High-iron-phase high-strength cement clinker and preparation method thereof

Abstract

The invention discloses a high-iron-phase high-strength cement clinker and a preparation method thereof, and belongs to the field of cement clinker preparation. The cement clinker takes white mud, a waste desulfurizer, steel slag fine powder and blast furnace slag as raw materials, and is prepared by the following steps: dispersing with ethylene glycol, carrying out microwave treatment, adding calcium oxide, reacting at 50-75 DEG C, co-grinding with fly ash, purifying, and modifying high-activity acryloyl chloride to obtain a waste activator; and finally, the mixture is mixed with raw materials such as Hummers-method graphene oxide, limestone and the like, so that the water reducing agent is prepared. The prepared cement clinker is high in solid waste utilization rate, the early-stage compressive strength is larger than 55 MPa, the problem that in the prior art, the early-stage strength of a high-iron-phase cement clinker is insufficient is solved to a certain extent, meanwhile, the corrosion resistance of the cement clinker is enhanced by means of an intercalated organic reagent, the service life of the cement clinker is prolonged, the 180-day seawater corrosion attenuation rate is smaller than 10%, and the cement clinker has the good comprehensive performance. The method can be suitable for preparation of high-strength cement in various scenes.

Description

Technical Field

[0001] This invention belongs to the field of cement clinker preparation technology, and particularly relates to a high-iron phase high-strength cement clinker and its preparation method. Background Technology

[0002] Slag and steel slag generated during industrial production are alkaline water-quenched slags that have undergone high-temperature roasting and have good gradation. Currently, there is no effective method for treating these waste slags; they are generally stored in open-air piles, requiring land and management, while the SO3 in the slags volatilizes into the air and dissolves into the soil, causing environmental pollution. Because slag is not as widespread as fly ash, coal gangue, or steel slag, and is a relatively regional mineral resource, its utilization has not received much attention. The research and application of high-ferrous phase cement clinker is primarily aimed at addressing the performance shortcomings of traditional cement clinker, the need for industrial solid waste resource utilization, and the development trend of low-carbon building materials.

[0003] Traditional silicate cement clinker is mainly composed of tricalcium silicate (C3S) and dicalcium silicate (C2S), with a tetracalcium aluminoferrite (C4AF, ferric phase core) content of only 5%-10%. It has shortcomings such as poor erosion resistance, easy decomposition of hydration products in sulfate and chloride ion environments, difficulty in balancing early strength and later strength, reliance on C3S to improve early strength can easily lead to concentrated heat release during hydration, while reducing C3S results in slow growth of later strength, high energy consumption and carbon emissions, and the need for high temperature of 1450-1550℃ for calcination, with carbon emissions exceeding 800kg per ton of clinker. It is difficult to meet the needs of high-end projects. Meanwhile, industrial solid wastes such as steel slag and blast furnace slag are rich in Fe2O3 and Al2O3. For example, steel slag contains 15%-25% Fe2O3 and blast furnace slag contains 10%-18% Al2O3, which are high-quality raw materials for generating C4AF. However, they have long been treated by stockpiling, which not only occupies land but also poses environmental risks. Promoting the synergistic utilization of solid waste and ferrous phase has become an inevitable direction. Ferrous phase clinker can improve impermeability and erosion resistance and balance early strength and exothermic reaction due to C4AF, and is gradually moving from laboratory to industrial application. Ferrous phase cement clinker hydration is significantly slowed down, and early strength is significantly reduced. If the amount of silicate in cement is not properly controlled, ettringite of different sizes will be converted into monosulfide hydrated calcium sulfoaluminate, which may aggravate the risk of microcracks inside concrete and affect impermeability and durability in the long term. Summary of the Invention

[0004] To address the problems of poor early-stage strength and brittleness in high-ferrous phase cement clinker in existing technologies, this invention proposes a high-strength high-ferrous phase cement clinker and its preparation method. The following technical solution is adopted to achieve the objectives of this invention: This invention proposes a method for preparing high-strength cement clinker with high ferrous phase, comprising the following steps: S1. Waste Activation At room temperature, white mud, waste desulfurizing agent, fine steel slag powder, and blast furnace slag are dissolved and mixed in ethylene glycol and then placed in a microwave reactor. The mixture is treated with a microwave radiation power of 100-220W and a microwave frequency of 700-2000MHz for 20-30 minutes. After cooling, calcium oxide and ethylene glycol are added, and the temperature is raised to 50-75℃. Fly ash is then added, and the activated material and fly ash are ground to 250-340 mesh. The mixture is then soaked in ethylene glycol, heated, cooled, and dried to obtain activated waste material. The main components of the white mud are CaCO3, which can slowly release Ca... 2+ It replenishes calcium and regulates the alkalinity of the system, while its fine particles improve the homogeneity of the mixture. CaCO3→CaO+CO2↑ CaO + H₂O → Ca(OH)₂ Waste desulfurizing agents often contain sulfates such as CaSO4, which provide SO4. 2- It reacts with the aluminum phase to form ettringite, enhancing early strength and simultaneously regulating the hydration reaction rate; fine steel slag powder mainly provides components such as CaO and Fe2O3, among which Fe2O3 can promote the formation of high-ferric phases, such as C4AF, improving the erosion resistance and strength of clinker; blast furnace slag, as one of the core raw materials, provides basic components such as SiO2, Al2O3, and CaO, and is the main source for the formation of silicates, aluminates, and other cementing minerals; the glassy structure is destroyed after microwave radiation, exposing internal active sites, making it easier to react with subsequent components such as calcium oxide. , High dosage can exert a filling effect, optimize the particle size distribution of the system, and improve the compactness of the activating components. Ethylene glycol can be used as a solvent to dissolve the above raw materials and can also serve as a dispersion medium to reduce the interfacial tension between raw materials, promote the uniform transfer of microwave energy, and enhance the destructive effect on the mineral structure. Ethanol soaking can remove impurities and soluble salts from the surface of the raw materials, and at the same time, it can adjust the pore structure of the materials during the heating and drying process, thereby improving the reactivity with cement clinker. Under microwave radiation conditions of 100-220W power and 700-2000MHz frequency, polar molecules in raw materials such as white mud, waste desulfurizing agent, steel slag fine powder, and blast furnace slag—substances containing hydroxyl groups and polar bonds—vibrate rapidly, generating heat through intermolecular friction. This achieves uniform heating inside the material, avoiding the temperature gradient problem of traditional heating methods and ensuring efficient heat transfer to the interior of the particles. Microwave treatment can also weaken the chemical bond energy on the surface of mineral particles, reduce the activation energy of subsequent grinding and reaction, making it easier for the raw materials to achieve the fineness requirement of 250-340 mesh during subsequent grinding, and further enhance their reactivity with other components. This uniform heating can destroy the glassy structure and crystal arrangement of the raw materials, especially steel slag and blast furnace slag, causing defects in the crystal lattice of originally stable aluminosilicates, ferrites and other minerals, increasing the specific surface area and exposing more active sites, creating conditions for subsequent reactions with components such as calcium oxide; after adding calcium oxide (a strongly alkaline substance), under mild heating conditions of 50-75℃, it can undergo a preliminary reaction with the active SiO2 and Al2O3 in the microwave-treated slag and steel slag, generating precursors such as low-crystallinity hydrated calcium silicate and hydrated calcium aluminate. These products act as active bridges, enhancing the compatibility with the cement system; at the same time, the high-alkaline environment provided by calcium oxide can further destroy the inert layer on the mineral surface, promoting the generation of more active ions (Ca). 2 + Si 4+ Al 3+ Dissolution.

[0005] S2. Modified activator Slag, tetrahydrofuran, and triethylamine were placed in an Erlenmeyer flask and fixed on a magnetic stirrer. The stirrer was turned on and the speed adjusted to a moderate level. Acryloyl chloride was slowly added dropwise to the Erlenmeyer flask containing the slag through a constant-pressure dropping funnel, controlling the dropping rate to complete the process within 15-20 minutes. During the dropping process, the temperature of the reaction system was carefully observed. If the temperature rose too quickly, the dropping was stopped and resumed only after the temperature stabilized. After the dropping was complete, the reaction was stirred for 2-3 hours. An appropriate amount of anhydrous sodium sulfate was added to the transferred clear liquid, and the mixture was stirred for 15-20 minutes. The mixture was then filtered to remove the anhydrous sodium sulfate and its adsorbed water and other impurities. The filtrate was then rotary evaporated at 40-50℃ and vacuum dried for 12 hours to obtain the modified activator. The surface of the slag, due to the previous activation... The slag contains a large number of hydroxyl groups (-OH), including silanol (≡Si-OH) and aluminumol (≡Al-OH). These hydroxyl groups are nucleophilic sites for the reaction. Anhydrous tetrahydrofuran (THF), as an aprotic polar solvent, can dissolve acryloyl chloride and disperse slag particles, increasing the solid-liquid contact area. Triethylamine is an organic amine acid-binding agent, and its alkalinity can neutralize the HCl generated in the reaction, preventing HCl from reacting with the hydroxyl groups on the slag surface, and also preventing HCl from corroding equipment or causing side reactions with acryloyl chloride. The acyl chloride group (-COCl) in acryloyl chloride (CH2=CH-COCl) is a strong electrophilic center. The hydroxyl groups (-OH) on the slag surface act as nucleophiles, using their lone pair electrons to attack the acyl chloride carbon, resulting in a nucleophilic substitution reaction and generating a cement activator with double bonds. .

[0006] S3. Copolymerization reaction The modified activator obtained from S2, ethylene glycol monovinyl polyethylene glycol ether, 2-acrylamide-2-methylpropanesulfonic acid, itaconic acid, and an appropriate amount of deionized water were placed into a 250 mL reactor equipped with a stirrer. The reactor was stirred at 60 °C and 60 r / min until the ethylene glycol monovinyl polyethylene glycol ether was completely dissolved. At this point, a 30% (w / w) H2O2 solution was added, and stirring was continued for 15 min. Simultaneously, acrylic acid was added dropwise at a uniform rate for 1 h. After the addition, stirring was continued, and the reactor was kept at 60 °C for 3 h. Then, a 30% (w / w) NaOH aqueous solution was added to adjust the pH to 6-7, resulting in the waste residue of the grafted water-reducing agent. .

[0007] S4. Preparation of high-strength cement clinker with high ferrophase S401. Preparation of graphene oxide Graphite powder and NaNO3 powder were added to a 1000 mL round-bottom flask. Then, 100 mL of concentrated H2SO4 was slowly added under ice bath conditions. After 4 hours, KMnO4 was slowly added and stirred until completely dissolved in the flask. The sample was then immersed in an ice bath for 20 minutes. The flask was then removed from the ice bath and stirred continuously at room temperature for 24 hours. The resulting mixture was then mixed with 200 mL of deionized water and stirred at 0°C for 20 minutes to form a dispersion. 10 mL of H2O2 was then slowly added using a pipette to dissolve the dispersion. The resulting dispersion was filtered through a Buchner funnel, and 20 mL of hydrochloric acid solution was transferred to the flask with the SO42-. 2- The reaction was followed by continuous stirring with ultrapure water for 4 days to remove some metal ions and residual acidic substances. Finally, the prepared graphene oxide solution was purified by centrifugation four times and repeatedly filtered under vacuum until the pH reached neutral, yielding graphene oxide. This reaction is a typical modification process for preparing graphene oxide (GO) using the Hummers method. Graphite powder serves as the substrate material, and its layered structure consists of carbon atoms separated by sp... 2 Hybridization forms a six-membered ring, with interlayer connections via weak van der Waals forces, providing a basis for subsequent oxidation and stripping; NaNO3 acts as an intercalating agent and auxiliary oxidant, and its nitrate ions NO 3- It can insert into the graphite interlayer, weakening the interlayer forces, and simultaneously generate a small amount of nitric acid (HNO3) in concentrated sulfuric acid medium, enhancing the oxidizing power of the oxidation system. Concentrated H2SO4 acts as both a solvent and a proton donor, further inserting into the graphite interlayer through protonation, expanding the interlayer spacing; at the same time, it provides a strongly acidic environment, promoting the dissolution and activity of the oxidant.

[0008] Under ice bath conditions (around 0°C), the reaction between NaNO3 and concentrated H2SO4 to generate toxic NO2 gas is suppressed by low temperature. This also prevents the subsequent addition of KMnO4 from decomposing due to intense exothermic reactions (as KMnO4 may decompose into MnO2 at high temperatures, reducing oxidation efficiency), ensuring a gentle and controllable pre-oxidation process. This also avoids localized over-oxidation that could lead to graphite sheet breakage. During the oxidation process, KMnO4 acts as the core strong oxidant, generating MnO2 in the concentrated sulfuric acid medium. 3+ Permanganate cations can attack defect sites at the edges of graphite, such as unsaturated carbon atoms, and initiate oxidation reactions: edge carbon atoms are oxidized to carboxyl groups (-COOH); carbon atoms in the interlayer and on the surface are oxidized to hydroxyl groups (-OH) and epoxy groups (-O-); the oxygen-containing functional groups generated by oxidation carry negative charges, which further expand the interlayer spacing of graphite through electrostatic repulsion, creating conditions for subsequent exfoliation.

[0009] After the reaction is complete, stir at room temperature for 24 hours to ensure a complete reaction and uniform distribution of functional groups between and on the graphite layers, while allowing MnO to react. 3+The active species penetrate deep into the interlayer space, achieving deep oxidation. By adding its deionized water, the epoxy groups in the graphite interlayers are hydrolyzed into vicinal diol structures (-OH), simultaneously diluting the acidity of the system and terminating excessive oxidation. Furthermore, the low temperature of 0℃ avoids excessively vigorous hydrolysis reactions that could lead to lamellar aggregation. At this point, H₂O₂ acts as a reducing agent, reducing excess KMnO₄ and the generated brownish-black MnO₂ in the system to soluble, colorless MnO₂. 2+ The reaction is: 2KMnO4+3H2O2+3H2SO4→K2SO4+2MnSO4+3O2↑+6H2O, thereby removing residual oxidant and avoiding damage to functional groups by oxidant during subsequent washing.

[0010] After filtration to obtain the dispersion, hydrochloric acid is added to the system to provide Cl⁻, which reacts with the residual Na⁻ in the system. + K + Mn 2+ The reaction produces soluble salts NaCl, KCl, and MnCl2, while also neutralizing some sulfate ions (SO4). 2- It produces HCl and HSO, which are easily soluble in water. 4- The impurities are removed by stirring and washing with ultrapure water. In addition, ultrapure water can gradually dissolve and remove soluble salts in the system, such as metal chlorides, sulfates and residual acids, through diffusion, thereby reducing the ionic strength of the solution. Continuous stirring ensures that impurities are fully removed from the surface and interlayer of the graphene oxide sheets, avoiding sheet aggregation caused by residual salts.

[0011] S402. Mixing Gypsum, limestone, and waste residue from the grafted water-reducing agent obtained from S3 were added to a planetary ball mill and dry-mixed at 200 r / min for 30 min. The mixture was then transferred to a twin-shaft mixer, where graphene oxide obtained from S401 was slowly added while stirring. Deionized water was added, and stirring was continued for 45-60 min. The mixed material was then loaded into a mold and pressed into cylindrical test blocks under a pressure of 20-30 MPa. The blocks were left to stand at room temperature for 24 h. After demolding, the test blocks were placed in a muffle furnace and heated to 200℃ at a rate of 5℃ / min, held for 1 h, and then heated to 1300-1400℃ at a rate of 10℃ / min, held for 2-3 h, and allowed to cool naturally to room temperature. The blocks were then crushed and ground in a ball mill to a specific surface area of ​​350-450 m² / kg to obtain high-iron phase high-strength cement clinker. Clinker calcination and mineral formation: The mixed raw materials are fed into a rotary kiln and calcined at a high temperature of 1450-1550℃. Limestone decomposes into CaO, which reacts with SiO2 in slag / steel slag to form C3S and C2S. Fe2O3 in steel slag reacts with CaO and Al2O3 to form C4AF, and its content increases due to the incorporation of steel slag, enhancing its erosion resistance. Gypsum provides SO4. 2-The modified graphene reacts with C3A to form ettringite, which regulates the setting time and supplements early strength. Before calcination, the modified graphene is uniformly dispersed in the raw materials, remains stable at high temperatures, and fills the micropores after the clinker cools, optimizing structural density. After grinding and finishing, the calcined clinker is rapidly cooled in a cooler to prevent C3S decomposition, mixed with water-reducing agents and residual gypsum, and then ground in a ball mill to the specified fineness, achieving a specific surface area of ​​300-450 m² / g. 2 / kg. The water-reducing agent plays a dispersing role at this stage, ensuring uniform distribution of clinker particles, ultimately forming high-iron, high-strength cement clinker. Limestone decomposes into CaO and CO2 at high temperatures, providing core calcareous raw materials for subsequent mineral formation. ; When the temperature rises to 1450-1550℃, this stage is a crucial step in the formation of cement clinker minerals. CaO reacts with active components such as SiO2, Al2O3, and Fe2O3 in steel slag and blast furnace slag to generate core strength minerals such as calcium silicate and calcium aluminoferrite. CaO reacts with SiO2 in blast furnace slag / steel slag at high temperatures to generate C3S, which is the main source of cement's later strength. ; Some SiO2 reacts with CaO to form C2S, which has low strength in the early stage, but the strength continues to increase in the later stage. ; The Fe2O3 abundant in steel slag reacts with CaO and Al2O3 (from slag / steel slag) to form C4AF. The increased content of C4AF due to the addition of steel slag enhances the erosion resistance of cement. , Al2O3 in slag / steel slag reacts with CaO to form C3A, which then reacts with gypsum to adjust the setting time. , The gypsum added during grinding (mainly composed of CaSO4·2H2O, or calcined gypsum CaSO4·0.5H2O from the initial activator) reacts with C3A to form ettringite (3CaO·Al2O3·3CaSO4·32H2O), which can delay setting time and supplement early strength; 3CaO·Al2O3 + CaSO4·2H2O + 26H2O → 3CaO·Al2O3·3CaSO4·32H2O (ettringite) Preferably, the steel slag and blast furnace slag used are purchased from Jingye Group Co., Ltd., and are in the form of white powder with a specific surface area of ​​350 m². 2 / kg, 28d activity index greater than 105%, mass coefficient K = 2.07 > 1.2, alkalinity coefficient B = 1.14 > 1, belonging to alkaline slag; the components and their corresponding percentages in the system are shown in Table 1: Table 1 Percentage of blast furnace slag and steel slag fine powder in the system (%) Preferably, the raw materials used in S1 are: 45-55 parts steel slag fine powder, 45-55 parts blast furnace slag, 5-8 parts fly ash, and 1-2 parts calcium oxide.

[0012] Preferably, the white mud is one of papermaking white mud and alkali production white mud, and the waste desulfurizing agent is a deactivated solid calcium-based desulfurizing agent, which comes from the dry desulfurization process and is in powder, columnar and clover-shaped form; the waste desulfurizing agent contains 5-15% Ca(OH)2, 10-25% CaSO3 and 60-75% CaSO4.

[0013] Preferably, the raw materials used in S2 are characterized by having a mass ratio of 15-45 parts for the inorganic activating component and the organic activating component.

[0014] Preferably, the molar ratio of the raw materials used in S3 is: the modified activator obtained in S2: ethylene glycol monovinyl polyethylene glycol ether: 2-acrylamide-2-methylpropanesulfonic acid: itaconic acid: acrylic acid = 1: 3.5-4.0: 0.8-1.2: 0.9-1.1: 1.2-1.3, wherein the molecular weight of ethylene glycol monovinyl polyethylene glycol ether is 600.

[0015] Preferably, the raw materials used in the preparation of modified graphene in S401 are: 2-3 parts graphite powder, 3-4 parts NaNO3, and 6-7 parts KMnO4 by mass.

[0016] Preferably, the amount of water added in S402 needs to be controlled at a system moisture content of 12%-15%.

[0017] Preferably, the prepared cement clinker has a high solid waste utilization rate, an early compressive strength >55MPa, and a seawater corrosion attenuation rate <10% after 180 days, making it suitable for the preparation of high-strength cement in various scenarios.

[0018] The beneficial effects of this invention are as follows: (1) The waste activator synthesized in this invention has inorganic components that undergo microwave pretreatment to destroy the glassy structure of slag and steel slag, exposing a large number of active sites. Combined with the alkaline environment provided by calcium oxide, it can efficiently release active ions. The complex alkanolamine in the organic components further promotes its dissolution through complexation and penetration, while CTAB optimizes dispersibility. The two work synergistically to transform the originally inert solid waste into an effective component that can participate in the gelation reaction, significantly improving the dosage and utilization efficiency of waste such as steel slag and slag. The Ca added by the white mud 2+ The optimization of clinker mineral composition by combining silicon and aluminum components with blast furnace slag improves the formation efficiency of strength minerals such as C3S and C2S, regulates the hydration reaction rate, avoids rapid setting or delayed strength development, and makes the mechanical properties of clinker more stable.

[0019] (2) This invention synthesizes a water-reducing agent, which efficiently disperses cement particles through electrostatic repulsion and steric hindrance, significantly reducing water consumption. At the same time, the amide group enhances the adsorption capacity of cement particles, preventing particle agglomeration and significantly improving the fluidity of cement slurry. Furthermore, the vinyltriethoxysilane side chain is hydrolyzed to generate silanol, which can react with the cement surface to form CSH gel, shortening the hydration induction period, and can also reduce the loss of mortar fluidity over time through chemical adsorption, solving the problem of poor slump retention of traditional water-reducing agents and ensuring the stability of slurry workability during construction.

[0020] (3) This invention uses intercalated graphene oxide, which introduces a large number of oxygen-containing functional groups on its surface during the oxidation process, thereby enhancing its interfacial bonding ability with the matrix material, reducing interfacial defects, and thus improving the mechanical properties of the composite material, including tensile strength, flexural strength and hardness, effectively improving the problem of insufficient strength in the early stage of high-iron phase cement clinker, with an early compressive strength >55MPa; furthermore, the sheet-like structure and surface functional groups of modified graphene can form physical barriers and chemical adsorption in the composite material, slowing down the penetration rate of external corrosive media, improving the corrosion resistance and durability of the material, with a performance decay rate of <10% in the 180d seawater corrosion test.

[0021] (4) Most of the raw materials used in this invention are derived from slag solid waste generated during industrial production. The key elements such as silicon, aluminum, calcium, and iron contained in this type of solid waste are highly compatible with the core components required for cement clinker preparation, and production needs can be met without the need to introduce large amounts of natural mineral raw materials. This waste-for-material design not only reduces the dependence on the exploitation of natural resources from the source and significantly reduces the cost of raw material procurement and processing, but also provides a practical and feasible technical path for the green and low-carbon development of the building materials industry. Attached Figure Description

[0022] Figure 1 The image shows the hydrogen nuclear magnetic resonance spectrum of the waste residue of the grafted water-reducing agent used in Example 1. Detailed Implementation

[0023] The technical solution and its effects of the present invention will be further described below with reference to the accompanying drawings in the embodiments of the present invention. The following embodiments are only for illustrating the content of the present invention and are not intended to limit the scope of protection of the present invention. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0024] The sources of the materials used in the following examples and comparative examples are as follows: Steel slag fine powder: Jingye Group Co., Ltd.; Blast furnace slag: Jingye Group Co., Ltd.; Limestone: Jiangsu Huifeng Bio-Agriculture Co., Ltd.; Gypsum: Tianjin Guangcheng Chemical Technology Co., Ltd.; White mud: Tianjin Guangcheng Chemical Technology Co., Ltd.; Waste desulfurizing agent: Tianjin Guangcheng Chemical Technology Co., Ltd.; Ethylene glycol: Shanghai Aladdin Technology Co., Ltd.; Calcium oxide: Tianjin Guangcheng Chemical Technology Co., Ltd.; Fly ash: Tianjin Guangcheng Chemical Technology Co., Ltd.; N-tert-butyldiethanolamine: Hangzhou Jessica Chemical Co., Ltd.; Isopropanolamine: Tianjin Guangcheng Chemical Technology Co., Ltd.; Hexadecyltrimethylammonium bromide: Hangzhou Jessica Chemical Co., Ltd.; Acrylic acid: Tianjin Guangcheng Chemical Technology Co., Ltd.; 3-Mercaptopropionic acid: Shanghai Aladdin Technology Co., Ltd.; Ascorbic acid: Shanghai Aladdin Technology Co., Ltd.; Ethylene glycol monovinyl polyethylene glycol ether: Shanghai Aladdin Technology Co., Ltd.; 2-Acrylamide-2-methylpropanesulfonic acid: Shanghai Aladdin Technology Co., Ltd.; Itaconic acid: Shanghai Aladdin Technology Co., Ltd.; Deionized water: homemade.

[0025] Examples 1-3 and Comparative Examples 1-5 all consistently employ the synthesis method of high-strength cement clinker with high iron phase as described in the invention.

[0026] Example 1 S1. Waste Activation At room temperature, white mud, waste desulfurizing agent, fine steel slag powder, and blast furnace slag are dissolved and mixed in ethylene glycol and then placed in a microwave reactor. The mixture is treated with microwave radiation power of 100-220W and microwave frequency of 700-2000MHz for 20-30 minutes. After cooling, calcium oxide and ethylene glycol are added, the temperature is raised to 50-75℃, fly ash is added, and the active material and fly ash are ground to 250-340 mesh. The activated waste material is then obtained by soaking in ethylene glycol, heating, cooling, and drying. S2. Modified activator Slag, tetrahydrofuran, and triethylamine were placed in an Erlenmeyer flask and fixed on a magnetic stirrer. The stirrer was turned on and the speed was adjusted to a moderate level. Acryloyl chloride was slowly added dropwise to the Erlenmeyer flask containing slag through a constant pressure dropping funnel. The dropping rate was controlled so that the dropping process was completed within 15-20 minutes. During the dropping process, the temperature change of the reaction system was carefully observed. If the temperature rose too quickly, the dropping was stopped and continued after the temperature stabilized. After the dropping was completed, the reaction was stirred for 2-3 hours. An appropriate amount of anhydrous sodium sulfate was added to the clear liquid after the reaction was transferred, and the mixture was stirred for 15-20 minutes. The mixture was then filtered to remove anhydrous sodium sulfate and impurities such as water that it had adsorbed. The filtrate was then evaporated by rotary evaporation at 40-50℃ and dried under vacuum for 12 hours to obtain the modified activator. S3. Copolymerization reaction 200g of the modified activator obtained from S2, 60g of ethylene glycol monovinyl polyethylene glycol ether, 7.3g of 2-acrylamide-2-methylpropanesulfonic acid, 13g of itaconic acid, and an appropriate amount of deionized water were placed into a 250mL reactor equipped with a stirrer. The mixture was stirred at 60℃ and 60r / min until the ethylene glycol monovinyl polyethylene glycol ether was completely dissolved. At this point, a 30% (w / w) H2O2 solution was added, and stirring continued for 15min. Simultaneously, acrylic acid was added dropwise at a uniform rate over 1h. After the addition, stirring continued, and the mixture was kept at 60℃ for 3h. Then, a 30% (w / w) NaOH aqueous solution was added to adjust the pH to 6-7, yielding the waste residue of the grafted water-reducing agent. Its 1H NMR spectrum is shown below. Figure 1 As shown; S4. Preparation of high-strength cement clinker with high ferrophase S401. Preparation of graphene oxide Graphite powder and NaNO3 powder were added to a 1000 mL round-bottom flask. Then, 100 mL of concentrated H2SO4 was slowly added under ice bath conditions. After 4 hours, KMnO4 was slowly added and stirred until completely dissolved in the flask. The sample was then immersed in an ice bath for 20 minutes. The flask was then removed from the ice bath and stirred continuously at room temperature for 24 hours. The resulting mixture was then mixed with 200 mL of deionized water and stirred at 0°C for 20 minutes to form a dispersion. 10 mL of H2O2 was then slowly added using a pipette to dissolve the dispersion. The resulting dispersion was filtered through a Buchner funnel, and 20 mL of hydrochloric acid solution was transferred to the flask with the SO42-.2- The reaction was carried out, and then the solution was continuously stirred with ultrapure water for 4 days to remove some metal ions and residual acidic substances. Finally, the prepared graphene oxide solution was purified by centrifugation four times and vacuum filtration was repeated until the pH reached neutral to obtain graphene oxide. S402. Mixing Add 2g of gypsum, 4g of limestone, and 250g of waste residue from the grafted water-reducing agent obtained from S3 to a planetary ball mill. Dry mix at 200r / min for 30min. Then transfer to a twin-shaft mixer, and slowly add 30g of graphene oxide obtained from S401 while stirring. Add deionized water and continue stirring for 45-60min. Load the mixed material into a mold and press it into cylindrical specimens under a pressure of 20-30MPa. Let it stand at room temperature for 24h. After demolding, place the specimens in a muffle furnace and heat to 200℃ at a rate of 5℃ / min, hold for 1h, and then continue heating to 1300-1400℃ at a rate of 10℃ / min, hold for 2-3h, and allow to cool naturally to room temperature. Crush the specimens and grind them in a ball mill to a specific surface area of ​​350-450m² / kg to obtain high-iron phase high-strength cement clinker. At this time, the proportion of each component in the cement clinker is: .

[0027] Example 2 S1. Waste Activation At room temperature, white mud, waste desulfurizing agent, fine steel slag powder, and blast furnace slag are dissolved and mixed in ethylene glycol and then placed in a microwave reactor. The mixture is treated with microwave radiation power of 100-220W and microwave frequency of 700-2000MHz for 20-30 minutes. After cooling, calcium oxide and ethylene glycol are added, the temperature is raised to 50-75℃, fly ash is added, and the active material and fly ash are ground to 250-340 mesh. The activated waste material is then obtained by soaking in ethylene glycol, heating, cooling, and drying. S2. Modified activator Slag, tetrahydrofuran, and triethylamine were placed in an Erlenmeyer flask and fixed on a magnetic stirrer. The stirrer was turned on and the speed was adjusted to a moderate level. Acryloyl chloride was slowly added dropwise to the Erlenmeyer flask containing slag through a constant pressure dropping funnel. The dropping rate was controlled so that the dropping process was completed within 15-20 minutes. During the dropping process, the temperature change of the reaction system was carefully observed. If the temperature rose too quickly, the dropping was stopped and continued after the temperature stabilized. After the dropping was completed, the reaction was stirred for 2-3 hours. An appropriate amount of anhydrous sodium sulfate was added to the clear liquid after the reaction was transferred, and the mixture was stirred for 15-20 minutes. The mixture was then filtered to remove anhydrous sodium sulfate and impurities such as water that it had adsorbed. The filtrate was then evaporated by rotary evaporation at 40-50℃ and dried under vacuum for 12 hours to obtain the modified activator. S3. Copolymerization reaction The modified activator obtained from S2, ethylene glycol monovinyl polyethylene glycol ether, 2-acrylamide-2-methylpropanesulfonic acid, itaconic acid, and an appropriate amount of deionized water were placed into a 250 mL reactor equipped with a stirrer. The reactor was stirred at 60 °C and 60 r / min until the ethylene glycol monovinyl polyethylene glycol ether was completely dissolved. At this point, a 30% (w / w) H2O2 solution was added, and stirring was continued for 15 min. Simultaneously, acrylic acid was added dropwise at a uniform rate for 1 h. After the addition, stirring was continued, and the reactor was kept at 60 °C for 3 h. Then, a 30% (w / w) NaOH aqueous solution was added to adjust the pH to 6-7, resulting in the waste residue of the grafted water-reducing agent. S4. Preparation of high-strength cement clinker with high ferrophase S401. Preparation of graphene oxide Graphite powder and NaNO3 powder were added to a 1000 mL round-bottom flask. Then, 100 mL of concentrated H2SO4 was slowly added under ice bath conditions. After 4 hours, KMnO4 was slowly added and stirred until completely dissolved in the flask. The sample was then immersed in an ice bath for 20 minutes. The flask was then removed from the ice bath and stirred continuously at room temperature for 24 hours. The resulting mixture was then mixed with 200 mL of deionized water and stirred at 0°C for 20 minutes to form a dispersion. 10 mL of H2O2 was then slowly added using a pipette to dissolve the dispersion. The resulting dispersion was filtered through a Buchner funnel, and 20 mL of hydrochloric acid solution was transferred to the flask with the SO42-. 2- The reaction was carried out, and then the solution was continuously stirred with ultrapure water for 4 days to remove some metal ions and residual acidic substances. Finally, the prepared graphene oxide solution was purified by centrifugation four times and vacuum filtration was repeated until the pH reached neutral to obtain graphene oxide. S402. Mixing Add 2g of gypsum, 4g of limestone, and 260g of waste residue from the grafted water-reducing agent obtained from S3 to a planetary ball mill. Dry mix at 200r / min for 30min. Then transfer to a twin-shaft mixer, and slowly add 25g of graphene oxide obtained from S401 while stirring. Add deionized water and continue stirring for 45-60min. Load the mixed material into a mold and press it into cylindrical specimens under a pressure of 20-30MPa. Let it stand at room temperature for 24h. After demolding, place the specimens in a muffle furnace and heat to 200℃ at a rate of 5℃ / min, hold for 1h, and then continue heating to 1300-1400℃ at a rate of 10℃ / min, hold for 2-3h, and allow to cool naturally to room temperature. Crush the specimens and grind them in a ball mill to a specific surface area of ​​350-450m² / kg to obtain high-iron phase high-strength cement clinker. At this time, the proportion of each component in the cement clinker is: .

[0028] Example 3 S1. Waste Activation At room temperature, white mud, waste desulfurizing agent, fine steel slag powder, and blast furnace slag are dissolved and mixed in ethylene glycol and then placed in a microwave reactor. The mixture is treated with microwave radiation power of 100-220W and microwave frequency of 700-2000MHz for 20-30 minutes. After cooling, calcium oxide and ethylene glycol are added, the temperature is raised to 50-75℃, fly ash is added, and the active material and fly ash are ground to 250-340 mesh. The activated waste material is then obtained by soaking in ethylene glycol, heating, cooling, and drying. S2. Modified activator Slag, tetrahydrofuran, and triethylamine were placed in an Erlenmeyer flask and fixed on a magnetic stirrer. The stirrer was turned on and the speed was adjusted to a moderate level. Acryloyl chloride was slowly added dropwise to the Erlenmeyer flask containing slag through a constant pressure dropping funnel. The dropping rate was controlled so that the dropping process was completed within 15-20 minutes. During the dropping process, the temperature change of the reaction system was carefully observed. If the temperature rose too quickly, the dropping was stopped and continued after the temperature stabilized. After the dropping was completed, the reaction was stirred for 2-3 hours. An appropriate amount of anhydrous sodium sulfate was added to the clear liquid after the reaction was transferred, and the mixture was stirred for 15-20 minutes. The mixture was then filtered to remove anhydrous sodium sulfate and impurities such as water that it had adsorbed. The filtrate was then evaporated by rotary evaporation at 40-50℃ and dried under vacuum for 12 hours to obtain the modified activator. S3. Copolymerization reaction 200g of the modified activator obtained from S2, 50g of ethylene glycol monovinyl polyethylene glycol ether, 6.4g of 2-acrylamide-2-methylpropanesulfonic acid, 12g of itaconic acid, and an appropriate amount of deionized water were placed into a 250mL reactor equipped with a stirrer. The mixture was stirred at 60℃ and 60r / min until the ethylene glycol monovinyl polyethylene glycol ether was completely dissolved. At this point, a 30% (w / w) H2O2 solution was added, and stirring was continued for 15min. Simultaneously, acrylic acid was added dropwise at a uniform rate for 1h. After the addition, stirring was continued, and the mixture was kept at 60℃ for 3h. Then, a 30% (w / w) NaOH aqueous solution was added to adjust the pH to 6-7, yielding the waste residue of the grafted water-reducing agent. S4. Preparation of high-strength cement clinker with high ferrophase S401. Preparation of graphene oxide Graphite powder and NaNO3 powder were added to a 1000 mL round-bottom flask. Then, 100 mL of concentrated H2SO4 was slowly added under ice bath conditions. After 4 hours, KMnO4 was slowly added and stirred until completely dissolved in the flask. The sample was then immersed in an ice bath for 20 minutes. The flask was then removed from the ice bath and stirred continuously at room temperature for 24 hours. The resulting mixture was then mixed with 200 mL of deionized water and stirred at 0°C for 20 minutes to form a dispersion. 10 mL of H2O2 was then slowly added using a pipette to dissolve the dispersion. The resulting dispersion was filtered through a Buchner funnel, and 20 mL of hydrochloric acid solution was transferred to the flask with the SO42-. 2-The reaction was carried out, and then the solution was continuously stirred with ultrapure water for 4 days to remove some metal ions and residual acidic substances. Finally, the prepared graphene oxide solution was purified by centrifugation four times and vacuum filtration was repeated until the pH reached neutral to obtain graphene oxide. S402. Mixing Add 2g of gypsum, 4g of limestone, and 240g of waste residue from the grafted water-reducing agent obtained from S3 to a planetary ball mill. Dry mix at 200r / min for 30min. Then transfer to a twin-shaft mixer, and slowly add 35g of graphene oxide obtained from S401 while stirring. Add deionized water and continue stirring for 45-60min. Load the mixed material into a mold and press it into cylindrical specimens under a pressure of 20-30MPa. Let it stand at room temperature for 24h. After demolding, put the specimens into a muffle furnace and heat them to 200℃ at a rate of 5℃ / min, hold for 1h, and then heat them to 1300-1400℃ at a rate of 10℃ / min, hold for 2-3h, and let them cool naturally to room temperature. Crush the specimens and grind them in a ball mill to a specific surface area of ​​350-450m² / kg to obtain high-iron phase high-strength cement clinker. At this time, the proportion of each component in the cement clinker is: .

[0029] Comparative Example 1 It is basically the same as Example 1, except that no alkaline activating component is used, that is, no substance other than blast furnace slag and steel slag fine powder is used in step S1.

[0030] Comparative Example 2 It is basically the same as Example 1, except that the activator is not modified, i.e., step S2 is missing.

[0031] Comparative Example 3 The process is basically the same as in Example 1, except that the copolymerization reaction does not use water-reducing agent components; that is, step S3 lacks acrylic acid, ethylene glycol monovinyl polyethylene glycol ether, 2-acrylamide-2-methylpropanesulfonic acid, and itaconic acid.

[0032] Comparative Example 4 It is basically the same as Example 1, except that graphene oxide is not used; that is, graphene oxide is not added in step S4.

[0033] Comparative Example 5 Cement clinker sold by Nantong Hantai Chemical Co., Ltd.

[0034] The products obtained in Examples 1-3 and Comparative Examples 1-5 were used to prepare high-strength cement clinker with high iron phase, including the following steps: After crushing, limestone is mixed with pretreated steel slag and blast furnace slag, and a waste activator is added. The mixture is then initially dispersed by mechanical stirring. The surface activity of hexadecyltrimethylammonium bromide and the penetrating effect of alkanolamines in the activator are utilized to activate inorganic components such as Ca... 2+ It rapidly penetrates the surface of slag / steel slag particles, disrupting their glassy structure and releasing Fe. 3+ Al 3+ Si 4+ Active ions; Clinker calcination and mineral formation: The mixed raw materials are fed into a rotary kiln and calcined at a high temperature of 1450-1550℃: Limestone decomposes into CaO, which reacts with SiO2 in slag / steel slag to generate C3S and C2S; Fe2O3 in steel slag reacts with CaO and A2O3 to generate C4AF, and the content is increased due to the incorporation of steel slag, enhancing erosion resistance; Gypsum provides SO4 2- The modified graphene reacts with C3A to form ettringite, which regulates the setting time and supplements early strength. Before calcination, the modified graphene is uniformly dispersed in the raw materials, remains stable at high temperatures, and fills the micropores after the clinker cools, optimizing structural density. After grinding and finishing, the calcined clinker is rapidly cooled in a cooler to prevent C3S decomposition, mixed with water-reducing agents and residual gypsum, and then ground in a ball mill to the specified fineness, achieving a specific surface area of ​​300-450 m² / g. 2 / kg. The water-reducing agent plays a dispersing role at this stage, ensuring that the clinker particles are evenly distributed, ultimately forming high-strength cement clinker with high iron phase.

[0035] The high-strength cement clinker 5 prepared in Examples 1-3 and Comparative Examples 1-5 were all subjected to the following tests; the test results are shown in Tables 2 and 3.

[0036] I. Mechanical Performance Testing (Core Performance Indicators) 1. Early and late strength tests Test standard: GB / T 17671-2021 "Test Method for Strength of Cement Mortar"; Test objective: To verify early strength characteristics and strength development trend; Test Method: 40mm×40mm×160mm cement mortar specimens (water-cement ratio 0.5, mortar-mortar ratio 1:3) were prepared according to standard procedures. Flexural and compressive strengths were measured at 3d, 7d, 28d, and 90d. Early strength was primarily assessed at 3d strength; long-term strength was assessed at the 28d and 90d growth rates (the later-stage strength growth rate of high-ferrous phase cement should be ≥5%). Correlation with Ferrous Phase Characteristics: C4AF hydration is rapid, which can accelerate early strength development, but it is necessary to avoid later-stage strength reduction due to concentrated hydration heat; therefore, 90-day strength needs to be monitored.

[0037] 2. Compressive strength and flexural strength Test standard: GB / T 17671-2021 "Test Method for Strength of Cement Mortar"; Compressive strength: The maximum load at which the specimen fails was determined using a pressure testing machine (accuracy ±1%) at a rate of 2400 N / s ± 200 N / s, and the compressive strength (unit: MPa) was calculated.

[0038] Flexural strength: The flexural strength (unit: MPa) was calculated by using a flexural testing machine (three-point bending method) with a loading rate of 50 N / s ± 10 N / s, recording the failure load.

[0039] 3. Other auxiliary tests for mechanical properties Splitting tensile strength: The tensile properties of cement paste (reflecting the material's ability to resist cracking) were determined according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".

[0040] Elastic modulus: The elastic modulus of cement stone at 28 days of age is determined using a dynamic elasticity tester or a static method to assess the material's deformation capacity under load.

[0041] Table 2 Mechanical property tests of cements prepared in Examples 1-3 and Comparative Examples 1-5 As shown in Table 2, the overall performance of Examples 1-3 is better than that of the comparative examples. Regarding the flexural and compressive strength of the cement at 3 days, Examples 1 and 3 are similar, while Example 2 shows a slight decrease. This may be because Example 2 has a higher iron phase content, resulting in a significant slowdown in cement clinker hydration and a marked reduction in early strength. The core reason is that the core products of iron phase mineral hydration, especially in the early stages, are ettringite and a small amount of monosulfide-type hydrated calcium sulfoaluminate. The formation rate and microstructure of these products directly determine the development of early strength. C3A undergoes rapid dissolution upon addition of water, releasing Al. 3+ and Ca 2+ C3A + 6H2O → 3CaO·Al2O3·6H2O, i.e., hydrated calcium aluminate; at this point, the gypsum (CaSO4·2H2O) added to the cement will quickly dissolve and provide SO4. 2- , with C4AH 13 Ca 2+ A secondary reaction occurs: 3CaO·Al₂O₃·6H₂O + 3CaSO₄·2H₂O + 19H₂O → 3CaO·Al₂O₃·3CaSO₄·32H₂O (AFt). This reaction reaches its peak 1-3 hours after water addition. The generated AFt consists of needle-like or columnar crystals that rapidly interlock within the gaps between cement particles, forming a preliminary microstructure—the core structural support for the cement paste to gain strength in its early stages, within 3 days. Furthermore, during C₄AF hydration, Fe… 3+ It will partially replace Al in AFt3+ The formation of Fe-containing calcite has a structure similar to AFt, with slightly higher stability. Although the formation rate is slower than that of C3A, it can continuously replenish AFt crystals and extend the framework strengthening period. At the same time, the hydration exothermic rate of C4AF is lower than that of C3A, which can alleviate the local temperature rise caused by the concentrated exothermic reaction of C3A, avoid the formation of pores due to excessively rapid evaporation of water, and indirectly ensure the compactness of the early strength structure. The essence of early strength is the transformation of cement paste from loose particles to dense solids. Ferrous phase products accelerate this process in the following ways: the needle-like structure of AFt crystals can penetrate deep into the microcracks on the surface of cement particles, or form an interlocking structure with the subsequently generated calcium silicate hydrate, namely CSH gel, and C3S / C2S hydration products; AFt provides an early rigid skeleton, and the viscous CSH gel wraps around the surface of AFt and cement particles, enhancing the interfacial adhesion. This microscopic combination of rigid skeleton and viscous cement allows cement paste to form stable strength in 3 days. For example, the 3-day compressive strength of high ferric phase cement can reach more than 50% of that of 28-day cement, which is much higher than the 40% of ordinary cement. However, in this embodiment, the overall early strength is >5MPa, which is higher than the early strength standard of overall cement.

[0042] Table 2 shows that the early strength measured at 3 days and the later strength measured at 90 days in both Comparative Example 1 and Comparative Example 2 were significantly lower than before, as were the elastic moduli. This indicates that the lack of an activator resulted in cement having almost no early strength and a slow increase in later strength. The core reason is that the main component of potential hydraulic materials, such as slag, is a glassy structure with stable Si-O-Si and Al-O-Al covalent bonds on its surface, making it difficult to react with water at room temperature (i.e., inert). The role of alkaline materials is to break these stable bonds and initiate the hydration reaction. If activation is omitted, problems such as the inability to initiate the hydration reaction and the lack of cementitious products will occur. In an alkaline environment, hydroxide ions (OH-)... - It is a catalyst that disrupts inert structures. During normal activation: OH - It attacks the Si-O-Si bonds on the surface of the slag glass, causing them to break and form active silicon-oxygen tetrahedra SiO4. 4- and aluminum oxide tetrahedron AlO4 5- These active ions then react with Ca... 2+ The combination produces CSH gel and CAH gel—these two products are the core of the cementitious material's strength, tightly encapsulating particles to form a dense spatial network structure, providing high strength. Without alkali activation: OH - With extremely low concentrations, derived only from the weak ionization of water, the Si-O-Si bonds cannot be broken. The slag particles remain in an inert state, only able to undergo minimal surface adsorption with water. There is no CSH or CAH gel formation, no chemical bonding, and no natural cementing ability, so strength is naturally out of the question.

[0043] As shown in Table 2, Comparative Example 3 exhibited low strength in the early stages, but its strength was not significantly affected in the later stages. The core reason for this is that the primary function of the water-reducing agent is to disperse cement particles. Hydrophilic groups in the agent's molecular structure, such as sulfonic acid and carboxyl groups, adsorb onto the surface of the cement particles, forming a negatively charged repulsive layer. This breaks up particle aggregation, prevents flocculation, and allows the cement particles to be uniformly dispersed with less water, thus satisfying the requirements for construction fluidity. The absence of the water-reducing agent directly leads to a decrease in the water-cement ratio (W / B). To achieve fluidity, a higher water-cement ratio, such as 0.5-0.6, is required. Excess water will form numerous capillaries in the hardened body, and the aggregation of cement particles will result in incomplete hydration, preventing internal particles from contacting water. With the addition of the water-reducing agent, the water-cement ratio can be reduced to 0.3-0.4, with just enough water to meet the hydration requirements of the cement, leaving no excess free water. After the cement particles are evenly dispersed, the surface area for the hydration reaction increases, resulting in 20%-30% more CSH gel formation in the early stages compared to the system without water-reducing agents. This gel can rapidly fill micropores, reducing the porosity of the early-hardened body from 45% to below 30%, directly improving compressive / flexural strength; for example, 3-day strength can be increased by 30%-50%. The later-stage strength shows no significant change because the strength of cement is determined by the total amount of CSH gel generated from the complete hydration of C3S and C2S, which is determined by the mineral composition of the cement itself and is unrelated to water-reducing agents. Comparative Example 4 exhibits lower strength throughout the entire process than the other examples, with a slightly larger reduction in early strength. This is because Comparative Example 4 did not add graphene oxide. The surface of graphene oxide nanosheets contains numerous polar functional groups, which can interact with the CaO on the surface of cement particles. 2+ Coordination occurs, forming a localized high concentration of Ca. 2+ The region provides preferential nucleation sites for hydration products such as CSH gel; compared with cement systems without GO, the presence of GO can reduce the nucleation barrier of hydration products, that is, the energy threshold for products to transform from ionic state to solid crystal / gel, and accelerate the hydration rate of minerals such as C3S—the degree of hydration in the early stage (3d, 7d) is improved, more CSH gel is generated, thereby improving the early strength.

[0044] II. Acid and alkali resistance and corrosion resistance test 1. Acid resistance test Testing standards: GB / T 749-2008 "Test Method for Sulfate Attack Resistance of Cement", T / CBMF 37-2018 "Acid-Resistant Cement" Test objective: To evaluate durability in acidic environments, such as industrial wastewater and acid rain. Test method: Prepare 40mm×40mm×160mm specimens, cure them for 28 days, and then immerse them in 5% sulfuric acid solution (pH≈1.0) or 10% hydrochloric acid solution. The control group is immersed in distilled water. The appearance changes of the specimens are measured periodically (7d, 14d, 28d, 90d) to determine whether cracking or peeling occurs, and the compressive strength loss rate is calculated. Temperature (40℃) can be used to accelerate the corrosion and shorten the test cycle.

[0045] 2. Alkali resistance test Test objective: To verify stability in a highly alkaline environment and prevent expansion and cracking caused by the alkali-silicon reaction.

[0046] Test method: The rapid mortar bar method (GB / T 14684-2011) was adopted: mortar bars of 25mm×25mm×280mm were prepared and immersed in 1mol / L NaOH solution at 80℃. The expansion rate was measured at 14d and 28d. The test principle is that the CaO content in high-ferrous phase cement is relatively high, and the alkali content (Na2O equivalent ≤0.6%) needs to be controlled to avoid excessive alkali reacting with active SiO2 in aggregate.

[0047] III. Service Life Assessment (Long-Term Performance Inference) The service life of cement is affected by environmental factors (temperature, humidity, corrosive media), loads, etc., and is difficult to measure directly. It needs to be inferred through accelerated aging tests combined with service life prediction models. 1. Accelerated aging test Thermal aging test: 28-day-old specimens were placed in hot water at 60℃, 80℃, and 100℃ for curing. The strength loss rate and microstructure changes were tested periodically, and the lifespan at room temperature was extrapolated using the Arrhenius equation.

[0048] ; k: Aging reaction rate constant; A: Pre-exponential factor; Ea: Activation energy of the aging reaction; R: Ideal gas constant; T: Absolute temperature of thermal aging; room temperature 25℃. Then, according to the formula... Calculate the lifetime t1 at room temperature.

[0049] 2. Liquidity Test Fill the slump cone with freshly mixed concrete in three layers, each layer about 1 / 3 of the cone's height (approximately 100mm). After each layer is filled, tamp it evenly along the cone wall 25 times with a tamping rod, starting from the edge and moving towards the center to ensure even aggregate distribution. The tamping rod should penetrate the current layer and extend into the next (approximately 5-10mm deep) to avoid hitting the cone wall and bottom slab. After the last layer is filled, use a trowel to level the concrete at the cone opening, cutting off any excess to ensure the top surface is flush with the opening. Immediately after filling, hold the top of the slump cone with both hands and lift it vertically upwards at a uniform speed (lifting time should be controlled within 5-10 seconds to avoid tilting or shaking and prevent concrete deformation). After lifting, the concrete will slump due to its own weight. After the slump stabilizes (approximately 30 seconds), use a steel ruler to measure vertically from the bottom slab surface to the highest point of the slumped concrete; this value is the slump value (unit: mm).

[0050] Table 3. Relevant tests conducted on Examples 1-3 and Comparative Examples 1-5.

[0051] As shown in Table 3, the compressive strength loss rate of Examples 1-3 is less than 9%. Among them, Example 2 has the lowest loss rate under acidic conditions and the lowest expansion rate under alkaline conditions. Correspondingly, it has the longest predicted lifespan. This may be because of the large amount of graphene oxide added. Graphene oxide is a two-dimensional nanosheet structure with a single atomic layer thickness. Its unique sheet-like morphology is the core basis for corrosion resistance. It can be uniformly distributed in cement paste through ultrasonic dispersion or chemical modification. The nanosheets will randomly overlap and intersect inside the cement matrix like leaves, forming a three-dimensional network of nanoscale physical barriers. For liquids, such as acidic solutions, chloride ion solutions, or gases, such as CO2 and SO2, this barrier significantly lengthens the penetration path—the originally linear pore channels are blocked and divided into narrow, tortuous channels by the GO sheets, greatly reducing the penetration rate of the medium, including capillary water absorption and ion diffusion rates. Simultaneously, the density of the GO sheets can directly block the passage of some large molecular corrosive substances, such as certain corrosive salts, reducing their contact with cement hydration products. The corrosion of cement-based materials is essentially caused by the corrosive medium entering the matrix through internal pores and triggering a reaction. GO can optimize the matrix pore structure by regulating the cement hydration process. The interfacial transition zone of cement-based materials, such as the interface between cement paste and aggregate, is a structurally weak point—this area has many pores and loosely arranged hydration products, easily becoming a breakthrough point for corrosive media, and cracks often originate from the interfacial zone. GO can enhance corrosion resistance by strengthening the interfacial region. GO nanosheets can bridge the interface between cement paste and aggregate. The oxygen-containing functional groups on its surface can chemically bond with the hydroxyl groups on the surface of aggregates such as quartz sand, such as through hydrogen bonds and covalent bonds, while also tightly binding with CSH gel, eliminating voids and defects in the interfacial region. When the matrix is ​​subjected to external forces or erosion and expansion, the GO sheets can absorb energy through the pull-out effect, inhibiting the initiation and propagation of interfacial microcracks—preventing cracks from becoming channels for rapid penetration of corrosive media, thereby slowing down the corrosion process. The comparative examples also show that Comparative Examples 1-2, which did not use alkaline activators, showed a slight decrease in corrosion resistance. Comparative Example 3, which did not use water-reducing agents, had no impact on corrosion resistance as its core function is to improve workability. However, Comparative Example 4, which did not add graphene oxide, undoubtedly showed a significant decrease in corrosion resistance.

[0052] As shown in Table 3, in the examples, Example 2 had the highest slump, and among the comparative examples, only Comparative Example 4, except for Comparative Example 5, had a significantly reduced slump. This is because the water-reducing agent plays an indispensable role in the fluidity of cement. Its core mechanism is to break the agglomeration of cement particles and release the encapsulated free water through three key functions: physical adsorption, charge repulsion, and steric hindrance. At the same time, it optimizes the internal structure of the paste. When cement comes into contact with water, its main mineral components, such as tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A), will undergo rapid hydration reactions to generate positively charged hydration products, such as calcium hydroxide (Ca(OH)2) and the initial particles of hydrated calcium silicate (CSH) gel. These positive charges will attract water molecules and cement particles to aggregate with each other. The polycarboxylate superplasticizer molecules have an amphiphilic structure, with a hydrophilic group at one end, such as a carboxyl group (-COOH) or a sulfonic acid group (-SO3H), and a hydrophobic group at the other end, such as a long carbon chain or a benzene ring. When water-reducing agents are added, their hydrophobic groups preferentially adsorb onto the surface of cement particles or hydration products. This is because the polarity of the cement particle surface has a stronger affinity for the hydrophobic groups, while the hydrophilic groups face the solution side, forming a stable structure where the water-reducing agent molecules encapsulate the cement particles. This step is fundamental to all other effects—only with the directional adsorption of the water-reducing agent can subsequent repulsive and steric hindrance effects occur. After adsorption, the hydrophilic groups of the water-reducing agent form a negatively charged adsorption layer on the surface of the cement particles. Simultaneously, positive ions in the solution, such as Na+, are also adsorbed. + Ca 2+ The adsorption layer is attracted by the negative charge, forming a diffusion layer on the outside of the adsorption layer. The adsorption layer and the diffusion layer together constitute the double electric layer. According to the colloidal stability theory, without the addition of water-reducing agent, the van der Waals attraction of the positive charge on the surface of cement particles dominates, causing the particles to attract each other and aggregate, forming a flocculent structure. A large amount of free water is trapped inside the flocs and cannot participate in the flow. After the addition of water-reducing agent, the repulsive force of the negative charge in the double electric layer is greatly enhanced: the negative charges on the surfaces of adjacent cement particles repel each other, canceling the van der Waals attraction, breaking up the originally aggregated flocculent structure, and releasing the water trapped inside the flocs, which becomes effective water that can flow freely. The macroscopic manifestation is that the fluidity of the cement paste is significantly improved, manifested as an increase in slump, or the amount of water can be reduced and the water-cement ratio can be lowered while the fluidity remains unchanged. In addition, the hydrophilic groups of polycarboxylate-based water-reducing agents are long-chain polymers such as polyoxyethylene ether side chains. These long side chains extend from the surface of cement particles into the aqueous phase, forming a three-dimensional polymer adsorption film. When adjacent cement particles approach each other, their extended side chains collide and compress, generating a physical spatial resistance force—this force is independent of electric charge, even as the double layer is gradually consumed by hydration reactions, such as Ca. 2+ Increased concentration leads to a thinning of the electric double layer, but steric hindrance still prevents particles from re-aggregating.

[0053] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing high-strength cement clinker with high ferrous phase, characterized in that, Includes the following steps: S1. Waste Activation At room temperature, white mud, waste desulfurizing agent, fine steel slag powder, and blast furnace slag are dissolved and mixed in ethylene glycol and then placed in a microwave reactor. The mixture is treated with microwave radiation power of 100-220W and microwave frequency of 700-2000MHz for 20-30 minutes. After cooling, calcium oxide and ethylene glycol are added, the temperature is raised to 50-75℃, fly ash is added, and the active material and fly ash are ground to 250-340 mesh. The activated waste material is then obtained by soaking in ethylene glycol, heating, cooling, and drying. S2. Modified activator Slag, tetrahydrofuran, and triethylamine were placed in an Erlenmeyer flask and fixed on a magnetic stirrer. The stirrer was turned on and the speed was adjusted to a moderate level. Acryloyl chloride was slowly added dropwise to the Erlenmeyer flask containing slag through a constant pressure dropping funnel. The dropping rate was controlled so that the dropping process was completed within 15-20 minutes. During the dropping process, the temperature change of the reaction system was carefully observed. If the temperature rose too quickly, the dropping was stopped and continued after the temperature stabilized. After the dropping was completed, the reaction was stirred for 2-3 hours. An appropriate amount of anhydrous sodium sulfate was added to the clear liquid after the reaction was transferred, and the mixture was stirred for 15-20 minutes. The mixture was then filtered to remove anhydrous sodium sulfate and impurities such as water that it had adsorbed. The filtrate was then evaporated by rotary evaporation at 40-50℃ and dried under vacuum for 12 hours to obtain the modified activator. S3. Copolymerization reaction The modified activator obtained from S2, ethylene glycol monovinyl polyethylene glycol ether, 2-acrylamide-2-methylpropanesulfonic acid, itaconic acid, and an appropriate amount of deionized water were placed into a 250 mL reactor equipped with a stirrer. The reactor was stirred at 60 °C and 60 r / min until the ethylene glycol monovinyl polyethylene glycol ether was completely dissolved. At this point, a 30% (w / w) H2O2 solution was added, and stirring was continued for 15 min. Simultaneously, acrylic acid was added dropwise at a uniform rate for 1 h. After the addition, stirring was continued, and the reactor was kept at 60 °C for 3 h. Then, a 30% (w / w) NaOH aqueous solution was added to adjust the pH to 6-7, resulting in the waste residue of the grafted water-reducing agent. S4. Preparation of high-strength cement clinker with high ferrophase S401. Preparation of graphene oxide Graphite powder and NaNO3 powder were added to a 1000 mL round-bottom flask. Then, 100 mL of concentrated H2SO4 was slowly added under ice bath conditions. After 4 hours, KMnO4 was slowly added and stirred until completely dissolved in the flask. The sample was then immersed in an ice bath for 20 minutes. The flask was then removed from the ice bath and stirred continuously at room temperature for 24 hours. The resulting mixture was then mixed with 200 mL of deionized water and stirred at 0°C for 20 minutes to form a dispersion. 10 mL of H2O2 was then slowly added using a pipette to dissolve the dispersion. The resulting dispersion was filtered through a Buchner funnel, and 20 mL of hydrochloric acid solution was transferred to the flask with the SO42-. 2- The reaction was carried out, and then the solution was continuously stirred with ultrapure water for 4 days to remove some metal ions and residual acidic substances. Finally, the prepared graphene oxide solution was purified by centrifugation four times and vacuum filtration was repeated until the pH reached neutral to obtain graphene oxide. S402. Mixing Gypsum, limestone, and waste residue from grafted water-reducing agent obtained from S3 were added to a planetary ball mill and dry-mixed at 200 r / min for 30 min. The mixture was then transferred to a twin-shaft mixer, where graphene oxide obtained from S401 was slowly added while stirring. Deionized water was added, and stirring was continued for 45-60 min. The mixed material was then loaded into a mold and pressed into cylindrical test blocks under a pressure of 20-30 MPa. The blocks were left to stand at room temperature for 24 h. After demolding, the test blocks were placed in a muffle furnace and heated to 200℃ at a rate of 5℃ / min. The temperature was held for 1 h, and then increased to 1300-1400℃ at a rate of 10℃ / min. The temperature was held for 2-3 h, and the blocks were allowed to cool naturally to room temperature. The blocks were then crushed and ground in a ball mill to a specific surface area of ​​350-450 m² / kg to obtain high-iron phase high-strength cement clinker.

2. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The steel slag powder and blast furnace slag used are white powders with a specific surface area of ​​350 m². 2 / kg, 28d activity index greater than 105%, mass coefficient K = 2.07 > 1.2, alkalinity coefficient B = 1.14 > 1, belonging to alkaline slag.

3. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The raw materials used in S1 are: 45-55 parts steel slag fine powder, 45-55 parts blast furnace slag, 5-8 parts fly ash, and 1-2 parts calcium oxide.

4. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The white mud is one of papermaking white mud and alkali production white mud. The waste desulfurizing agent is a deactivated solid calcium-based desulfurizing agent, which comes from the dry desulfurization process and is in powder, columnar and clover-shaped form. The waste desulfurizing agent contains 5-15% Ca(OH)2, 10-25% CaSO3 and 60-75% CaSO4.

5. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The mass fraction of the raw materials used in S2 is 15-45 parts of inorganic activating component and organic activating component.

6. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The molar ratio of the raw materials used in S3 is as follows: the modified activator obtained in S2: ethylene glycol monovinyl polyethylene glycol ether: 2-acrylamide-2-methylpropanesulfonic acid: itaconic acid: acrylic acid = 1: 3.5-4.0: 0.8-1.2: 0.9-1.1: 1.2-1.3, wherein the molecular weight of ethylene glycol monovinyl polyethylene glycol ether is 600.

7. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The raw materials used in the preparation of the modified graphene in S401 are: 2-3 parts graphite powder, 3-4 parts NaNO3, and 6-7 parts KMnO4.

8. The method for preparing high-strength cement clinker with high ferrophase according to claim 1, characterized in that, The amount of water added in S402 needs to be controlled so that the moisture content of the system is 12%-15%.

9. A high-strength cement clinker with a high iron phase prepared by the preparation method according to any one of claims 1-8, characterized in that, The prepared cement clinker has a high solid waste utilization rate, an early compressive strength >55MPa, and a seawater corrosion attenuation rate of <10% after 180 days, making it suitable for the preparation of high-strength cement in various scenarios.

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