Low hydration heat high-iron tailing micro-powder concrete and preparation method thereof

Abstract

The application discloses a kind of low hydration heat large amount of iron tailings micro powder concrete and preparation method thereof, the concrete includes the components as follows by weight fraction: iron tailings micro powder 144~192 parts, Portland cement: 180~240 parts, slag powder 36~48 parts, sand 794~914 parts, stone 913~932 parts, water 154~173 parts, additive 8.6~11.5 parts.The application is preprocessed to iron tailings micro powder by physical-chemical composite activation technology to replace traditional fly ash, which can effectively reduce the particle size of iron tailings micro powder, enhance the activity of iron tailings micro powder, improve the density and rheological properties of concrete;By large amount of iron tailings micro powder application, the hydration kinetics of cementitious material system can be significantly improved, the hydration heat can be reduced, and the generation of concrete temperature difference crack can be reduced;It can also promote resource recycling, not only solve the problem of industrial waste iron tailings, effectively reduce the environmental burden, but also contribute to improving the environment and saving resources;At the same time, it also effectively reduces the comprehensive cost of concrete, realizes cost reduction and efficiency improvement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to a low-hydraulic-heat large-mixing-amount iron tailing micro-powder concrete and a preparation method thereof. BACKGROUND

[0002] Iron tailings refer to solid waste remaining after a series of beneficiation processes such as crushing, grinding, magnetic separation and flotation in the process of iron ore beneficiation. Large amounts of iron tailings not only occupy and pollute land resources, but also pose a certain safety hazard.

[0003] At present, the application research of iron tailings in the field of building materials mainly focuses on iron tailings re-election, mine filling and ecological restoration, and relatively less research is conducted on iron tailing powder as an admixture. Traditional mineral admixtures are often used in concrete. On the other hand, concrete with high cement content has a large amount of hydration heat during preparation and service, which produces temperature stress and causes temperature cracks.

[0004] After searching, the Chinese patent application file with the publication number CN107344832A discloses a concrete based on slag-limestone powder auxiliary cementitious material, wherein the water-binder ratio of the concrete is between 0.37 and 0.51, and the weight percentage of the components of the concrete is as follows: cementitious material 14% to 20%, sand 27% to 33%, stone 44% to 46%, water 7.1% to 7.4%, and the weight percentage of the additive in the cementitious material is 1.5%; the cementitious material is mixed by slag, limestone powder and Portland cement, and the weight percentage is as follows: ordinary Portland cement 50%, slag 30%, and limestone powder 20%, the specific surface area of the limestone powder is 350 m 2 / kg, 450 m 2 / kg or 650 m 2 / kg.” Although the concrete in the application uses iron tailings to reduce the production cost of composite cement and concrete, the limestone powder is used as an auxiliary cementitious material, which causes the following two problems: on the one hand, the quality of limestone powder is unstable, and the mud content is large, which can absorb a large amount of free water, resulting in rapid loss of concrete slump; on the other hand, the addition of limestone powder has potential carbon-sulfur-silicate-sulfate corrosion, which is not conducive to the durability of concrete. In summary, the application has certain limitations.

[0005] Therefore, it is urgent to design a low-hydraulic-heat large-mixing-amount iron tailing micro-powder concrete and a preparation method thereof, which can maximize the reduction of cement content and seek a low-hydraulic-heat admixture that can replace traditional mineral admixtures to achieve temperature control and crack prevention. SUMMARY

[0006] To address the problems existing in the prior art, the present invention aims to provide a low-heat-of-hydration, high-volume iron tailings powder concrete and its preparation method. This method utilizes a large amount of byproducts generated during the iron tailings production process that are difficult to dispose of, while reducing the heat of hydration of the concrete to achieve temperature control and crack prevention. Furthermore, by treating the iron tailings powder with physical-chemical composite modification technology, the performance of the concrete is optimized, reducing the risk of temperature stress and crack formation, while also lowering the overall cost of the concrete and promoting resource recycling.

[0007] To achieve the above and other related objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete, comprising the following steps:

[0009] S1. Preparation of iron tailings powder:

[0010] Iron tailings were treated using a physical-chemical composite modification technique, firstly by ball milling to obtain a specific surface area ≥150 m². 2 / kg of iron tailings powder is then ball-milled a second time with the addition of grinding aids and silane coupling agents to obtain a fineness of ≤3% residue on a 45μm square-hole sieve and a specific surface area ≥500m². 2 / kg of iron tailings powder;

[0011] S2. Concrete preparation:

[0012] Weigh out the cementitious materials, sand, stone, water, and admixtures according to the mass fractions, and mix them evenly to obtain a concrete mixture; the cementitious materials include cement, slag powder, and the iron tailings powder obtained in step S1;

[0013] S3, Concrete Forming:

[0014] The concrete mixture obtained in step S2 is placed into a concrete adiabatic temperature rise test container, and temperature change data is collected in real time using computer control; at the same time, it is placed into a compressive strength test mold, and after 1 day, it is demolded and placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of more than 95% for curing until the corresponding age is reached.

[0015] As a preferred technical solution, in step S1, the grinding aid includes any one or two of triethanolamine, stearic acid, and sodium hexametaphosphate.

[0016] Furthermore, step S1 includes the following specific steps:

[0017] S1-1. Perform a single ball milling on the iron tailings to obtain a specific surface area ≥150m². 2 / kg iron tailings powder:

[0018] The crushed iron tailings were first ball-milled using a ball mill with steel balls as the grinding media, at a ball-to-material ratio of 2:1, to obtain a specific surface area ≥150m². 2 / kg iron tailings powder;

[0019] S1-2. Add grinding aid powder and perform secondary ball milling on the iron tailings powder, and add silane coupling agent to modify the iron tailings powder to obtain a specific surface area ≥500m². 2 / kg of iron tailings powder:

[0020] The iron tailings powder obtained in step S1-1 was subjected to a second ball milling using steel balls as the grinding media, with a ball-to-material ratio of 3:1 to 10:1. Grinding aids were added at 0.1% to 0.15% of the iron tailings powder mass; simultaneously, silane coupling agents at 1% to 3% of the iron tailings powder mass were added. During the second ball milling process, the iron tailings powder was modified to obtain a specific surface area ≥ 500 m². 2 / kg of iron tailings powder.

[0021] As a preferred technical solution, in the cementitious material of step S2, the proportion of iron tailings powder is 40%, the proportion of cement is 50%, and the proportion of slag powder is 10%.

[0022] As a preferred technical solution, the low-hydration-heat, high-volume iron tailings micro-powder concrete comprises the following components by weight: 144-192 parts iron tailings micro-powder, 180-240 parts silicate cement, 36-48 parts slag powder, 794-914 parts sand, 913-932 parts stone, 154-173 parts water, and 8.6-11.5 parts admixture.

[0023] Furthermore, the slag powder is S95 ore powder with a specific surface area of ​​443 m². 2 / kg, flowability ratio 98%, 28-day activity index 101%.

[0024] Furthermore, the cement is 42.5 ordinary Portland cement, with a 3-day heat of hydration of 226 J / g, a standard consistency water requirement of 26.8%, and a specific surface area of ​​410 m². 2 / kg.

[0025] Furthermore, the sand is calcareous manufactured sand with a fineness modulus of 2.7, an MB value of 0.75 g / kg, and a stone powder content of 2.6%; the stone is 5 mm to 20 mm continuously graded crushed stone with a mud powder content of 0.4% and a porosity of 40%.

[0026] Furthermore, the admixture is a retarded polycarboxylate superplasticizer with a water reduction rate of 30% and an initial setting time difference of +130 min.

[0027] In a second aspect, the present invention provides a low-heat-of-hydration, high-volume iron tailings micro-powder concrete, wherein the low-heat-of-hydration, high-volume iron tailings micro-powder concrete is prepared by the preparation method according to any one of claims 1-9.

[0028] As described above, the present invention has the following beneficial effects:

[0029] (1) The present invention provides a low-heat-of-hydration, high-volume iron tailings micro-powder concrete and its preparation method. In the preparation of iron tailings micro-powder, a physical-chemical composite activation technology is adopted. Through mechanical grinding, the particle size of iron tailings micro-powder can be effectively reduced, making the particle size distribution of iron tailings micro-powder more reasonable and filling the pores of the slurry more tightly, thereby improving the density of concrete. At the same time, by adding a silane coupling agent in the secondary ball mill, the active groups in the silane coupling agent react chemically with the hydroxyl groups on the surface of iron tailings micro-powder, improving the dispersibility and compatibility of iron tailings micro-powder in different matrix materials, thereby optimizing the rheological properties of cement slurry and reducing the bleeding and segregation of concrete.

[0030] (2) The present invention provides a low-heat-of-hydration, high-dosage iron tailings micro-powder concrete and its preparation method. The high-dosage iron tailings micro-powder is used as a substitute material to replace traditional fly ash, which can significantly and effectively improve the hydration kinetics of the cementitious material system. In addition, it can effectively reduce the hydration rate of concrete in the early stage, thereby reducing the excessive heat generated by the hydration reaction and effectively controlling the total heat released by hydration. Furthermore, it can greatly alleviate the risk of cracking caused by uneven temperature stress inside the concrete, thereby significantly reducing the cracking problem of concrete in practical applications and improving the overall durability and safety of concrete structures.

[0031] (3) The present invention provides a low-heat-of-hydration, high-volume iron tailings powder concrete and its preparation method, which uses iron tailings powder. Since iron tailings powder is an industrial waste, its acquisition cost is relatively low. It is pretreated by physical-chemical synergistic modification technology, and modified by secondary mechanical grinding and silane coupling agent, so that iron tailings powder can be efficiently and in high volume to replace some of the more expensive traditional raw materials. This not only solves the problem of iron tailings waste disposal, effectively reduces the environmental burden, and promotes the recycling of resources, but also contributes to improving the environment and saving resources. At the same time, due to the large-volume application of iron tailings powder, the overall cost of concrete is effectively reduced, achieving cost reduction and efficiency improvement. Attached Figure Description

[0032] Figure 1 These are the hydration heat measurement results of the cementitious materials at 3 days in Examples 1-3 of this invention. Detailed Implementation

[0033] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0034] In the description of this invention, it should be noted that, unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in this specification are all common raw materials on the market and technical methods well known to those skilled in the art.

[0035] Example 1

[0036] This embodiment provides a low-heat-of-hydration, high-volume iron tailings micro-powder concrete and its preparation method. The low-heat-of-hydration, high-volume iron tailings micro-powder concrete is composed of the following raw material components by weight: 144 parts iron tailings micro-powder, 180 parts ordinary Portland cement, 36 parts slag powder, 914 parts sand, 913 parts stone, 173 parts water, and 8.6 parts admixtures. Wherein:

[0037] The slag powder is S95 ore powder with a specific surface area of ​​443 m². 2 / kg, fluidity ratio 98%, 28-day activity index 101%; by using slag powder and iron tailings micro powder in combination, the particle size distribution can be further optimized, and the active ingredients can be mutually supplemented, thereby improving the workability and mechanical properties of concrete. At the same time, the synergistic effect of the two makes the internal structure of concrete more compact, reducing heat accumulation caused by the presence of pores, improving the thermal conductivity of concrete, and allowing heat to be more easily conducted away through a well-filled concrete structure, reducing the maximum internal temperature of concrete and reducing the risk of temperature stress and temperature cracking.

[0038] The cement is 42.5 ordinary Portland cement, with a 3-day heat of hydration of 226 J / g, a standard consistency water requirement of 26.8%, and a specific surface area of ​​410 m². 2 / kg; In this embodiment, by using cement with relatively low tricalcium silicate and tricalcium aluminate content, the hydration process generates lower heat of hydration, slower heat release during hydration, and lower peak temperature, thereby effectively controlling the temperature rise rate and maximum temperature of the concrete; In addition, by using cement with higher fineness, it helps to improve the early strength of the concrete, enabling the concrete to reach sufficient strength in a shorter time to withstand the loads during construction.

[0039] The sand is calcareous manufactured sand with a fineness modulus of 2.7, an MB value of 0.75 g / kg, and a stone powder content of 2.6%. The use of calcareous manufactured sand not only ensures the strength and durability of the concrete, but also, due to its calcareous properties, complements the combined use of slag powder and iron tailings powder, further enhancing the concrete's freeze-thaw resistance. Simultaneously, during concrete preparation, the calcareous manufactured sand can bond well with the cement paste, forming a more uniform and stable interface transition zone, thereby improving the overall performance of the concrete. Furthermore, the use of calcareous manufactured sand also helps reduce concrete shrinkage and cracking, improving its crack resistance.

[0040] The stone is a continuously graded crushed stone ranging from 5mm to 20mm, with a mud powder content of 0.4% and a porosity of 40%. By using crushed stone, a good skeletal structure is ensured in the concrete, which is beneficial to improving the compressive strength and stability of the concrete. At the same time, the lower mud powder content and porosity help to reduce the water consumption of the concrete mix, thereby reducing the water-cement ratio of the concrete and further improving the durability and impermeability of the concrete. In addition, in this embodiment, by precisely controlling the particle size distribution and quality of the crushed stone, the overall performance of the concrete is significantly improved.

[0041] The admixture is a retarded polycarboxylate superplasticizer with a water reduction rate of 30% and an initial setting time difference of +130 min. By using a retarded polycarboxylate superplasticizer, the fluidity and strength of concrete can be improved, cement usage can be reduced, slump loss can be reduced, durability can be improved, compatibility with different cements and admixtures can be enhanced, and costs and environmental impact can be reduced. At the same time, it also has a high water reduction rate and a significant retarding effect, thereby optimizing the workability and long-term performance of concrete.

[0042] The preparation method includes the following steps:

[0043] S1. Preparation of iron tailings powder:

[0044] By employing grinding aids and physical-chemical composite modification techniques to treat iron tailings, the surface and structural properties of the iron tailings are deeply optimized, resulting in a fineness of ≤3% residue on a 45μm square-hole sieve and a specific surface area ≥500m². 2 / kg and other technical indicators meet the requirements for iron tailings powder.

[0045] The technical specifications refer to the group standard T / CECS10103-2020 "Lead-Zinc and Iron Tailings Micropowder for Cement and Concrete" issued by the China Association for Engineering Construction Standardization. The technical requirements for iron tailings micropowder used in concrete are specified in Table 1.

[0046] Table 1 Technical Requirements for Iron Tailings Powder Used in Concrete

[0047]

[0048] The final iron tailings powder contains 10%–15% Fe2O3, 50%–70% SiO2, and 1%–2% SO3; the methylene blue value of the iron tailings powder is 0.80 g / kg, and the water requirement ratio is 98%–100%.

[0049] S1-1. The crushed iron tailings were first ball-milled using a ball mill with steel balls as the grinding media, with a ball-to-material ratio of 2:1, resulting in a specific surface area of ​​160 m². 2 / kg iron tailings powder.

[0050] S1-2. The iron tailings powder obtained in step S1-1 is subjected to a second grinding process using a ball mill with a ball-to-powder ratio of 4:1 at a rotation speed of 240 r·min⁻¹. During the ball milling process, 0.1% (by weight of the iron tailings powder) of triethanolamine is added as a grinding aid; simultaneously, 1% (by weight of the iron tailings powder) of silane coupling agent is added to modify the iron tailings powder during the second grinding process, resulting in a specific surface area of ​​560 m². 2 / kg of iron tailings powder.

[0051] In this embodiment, steel balls are used as grinding media in both ball milling processes. The high density and hardness of the steel balls can effectively apply impact and grinding force to the ore. Through two steel ball grinding processes, iron tailings can be effectively ground into micro powder. Specifically, the powder material obtained after the first ball milling process of the iron tailings as raw material—iron tailings powder—has a relatively wide range of fineness. The micro powder material obtained after the second ball milling process and modification technology—iron tailings micro powder—can usually reach the micron level in fineness. Furthermore, steel balls, as the most common grinding media, are easier to obtain and use, reducing the complexity of the preparation operation.

[0052] The iron tailings powder used in this application has more active sites on its surface after ball milling. When modified with a silane coupling agent, the silane coupling agent can more effectively bind to the active sites on the surface of the iron tailings powder. The active groups of the silane coupling agent will more easily react chemically with the hydroxyl groups on the surface of the iron tailings powder to form chemical bonds. This composite modification method allows the iron tailings powder to fully exert the synergistic effect of physical and chemical modification, comprehensively improving the performance of the iron tailings powder. At the same time, it can play a role in dispersing heat in concrete, effectively reducing the heat of hydration of concrete.

[0053] S2. Concrete preparation:

[0054] Weigh out the cementitious material, sand, stone, water, and water-reducing agent according to the specified mass ratios, pour them into a concrete mixer, and mix them evenly to obtain a concrete mixture. The cementitious material is a mixture of cement, slag powder, and iron tailings powder. Specifically, the proportion of iron tailings powder is 40%, the proportion of cement is 50%, and the proportion of slag powder is 10%.

[0055] In this embodiment, all the above-mentioned raw materials are directly fed into the mixer for mixing using the "one-time feeding method" after weighing.

[0056] S3, Concrete Forming:

[0057] The concrete mixture was placed in a concrete adiabatic temperature rise test container, and temperature change data was collected in real time using computer control. At the same time, it was placed in a compressive strength test mold, and after 1 day, it was demolded and placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of more than 95% for curing until it reached the age of 28 days and 60 days, respectively.

[0058] In building engineering design and construction specifications, 28-day strength is the basic standard for concrete strength acceptance, and it is generally stipulated that 28-day compressive strength is used as the basis for evaluating concrete strength grade. In this implementation, in addition to using 28 days, a 60-day age period was also adopted, with the following considerations: After adding a large amount of mineral admixtures (i.e., iron tailings powder and mineral powder used in this application), secondary hydration reactions will occur in the concrete. This process may last for a long time, resulting in a relatively slow development of concrete strength. Therefore, at 60 days, these secondary hydration reactions contribute more significantly to the concrete strength, enabling further improvement in concrete strength and better reflecting the long-term performance of concrete. In summary, when studying the performance of new concrete materials or concrete with different mix proportions, setting 28 days and 60 days allows for a more comprehensive comparison of concrete performance changes; the 28-day age period can reflect the early performance differences of concrete, while the 60-day age period helps to observe the later strength development trend of concrete and evaluate the applicability of new materials.

[0059] Example 2

[0060] This embodiment provides a low-heat-of-hydration, high-volume iron tailings micro-powder concrete and its preparation method. The low-heat-of-hydration, high-volume iron tailings micro-powder concrete is made from the following raw material components by weight: 144 parts iron tailings micro-powder, 180 parts ordinary silicate cement, 36 parts slag powder, 914 parts manufactured sand, 913 parts stone, 173 parts water, and 8.6 parts admixture, the same as in Embodiment 1.

[0061] The preparation method includes the following steps:

[0062] S1. Preparation of iron tailings powder:

[0063] S1-1. A ball mill using steel balls as the grinding media is used for the first ball milling of crushed iron tailings to obtain a specific surface area of ​​166 m². 2 / kg iron tailings powder.

[0064] S1-2. The iron tailings powder obtained in step S1-1 is subjected to secondary grinding using a ball mill with a ball-to-material ratio of 6:1 at a speed of 240 r·min⁻¹. During the ball milling process, 0.03% sodium hexametaphosphate (by weight of the iron tailings powder) is added as a grinding aid; simultaneously, 1.5% silane coupling agent (by weight of the iron tailings powder) is added to modify the iron tailings powder during the second grinding process, resulting in a specific surface area of ​​636 m². 2 / kg of iron tailings powder.

[0065] The concrete preparation in step S2 and the concrete molding in step S3 of Example 2 are the same as those in Example 1.

[0066] Example 3

[0067] This embodiment provides a low-heat-of-hydration, high-volume iron tailings micro-powder concrete and its preparation method. The low-heat-of-hydration, high-volume iron tailings micro-powder concrete is made from the following raw material components by weight: 192 parts iron tailings micro-powder, 240 parts ordinary silicate cement, 48 parts slag powder, 794 parts manufactured sand, 932 parts stone, 154 parts water, and 11.5 parts admixture.

[0068] The preparation method includes the following steps:

[0069] S1. Preparation of iron tailings powder:

[0070] S1-1. A ball mill using steel balls as the grinding media is used for the first ball milling of crushed iron tailings to obtain a specific surface area of ​​163 m². 2 / kg iron tailings powder.

[0071] S1-2. The iron tailings powder obtained in step S1-1 is subjected to secondary grinding using a ball mill with a ball-to-material ratio of 8:1 at a speed of 240 r·min⁻¹. During the ball milling process, 0.15% (by weight of the iron tailings powder) of triethanolamine is added as a grinding aid; simultaneously, 2.0% (by weight of the iron tailings powder) of silane coupling agent is added to modify the iron tailings powder during the second grinding process, resulting in a specific surface area of ​​739 m². 2 / kg of iron tailings powder.

[0072] The concrete preparation in step S2 and the concrete molding in step S3 of Example 3 are the same as those in Example 1.

[0073] Comparative Example 1

[0074] This comparative example provides a concrete, which, by weight, is made from the following raw material components: 144 parts fly ash, 180 parts ordinary Portland cement, 36 parts slag powder, 914 parts manufactured sand, 913 parts aggregate, 173 parts water, and 8.6 parts admixture.

[0075] The difference between Comparative Example 1 and Example 1 is that the iron tailings powder in Example 1 is replaced with fly ash, and the preparation method is the same as in Example 1.

[0076] Comparative Example 2

[0077] This comparative example provides a concrete, which, by weight, is made from the following raw material components: 192 parts fly ash, 240 parts ordinary Portland cement, 48 parts slag powder, 794 parts manufactured sand, 932 parts aggregate, 154 parts water, and 11.5 parts admixture.

[0078] The difference between Comparative Example 2 and Example 3 is that the iron tailings powder in Example 1 is replaced with fly ash, and the preparation method is the same as in Example 3.

[0079] The heat of hydration of the cementitious materials in Examples 1-3 at 3 days of age was tested according to GB / T12959-2008 "Method for Determination of Heat of Hydration of Cement", and the results were as follows. Figure 1 The measurement results are shown.

[0080] Meanwhile, tests were conducted on Examples 1-3 and Comparative Examples 1-2 according to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", GB / T50080-2002 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", and GB50496-2018 "Standard for Construction of Mass Concrete", and the test results are shown in Table 2. The performance test results of the concrete prepared in each example and comparative example are shown in Table 1. Examples 1, 2, and 1 were all applied to C30 strength grade concrete, while Examples 3 and 2 were applied to C50 strength grade concrete.

[0081] Table 2 Performance Test Results

[0082]

[0083] Based on the test results in Table 2, combined with Figure 1 As can be seen, the low-heat-of-hydration, high-volume iron tailings micro-powder concrete prepared in this application meets all the requirements for physical and mechanical properties, and exhibits superior mechanical properties compared to the comparative example. Furthermore, the maximum adiabatic temperature rise of the low-heat-of-hydration, high-volume iron tailings micro-powder concrete prepared in this application meets the requirements of practical application specifications. The incorporation of a large amount of iron tailings micro-powder can reduce the adiabatic temperature rise of the concrete, effectively inhibiting the formation of temperature cracks in the concrete.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art can make various changes or equivalent substitutions to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention.

Claims

1. A method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete, characterized in that, Includes the following steps: S1. Preparation of iron tailings powder: Iron tailings were treated using a physical-chemical composite modification technique, firstly by ball milling to obtain a specific surface area ≥150 m². 2 / kg of iron tailings powder is then ball-milled a second time with the addition of grinding aids and silane coupling agents to obtain a fineness of ≤3% residue on a 45μm square-hole sieve and a specific surface area ≥500m². 2 / kg of iron tailings powder; S2. Concrete preparation: Weigh out the cementitious materials, sand, stone, water, and admixtures according to the mass fractions, and mix them evenly to obtain a concrete mixture; the cementitious materials include cement, slag powder, and the iron tailings powder obtained in step S1; In the cementitious material, the proportion of iron tailings powder is 40%, the proportion of cement is 50%, and the proportion of slag powder is 10%. S3, Concrete Forming: The concrete mixture obtained in step S2 is placed into a concrete adiabatic temperature rise test container, and temperature change data is collected in real time using computer control; at the same time, it is placed into a compressive strength test mold, and after 1 day, it is demolded and placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of more than 95% for curing until it reaches the corresponding age.

2. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 1, characterized in that, In step S1, the grinding aid includes any one or two of triethanolamine, stearic acid, and sodium hexametaphosphate.

3. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 2, characterized in that, Step S1 includes the following specific steps: S1-1. Perform a single ball milling on the iron tailings to obtain a specific surface area ≥150m². 2 / kg iron tailings powder: The crushed iron tailings were first ball-milled using a ball mill with steel balls as the grinding media, at a ball-to-material ratio of 2:1, to obtain a specific surface area ≥150 m². 2 / kg iron tailings powder; S1-2. Add grinding aid powder and perform secondary ball milling on the iron tailings powder, and add silane coupling agent to modify the iron tailings powder to obtain a specific surface area ≥500m². 2 / kg of iron tailings powder: The iron tailings powder obtained in step S1-1 was subjected to a second ball milling using steel balls as the grinding media, with a ball-to-material ratio of 3:1 to 10:

1. Grinding aids were added at 0.1% to 0.15% of the iron tailings powder mass; simultaneously, silane coupling agents at 1% to 3% of the iron tailings powder mass were added. During the second ball milling process, the iron tailings powder was modified to obtain a specific surface area ≥ 500 m². 2 / kg of iron tailings powder.

4. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 1, characterized in that, The low-heat-of-hydration, high-volume iron tailings micro-powder concrete comprises the following components by weight: 144-192 parts iron tailings micro-powder, 180-240 parts silicate cement, 36-48 parts slag powder, 794-914 parts sand, 913-932 parts stone, 154-173 parts water, and 8.6-11.5 parts admixture.

5. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 4, characterized in that, The slag powder is S95 ore powder with a specific surface area of ​​443 m². 2 / kg, fluidity ratio 98%, 28-day activity index 101%.

6. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 4, characterized in that, The cement is 42.5 ordinary Portland cement, with a 3-day heat of hydration of 226 J / g, a standard consistency water requirement of 26.8%, and a specific surface area of ​​410 m². 2 / kg.

7. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 4, characterized in that, The sand is calcareous manufactured sand with a fineness modulus of 2.7, an MB value of 0.75 g / kg, and a stone powder content of 2.6%; the stone is crushed stone with a continuous gradation of 5 mm to 20 mm, a mud powder content of 0.4%, and a porosity of 40%.

8. The method for preparing low-heat-of-hydration, high-volume iron tailings micro-powder concrete according to claim 4, characterized in that, The admixture is a retarded polycarboxylate superplasticizer with a water reduction rate of 30% and an initial setting time difference of +130 min.

9. A low-heat-of-hydration, high-volume iron tailings micro-powder concrete, characterized in that, The low-heat hydration, high-volume iron tailings micro-powder concrete is prepared by the preparation method described in any one of claims 1-8.

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