Low-carbon cement grinding aid formula and preparation process

Abstract

This invention relates to the field of grinding aid technology, specifically to a low-carbon cement grinding aid formulation and preparation process. It is composed of bio-based modified xylan, modified composite solid waste filler, modified alkanolamine complex, chelating activating components, a low-carbon polyol system, and deionized water. The bio-based modified xylan is obtained by grafting and modifying xylan derived from agricultural waste. The modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud. The modified alkanolamine complex is an environmentally friendly system free of triethanolamine. The composition combines high-efficiency grinding aid with low-carbon and environmentally friendly characteristics. This invention breaks through the technical bottlenecks of traditional products, achieving excellent grinding enhancement performance and low-carbon and environmentally friendly characteristics through the synergistic effect of multiple components. It has a wide range of applicability, a simple production process, and good economic and social benefits.

Description

Technical Field

[0001] This invention relates to the field of grinding aid technology, specifically to a low-carbon cement grinding aid formulation and preparation process. Background Technology

[0002] Cement is an indispensable basic cementitious material in national economic construction. The cement grinding process accounts for more than 60% of the total electricity consumption in the cement production process. Cement grinding aids, as core admixtures that improve cement grinding efficiency, reduce production energy consumption, and optimize cement performance, are key additives for the cement industry to reduce costs, increase efficiency, and achieve low-carbon development. The market demand for grinding aid products that combine high efficiency, low carbon emissions, and environmental friendliness is becoming increasingly urgent.

[0003] Currently, the mainstream cement grinding aids used in the industry are mostly composed of petroleum-based alcohol amines such as triethanolamine and triisopropanolamine as core functional components, supplemented by conventional polyols and inorganic salts. While these products offer basic grinding aid effects, they suffer from several insurmountable technical defects in practical applications: First, they are highly dependent on petroleum-based raw materials, resulting in significant carbon emissions during raw material production and processing. Furthermore, the poor biodegradability of petroleum-based components fails to meet the requirements of low-carbon and environmentally friendly development. Second, their functions are limited, only achieving basic grinding aid effects. They lack sufficient ability to activate the hydration activity of slag, fly ash, and other admixtures in cement, failing to effectively reduce the high-carbon-emission content of cement clinker. Simultaneously, they do not adequately utilize bulk industrial solid wastes such as phosphogypsum and red mud, making it difficult to simultaneously meet the dual demands of grinding aid performance and solid waste resource utilization. Third, some products introduce high-chloride-ion and high-alkali-content components to enhance short-term effects, easily leading to problems such as steel reinforcement corrosion and alkali-aggregate reaction in cement concrete, severely impacting the long-term durability of engineering structures. Fourth, the synthesis processes of some existing modified grinding aids involve high-temperature, high-pressure reactions and the use of organic solvents, resulting in high energy consumption, large wastewater and waste gas emissions, and high environmental treatment costs, making it difficult to achieve synergistic improvement in performance and environmental protection. Therefore, developing cement grinding aids that combine high efficiency, low carbon emissions, environmental friendliness, high-value utilization of solid waste, and performance optimization has become a pressing technical challenge in this field. Summary of the Invention

[0004] (a) Technical problems to be solved The following technical problems exist with existing cement grinding aids: (1) Petroleum-based alcohol amine feedstocks have high carbon emissions and poor biodegradability; (2) Insufficient capacity for purification and high-value utilization of harmful ions in industrial solid wastes such as phosphogypsum and red mud; (3) The activity activation function is weak and the clinker dosage is difficult to reduce effectively; (4) The synthesis process is energy-intensive and has a heavy environmental protection burden. This invention provides a low-carbon cement grinding aid composition and its preparation process to solve the above-mentioned technical problems.

[0005] (II) Technical Solution A low-carbon cement grinding aid composition, by weight, comprises the following components: 8-22 parts of bio-based modified xylan, 15-35 parts of modified composite solid waste filler, 10-25 parts of modified alkanolamine complex, 3-12 parts of chelating activating component, 12-28 parts of low-carbon polyol system, and 10-25 parts of deionized water; wherein the bio-based modified xylan is obtained by carboxymethylation grafting modification of xylan derived from corn cob or sugarcane bagasse, with a degree of substitution of 0.6-1.2 and a number-average molecular weight of 8000-25000 Da; and the modified composite solid waste filler is composed of modified phosphogypsum and modified red mud at a mass ratio of 2-4. The mixture comprises: 1. Modified phosphogypsum, which is obtained by defluorination, dephosphorization and activation modification of industrial by-product phosphogypsum; modified red mud, which is obtained by acid dissolution activation and silane coupling agent nano-grafting modification of Bayer process red mud; the modified alkanolamine complex is composed of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 3-5:2-3:1; the chelating activating component is a mixture of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 1-2:3-5:2-3; the low-carbon polyol system is a mixture of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:2-3:1-2.

[0006] Preferably, the preparation process of the bio-based modified xylan is as follows: xylan with a purity of ≥95% is obtained by enzymatic hydrolysis of corn cob or sugarcane bagasse, and deionized water is added to prepare a suspension with a mass concentration of 15%-25%. The pH of the system is adjusted to 9-11, sodium hydroxide is added and alkalized at 35-55℃ for 30-60 min, then sodium chloroacetate is added and grafted at a constant temperature of 60-80℃ for 2-4 h. After the reaction is completed, the pH is adjusted to neutral, and the product is obtained after alcohol precipitation, washing, and drying. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:0.8-1.2:1.0-1.5.

[0007] Preferably, the modified phosphogypsum in the modified composite solid waste filler is prepared as follows: industrial by-product phosphogypsum is crushed and passed through a 200-mesh sieve, and a 5%-10% (w / w) calcium hydroxide aqueous solution is added at a liquid-to-solid ratio of 1.5-2:1. The mixture is stirred and reacted at 40-60°C for 60-90 minutes, filtered and washed until neutral, dried at 105-120°C, and then 1%-3% (w / w) of calcium stearate is added. The mixture is then stirred at 80-100°C. The modified red mud is prepared by surface modification for 30-45 minutes. The preparation process of the modified red mud is as follows: Bayer process red mud is crushed and passed through a 300-mesh sieve, 10%-15% by mass of dilute sulfuric acid is added, the liquid-solid ratio is 2-3:1, acid dissolution and activation is carried out at 50-70℃ for 90-120 minutes, filtered and washed until neutral, dried, and then 2%-5% by mass of silane coupling agent KH550 is added. Graft modification is carried out at 90-110℃ for 45-60 minutes.

[0008] Preferably, the modified amine complex is composed of 4-5 parts by weight of diethanol monoisopropanolamine, 2-3 parts by weight of triisopropanolamine, and 1 part by weight of glucosamine, and the free amine content in the complex is ≤0.5%, and the viscosity at 25°C is 150-300 mPa·s.

[0009] Preferably, the chelating activation component, by weight, consists of 1-2 parts of aminotrimethylenephosphonic acid, 3-4 parts of sodium citrate, and 2-3 parts of layered sodium silicate, and the chelating capacity of this component for phosphorus and fluoride ions is ≥150mg / g, and the 7-day activity activation coefficient for cementitious admixtures is ≥1.15.

[0010] Preferably, the composition is a liquid that, when left to stand for 90 days at 25°C in a sealed environment, shows no stratification, precipitation, or flocculation, has a solid content of 45%-55%, and a pH value of 9.5-10.5.

[0011] Preferably, the preparation process of the low-carbon cement grinding aid composition includes the following steps: Preparation of S1 bio-based modified xylan: Xylan is obtained by enzymatic hydrolysis and purification of corn cob or sugarcane bagasse with cellulase, followed by alkalization, carboxymethylation graft modification and post-treatment to obtain bio-based modified xylan with a degree of substitution of 0.6-1.2 for later use. Preparation of S2 modified composite solid waste filler: Modified phosphogypsum was prepared by defluorination, dephosphorization activation, and surface modification of industrial by-product phosphogypsum. Modified red mud was prepared by acid dissolution activation and coupling agent grafting modification of Bayer process red mud. The modified phosphogypsum and modified red mud were compounded in a certain proportion and ground until the specific surface area was ≥600 m². 2 / kg, to prepare modified composite solid waste filler for later use; Preparation of premixed S3 base mother liquor: Add the low-carbon polyol system and deionized water to the reactor according to the ratio, stir for 10-20 min at room temperature and pressure and a speed of 80-120 r / min, then add the modified alkanolamine complex and chelating activation component according to the ratio, heat to 35-50℃, and stir for 20-40 min to obtain a uniform base mother liquor; S4 final product composite homogenization: The bio-based modified xylan obtained from S1 and the modified composite solid waste filler obtained from S2 are added to the basic mother liquor of S3. Stir for 40-60 minutes at room temperature and pressure and a speed of 150-200 r / min. After stirring, let stand for 20-30 minutes to mature. Filter to remove insoluble impurities to obtain the low-carbon cement grinding aid composition.

[0012] Preferably, in step S1, the enzymatic hydrolysis and purification process of xylan is as follows: corn cobs or sugarcane bagasse are crushed to 40-60 mesh, deionized water is added to prepare a slurry with a solid content of 10%-15%, cellulase is added at 1.5%-3% of the dry basis raw material mass, the pH of the system is adjusted to 4.5-5.5, and enzymatic hydrolysis is carried out at 45-55℃ for 24-48 hours. After enzymatic hydrolysis, the enzyme is inactivated, filtered, decolorized, concentrated, precipitated with alcohol, and dried to obtain xylan with a purity ≥95%.

[0013] Preferably, in step S2, the mass ratio of modified phosphogypsum to modified red mud is 3:1. The mixture is ground using a vertical sand mill with zirconia beads as the grinding media. The grinding speed is 1200-1500 r / min and the grinding time is 30-60 min. The particle size D90 of the final modified composite solid waste filler is ≤10 μm.

[0014] Preferably, after the preparation of the basic mother liquor in step S3 is completed, the insoluble matter content of the system is detected and controlled to be ≤0.1% before proceeding to the next process; in step S4, the temperature of the system is controlled at 25-40℃ throughout the composite homogenization process, and after stirring, it is filtered under negative pressure through a 100-mesh filter. The fluctuation value of the batch-to-batch grinding system hourly output of the final product is ≤3%; the preparation process adopts normal pressure and reaction temperature not exceeding 120℃ throughout the process, the water recycling rate of the production process is ≥95%, no organic solvents are added in the production process, and no industrial solid waste is generated.

[0015] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: By using bio-based modified xylan as the core functional component, combined with a triethanolamine-free modified amine composite system, the product's biodegradability is significantly improved, and its carbon emissions throughout its entire life cycle are significantly reduced, aligning with the cement industry's green and low-carbon transformation development needs. This invention innovatively introduces modified composite solid waste filler, achieving high-value synergistic utilization of two types of bulk industrial solid waste. Through targeted activation and surface modification treatments, the adverse effects of harmful impurities in the solid waste are eliminated, while the filler is endowed with excellent grinding aid compatibility and hydration activity. This not only alleviates the environmental pressure caused by solid waste stockpiling but also reduces the product's resource consumption and environmental burden by replacing some chemical raw materials with modified industrial solid waste.

[0016] By synergistically combining chelating activating components with various functional components, the invention achieves a dual function of grinding enhancement and activity activation. This not only effectively optimizes the cement grinding process and improves grinding efficiency but also effectively activates the hydration activity of cementitious admixtures. While reducing the amount of cement clinker, it ensures and optimizes the mechanical and workability of the cement, making it suitable for cement production needs of various admixture systems. Furthermore, the product system of this invention introduces no harmful components, strictly controls chloride ion and alkali content, effectively avoiding durability risks during cement concrete application. The product also exhibits excellent storage stability and batch stability, is adaptable to different cement grinding processes, and has a wide range of applications. Attached Figure Description

[0017] Figure 1 This invention discloses a low-carbon cement grinding aid formulation preparation process; Figure 2 This is a grouped bar chart comparing the core application performance of the embodiments and comparative examples; Figure 3 This is a multi-sequence line graph comparing the green and low-carbon performance of the examples and comparative examples; Figure 4 This is a radar chart showing the combined performance of the embodiments and comparative examples with unified dimensions. Detailed Implementation

[0018] according to Figures 1 to 4 The specific embodiments of the present invention are as follows: This section provides a more detailed description of the present invention with reference to specific embodiments and comparative examples. The described embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, all experimental conditions and operating methods used in this invention are conventional experimental conditions and operating methods well-known to those skilled in the art. Unless otherwise specified, all raw materials, reagents, and equipment used are commercially available conventional products.

[0019] The low-carbon cement grinding aid composition of this invention is based on the synergistic compounding of bio-based modified xylan, modified composite solid waste filler, modified alkanolamine complex, chelating activation components, and a low-carbon polyol system. This constructs a triethanolamine-free, low-emission, and highly biodegradable grinding aid system, coupled with a low-temperature, atmospheric-pressure preparation process, achieving a synergistic improvement in grinding efficiency, activity activation, and low-carbon environmental protection. The detailed preparation method of the core functional components of this invention will be described first, followed by specific embodiments and comparative examples.

[0020] 1. Detailed preparation method of bio-based modified xylan The bio-based modified xylan used in this invention is prepared from agricultural waste such as corn cobs or sugarcane bagasse. High-purity xylan is first obtained through enzymatic hydrolysis and purification, and then modified by carboxymethylation grafting. The specific steps are as follows: (1) Enzymatic hydrolysis and purification of xylan: After washing and drying, corn cobs or sugarcane bagasse are crushed to 40-60 mesh using a universal pulverizer to obtain raw material powder; the raw material powder is added to deionized water to prepare a uniform slurry with a solid content of 10%-15%, which is then transferred to an enzymatic hydrolysis reactor. Cellulase (enzyme activity ≥10000U / g) is added at 1.5%-3% of the dry weight of the raw material. The pH of the system is adjusted to 4.5-5.5 with dilute acetic acid, the temperature is raised to 45-55℃, and the mixture is kept at a constant temperature and stirred for 24-48 hours. The stirring speed is controlled at 60-80 r / min. After hydrolysis, the system is heated to 90℃ and kept at that temperature for 10 minutes to inactivate the enzyme. The insoluble residue is removed by hot filtration to obtain crude enzymatic hydrolysate. Activated carbon (0.5%-1% by mass) is added to the crude enzymatic hydrolysate, and the mixture is heated to 60℃ and stirred for 30 minutes to decolorize. The activated carbon is removed by filtration, and the decolorized clear liquid is concentrated by reverse osmosis to a solid content ≥30%. Three times the volume of anhydrous ethanol is added to the concentrated liquid, and the mixture is allowed to stand for 12 hours to precipitate. The precipitate is collected by filtration, washed 2-3 times with anhydrous ethanol, and dried in a vacuum drying oven at 60℃ to constant weight to obtain xylan powder with a purity ≥95%.

[0021] (2) Carboxymethylation grafting modification: The xylan powder obtained above was added to deionized water to prepare a suspension with a mass concentration of 15%-25%, which was then transferred to a grafting reactor. The pH of the system was adjusted to 9-11 with a mass fraction of 20% sodium hydroxide aqueous solution. The prescribed amount of sodium hydroxide solid was added, and the system was alkalized by stirring at a constant temperature of 35-55℃ for 30-60 min, with the stirring speed controlled at 100-120 r / min. After alkalization, the prescribed amount of sodium chloroacetate was slowly added to the system, with the addition time controlled at 15-20 min. After the addition was completed, the temperature was raised to 60-80℃, and the grafting reaction was carried out by stirring at a constant temperature for 2-4 h. After the reaction was completed, the pH of the system was adjusted to neutral with dilute hydrochloric acid, and two volumes of anhydrous ethanol were added to the reaction solution. The mixture was allowed to stand for 8 h to precipitate, and the precipitate was collected by filtration. It was washed three times with a volume fraction of 80% ethanol aqueous solution, and then washed once with anhydrous ethanol. The mixture was dried in a vacuum drying oven at 65℃ to constant weight to obtain bio-based modified xylan. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate was 1:0.8-1.2:1.0-1.5. The modified xylan obtained had a degree of substitution of 0.6-1.2 and a number-average molecular weight of 8000-25000 Da. The degree of substitution was determined by acid-base titration, and the number-average molecular weight was determined by gel permeation chromatography.

[0022] 2. Detailed preparation method of modified composite solid waste filler The modified composite solid waste filler used in this invention is a mixture of modified phosphogypsum and modified red mud at a mass ratio of 2-4:1. The specific preparation steps are as follows: (1) Preparation of modified phosphogypsum: Industrial by-product phosphogypsum is coarsely crushed by a jaw crusher and then crushed by a ball mill through a 200-mesh sieve to obtain phosphogypsum powder; the phosphogypsum powder is added to a reaction vessel, and a 5%-10% (w / w) calcium hydroxide aqueous solution is added. The liquid-solid ratio is controlled at 1.5-2:1. The temperature is raised to 40-60℃, and the reaction is carried out at a constant temperature with stirring for 60-90 min. The stirring speed is controlled at 80-100 r / min to complete the defluorination and dephosphorization activation treatment. After the reaction is complete, the solid is collected by filtration, washed with deionized water until the washing liquid is neutral, and dried in a forced-air drying oven at 105-120℃ to constant weight to obtain activated phosphogypsum. The activated phosphogypsum is added to a high-speed mixer, heated to 80-100℃, and calcium stearate of 1%-3% of the dry weight of the activated phosphogypsum is added. The mixture is then mixed and modified at high speed at 1200-1500 r / min for 30-45 min. After cooling to room temperature, the modified phosphogypsum is obtained.

[0023] (2) Preparation of modified red mud: Bayer process red mud was taken, washed and dried, and then crushed through a 300-mesh sieve using a ball mill to obtain red mud powder; the red mud powder was added to a reaction vessel, and 10%-15% dilute sulfuric acid was added. The liquid-solid ratio was controlled at 2-3:1, the temperature was raised to 50-70℃, and the reaction was carried out at a constant temperature with stirring for 90-120 min. The stirring speed was controlled at 80-100 r / min to complete the acid dissolution and activation treatment; after the reaction was completed, the solid was collected by filtration and washed with deionized water until it was clean. The washing liquor is neutral. It is dried to constant weight in a 110℃ forced-air drying oven to obtain activated red mud. The activated red mud is added to a high-speed mixer and heated to 90-110℃. 2%-5% of the dry weight of the activated red mud is added as silane coupling agent KH550. The mixture is pre-diluted with 95% ethanol aqueous solution to a 20% solution. The mixture is then high-speed mixed and grafted at 1000-1200 r / min for 45-60 min. After cooling to room temperature, the modified red mud is discharged.

[0024] (3) Compound grinding: Weigh the modified phosphogypsum and modified red mud obtained above at a mass ratio of 2-4:1, add them to a vertical sand mill, use zirconia beads as the grinding medium, control the grinding speed at 1200-1500 r / min, and the grinding time at 30-60 min. After grinding, discharge the material to obtain a specific surface area ≥600 m². 2 Modified composite solid waste filler with a particle size D90≤10μm and a density of / kg.

[0025] 3. Explanation of other functional components The modified amine complex used in this invention is a compound of diethanol monoisopropanolamine, triisopropanolamine, and glucosamine in a mass ratio of 3-5:2-3:1. During compounding, the three raw materials are added to a stirred tank according to the ratio and stirred for 20 minutes at room temperature and pressure and a speed of 80 r / min until homogeneous. The resulting complex has a free amine content ≤0.5% and a viscosity of 150-300 mPa·s at 25°C. The chelating activation component used in this invention is aminotrimethylene. Phosphonic acid, sodium citrate, and layered sodium silicate are compounded in a mass ratio of 1-2:3-5:2-3. The three raw materials are mixed evenly according to the ratio during compounding. The resulting component has a chelating capacity for phosphorus and fluoride ions ≥150mg / g and a 7-day activity activation coefficient for cementitious materials ≥1.15. The low-carbon polyol system used in this invention is compounded in a mass ratio of ethylene glycol, diethylene glycol, and glycerol in a mass ratio of 1:2-3:1-2. The three raw materials are mixed evenly according to the ratio during compounding.

[0026] Example 1

[0027] This embodiment provides a low-carbon cement grinding aid composition, which, by weight, comprises: 15 parts of bio-based modified xylan, 25 parts of modified composite solid waste filler, 18 parts of modified alkanolamine complex, 8 parts of chelating activating component, 20 parts of low-carbon polyol system, and 14 parts of deionized water. The bio-based modified xylan is derived from corn cob, with a degree of substitution of 0.9 and a number-average molecular weight of 16000 Da. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:1.0:1.2. The modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud in a mass ratio of 3:1, with a specific surface area of ​​650 m². 2 / kg, particle size D90≤8μm; the modified alkanolamine complex is composed of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 4:2.5:1; the chelating activating component is composed of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 1.5:4:2.5; the low-carbon polyol system is composed of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:2.5:1.5.

[0028] The preparation process of the low-carbon cement grinding aid composition in this embodiment includes the following steps: Preparation of S1 bio-based modified xylan: Following the detailed preparation method of bio-based modified xylan described above, corn cobs were crushed to 50 mesh and prepared into a slurry with a solid content of 12%. 2% (dry weight) of cellulase was added, and the pH was adjusted to 5.0. The mixture was enzymatically hydrolyzed at 50°C for 36 hours. The enzyme was then inactivated, filtered, decolorized, concentrated, precipitated with alcohol, and dried to obtain xylan with a purity of 96.2%. The xylan was then prepared into a 20% (w / w) suspension, and the pH was adjusted to 10. Sodium hydroxide was added and alkalized at 45°C for 45 minutes. Sodium chloroacetate was slowly added, and the grafting reaction was carried out at 70°C for 3 hours. After the reaction, the pH was adjusted to neutral, and the mixture was precipitated with alcohol, washed, and dried to obtain the target bio-based modified xylan for later use. Preparation of S2 modified composite solid waste filler: Following the detailed preparation method of the aforementioned modified composite solid waste filler, industrial by-product phosphogypsum was crushed and passed through a 200-mesh sieve, and 8% (w / w) calcium hydroxide aqueous solution was added at a liquid-to-solid ratio of 1.8:1. The mixture was stirred and reacted at 50°C for 75 min, filtered and washed until neutral, dried at 110°C, and then 2% (w / w) calcium stearate was added. Surface modification was carried out at 90°C for 40 min to obtain modified phosphogypsum. Bayer process red mud was crushed and passed through a 300-mesh sieve, and then... 12% dilute sulfuric acid (liquid-to-solid ratio 2.5:1) was used for acid dissolution and activation at 60℃ for 105 min. After filtration and washing until neutral, and drying, 3.5% (dry basis) of silane coupling agent KH550 was added, and the mixture was grafted and modified at 100℃ for 50 min to obtain modified red mud. Modified phosphogypsum and modified red mud were weighed at a mass ratio of 3:1 and added to a vertical sand mill. The grinding speed was controlled at 1350 r / min and the grinding time was 45 min to obtain the target modified composite solid waste filler for later use. Preparation of premixed S3 base mother liquor: According to the formula ratio, add the low-carbon polyol system and deionized water to the atmospheric pressure reactor, and stir for 15 minutes at room temperature and pressure and a speed of 100 r / min to make the system uniformly mixed; then add the modified alkanolamine complex and chelating activation component according to the formula ratio, slowly raise the temperature to 40℃, and continue stirring at a speed of 100 r / min for 30 minutes to make all components completely dissolved and dispersed, and obtain a uniform and transparent base mother liquor. The mass content of insoluble matter in the system is detected to be 0.06%, which meets the requirement of ≤0.1%, and proceed to the next process; S4 final product homogenization: The bio-based modified xylan obtained in S1 and the modified composite solid waste filler obtained in S2 are slowly added to the base mother liquor obtained in S3. During the feeding process, the mixture is continuously stirred at room temperature and pressure at a speed of 180 r / min. After the feeding is completed, the system temperature is controlled at 30℃, and the stirring speed is maintained at 180 r / min for 50 min to fully disperse and composite the components. After stirring is completed, stirring is stopped, and the mixture is allowed to stand for 25 min to mature. Then, it is filtered through a 100-mesh filter under negative pressure to remove trace amounts of insoluble impurities, thus obtaining the low-carbon cement grinding aid composition of this embodiment.

[0029] The grinding aid composition prepared in this embodiment is a uniform and stable light brown liquid with a solid content of 50.2% and a pH value of 10.0. After standing for 90 days at 25°C in a closed environment, it showed no stratification, precipitation, or flocculation. The biodegradability rate is 72%, the chloride ion content is 0.012%, and the alkali content is 0.32%. The carbon emissions throughout its entire life cycle are reduced by 46% compared to traditional alkanolamine cement grinding aids. The total production time for a single batch is 5.5 hours, and the water recycling rate in the production process is 96%.

[0030] Example 2

[0031] This embodiment provides a low-carbon cement grinding aid composition, which, by weight, comprises: 8 parts of bio-based modified xylan, 15 parts of modified composite solid waste filler, 10 parts of modified alkanolamine complex, 3 parts of chelating activating component, 12 parts of low-carbon polyol system, and 25 parts of deionized water. The bio-based modified xylan is derived from sugarcane bagasse, with a degree of substitution of 0.6 and a number-average molecular weight of 8000 Da. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:0.8:1.0. The modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud in a mass ratio of 2:1, with a specific surface area of ​​610 m². 2 / kg, particle size D90≤10μm; the modified amine complex is composed of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 3:2:1; the chelating and activating components are composed of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 1:3:2; the low-carbon polyol system is composed of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:2:1.

[0032] The preparation process of the low-carbon cement grinding aid composition in this embodiment includes the following steps: Preparation of S1 bio-based modified xylan: Following the detailed preparation method of bio-based modified xylan described above, sugarcane bagasse was crushed to 40 mesh and prepared into a slurry with a solid content of 10%. Cellulase at a dry weight of 1.5% was added, the pH was adjusted to 4.5, and enzymatic hydrolysis was carried out at 45°C for 24 hours. After enzyme inactivation, filtration, decolorization, concentration, alcohol precipitation, and drying, xylan with a purity of 95.3% was obtained. The xylan was prepared into a suspension with a mass concentration of 15%, the pH was adjusted to 9, sodium hydroxide was added, and alkalization was carried out at 35°C for 30 minutes. Sodium chloroacetate was slowly added, and the grafting reaction was carried out at a constant temperature of 60°C for 2 hours. After the reaction was completed, the pH was adjusted to neutral, and the target bio-based modified xylan was obtained after alcohol precipitation, washing, and drying. Preparation of S2 modified composite solid waste filler: Following the detailed preparation method of the modified composite solid waste filler described above, industrial by-product phosphogypsum was crushed and passed through a 200-mesh sieve. A 5% (w / w) calcium hydroxide aqueous solution was added at a liquid-to-solid ratio of 1.5:1. The mixture was stirred and reacted at 40°C for 60 minutes. After filtration and washing until neutral, the mixture was dried at 105°C. Then, 1% (dry basis) calcium stearate was added, and the surface was modified at 80°C for 30 minutes to obtain modified phosphogypsum. Bayer process red mud was crushed and passed through a 300-mesh sieve. Add 10% dilute sulfuric acid (liquid to solid ratio 2:1), activate at 50℃ for 90 min, filter and wash until neutral, dry, add 2% silane coupling agent KH550 (dry basis), and graft modify at 90℃ for 45 min to obtain modified red mud; weigh modified phosphogypsum and modified red mud at a mass ratio of 2:1, add to a vertical sand mill, control the grinding speed at 1200 r / min, and grind for 30 min to obtain the target modified composite solid waste filler for later use; Preparation of premixed S3 base mother liquor: According to the formula ratio, add the low-carbon polyol system and deionized water to the atmospheric pressure reactor, and stir for 10 min at room temperature and pressure and a speed of 80 r / min to make the system uniformly mixed; then add the modified alkanolamine complex and chelating activation component according to the formula ratio, slowly raise the temperature to 35℃, and continue stirring at a speed of 80 r / min for 20 min to make all components completely dissolved and dispersed, and obtain a uniform and transparent base mother liquor. The mass content of insoluble matter in the system is 0.05%, which meets the requirement of ≤0.1%, and proceed to the next process; S4 final product homogenization: The bio-based modified xylan obtained in S1 and the modified composite solid waste filler obtained in S2 are slowly added to the basic mother liquor obtained in S3. During the feeding process, the mixture is continuously stirred at room temperature and pressure at a speed of 150 r / min. After the feeding is completed, the system temperature is controlled at 25℃, and the stirring speed is maintained at 150 r / min for 40 min to fully disperse and composite the components. After stirring is completed, stirring is stopped, and the mixture is allowed to stand for 20 min to mature. Then, it is filtered through a 100-mesh filter under negative pressure to remove trace amounts of insoluble impurities, thus obtaining the low-carbon cement grinding aid composition of this embodiment.

[0033] The grinding aid composition prepared in this embodiment is a uniform and stable light yellow liquid with a solid content of 45.1% and a pH value of 9.5. After standing for 90 days at 25°C in a closed environment, it showed no stratification, precipitation, or flocculation. The biodegradability rate is 68%, the chloride ion content is 0.015%, and the alkali content is 0.28%. The carbon emissions throughout its entire life cycle are reduced by 42% compared to traditional alkanolamine cement grinding aids. The total production time for a single batch is 4 hours, and the water recycling rate in the production process is 95.5%.

[0034] Example 3

[0035] This embodiment provides a low-carbon cement grinding aid composition, which, by weight, comprises: 22 parts of bio-based modified xylan, 35 parts of modified composite solid waste filler, 25 parts of modified alkanolamine complex, 12 parts of chelating activating component, 28 parts of low-carbon polyol system, and 10 parts of deionized water. The bio-based modified xylan is derived from corn cob, with a degree of substitution of 1.2 and a number-average molecular weight of 25,000 Da. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:1.2:1.5. The modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud in a mass ratio of 4:1, with a specific surface area of ​​680 m². 2 / kg, particle size D90≤7μm; the modified amine complex is composed of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 5:3:1; the chelating activating component is composed of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 2:5:3; the low carbon polyol system is composed of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:3:2.

[0036] The preparation process of the low-carbon cement grinding aid composition in this embodiment includes the following steps: Preparation of S1 bio-based modified xylan: Following the detailed preparation method of bio-based modified xylan described above, corn cobs were crushed to 60 mesh and prepared into a slurry with a solid content of 15%. Cellulase at a dry weight of 3% was added, and the pH was adjusted to 5.5. The mixture was enzymatically hydrolyzed at 55°C for 48 hours. After enzyme inactivation, filtration, decolorization, concentration, alcohol precipitation, and drying, xylan with a purity of 96.8% was obtained. The xylan was prepared into a suspension with a mass concentration of 25%, and the pH was adjusted to 11. Sodium hydroxide was added and alkalized at 55°C for 60 minutes. Sodium chloroacetate was slowly added, and the grafting reaction was carried out at a constant temperature of 80°C for 4 hours. After the reaction, the pH was adjusted to neutral, and the mixture was precipitated with alcohol, washed, and dried to obtain the target bio-based modified xylan for later use. Preparation of S2 modified composite solid waste filler: Following the detailed preparation method of the modified composite solid waste filler described above, industrial by-product phosphogypsum was crushed and passed through a 200-mesh sieve, and a 10% (w / w) calcium hydroxide aqueous solution was added at a liquid-to-solid ratio of 2:1. The mixture was stirred and reacted at 60°C for 90 min, filtered and washed until neutral, dried at 120°C, and then 3% (dry basis) calcium stearate was added. Surface modification was carried out at 100°C for 45 min to obtain modified phosphogypsum. Bayer process red mud was crushed and passed through a 300-mesh sieve, and then... Add 15% (w / w) dilute sulfuric acid at a liquid-to-solid ratio of 3:1, activate by acid dissolution at 70℃ for 120 min, filter and wash until neutral, dry, add 5% (dry basis) of silane coupling agent KH550, and graft modify at 110℃ for 60 min to obtain modified red mud; weigh modified phosphogypsum and modified red mud at a mass ratio of 4:1, add to a vertical sand mill, control the grinding speed at 1500 r / min, and grind for 60 min to obtain the target modified composite solid waste filler, for later use; Preparation of premixed S3 base mother liquor: According to the formula ratio, the low-carbon polyol system and deionized water are added to the atmospheric pressure reactor and stirred for 20 minutes at room temperature and pressure and a speed of 120 r / min to make the system uniformly mixed; then, according to the formula ratio, the modified alkanolamine complex and chelating activation component are added, the temperature is slowly raised to 50℃, and the stirring is continued for 40 minutes at a speed of 120 r / min to make all components completely dissolved and dispersed, so as to obtain a uniform and transparent base mother liquor. The mass content of insoluble matter in the system is tested to be 0.08%, which meets the requirement of ≤0.1%, and proceeds to the next process; S4 final product homogenization: The bio-based modified xylan obtained in S1 and the modified composite solid waste filler obtained in S2 are slowly added to the basic mother liquor obtained in S3. During the feeding process, the mixture is continuously stirred at room temperature and pressure at a speed of 200 r / min. After the feeding is completed, the system temperature is controlled at 40℃, and the stirring speed is maintained at 200 r / min for 60 min to fully disperse and composite the components. After stirring is completed, stirring is stopped, and the mixture is allowed to stand for 30 min to mature. Then, it is filtered through a 100-mesh filter under negative pressure to remove trace amounts of insoluble impurities, thus obtaining the low-carbon cement grinding aid composition of this embodiment.

[0037] The grinding aid composition prepared in this embodiment is a uniform and stable light brown liquid with a solid content of 54.8% and a pH value of 10.5. After standing for 90 days at 25°C in a closed environment, it showed no stratification, precipitation, or flocculation. The biodegradability rate is 66%, the chloride ion content is 0.010%, and the alkali content is 0.45%. The carbon emissions throughout its entire life cycle are 41% lower than those of traditional alkanolamine cement grinding aids. The total production time for a single batch is 6 hours, and the water recycling rate in the production process is 95%.

[0038] Example 4

[0039] This embodiment provides a low-carbon cement grinding aid composition, which, by weight, comprises: 12 parts of bio-based modified xylan, 20 parts of modified composite solid waste filler, 15 parts of modified alkanolamine complex, 6 parts of chelating activating component, 18 parts of low-carbon polyol system, and 19 parts of deionized water. The bio-based modified xylan is derived from sugarcane bagasse, with a degree of substitution of 0.8 and a number-average molecular weight of 12000 Da. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:0.9:1.1. The modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud in a mass ratio of 3.5:1, with a specific surface area of ​​630 m². 2 / kg, particle size D90≤9μm; the modified alkanolamine complex is composed of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 3.5:2.2:1; the chelating activating component is composed of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 1.2:3.5:2.2; the low-carbon polyol system is composed of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:2.2:1.2.

[0040] The preparation process of this embodiment is completely consistent with that of Example 1. The resulting grinding aid composition is a uniform and stable light yellow liquid with a solid content of 47.5% and a pH value of 9.8. After standing for 90 days at 25°C in a closed environment, there is no stratification, precipitation, or flocculation. The biodegradability rate is 70%, the chloride ion content is 0.013%, and the alkali content is 0.30%. The carbon emissions throughout the entire life cycle are reduced by 44% compared with traditional alkanolamine cement grinding aids. The total production time for a single batch is 5 hours, and the water recycling rate in the production process is 95.8%.

[0041] Comparative Example 1 This comparative example is a commercially available traditional alkanolamine-based cement grinding aid, which is currently the mainstream product in the industry. By weight, the formula consists of: 22 parts triethanolamine, 15 parts triisopropanolamine, 20 parts ethylene glycol, 8 parts anhydrous sodium sulfate, and 35 parts deionized water. It is prepared using a conventional room temperature compounding process, that is, all raw materials are added to a mixing tank and stirred at room temperature for 30 minutes to mix evenly.

[0042] Comparative Example 2 The only difference between this comparative example and Example 1 is that bio-based modified xylan is not added to the formulation, and the missing weight parts are made up with an equal amount of deionized water. The rest of the formulation composition and preparation process are completely consistent with Example 1.

[0043] Comparative Example 3 The only difference between this comparative example and Example 1 is that the modified composite solid waste filler is not added to the formula, and the missing weight parts are made up with an equal amount of deionized water. The rest of the formula composition and preparation process are completely consistent with Example 1.

[0044] Comparative Example 4 The only difference between this comparative example and Example 1 is that the modified amine complex is replaced with an equal mass of triethanolamine, while the rest of the formulation and preparation process are completely consistent with Example 1.

[0045] The grinding aids prepared in Examples 1-4 and Comparative Examples 1-4 were all incorporated into a closed-circuit grinding system of P·O 42.5 silicate cement at a dosage of 0.06% of the cement mass. Grinding tests and cement performance tests were conducted simultaneously, and the environmental performance and storage stability of the products were also tested. The results show that the grinding aid prepared in the embodiments of the present invention significantly improves grinding efficiency and produces more reasonable cement particle size distribution compared with the traditional products in the comparative example and products lacking core components. At the same time, it can effectively stimulate the hydration activity of cement admixtures. While reducing the clinker dosage, the mechanical properties, stability, and setting time of cement all meet the requirements of the national standard for general-purpose Portland cement. The product has excellent storage stability and batch stability, and can be adapted to various cement admixture systems with slag, fly ash, and steel slag alone or in combination, and is suitable for cement grinding processes of different scales. At the same time, the product does not introduce harmful components, has excellent biodegradability, and significantly reduces carbon emissions throughout its entire life cycle. The supporting preparation process has no organic solvent addition, no high-temperature and high-pressure reaction, low production energy consumption, low pollutant emissions, no generation of toxic and harmful by-products, and no industrial solid waste discharge, making it easy to achieve large-scale industrial production.

[0046] The following table compares the cement grinding performance and hardened cement paste mechanical properties of the examples and comparative examples: Table 1 The environmental performance, storage stability, and low-carbon indicators of the products in the examples and comparative examples are compared in the table below: Table 2 Based on the test results in the two comparison tables above, it can be seen that the low-carbon cement grinding aids prepared in each embodiment of the present invention are significantly superior to commercially available traditional alkanolamine grinding aids and comparative examples lacking core components in terms of application performance (such as improved cement grinding efficiency, enhanced mechanical properties, and reduced clinker content) and green performance (such as biodegradability, low carbon emissions, storage stability, and environmental protection). Specifically, the products in the embodiments, through the synergistic effect of bio-based components, modified solid waste fillers, compound alkanolamine systems, and chelated activating components, achieve both optimization of cement grinding efficiency and mortar strength, while significantly reducing carbon emissions throughout the product's life cycle and pollutant emissions during production, and also possess excellent long-term storage stability. In contrast, the traditional product in Comparative Example 1 suffers from weak performance, poor environmental friendliness, and insufficient stability. Comparative Examples 2-4, lacking a single core component, all exhibit varying degrees of performance degradation and a decline in environmental indicators. This fully demonstrates that the present invention, through specific formulation compounding and process optimization, achieves a synergistic breakthrough in grinding aid performance, low carbon emissions, environmental protection, and industrial adaptability, resulting in outstanding and stable technical effects.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-carbon cement grinding aid composition, characterized in that, The product, by weight, comprises the following components: 8-22 parts of bio-based modified xylan, 15-35 parts of modified composite solid waste filler, 10-25 parts of modified alkanolamine complex, 3-12 parts of chelating activating component, 12-28 parts of low-carbon polyol system, and 10-25 parts of deionized water; the bio-based modified xylan is obtained by carboxymethylation grafting modification of xylan derived from corn cob or sugarcane bagasse, with a degree of substitution of 0.6-1.2 and a number-average molecular weight of 8000-25000 Da; the modified composite solid waste filler is a mixture of modified phosphogypsum and modified red mud in a mass ratio of 2-4:

1. The modified phosphogypsum is obtained by defluorination, dephosphorization and activation modification of industrial by-product phosphogypsum; the modified red mud is obtained by acid dissolution activation and silane coupling agent nano-grafting modification of Bayer process red mud; the modified alkanolamine complex is a mixture of diethanol monoisopropanolamine, triisopropanolamine and glucosamine in a mass ratio of 3-5:2-3:1; the chelating activating component is a mixture of aminotrimethylenephosphonic acid, sodium citrate and layered sodium silicate in a mass ratio of 1-2:3-5:2-3; the low-carbon polyol system is a mixture of ethylene glycol, diethylene glycol and glycerol in a mass ratio of 1:2-3:1-2.

2. The low-carbon cement grinding aid composition according to claim 1, characterized in that, The preparation process of the bio-based modified xylan is as follows: xylan with a purity of ≥95% is obtained by enzymatic hydrolysis of corn cob or sugarcane bagasse, and deionized water is added to prepare a suspension with a mass concentration of 15%-25%. The pH of the system is adjusted to 9-11, sodium hydroxide is added and alkalized at 35-55℃ for 30-60 min, then sodium chloroacetate is added and grafted at 60-80℃ for 2-4 h. After the reaction is completed, the pH is adjusted to neutral, and the product is obtained after alcohol precipitation, washing, and drying. The mass ratio of xylan, sodium hydroxide, and sodium chloroacetate is 1:0.8-1.2:1.0-1.

5.

3. The low-carbon cement grinding aid composition according to claim 1, characterized in that, The modified composite solid waste filler, specifically the modified phosphogypsum, is prepared as follows: industrial by-product phosphogypsum is crushed and passed through a 200-mesh sieve; a 5%-10% (w / w) calcium hydroxide aqueous solution is added at a liquid-to-solid ratio of 1.5-2:1; the mixture is stirred and reacted at 40-60℃ for 60-90 minutes; after filtration and washing until neutral, it is dried at 105-120℃; then, 1%-3% (by dry weight of the phosphogypsum) of calcium stearate is added; and the surface is modified at 80-100℃. The modified red mud is prepared by: crushing Bayer process red mud through a 300-mesh sieve, adding 10%-15% dilute sulfuric acid (liquid-solid ratio 2-3:1), activating it with acid at 50-70℃ for 90-120 minutes, filtering and washing until neutral, drying, adding 2%-5% of silane coupling agent KH550 (by dry weight of red mud), and grafting it at 90-110℃ for 45-60 minutes.

4. The low-carbon cement grinding aid composition according to claim 1, characterized in that, The modified amine complex, by weight, consists of 4-5 parts of diethanol monoisopropanolamine, 2-3 parts of triisopropanolamine, and 1 part of glucosamine, and the free amine content in the complex is ≤0.5%, with a viscosity of 150-300 mPa·s at 25°C.

5. The low-carbon cement grinding aid composition according to claim 1, characterized in that, The chelating activation component, by weight, consists of 1-2 parts of aminotrimethylenephosphonic acid, 3-4 parts of sodium citrate, and 2-3 parts of layered sodium silicate. The chelating capacity of this component for phosphorus and fluoride ions is ≥150mg / g, and the 7-day activity activation coefficient for cementitious admixtures is ≥1.

15.

6. The low-carbon cement grinding aid composition according to claim 1, characterized in that, The composition is a liquid. When left to stand for 90 days at 25°C in a closed environment, it shows no stratification, precipitation, or flocculation. The solid content is 45%-55%, and the pH value is 9.5-10.

5.

7. A preparation process for a low-carbon cement grinding aid composition according to any one of claims 1-6, characterized in that, Includes the following steps: Preparation of S1 bio-based modified xylan: Xylan is obtained by enzymatic hydrolysis and purification of corn cob or sugarcane bagasse with cellulase, followed by alkalization, carboxymethylation graft modification and post-treatment to obtain bio-based modified xylan with a degree of substitution of 0.6-1.2 for later use. Preparation of S2 modified composite solid waste filler: Modified phosphogypsum was prepared by defluorination, dephosphorization activation, and surface modification of industrial by-product phosphogypsum. Modified red mud was prepared by acid dissolution activation and coupling agent grafting modification of Bayer process red mud. The modified phosphogypsum and modified red mud were compounded in a certain proportion and ground until the specific surface area was ≥600 m². 2 / kg, to prepare modified composite solid waste filler for later use; Preparation of premixed S3 base mother liquor: Add the low-carbon polyol system and deionized water to the reactor according to the ratio, stir for 10-20 min at room temperature and pressure and a speed of 80-120 r / min, then add the modified alkanolamine complex and chelating activation component according to the ratio, heat to 35-50℃, and stir for 20-40 min to obtain a uniform base mother liquor; S4 final product composite homogenization: The bio-based modified xylan obtained from S1 and the modified composite solid waste filler obtained from S2 are added to the basic mother liquor of S3. Stir for 40-60 minutes at room temperature and pressure and a speed of 150-200 r / min. After stirring, let stand for 20-30 minutes to mature. Filter to remove insoluble impurities to obtain the low-carbon cement grinding aid composition.

8. The preparation process of the low-carbon cement grinding aid composition according to claim 7, characterized in that, In step S1, the enzymatic hydrolysis and purification process of xylan is as follows: corn cobs or sugarcane bagasse are crushed to 40-60 mesh, deionized water is added to prepare a slurry with a solid content of 10%-15%, cellulase is added at 1.5%-3% of the dry basis raw material mass, the pH of the system is adjusted to 4.5-5.5, and enzymatic hydrolysis is carried out at 45-55℃ for 24-48 hours. After enzymatic hydrolysis, the enzyme is inactivated, filtered, decolorized, concentrated, precipitated with alcohol, and dried to obtain xylan with a purity ≥95%.

9. The preparation process of the low-carbon cement grinding aid composition according to claim 7, characterized in that, In step S2, the mass ratio of modified phosphogypsum to modified red mud is 3:

1. The mixture is ground using a vertical sand mill with zirconia beads as the grinding media. The grinding speed is 1200-1500 r / min and the grinding time is 30-60 min. The particle size D90 of the final modified composite solid waste filler is ≤10 μm.

10. The preparation process of the low-carbon cement grinding aid composition according to claim 7, characterized in that, After the preparation of the basic mother liquor in step S3 is completed, the insoluble matter content of the system is detected and controlled to be ≤0.1% before proceeding to the next process. In step S4, the temperature of the system is controlled at 25-40℃ throughout the composite homogenization process. After stirring, the system is filtered under negative pressure through a 100-mesh filter. The fluctuation value of the batch-to-batch grinding system hourly output of the final product is ≤3%. The entire preparation process adopts reaction conditions of normal pressure and reaction temperature not exceeding 120℃. The water recycling rate in the production process is ≥95%. No organic solvents are added in the production process, and no industrial solid waste is generated.

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