High-strength cementing material with high mining industry solid waste mixing amount and preparation method and application of high-strength cementing material

Abstract

The invention relates to the technical field of building materials, in particular to a high-strength cementing material with high mineral industry solid waste mixing amount and a preparation method and application thereof. The high-strength cementing material with high mining industry solid waste mixing amount is characterized by being prepared from the following raw materials in parts by mass: 200 to 300 parts of modified high silicon iron tailing powder, 5 to 20 parts of sulphoaluminate cement clinker, 30 to 50 parts of sintered red mud, 50 to 70 parts of desulfurized gypsum, 50 to 100 parts of steel slag, 100 to 180 parts of S95 mineral powder and 1 to 2 parts of grinding aid. According to the method, the high-silicon iron tailings and the low-melting-point molten salt are coupled and activated, the crystal structure of the iron tailings is damaged, potential activity is released, and deep utilization of the high-silicon iron tailings is achieved; and mixing the activated iron tailings with sulphoaluminate cement clinker, sintered red mud, desulfurized gypsum, a grinding aid and steel slag in proportion, grinding, and uniformly mixing with S95 mineral powder to prepare the ecological SiO2-CaO-Al2O3-Fe2O3 quaternary system cementing material. The doping amount of the high-silicon iron tailings in the cementing material exceeds 50%, and bulk consumption of the high-silicon iron tailings is achieved.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a high-strength cementitious material with high mining solid waste content, its preparation method, and its application. Background Technology

[0002] With the rapid development of my country's mining and metallurgical industries, the stockpiles of industrial solid waste such as steel tailings, red mud, and desulfurization gypsum have been increasing year by year, becoming a serious environmental and resource problem. Statistics show that my country's annual discharge of high-silicon iron tailings exceeds 500 million tons, with a cumulative stockpile reaching 600 million tons; meanwhile, the annual discharge of red mud generated by the sintering process in alumina production is approximately 100 million tons, and the annual output of desulfurization gypsum exceeds 70 million tons. If these solid wastes are stockpiled for a long period, they will not only occupy large amounts of land but also cause soil and water pollution. Therefore, how to achieve efficient resource utilization of industrial solid waste has become one of the key issues in the national "dual-carbon" strategy and the construction of green mines.

[0003] Traditional silicate cement, as the main cementing material, has high energy consumption and large carbon emissions during its production process. In order to reduce the environmental burden, the research and development of industrial solid waste-based cementing materials has become a hot topic. However, the existing technologies still have the following problems: (1) Low solid waste content. In most technologies, the solid waste content is less than 30%, which cannot achieve large-scale disposal. For example, the slag content in traditional slag powder is usually no more than 70%, while the content of steel slag powder in cementing materials is generally less than 50%. (2) Insufficient activation technology. Due to the stable crystal structure, solid wastes such as high-silicon iron tailings need to be activated by high-temperature calcination (>1000℃) or complex chemical treatment, which leads to high energy consumption and increased costs. For example, red mud from sintering requires dealkalization treatment (water washing or acid leaching), but the cost of dealkalization wastewater treatment is high. (3) Poor performance stability. Cementing materials prepared from single solid wastes have low strength and insufficient durability. For example, the 28-day compressive strength of pure iron tailings cementing materials is only 10-15 MPa, which is far lower than the 40-50 MPa of ordinary cement.

[0004] Therefore, there is a need to provide a high-strength cementitious material with a high content of mining solid waste. Summary of the Invention

[0005] In view of this, the present invention provides a high-strength cementitious material with high mining solid waste content, its preparation method, and its application. This invention utilizes multi-source solid waste co-utilization technology and low-temperature molten salt activation technology to prepare a low-cost solid waste-based cementitious material with an iron tailings content exceeding 50%, further replacing cement-based filling materials prepared using traditional methods. This avoids the environmental problems caused by cement production and improves the utilization rate and added value of iron tailings. Furthermore, the slump and compressive strength of the filling material prepared using this cementitious material meet the requirements of GB / T 39489-2020.

[0006] To achieve the above objectives, this application provides the following technical solution: A high-strength cementitious material with high mineral solid waste content comprises the following raw materials by mass: 200-300 parts of modified high-silicon iron tailings powder, 5-20 parts of sulfoaluminate cement clinker, 30-50 parts of sintered red mud, 50-70 parts of desulfurized gypsum, 50-100 parts of steel slag, 100-180 parts of S95 mineral powder, and 1-2 parts of grinding aid.

[0007] Modified high-silicon iron tailings powder releases active SiO2 and Ca. 2+ CSH gel is generated.

[0008] Anhydrous calcium sulfoaluminate in sulfoaluminate cement clinker reacts with water to form ettringite (AFt) and alumina gel (AH3).

[0009] Desulfurized gypsum provides SO4 2- This inhibits the conversion of AFt to monosulfide-type hydrated calcium sulfoaluminate (AFm) and maintains the stability of AFt.

[0010] Free CaO in steel slag powder hydrates to form Ca(OH)2, which acts as an alkaline activator to activate the pozzolanic activity of modified high-silicon iron tailings powder and S95 ore powder.

[0011] The active SiO2 and Al2O3 in S95 mineral powder react in an alkaline environment to generate CSH and CAH gels, which fill the pores and increase the density.

[0012] Modified high-silicon iron tailings powder mainly provides active silicon, sulfoaluminate cement provides highly active aluminum, and desulfurized gypsum provides SO4. 2- The active components in the sintering red mud ensure an alkaline environment, while the steel slag ensures the Ca content in the system. 2+ The concentration and synergistic effect of various solid wastes generate a large amount of ettringite and CSH gel, improving the compressive strength of cementitious materials. S95 slag powder contains a large amount of glass, which can be used for secondary cementing to ensure continuous strength growth.

[0013] SiO2 + Ca(OH)2 + H2O → CSH Al₂O₃ + Ca(OH)₂ + H₂O → CAH Preferably, the modified high-silicon iron tailings powder contains ≥40% SiO2, 15-25% potassium feldspar, 10-20% sodium feldspar, and 5-10% biotite; the sulfoaluminate cement clinker has an alkalinity coefficient of 0.9-1; the sintered red mud contains 8-15% Al2O3 and 4-6% Na2O; the desulfurized gypsum is anhydrous desulfurized gypsum with a content ≥90%; the steel slag contains <0.5% total free CaO and free MgO, and an activity index of 80-85% after 28 days; and the S95 ore powder has a specific surface area of ​​400-450 m². 2 / kg, and the activity index after 28 days is 95-105%.

[0014] Preferably, the grinding aid is composed of sodium hexametaphosphate, methylcellulose, and diethylisopropanolamine in a mass ratio of 1:0.2-0.5:0.1-0.3. The grinding aid can improve powder flowability, reduce particle agglomeration, increase specific surface area, accelerate hydration reaction, and simultaneously inhibit excessive growth of AFt, preventing loose structure and promoting CSH gel densification.

[0015] More preferably, the modified high-silicon iron tailings powder is prepared by the following method: iron tailings with a mass ratio of 1:0.1 to 0.3 are mixed with low-melting-point molten salt and placed in a closed reaction vessel, heated to 250 to 350°C, kept at the temperature in an inert atmosphere N2 for 1 to 2 hours, and then naturally cooled to obtain modified high-silicon iron tailings powder.

[0016] Low-melting-point molten salts transform into liquid phases at high temperatures, permeating and disrupting the tailings lattice, increasing the specific surface area, and releasing the encapsulated SiO2-Al2O3 active sites, thus releasing NO3 from the molten salt. - It reacts with Fe2O3 and SiO2 in the tailings to generate soluble aluminoferrites (such as NaFeSiO4), which enhances the activity of pozzolanic ash. Compared with traditional high-temperature calcination (>800℃), energy consumption is reduced by 40%, and the deactivation of active components by sintering is avoided.

[0017] More preferably, the low-melting-point molten salt is a ternary salt of LiNO3-NaNO3-KNO3, and the mass ratio of LiNO3, NaNO3 and KNO3 in the ternary salt of LiNO3-NaNO3-KNO3 is 1:1 to 3:1 to 3.

[0018] A method for preparing a high-strength cementitious material with high mineral solid waste content includes the following steps: S1. Iron tailings are coupled with low-melting-point molten salt for thermal activation to obtain modified high-silicon iron tailings powder. S2. Modified high-silicon iron tailings powder, sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag are mixed and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total grinding aid volume. The grinding process continues until the specific surface area of ​​the mixed grinding media reaches 350–450 m². 2 / kg; S3. Mix the grinding material in S2 with the mineral powder in S95 evenly to obtain the cementitious material.

[0019] A filling material comprising the above-mentioned cementitious material, unactivated iron tailings, water and additives, wherein the mass ratio of the cementitious material, unactivated iron tailings, water and additives is 1:6 to 10:3 to 11:0.01 to 0.3.

[0020] Preferably, the admixture consists of a water-reducing agent and an air-entraining agent in a mass ratio of 1-2:0.1-0.3.

[0021] More preferably, the water-reducing agent is at least one selected from polycarboxylate high-performance water-reducing agent, calcium lignosulfonate, and melamine-based water-reducing agent. The water-reducing agent can reduce the surface tension of the filling material, increase the surface water film thickness, and ensure the performance of the filling material. Polycarboxylate high-performance water-reducing agent is preferred.

[0022] More preferably, the air-entraining agent is at least one of fatty alcohol polyoxyethylene ether, sodium dodecyl sulfonate, and triterpenoid saponins.

[0023] Beneficial effects: (1) This invention couples high-silicon iron tailings with low-melting-point molten salt for low-temperature thermal activation, thereby destroying the crystal structure of the iron tailings and releasing their potential activity. This allows the tailings to exceed the technical bottleneck of 50% content, achieving deep utilization of high-silicon iron tailings. The activated iron tailings are further mixed with sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, grinding aid, and steel slag in a certain mass ratio and ground to a certain specific surface area. Then, it is uniformly mixed with S95 mineral powder to prepare an ecological SiO2-CaO-Al2O3-Fe2O3 quaternary cementitious material. The high-silicon iron tailings content in this cementitious material exceeds 50%, realizing the large-scale consumption of high-silicon iron tailings.

[0024] (2) This invention significantly improves the early and late strength of cementitious materials by utilizing the early strength effect of sulfoaluminate cement clinker and the alkali activation effect of sintered red mud, and establishes a multi-source solid waste synergistic system. By adopting a single-stage vertical mill grinding process, the specific surface area of ​​the ecological cementitious materials is controlled at 400-500 m² / kg, which ensures both activity and reduces energy consumption, saving more than 30% energy compared to the traditional two-stage grinding process.

[0025] (3) This invention prepares a filling slurry by mixing ecological cementitious material with unactivated iron tailings and water. The filling slurry can be applied to projects such as filling goaf or backfilling trenches. The ecological cementitious material prepared by this invention undergoes low-temperature thermal activation and one-time grinding. The process is simple, the production energy consumption is low, the iron tailings content in the raw materials is high, the prepared filling material has good workability and low cost, and has good economic and ecological benefits. Detailed Implementation

[0026] The present application will now be described in detail with reference to embodiments. The various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will understand that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0027] A high-strength cementitious material with high mineral solid waste content, comprising the following raw materials by mass parts: 200-300 parts of modified high-silicon iron tailings powder, 5-20 parts of sulfoaluminate cement clinker, 30-50 parts of sintered red mud, 50-70 parts of desulfurized gypsum, 50-100 parts of steel slag, 100-180 parts of S95 mineral powder, and 1-2 parts of grinding aid. Among them, the modified high-silicon iron tailings powder contains ≥40% SiO2, 15-25% potassium feldspar, 10-20% sodium feldspar, and 5-10% biotite; The basicity coefficient of sulfoaluminate cement clinker is 0.9–1; In sintered red mud, Al2O3 accounts for 8-15% and Na2O accounts for 4-6%; The desulfurized gypsum is anhydrous desulfurized gypsum with a content of ≥90%; The total content of free CaO and free MgO in steel slag is <0.5%, and the activity index after 28 days is 80-85%. The specific surface area of ​​S95 mineral powder is 400-450 m². 2 / kg, and the activity index after 28 days was 95-105%; The grinding aid is composed of sodium hexametaphosphate, methylcellulose, and diethylisoisopropanolamine in a mass ratio of 1:0.2-0.5:0.1-0.3.

[0028] A method for preparing a high-strength cementitious material with high mineral solid waste content includes the following steps: S1. Iron tailings with a mass ratio of 1:0.1 to 0.3 are mixed with low-melting-point molten salt and placed in a closed reactor. The temperature is raised to 250 to 350°C and kept at this temperature in an inert atmosphere of N2 for 1 to 2 hours. After natural cooling, modified high-silicon iron tailings powder is obtained. The low-melting-point molten salt is a ternary salt of LiNO3-NaNO3-KNO3, and the mass ratio of LiNO3, NaNO3 and KNO3 in the LiNO3-NaNO3-KNO3 ternary salt is 1:1 to 3:1 to 3. S2. Modified high-silicon iron tailings powder, sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag are mixed and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total grinding aid volume. The grinding process continues until the specific surface area of ​​the mixed grinding media reaches 350–450 m². 2 / kg; S3. Mix the grinding material in S2 with the mineral powder in S95 evenly to obtain the cementitious material.

[0029] A filling material includes the aforementioned cementitious material, unactivated iron tailings, water, and additives. The mass ratio of the cementitious material, unactivated iron tailings, water, and additives is 1:6–10:3–11:0.01–0.3. The additives consist of a water-reducing agent and an air-entraining agent in a mass ratio of 1–2:0.1–0.3. The water-reducing agent is at least one of polycarboxylate superplasticizer, calcium lignosulfonate, and melamine-based water-reducing agent. The air-entraining agent is at least one of fatty alcohol polyoxyethylene ether, sodium dodecyl sulfonate, and triterpenoid saponins.

[0030] The iron tailings used in this invention were selected from Zhangzhuang Iron Mine, and the water-reducing agent and air-entraining agent were purchased from Shandong Huadi Construction Technology Co., Ltd.

[0031] Example 1 A high-strength cementitious material with high mineral solid waste content, the composition of which is shown in Table 1, and the specific preparation steps of which are as follows: S1. Iron tailings with a mass ratio of 1:0.1 are mixed with low-melting-point molten salt. The mixture is placed in a sealed reactor, heated to 280±10℃, and kept at this temperature in an inert atmosphere of N2 for 1 hour. After natural cooling, modified high-silicon iron tailings powder is obtained. The low-melting-point molten salt is a ternary salt of LiNO3-NaNO3-KNO3, and the mass ratio of LiNO3, NaNO3 and KNO3 in the LiNO3-NaNO3-KNO3 ternary salt is 1:1.5:1.5. S2. The modified high-silicon iron tailings powder obtained in S1 is mixed with sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag, and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total mass of the grinding aid. Grinding continues until the specific surface area of ​​the mixed powder is 350–450 m².2 / kg; S3. Mix the grinding material in S2 with the mineral powder in S95 evenly to obtain a cementitious material.

[0032] Example 2 A high-strength cementitious material with high mineral solid waste content, the composition of which is shown in Table 1, and the specific preparation steps of the cementitious material are as follows: S1. Iron tailings with a mass ratio of 1:0.2 are mixed with low-melting-point molten salt. The mixture is placed in a sealed reactor, heated to 300±10℃, and kept at this temperature in an inert atmosphere of N2 for 1.5h. After natural cooling, modified high-silicon iron tailings powder is obtained. The composition of the low-melting-point molten salt is the same as that in Example 1. S2. The obtained modified high-silicon iron tailings powder is mixed with sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag, and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total amount of grinding aid. The grinding process continues until the specific surface area of ​​the mixed powder is 350–450 m². 2 / kg; S3. Mix the grinding material and S95 mineral powder evenly to obtain a cementitious material.

[0033] Example 3 A high-strength cementitious material with high mineral solid waste content, the composition of which is shown in Table 1, and the specific preparation steps of the cementitious material are as follows: S1. Iron tailings with a mass ratio of 1:0.3 were mixed with low-melting-point molten salt. The mixture was placed in a closed reactor and heated to 350±10℃. It was kept at this temperature in an inert atmosphere of N2 for 2 hours and then naturally cooled to obtain modified high-silicon iron tailings powder. The composition of the low-melting-point molten salt was the same as that in Example 1. S2. The obtained modified high-silicon iron tailings powder is mixed with sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag, and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total amount of grinding aid. The grinding process continues until the specific surface area of ​​the mixed powder is 350–450 m². 2 / kg; S3. Mix the grinding material and S95 mineral powder evenly to obtain a cementitious material.

[0034] Comparative Example 1 A cementitious material is prepared in the same way as in Example 1, except that the composition is different. The cementitious material in this comparative example uses unmodified high-silicon iron tailings powder (excluding step S1 in Example 1, while steps S2 / S3 are the same as in Example 1). The specific composition is shown in Table 1.

[0035] Comparative Example 2 A cementitious material is prepared in the same way as in Example 1, except that the composition is different. No grinding aid is used in this comparative example. The specific composition is shown in Table 1.

[0036] Table 1. Specific components of the cementitious materials in Examples 1-3 and Comparative Examples 1-2. Examples 4-6 Examples 4-6 of this invention provide a filling material, the composition of which is shown in Table 2, and the cementing materials used correspond to the cementing materials prepared in Examples 1-3, respectively. The specific preparation steps are as follows: S1. Accurately weigh the mass (in grams) of cementitious materials, unactivated iron tailings, additives and water, as shown in Table 1. S2. Mix the weighed cementitious materials and additives evenly, pour them into a standard mortar mixer, add the weighed water and unactivated iron tailings, and stir at 140 r / min for 300 s to obtain the filling material.

[0037] Comparative Examples 3-4 Comparative Examples 3-4 of the present invention provide a filling material, the composition of which is shown in Table 2, and the gelling material used corresponds to the gelling material prepared in Comparative Examples 1-2 respectively. The specific preparation steps are the same as those in Examples 4-6.

[0038] Comparative Example 5 Comparative Example 1 of the present invention provides a filling material, wherein the composition of the filling material is shown in Table 2. Compared with Example 4, Comparative Example 1 uses P·O42.5 silicate cement instead of the cementitious material in Comparative Example 4; the specific preparation steps of the filling material are the same as those of the filling material in Example 4.

[0039] Table 2 shows the specific components of the filling materials in Examples 4-6 and Comparative Examples 3-5. Test Example The properties of the filling materials obtained in Examples 4-6 and Comparative Examples 3-5 were tested according to the following steps: (1) Measure the slump of the filling material using a filling material flow cone funnel; (2) The well-stirred filling material was put into a standard mold (70.7mm*70.7mm*70.7mm) evenly coated with butter. After vibrating and smoothing, the mold was removed after being placed in a standard curing box for 24 hours. The cured flat plate was placed in a standard constant temperature curing box (temperature set at 20±1℃, humidity 95%RH) and the compressive strength was tested at 3d, 7d and 28d respectively. The specific results are shown in Table 3.

[0040] Table 3. Performance test results of the filling materials obtained in Examples 4-6 and Comparative Examples 3-5. The test results in Table 3 show that the slump and compressive strength at various ages of the filling materials prepared in Examples 4-6 of this invention are superior to those in Comparative Examples 3-5. This indicates that the filling materials prepared using high-strength cementitious materials with high mining solid waste content have better workability and mechanical properties. Comparative Example 3 did not undergo tailings modification treatment, and Comparative Example 4 did not add grinding aids; the prepared cementitious materials had lower strength, and the early strength of the filling materials did not meet the standard requirements. A comparison between Example 4 and Comparative Example 5 reveals that the high-strength cementitious materials with high mining solid waste content have better mechanical properties than P·O42.5 silicate cement. In summary, the high-strength cementitious materials with high mining solid waste content prepared by this invention exhibit excellent workability and mechanical properties.

[0041] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-strength cementitious material with high mineral solid waste content, characterized in that, By weight, it includes the following raw materials: 200-300 parts of modified high-silicon iron tailings powder, 5-20 parts of sulfoaluminate cement clinker, 30-50 parts of sintered red mud, 50-70 parts of desulfurized gypsum, 50-100 parts of steel slag, 100-180 parts of S95 mineral powder, and 1-2 parts of grinding aid.

2. The high-strength cementitious material with high mining solid waste content according to claim 1, characterized in that, The modified high-silicon iron tailings powder contains ≥40% SiO2, 15-25% potassium feldspar, 10-20% sodium feldspar, and 5-10% biotite; the sulfoaluminate cement clinker has an alkalinity coefficient of 0.9-1; the sintered red mud contains 8-15% Al2O3 and 4-6% Na2O; the desulfurized gypsum is anhydrous desulfurized gypsum with a content ≥90%; the steel slag contains <0.5% total free CaO and free MgO, and has an activity index of 80-85% after 28 days; the S95 ore powder has a specific surface area of ​​400-450 m². 2 / kg, and the activity index after 28 days is 95-105%.

3. The high-strength cementitious material with high mining solid waste content according to claim 1, characterized in that, The grinding aid is composed of sodium hexametaphosphate, methylcellulose, and diethylisoisopropanolamine in a mass ratio of 1:0.2-0.5:0.1-0.

3.

4. The high-strength cementitious material with high mining solid waste content according to claim 1 or 2, characterized in that, The modified high-silicon iron tailings powder is prepared by the following method: iron tailings with a mass ratio of 1:0.1 to 0.3 are mixed with low-melting-point molten salt and placed in a closed reaction vessel. The temperature is raised to 250 to 350°C and kept at the temperature in an inert atmosphere of N2 for 1 to 2 hours. After natural cooling, the modified high-silicon iron tailings powder is obtained.

5. The high-strength cementitious material with high mining solid waste content according to claim 4, characterized in that, The low-melting-point molten salt is a ternary salt of LiNO3-NaNO3-KNO3, and the mass ratio of LiNO3, NaNO3 and KNO3 in the ternary salt is 1:1 to 3:1 to 3.

6. A method for preparing a high-strength cementitious material with high mining solid waste content as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Iron tailings are coupled with low-melting-point molten salt for thermal activation to obtain modified high-silicon iron tailings powder. S2. Modified high-silicon iron tailings powder, sulfoaluminate cement clinker, sintered red mud, desulfurized gypsum, and steel slag are mixed and then ground in a single-stage vertical mill. Grinding aid is sprayed every 5 minutes during the grinding process, for a total of three sprays. Each spray is 1 / 3 of the total grinding aid volume. The grinding process continues until the specific surface area of ​​the mixed grinding media reaches 350–450 m². 2 / kg; S3. Mix the grinding material in S2 with the mineral powder in S95 evenly to obtain the cementitious material.

7. A filling material, characterized in that, The mixture comprises the cementitious material as described in any one of claims 1 to 5, unactivated iron tailings, water, and additives, wherein the mass ratio of the cementitious material, unactivated iron tailings, water, and additives is 1:6 to 10:3 to 11:0.01 to 0.

3.

8. The filling material according to claim 7, characterized in that, The admixture consists of a water-reducing agent and an air-entraining agent in a mass ratio of 1-2:0.1-0.

3.

9. The filling material according to claim 8, characterized in that, The water-reducing agent is at least one of polycarboxylate high-performance water-reducing agent, calcium lignosulfonate, and melamine-based water-reducing agent.

10. The filling material according to claim 8 or 9, characterized in that, The air-entraining agent is at least one of fatty alcohol polyoxyethylene ether, sodium dodecyl sulfonate, and triterpenoid saponins.

Images