Composite functional additive for steel slag, preparation method and steel slag treatment process

Abstract

The application discloses a kind of in-situ crystal phase reconfiguration and active synchronous excitation composite functional additive for steel slag, preparation method and steel slag treatment process, and the composite functional additive includes the following components by weight percentage: composite organosilicon modifier 15%-35%; mechanical force response type organic acid-polymer composite 5%-20%; nano silicon aluminum precursor 10%-25%; auxiliary functional component 2%-10%; the balance is deionized water;Composite organosilicon modifier is compounded by long-chain alkyl trimethylammonium chloride and short-chain alkyl trimethylammonium chloride;Mechanical force response type organic acid-polymer composite is the composite formed by esterification reaction of organic acid and sodium polyacrylate;Nano silicon aluminum precursor includes silicon source precursor and aluminum source precursor.The additive of the application enables the steel slag to obtain ultrafine particle size while generating high-activity hydration crystal nucleus in-situ on its nascent surface and internal defects, achieving one-step completion of grinding and activation.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource utilization and building materials technology, specifically relating to a composite functional additive for steel slag that enables in-situ crystal phase reconstruction and simultaneous activation of activity, its preparation method, and steel slag treatment process. Background Technology

[0002] Steel slag is a major solid waste generated during the iron and steel metallurgical process, with a huge annual emission volume. Grinding steel slag into fine powder and using it as a mineral admixture to partially replace cement in concrete is a major approach for large-scale, high-value-added resource utilization. However, the cementitious activity of steel slag is far lower than that of blast furnace slag, and its application faces a core bottleneck:

[0003] (1) The activation of steel slag is highly dependent on its specific surface area. Traditional processes grind steel slag to a specific surface area >450 m² through physical grinding. 2 / kg, to enhance its hydration activity. However, the grinding process is extremely energy-intensive, and once a certain level of fineness is reached, the activity improvement from continued grinding exhibits a significant "marginal effect," with energy consumption per unit increasing dramatically while activity growth slows down, resulting in poor economic efficiency. The mode of improving activity solely through physical fineness has reached its limit.

[0004] (2) To enhance the activity of steel slag powder, chemical activators, such as sulfates (gypsum) and strong alkalis (NaOH, water glass), are usually compounded during its application. However, this method has obvious drawbacks: ① Limited activation efficiency, as the activator mainly reacts with hydration products in the later stage, contributing little to early strength and not completely activating the inert phase in steel slag; ② Compatibility issues, as the added alkalis and salts may affect the workability, durability (such as alkali-aggregate reaction, efflorescence), and long-term volume stability of concrete; ③ Increased cost, as high-quality chemical activators are expensive.

[0005] (3) Reconstructing the mineral phase of steel slag through high-temperature calcination is another technical route, but it consumes a huge amount of energy, has a complex process, and requires high equipment investment. This runs counter to the original intention of "low carbon" in solid waste resource utilization and is difficult to promote industrially.

[0006] Therefore, existing technologies have resulted in a passive model of "high-energy-consuming grinding + inefficient post-activation." There is an urgent need for an innovative technology that can actively intervene in the physical process of grinding and change the chemical nature of steel slag particles, upgrading the simple "particle size reduction" to "simultaneous completion of particle size reduction and active center construction," fundamentally resolving the contradiction between energy consumption and activity. Summary of the Invention

[0007] To overcome the shortcomings of existing steel slag grinding technologies, such as high energy consumption, low activation efficiency, and reliance on post-processing additives, this invention provides a composite functional additive for steel slag based on the synergistic effect of "mechanical-chemical-in-situ crystal phase reconstruction," its preparation method, and steel slag treatment process. This technology introduces a specially formulated functional additive during the grinding process, enabling the steel slag to achieve ultrafine particle size while simultaneously generating highly active hydrated crystal nuclei in situ at its newly formed surface and internal defects, thus achieving grinding and activation in a single step.

[0008] This invention is achieved as follows: a composite functional additive for steel slag that simultaneously reconstructs and activates in situ crystal phases, comprising the following components by weight percentage: Composite organosilicon modifier 15%-35%; Mechanically responsive organic acid-polymer complexes: 5%-20%; Nano-silicon-aluminum precursor 10%-25%; Auxiliary functional components 2%-10%; The remainder is deionized water; The composite organosilicon modifier is composed of long-chain alkyltrimethylammonium chloride and short-chain alkyltrimethylammonium chloride; the mechanoresponsive organic acid-polymer composite is a composite formed by the esterification reaction of organic acid and sodium polyacrylate; the nano-silicon-aluminum precursor includes a silicon-source precursor and an aluminum-source precursor.

[0009] Furthermore, the long-chain alkyltrimethylammonium chloride has an alkyl carbon chain length of C16-C22 and a weight percentage of 10%-20% in the composite functional additive; the short-chain alkyltrimethylammonium chloride has an alkyl carbon chain length of C8-C12 and a weight percentage of 5%-15% in the composite functional additive.

[0010] Furthermore, the mass ratio of the organic acid to sodium polyacrylate is (2-5):1, the organic acid is one of citric acid, oxalic acid, and tartaric acid, and the molecular weight of sodium polyacrylate is 2000-6000.

[0011] Furthermore, the Si / Al molar ratio in the silicon source precursor and the aluminum source precursor is 1:1 to 5:1; the silicon source precursor is selected from one or two of sodium metasilicate and silica sol, and its weight percentage in the composite functional additive is 5%-15%; the aluminum source precursor is selected from one or two of sodium aluminate and nano boehmite sol, and its weight percentage in the composite functional additive is 3%-10%.

[0012] Furthermore, the auxiliary functional components include a penetration enhancer and a foam stabilizer; the penetration enhancer is diisopropanolamine or triethanolamine, and its weight percentage in the composite functional additive is 1.5%-8%; the foam stabilizer is a silicone defoamer, and its weight percentage in the composite functional additive is 0.5%-2%.

[0013] The present invention also provides a method for preparing the above-mentioned composite functional additive, comprising the following steps: S1. Preparation of mechanically responsive organic acid-polymer complex: Dissolve organic acid and sodium polyacrylate in water, and carry out esterification reaction at 75±15℃ under nitrogen protection and in the presence of a catalyst to obtain the complex. Preparation of nano-silicon-aluminum precursor: Dissolve the silicon source precursor in water to obtain an alkaline silicon-based nanocomposite sol; dissolve the aluminum source precursor in an aqueous solution containing sodium gluconate to obtain a complexed aluminum source; mix the alkaline silicon-based nanocomposite sol and the complexed aluminum source, and adjust the pH to 10.5-11.5 to obtain the nano-silicon-aluminum precursor; S2. Gradient assembly synthesis: Deionized water, composite organosilicon modifier, the obtained mechanically responsive organic acid-polymer composite, and the penetration enhancer in the auxiliary functional components are mixed to form a modified base solution; the obtained nano-silica-alumina precursor is slowly added dropwise to the modified base solution under stirring, and then kept at 55±10℃ for curing; after cooling, the foam stabilizer in the auxiliary functional components is added and the pH is adjusted to 9.0-10.0 to obtain the composite functional additive.

[0014] Furthermore, the amount of catalyst used is 0.2-0.9% of the mass of the organic acid, the catalyst is p-toluenesulfonic acid, and the esterification reaction time is 2-4 hours.

[0015] Furthermore, when the alkaline silicon-based nanocomposite sol and the complexed aluminum source are mixed, the Si / Al molar ratio is controlled to be between 1:1 and 5:1.

[0016] Furthermore, the dropwise acceleration rate of the nano-silicon-aluminum precursor added to the modified base liquid is 1%-5% of the total mass of the composite functional additive system per minute.

[0017] Furthermore, the heat preservation and curing time is ≥1 hour.

[0018] This invention also provides a steel slag treatment process for in-situ phase reconstruction and simultaneous activation, using the aforementioned composite functional additive, and comprising the following steps: P1. Crush the steel slag to the size required for grinding; P2. During the grinding process, a composite functional additive is added to the steel slag. The amount of the composite functional additive added is 0.2%-1.5% of the mass of the steel slag. P3. Grinding is carried out under mechanical force, and the temperature of the grinding material is controlled at 50-130℃, so that the composite functional additives and the newly formed surface of steel slag undergo a mechanical and chemical reaction, simultaneously achieving micronization and in-situ generation of hydrated active crystal nuclei on the surface and subsurface of the particles. P4. The ground material is sorted and collected to obtain highly active steel slag powder.

[0019] Furthermore, step P1 also includes detecting the chemical composition of the steel slag.

[0020] Furthermore, in step P2, the amount of the composite functional additive is determined according to the chemical composition of the steel slag, and the composite functional additive is mixed with the steel slag by atomized spraying or continuous dripping.

[0021] Furthermore, after step P4, the collected highly active steel slag powder is aged for 12-48 hours.

[0022] Compared with the prior art, the present invention has at least the following advantages and positive effects: 1. This invention integrates the traditional two independent and sequential processes of "physical grinding" and "chemical activation" into one step, completing the construction of active centers inside the grinding equipment. This eliminates the need for subsequent large-scale compounding of chemical activators, greatly simplifying the process and improving production efficiency.

[0023] 2. The steel slag micro powder obtained by this invention not only meets the fineness standard, but also has a large number of highly active hydration product nuclei embedded on its surface and inside. These nuclei become "seeds" in the early stage of concrete hydration, significantly accelerating and optimizing the hydration process of the cement-steel slag system. Experiments show that, under the same specific surface area (e.g., 420 m²), 2 Under the condition of ( / kg), the steel slag powder prepared by this invention has a 3-day activity index that is 20%-30% higher than that of products prepared by traditional processes, and a 28-day activity index that can reach S95 level or higher. At the same time, due to the chemical bonding between the crystal nucleus and the steel slag matrix, its activity release is more lasting and more stable.

[0024] 3. Since the improvement of activity no longer depends solely and passively on the ultimate fineness, this invention allows for a moderate reduction in the requirement for the final grinding fineness when the target activity index is achieved. For example, traditional processes require grinding to 500-700 μm. 2 The activity that would otherwise require grinding to 400-450 μm can be achieved with this invention. 2 This can be achieved at / kg. This directly reduces the power consumption of grinding, and the total energy consumption of the system is expected to be reduced by 15%-25%, resulting in significant economic benefits.

[0025] 4. The steel slag powder obtained by this invention exhibits superior dispersibility, water-reducing effect, and compatibility with cement in concrete due to the presence of an organosilicon quaternary ammonium salt modification layer and active crystal nuclei on its surface, thus improving the workability of fresh concrete. Furthermore, the significant increase in early strength facilitates faster turnover of construction formwork. Simultaneously, the optimization of hydration products also contributes to improving the density and durability of concrete (such as resistance to chloride ion penetration and sulfate attack).

[0026] 5. The steel slag treatment process of this invention is carried out at room temperature or medium-low temperature, without high-temperature calcination, which significantly reduces carbon emissions; the amount of additives used is small, and some components are biodegradable or participate in hydration, making it environmentally friendly. This technology opens up a new path for the large-scale, high-value utilization of steel slag. Attached Figure Description

[0027] The technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0028] Figure 1 This is a schematic flowchart of the steel slag treatment process of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All equivalent substitutions or improvements made based on the above-described concepts of this invention should be included within the scope of protection of this invention.

[0030] The embodiments of the present invention provide a composite functional additive for steel slag that simultaneously reconstructs and activates crystal phases in situ. By weight percentage, it comprises the following components: a composite organosilicon modifier, a mechanically responsive organic acid-polymer composite, a nano-silica-alumina precursor, auxiliary functional components, and deionized water.

[0031] Specifically as follows: ① Composite organosilicon modifier 15%-35% Composed of two or more organosilicon quaternary ammonium salts with different chain lengths, including: Long-chain C16-C22 alkyltrimethylammonium chloride (such as octadecyltrimethylammonium chloride) accounts for 10%-20% by weight in composite functional additives; Short-chain C8-C12 alkyltrimethylammonium chloride (such as dodecyltrimethylammonium chloride) accounts for 5%-15% by weight in composite functional additives.

[0032] Its general formula is [R1R2R3R4N] + [X] - Wherein at least one of R1, R2, R3, and R4 is a C8-C22 alkyl chain, and the remainder are methyl or ethyl, [X] - It consists of chloride ions or organic acid anions.

[0033] This composite organosilicon modifier is used to achieve the dual effects of surface modification and penetration enhancement.

[0034] ②Mechanically responsive organic acid-polymer complexes (5%-20%) It is a complex formed by esterification of the pre-reaction product of organic acid and sodium polyacrylate. The mass ratio of organic acid to sodium polyacrylate is (2-5):1, the organic acid is one of citric acid, oxalic acid, and tartaric acid, and the molecular weight of sodium polyacrylate is 2000-6000.

[0035] This mechanically responsive organic acid-polymer complex exhibits pH-responsive and shear dissociation properties.

[0036] ③ Nano-silicon-aluminum precursor 10%-25% Mainly includes: The silicon source precursor is selected from one or two of sodium metasilicate and silica sol (nano SiO2 suspension), and its weight percentage in the composite functional additive is 5%-15%. The aluminum source precursor is selected from one or two of sodium aluminate and nano-boehmite sol, and its weight percentage in the composite functional additive is 3%-10%.

[0037] The Si / Al molar ratio in the silicon source precursor and the aluminum source precursor is 1:1 to 5:1.

[0038] This nano-silicon-aluminum precursor is used to achieve the co-generation of CSH and CAH crystal nuclei.

[0039] ④ Auxiliary functional components 2%-10% Mainly includes: The penetration enhancer, preferably diisopropanolamine or triethanolamine, accounts for 1.5%-8% by weight in the composite functional additive; The foam stabilizer, preferably a silicone defoamer, accounts for 0.5%-2% by weight in the composite functional additive.

[0040] ⑤ Solvents and Carriers The remainder is deionized water.

[0041] This invention also provides a method for preparing the above-mentioned composite functional additive, comprising the following steps: S1: ① Preparation of mechanically responsive organic acid-polymer complex (MAC), aiming to synthesize a polymer complex that can undergo controlled dissociation and release active hydrogen ions under mechanical force.

[0042] First, weigh organic acid (CA) and sodium polyacrylate (PAAS, Mw ≈ 3000) in a reaction flask at a mass ratio of (2-5):1. Add deionized water accounting for 30% of the total mass of the composite functional additives and stir at 200-600 rpm at room temperature until the solid is completely dissolved.

[0043] Next, under nitrogen protection, the above solution is slowly heated to 75±15℃; while continuously stirring, the catalyst p-toluenesulfonic acid (the amount of p-toluenesulfonic acid is 0.2-0.9% of the mass of the organic acid) is added dropwise; at this temperature, the reaction is carried out for 2-4 hours, which promotes the esterification reaction between the carboxyl group (-COOH) in the organic acid molecule and some of the hydroxyl groups at the end of the side chain of sodium polyacrylate or the active sites formed in the aqueous medium, forming a macromolecular complex with ester bond linkage.

[0044] Then, after the reaction was completed, the mixture was cooled to room temperature to obtain a viscous, pale yellow, transparent liquid, namely a mechanically responsive organic acid-polymer complex (MAC).

[0045] ② The preparation of nano-silica-alumina precursors aims to construct a highly active and stable nano-scale aluminosilicate reaction system, providing a "raw material library" for subsequent in-situ crystal nucleation growth.

[0046] First, sodium metasilicate (Na₂SiO₃·9H₂O) is dissolved in deionized water at 60-80℃ to prepare a 10-15 wt% solution. Under high-speed shearing (6000-10000 rpm), silica sol adjusted to pH 4-5 with dilute sulfuric acid is slowly added, with the sodium metasilicate and silica sol mixed at a SiO₂ molar ratio of (1-2):1. The mixture is then treated in an ultrasonic disruptor for 30-60 minutes to form a homogeneous, semi-transparent alkaline silica-based nanocomposite sol (Si-Sol). This alkaline silica-based nanocomposite sol contains both monomeric silicate ions and nano-sized SiO₂ particles, encompassing a multi-level silicon source from ionic to nanoscale.

[0047] Then, sodium aluminate (NaAlO2) is dissolved in an aqueous solution containing 1-10 wt% sodium gluconate to prepare an aluminate solution with a concentration of 5-15 wt%. Sodium gluconate, as a complexing agent, can effectively inhibit the rapid hydrolysis and aggregation of aluminate ions, forming a stable complexed aluminum source.

[0048] Secondly, under vigorous stirring, the prepared alkaline silicon-based nanocomposite sol Si-Sol was slowly added to the prepared complexed aluminum source solution, controlling the Si / Al molar ratio between 1:1 and 5:1 (the specific ratio was adjusted according to the target steel slag composition). During the mixing process, the temperature of the mixture was maintained at 10-40℃, and the pH value was precisely controlled at 10.5-11.5 by adding dilute NaOH solution dropwise. Finally, a clear and stable nano-silicon-aluminum precursor was obtained, with an average particle size of <50 nm.

[0049] S2: Gradient assembly and final synthesis of composite functional additives, achieving the construction of functional gradients by controlling the feeding sequence and process parameters.

[0050] First, in a four-necked flask equipped with a speed-adjustable stirrer and a constant-temperature water bath, add a measured amount of deionized water; heat to 45-85℃, and then add the composite organosilicon modifier (a premix of long-chain and short-chain quaternary ammonium salts), the mechanically responsive organic acid-polymer complex (MAC) obtained in step S1, and the penetration enhancer diisopropanolamine in sequence; stir at 300-1000 rpm for 30-90 minutes to form a homogeneous and transparent modified base solution.

[0051] Then, while maintaining stirring, slowly add the nano-silica-alumina precursor obtained in step S1 from the constant-pressure dropping funnel to the modified base solution at a rate of approximately 1-5% of the total mass of the composite functional additives per minute. This "slow addition" process helps the nano-silica-alumina precursor to be uniformly dispersed and effectively coated in the micelle environment formed by the organosilicon modifier, preventing it from becoming unstable and agglomerating due to excessively high local concentrations.

[0052] Then, after the nano-silicon-aluminum precursor is added, the mixture is controlled at 55±10℃ and kept at this temperature for ≥ 1 hour to promote electrostatic adsorption and self-assembly of the cationic head of the organosilicon quaternary ammonium salt and the anions on the surface of the nano-silicon-aluminum precursor, thus initially forming a prototype structure of "organic modified layer - nano-inorganic core".

[0053] Finally, final conditioning and productization. After the curing time is completed, the mixture is cooled to ≤ 30℃; a silicone defoamer is added, and the pH of the solution is adjusted to 9.0-10.0 with dilute hydrochloric acid or sodium hydroxide solution. The mixture is then discharged, filtered, and packaged under the protection of an inert gas (such as nitrogen) to obtain the composite functional additive.

[0054] This invention also provides a steel slag treatment process using the above-mentioned composite functional additive, comprising the following steps: P1, Preprocessing The steel slag from converters or electric furnaces is subjected to magnetic separation to remove iron and crushed to the particle size required for grinding (e.g., ≤ 10 mm). After crushing, a detection device is added to analyze the content of key components such as CaO, SiO2, and f-CaO in the steel slag in real time, providing data support for subsequent use.

[0055] P2, Additive Dosage and Addition Based on the chemical composition of the steel slag (CaO / SiO2 ratio) and the activity level of the target product, determine the amount of liquid composite functional additive to be added, which is 0.2%-1.5% of the mass of the steel slag. At the feed end or grinding chamber of the grinding equipment, mix the composite functional additive with the steel slag by atomized spraying or continuous dripping.

[0056] Among them, grinding equipment such as vertical roller mills, high-pressure roller mills, ball mills, and roller press combined grinding systems are preferably vertical roller mills or high-pressure roller mills.

[0057] P3, Mechanochemical Co-processing and Activation Grinding is carried out under mechanical force, and the temperature of the ground material is controlled at 50-130℃, so that the composite functional additives and the newly formed surface of steel slag undergo a mechanochemical reaction and facilitate the reaction, simultaneously achieving micronization and in-situ generation of hydrated active crystal nuclei on the surface and subsurface of the particles.

[0058] This process can control the progress of the mechanochemical reaction and the rate and number of crystal nuclei generated by adjusting the grinding intensity (such as mill speed and roller pressure), the addition rate of composite functional additives, and the degree of atomization.

[0059] In the grinding equipment, steel slag is subjected to intense mechanical impact, compression, and shearing. This mechanical force directly disrupts the slag's crystal structure, exposing its active sites. During this process, the composite functional additive undergoes the following synergistic reaction with the newly formed surface of the steel slag: a) Surface modification and dispersion. Organosilicon quaternary ammonium salts are rapidly adsorbed onto the fresh fracture surface of steel slag, preventing particle agglomeration through steric hindrance and improving grinding efficiency. Simultaneously, the following reaction occurs: Steel slag ≡Si-OH + (C8~C22)-Si(OCH3)3·N + (CH3)3Cl - → Steel slag ≡Si-O-Si-(C8~C22)-N + (CH3)3Cl - + 3CH3OH Further formation of surface bonding structures: Steel slag ≡Si-O-Si-(C8~C22)-N + (CH3)3 The short C8-C12 chains fill the gaps between particles and regulate hydrophilicity, while the long C12-C22 chains form a hydrophobic underlayer, thereby inhibiting particle aggregation and optimizing interface properties.

[0060] b) Interfacial chemical erosion. Within the localized high-temperature, high-pressure micro-regions generated by mechanical-thermal coupling, the carboxyl groups (-COOH) of organic acids (such as citric acid) dissociate under stress, releasing H+. + H + Ca dissolved from the surface of steel slag particles 2+ Mg 2+ Al 3+ When metal ions undergo complexation reactions, they form soluble complexes, which continuously damage the silicon-oxygen network and aluminum-oxygen network on the surface of steel slag minerals (such as C2S, C3S, and RO phases), exposing more active sites.

[0061] c) In-situ hydration nucleus formation. Nano-sized silica-alumina precursors (such as sodium metasilicate, sodium aluminate, silica sol, etc.) generate nano-scale hydrated calcium silicate (CSH) gel and hydrated calcium aluminate (CAH) crystal nuclei with high pozzolanic activity in situ at the activation sites of the steel slag under the combined action of the alkaline environment of the steel slag itself and the ions dissolved from interfacial chemical etching. The reaction is as follows: xCa 2+ + ySiO3 2- + zH2O → CSH (gel / nucleus) Ca 2+ + AlO 2- + H2O → CAH (crystal nucleus) These crystal nuclei are chemically bonded to the surface and subsurface of steel slag particles, significantly enhancing the kinetics of subsequent hydration reactions.

[0062] P4. Sorting and Collection The ground material is sorted by an air classifier, and the qualified fine powder is collected as a high-activity steel slag micro powder product. The collected fine powder has a specific surface area ≥ 400 m². 2 / kg.

[0063] The collected highly active steel slag powder is aged for 12-48 hours to further stabilize and develop the surface crystal nuclei.

[0064] To better understand the above embodiments of the present invention, they are further described below.

[0065] Example 1 1. Preparation of composite functional additive GSA-1 (1) Raw materials and proportions (based on the percentage of the total weight of the final composite functional additive product) ① The composite organosilicon modifier is 25%; of which, the long-chain octadecyltrimethylammonium chloride is 15% and the short-chain dodecyltrimethylammonium chloride is 10%.

[0066] ② The mechanically responsive organic acid-polymer complex (MAC) is 10%, wherein the organic acid is citric acid, and the mass ratio of citric acid to sodium polyacrylate is 3:1.

[0067] ③ The nano-silicon-aluminum precursor is 15%; among which, the silicon source precursor is sodium metasilicate (Na2SiO3·9H2O) 8% and silica sol (SiO2 content 30 wt%) 2%; the aluminum source precursor is sodium aluminate (NaAlO2) 5%.

[0068] ④ The auxiliary functional components are 4%; among which, the penetration enhancer diisopropanolamine is 3% and the foam stabilizer polyether modified siloxane defoamer is 1%.

[0069] ⑤ The solvent and carrier are 46% deionized water.

[0070] (2) Preparation process steps S1: Preparation of mechanically responsive organic acid-polymer complexes (MAC) In a 500 mL three-necked flask, add 60 g of deionized water, then add 30 g of citric acid (CA) and 10 g of sodium polyacrylate (PAAS, Mw ≈ 3000) sequentially. Stir at 400 rpm at room temperature until the solid is completely dissolved. Purge the air with nitrogen and maintain a protective atmosphere. Heat the solution in a water bath to 75°C, then slowly add 5 mL of an aqueous solution containing 0.15 g of p-toluenesulfonic acid (PTSA) dropwise through a constant pressure dropping funnel over 1 hour. Maintain the reaction temperature at 75°C and continue stirring for 3 hours. After the reaction is complete, stop heating and allow to cool naturally to room temperature to obtain a viscous, pale yellow, transparent MAC liquid for later use.

[0071] Formulation of nano-silicon-aluminum precursor (SA-Mix) a) Preparation of alkaline silica-based nanocomposite sol (Si-Sol): At 70℃, 16 g of sodium metasilicate nonahydrate was dissolved in 100 g of deionized water to prepare a solution with a concentration of approximately 13.8 wt%. The solution was placed in a stirred tank of a high-speed disperser (9000 rpm), and 13.3 g of commercial silica sol adjusted to pH = 4.5 with dilute sulfuric acid was slowly added under continuous shear. After the addition was complete, the mixture was transferred to an ultrasonic cell disruptor and ultrasonically treated at 500 W for 45 minutes to obtain a uniformly semi-transparent Si-Sol.

[0072] b) Preparation of complexed aluminum source solution: In another container, 10 g of sodium aluminate was dissolved in 88 g of deionized water containing 2 g of sodium gluconate to prepare a stable aluminate solution with a concentration of about 10 wt%.

[0073] c) Synthesis of nano-silicon-aluminum precursor: All Si-Sol obtained in step a) was slowly added dropwise to the complexed aluminum source solution in step b) over 30 minutes under vigorous stirring (600 rpm); the temperature was controlled at 30℃ using a circulating water bath during the mixing process; the pH of the mixture was precisely adjusted to 11.2 using 10 wt% NaOH solution; finally, a clear and stable nano-silicon-aluminum precursor (SA-Mix) was obtained, and its average hydrodynamic particle size was determined to be 32 nm by dynamic light scattering (DLS).

[0074] S2: Gradient assembly synthesis of composite functional additive GSA-1 In a 1 L four-necked flask equipped with a mechanical stirrer, a constant temperature jacket, a dropping funnel, and a nitrogen inlet, 460 g of deionized water was first added; stirring was started (500 rpm) and the temperature was raised to 50 °C; 150 g of octadecyltrimethylammonium chloride, 100 g of dodecyltrimethylammonium chloride, approximately 100 g of the MAC liquid prepared in step S1, and 30 g of diisopropanolamine were added sequentially; the temperature was maintained at 50 °C and stirred for 60 minutes to obtain a homogeneous and transparent modified base solution.

[0075] While keeping the stirring speed constant, transfer all of the SA-Mix prepared in step S1 to a dropping funnel and slowly add it dropwise to a four-necked flask at a rate of about 2 g / min (1% of the total mass of the composite functional additive system) for about 75 minutes.

[0076] After the addition is complete, the mixture is heated to 55°C and kept at this temperature for 90 minutes to mature. After maturation, heating is stopped, and cooling water is circulated to cool the mixture to 25°C. 10 g of polyether-modified siloxane defoamer is added, and the pH of the solution is slowly adjusted to 9.5 with 10 wt% dilute hydrochloric acid solution. The product is discharged under nitrogen protection and filtered through a 200-mesh sieve to obtain a light amber-colored, slightly bluish transparent liquid product, which is the composite functional additive GSA-1.

[0077] 2. Preparation and performance testing of highly active steel slag powder using the composite functional additive GSA-1. Steel slag from a converter in a steel plant was magnetically separated and crushed to a particle size of ≤ 10 mm. Its chemical composition is: CaO 45%, SiO2 15%, Fe2O3 20%, Al2O3 35%, MgO 8%, f-CaO 3%.

[0078] A vertical roller mill was used for grinding. Steel slag was fed into the vertical roller mill at a rate of 50 t / h. Simultaneously, a composite functional additive, GSA-1, accounting for 0.8% of the steel slag mass, was added via a precision atomizing spray gun at the mill inlet. The main motor power of the mill was controlled as required, and the temperature of the material exiting the mill was maintained at approximately 85℃. The ground material was then separated by a built-in dynamic classifier, collecting materials with a specific surface area of ​​410 m². 2 The fine powder was collected at a concentration of / kg and aged in a silo for 24 hours to obtain a sample of highly active steel slag micro powder.

[0079] Using the same steel slag raw material and the same vertical mill system, but without adding any additives, the material is ground to a specific surface area of ​​500 m². 2 / kg, to obtain a traditional steel slag powder sample.

[0080] The activity index of steel slag was tested according to GB / T 18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete". The results are shown in Table 1 below: Table 1 Activity Index Test Data

[0081] As shown in Table 1, the unit product power consumption of the system using the composite functional additive of this invention for steel slag treatment is 32 kWh / t, while the unit product power consumption of the system using the traditional technology is 42 kWh / t. The process of this invention achieves a power consumption reduction of approximately 23.8% even with slightly lower steel slag powder fineness, and significantly improves the activity index across all age stages.

[0082] Example 2 1. Preparation of composite functional additive GSA-2 (1) Raw materials and proportions (based on the percentage of the total mass of the final composite functional additive product) ① The composite organosilicon modifier is 15%; of which, the long-chain octadecyltrimethylammonium chloride is 10% and the short-chain dodecyltrimethylammonium chloride is 5%.

[0083] ② The mechanically responsive organic acid-polymer complex (MAC) is 5%, wherein the organic acid is citric acid, and the mass ratio of citric acid to sodium polyacrylate is 4:1.

[0084] ③ The nano-silicon-aluminum precursor accounts for 25%. Among them, the silicon source precursor is sodium metasilicate (Na2SiO3·9H2O) 11.6% and silica sol (SiO2 content 30 wt%) 5.4%; the aluminum source precursor is sodium aluminate (NaAlO2) 8%.

[0085] ④ The auxiliary functional components are 2%; among which, the penetration enhancer diisopropanolamine is 1.5% and the foam stabilizer polyether modified siloxane defoamer is 0.5%.

[0086] ⑤ The solvent and carrier are 53% deionized water.

[0087] (2) Preparation process steps S1: Preparation of mechanically responsive organic acid-polymer complexes (MAC) In a 500 mL three-necked flask, add 40 g of deionized water, then add 20 g of citric acid (CA) and 5 g of sodium polyacrylate (PAAS, Mw ≈ 3000) sequentially. Stir at 200 rpm at room temperature until the solid is completely dissolved. Purge the air with nitrogen to maintain a protective atmosphere. Heat the above solution to 90 °C in a water bath, and then slowly add 5 mL of an aqueous solution containing 0.18 g of p-toluenesulfonic acid (PTSA) dropwise through a constant pressure dropping funnel over 1 hour. Maintain the reaction temperature at 90 °C and continue stirring for 2 hours. After the reaction is complete, stop heating and allow it to cool naturally to room temperature to obtain a viscous, pale yellow, transparent MAC liquid for later use.

[0088] Formulation of nano-silicon-aluminum precursor (SA-Mix) a) Preparation of alkaline silica-based nanocomposite sol (Si-Sol): 11 g of sodium metasilicate nonahydrate was dissolved in 100 g of deionized water at 60 °C to prepare a solution with a concentration of about 10 wt%. The solution was placed in a stirred tank of a high-speed disperser (6000 rpm), and 10 g of commercial silica sol adjusted to pH = 4.5 with dilute sulfuric acid was slowly added under continuous shear. After the addition was complete, the mixture was transferred to an ultrasonic cell disruptor and ultrasonically treated at 500 W for 30 minutes to obtain a uniformly semi-transparent Si-Sol.

[0089] b) Preparation of complexed aluminum source solution: In another container, 5 g of sodium aluminate was dissolved in 93 g of deionized water containing 2 g of sodium gluconate to prepare a stable aluminate solution with a concentration of about 5 wt%.

[0090] c) Synthesis of nano-silicon-aluminum precursor: All Si-Sol obtained in step a) was slowly added dropwise to the complexed aluminum source solution in step b) over 30 minutes under vigorous stirring (600 rpm); the temperature was controlled at 10℃ using a circulating water bath during the mixing process; the pH of the mixture was precisely adjusted to 11.5 using 10 wt% NaOH solution; finally, a clear and stable nano-silicon-aluminum precursor (SA-Mix) was obtained, and its average hydrodynamic particle size was determined to be 25 nm by dynamic light scattering (DLS).

[0091] S2: Gradient assembly synthesis of composite functional additive GSA-2 In a 1 L four-necked flask equipped with a mechanical stirrer, a thermostatic jacket, a dropping funnel, and a nitrogen inlet, 530 g of deionized water was added first. The stirrer was turned on (500 rpm) and the temperature was raised to 45 °C. 100 g of octadecyltrimethylammonium chloride, 50 g of dodecyltrimethylammonium chloride, approximately 50 g of the MAC liquid prepared in step S1, and 15 g of diisopropanolamine were added sequentially. The temperature was maintained at 45 °C and the mixture was stirred for 30 minutes to obtain a homogeneous and transparent modified base solution.

[0092] While maintaining a constant stirring speed, transfer all of the SA-Mix prepared in step S1 to a dropping funnel and slowly add it dropwise to the reaction flask at a rate of approximately 2 g / min. The dropping process should last approximately 80 minutes.

[0093] After the addition is complete, the mixture is heated to 55°C and kept at this temperature for 90 minutes to mature. After maturation, heating is stopped, and cooling water is circulated to cool the mixture to 25°C. 5 g of polyether-modified siloxane defoamer is added, and the pH of the solution is slowly adjusted to 10 with 10 wt% dilute hydrochloric acid solution. The product is discharged under nitrogen protection and filtered through a 200-mesh sieve to obtain a light amber-colored, slightly bluish transparent liquid product, which is the composite functional additive GSA-2.

[0094] 2. Preparation and performance testing of highly active steel slag powder using composite functional additive GSA-2. Steel slag from a converter in a steel plant was magnetically separated and crushed to a particle size of ≤ 10 mm. Its chemical composition is: CaO 45%, SiO2 15%, Fe2O3 20%, Al2O3 35%, MgO 8%, f-CaO 3%.

[0095] A vertical roller mill was used for grinding. Steel slag was fed into the vertical roller mill at a rate of 50 t / h. Simultaneously, 0.2% (by weight) of the composite functional additive GSA-2 was added via a precision atomizing spray gun at the mill inlet. The main motor power of the vertical mill was controlled as required, and the temperature of the material exiting the mill was maintained at approximately 50℃. The ground material was then separated by a built-in dynamic classifier, collecting materials with a specific surface area of ​​420 m². 2 The fine powder was collected at a concentration of / kg and aged in a silo for 12 hours to obtain a sample of highly active steel slag micro powder.

[0096] Using the same steel slag raw material and the same vertical mill system, but without adding any additives, the material is ground to a specific surface area of ​​700 m². 2 / kg, to obtain a traditional steel slag powder sample.

[0097] The activity index of steel slag was tested according to GB / T 18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete". The results are shown in Table 2 below: Table 2 Activity Index Test Data

[0098] As shown in Table 2, the unit product power consumption of the system using the composite functional additive of this invention for steel slag treatment is 34 kWh / t, while the unit product power consumption of the system using the traditional technology is 60 kWh / t. The process of this invention achieves a significant reduction in power consumption of approximately 43.3% while reducing the fineness of the steel slag powder, and also significantly improves the activity index across all age stages.

[0099] Example 3 1. Preparation of the composite functional additive GSA-3 (1) Raw materials and proportions (based on the percentage of the total mass of the final composite functional additive product) ① The composite organosilicon modifier is 35%; of which, the long-chain octadecyltrimethylammonium chloride is 20% and the short-chain dodecyltrimethylammonium chloride is 15%.

[0100] ② The mechanically responsive organic acid-polymer complex (MAC) is 10%, wherein the organic acid is citric acid, and the mass ratio of citric acid to sodium polyacrylate is 5:1.

[0101] ③ The nano-silicon-aluminum precursor is 10%; among which, the silicon source precursor is sodium metasilicate (Na2SiO3·9H2O) 5% and silica sol (SiO2 content 30 wt%) 2%; the aluminum source precursor is sodium aluminate (NaAlO2) 3%.

[0102] ④ The auxiliary functional components are 6%; among which, the penetration enhancer diisopropanolamine is 5% and the foam stabilizer polyether modified siloxane defoamer is 1%.

[0103] ⑤ The solvent and carrier are 39% deionized water.

[0104] (2) Preparation process steps S1: Preparation of mechanically responsive organic acid-polymer complexes (MAC) In a 500 mL three-necked flask, add 30 g of deionized water, then add 50 g of citric acid (CA) and 10 g of sodium polyacrylate (PAAS, Mw ≈ 3000) sequentially. Stir at 600 rpm at room temperature until the solid is completely dissolved. Purge the air with nitrogen to maintain a protective atmosphere. Heat the above solution to 75°C in a water bath, and then slowly add 5 mL of an aqueous solution containing 0.2 g of p-toluenesulfonic acid (PTSA) dropwise through a constant pressure dropping funnel over 1 hour. Maintain the reaction temperature at 75°C and continue stirring for 4 hours. After the reaction is complete, stop heating and allow it to cool naturally to room temperature to obtain a viscous, pale yellow, transparent MAC liquid for later use.

[0105] Formulation of nano-silicon-aluminum precursor (SA-Mix) a) Preparation of alkaline silica-based nanocomposite sol (Si-Sol): 18 g of sodium metasilicate nonahydrate was dissolved in 100 g of deionized water at 80 °C to prepare a solution with a concentration of about 15 wt%. The solution was placed in a stirred tank of a high-speed disperser (10000 rpm), and 15 g of commercial silica sol adjusted to pH = 4.5 with dilute sulfuric acid was slowly added under continuous shear. After the addition was complete, the mixture was transferred to an ultrasonic cell disruptor and ultrasonically treated at 500 W for 60 minutes to obtain a uniformly semi-transparent Si-Sol.

[0106] b) Preparation of complexed aluminum source solution: In another container, 15 g of sodium aluminate was dissolved in 83 g of deionized water containing 2 g of sodium gluconate to prepare a stable aluminate solution with a concentration of about 15 wt%.

[0107] c) Synthesis of nano-silicon-aluminum precursor: All Si-Sol obtained in step a) was slowly added dropwise to the complexed aluminum source solution in step b) over 30 minutes under vigorous stirring (600 rpm); the temperature was controlled at 40℃ using a circulating water bath during the mixing process; the pH of the mixture was precisely adjusted to 10.5 using 10 wt% NaOH solution; finally, a clear and stable nano-silicon-aluminum precursor (SA-Mix) was obtained, and its average hydrodynamic particle size was determined to be 45 nm by dynamic light scattering (DLS).

[0108] S2: Gradient assembly synthesis of composite functional additive GSA-3 In a 1 L four-necked flask equipped with a mechanical stirrer, a constant temperature jacket, a dropping funnel, and a nitrogen inlet, 390 g of deionized water was added first; stirring was started (500 rpm) and the temperature was raised to 80 °C; 200 g of octadecyltrimethylammonium chloride, 150 g of dodecyltrimethylammonium chloride, approximately 100 g of the MAC liquid prepared in step S1, and 50 g of diisopropanolamine were added sequentially; the temperature was maintained at 80 °C and stirred for 90 minutes to obtain a homogeneous and transparent modified base solution.

[0109] While keeping the stirring speed constant, transfer all of the SA-Mix prepared in step S1 to a dropping funnel and slowly add it dropwise to a four-necked flask at a rate of about 2 g / min for about 75 minutes.

[0110] After the addition is complete, the mixture is kept at 55°C for 90 minutes. After aging, heating is stopped and the mixture is cooled to 25°C by cooling water. 20 g of polyether-modified siloxane defoamer is added, and the pH of the solution is slowly adjusted to 10 with 10% dilute hydrochloric acid solution. The product is discharged under nitrogen protection and filtered through a 200-mesh sieve to obtain a light amber-colored, slightly bluish transparent liquid product, which is the composite functional additive GSA-3.

[0111] 2. Preparation and performance testing of highly active steel slag powder using the composite functional additive GSA-3. Steel slag from a converter in a steel plant was magnetically separated and crushed to a particle size of ≤10 mm. Its chemical composition is as follows: CaO 45%, SiO2 15%, Fe2O3 20%, Al2O3 35%, MgO 8%, f-CaO 3%.

[0112] A vertical roller mill was used for grinding. Steel slag was fed into the mill at a rate of 50 t / h. Simultaneously, 1.5% (by weight) of the composite functional additive GSA-3 (by weight of the steel slag) was added via a precision atomizing spray gun at the mill inlet. The main motor power of the mill was controlled as required, and the temperature of the material exiting the mill was maintained at approximately 100℃. The ground material was then separated by a built-in dynamic classifier, collecting materials with a specific surface area of ​​400 m². 2 The fine powder was collected at a concentration of / kg and aged in a silo for 48 hours to obtain a sample of highly active steel slag micro powder.

[0113] Using the same steel slag raw material and the same vertical mill system, but without adding any additives, the material is ground to a specific surface area of ​​450 m². 2 / kg, to obtain a traditional steel slag powder sample.

[0114] The activity index of steel slag was tested according to GB / T 18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete". The results are shown in Table 3 below: Table 3 Activity Index Test Data

[0115] As shown in Table 3, the unit product power consumption of the system using the composite functional additive of this invention for steel slag treatment is 31 kWh / t, while the unit product power consumption of the system using the traditional technology is 40 kWh / t. The process of this invention achieves a power consumption reduction of approximately 23% even with slightly lower steel slag powder fineness, and significantly improves the activity index across all age stages.

[0116] In summary, the composite functional additive for steel slag, its preparation method, and its steel slag treatment process, which simultaneously achieve in-situ crystal phase reconstruction and activity activation, successfully realize the mechanochemical activation and surface crystal phase reconstruction of steel slag particles during the grinding process. The resulting product achieves significantly higher gelling activity than traditional processes with optimized energy consumption, particularly with a remarkably significant improvement in early-stage activity. This provides a novel technical route for the efficient resource utilization of steel slag, offering substantial economic and environmental benefits.

[0117] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made in accordance with the present invention should still fall within the scope of the present invention.

Claims

1. A composite functional additive for steel slag that simultaneously reconstructs and activates in situ crystal phases, characterized in that, By weight percentage, it contains the following components: Composite organosilicon modifier 15%-35%; Mechanically responsive organic acid-polymer complexes: 5%-20%; Nano-silicon-aluminum precursor 10%-25%; Auxiliary functional components 2%-10%; The remainder is deionized water; The composite organosilicon modifier is composed of long-chain alkyltrimethylammonium chloride and short-chain alkyltrimethylammonium chloride. The mechanically responsive organic acid-polymer complex is a complex formed by the esterification reaction of organic acid and sodium polyacrylate. The nano-silicon-aluminum precursor includes a silicon source precursor and an aluminum source precursor.

2. The composite functional additive according to claim 1, characterized in that, The long-chain alkyltrimethylammonium chloride has an alkyl carbon chain length of C16-C22 and a weight percentage of 10%-20% in the composite functional additive; the short-chain alkyltrimethylammonium chloride has an alkyl carbon chain length of C8-C12 and a weight percentage of 5%-15% in the composite functional additive.

3. The composite functional additive according to claim 1, characterized in that, The mass ratio of the organic acid to sodium polyacrylate is (2-5):1, the organic acid is one of citric acid, oxalic acid, and tartaric acid, and the molecular weight of sodium polyacrylate is 2000-6000.

4. The composite functional additive according to claim 1, characterized in that, The Si / Al molar ratio in the silicon source precursor and the aluminum source precursor is 1:1 to 5:1; the silicon source precursor is selected from one or two of sodium metasilicate and silica sol, and its weight percentage in the composite functional additive is 5%-15%; the aluminum source precursor is selected from one or two of sodium aluminate and nano boehmite sol, and its weight percentage in the composite functional additive is 3%-10%.

5. The composite functional additive according to claim 1, characterized in that, The auxiliary functional components include a penetration enhancer and a foam stabilizer; the penetration enhancer is diisopropanolamine or triethanolamine, and its weight percentage in the composite functional additive is 1.5%-8%; the foam stabilizer is a silicone defoamer, and its weight percentage in the composite functional additive is 0.5%-2%.

6. A method for preparing a composite functional additive for steel slag based on the in-situ crystal phase reconstruction and simultaneous activation of activity as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of mechanically responsive organic acid-polymer complex: Dissolve organic acid and sodium polyacrylate in water, and carry out esterification reaction at 75±15℃ under nitrogen protection and in the presence of a catalyst to obtain the complex. Preparation of nano-silicon-aluminum precursor: Dissolve the silicon source precursor in water to obtain an alkaline silicon-based nanocomposite sol; dissolve the aluminum source precursor in an aqueous solution containing sodium gluconate to obtain a complexed aluminum source; mix the alkaline silicon-based nanocomposite sol and the complexed aluminum source, and adjust the pH to 10.5-11.5 to obtain the nano-silicon-aluminum precursor; S2. Gradient assembly synthesis: Deionized water, composite organosilicon modifier, the obtained mechanically responsive organic acid-polymer composite and the penetration promoter in the auxiliary functional components are mixed to form a modified base solution; the obtained nano-silica aluminum precursor is slowly added dropwise to the modified base solution under stirring, and then the temperature is controlled at 55±10℃ for curing. After cooling, the foam stabilizer from the auxiliary functional components is added and the pH is adjusted to 9.0-10.0 to obtain the composite functional additive.

7. The method for preparing the composite functional additive according to claim 6, characterized in that, The amount of catalyst used is 0.2-0.9% of the mass of the organic acid, the catalyst is p-toluenesulfonic acid, and the esterification reaction time is 2-4 hours.

8. The method for preparing the composite functional additive according to claim 6, characterized in that, When the alkaline silicon-based nanocomposite sol and the complexed aluminum source are mixed, the Si / Al molar ratio is controlled to be between 1:1 and 5:

1.

9. The method for preparing the composite functional additive according to claim 6, characterized in that, The dropleting rate of the nano-silicon-aluminum precursor added to the modified base solution is 1%-5% of the total mass of the composite functional additive system per minute.

10. The method for preparing the composite functional additive according to claim 6, characterized in that, The heat preservation and curing time is ≥1 hour.

11. A steel slag treatment process for in-situ phase reconstruction and simultaneous activation, characterized in that, The composite functional additive used according to any one of claims 1 to 5 comprises the following steps: P1. Crush the steel slag to the size required for grinding; P2. During the grinding process, a composite functional additive is added to the steel slag. The amount of the composite functional additive added is 0.2%-1.5% of the mass of the steel slag. P3. Grinding is carried out under mechanical force, and the temperature of the grinding material is controlled at 50-130℃, so that the composite functional additives and the new surface of steel slag undergo a mechanical and chemical reaction, simultaneously achieving micronization and in-situ generation of hydrated active crystal nuclei on the particle surface and subsurface. P4. The ground material is sorted and collected to obtain highly active steel slag powder.

12. The steel slag treatment process according to claim 11, characterized in that, Step P1 also includes detecting the chemical composition of the steel slag.

13. The steel slag treatment process according to claim 11, characterized in that, In step P2, the amount of the composite functional additive is determined according to the chemical composition of the steel slag, and the composite functional additive is mixed with the steel slag by atomized spraying or continuous dripping.

14. The steel slag treatment process according to claim 11, characterized in that, After step P4, the process also includes aging the collected highly active steel slag powder for 12-48 hours.

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