A method for preparing a high-activity mineral admixture with good stability by composite activation of iron tailings and steel slag

Abstract

The application discloses a method for preparing high-activity mineral admixture with good stability from composite activated iron tailings and steel slag, and relates to the technical field of resource utilization of bulk industrial solid waste. The method comprises the following steps: mixing iron tailings, steel slag, auxiliary siliceous material and auxiliary calcareous material to obtain a mixture; mixing the mixture with water and then performing hydrothermal reaction to obtain a hydrothermal reaction product; and performing calcination treatment on the hydrothermal reaction product to obtain the high-activity mineral admixture with good stability. The method uses iron tailings and steel slag as main raw materials, performs hydrothermal reaction on the iron tailings and the steel slag to digest free oxides in the steel slag, and then performs calcination treatment to obtain the high-activity mineral admixture. The method can solve the problem of poor stability of the steel slag and stimulate the activity of the iron tailings and the steel slag. The method can reduce resource consumption, save production cost, reduce CO2 emission, and achieve the purpose of solving the environmental pollution problem and creating economic benefits.

Description

Technical Field

[0001] This invention relates to the field of resource utilization technology for bulk industrial solid waste, and in particular to a method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag. Background Technology

[0002] Iron tailings emissions and stockpiles are enormous. The large-scale stockpiling of iron tailings not only requires significant land use and consumes substantial human, material, and financial resources for management, but some iron tailings also contain heavy metals and other harmful substances that can pollute groundwater resources. Therefore, improving the comprehensive utilization rate of iron tailings and developing green and environmentally friendly utilization models is of great significance. Due to rising iron concentrate prices and advancements in mineral processing technology, the grade of beneficiated iron ore has been continuously decreasing, leading to an increase in the amount of fine-grained iron tailings. Iron tailings with a particle size of less than 0.6 mm account for over 90%, making them unsuitable as aggregates for use in ready-mixed concrete. The main components of iron tailings are similar to cementitious materials, but are inert components. Without appropriate modification, they can only function as micro-aggregate fillers, acting as inactive materials in cement concrete.

[0003] Steel slag is a bulk industrial waste. Large-scale stockpiling of steel slag not only occupies valuable land resources but also pollutes the atmosphere and water environment, resulting in negative effects on both resource utilization and environmental protection. The silicate minerals in steel slag have complete crystallization, with coarse grains and a dense structure. Their hydration rate is much slower than that of silicate cement, and their early hydration strength is very low. The large amounts of free calcium oxide (ƒ-CaO) and free magnesium oxide (ƒ-MgO) in steel slag cause serious stability problems. Building structures using steel slag admixtures frequently exhibit significant expansion and cracking a few years after construction. Therefore, the efficient, safe, and stable use of steel slag has become a bottleneck for the sustainable development of the steel industry. The development and application of clean and effective treatment processes and large-scale steel slag product technologies are of great significance for promoting the circular economy development of the steel industry.

[0004] In recent years, mineral admixtures such as fly ash and silica fume have been used and consumed extensively, making high-quality admixtures increasingly scarce and driving up prices. If highly active mineral admixtures could be prepared using iron tailings and steel slag, high-value utilization of these materials would be achieved. This would not only replace high-quality admixtures, significantly reducing costs, but also lower carbon emissions, mitigate environmental impact, alleviate the pressure of disposing of iron tailings and steel slag stockpiles, and solve potential pollution problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, thereby solving the aforementioned problems in the prior art. This invention uses iron tailings and steel slag as main raw materials, and obtains the mineral admixture through hydrothermal reaction and calcination. Specifically, by controlling the mass ratio of siliceous to calcareous components, the solid-liquid mass ratio, the hydrothermal reaction conditions, and the calcination conditions, free oxides in the steel slag are effectively eliminated, and the activity of the iron tailings and steel slag is activated, thus preparing a highly stable and active mineral admixture.

[0006] 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 a highly active mineral admixture with good stability from composite activated iron tailings and steel slag, comprising the following steps: Iron tailings, steel slag, auxiliary siliceous materials and auxiliary calcareous materials are mixed to obtain a mixture; The mixture is mixed with water and then subjected to a hydrothermal reaction to obtain the hydrothermal reaction product. The hydrothermal reaction products are calcined to obtain the highly active mineral admixture with good stability.

[0007] This invention introduces a composite activation method that co-processes iron tailings and steel slag. The siliceous component is mainly from iron tailings, and the calcareous component is mainly from steel slag. Through a hydrothermal reaction, free oxides in the steel slag are converted into other hydration products, synthesizing a composite system containing hydrated calcium silicate (CSH), tobermorite (C5S6H5), calcium silicate (C6S6H), calcium aluminate hydrate (CAH), calcium aluminosilicate hydrate (CASH), and magnesium silicate hydrate (MSH). This composite system is then calcined and dehydrated to prepare a highly active mineral admixture with good stability. This method not only eliminates free oxides in steel slag, preventing instability issues, but also improves the activation effect of iron tailings and steel slag. This method can reduce resource consumption, save production costs, and reduce CO2 emissions, achieving the goal of solving environmental pollution problems while creating economic benefits.

[0008] Furthermore, the SiO2 content in the iron tailings is higher than 40 wt%.

[0009] Furthermore, the CaO content in the steel slag is higher than 30 wt%.

[0010] Furthermore, the auxiliary siliceous material includes one or more of kaolin, coal gangue, and nickel slag.

[0011] Furthermore, the auxiliary calcium material includes one or more of slag, carbide slag, and desulfurization ash.

[0012] Furthermore, the mass ratio of the iron tailings, steel slag, auxiliary siliceous material and auxiliary calcareous material is (1~5):1:(0~0.25):(0~0.25).

[0013] Furthermore, the mass ratio of the mixture to water is 1:(1~20).

[0014] Furthermore, the hydrothermal reaction is carried out at a temperature of 80~200℃ for a time of 1~8h.

[0015] Furthermore, the calcination treatment is carried out at a temperature of 400~900℃ for a time of 0.5~8h.

[0016] Furthermore, the iron tailings, steel slag, auxiliary silica materials, and auxiliary calcium materials are all ground materials. That is, the iron tailings, steel slag, auxiliary silica materials, and auxiliary calcium materials are first ground separately, and then the ground iron tailings, steel slag, auxiliary silica materials, and auxiliary calcium materials are mixed together.

[0017] Furthermore, the grinding specifically refers to grinding to a fineness of ≤1wt% on an 80μm sieve.

[0018] Preferably, the method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag includes the following more specific steps: Step 1: Grind the iron tailings, steel slag, auxiliary siliceous materials, and auxiliary calcareous materials separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, auxiliary siliceous materials, and auxiliary calcareous materials in a mass ratio of (1~5):1:(0~0.25):(0~0.25) to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, and the mass ratio of the mixture to tap water is 1:(1~20). Stir well, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 80~200℃ and the holding time to 1~8h. After the hydrothermal reaction is completed, take out the material in the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step 6: Control the constant temperature of calcination treatment to 400~900℃ and the constant temperature time to 0.5~8h. After calcination treatment, take out the material in the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0019] The second technical solution of the present invention: A highly active mineral admixture with good stability prepared by the method described above for preparing a composite activated iron tailings and steel slag.

[0020] The specific principles and advantages of this invention are as follows: The hydrothermal reaction is carried out in a specially designed, sealed, high-pressure reactor. The reaction temperature for hydrothermal treatment of solid waste is generally between 100 and 250°C, classifying it as a subcritical hydrothermal reaction (temperature <374.20°C, pressure <21.58 MPa). Under subcritical hydrothermal synthesis conditions, the reaction occurs at the molecular level, thus hydrothermal reactions can replace certain high-temperature solid-phase reactions. Furthermore, because the homogeneous and heterogeneous nucleation mechanisms of hydrothermal reactions differ from the diffusion mechanisms of solid-phase reactions, it is possible to create new substances that cannot be prepared by other reaction methods. The hydrothermal synthesis of silicon-calcium solid waste is a medium-temperature hydrothermal synthesis, with a reaction temperature more than 80% lower than that of sintering high-temperature solid-phase reactions.

[0021] In a hydrothermal environment, the Ca content of steel slag and other calcareous raw materials... 2+ Diffusion into the solution creates an alkaline environment rich in Ca(OH)₂. Under the influence of high temperature, high pressure, and an alkaline environment, some silicon and aluminum components in the iron tailings and other siliceous raw materials are activated. These silicon and aluminum components react with Ca(OH)₂ to generate hydration products such as CSH, C5S6H₅, C6S6H, CAH, and CASH. In steel slag, ƒ-CaO preferentially reacts with SiO₂ to generate CSH; ƒ-MgO reacts with the remaining SiO₂ to generate MSH; when SiO₂ is depleted, the OH⁻ from the decomposition of water molecules attached to the ƒ-MgO surface reacts with the Mg⁺ released by the ƒ-MgO. 2+ The materials combine to form Mg(OH)₂. Through the synergistic effect between the materials, the free oxides in the steel slag are transformed into other hydration products under hydrothermal conditions, solving its poor stability problem. Compared with traditional methods of activating iron tailings, this method has lower energy consumption, lower raw material costs, faster reaction rates, and generates more hydration products.

[0022] Hydration products such as CSH, CAH, CASH, and MSH generated under hydrothermal conditions, after calcination and dehydration, form anhydrous calcium silicate, calcium aluminate, calcium aluminosilicate, and magnesium silicate, which are substances with cementing activity. C5S6H5, after dehydration, forms wollastonite and amorphous silica. The amorphous silica further reacts with CaO to generate cementing Ca2SiO4. The rehydration properties of these dehydrated phases are utilized to prepare highly active mineral admixtures with good stability. Compared to cement firing conditions, this calcination and dehydration condition has a lower temperature and shorter time, which can significantly reduce energy consumption.

[0023] The present invention discloses the following technical effects: This invention uses iron tailings and steel slag as main raw materials, and obtains a highly active mineral admixture with good stability through hydrothermal reaction and calcination. The method of this invention can solve the problem of poor stability of steel slag and activate the iron tailings and steel slag.

[0024] The mineral admixture prepared using the method of this invention, according to GB / T 38216.3-2023 "Determination of Free Calcium Oxide Content in Steel Slag - EDTA Titration and Thermogravimetric Analysis" and YB / T 140-2009 "Chemical Analysis Methods for Steel Slag", shows low contents of both free calcium oxide and free magnesium oxide, indicating good stability. According to GB / T 12957-2005 "Test Method for Activity of Industrial Waste Residue Used in Cement Blends", its compressive strength is not less than 80% of that of ordinary Portland cement after 28 days, indicating high activity. This highly active mineral admixture with good stability fully utilizes solid waste and incorporates a large amount of iron tailings, realizing the secondary resource utilization of solid waste and providing a new approach for the large-scale utilization of iron tailings and steel slag. Detailed Implementation

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] Unless otherwise specified, the room temperature mentioned in the following embodiments, comparative examples and test examples of this invention refers to 20-30°C.

[0032] Unless otherwise specified in the following embodiments, comparative examples, and test examples of this invention, the conditions shall be performed under conventional conditions or conditions recommended by the manufacturer.

[0033] Unless otherwise specified, all raw materials and instruments used in the following embodiments, comparative examples, and test examples of this invention are commercially available; the specific details of the raw materials are as follows: Iron tailings: The main chemical components by mass are SiO2 52.61%, Al2O3 14.39%, CaO 5.22%, Fe2O3 10.68%, and MgO 7.36%; Steel slag: Its main chemical components by mass content are SiO2 16.63%, Al2O3 6.84%, CaO 47.13%, Fe2O3 13.26%, and MgO 5.21%; Tap water; Cement: Ordinary Portland cement (PO 52.5), commercially available; Auxiliary siliceous materials: one or more of kaolin, coal gangue, and nickel slag, commercially available; Auxiliary calcium materials: one or more of slag, carbide slag and desulfurization ash, commercially available.

[0034] Example 1 A method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, comprising the following steps: Step 1: Grind the iron tailings and steel slag separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings and steel slag at a mass ratio of 5:1 to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:1, stir evenly, seal the hydrothermal reactor and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 80℃ and the holding time to 8h. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step 6: Control the constant temperature of the calcination treatment to 400℃ and the constant temperature time to 8h. After the calcination treatment, take out the material in the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0035] Example 2 A method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, comprising the following steps: Step 1: Grind the iron tailings, steel slag, and auxiliary calcium materials (slag) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, and auxiliary calcium materials (slag) at a mass ratio of 2:1:0.2 to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:5, stir evenly, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 100℃ and the holding time to 6 hours. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step Six: Control the constant temperature of the calcination treatment to 500℃ and the constant temperature time to 6h. After the calcination treatment, take out the material from the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0036] Example 3 A method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, comprising the following steps: Step 1: Grind the iron tailings, steel slag, and auxiliary siliceous material (kaolin) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, and auxiliary siliceous material (kaolin) at a mass ratio of 1:1:0.2 to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:10, stir evenly, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 140℃ and the holding time to 4 hours. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step 6: Control the constant temperature of the calcination treatment to 600℃ and the constant temperature time to 4h. After the calcination treatment, take out the material in the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0037] Example 4 A method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, comprising the following steps: Step 1: Grind the iron tailings, steel slag, auxiliary siliceous materials (coal gangue), and auxiliary calcareous materials (desulfurization ash) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, auxiliary siliceous material (coal gangue), and auxiliary calcareous material (desulfurization ash) in a mass ratio of 1:1:0.25:0.25 to obtain a mixture. Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:20, stir evenly, seal the hydrothermal reactor and carry out the hydrothermal reaction; Step 4: Control the hydrothermal reaction temperature to 180℃ and the holding time to 6 hours. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step Six: Control the constant temperature of the calcination treatment to 900℃ and the constant temperature time to 0.5h. After the calcination treatment, take out the material from the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0038] Example 5 A method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag, comprising the following steps: Step 1: Grind the iron tailings, steel slag, auxiliary siliceous materials (coal gangue and nickel slag), and auxiliary calcareous materials (carbide slag and desulfurization ash) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, coal gangue, nickel slag, carbide slag, and desulfurization ash in a mass ratio of 3:1:0.05:0.05:0.05:0.05 to obtain a mixture. Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:15, stir evenly, seal the hydrothermal reactor and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 200℃ and the holding time to 1 hour. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 5: The hydrothermal reaction product obtained in Step 4 is placed into a crucible and then placed in a high-temperature calcining furnace for calcination. Step 6: Control the constant temperature of the calcination treatment to 800℃ and the constant temperature time to 1 hour. After the calcination treatment, take out the material from the crucible and let it cool naturally to obtain a highly active mineral admixture with good stability.

[0039] Comparative Example 1 Step 1: Grind the iron tailings, steel slag, auxiliary siliceous materials (coal gangue and nickel slag), and auxiliary calcareous materials (carbide slag) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, coal gangue, nickel slag and carbide slag in a mass ratio of 1:1:0.1:0.1:0.2 to obtain a mixture as a mineral admixture.

[0040] Comparative Example 2 Step 1: Grind the iron tailings, steel slag, and auxiliary calcium materials (carbide slag and desulfurization ash) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, carbide slag, and desulfurization ash in a mass ratio of 4:1:0.1:0.1 to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:10, stir evenly, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 180℃ and the constant temperature time to 8 hours. After the hydrothermal reaction is completed, take out the material from the hydrothermal reactor to obtain the hydrothermal reaction product, and dry it as a mineral admixture.

[0041] Comparative Example 3 Step 1: Grind the iron tailings, steel slag, auxiliary siliceous materials (kaolin, coal gangue and nickel slag), and auxiliary calcareous materials (desulfurization ash) separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings, steel slag, kaolin, coal gangue, nickel slag, and desulfurization ash in a mass ratio of 2:1:0.05:0.05:0.05:0.05 to obtain a mixture. Step 3: Load the mixture obtained in Step 2 into a crucible and place it in a high-temperature calcining furnace for calcination. Step 4: Control the constant temperature of the calcination treatment to 800℃ and the constant temperature time to 6h. After the calcination treatment, take out the material in the crucible and let it cool naturally to obtain the mineral admixture.

[0042] Comparative Example 4 Step 1: Grind the iron tailings and steel slag separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings and steel slag at a mass ratio of 5:1 to obtain a mixture as a mineral admixture.

[0043] Comparative Example 5 Step 1: Grind the iron tailings and steel slag separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings and steel slag at a mass ratio of 5:1 to obtain a mixture; Step 3: Place the mixture obtained in Step 2 into a hydrothermal reactor, add tap water, the mass ratio of the mixture to tap water is 1:1, stir evenly, seal the hydrothermal reactor and carry out the hydrothermal reaction. Step 4: Control the hydrothermal reaction temperature to 80℃ and the constant temperature time to 8h. After the hydrothermal reaction is completed, take out the material from the hydrothermal reactor to obtain the hydrothermal reaction product, and dry it as a mineral admixture.

[0044] Comparative Example 6 Step 1: Grind the iron tailings and steel slag separately to a fineness of ≤1wt% on an 80μm sieve; Step 2: Mix the ground iron tailings and steel slag at a mass ratio of 5:1 to obtain a mixture; Step 3: Load the mixture obtained in Step 2 into a crucible and place it in a high-temperature calcining furnace for calcination. Step 4: Control the constant temperature of the calcination treatment to 400℃ and the constant temperature time to 8h. After the calcination treatment, take out the material from the crucible and let it cool naturally to obtain the mineral admixture.

[0045] Comparative Example 7 Step 1: Grind the iron tailings to a fineness of ≤1wt% on an 80μm sieve; Step 2: Place the ground iron tailings into a hydrothermal reactor, add tap water, with a mass ratio of iron tailings to tap water of 1:1, stir well, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 3: Control the hydrothermal reaction temperature to 80℃ and the holding time to 8h. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 4: The hydrothermal reaction product obtained in Step 3 is loaded into a crucible and placed in a high-temperature calcining furnace for calcination. Step 5: Control the constant temperature of the calcination treatment to 400℃ and the constant temperature time to 8h. After the calcination treatment, take out the material in the crucible and let it cool naturally to obtain the mineral admixture.

[0046] Comparative Example 8 Step 1: Grind the steel slag to a fineness of ≤1wt% on an 80μm sieve; Step 2: Place the ground steel slag into a hydrothermal reactor, add tap water, with a mass ratio of steel slag to tap water of 1:1, stir well, seal the hydrothermal reactor, and carry out the hydrothermal reaction. Step 3: Control the hydrothermal reaction temperature to 80℃ and the holding time to 8h. After the hydrothermal reaction is completed, remove the material from the hydrothermal reactor to obtain the hydrothermal reaction product. Step 4: The hydrothermal reaction product obtained in Step 3 is loaded into a crucible and placed in a high-temperature calcining furnace for calcination. Step 5: Control the constant temperature of the calcination treatment to 400℃ and the constant temperature time to 8h. After the calcination treatment, take out the material in the crucible and let it cool naturally to obtain the mineral admixture.

[0047] Comparative Example 9 The mineral admixture (activated iron tailings) prepared in Comparative Example 7 and the mineral admixture (activated steel slag) prepared in Comparative Example 8 were mixed at a mass ratio of 5:1 to form the mineral admixture sample of this comparative example.

[0048] Test Example 1 For the mineral admixtures prepared in Examples 1-5 and Comparative Examples 1-9 above, the free calcium oxide content was determined according to GB / T 38216.3-2023 "Determination of Free Calcium Oxide Content in Steel Slag - EDTA Titration and Thermogravimetric Analysis"; the free magnesium oxide content was determined according to YB / T 140-2009 "Chemical Analysis Methods for Steel Slag"; and 30 wt% of the mineral admixtures prepared in Examples 1-5 or Comparative Examples 1-9 were added to ordinary Portland cement (PO 52.5) ​​according to GB / T 12957-2005 "Test Methods for Activity of Industrial Waste Slag Used in Cement Blends". The 28-day compressive strength of the admixtures was compared with that of ordinary Portland cement (PO 52.5). The stability and activity of the mineral admixtures were evaluated using the above test methods, and the test results are shown in Table 1.

[0049] Table 1 As can be seen from Table 1, the free calcium oxide content of Examples 1-5 is all less than 0.2%, the free magnesium oxide content is all less than 1%, and the compressive strength ratio is all higher than 80%.

[0050] Compared with Examples 1-5: Comparative Examples 1 and 4 had higher contents of free calcium oxide and free magnesium oxide, and lower compressive strength; Comparative Examples 2 and 5 had similar contents of free calcium oxide and free magnesium oxide, and lower compressive strength; Comparative Examples 3 and 6 had higher contents of free calcium oxide and free magnesium oxide, and lower compressive strength; Comparative Examples 7-9 had similar contents of free calcium oxide and free magnesium oxide, and lower compressive strength.

[0051] As shown in Examples 1 and 4, without hydrothermal reaction and calcination, neither the free oxides in the steel slag can be eliminated, nor can the activity be improved. As shown in Examples 1 and 5, hydrothermal reaction alone, without calcination, can eliminate the free oxides in the steel slag, but cannot improve the activity. As shown in Examples 1 and 6, calcination alone, without hydrothermal reaction, can improve some activity, but cannot eliminate the free oxides in the steel slag. This fully demonstrates that the hydrothermal-calcination composite activation method is better than either a single hydrothermal or calcination activation method.

[0052] As shown in Example 1 and Comparative Examples 7-9, the compressive strength ratios of the mineral admixtures obtained by independently hydrothermal-calcination composite activation of iron tailings, independently hydrothermal-calcination composite activation of steel slag, and independently hydrothermal-calcination composite activation of iron tailings and steel slag followed by mixing are all lower than those obtained by Example 1, where the two are mixed first and then hydrothermal-calcination composite activation. This indicates that a synergistic effect occurs between iron tailings and steel slag during the process of mixing them first and then hydrothermal-calcination composite activation.

[0053] The test results above show that the mineral admixture prepared by the method of the present invention has a low free oxide content and a compressive strength ratio higher than 80%, indicating that the method of the present invention for preparing a highly active mineral admixture with good stability using composite activated iron tailings and steel slag can produce a highly active mineral admixture with good stability.

[0054] 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 a highly active mineral admixture with good stability from composite activated iron tailings and steel slag, characterized in that, Includes the following steps: Iron tailings, steel slag, auxiliary siliceous materials and auxiliary calcareous materials are mixed to obtain a mixture; The mixture is mixed with water and then subjected to a hydrothermal reaction to obtain the hydrothermal reaction product. The hydrothermal reaction products are calcined to obtain the highly active mineral admixture with good stability.

2. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The SiO2 content in the iron tailings is higher than 40 wt%.

3. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The CaO content in the steel slag is higher than 30 wt%.

4. The method for preparing a highly stable and active mineral admixture from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The auxiliary siliceous material includes one or more of kaolin, coal gangue, and nickel slag.

5. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The auxiliary calcium material includes one or more of slag, carbide slag, and desulfurization ash.

6. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The mass ratio of the iron tailings, steel slag, auxiliary siliceous materials, and auxiliary calcareous materials is (1~5):1:(0~0.25):(0~0.25). And / or, the mass ratio of the mixture to water is 1:(1~20).

7. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 80~200℃ for a time of 1~8h.

8. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The calcination treatment is carried out at a temperature of 400~900℃ for a time of 0.5~8h.

9. The method for preparing a highly active mineral admixture with good stability from composite activated iron tailings and steel slag as described in claim 1, characterized in that, The iron tailings, steel slag, auxiliary siliceous materials, and auxiliary calcareous materials are all ground materials, and the grinding specifically refers to grinding to a fineness of ≤1wt% on an 80μm sieve.

10. A method for preparing a highly stable and highly active mineral admixture from composite activated iron tailings and steel slag as described in any one of claims 1-9.

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