, and effectively preventing later strength reduction. This results in an accelerator masterbatch with both excellent accelering properties and long-term mechanical stability. The intelligent closed-loop recycling control steps for dust collector ash of this invention involve online synchronous detection of Cl in the mixed dust collector ash. - The process involves intelligently adjusting the reuse ratio based on Al2O3 content fluctuations, combined with the stabilizing effect of the composite activator, to achieve precise control of the ingredient system composition, resulting in uniform and stable quality of the accelerator masterbatch. The composite activator forms a low-temperature eutectic system with secondary aluminum ash and sodium carbonate, appropriately reducing the calcination activation energy and ensuring a more complete calcination reaction. Simultaneously, dust from different stages is collected and uniformly controlled for reuse, achieving closed-loop digestion of solid waste and significantly improving the overall utilization rate of aluminum ash resources, transforming the waste loss from traditional processes into resource recycling and efficiency enhancement. The accelerator masterbatch prepared by this process, through calcination for harmless treatment and intelligent reuse control, thoroughly decomposes harmful impurities in aluminum ash, ensuring environmental safety and no hidden dangers in the product. It also stably guarantees the balance of active components in the masterbatch, resulting in uniform and controllable product quality. It can be directly packaged and sold externally without the need for complex on-site secondary mixing, adapting to various construction scenarios and balancing environmental, resource, and economic benefits. Attached Figure Description

[0011] Figure 1 This is a production process flow diagram of the present invention for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag. Figure 2This is a SEM image of the cement prepared according to the present invention after 1 h of hydration. Detailed Implementation

[0012] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0014] Unless otherwise specified, all methods described in the following embodiments are conventional. Unless otherwise specified, all materials used in the following embodiments are new materials purchased from the market.

[0015] The production process flow diagram for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag according to the present invention is as follows: Figure 1 The following examples were implemented: Example 1: This example provides a production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, specifically including the following preparation steps: S1, Hazardous Waste Pretreatment and Aluminum Particle Separation and Recycling: Aluminum ash slag raw materials that meet the hazardous waste transportation specifications are transported in a sealed manner to a fully enclosed, leak-proof negative pressure pretreatment workshop to avoid the unorganized diffusion of dust and leakage of raw materials. The aluminum ash slag is fed into a fully enclosed noise-reducing ball mill for grinding and crushing. After grinding to a particle size of 5mm, it is fed into a matching vibrating screen for grading and screening to separate aluminum particles and secondary aluminum ash. The dust-containing gas generated by the ball mill and screening equipment is collected by a gas collection hood and sent to the first bag filter for treatment. After purification, the exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The pretreated dust is collected and transported to a dust ash buffer tank for sealed temporary storage through a sealed insulated pipeline. The metallic aluminum particles obtained by screening and separation are transferred to a dedicated aluminum particle temporary storage area for sealed storage. S2, Ingredient mixing and calcination to prepare clinker: The secondary aluminum ash obtained in step S1 is mixed with gravel and sodium carbonate in a ratio of 6:2:1, and a composite activator is added. The amount of composite activator added is 3% of the total mass of secondary aluminum ash, gravel and sodium carbonate. The mixture is fed into a mixer through a closed screw conveyor and mixed evenly to obtain mixed raw materials. The mixed raw materials are continuously fed into a rotary kiln for high-temperature calcination. The calcination temperature is controlled at 1100℃ and the calcination time is 90min. The secondary aluminum ash is rendered harmless through high-temperature calcination, and at the same time, quick-setting agent masterbatch clinker is generated. The high-temperature exhaust gas generated in the rotary kiln calcination section is purified in multiple stages through an SNCR denitrification system, a gravity dust collector, a cyclone dust collector and a second bag filter to remove nitrogen oxides and dust from the exhaust gas. The purified exhaust gas is discharged through a 45m high exhaust stack to meet the standards. The high-temperature dust collected by the second bag filter is transported to a dust ash buffer tank for temporary storage through a closed insulated pipeline. S3, Clinker Grinding and Finished Product Packaging: The quick-setting agent masterbatch clinker obtained in step S2 is ground by a ball mill, stored in a finished product storage tank, and packaged for sale. The ambient temperature dust-laden gas generated in the grinding and packaging section is collected by a gas collection hood and sent to the third bag filter for treatment. After purification, the exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The ambient temperature dust collected by the third bag filter is synchronously transported to the dust buffer tank through a sealed pipeline and mixed with the high temperature dust and pre-treated dust to obtain mixed dust. S4, Intelligent closed-loop recycling control of dust collector ash: An online component detection device is installed in the dust collector ash buffer tank to continuously detect the mixed dust collector ash in the tank in real time, and upload the detection data to the intelligent control system in real time. Based on the detection results, the mixed dust collector ash is automatically adjusted to be recycled into the preparation process of the mixed raw materials in step S2.

[0016] The composite activator comprises the following raw materials in the following mass ratio: metakaolin: dilute hydrochloric acid solution: gypsum dihydrate = 3:9:1; The preparation method of the composite activator includes the following steps: (1) Pulverize the metakaolin and pass it through a 200-mesh sieve to obtain metakaolin powder with a particle size of 75 μm. Take a 1.0 mol / L dilute hydrochloric acid solution, mix the metakaolin with the dilute hydrochloric acid solution, stir and activate it for 120 min under a 60℃ water bath, filter it and wash it with deionized water until the pH of the filtrate is neutral, dry it at 105℃ to constant weight, and then calcine it at 400℃ for 90 min to obtain modified metakaolin. (2) The modified metakaolin was dried at 200℃ for 90 min to remove adsorbed water and further enhance surface activity. The dried modified metakaolin and gypsum dihydrate were put into a high-speed mixer and dry-mixed for 10 min to obtain a uniform mixed powder. (3) Slowly spray 8% of the total mass of the mixed powder into the mixed powder, while stirring and wetting, so that the powder forms a uniform paste precursor. Place the precursor at 60℃ to dry at a low temperature until the moisture content is 0.8%, and then grind it into ultrafine powder to a particle size of 45μm to obtain the composite activator.

[0017] The online component monitoring indicators include Al2O3 content, Na2O content, and Cl content. - content; The intelligent control system has a preset control algorithm, and the specific control method is as follows: When Cl is detected in the mixed dust... - When the content is 1.0 wt% and the Al2O3 content is 35 wt% and meets the standard, the mixed dust is returned to step S2 through a sealed pipe at a first reuse ratio of 5%, and mixed with secondary aluminum ash, gravel, and sodium carbonate before entering the rotary kiln for calcination. When Cl is detected in the mixed dust... - When the content is 1.5wt%, the recycling ratio is automatically reduced to 1% and the second recycling ratio is returned to step S2. The dust exceeding the standard is temporarily stored in a buffer tank. After being diluted with low-chlorine secondary aluminum ash until the chloride ion content meets the standard, it will be recycled. When the Al2O3 content in the mixed dust is detected to be 35wt%, the recycling ratio of the mixed dust is automatically increased to 8% to supplement the effective aluminum content in the batching system and ensure the stable activity of the accelerator masterbatch.

[0018] This embodiment also provides a method for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, wherein the powdered quick-setting agent masterbatch prepared using aluminum ash and aluminum slag is obtained by any of the production processes described herein.

[0019] Example 2: This example provides a production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, specifically including the following preparation steps: S1, Hazardous Waste Pretreatment and Aluminum Particle Separation and Recycling: Aluminum ash slag raw materials that meet the hazardous waste transportation specifications are transported in a sealed manner to a fully enclosed, leak-proof negative pressure pretreatment workshop to avoid the unorganized diffusion of dust and leakage of raw materials. The aluminum ash slag is fed into a fully enclosed noise-reducing ball mill for grinding and crushing. After grinding to a particle size of 3mm, it is fed into a matching vibrating screen for grading and screening to separate aluminum particles and secondary aluminum ash. The dust-containing gas generated by the ball mill and screening equipment is collected by a gas collection hood and sent to the first bag filter for treatment. After purification, the exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The pretreated dust is collected and transported to a dust ash buffer tank for sealed temporary storage through a sealed insulated pipeline. The metallic aluminum particles obtained by screening and separation are transferred to a dedicated aluminum particle temporary storage area for sealed storage. S2, Ingredient mixing and calcination to prepare clinker: The secondary aluminum ash obtained in step S1 is mixed with gravel and sodium carbonate in a ratio of 6.5:2:1.5, and a composite activator is added. The amount of composite activator added is 4% of the mass of secondary aluminum ash, gravel and sodium carbonate. The mixture is fed into a mixer through a closed screw conveyor and mixed evenly to obtain mixed raw materials. The mixed raw materials are continuously fed into a rotary kiln for high-temperature calcination. The calcination temperature is controlled at 1200℃ and the calcination time is 80min. The secondary aluminum ash is rendered harmless through high-temperature calcination, and quick-setting agent masterbatch clinker is generated at the same time. The high-temperature exhaust gas generated in the rotary kiln calcination section is purified in multiple stages through an SNCR denitrification system, a gravity dust collector, a cyclone dust collector and a second bag filter to remove nitrogen oxides and dust from the exhaust gas. The purified exhaust gas is discharged in compliance with standards through a 45m high exhaust stack. The high-temperature dust collected by the second bag filter is transported to a special dust buffer tank for temporary storage through a closed insulated pipeline. S3, Clinker Grinding and Finished Product Packaging: The quick-setting agent masterbatch clinker obtained in step S2 is ground by a ball mill, stored in a finished product storage tank, and packaged for sale. The ambient temperature dust-laden gas generated in the grinding and packaging section is collected by a gas collection hood and sent to the third bag filter for treatment. After purification, the exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The ambient temperature dust collected by the third bag filter is synchronously transported to the dust buffer tank through a sealed pipeline and mixed with the high temperature dust and pre-treated dust to obtain mixed dust. S4, Intelligent closed-loop recycling control of dust collector ash: An online component detection device is installed in the dust collector ash buffer tank to continuously detect the mixed dust collector ash in real time, and upload the detection data to the intelligent control system in real time. Based on the detection results, the mixed dust collector ash is automatically adjusted to be recycled into the preparation process of the mixed raw materials in step S2.

[0020] The composite activator comprises the following raw materials in the following mass ratio: metakaolin: dilute hydrochloric acid solution: gypsum dihydrate = 3:10:1; The preparation method of the composite activator includes the following steps: (1) Pulverize the metakaolin and pass it through a 200-mesh sieve to obtain metakaolin powder with a particle size of 65 μm. Take a 1.2 mol / L dilute hydrochloric acid solution, mix the metakaolin with the dilute hydrochloric acid solution, stir and activate it for 100 min under a 70℃ water bath, filter it and wash it with deionized water until the pH of the filtrate is neutral, dry it at 105℃ to constant weight, and then calcine it at 450℃ for 80 min to obtain modified metakaolin. (2) The modified metakaolin was dried at 240℃ for 75 minutes to remove adsorbed water and further enhance surface activity. The dried modified metakaolin and gypsum dihydrate were put into a high-speed mixer and dry-mixed for 12 minutes to obtain a uniform mixed powder. (3) Slowly spray 10% of the total mass of the mixed powder into the mixed powder, while stirring and wetting, so that the powder forms a uniform paste precursor. Place the precursor at 70℃ to dry at a low temperature until the moisture content is 0.5%, and then grind it into ultrafine powder to a particle size of 35μm to obtain the composite activator.

[0021] The online component monitoring indicators include Al2O3 content, Na2O content, and Cl content. - content; The intelligent control system has a preset control algorithm, and the specific control method is as follows: When Cl is detected in the mixed dust... - When the content is 0.85wt% and the Al2O3 content is 58.2wt% which meets the standard, the mixed dust is returned to step S2 through a sealed pipe at a first reuse ratio of 8%, and then mixed with secondary aluminum ash, gravel, and sodium carbonate before entering the rotary kiln for calcination. When Cl is detected in the mixed dust... - When the content is 1.65wt%, the recycling ratio is automatically reduced to 3% and the second recycling ratio is returned to step S2. The dust exceeding the standard is temporarily stored in a buffer tank. After being diluted with low-chlorine secondary aluminum ash until the chloride ion content meets the standard, it will be recycled. When the Al2O3 content in the mixed dust is detected to be 30wt%, the recycling ratio of the dust is automatically increased to 10% to supplement the effective aluminum content in the batching system and ensure the stable activity of the accelerator masterbatch.

[0022] This embodiment also provides a method for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, wherein the powdered quick-setting agent masterbatch prepared using aluminum ash and aluminum slag is obtained by any of the production processes described herein.

[0023] Example 3: This example provides a production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, specifically including the following preparation steps: S1, Hazardous Waste Pretreatment and Aluminum Particle Separation and Recycling: Aluminum ash slag raw materials that meet the hazardous waste transportation specifications are transported in a sealed manner to a fully enclosed, leak-proof negative pressure pretreatment workshop to avoid the unorganized diffusion of dust and leakage of raw materials. The aluminum ash slag is fed into a fully enclosed noise-reducing ball mill for grinding and crushing. After grinding to a particle size of 2mm, it is fed into a matching vibrating screen for grading and screening to separate aluminum particles and secondary aluminum ash. The dust-containing gas generated by the ball mill and screening equipment is collected by a gas collection hood and sent to the first bag filter for treatment. After purification, the exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The pretreated dust is collected and transported to a dust ash buffer tank for sealed temporary storage through a sealed insulated pipeline. The metal aluminum particles obtained by screening and separation are transferred to a special aluminum particle temporary storage area for sealed storage. The separated secondary aluminum ash is also processed. S2, Ingredient Mixing and Calcination for Clinker Preparation: The secondary alumina ash obtained in step S1 is mixed with gravel and sodium carbonate in a ratio of 7:2.5:1.5, and a composite activator is added. The amount of composite activator added is 5% of the mass of the secondary alumina ash, gravel, and sodium carbonate. The mixture is fed into a mixer via a closed screw conveyor and stirred evenly to obtain a mixed raw material. The mixed raw material is then continuously fed into a rotary kiln for high-temperature calcination. The calcination temperature is controlled at 1300℃, and the calcination time is 90 minutes. Calcination achieves secondary harmless treatment of aluminum ash and generates accelerator masterbatch clinker. The high-temperature exhaust gas generated in the rotary kiln calcination section is purified in multiple stages through an SNCR denitrification system, a gravity dust collector, a cyclone dust collector, and a second bag filter to remove nitrogen oxides and dust from the exhaust gas. The purified exhaust gas is discharged in compliance with standards through a 45m high exhaust stack. The high-temperature dust collected by the second bag filter is transported to a special dust buffer tank for temporary storage through a sealed and insulated pipeline, awaiting subsequent reuse and regulation. S3, Clinker Grinding and Finished Product Packaging: The quick-setting agent masterbatch clinker obtained in step S2 is ground by a ball mill and stored in a finished product storage tank for packaging and sale. The ambient temperature dust-laden gas generated in the grinding and packaging section is collected by a gas collection hood and sent to the third bag filter for treatment. The purified exhaust gas is discharged through a 20m high exhaust stack to meet the standards. The ambient temperature dust collected by the third bag filter is synchronously transported to the dust buffer tank through a sealed pipeline and mixed with the high temperature dust and pre-treated dust to obtain mixed dust. S4, Intelligent closed-loop recycling control of dust collector ash: An online component detection device is installed in the dust collector ash buffer tank to continuously detect the mixed dust collector ash in the tank in real time, and upload the detection data to the intelligent control system in real time. Based on the detection results, the mixed dust collector ash is automatically adjusted to be recycled into the preparation process of the mixed raw materials in step S2.

[0024] The composite activator comprises the following raw materials in the following mass ratio: metakaolin: dilute hydrochloric acid solution: gypsum dihydrate = 3:15:1; The preparation method of the composite activator includes the following steps: (1) Pulverize the metakaolin and pass it through a 200-mesh sieve to obtain metakaolin powder with a particle size of 75 μm. Take a 1.5 mol / L dilute hydrochloric acid solution, mix the metakaolin with the dilute hydrochloric acid solution, stir and activate it for 120 min under 80℃ water bath conditions, filter it and wash it with deionized water until the pH of the filtrate is neutral, dry it at 105℃ to constant weight, and then calcine it at 500℃ for 90 min to obtain modified metakaolin. (2) The modified metakaolin was dried at 300℃ for 90 min to remove adsorbed water and further enhance surface activity. The dried modified metakaolin and gypsum dihydrate were put into a high-speed mixer and dry-mixed for 15 min to obtain a uniform mixed powder. (3) Slowly spray 12% of the total mass of the mixed powder into the mixed powder, while stirring and wetting, so that the powder forms a uniform paste precursor. Place the precursor at 80℃ to dry at a low temperature until the moisture content is 0.6%, and then grind it into ultrafine powder to a particle size of 40μm to obtain the composite activator.

[0025] The online component monitoring indicators include Al2O3 content, Na2O content, and Cl content. - content; The intelligent control system has a preset control algorithm, and the specific control method is as follows: When Cl is detected in the mixed dust... - When the content is 0.5wt% and the Al2O3 content is 60.1wt% which meets the standard, the mixed dust is returned to step S2 through a sealed pipe at a first reuse ratio of 10%, and mixed with secondary aluminum ash, gravel, and sodium carbonate before entering the rotary kiln for calcination. When Cl is detected in the mixed dust... - When the content is 32wt%, the recycling ratio is automatically reduced to 5% and the process returns to step S2. The excessive dust is temporarily stored in a buffer tank and then recycled after being diluted with low-chlorine secondary aluminum ash until the chloride ion content meets the standard. When the Al2O3 content in the mixed dust is detected to be 30.5wt%, the recycling ratio of the dust is automatically increased to 12% to supplement the effective aluminum content in the batching system and ensure the stable activity of the accelerator masterbatch.

[0026] This embodiment also provides a method for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, wherein the powdered quick-setting agent masterbatch prepared using aluminum ash and aluminum slag is obtained by any of the production processes described herein.

[0027] The difference between Comparative Example 1 and Example 2 is that step S4 is omitted; the rest is exactly the same as Example 2.

[0028] The difference between Comparative Example 2 and Example 2 is that the addition of the composite activator is omitted, while the rest is exactly the same as Example 2.

[0029] The difference between Comparative Example 3 and Example 2 is that in step S4, only Cl is applied. - The test was conducted, and the rest of the test was exactly the same as in Example 2.

[0030] Experimental Examples: Using the powdered quick-setting agent masterbatches prepared from aluminum ash and aluminum slag in Examples 1-3 and Comparative Examples 1-3 of this invention as test samples, the following experimental examples were conducted: 1. Setting Time: The setting time of cement paste shall be in accordance with the "Accelerating Agent for Shotcrete" (GB / T 35159-2017). First, pour the required water (140g minus the water in the accelerator) and 400g of cement into the mixing pot in sequence. Adjust the mixer to low speed and mix for 30 seconds, then pause. Quickly add the liquid accelerator into the pot all at once, then continue mixing at low speed for 5 seconds, and then adjust to high speed for 15 seconds before stopping. After stopping, quickly place it in a circular mold, then gently tamp and vibrate it a few times to smooth the surface of the paste. Place it in a Vicat apparatus to test the setting time. Record the initial setting time and final setting time obtained from the test in Table 1.

[0031] 2. Compressive Strength: Pour the required water (450g minus the water in the accelerator) and 900g cement into the mixing bowl in sequence. First, adjust the mixer to low speed and mix the cement and water in the bowl at low speed for 30 seconds. Then, evenly add 1350g of standard sand during the second 30-second period. Then, adjust to high speed and mix for 30 seconds, followed by a pause. The pause time is 90 seconds. During the pause, scrape any insufficiently mixed mortar adhering to the inner wall, bottom, and mixing blades of the mixing bowl back into the bowl. Then, continue mixing at high speed for 30 seconds, and then add the weighed liquid accelerator. The manual adjustment procedure is to first mix at low speed for 5 seconds, then at high speed for 15 seconds, and then stop. Then, quickly transfer the mortar to the mortar mold, and then vibrate it on a vibrating table for 30 seconds. Smooth the surface, mark it, and place it in a standard curing chamber with the mold on. After 24 hours, demold and determine the compressive strength at the specified age. Test the 1-day compressive strength and 28-day compressive strength, and record the results in Table 1.

[0032] 3. Chloride ion content: The determination method is the potentiometric titration method specified in GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures". Weigh 5g of sample and place it in a 250mL beaker. Add 100mL of water and 4mL of nitric acid, and heat to a gentle boil to completely dissolve the sample. After cooling, transfer to a 250mL volumetric flask, dilute with water to the mark, shake well, and filter dry. Accurately transfer 50.00mL of the above filtrate to a 250mL beaker, add 50mL of water, and perform potentiometric titration with a standardized silver nitrate standard solution (0.05mol / L) under magnetic stirring, using a silver electrode as the indicator electrode and a saturated calomel electrode as the reference electrode. Record the volume of silver nitrate standard solution consumed at the titration endpoint. Perform a blank test simultaneously.

[0033] Chloride ion content is calculated using the following formula: Among them, w C1V1 represents the mass fraction of chloride ions; C represents the concentration of silver nitrate standard solution (mol / L); V1 represents the volume of silver nitrate standard solution consumed in titrating the sample (mL); V0 represents the volume of silver nitrate standard solution consumed in titrating the blank (mL); and m represents the sample mass (g). The arithmetic mean of two parallel determinations is taken as the result, and the absolute difference between the two determinations should not exceed 0.05%. The test results are recorded in Table 1.

[0034] Table 1: Cement performance test table for powdered quick-setting agent masterbatch prepared by the present invention using aluminum ash and aluminum slag

[0035] As shown in Table 1, the accelerator masterbatches prepared in Examples 1-3 of this invention have shorter initial and final setting times, excellent 1-day and 28-day compressive strengths, and low chloride ion content, resulting in the best overall performance. In Comparative Example 1, the elimination of the intelligent closed-loop recycling control step led to the accumulation of impurities and chloride ions in the system, resulting in a significantly prolonged setting time and a marked decrease in compressive strength. In Comparative Example 2, the omission of the composite activator caused a significant enrichment of chloride ions, resulting in poor performance. Comparative Example 3 only detected chloride ions without synergistic regulation of alumina content; although the chloride ion control effect was close to that of the examples, the effective aluminum component could not be accurately replenished, causing the early and later strengths to be significantly lower than those of this invention.

[0036] like Figure 2 As shown, Figure 2 (a) is a SEM image of blank cement after 1 h of hydration. Figure 2 (b) is a SEM image of cement paste containing the powdered quick-setting agent masterbatch prepared by aluminum ash and aluminum slag in Example 2 of the present invention after 1 h of hydration. As can be seen from the figure, in the blank cement paste, only some whiskers of hydration products are deposited on the surface of the cement paste. However, in the cement paste containing the powdered quick-setting agent masterbatch prepared by Example 2 of the present invention, needle-shaped ettringite can be clearly seen to be generated. This indicates that the incorporation of the powdered quick-setting agent masterbatch prepared by aluminum ash and aluminum slag in the present invention accelerates the hydration of C3A, promotes the generation of ettringite crystals, and thus shortens the setting time.

[0037] In summary, this invention organically combines closed pretreatment of aluminum ash slag, graded batching and calcination, fine grinding of finished product, and intelligent closed-loop recycling of dust collector ash to form a synergistic and efficient production process for powdered accelerator masterbatch. This not only achieves the harmless disposal and high-value utilization of hazardous waste but also avoids the accumulation of impurities and environmental pollution at the source. The composite activator added in this invention is coupled and enhanced with the intelligent closed-loop recycling control step of dust collector ash, enabling the system to safely increase the recycling ratio of dust collector ash while ensuring product performance. The accelerator masterbatch produced by this invention has excellent setting performance, mechanical strength, and product stability, effectively ensuring the complete development of cement hydration products and forming a dense and uniform hardened structure. Through the design of the intelligent closed-loop recycling control step of dust collector ash, this invention simultaneously achieves precise control of chloride ions and a stable supply of active aluminum components, possessing good prospects for industrial application and economic and environmental value.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag, characterized in that, Specifically, the preparation steps include the following: S1, Hazardous waste pretreatment and aluminum particle separation and recycling: The aluminum ash slag raw material is ground, crushed, and screened to obtain aluminum particles and secondary aluminum ash. The generated dusty waste gas is purified by the first bag filter and the pretreated dust is collected and transported to the dust buffer tank. S2, Ingredient mixing and calcination to prepare clinker: The secondary aluminum ash obtained in step S1 is mixed with gravel and sodium carbonate. At the same time, a composite activator is added to it. After stirring evenly, a mixed raw material is obtained. The mixed raw material is sent to a rotary kiln for high-temperature calcination to obtain accelerator masterbatch clinker. The dust-containing exhaust gas generated in the calcination section of the rotary kiln is collected, purified, and then discharged. The high-temperature section dust is also collected and transported to the dust buffer tank. S3, Clinker Grinding and Finished Product Packaging: The quick-setting agent masterbatch clinker obtained in step S2 is ground to obtain quick-setting agent masterbatch. The dust-containing exhaust gas generated in the grinding and packaging section is collected, treated by the third bag filter, and the ambient temperature section dust is collected and mixed with the dust obtained in steps S1 and S2 to obtain mixed dust. S4, Intelligent Closed-Loop Recycling Control of Dust Collector Ash: Online component detection is performed on the mixed dust collector ash in the dust collector ash buffer tank, and the mixed dust collector ash is automatically adjusted to be recycled into the preparation process of mixed raw materials in step S2 based on the detection results.

2. The production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag according to claim 1, characterized in that, The composite activator comprises the following raw materials in the following mass ratio: metakaolin: dilute hydrochloric acid solution: gypsum dihydrate = 3:9-15:1; The preparation method of the composite activator includes the following steps: (1) Take metakaolin, crush it, sieve it to obtain metakaolin powder, take dilute hydrochloric acid solution, mix the metakaolin powder with dilute hydrochloric acid solution, stir and activate it under water bath conditions, filter it, wash the filtrate until the pH is neutral, dry it, calcine and activate it to obtain modified metakaolin. (2) The modified metakaolin was dried at low temperature, and the dried modified metakaolin was mixed with gypsum dihydrate to obtain a mixed powder. (3) Spray deionized water into the mixed powder to obtain a paste precursor. Dry the paste precursor at low temperature and grind it to obtain a composite activator.

3. The production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag according to claim 2, characterized in that, In step (1), the concentration of the dilute hydrochloric acid solution is 1.0-1.5 mol / L; The calcination activation temperature is 400-500℃, and the time is 60-90 min.

4. The production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag according to claim 1, characterized in that, In step S2, the temperature of the high-temperature calcination is controlled at 1100-1300℃, and the calcination time is 60-90 min; In step S2, the purification process involves multi-stage purification through an SNCR denitrification system, a gravity dust collector, a cyclone dust collector, and a second bag filter, followed by exhaust gas emission after purification. The high-temperature dust collected by the second bag filter is transported to a dust buffer tank for temporary storage through a sealed, insulated pipe.

5. The production process for preparing powdered quick-setting agent masterbatch using aluminum ash and aluminum slag according to claim 1, characterized in that, In step S4, the indicators for online component detection include Al2O3 content, Na2O content, and Cl content. - content; The system control method for online component detection is as follows: When Cl is detected in the mixed dust... - When the content is <1.5wt% and the Al2O3 content is not less than 35wt%, the mixed dust is returned to step S2 through a sealed pipe at a first reuse ratio of 5-10%, and then mixed with secondary aluminum ash, gravel, and sodium carbonate before entering the rotary kiln for calcination. When Cl is detected in the mixed dust... - When the content is ≥1.5wt%, the recycling ratio is automatically reduced to a second recycling ratio of 1-5% and returned to step S2; When the Al2O3 content in the mixed dust is detected to be lower than the preset threshold of 35wt%, the recycling ratio of the mixed dust is automatically increased to 8-12% to supplement the effective aluminum content in the batching system.

6. A powdered quick-setting agent masterbatch prepared using aluminum ash and aluminum slag, characterized in that, It is prepared using the production process described in any one of claims 1-5.

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