A steel slag clinker 425 cement and a method for preparing the same

Abstract

The application discloses a kind of steel slag clinker 425 cement and preparation method thereof, it is related to new cement product technical field.The preparation method includes the following steps: steel slag and glass powder are mixed with 100:25-30 mass ratio after roller compaction and grinding, and low-temperature calcination is carried out, to obtain the steel slag clinker 425 cement.The application solves the core technical bottleneck that solid waste such as steel slag cannot be used as 100% raw material for producing cement products, significantly reduces the content of free calcium oxide and free magnesium oxide of steel slag, and obtains high-performance steel slag clinker 425 cement.The application plays a role of energy saving and emission reduction, reduces carbon emissions, and protects the environment, and realizes 100% resource utilization of solid waste.The steel slag clinker 425 cement product of the application has the advantages of strong adaptability and stable performance, and becomes an innovative technology for green and low-carbon transformation of the cement and steel industries.

Description

Technical Field

[0001] This invention relates to the field of new cement product technology, and in particular to a steel slag clinker 425 cement and its preparation method. Background Technology

[0002] Global steel production is approximately 1.9 billion tons annually, generating about 400 million tons of industrial solid waste, steel slag. However, the current resource utilization rate of steel slag is less than 26%. Large quantities of unused steel slag require land for dumping, wasting land resources and causing environmental problems such as water pollution. Steel slag, rich in minerals such as calcium, iron, and magnesium, has the potential to be used as a raw material for cement-based low-carbon materials, making it a highly valuable solid waste resource. However, the free calcium oxide and free magnesium oxide in steel slag easily expand in volume during hydration, and its low activity severely limits its large-scale application in the building materials industry. Currently, existing technologies still face many insurmountable challenges, hindering the large-scale, high-value utilization of steel slag. For example, while traditional carbonation processes can solidify free calcium oxide into calcium carbonate, the resulting product has low crystallinity and solubility, making it difficult to react with C3A in cement. This hinders further hydration of internal minerals, resulting in insufficient improvement in the activity of the steel slag. This restricts the high-value utilization of steel slag and affects carbon sequestration efficiency. Furthermore, methods using additives to modify steel slag suffer from high energy consumption and poor product stability. Existing related treatment technologies, such as wind-driven carbonation of steel slag, alkali-activated steel slag and slag electrolyte, co-treatment of steel slag and combustion slag, composite treatment of steel slag with cement and fly ash, mixed treatment of steel slag with fly ash and phosphogypsum, sodium carbonate recycling of steel slag for CO2 mineralization, porous biochar for regulating the morphology of steel slag carbonation products, steel slag with carbonation accelerator (sodium tripolyphosphate) and CO2 mineralization, and carbonation treatment of steel slag with calcium carbide slag, have all failed to overcome the technical bottlenecks in steel slag utilization. These technologies have a steel slag utilization rate of only about 20%, which is not only energy-intensive and complex, but also requires a large amount of acid and alkali reagents, which not only increases material costs, but may also cause new environmental pollution, making it difficult to achieve large-scale industrial application of steel slag. Summary of the Invention

[0003] The purpose of this invention is to provide a steel slag clinker 425 cement and its preparation method to solve the aforementioned problems existing in the prior art. The steel slag clinker 425 cement of this invention uses 100% solid waste as raw material, obtained by mixing and roller-pressing steel slag and glass powder, followed by low-temperature calcination, and then ball-milling to a certain specific surface area. This invention not only solves the problem that solid waste cannot be used as a 100% raw material (i.e., without adding cement clinker or other materials) for cement production, but also solves the problem of high free calcium oxide and free magnesium oxide content in steel slag, stimulating the potential hydraulic properties of steel slag, solving the problem of insufficient active cementitious properties of steel slag, and addressing the safety issue of volume expansion, thus ensuring the safety and durability of the steel slag clinker 425 cement product for use in construction projects.

[0004] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of the present invention is a method for preparing steel slag clinker 425 cement, comprising the following steps: mixing steel slag and glass powder at a mass ratio of 100:25-30, roller pressing and grinding, and then calcining at low temperature to obtain the steel slag clinker 425 cement.

[0005] The technical principle of this invention is as follows: This invention, based on the resource utilization of solid waste and the control of the microstructure of mineral materials, involves mixing and carbonizing waste steel slag and waste glass powder (i.e., low-temperature roasting). This causes the mineral phases in the steel slag and glass powder to react and form new mineral phases, thereby mineralizing and dissolving the free calcium oxide and free magnesium oxide in the steel slag. Through the mixing and carbonization of the amorphous SiO2 and Al2O3 mineral phases in the glass powder with the mineral phases in the steel slag, a completely new chemical composition and mineral phase arrangement of steel slag clinker 425 cement is formed. On this basis, the activation effect of physical roller pressing and grinding is superimposed to construct a new particle composition structure of the mixture. Through the low-temperature roasting hydration reaction, lattice distortion is induced in the steel slag clinker 425 cement, achieving autonomous decomposition of the steel slag and glass powder. This significantly reduces the free calcium oxide content in the steel slag clinker 425 cement to 0.91-1.01 wt%, the free magnesium oxide content to 2.91-3.02%, and the expansion rate to 0.36%. The following ensures the product fully complies with the technical requirements stipulated in the national cement standards. Under the synergistic effect of steel slag and glass powder, the steel slag first hydrates under the activation of the glass powder. The C2S and C3S hydration releases Ca(OH)2, which, under its activation, causes a small amount of glassy phase structure to mineralize and disintegrate. Silicon oxide and aluminum oxide ion clusters dissolve and react with Ca(OH)2 to form CSH gel and hydrated calcium silicate gel. Meanwhile, under the action of hydrated SO3, the steel slag and glass powder undergo a hydrated calcium aluminate reaction, generating not only ettringite but also further CSH gel. This rapidly forms the network skeleton structure of steel slag clinker 425 cement. The CSH gel fills the voids in the ettringite skeleton, making the structure more compact. This facilitates the carbonization and dissolution of free calcium oxide and free magnesium oxide in the steel slag clinker 425 cement and improves the product's strength development level. The low-temperature calcined mixture is ball-milled to prepare a product with a specific surface area (430±30m²). 2 The steel slag clinker 425 cement product ( / kg) can optimize particle size distribution and further enhance cementitious activity. It effectively solves the problem that steel slag, due to its high content of free calcium oxide and free magnesium oxide, easily causes structural cracking when it hydrates and expands upon contact with water. It breaks through the technical bottleneck that waste steel slag and glass powder cannot be used 100% to prepare steel slag clinker 425 cement, significantly improving the utilization rate of solid waste resources to 100% and reducing carbon emissions by about 86%. It can serve as a core technology for the green and low-carbon transformation of the cement and steel industries.

[0006] Furthermore, the raw materials for the steel slag clinker 425 cement are only steel slag and glass powder.

[0007] Furthermore, the mixing roller milling specifically involves roller milling to a particle size of 0.5-10 mm.

[0008] Furthermore, the low-temperature calcination temperature is 450-550℃.

[0009] Furthermore, the low-temperature roasting specifically refers to cyclic low-temperature roasting.

[0010] Furthermore, the free calcium oxide content in the steel slag is 4.81-7.31 wt%, and the free magnesium oxide content is 6.51-7.62%.

[0011] Furthermore, the process after low-temperature calcination includes ball milling to a specific surface area of ​​430±30 m². 2 / kg steps.

[0012] The second technical solution of the present invention: a steel slag clinker 425 cement prepared by the above-described method.

[0013] The relevant quality indicators for 425 cement are as follows: Specific surface area is 430±30m² 2 / kg, tested according to GB / T8074; Sulfur trioxide content ≤3.5%, tested according to GB / T176; The free magnesium oxide content is ≤5.0%, and the test shall be conducted in accordance with GB / T176; The free calcium oxide content is ≤1.5wt%, and the test shall be conducted in accordance with GB / T176; Chloride ion content ≤0.06wt%, tested according to GB / T176; Stability (expansion rate) ≤ 5.0 mm, tested according to GB / T1346; The standard consistency water consumption is ≤28wt%, and the test shall be carried out in accordance with GB / T1346; Setting time: initial setting time ≥ 60 min, final setting time ≤ 300 min, tested according to GB / T1346; Strength grades: 3-day flexural strength ≥ 4.5 MPa, 28-day flexural strength ≥ 6.5 MPa, 3-day compressive strength ≥ 20.0 MPa, 28-day compressive strength ≥ 42.5 MPa, tested according to GB / 17671 (cement mortar specimen preparation conditions include: cement-sand ratio of 1:3, water-cement ratio of 0.5).

[0014] The specific quality technical indicators that the steel slag clinker 425 cement of the present invention can achieve are as follows: Specific surface area is 430±30m² 2 / kg; sulfur trioxide content is 2.50-2.52wt%; free magnesium oxide content is 2.91-3.02wt%; free calcium oxide content is 0.91-1.01wt%; chloride ion content is 0.018-0.021%; stability is qualified, expansion rate is 1.0-2.6mm; setting time: initial setting time is 90-96min, final setting time is 165-175min; standard consistency water consumption is 25.8-26.1wt%; strength grade: 3-day and 28-day flexural and compressive strengths are 5.1-5.4MPa, 23.1-25.0MPa, 7.1-7.8MPa, and 48.0-49.5MPa, respectively.

[0015] This invention uses steel slag and glass powder as raw materials. Through mixing and roller pressing and grinding into balls (particle size 0.5-10mm) and low-temperature calcination at 450-550℃, a highly efficient hydration reaction of steel slag and glass powder mineralization is achieved. At the same time, it promotes the directional carbonization and dissolution of free calcium oxide and free magnesium oxide in steel slag, and finally obtains steel slag clinker 425 cement. Its carbonization efficiency is about 86% higher than that of traditional processes, completely breaking away from the technical limitations of traditional mineral carbonization. This invention innovatively proposes a technical solution for preparing cement products using steel slag composite glass powder as 100% raw material. Through the above-mentioned mixing and roller pressing and low-temperature calcination process, combined with ball milling after low-temperature calcination, the steel slag clinker 425 cement product is finally obtained.

[0016] The present invention discloses the following technical effects: 1. This invention prepares steel slag clinker 425 cement by mixing, rolling, grinding and calcining solid waste steel slag and glass powder using only solid waste steel slag and glass powder. It can be widely used in construction projects and significantly improves the problem of high free calcium oxide and free magnesium oxide content in steel slag, which easily undergoes hydration reaction when exposed to water, causing volume expansion and thus easily leading to structural cracking of buildings.

[0017] 2. This invention effectively solves the problem of high free calcium oxide and free magnesium oxide content in steel slag. The free calcium oxide and free magnesium oxide in steel slag, together with the amorphous SiO2, Al2O3, glass phase and other major mineral phases in waste glass powder, undergo mineralization, decomposition and carbonization, which eliminates the volume expansion caused by the high content of free calcium oxide and free magnesium oxide in steel slag. This significantly reduces the content of free calcium oxide and free magnesium oxide in steel slag clinker 425 cement and significantly reduces the expansion rate, so that the steel slag clinker 425 cement product fully meets the technical requirements stipulated in the national cement standards.

[0018] 3. This invention pioneers a technical approach for carbon mineralization using steel slag and glass powder as raw materials by mixing different mineral phases. By inducing lattice distortion in steel slag clinker 425 cement, the mineral phases of steel slag and glass powder are autonomously decomposed, thereby solving the problem of uncoordinated binary reactions in traditional steel slag and glass powder used alone (working alone) or in multi-component composite systems.

[0019] 4. The invention clarifies the core activation mechanism: steel slag and glass powder are mixed and rolled, and then calcined at low temperature to hydrate and transform into highly active C2S and C3S. The optimized particle structure can accelerate hydration, promote the dissolution of silicon oxide and aluminum oxide ion groups and react with Ca(OH)2 to generate CSH gel and hydrated calcium silicate gel, thereby achieving a synergistic improvement in early strength (3 days) and later strength (28 days).

[0020] 5. The optimal mixing ratio of steel slag and glass powder at a mass ratio of 100:30 is the optimal mixing ratio of the present invention. The 3-day and 28-day compressive strength of the obtained steel slag clinker 425 cement is significantly improved, carbon emissions are reduced, and the resource utilization level of solid waste reaches 100%.

[0021] 6. This invention has outstanding application value. The preparation method does not require modification of existing production lines. It can realize the resource utilization of steel slag and glass powder mixture, and significantly reduce the carbon emissions of steel slag clinker 425 cement products. It can significantly reduce production costs, solve environmental pollution problems, provide low-carbon new products for the construction industry, and become the core innovative technology for the green and low-carbon transformation of the cement and steel industries. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0028] Unless otherwise specified, the room temperature mentioned in the following embodiments and comparative examples of the present invention refers to 20-30°C.

[0029] Unless otherwise specified, all raw materials used in the following embodiments and comparative examples of this invention are commercially available products. Among them, the steel slag comes from Huai'an Iron and Steel Plant, which is an industrial waste generated during the steel production process using ore. Its main chemical components are mineral phases such as CaO, Al2O3, Fe2O3, free calcium oxide, and free magnesium oxide, with the content of free calcium oxide being 4.81-7.31 wt% and the content of free magnesium oxide being 6.51-7.62 wt%. The waste glass powder comes from automobile manufacturing enterprises in Jiangsu Province. It is an industrial waste generated during the grinding and discharge process in the manufacture of automobile glass. The chemical composition of the glass powder is mainly SiO2, Al2O3, etc., and its mineral phases mainly include quartz, aluminate, etc., as well as a small amount of glass phase.

[0030] Example 1 A type of 425 cement made from steel slag clinker is prepared by the following steps: Weigh steel slag and glass powder at a mass ratio of 100:25 (i.e., 100 parts by mass of steel slag + 25 parts by mass of glass powder), mix and grind them in a roller press (feeding and circulating roller pressing grinding are carried out on a scale of continuous processing of 6 tons of material), and grind them to a particle size of 0.5-10 mm. Then, the roller-pressed mixture is calcined at a low temperature of 450℃. After calcination, the mixture is ball-milled separately without adding any cement clinker or other materials to a specific surface area of ​​430±30 m². 2 / kg, to obtain steel slag clinker 425 cement product. Product quality was tested according to the following standards: specific surface area according to GB / T8074, sulfur trioxide content according to GB / T176, free magnesium oxide content according to GB / T176, free calcium oxide content according to GB / T176, chloride ion content according to GB / T176, standard consistency water requirement according to GB / T1346, setting time according to GB / T1346, stability according to GB / T1346, 3-day and 28-day strength according to GB / T17671. In the strength test, when preparing the cement mortar specimens for testing, the mass ratio of steel slag clinker 425 cement product to standard sand was 1:3 (i.e., the cement-sand ratio was 1:3), and the ratio of mixing water to the mass of steel slag clinker 425 cement product was 0.5 (i.e., the water-cement ratio was 0.5). Specific test results are shown in Table 1.

[0031] Table 1 As shown in Table 1, the preparation method used in this embodiment effectively reduces the content of free calcium oxide and free magnesium oxide in solid waste steel slag, thereby significantly improving the core problem of high free calcium oxide and free magnesium oxide content in steel slag, which leads to hydration reaction upon contact with water, causing volume expansion and easily resulting in structural cracking of buildings. The resulting steel slag clinker 425 cement product has significantly better quality and technical indicators than the national standard requirements, especially with a free calcium oxide content of only 1.01 wt% and a free magnesium oxide content of only 3.02 wt%, and its stability is qualified (expansion rate of 2.6 mm). Furthermore, it is particularly noteworthy that this product is prepared from 100% solid waste steel slag and glass powder as raw materials, and its 3-day and 28-day compressive strengths both meet or even exceed the national standard for ordinary silicate 425 cement produced from 100% natural raw materials. This demonstrates the core technological advantage of this invention in preparing high-performance cement from all solid waste raw materials.

[0032] Example 2 A type of 425 cement made from steel slag clinker is prepared by the following steps: Weigh steel slag and glass powder at a mass ratio of 100:28, and mix and grind them in a roller press (feeding and circulating roller pressing are carried out on a scale of continuous processing of 6 tons of material). Grind the mixture until the particle size is 0.5-10mm. Then, calcine the mixture at a low temperature of 500℃. After calcination, the mixture is then ball-milled separately without adding any cement clinker or other materials until the specific surface area is 430±30m². 2 / kg, to obtain steel slag clinker 425 cement product. Product quality was tested according to the following standards: specific surface area according to GB / T8074, sulfur trioxide content according to GB / T176, free magnesium oxide content according to GB / T176, free calcium oxide content according to GB / T176, chloride ion content according to GB / T176, standard consistency water requirement according to GB / T1346, setting time according to GB / T1346, stability according to GB / T1346, 3-day and 28-day strength according to GB / T17671. In the strength test, when preparing the cement mortar specimens for testing, the mass ratio of steel slag clinker 425 cement product to standard sand was 1:3 (i.e., the cement-sand ratio was 1:3), and the ratio of mixing water to the mass of steel slag clinker 425 cement product was 0.5 (i.e., the water-cement ratio was 0.5). Specific test results are shown in Table 2.

[0033] Table 2 As shown in Table 2, the 425 cement product made from steel slag clinker in this embodiment effectively reduces the content of free calcium oxide and free magnesium oxide in solid waste steel slag and glass powder, forming a particle structure that is beneficial to performance improvement. The product has a specific surface area of ​​452 m². 2 The clinker content was 2.51% sulfur trioxide, 3.01 wt% free magnesium oxide, only 0.96 wt% free calcium oxide, and 0.019 wt% chloride ion. It exhibited satisfactory stability (expansion value of 2.5 mm), an initial setting time of 93 min, a final setting time of 170 min, a standard consistency water requirement of 25.9%, and compressive strengths of 24.5 MPa and 48.6 MPa at 3 and 28 days, respectively. These results further demonstrate that the process of using steel slag and glass powder composite feedstock, and promoting mineral phase formation and carbonate decomposition through low-temperature cyclic roasting, is reasonable. This effectively induces lattice structure distortion in the clinker minerals, thereby significantly suppressing the free calcium oxide content (reducing it to 0.96 wt%) and achieving high mechanical properties (28-day compressive strength of 48.6 MPa), ensuring the stability and improvement of the performance of the steel slag clinker 425 cement product.

[0034] Example 3 A type of 425 cement made from steel slag clinker is prepared by the following steps: Weigh steel slag and glass powder at a mass ratio of 100:30, mix and grind them in a roller press (feeding and circulating roller pressing are carried out on a scale of continuous processing of 6 tons of material), and grind them to a particle size of 0.5-10mm. Then, the roller-pressed mixture is calcined at a low temperature of 550℃. After calcination, the mixture is then ball-milled separately without adding any cement clinker or other materials to a specific surface area of ​​430±30m². 2 / kg, to obtain steel slag clinker 425 cement product. Product quality was tested according to the following standards: specific surface area according to GB / T8074, sulfur trioxide content according to GB / T176, free magnesium oxide content according to GB / T176, free calcium oxide content according to GB / T176, chloride ion content according to GB / T176, standard consistency water requirement according to GB / T1346, setting time according to GB / T1346, soundness according to GB / T1346, 3-day and 28-day strength according to GB / T17671. In the strength test, when preparing the cement mortar specimens for testing, the mass ratio of steel slag clinker 425 cement product to standard sand was 1:3 (i.e., the cement-sand ratio was 1:3), and the ratio of mixing water to the mass of steel slag clinker 425 cement product was 0.5 (i.e., the water-cement ratio was 0.5). Specific test results are shown in Table 3.

[0035] Table 3 As shown in Table 3, the steel slag clinker 425 cement product prepared in this embodiment exhibits good adaptability, stable performance, and significant grinding aid and strengthening effects. Compared with existing technologies, this invention uses a roller-pressing process to activate the mineral phase by mixing steel slag and glass powder, followed by low-temperature cyclic calcination to promote the hydration reaction and convert highly active C2S and C3S, thus accelerating the hydration process of steel slag clinker 425 cement. This process promotes the dissolution of silicon oxide and aluminum oxide ion clusters, which react with Ca(OH)2 to generate CSH gel and hydrated calcium silicate gel, significantly reducing the content of free calcium oxide and free magnesium oxide in the steel slag clinker 425 cement product, achieving simultaneous improvement in early and later strength.

[0036] The process described in this embodiment effectively improves the overall technical specifications of the product: the specific surface area reaches 460m². 2 The product contains 2.50 wt% sulfur trioxide, 2.91 wt% free magnesium oxide, and free calcium oxide reduced to 0.91 wt%, with a chloride ion content of 0.018 wt%. Stability is satisfactory (expansion rate is 1.0 mm). Initial setting time is 90 min, final setting time is 165 min, and standard consistency water requirement is 25.8 wt%. The 3-day compressive strength is 25.0 MPa, and the 28-day compressive strength reaches 49.5 MPa. These data further confirm the rationality of this technical approach and the excellent performance of the product.

[0037] Comparative Example 1 A type of 425 cement made from steel slag clinker is prepared by the following steps: Weigh steel slag and glass powder at a mass ratio of 100:25, and mix and grind them in a roller press (feeding and circulating roller pressing are carried out on a scale of continuous processing of 6 tons of material). Grind the mixture until the particle size is 0.5-10mm. Then, calcine the mixture at a low temperature of 400℃. After calcination, the mixture is then ball-milled separately without adding any cement clinker or other materials until the specific surface area is 430±30m². 2 / kg, to obtain steel slag clinker 425 cement product. Product quality was tested according to the following standards: specific surface area according to GB / T8074, sulfur trioxide content according to GB / T176, free magnesium oxide content according to GB / T176, free calcium oxide content according to GB / T176, chloride ion content according to GB / T176, standard consistency water requirement according to GB / T1346, setting time according to GB / T1346, stability according to GB / T1346, 3-day and 28-day strength according to GB / T17671. In the strength test, when preparing the cement mortar specimens for testing, the mass ratio of steel slag clinker 425 cement product to standard sand was 1:3 (i.e., the cement-sand ratio was 1:3), and the ratio of mixing water to the mass of steel slag clinker 425 cement product was 0.5 (i.e., the water-cement ratio was 0.5). Specific test results are shown in Table 4.

[0038] Table 4 As shown in Table 4, the raw material ratio of the steel slag clinker 425 cement product prepared in this comparative example is the same as that in Example 1. The only difference is that the calcination temperature is reduced to 400℃. At this calcination temperature, the hydration reaction of the steel slag clinker 425 cement is incomplete, and the calcination is insufficient, thus affecting the quality performance indicators of the product. The most significantly affected component is the free calcium oxide content, which increases to 1.56wt%, becoming a non-compliant item; secondly, the stable expansion rate increases to 5.6mm (exceeding the acceptable range); at the same time, the 3-day and 28-day compressive strengths also decrease to 20.0MPa and 43.5MPa, respectively. Therefore, the optimal calcination temperature for preparing steel slag clinker 425 cement in this invention should be controlled within 500±50℃, and this temperature range is the key process core to ensure product performance.

[0039] Comparative Example 2 A type of 425 cement made from steel slag clinker is prepared by the following steps: Weigh steel slag and glass powder at a mass ratio of 100:30, and mix and grind them in a roller press (feeding and circulating roller pressing are carried out on a scale of continuous processing of 6 tons of material). Grind the mixture until the particle size is 0.5-10mm. Then, calcine the mixture at a low temperature of 600℃. After calcination, the mixture is then ball-milled separately without adding any cement clinker or other materials until the specific surface area is 430±30m². 2 / kg, to obtain steel slag clinker 425 cement product. Product quality was tested according to the following standards: specific surface area according to GB / T8074, sulfur trioxide content according to GB / T176, free magnesium oxide content according to GB / T176, free calcium oxide content according to GB / T176, chloride ion content according to GB / T176, standard consistency water requirement according to GB / T1346, setting time according to GB / T1346, stability according to GB / T1346, 3-day and 28-day strength according to GB / T17671. In the strength test, when preparing the cement mortar specimens for testing, the mass ratio of steel slag clinker 425 cement product to standard sand was 1:3 (i.e., the cement-sand ratio was 1:3), and the ratio of mixing water to the mass of steel slag clinker 425 cement product was 0.5 (i.e., the water-cement ratio was 0.5). Specific test results are shown in Table 5.

[0040] Table 5 As shown in Table 5, the raw material ratio scheme of the steel slag clinker 425 cement product in this comparative example is exactly the same as that in Example 3, the only difference being that the calcination temperature is increased to 600℃. Experimental results show that the various quality and technical indicators of the product obtained under these conditions are basically consistent with the data in Example 3 (see Table 3). This indicates that when the calcination temperature exceeds 550℃, the product performance does not improve significantly further, but instead increases unnecessary energy consumption and production costs. Therefore, the optimal calcination temperature for the steel slag clinker 425 cement of this invention is 500±50℃.

[0041] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing 425 cement from steel slag clinker, characterized in that, Includes the following steps: Steel slag and glass powder are mixed and roller-pressed at a mass ratio of 100:25-30 and then calcined at low temperature to obtain the steel slag clinker 425 cement.

2. The method for preparing 425 cement from steel slag clinker as described in claim 1, characterized in that, The raw materials for the steel slag clinker 425 cement are only steel slag and glass powder.

3. The method for preparing 425 cement from steel slag clinker as described in claim 1, characterized in that, The mixed roller pressing and grinding specifically refers to roller pressing and grinding to a particle size of 0.5-10mm.

4. The method for preparing 425 cement from steel slag clinker as described in claim 1, characterized in that, The low-temperature roasting temperature is 450-550℃.

5. The method for preparing 425 cement from steel slag clinker as described in claim 1, characterized in that, The free calcium oxide content in the steel slag is 4.81-7.31 wt%, and the free magnesium oxide content is 6.51-7.62%.

6. The method for preparing 425 cement from steel slag clinker as described in claim 1, characterized in that, The low-temperature calcination process further includes ball milling to a specific surface area of ​​430±30m². 2 / kg steps.

7. A steel slag clinker 425 cement prepared by the method of preparing steel slag clinker 425 cement as described in any one of claims 1-6.

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