An ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polished slag and a preparation method thereof

Abstract

The application relates to the technical field of solid waste admixture, and specifically discloses an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polished slag and a preparation method thereof.The ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polished slag comprises the following raw materials in parts by weight: modified converter steel slag 280-350 parts, modified polished slag 100-140 parts, electrolytic manganese slag 70-90 parts, low-calcium high-iron cement clinker 90-110 parts, desulfurization gypsum 40-60 parts, nano silicon dioxide 10-30 parts and steel slag-based composite activator 20-40 parts.The preparation method comprises the following steps: S1, airflow classification coupling two-stage ball milling; and S2, microwave-assisted carbonization treatment.The admixture can be used for building material concrete, and has the advantages of high solid waste synergistic activation efficiency, high solid waste utilization rate, rich functionality of the admixture and the like.

Description

Technical Field

[0001] This application relates to the technical field of solid waste admixtures, and more specifically, it relates to an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag and its preparation method. Background Technology

[0002] my country's steel industry generates over 150 million tons of converter steel slag annually, while the ceramic tile industry generates over 30 million tons of polishing slag annually. Both types of solid waste are major industrial solid wastes. Currently, the resource utilization rate of converter steel slag is less than 50%, and the utilization rate of polishing slag is less than 30%. Stockpiling and disposal occupy land resources and easily lead to environmental and safety problems such as heavy metal leaching, dust diffusion, and soil alkalization. Converter steel slag contains cementitious active components such as CaO and Fe2O3, and has hydration reaction potential. However, it has problems such as dense particle surfaces and high content of free calcium oxide (f-CaO). When used alone as a cementitious component, it can easily lead to poor volume stability and shrinkage cracking in concrete. Polishing slag is rich in SiO2 and aluminosilicate glass, with significant advantages in particle morphology and gradation, which can improve the density of materials. However, it has low hydration activity and is inert, making it difficult to use alone as a cementitious material.

[0003] Ultra-high performance concrete (UHPC) possesses high strength and high durability, but its traditional admixtures (silica fume, quartz powder, etc.) suffer from drawbacks such as high cost, limited functionality, and high energy consumption in preparation and curing. Conventional high-temperature steam curing consumes more than 500 kWh / ton, hindering engineering applications and the promotion of low-carbon practices. Existing industrial solid waste admixture technologies mostly focus on the activation of single solid wastes or modification with traditional activators, resulting in the following technical bottlenecks: First, the synergistic activation efficiency of multiple solid wastes is low, and the volume stability problem caused by converter steel slag f-CaO and the inert activation problem of polishing slag are difficult to solve synergistically; second, the admixtures have limited functionality, making it difficult to meet the requirements of heavy metal solidification and high durability in contaminated sites, marine engineering, and other scenarios; third, the energy consumption of preparation and curing processes is relatively high, and the airflow classification and curing processes lack efficient and low-consumption optimization, limiting industrial applications.

[0004] To address the above problems, existing technologies have proposed some improvement solutions.

[0005] CN121758083A discloses a method for designing the composition ratio of a slag-based cementitious material, using slag as the main component and synergistically preparing the cementitious material through sulfate donors, alkali activators, and early-strength agents. This scheme is designed for slag systems. However, slag and converter steel slag differ significantly in mineral composition and hydration mechanism. The slag lacks the volume stability of f-CaO and the dense, inert surface layer characteristic of converter steel slag, thus failing to achieve synergistic activation of converter steel slag and polishing slag, and does not address the high-value synergistic utilization of these two types of bulk solid waste.

[0006] CN112456848A discloses a steel slag micronized powder activation agent and its preparation method, which uses an alkaline activator and a sulfate activator to construct a binary composite activation system to enhance the activity of steel slag micronized powder. This method only addresses a single steel slag system and does not disclose a specific ternary activation system composed of converter steel slag micronized powder, potassium silicate, and aluminum sulfate. It does not solve the problem of inert activation of polishing slag, nor does it achieve the recycling of steel slag as the core component of the activator.

[0007] CN110903043B discloses a composite steel slag activator and its preparation method and application, which aims to improve the hydration activity of steel slag. However, it is still limited to a single steel slag system and does not involve the synergistic activation of multiple solid wastes such as converter steel slag, polishing slag and electrolytic manganese slag. It does not construct a heavy metal solidification function and does not adopt a multi-dimensional coupled activation and low-energy consumption preparation process, making it difficult to achieve both performance improvement and low-carbon preparation at the same time.

[0008] In summary, existing technologies have not yet been able to achieve the synergistic and efficient activation of solid wastes from both converter steel slag and polishing slag, and cannot simultaneously achieve the five core objectives of "high solid waste content, high mechanical properties, high durability, heavy metal solidification function, and low energy consumption preparation". There is an urgent need to develop a new type of admixture that combines synergistic activation of steel and ceramic tile solid wastes with functional expansion and low energy consumption process to fill the industry gap. Summary of the Invention

[0009] To address the issues of low synergistic activation efficiency of multiple solid wastes, limited functionality of admixtures, and high energy consumption in admixture preparation processes, this application provides an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag and its preparation method, employing the following technical solution:

[0010] In a first aspect, this application provides an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising the following raw materials in parts by weight:

[0011] 280-350 parts of modified converter steel slag;

[0012] 100-140 parts of modified polishing residue;

[0013] 70-90 parts of electrolytic manganese slag;

[0014] 90-110 parts of low-calcium high-iron cement clinker;

[0015] 40-60 parts of desulfurized gypsum;

[0016] 10-30 parts of nano-silica;

[0017] 20-40 parts of steel slag-based composite activator.

[0018] Optionally, an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag comprises the following raw materials in parts by weight:

[0019] 300-340 parts of modified converter steel slag;

[0020] 110-130 parts of modified polishing residue;

[0021] 75-85 parts of electrolytic manganese slag;

[0022] 90-105 parts of low-calcium high-iron cement clinker;

[0023] 45-55 parts of desulfurized gypsum;

[0024] 15-25 parts of nano-silica;

[0025] 25-35 parts of steel slag-based composite activator.

[0026] Optionally, an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag comprises the following raw materials in parts by weight:

[0027] 320 parts of modified converter steel slag;

[0028] 120 parts of modified polishing residue;

[0029] 80 parts of electrolytic manganese slag;

[0030] 100 parts of low-calcium high-iron cement clinker;

[0031] 50 parts of desulfurized gypsum;

[0032] 20 parts of nano-silica;

[0033] 30 parts of steel slag-based composite activator.

[0034] Optionally, the modified converter slag is modified converter slag that has undergone ultrasonic-plasma synergistic treatment.

[0035] By adopting the above technical solution, the ultrasonic-plasma synergistic pretreatment used in this invention is not a simple superposition of two conventional activation methods: the cavitation effect of ultrasound can generate high-speed microjets, knocking away the dense inert hydration product layer on the surface of converter steel slag, exposing the internal active mineral phase, and at the same time opening the closed-pore structure inside the steel slag, providing a channel for plasma etching; the low-temperature plasma, under the protection of N2 atmosphere, can perform directional etching on the fresh surface of steel slag, generating a large number of dangling bonds and active sites, significantly increasing the glass content. At the same time, the thermal effect of plasma can promote the pre-digestion of f-CaO, reducing its content to below 1.5 wt%, fundamentally solving the industry pain point of poor volume stability of steel slag. Under the synergistic effect of the two, the improvement in steel slag activity far exceeds that of single ultrasonic or single plasma treatment, overcoming the technical prejudice in this field that "single physical activation cannot simultaneously solve the problems of steel slag surface density and f-CaO".

[0036] Optionally, the modified polishing slag is modified polishing slag that has undergone microwave-ball milling combined treatment.

[0037] By adopting the above technical solution, the core defect of polishing slag is its stable silica-alumina glassy network structure and strong hydration inertness. Conventional ball milling can only achieve physical refinement and cannot break its stable Si-O-Si bonds. This invention uses a microwave-ball milling combined pretreatment. The selective heating effect of microwaves can generate thermal stress in the polar mineral phases inside the polishing slag, leading to microcracks in the glassy network and reducing the Si-O bond energy. The subsequent ball milling process can achieve efficient refinement along the microcracks, while further breaking down the damaged glassy network and releasing active silica-alumina components. Compared with conventional single ball milling, the activity of polishing slag is increased by more than 40% under the same grinding time, solving the industry problem that polishing slag is difficult to use as a cementing active component.

[0038] Optionally, the modified polishing slag has a SiO2 content of ≥65wt% and a particle size of <40μm of ≥95%.

[0039] Optionally, the preparation method of the steel slag-based composite activator is as follows: take converter steel slag and obtain steel slag powder by magnetic separation, grinding and calcination, mix the steel slag powder with potassium silicate and aluminum sulfate, and obtain the steel slag-based composite activator by stirring and crushing.

[0040] By adopting the above technical solution, the steel slag-based composite activator achieves an activation efficiency far exceeding that of ordinary chemical activators through a "waste-to-waste" approach. Furthermore, it can fix heavy metals in solid waste, effectively preventing problems such as subsequent cracking, efflorescence, and heavy metal leaching that pollute the environment. The steel slag-based composite activator can hydrate to form a dense network gel structure interwoven with CSH gel and AFt, effectively improving the product's strength, freeze-thaw resistance, and impermeability. It also utilizes the network structure to dual-lock heavy metals, while simultaneously reducing costs and increasing the overall utilization rate of solid waste.

[0041] Optionally, the mass ratio of the steel slag powder, potassium silicate, and aluminum sulfate is 4:3:1-2.

[0042] By adopting the above technical solution, the proportion of each component in the steel slag-based composite activator was optimized. Within this proportion, the activation effect of the steel slag-based composite activator is stable throughout the process. It can generate CSH gel and AFt with sufficient aluminum sulfate to supplement strength and lock porosity, and will not cause expansion and cracking in the later stage due to excessive dosage, thus obtaining activation stability far exceeding that of single alkali activation.

[0043] Secondly, this application provides a method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, using the following technical solution:

[0044] A method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag includes the following steps:

[0045] S1. Preparation of modified converter steel slag:

[0046] Modified converter steel slag is obtained by magnetic separation to remove iron and crushing, followed by ultrasonic-plasma synergistic treatment under N2 protection.

[0047] S2. Preparation of modified polishing slag:

[0048] After the polishing slag is screened to remove impurities and crushed, it is subjected to microwave treatment and ball milling in sequence to obtain modified polishing slag.

[0049] S3, airflow-stage coupled two-stage ball mill:

[0050] Primary ball milling: Modified converter steel slag, modified polishing slag, electrolytic manganese slag, and desulfurized gypsum are added to a ball mill and ground to obtain primary powder.

[0051] Air classifier: The primary powder is fed into the air classifier, and the cutting particle size is set to 10μm to remove coarse particles;

[0052] Secondary ball milling: Low-calcium high-iron cement clinker, nano-silica, and steel slag-based composite activator are added to the classified powder, and then ground to obtain the final powder;

[0053] S4. Microwave-assisted carbonization treatment: Place the final powder in a microwave curing chamber, first microwave curing at 50℃ (power 800W) for 4 hours, then introduce 25% CO2 gas for carbonization curing for 10 hours (microwave power 300W continuously assisted), and after cooling to room temperature, it becomes industrial solid waste admixture.

[0054] Optionally, the operating parameters of the air classifier in step S3 are: air volume 15-20 m³ / h, classifier speed 3000-3500 r / min, and feed rate 50-60 kg / h.

[0055] Optionally, in step S4, the humidity of the microwave-assisted carbonization process is controlled at 90%-95%, and the CO2 gas flow rate is 2-3 L / min.

[0056] Optionally, the final powder properties can be tested: specific surface area 850-900 m² / kg, average particle size 3.0-3.5 μm, and average roundness > 0.99.

[0057] Optionally, modified converter steel slag preparation: the converter steel slag is magnetically separated to remove iron, crushed to a particle size of <5mm, and fed into an integrated ultrasonic-plasma reactor. It is then treated under N2 protection according to the parameters (ultrasonic 450W, 18min; plasma 380W, 14min) to obtain modified converter steel slag.

[0058] Optionally, the modified polishing slag is prepared by screening and removing impurities, crushing it to a particle size of <5mm, feeding it into a microwave reactor (600W) for 6 minutes, then ball milling it for 20 minutes, and naturally cooling it to obtain the modified polishing slag.

[0059] Optional modification of electrolytic manganese slag: Electrolytic manganese slag is fed into a microwave reactor (600W) and treated for 6 minutes, followed by natural cooling.

[0060] In summary, this application has the following beneficial effects:

[0061] 1. High solid waste utilization rate: The total amount of three types of industrial solid waste, namely converter steel slag, polishing slag and electrolytic manganese slag, reaches 75%~80%. When the annual production capacity is 100,000 tons, it can reduce the stockpiling of solid waste by 80,000 tons, realize the synergistic high-value utilization of bulk solid waste in the steel and ceramic tile industry, and solve the environmental problems of traditional landfill.

[0062] 2. Cost and energy consumption are reduced: The cost of steel slag-based composite activator is about RMB 1,500 per ton, which is much lower than that of silica fume. The overall cost of admixtures is reduced by 45% compared with traditional solutions. Microwave-assisted carbonization treatment replaces high-temperature steam curing, reducing energy consumption by 30%. With an annual production capacity of 100,000 tons, electricity costs can be saved by more than RMB 150,000.

[0063] 3. Synergistic Improvement of Performance and Function: For the first time, "structural-functional integration" (load-bearing capacity + heavy metal curing + high durability) of ultra-high performance concrete is achieved. The prepared UHPC has a 28-day compressive strength ≥140MPa, a strength loss rate of <4% after 300 freeze-thaw cycles, and Pb²+ and Cr... 6 With a solidification rate of over 92% for heavy metals, it can be extended to harsh scenarios such as contaminated sites and marine engineering.

[0064] 4. Stable product performance: The airflow classification coupled two-stage ball milling process ensures uniform particle size distribution of the powder, with a standard deviation of particle size distribution <0.5μm. The 28-day compressive strength fluctuation of 5 batches of products is <2MPa, meeting the requirements of continuous industrial production; the f-CaO content of the modified converter steel slag is ≤1.5wt%, which completely solves the problem of steel slag volume stability. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the heat release rate of the two cementing materials in Example 2 and Comparative Example 2 of this application;

[0066] Figure 2 This is a schematic diagram showing the cumulative heat release of the two cementing materials in Example 2 and Comparative Example 2 of this application. Detailed Implementation

[0067] The present application will be further described in detail below with reference to the embodiments.

[0068] Example

[0069] Example 1

[0070] On the one hand, this application provides an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising 300 kg of modified converter steel slag, 110 kg of modified polishing slag, 75 kg of electrolytic manganese slag, 95 kg of low-calcium high-iron cement clinker, 45 kg of desulfurized gypsum, 15 kg of nano silica and 25 kg of steel slag-based composite activator.

[0071] On the other hand, this application provides a method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising the following steps:

[0072] S1. Pretreatment: Magnetic separation to remove iron from converter steel slag, crushing to <5mm, N2 protection in UPR-500 reactor, ultrasonic probe insertion depth to 1 / 2 of material height, plasma electrode distance from material 5-8mm, ultrasonic power 400W, treatment for 15min, plasma power 350W, treatment for 12min, to obtain modified converter steel slag (f-CaO content 1.2wt%).

[0073] S2. Polishing slag is screened to remove impurities, crushed to <5mm, microwaved at 600W for 6min, and then ball-milled for 20min to obtain modified polishing slag (SiO2 content 66wt%, <40μm particles account for 96%); electrolytic manganese slag is microwaved at 600W for 6min, and after cooling, 96% of the particles are <35μm.

[0074] S3. Ball Milling and Classification: First-stage ball milling: Modified converter steel slag, modified polishing slag, electrolytic manganese slag, and desulfurized gypsum are taken and ground at 350 r / min for 35 min at a ball-to-material ratio of 6:1 (zirconia balls 4mm / 9mm=1:2) to obtain primary powder; Air classification: FLS-100 machine (air volume 18m³ / h, classifying wheel 3200r / min, feed 55kg / h) to remove particles >10μm; Second-stage ball milling: Cement clinker, nano silica, and steel slag-based composite activator are added and ground at 500 r / min for 25 min at a ball-to-material ratio of 9:1 (zirconia balls 2mm / 7mm=1:3) to obtain final powder with a specific surface area of ​​850m² / kg, particle size of 3.5μm, and roundness of 0.991;

[0075] S4. Curing: Place the final powder in a microwave curing chamber and cure it at 50℃ / 800W for 4 hours. Then, introduce 25% CO2 (flow rate 2.5L / min) for carbonization for 10 hours (300W microwave assisted). After cooling, the blended material is obtained.

[0076] The preparation method of the steel slag-based composite activator is as follows: After magnetic separation to remove iron from converter steel slag, it is ground to a particle size of <1mm and calcined at 800℃ for 2h to obtain steel slag micro powder; the steel slag micro powder is mixed with potassium silicate (concentration 40wt%) and aluminum sulfate (analytical grade) at a mass ratio of 4:3:2, added to a planetary mixer (speed 600r / min) and stirred for 30min, vacuum dried (80℃, -0.08MPa) and then pulverized to a particle size of <10μm to obtain the steel slag-based composite activator.

[0077] Example 2

[0078] On the one hand, this application provides an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising 320 kg of modified converter steel slag, 120 kg of modified polishing slag, 80 kg of electrolytic manganese slag, 100 kg of low-calcium high-iron cement clinker, 50 kg of desulfurized gypsum, 20 kg of nano-silica, and 30 kg of steel slag-based composite activator.

[0079] On the other hand, this application provides a method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising the following steps:

[0080] S1. Pretreatment: Magnetic separation to remove iron from converter steel slag, crushing to <5mm, N2 protection in UPR-500 reactor, ultrasonic probe insertion depth to 1 / 2 of material height, plasma electrode distance from material 5-8mm, ultrasonic power 450W, treatment for 18min, plasma power 380W, treatment for 14min, to obtain modified converter steel slag (f-CaO content 1.0wt%).

[0081] S2. Polishing slag is screened to remove impurities, crushed to <5mm, microwaved at 600W for 6min, and then ball-milled for 20min to obtain modified polishing slag (SiO2 content 68wt%, <40μm particles account for 97%); electrolytic manganese slag is microwaved at 600W for 6min, and after cooling, the particle size <35μm accounts for 96%;

[0082] S3. Ball Milling and Classification: First-stage ball milling: Modified converter steel slag, modified polishing slag, electrolytic manganese slag, and desulfurized gypsum are taken and ground at 350 r / min for 35 min with a ball-to-material ratio of 6:1 (zirconia balls 4mm / 9mm=1:2) to obtain primary powder; Air classification: FLS-100 machine (air volume 18m³ / h, classifying wheel 3200r / min, feed 55kg / h) to remove particles >10μm; Second-stage ball milling: Cement clinker, nano silica, and steel slag-based composite activator are added and ground at 500 r / min for 25 min with a ball-to-material ratio of 9:1 (zirconia balls 2mm / 7mm=1:3) to obtain final powder with a specific surface area of ​​880m² / kg, particle size of 3.2μm, and roundness of 0.992;

[0083] S4. Curing: Place the final powder in a microwave curing chamber at 50℃ / 800W for 4 hours, then introduce 25% CO2 (flow rate 2.5L / min) for carbonization for 10 hours (300W microwave assisted), and cool to obtain the blend.

[0084] The preparation method of the steel slag-based composite activator is as follows: After magnetic separation to remove iron from converter steel slag, it is ground to a particle size of <1mm and calcined at 800℃ for 2h to obtain steel slag micro powder; the steel slag micro powder is mixed with potassium silicate (concentration 40wt%) and aluminum sulfate (analytical grade) at a mass ratio of 4:3:2, added to a planetary mixer (speed 600r / min) and stirred for 30min, vacuum dried (80℃, -0.08MPa) and then pulverized to a particle size of <10μm to obtain the steel slag-based composite activator.

[0085] Example 3

[0086] On the one hand, this application provides an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising 340 kg of modified converter steel slag, 130 kg of modified polishing slag, 85 kg of electrolytic manganese slag, 105 kg of low-calcium high-iron cement clinker, 55 kg of desulfurized gypsum, 25 kg of nano-silica, and 35 kg of steel slag-based composite activator.

[0087] On the other hand, this application provides a method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, comprising the following steps:

[0088] S1 pretreatment: Converter slag is magnetically separated to remove iron and crushed to <5mm. It is then placed in a UPR-500 reactor under N2 protection. The ultrasonic probe is inserted to a depth of 1 / 2 of the material height, the distance between the plasma electrode and the material is 5-8mm, the ultrasonic power is 500W, and the treatment lasts for 20min. The plasma power is 400W, and the treatment lasts for 15min to obtain modified converter slag (f-CaO content 0.9wt%).

[0089] S2. Polishing slag is screened to remove impurities, crushed to <5mm, microwaved at 600W for 6min, and then ball-milled for 20min to obtain modified polishing slag (SiO2 content 67wt%, <40μm particles account for 96%); electrolytic manganese slag is microwaved at 600W for 6min, and after cooling, 96% of the particles are <35μm.

[0090] S3. Ball Milling and Classification: Ball Milling and Classification: First-stage ball milling: Modified converter steel slag, modified polishing slag, electrolytic manganese slag and desulfurized gypsum are taken and ground at 350 r / min for 35 min with a ball-to-material ratio of 6:1 (zirconia balls 4mm / 9mm=1:2) to obtain primary powder; Air classification: FLS-100 machine (air volume 18m³ / h, classifying wheel 3200r / min, feed 55kg / h) to remove particles >10μm; Second-stage ball milling: Cement clinker, nano silica and steel slag-based composite activator are added and ground at 500 r / min for 25 min with a ball-to-material ratio of 9:1 (zirconia balls 2mm / 7mm=1:3) to obtain final powder with a specific surface area of ​​900m² / kg, particle size of 3.0μm and roundness of 0.994;

[0091] S4. Curing: Place the final powder in a microwave curing chamber at 50℃ / 800W for 4 hours, then introduce 25% CO2 (flow rate 2.5L / min) for carbonization for 10 hours (300W microwave assisted), and cool to obtain the blend.

[0092] The preparation method of the steel slag-based composite activator is as follows: After magnetic separation to remove iron from converter steel slag, it is ground to a particle size of <1mm and calcined at 800℃ for 2h to obtain steel slag micro powder; the steel slag micro powder is mixed with potassium silicate (concentration 40wt%) and aluminum sulfate (analytical grade) at a mass ratio of 4:3:2, added to a planetary mixer (speed 600r / min) and stirred for 30min, vacuum dried (80℃, -0.08MPa) and then pulverized to a particle size of <10μm to obtain the steel slag-based composite activator.

[0093] Comparative Example

[0094] Comparative Example 1

[0095] The difference between this comparative example and Example 2 is that the admixture in this comparative example includes 320 kg of converter steel slag, 120 kg of stainless steel slag, 100 kg of cement clinker, and 10 kg of sodium hydroxide activator. The preparation method is to mix them and then perform a single ball milling (300 r / min, 60 min), followed by steam curing at 80°C for 12 h to obtain the admixture.

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 2 is that the admixture in this comparative example includes 350 kg of stainless steel slag, 135 kg of red mud, 90 kg of electrolytic manganese slag, 110 kg of cement clinker, 25 kg of nano-calcium carbonate, and 35 kg of composite activator. The preparation method is as follows: after mixing the above materials, they are subjected to low-temperature plasma treatment, followed by two-stage ball milling and steam carbonization to obtain the admixture.

[0098] Among them: Low-temperature plasma treatment step: Single low-temperature plasma treatment is adopted, the treatment object is stainless steel slag, the parameters are: plasma power 380W, treatment time 14min, N2 inert protection, electrode-material distance 5-8mm, no ultrasonic synergy.

[0099] Ball milling parameters: Conventional two-stage ball milling was used. First-stage ball milling: ball-to-material ratio 6:1 (4mm / 9mm zirconia balls 1:2), grinding at 350r / min for 35min; Second-stage ball milling: ball-to-material ratio 9:1 (2mm / 7mm zirconia balls 1:3), grinding at 500r / min for 25min; There was no airflow classification step to remove coarse particles throughout the process, and the other parameters were completely consistent with those in Example 2.

[0100] Steam carbonization curing parameters: Conventional steam carbonization is used. First, saturated steam is used for curing at 60℃ for 6 hours, followed by constant temperature carbonization at 40℃ for 10 hours with 25% CO2 concentration. The curing humidity is 90%-95%, and the CO2 flow rate is 2.5L / min. There is no microwave continuous auxiliary process.

[0101] Performance testing

[0102] The UHPC mix design is as follows: water-cement ratio 0.165, cementitious material 1180 kg / m³, cement-sand ratio 1:1.1, water-reducing agent 1.7%, steel fiber 2.2%, and Pb²+ (50 mg / kg) and Cr. 6 + (10mg / kg) simulates a polluted environment, and the technical solution and technical effects of the present invention are illustrated by comparison.

[0103] (1) Compressive strength test: The compressive strength shall be tested in accordance with GB / T 50081-2019 (Standard for Test Methods of Physical and Mechanical Properties of Concrete).

[0104] (2) Freeze-thaw performance test: The freeze-thaw performance was tested in accordance with GB / T 50082-2009 Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete.

[0105] (3) Adsorption performance test: The adsorption performance was tested according to the "HJ 557-2010 Solid waste leaching toxicity leaching method horizontal oscillation method".

[0106] Table 1 Performance Testing

[0107] 28-day compressive strength / MPa Loss rate after 300 freeze-thaw cycles / % Pb²⁺ Curing Rate / % <![CDATA[Cr 6 +Cure Rate / %]]> Example 1 146.3 4.0 92.1 92.2 Example 2 149.2 3.8 94.5 93.2 Example 3 145.5 3.5 95.3 94.1 Comparative Example 1 142.7 8.5 0 0 Comparative Example 2 139.3 4.2 21.3 22.5

[0108] By comparing the performance test results in Table 1, we can find that:

[0109] 1. As can be seen from the above data, the performance of the ultra-high performance concrete of Examples 1-3 of the present invention is significantly better than that of Comparative Example 1 and Comparative Example 2, which proves that the present invention effectively improves the cementitious activity of admixtures through the synergistic activation of converter steel slag-polishing slag and process innovation, and achieves synergistic improvement of UHPC strength, durability and heavy metal curing function.

[0110] 2. The ternary solid waste system of converter steel slag-polishing slag-electrolytic manganese slag of the present invention is not a simple mixture of solid wastes, but rather forms a precise complementarity of hydration components: converter steel slag provides a high content of CaO, providing an alkaline environment and calcium source for the hydration system; polishing slag provides a high content of active SiO2 and Al2O3, serving as the core silicon and aluminum source for the hydration reaction, while its excellent particle morphology can optimize the system gradation and improve density; electrolytic manganese slag provides soluble sulfates and trace amounts of manganese ions, which can act as a catalyst for the hydration reaction, accelerating the hydration rate of tricalcium silicate and dicalcium silicate, while sulfates can further supplement the sulfate activation effect. The three components synergistically form a complete hydration closed loop, with a total solid waste content of 75%~80%, far exceeding the solid waste content level of similar solid waste admixtures in the prior art.

[0111] 3. The steel slag-based composite activator of the present invention is not a conventional alkali-sulfate binary activation system in the art, but rather forms a ternary synergistic activation system of "nucleus induction - alkaline activation - sulfate activation". Furthermore, the specific ratio of 4:3:2 is the optimal parameter obtained through extensive orthogonal experiments, and is not a conventional choice in the art. Specifically, calcined steel slag powder can act as hydration nuclei, inducing the directional growth of hydration products and accelerating the hydration rate, while simultaneously achieving closed-loop utilization of steel slag and reducing activator costs. The OH- ions released from potassium silicate can continuously disrupt the glassy network structure in steel slag and polishing slag, releasing active Ca2+. 2+ SiO4 4 Al⁻ and AlO⁻ ions provide raw materials for the hydration reaction; aluminum sulfate provides Al 3+ and SO4 2- It can react with Ca in the hydration system 2+ The reaction generates needle-like ettringite crystals, which fill the internal pores of the material, increasing its density. Simultaneously, ettringite can solidify Pb in the system through both physical encapsulation and chemical coordination. 2+ Cr 6+ The system contains heavy metal ions. Under the synergistic effect of these three factors, the hydration heat release of the hydration system after 72 hours is increased by more than 35% compared with the conventional binary activation system, while achieving a synergistic improvement in mechanical properties and heavy metal curing performance.

[0112] 4. The present invention employs a complete process of "ultrasonic-plasma synergistic pretreatment → airflow-stage coupled two-stage ball milling → microwave-assisted carbonization treatment," achieving a synergistic optimization of low energy consumption and high performance. The airflow-stage coupled two-stage ball milling process first achieves coarse grinding and refinement of bulk solid waste through ball milling. After airflow-stage removal of coarse particles, the functional components are then finely ground through two-stage ball milling. Compared with conventional single ball milling, the grinding efficiency is increased by 50%, energy consumption is reduced by 25%, and precise control of powder particle size is achieved, with a particle size distribution standard deviation of <0.5μm. This ensures stable product performance. The microwave-assisted carbonization process replaces the conventional high-temperature steam curing in existing technologies. The volume heating effect of microwaves can make the material heat up evenly inside, accelerating the early hydration rate. Subsequently, microwave-assisted carbonization can make CO2 diffuse evenly into the material, reacting with f-CaO and Ca(OH)2 to generate calcium carbonate crystals, further solidifying free calcium, improving volume stability, and filling internal pores. This process reduces energy consumption per ton by more than 30% compared to high-temperature steam curing, while significantly improving the durability and heavy metal curing performance of the material.

[0113] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-performance concrete industrial solid waste admixture containing converter steel slag-polishing slag, characterized in that, Including the following parts by weight of raw materials: 280-350 parts of modified converter steel slag; 100-140 parts of modified polishing residue; 70-90 parts of electrolytic manganese slag; 90-110 parts of low-calcium high-iron cement clinker; 40-60 parts of desulfurized gypsum; 10-30 parts of nano-silica; 20-40 parts of steel slag-based composite activator.

2. The ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to claim 1, characterized in that, Including the following parts by weight of raw materials: 300-340 parts of modified converter steel slag; 110-130 parts of modified polishing residue; 75-85 parts of electrolytic manganese slag; 90-105 parts of low-calcium high-iron cement clinker; 45-55 parts of desulfurized gypsum; 15-25 parts of nano-silica; 25-35 parts of steel slag-based composite activator.

3. The ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to claim 1, characterized in that, Including the following parts by weight of raw materials: 320 parts of modified converter steel slag; 120 parts of modified polishing residue; 80 parts of electrolytic manganese slag; 100 parts of low-calcium high-iron cement clinker; 50 parts of desulfurized gypsum; 20 parts of nano-silica; 30 parts of steel slag-based composite activator.

4. A high-performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to any one of claims 1-3, characterized in that: The modified converter slag is modified converter slag that has undergone ultrasonic-plasma synergistic treatment.

5. A high-performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to any one of claims 1-3, characterized in that: The modified polishing slag is modified polishing slag that has undergone microwave-ball milling combined treatment.

6. A high-performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to any one of claims 1-3, characterized in that: The preparation method of the steel slag-based composite activator is as follows: take converter steel slag and obtain steel slag powder by magnetic separation, grinding and calcination. Mix the steel slag powder with potassium silicate and aluminum sulfate, and obtain the steel slag-based composite activator by stirring and crushing.

7. The ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to claim 6, characterized in that: The mass ratio of the steel slag powder, potassium silicate, and aluminum sulfate is 4:3:1-2.

8. A method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of modified converter steel slag: Modified converter steel slag is obtained by magnetic separation to remove iron and crushing, followed by ultrasonic-plasma synergistic treatment under N2 protection. S2. Preparation of modified polishing slag: After the polishing slag is screened to remove impurities and crushed, it is subjected to microwave treatment and ball milling in sequence to obtain modified polishing slag. S3, airflow-stage coupled two-stage ball mill: Primary ball milling: Modified converter steel slag, modified polishing slag, electrolytic manganese slag, and desulfurized gypsum are added to a ball mill and ground to obtain primary powder. Air classifier: The primary powder is fed into the air classifier, and the cutting particle size is set to 10μm to remove coarse particles; Secondary ball milling: Low-calcium high-iron cement clinker, nano-silica, and steel slag-based composite activator are added to the classified powder, and then ground to obtain the final powder; S4. Microwave-assisted carbonization treatment: Place the final powder in a microwave curing chamber, first microwave curing at 50℃ (power 800W) for 4 hours, then introduce 25% CO2 gas for carbonization curing for 10 hours (microwave power 300W continuously assisted), and after cooling to room temperature, it becomes industrial solid waste admixture.

9. The method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to claim 8, characterized in that: The operating parameters of the air classifier in step S3 are: air volume 15-20 m³ / h, classifier speed 3000-3500 r / min, and feed rate 50-60 kg / h.

10. The method for preparing an ultra-high performance concrete industrial solid waste admixture containing converter steel slag-polishing slag according to claim 8, characterized in that: In step S4, the humidity of the microwave-assisted carbonization process is controlled at 90%-95%, and the CO2 gas flow rate is 2-3 L / min.

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