Steel slag-based mineral admixture and preparation and application methods thereof
By leveraging the synergistic acid etching and grinding aid effects of steel slag-based mineral admixtures, combined with multi-component adsorption groups and coordinated activated iron phases, the activation problem of the inert RO phase of steel slag was solved, achieving efficient and environmentally friendly grinding and hydration reactions, and enhancing the activity and strength of steel slag in concrete.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies are difficult to effectively activate the inert RO phase in steel slag, resulting in low activity when applied to concrete, high grinding energy consumption, poor economic efficiency, and common activation methods have environmental risks or limited efficiency.
A steel slag-based mineral admixture is used to pre-activate inert components through synergistic acid etching and efficient grinding aid effects, and to improve grinding efficiency and hydration reaction activity through multi-component adsorption groups and specific coordination activation of the iron phase.
It significantly reduces grinding energy consumption, improves grinding fineness, increases specific surface area, promotes RO phase hydration, enhances the activity and long-term strength of steel slag in concrete, and achieves efficient and environmentally friendly utilization of steel slag.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete technology, and in particular to a steel slag-based mineral admixture and its preparation and application method. Background Technology
[0002] The steel industry generates over 100 million tons of steel slag annually. Its stockpiling and landfilling not only occupy land but also pose environmental risks. Grinding it into steel slag-based mineral admixtures is an important way to replace some cement and reduce the carbon footprint of concrete. However, due to its complex mineral composition and high formation temperature, steel slag has inherent defects when used as an admixture, severely restricting its high-value-added and large-scale utilization. The core problem lies in the high chemical inertness and extremely low cementitious activity of the RO phase (mainly FeO-MgO-MnO solid solution), which accounts for 20%-40% of its mass. Studies have confirmed (for example, Wang et al.'s systematic analysis of the cementitious properties of steel slag powder in "Hydration properties and microstructure of steel slag-cement binder" (Construction and Building Materials, 2018, 162: 669-678) pointed out that its 28-day activity index is low), which is mainly attributed to: 1) the inert RO phase is difficult to hydrate: its dense crystal structure hardly undergoes hydration reaction under normal alkaline conditions, and it mainly exists in the form of "inert filler", which has a weak contribution to strength; 2) high grinding energy consumption and low efficiency: hard phases such as RO phase cause grinding energy consumption to be significantly higher than other admixtures, and it is easy to generate agglomeration, which creates a bottleneck in fineness improvement.
[0003] To address the issues of low activity and difficulty in utilizing steel slag, existing technologies mainly focus on modification through physical, chemical, and compound methods, but all have significant limitations: First, deep physical grinding and ultrafine fractionation techniques. This method aims to increase the reaction interface by greatly increasing the specific surface area. However, this leads to a significant increase in grinding power consumption, poor economic efficiency, and limited intrinsic activity activation of the RO phase. Second, single activation technologies such as high-temperature reconstruction or chemical activation. High-temperature reconstruction has extremely high energy consumption and carbon emissions, negating the environmental benefits of solid waste utilization. Commonly used chemical activation methods, such as simply using sulfate or strong alkali activation, can improve early strength to some extent, but have serious drawbacks. Studies have shown (e.g., Li et al.'s study on the long-term performance of steel slag activated by high-concentration alkali, "Long-term properties of steel slag activated by high-concentration alkali: Strength, shrinkage and microstructure" (Cement and Concrete Composites, 2020, 114: ...) 103741), which can easily lead to a decline in concrete strength and durability risks in the later stages. At the same time, this type of method has poor targeting of the RO phase and limited efficiency. Thirdly, the simple compounding technology with high-activity admixtures. In order to meet the activity index requirements, the industry generally adopts the method of compounding steel slag powder with a large amount of high-quality slag powder or fly ash. This is actually using high-value solid waste to "dilute" low-value solid waste, and does not really improve the cementitious value of steel slag itself. Under the current situation of increasingly scarce high-quality slag resources, this technical path is unsustainable. In addition, decomposing the RO phase requires changing the steelmaking process (such as the method disclosed by patent CN111606583A to directly decompose the RO phase through a carbon reduction bed), which is difficult to achieve for most steel slags; or simply improving grinding efficiency by adding grinding aids, but these methods have not systematically solved the inertia problem of the RO phase under conventional cement hydration conditions. Another literature (such as Zhang et al.'s review on activation methods of steel slag: Reactivity, performance and mechanism) (2022, 45: 103557) also points out that developing multifunctional additives that can specifically recognize and activate iron-based inert phases is the main challenge and breakthrough direction of current technology.
[0004] In summary, existing technologies either have high economic and environmental costs (such as ultrafine grinding and high-temperature remodeling), pose performance and durability risks (such as strong alkali activation), or fail to address the core challenge of activating the inert RO phase (such as simple compounding or single-function additives). Therefore, developing a novel, highly efficient admixture that can synergistically enhance performance during the grinding stage, directionally activate the inert phase during application, and has broad environmental adaptability has become an urgent technological need to overcome the performance bottleneck of steel slag-based mineral admixtures and truly realize their large-scale, high-value utilization. Summary of the Invention
[0005] In order to solve the technical problems existing in the prior art, the purpose of this invention is to provide a steel slag-based mineral admixture and its preparation and application method to solve the above-mentioned technical problems.
[0006] The steel slag-based mineral admixture provided by this invention has multiple functions: synergistic acid etching and efficient grinding aid effects, improving grinding efficiency and pre-activating inert components; synergistic effect of multiple adsorption groups, combining dispersibility and highly adaptable water reduction effect; specific coordination activation of the iron phase, solving the problem of RO phase hydration inertness.
[0007] According to a first aspect of the present invention, the present invention provides a method for preparing a steel slag-based mineral admixture, comprising the following steps: In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and dropwise pipeline, polyether monomers and deionized water are mixed, and an initiator is added to obtain a bottom liquid. Under stirring, a mixed solution of alkanolamine monomers and five-membered ring monomers, a mixed solution of carboxyl monomers and sulfonic acid monomers, a mixed solution of chain transfer agent and reducing agent, and a mixed solution of phosphate monomers and acid anhydrides are added dropwise to the bottom liquid for a dropwise reaction. After the dropwise reaction is completed, a heat preservation and aging treatment is performed to obtain an aged mixture, which is then acidified to obtain the steel slag-based mineral admixture additive.
[0008] In some embodiments, mixing the polyether monomer and deionized water includes: adding the polyether monomer and water into a reaction vessel, turning on the stirrer, and heating to 60-65°C for mixing.
[0009] In some embodiments, the initiator is added 2 minutes before the start of the dropping reaction.
[0010] In some embodiments, the polyether monomer is at least one of allyl polyoxyethylene ether and methyl allyl polyoxyethylene ether; the mass ratio of the polyether monomer to water is 350~380:250; the initiator is at least one of ammonium persulfate, potassium persulfate and sodium persulfate; the mass ratio of the initiator to water is 1.2-1.8:250.
[0011] In some embodiments, the molecular weight of both the allyl polyoxyethylene ether and the methyl allyl polyoxyethylene ether is 2400.
[0012] In some embodiments, the mixed solution of the alkanolamine monomer and the five-membered ring monomer is a mixture of the alkanolamine monomer, the five-membered ring monomer, and water; the alkanolamine monomer is at least one selected from N-(2-hydroxyethyl)acrylamide, N-(2-hydroxypropyl)methacrylamide, N,N-bis(2-hydroxyethyl)-2-acrylamide, and N,N-bis(2-hydroxyethyl)-2-methylacrylamide; the five-membered ring monomer is N-vinylpyrrolidone; in the mixed solution of the alkanolamine monomer and the five-membered ring monomer, the mass ratio of the alkanolamine monomer to water is 18-22:40, the mass ratio of the five-membered ring monomer to water is 36-40:40, and the mass ratio of the alkanolamine monomer to the polyether monomer is 18-22:350-380.
[0013] In some embodiments, the mixed solution of carboxyl monomer and sulfonic acid monomer is a mixture obtained by mixing carboxyl monomer, sulfonic acid monomer and water, and adjusting the pH to 5.5-6.5; the carboxyl monomer is at least one of acrylic acid and methacrylic acid; the sulfonic acid monomer is at least one of 2-acrylamido-2-methylpropanesulfonic acid and sodium propylene sulfonate; in the mixed solution of carboxyl monomer and sulfonic acid monomer, the mass ratio of carboxyl monomer to water is 23-27:45, the mass ratio of sulfonic acid monomer to water is 6-10:45; and the mass ratio of carboxyl monomer to polyether monomer is 23-27:350-380.
[0014] In some embodiments, the method for preparing the mixed solution of the carboxyl monomer and the sulfonic acid monomer includes the following steps: Dissolve 23-27 parts by weight of carboxyl monomer and 6-10 parts by weight of sulfonic acid monomer in 45 parts by weight of water to obtain a mixed solution. Cool the solution to 0°C and adjust the pH of the mixed solution to 5.5-6.5 with 38-42 parts by weight of 30wt% sodium hydroxide solution to obtain the mixed solution of carboxyl monomer and sulfonic acid monomer.
[0015] In some embodiments, the mixed solution of the chain transfer agent and the reducing agent is a mixture of the chain transfer agent, the reducing agent and water; the chain transfer agent is at least one of mercaptoethanol and mercaptopropanol; the reducing agent is vitamin C; in the mixed solution of the chain transfer agent and the reducing agent, the mass ratio of the chain transfer agent to water is 0.8-1.2:40, and the mass ratio of the reducing agent to water is 0.4-0.6:40.
[0016] In some embodiments, the mixed solution of the phosphate monomer and the acid anhydride is a mixture of the phosphate monomer, the acid anhydride, and water; the phosphate monomer is at least one of hydroxyethyl acrylate phosphate and hydroxyethyl methacrylate phosphate; the acid anhydride is at least one of maleic anhydride and itaconic anhydride; in the mixed solution of the phosphate monomer and the acid anhydride, the mass ratio of the phosphate monomer to water is 8-12:50, the mass ratio of the acid anhydride to water is 24-26:50; and the mass ratio of the phosphate monomer to the polyether monomer is 8-12:350-380.
[0017] In some embodiments, the temperature of the dropwise addition reaction is 60-80°C; the dropwise addition time range of the mixed solution of the alkanolamine monomer and the five-membered ring monomer is 0-1.5 h; the dropwise addition time range of the mixed solution of the carboxyl monomer and the sulfonic acid monomer is 0-3 h; the dropwise addition time range of the mixed solution of the chain transfer agent and the reducing agent is 0-3 h; and the dropwise addition time range of the mixed solution of the phosphate monomer and the acid anhydride is 2-3 h.
[0018] In some embodiments, during the dropwise addition reaction, the starting time of the dropwise addition of the mixed solution of the alkanolamine monomer and the five-membered ring monomer is marked as 0h; the dropwise addition time interval of the mixed solution of the alkanolamine monomer and the five-membered ring monomer is 0-1.5h (i.e., dropwise addition is carried out from the beginning of the dropwise addition reaction to 1.5h); the dropwise addition time interval of the mixed solution of the carboxyl monomer and the sulfonic acid monomer is 0-3h (i.e., dropwise addition is carried out from the beginning of the dropwise addition reaction to 3h, but the temperature needs to be controlled and stabilized at 60-80°C during this process); the dropwise addition time interval of the mixed solution of the chain transfer agent and the reducing agent is 0-3h (i.e., dropwise addition is carried out from the beginning of the dropwise addition reaction to 3h); and the dropwise addition time interval of the mixed solution of the phosphate monomer and the acid anhydride is 2-3h (i.e., dropwise addition is carried out from 2h to 3h of the dropwise addition reaction).
[0019] In some embodiments, the temperature of the heat preservation and curing treatment is 60~80℃, and the heat preservation and curing treatment time is 1-2 hours; In some embodiments, the acidification includes: adding an acidic solution to the aged mixture to obtain an acidified mixture; In some embodiments, the acidic solution is a sulfuric acid solution or a hydrochloric acid solution; the mass percentage concentration of the acidic solution is 10-30 wt%.
[0020] In some implementations, the mass percentage concentration of the acidic solution is 20 wt%.
[0021] In some embodiments, the solid content in the acidified mixture is 50%.
[0022] According to a second aspect of the present invention, the present invention provides a steel slag-based mineral admixture additive prepared by the above-described preparation method.
[0023] According to a third aspect of the present invention, the present invention provides the application of the above-mentioned steel slag-based mineral admixture additive in enhancing the activity of steel slag-based mineral admixtures.
[0024] In some embodiments, the application of the steel slag-based mineral admixture additive in enhancing the activity of the steel slag-based mineral admixture includes the following steps: (1) Steel slag pretreatment: Take steel slag with f-CaO content of less than 4%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is ≤10mm. (2) Preparation of steel slag powder: The crushed steel slag described in step (1) is ground (for 8-10 minutes), and then the steel slag-based mineral admixture is added by spraying while it is being ground. Then, the grinding continues for 40-50 minutes to obtain steel slag with enhanced activity.
[0025] In some embodiments, the solid content of the steel slag-based mineral admixture in step (2) is 20 wt%, and the mass of the steel slag-based mineral admixture is 2.0-3.0 wt% of the mass of the crushed steel slag.
[0026] In some embodiments, the time for adding the steel slag-based mineral admixture by spraying in step (2) is 3-5 minutes.
[0027] In some embodiments, the steel slag with enhanced activity described in step (2) can be used in the preparation of cement, mortar or concrete.
[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The steel slag-based mineral admixture additive provided by this invention has synergistic acid etching and efficient grinding aid effects, which can improve grinding efficiency and pre-activate inert components. In the grinding pretreatment stage, the additive of this invention plays a dual activation function. On the one hand, the free hydrogen ions released by it can effectively acid etch the steel slag particles, especially destroying the chemically stable and low-reactivity inert RO phase (mainly FeO-MgO-MnO solid solution), forming micropores and cracks on its dense surface, thereby weakening the integrity of the mineral crystal structure and creating more easily broken initial conditions for mechanical grinding. On the other hand, the alkanolamine groups introduced into the additive molecule can be adsorbed on the surface of steel slag particles and grinding media during the grinding process, and play an efficient grinding aid function by reducing surface energy, preventing particle agglomeration, and promoting crack propagation. The synergistic effect of these two factors has achieved a significant reduction in grinding energy consumption, an effective improvement in grinding fineness, and created a larger specific surface area and more active sites for subsequent hydration reactions, realizing the "mechanical-chemical" synergistic activation of steel slag.
[0029] (2) The steel slag-based mineral admixture provided by this invention has a synergistic effect of multiple adsorption groups, combining dispersibility and high adaptability to reduce water content. When applied to the mixing of cementitious materials with water, the admixture of this invention exhibits excellent interface regulation capabilities. Its molecular structure contains carefully designed carboxylate groups (-COO-). - ), sulfonate (-SO3) - ), phosphate (-PO²⁻ / HPO₄) - It contains a variety of highly polar adsorption groups, forming a multi-element, high-efficiency adsorption system. These groups can be rapidly adsorbed onto the surface of cement, slag powder, fly ash, and pretreated steel slag particles through various mechanisms such as electrostatic interaction and complexation, forming a stable double layer of protection of steric hindrance and electrostatic repulsion. This efficiently disperses various adhesive particles, ensuring that they can stably and persistently exert their high water-reducing effect in different adhesive systems and different phases.
[0030] (3) The steel slag-based mineral admixture additive provided by this invention can specifically coordinate and activate the iron phase, solving the problem of RO phase hydration inertness. Due to its dense crystal structure and low surface activity, the RO phase is difficult to participate in the reaction in the conventional cement hydration environment, which is a key factor restricting the improvement of the cementitious activity and utilization rate of steel slag admixtures. In the admixture of this invention, a functional group with a unique five-membered ring chelate structure is innovatively introduced. This structure can react with the iron (Fe) released in the RO phase. 2+ / Fe 3+Metal ions such as iron slag form stable and efficient coordination complexes. This coordination not only disrupts the passivation layer on the surface of RO phase mineral particles, making it easier for internal metal ions to dissolve and participate in the hydration reaction network, but also forms soluble activation intermediates in the liquid phase, promoting the formation and precipitation of gelling hydration products (such as iron-containing CSH gel and calcium aluminoferrite phase). This mechanism promotes the transformation of some RO phases from "inert filler" to "active gelling component," increasing the overall secondary hydration reaction degree and long-term strength contribution of steel slag, making it possible to use steel slag in concrete with large dosages and high performance. Detailed Implementation
[0031] To better understand the technical solution of this invention, the embodiments of this invention are described in detail below. It should be understood that the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0032] The methods for testing the steel slag-based mineral admixtures obtained in the following examples and comparative examples are described below.
[0033] The performance testing and requirements for steel slag-based mineral admixtures are based on GB / T 20491-2017 "Steel Slag Powder for Cement and Concrete". Specific testing methods for fluidity ratio and activity index are given in GB / T 51003, specific surface area is determined according to GB / T 8074, and stability is determined according to the boiling method in GB / T 1346. The workability and mechanical properties testing methods for steel slag-based mineral admixtures in concrete are given in GB / T 50080 and GB / T 50081, respectively. The mass mix ratio for concrete tests is m(cement):m(steel slag-based mineral admixture):m(mineral powder):m(fly ash):m(sand):m(aggregate):m(water) = 180:90:50:50:790:1040:165. The cement used in the tests is Conch Cement P.O42.5R or Golden Sheep Cement P.O42.5R.
[0034] Example 1 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 380 g of allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 65°C for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 minutes before the start of dropping, add 1.2 g of sodium persulfate. Preparation of A-2 drop solution: Y1 is: 18 g of N-(2-hydroxyethyl)acrylamide and 36 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N-(2-hydroxyethyl)acrylamide and N-vinylpyrrolidone, which is labeled as Y1; Y2 is: 27 g of methacrylic acid and 6 g of sodium propylene sulfonate are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0°C, and the pH of the mixed solution is adjusted to 5.6 with 38 g of 30wt% sodium hydroxide solution to obtain a mixed solution of methacrylic acid and sodium propylene sulfonate, labeled as Y2. Y3 is: 1.2 g of mercaptopropanol and 0.6 g of vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptopropanol and vitamin C is obtained, labeled as Y3; Y4 is: 12 g of hydroxyethyl methacrylate phosphoric acid and 25 g of itaconic anhydride are dissolved in 50 g of water, mixed well, and a mixed solution of hydroxyethyl methacrylate phosphoric acid and itaconic anhydride is obtained, which is labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time range of Y1 is 0~1.5 h, while the dropping time range of Y2 and Y3 is 0~3 h, and the dropping time range of Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 80℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 80℃ for 1 hour to obtain the matured mixture; A-5 Post-treatment: Add 43 g of 20wt% sulfuric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0035] The application of the steel slag-based mineral admixture additive obtained in Example 1 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.9%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 10 min (using a ball mill with an operating power of 5.5 kW, manufactured by Jiangxi Chuanqi Mineral Processing Equipment Manufacturing Co., Ltd., model MQ0406; the same below). Then, during the continuous grinding process, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 5 min, and the amount of the steel slag-based mineral admixture with a solid content of 20% is 3wt% of the mass of the crushed steel slag. Grinding continues for 40 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0036] Example 2 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 350 g of methyl allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 70℃ for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 min before the dropwise addition begins, add 1.8 g of potassium persulfate. Preparation of A-2 drop solution: Y1 is: 22 g of N-(2-hydroxypropyl)methacrylamide and 40 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N-(2-hydroxypropyl)methacrylamide and N-vinylpyrrolidone, labeled as Y1; Y2 is: 23 g of acrylic acid and 8 g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0℃, and its pH is adjusted to 5.8 with 42 g of 30wt% sodium hydroxide solution to obtain a mixed solution of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, labeled as Y2. Y3 is: 0.8 g mercaptoethanol and 0.4 g vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptoethanol and vitamin C is obtained, labeled as Y3; Y4 is: 8 g of hydroxyethyl acrylate phosphate and 25 g of maleic anhydride are dissolved in 50 g of water and mixed well to obtain a mixed solution of hydroxyethyl acrylate phosphate and maleic anhydride, labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time interval for Y1 is 0~1.5 h, the dropping time interval for Y2 and Y3 is 0~3 h, and the dropping time interval for Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 70℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 70℃ for 2 hours to obtain the matured mixture; A-5 Post-treatment: Add 39 g of 20wt% hydrochloric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0037] The application of the steel slag-based mineral admixture additive obtained in Example 2 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.5%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 8 min. Then, while grinding continuously, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 3 min, and the amount of the steel slag-based mineral admixture with a solid content of 20% is 3wt% of the mass of the crushed steel slag. Grinding continues for 50 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0038] Example 3 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 365 g of methyl allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 60℃ for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 min before the start of dropping, add 1.5 g of ammonium persulfate. Preparation of A-2 drop solution: Y1 is: 20 g of N,N-bis(2-hydroxyethyl)-2-acrylamide and 38 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N,N-bis(2-hydroxyethyl)-2-acrylamide and N-vinylpyrrolidone, which is labeled as Y1; Y2 is: 25 g of acrylic acid and 10 g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0℃, and the pH of the mixed solution is adjusted to 5.8 with 40 g of 30wt% sodium hydroxide solution to obtain a mixed solution of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, labeled as Y2. Y3 is: 1.0 g mercaptoethanol and 0.5 g vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptoethanol and vitamin C is obtained, labeled as Y3; Y4 is: 10 g of hydroxyethyl acrylate phosphate and 25 g of maleic anhydride are dissolved in 50 g of water and mixed well to obtain a mixed solution of hydroxyethyl acrylate phosphate and maleic anhydride, which is labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time interval for Y1 is 0~1.5 h, the dropping time interval for Y2 and Y3 is 0~3 h, and the dropping time interval for Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 60℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 60℃ for 2 hours to obtain the matured mixture; A-5 Post-treatment: Add 40 g of 20wt% hydrochloric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0039] The application of the steel slag-based mineral admixture additive obtained in Example 3 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.6%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 8 min. Then, while grinding continuously, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 3 min, and the amount of steel slag-based mineral admixture with a solid content of 20% is 2wt% of the mass of the crushed steel slag. Grinding continues for 45 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0040] Example 4 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 365 g of methyl allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 70°C for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 min before the start of dropping, add 1.5 g of ammonium persulfate. Preparation of A-2 drop solution: Y1 is: 20 g of N,N-bis(2-hydroxyethyl)-2-methylacrylamide and 38 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N,N-bis(2-hydroxyethyl)-2-methylacrylamide and N-vinylpyrrolidone, which is labeled as Y1; Y2 is: 25 g of acrylic acid and 10 g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0℃, and the pH of the mixed solution is adjusted to 5.8 with 40 g of 30wt% sodium hydroxide solution to obtain a mixed solution of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, labeled as Y2. Y3 is: 1.0 g mercaptoethanol and 0.5 g vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptoethanol and vitamin C is obtained, labeled as Y3; Y4 is: 10 g of hydroxyethyl acrylate phosphate and 25 g of maleic anhydride are dissolved in 50 g of water and mixed well to obtain a mixed solution of hydroxyethyl acrylate phosphate and maleic anhydride, which is labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time interval for Y1 is 0~1.5 h, the dropping time interval for Y2 and Y3 is 0~3 h, and the dropping time interval for Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 70℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 70℃ for 2 hours to obtain the matured mixture; A-5 Post-treatment: Add 40 g of 20wt% hydrochloric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0041] The application of the steel slag-based mineral admixture additive obtained in Example 4 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.6%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 8 min. Then, while grinding continuously, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 5 min, and the amount of steel slag-based mineral admixture with a solid content of 20% added is 2.5wt% of the mass of the crushed steel slag. Grinding continues for 45 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0042] Example 5 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 365 g of methyl allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 70°C for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 min before the start of dropping, add 1.5 g of ammonium persulfate. Preparation of A-2 drop solution: Y1 is: 20 g of N-(2-hydroxyethyl)acrylamide and 38 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N-(2-hydroxyethyl)acrylamide and N-vinylpyrrolidone, which is labeled as Y1; Y2 is: 25 g of acrylic acid and 10 g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0℃, and the pH of the mixed solution is adjusted to 5.8 with 40 g of 30wt% sodium hydroxide solution to obtain a mixed solution of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, labeled as Y2. Y3 is: 1.0 g mercaptoethanol and 0.5 g vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptoethanol and vitamin C is obtained, labeled as Y3; Y4 is: 10 g of hydroxyethyl acrylate phosphate and 25 g of maleic anhydride are dissolved in 50 g of water and mixed well to obtain a mixed solution of hydroxyethyl acrylate phosphate and maleic anhydride, which is labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time interval for Y1 is 0~1.5 h, the dropping time interval for Y2 and Y3 is 0~3 h, and the dropping time interval for Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 70℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 70℃ for 2 hours to obtain the matured mixture; A-5 Post-treatment: Add 40 g of 20wt% hydrochloric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0043] The application of the steel slag-based mineral admixture additive obtained in Example 5 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.6%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 8 min. Then, while grinding continuously, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 3 min, and the amount of steel slag-based mineral admixture with a solid content of 20% added is 2.5wt% of the mass of the crushed steel slag. Grinding continues for 45 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0044] Example 6 A method for preparing a steel slag-based mineral admixture includes the following steps: Preparation of A-1 bottom solution: In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and dropping pipe, add 250 g of measured water and 365 g of methyl allyl polyoxyethylene ether (molecular weight 2400). Turn on the stirrer (stirring speed 300 rpm) and heat to 70°C for mixing. Continue stirring until the preparation of the steel slag-based mineral admixture is completed. 2 min before the start of dropping, add 1.5 g of ammonium persulfate. Preparation of A-2 drop solution: Y1 is: 20 g of N-(2-hydroxyethyl)acrylamide and 40 g of N-vinylpyrrolidone are dissolved in 40 g of water and mixed to obtain a mixed solution of N-(2-hydroxyethyl)acrylamide and N-vinylpyrrolidone, which is labeled as Y1; Y2 is: 25 g of acrylic acid and 10 g of 2-acrylamido-2-methylpropanesulfonic acid are dissolved in 45 g of water, mixed well to obtain a mixed solution, cooled to 0℃, and the pH of the mixed solution is adjusted to 5.8 with 40 g of 30wt% sodium hydroxide solution to obtain a mixed solution of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, labeled as Y2. Y3 is: 1.0 g mercaptoethanol and 0.5 g vitamin C are dissolved in 40 g of water, mixed well, and a mixed solution of mercaptoethanol and vitamin C is obtained, labeled as Y3; Y4 is: 10 g of hydroxyethyl acrylate phosphate and 25 g of maleic anhydride are dissolved in 50 g of water and mixed well to obtain a mixed solution of hydroxyethyl acrylate phosphate and maleic anhydride, which is labeled as Y4. A-3 Dropping Reaction: The moment when Y1 is first added is marked as 0 h; the dropping time interval for Y1 is 0~1.5 h, the dropping time interval for Y2 and Y3 is 0~3 h, and the dropping time interval for Y4 is 2~3 h; the temperature inside the four-necked flask is maintained at 70℃ during the dropping of Y1, Y2, Y3 and Y4. A-4 Incubation and maturation: After the addition is complete, incubate at 70℃ for 2 hours to obtain the matured mixture; A-5 Post-treatment: Add 43 g of 20wt% hydrochloric acid solution to acidify the matured mixture to obtain the steel slag-based mineral admixture additive.
[0045] The application of the steel slag-based mineral admixture additive obtained in Example 6 in the preparation of steel slag micro powder (enhancing the activity of the steel slag-based mineral admixture) includes the following steps: B-1 Steel slag pretreatment: Take steel slag with f-CaO content of 3.6%, and crush it in two stages by a crusher to obtain crushed steel slag. The particle size of the crushed steel slag is controlled to be ≤10mm. Preparation of B-2 steel slag micro powder: The crushed steel slag is first ground separately for 8 min. Then, while grinding continuously, a steel slag-based mineral admixture with a solid content of 20% is added by spraying (the solid content is adjusted to 20wt% by adding water before use). The spraying time is 3 min, and the amount of steel slag-based mineral admixture with a solid content of 20% added is 2.5wt% of the mass of the crushed steel slag. Grinding continues for 45 min to obtain steel slag micro powder (i.e., steel slag-based mineral admixture).
[0046] Comparative Example 1 Except that no alcohol amine monomer (N-(2-hydroxyethyl)acrylamide) was added to the Y1 drop solution, everything else was the same as in Example 6.
[0047] Comparative Example 2 Except that no five-membered ring monomer (N-vinylpyrrolidone) was added to the Y1 dropping solution, everything else was the same as in Example 6.
[0048] Comparative Example 3 Except that no phosphate monomer (hydroxyethyl acrylate phosphate) was added to the Y4 dropping solution, everything else was the same as in Example 6.
[0049] Comparative Example 4 Except that no acid anhydride (maleic anhydride) was added to the Y4 dropping solution, everything else was the same as in Example 6.
[0050] Comparative Example 5 Except for step A-5, in which a 20wt% hydrochloric acid solution is not used to acidify the matured mixture, everything else is the same as in Example 6.
[0051] Comparative Example 6 Except for the Y4 dripping time range of 0~3 h, everything else is the same as in Example 6.
[0052] Effect test The steel slag-based mineral admixtures obtained in each embodiment and comparative example were tested, and the results are shown in Tables 1, 2, and 3 below. The blanks in Tables 1, 2, and 3 represent the blank groups, which used water as the sample.
[0053] Table 1. Comparison of performance of steel slag-based mineral admixtures in different embodiments and comparative examples. As shown in Table 1, the specific surface area, fluidity ratio, stability, and activity index of the blank group were all lower than the requirements of the national standard. The performance of Examples 1-6 far exceeded the requirements of the national standard, indicating that the admixture of this invention has a significant effect. Comparing Comparative Example 1 with Example 6, it is shown that without the alcohol amine monomer, the grinding aid effect of Comparative Example 1 is worse, and the activity index is lower. Comparing Comparative Example 2 with Example 6, the absence of a five-membered ring monomer in the added liquid prevents effective activation of the RO phase, indicating that the oxygen and nitrogen atoms on the pyrrolidone ring can simultaneously coordinate with an iron ion to form a stable five- or six-membered ring complex structure, which helps promote the hydration of steel slag. Comparing Comparative Example 5 with Example 6, without acid acidification, the steel slag is more difficult to grind, resulting in a smaller specific surface area and lower activity in the later stages. Furthermore, without acid acidification, the free magnesium oxide and calcium oxide inside the steel slag cannot be consumed, thus its stability is unqualified. Compared with Example 6, Comparative Example 6 shows that the Y4 dropping time range is 0~3 h. Introducing acid into the initiation system too early will not only reduce the activity of N-vinylpyrrolidone, but also make it difficult for it to copolymerize and decompose.
[0054] Table 2. Comparison of the performance of steel slag-based mineral admixture concrete in different embodiments and comparative examples (Conch S cement P.O42.5R) Table 3. Comparison of concrete performance of different embodiments and comparative examples using steel slag-based mineral admixtures (Jin Yang Cement P.O42.5R) As shown in Tables 2 and 3, the performance of concrete follows the same pattern as in Table 1. After changing the cement, a comparison of Comparative Example 3, Comparative Example 4, and Example 6 reveals that the absence of phosphate monomers and acid anhydrides (which have good complexing effects) in the Y4 admixture results in decreased concrete spread, workability, and strength properties. This indicates that these two groups improve the compatibility of the admixture.
[0055] In summary, the steel slag-based mineral admixture additive provided in this embodiment of the invention has the following functions: (1) synergistic acid etching and efficient grinding aid, improving grinding efficiency and pre-activating inert components; (2) synergistic effect of multiple adsorption groups, combining dispersibility and highly adaptable water-reducing effect; and (3) specific coordination activation of the iron phase, solving the problem of RO phase hydration inertness. Due to its dense crystal structure and low surface activity, the RO phase is difficult to participate in the reaction in the conventional cement hydration environment, which is a key factor restricting the improvement of the cementitious activity and utilization rate of steel slag admixtures. In the additive of this invention, a functional group with a unique five-membered ring chelate structure is innovatively introduced, which can react with the iron (Fe) released in the RO phase. 2+ / Fe 3+ Metal ions such as iron slag form stable and efficient coordination complexes. This coordination not only disrupts the passivation layer on the surface of RO phase mineral particles, making it easier for internal metal ions to dissolve and participate in the hydration reaction network, but also forms soluble activation intermediates in the liquid phase, promoting the formation and precipitation of gelling hydration products (such as iron-containing CSH gel, calcium aluminoferrite phase, etc.), promoting the transformation of some RO phases from "inert filler" to "active gelling component", improving the overall secondary hydration reaction degree and long-term strength contribution of steel slag, and making it possible to use steel slag in concrete with large dosage and high performance.
[0056] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.
Claims
1. A method for preparing a steel slag-based mineral admixture, characterized in that, Includes the following steps: Polyether monomers and water are mixed, and an initiator is added to obtain a bottom liquid. Under stirring, a mixed solution of alkanolamine monomers and five-membered ring monomers, a mixed solution of carboxyl monomers and sulfonic acid monomers, a mixed solution of chain transfer agent and reducing agent, and a mixed solution of phosphate monomers and acid anhydrides are added dropwise to the bottom liquid for a dropwise reaction. After the dropwise reaction is completed, a heat preservation and aging treatment is performed to obtain an aged mixture. The mixture is then acidified to obtain the steel slag-based mineral admixture additive.
2. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The polyether monomer is at least one of allyl polyoxyethylene ether and methyl allyl polyoxyethylene ether; the mass ratio of the polyether monomer to water is 350~380:250; the initiator is at least one of ammonium persulfate, potassium persulfate and sodium persulfate; the mass ratio of the initiator to water is 1.2-1.8:
250.
3. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The mixed solution of the alkanolamine monomer and the five-membered ring monomer is a mixture of the alkanolamine monomer, the five-membered ring monomer, and water; the alkanolamine monomer is at least one selected from N-(2-hydroxyethyl)acrylamide, N-(2-hydroxypropyl)methacrylamide, N,N-bis(2-hydroxyethyl)-2-acrylamide, and N,N-bis(2-hydroxyethyl)-2-methacrylamide; the five-membered ring monomer is N-vinylpyrrolidone; in the mixed solution of the alkanolamine monomer and the five-membered ring monomer, the mass ratio of the alkanolamine monomer to water is 18-22:40, the mass ratio of the five-membered ring monomer to water is 36-40:40, and the mass ratio of the alkanolamine monomer to the polyether monomer is 18-22:350-380.
4. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The mixed solution of carboxyl monomer and sulfonic acid monomer is a mixture obtained by mixing carboxyl monomer, sulfonic acid monomer and water, and adjusting the pH to 5.5-6.5; the carboxyl monomer is at least one of acrylic acid and methacrylic acid; the sulfonic acid monomer is at least one of 2-acrylamido-2-methylpropanesulfonic acid and sodium propylene sulfonate; in the mixed solution of carboxyl monomer and sulfonic acid monomer, the mass ratio of carboxyl monomer to water is 23-27:45, the mass ratio of sulfonic acid monomer to water is 6-10:45; the mass ratio of carboxyl monomer to polyether monomer is 23-27:350-380.
5. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The mixed solution of the chain transfer agent and the reducing agent is a mixture of the chain transfer agent, the reducing agent and water; the chain transfer agent is at least one of mercaptoethanol and mercaptopropanol; the reducing agent is vitamin C; in the mixed solution of the chain transfer agent and the reducing agent, the mass ratio of the chain transfer agent to water is 0.8-1.2:40, and the mass ratio of the reducing agent to water is 0.4-0.6:
40.
6. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The mixed solution of the phosphate monomer and the acid anhydride is a mixture of the phosphate monomer, the acid anhydride and water; the phosphate monomer is at least one of hydroxyethyl acrylate phosphate and hydroxyethyl methacrylate phosphate; the acid anhydride is at least one of maleic anhydride and itaconic anhydride; in the mixed solution of the phosphate monomer and the acid anhydride, the mass ratio of the phosphate monomer to water is 8-12:50, the mass ratio of the acid anhydride to water is 24-26:50; the mass ratio of the phosphate monomer to the polyether monomer is 8-12:350-380.
7. The method for preparing the steel slag-based mineral admixture according to claim 1, characterized in that, The temperature of the dropwise addition reaction is 60-80℃; the dropwise addition time range of the mixed solution of the alkanolamine monomer and the five-membered ring monomer is 0-1.5h; the dropwise addition time range of the mixed solution of the carboxyl monomer and the sulfonic acid monomer is 0-3h; the dropwise addition time range of the mixed solution of the chain transfer agent and the reducing agent is 0-3h; and the dropwise addition time range of the mixed solution of the phosphate monomer and the acid anhydride is 2-3h.
8. The method for preparing the steel slag-based mineral admixture according to any one of claims 1-7, characterized in that, The temperature for the heat preservation and curing treatment is 60~80℃, and the time for the heat preservation and curing treatment is 1-2 hours; The acidification includes adding an acidic solution to the matured mixture; the acidic solution is a sulfuric acid solution or a hydrochloric acid solution; the mass percentage concentration of the acidic solution is 10-30 wt%.
9. The steel slag-based mineral admixture additive prepared by the preparation method according to any one of claims 1-8.
10. The application of the steel slag-based mineral admixture additive as described in claim 9 in enhancing the activity of steel slag-based mineral admixtures.