Artificial aggregate prepared by hydrothermal synthesis of iron tailings and preparation method and application thereof

Abstract

The present application belongs to the technical field of artificial aggregate preparation, and discloses a kind of artificial aggregate prepared by hydrothermal synthesis of iron tailings and a preparation method and application thereof.The artificial aggregate includes the following mass fractions of raw materials: 70-80 parts of iron tailings, 50-60 parts of bauxite, 30-50 parts of tungsten tailings, 25-40 parts of cementing material and 10-20 parts of activator.The process of three-stage grinding and hydrothermal synthesis makes the strength of the artificial aggregate reach a more excellent level.The cylinder compressive strength of the artificial aggregate obtained by the present application is 23.2-26.7 MPa, and the bulk density is 1200-1350 kg / m 3 The 28d compressive strength of the concrete prepared from the obtained artificial aggregate reaches 52.2-58.4 MPa, and the water absorption rate is 4.6-5.1%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial aggregate preparation, and particularly relates to an artificial aggregate prepared by hydrothermal synthesis of iron tailings and a preparation method and application thereof. BACKGROUND

[0002] With the development of the construction industry, the amount of concrete is increasing, which makes the demand for aggregate in the construction industry also increasing. Since the exploitation of natural aggregate will cause damage to the environment, the currently used construction aggregate is mostly artificial aggregate. Artificial aggregate concrete is one of high-performance concrete. Compared with ordinary cement concrete, artificial aggregate concrete not only can maintain its high strength and high durability, but also can improve the thermal insulation performance of concrete. However, since the strength of artificial aggregate is generally low, it becomes the main reason for limiting the development of the strength of artificial aggregate concrete.

[0003] Tailings slag is the residue after ore dressing or smelting, which belongs to a kind of solid waste. Large accumulation not only has an impact on the environment, but also causes waste of resources. Therefore, how to utilize the tailings slag, a kind of solid waste, has become a problem that needs to be considered in the field of ore dressing. Since the tailings slag contains a large amount of substances necessary for the cement hydration process, the preparation of high-strength aggregate for concrete using tailings slag has emerged. At present, various methods for preparing artificial aggregate from tailings slag have been developed, such as preparing artificial aggregate from molybdenum tailings, preparing artificial aggregate from iron tailings, and preparing artificial aggregate from slag.

[0004] Although various high-strength aggregates have been developed, a large amount of cementitious materials and fillers, such as fly ash, cement, silica fume, mineral powder and lime, need to be added during the preparation of artificial aggregate to improve the density and strength of artificial aggregate. The utilization rate of tailings slag is low, which is not conducive to the development of tailings slag recycling, and the strength of the final artificial aggregate cannot meet the needs of higher requirement concrete. Therefore, there is an urgent need in the field to develop an artificial aggregate with high utilization rate of tailings slag, without the need to add a large amount of cementitious materials, and excellent mechanical properties of the final aggregate. SUMMARY

[0005] The present application aims to provide an artificial aggregate prepared by hydrothermal synthesis of iron tailings and a preparation method and application thereof, to solve the problems of the existing artificial aggregate prepared from iron tailings, such as the need to add a large amount of cementitious materials, low utilization rate of tailings slag, and low strength of the obtained artificial aggregate, which cannot meet the application of higher requirement concrete.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] The application provides a kind of artificial aggregate prepared by hydrothermal synthesis of iron tailings, the artificial aggregate includes the following mass fraction of raw materials: iron tailings 70-80 parts, bauxite 50-60 parts, tungsten tailings 30-50 parts, cementing material 25-40 parts and activator 10-20 parts.

[0008] Preferably, the particle size of the iron tailings is 0.02-0.08 mm; the particle size of the bauxite is 0.8-1.25 mm; and the particle size of the tungsten tailings is 0.04-0.08 mm.

[0009] Preferably, the cementing material is cement and fly ash; and the mass ratio of cement to fly ash is 2-4:1.

[0010] Preferably, the activator is calcium hydroxide and water glass; the mass ratio of calcium hydroxide to water glass is 1:0.2-0.3; the modulus of the water glass is 2-3.5; and the mass concentration of the water glass is 10-30%.

[0011] The application further provides a method for preparing the artificial aggregate by hydrothermal synthesis of iron tailings, which comprises the following steps:

[0012] (1) grinding the iron tailings, bauxite, tungsten tailings and part of the cementing material in three stages to obtain a mixed powder;

[0013] (2) mixing the mixed powder and the activator, then adding the remaining cementing material to granulate, and finally sequentially performing pre-curing and hydrothermal synthesis to obtain the artificial aggregate.

[0014] Preferably, the mass of the part of the cementing material is 80-85% of the total mass of the cementing material.

[0015] Preferably, the specific steps of the three-stage grinding are as follows: grinding the iron tailings and tungsten tailings in the first stage to obtain a first mixed powder; grinding the first mixed powder and bauxite in the second stage to obtain a second mixed powder; and grinding the second mixed powder and part of the cementing material in the third stage to obtain the mixed powder.

[0016] Preferably, the time for the first-stage grinding and the third-stage grinding is independently 20-30 min; and the time for the second-stage grinding is 10-20 min.

[0017] Preferably, the temperature for the pre-curing is 20-25℃, the relative humidity for the pre-curing is 90-95%, and the time for the pre-curing is 24-48 h; the saturated vapor pressure for the hydrothermal synthesis is 1-1.5 MPa, the temperature for the hydrothermal synthesis is 180-200℃, and the time for the hydrothermal synthesis is 8-12 h.

[0018] The application further provides the application of the artificial aggregate prepared by hydrothermal synthesis of iron tailings in concrete.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] (1) The application uses iron tailings, bauxite and tungsten tailings as raw materials to prepare artificial aggregate, greatly saving resources, reducing the environmental pollution caused by the stacking of solid waste, and improving the utilization rate of solid waste;

[0021] (2) The cylinder compressive strength of the artificial aggregate obtained by the application is 23.2-26.7 MPa, and the bulk density is 1200-1350 kg / m 3 ; the 28d compressive strength of the concrete prepared from the artificial aggregate reaches 52.2-58.4 MPa, and the water absorption rate is 4.6-5.1%; the artificial aggregate obtained by the application can reach a higher strength and can meet the application of higher requirement concrete;

[0022] (3) The application uses reasonable proportioning of raw materials and particle sizes, combined with a three-stage grinding and hydrothermal synthesis process, so that the strength of the artificial aggregate reaches a more excellent level; the preparation process is simple, the preparation raw materials are simple and easy to obtain, meets the development direction of green environmental protection, and is suitable for large-scale development and utilization. DETAILED DESCRIPTION

[0023] The application provides artificial aggregate prepared by hydrothermal synthesis using iron tailings, and the artificial aggregate comprises the following raw materials in mass fraction: 70-80 parts of iron tailings, 50-60 parts of bauxite, 30-50 parts of tungsten tailings, 25-40 parts of cementing material and 10-20 parts of activator.

[0024] In the application, the amount of the iron tailings is preferably 72-78 parts, and further preferably 75-76 parts; the amount of the bauxite is preferably 53-58 parts, and further preferably 54-56 parts; the amount of the tungsten tailings is preferably 40-45 parts, and further preferably 42-44 parts; the amount of the cementing material is preferably 30-38 parts, and further preferably 35-36 parts; and the amount of the activator is preferably 12-18 parts, and further preferably 15-17 parts.

[0025] In the application, the particle size of the iron tailings is preferably 0.02-0.08 mm, and further preferably 0.03-0.06 mm; the particle size of the bauxite is preferably 0.8-1.25 mm, and further preferably 0.9-1.2 mm; and the particle size of the tungsten tailings is preferably 0.04-0.08 mm, and further preferably 0.05-0.06 mm.

[0026] In the present application, the cementing material is preferably cement and fly ash; the mass ratio of cement and fly ash is preferably 2-4:1, further preferably 3:1; the particle size of fly ash is preferably 60-120 mesh, further preferably 80-100 mesh.

[0027] In the present application, the activator is preferably calcium hydroxide and water glass; the mass ratio of calcium hydroxide and water glass is preferably 1:0.2-0.3, further preferably 1:0.25; the modulus of water glass is preferably 2-3.5, further preferably 2.5-3; the mass concentration of water glass is preferably 10-30%, further preferably 20-25%.

[0028] In the present application, the calcium-silicon ratio of the artificial aggregate is preferably 0.825-0.835, further preferably 0.833.

[0029] The present application also provides a method for preparing artificial aggregate by hydrothermal synthesis of iron tailings, comprising the following steps:

[0030] (1) grinding the iron tailings, bauxite, tungsten tailings and part of the cementing material in three stages to obtain a mixed powder;

[0031] (2) mixing the mixed powder and the activator, then adding the remaining cementing material for granulation, and finally sequentially pre-curing and hydrothermal synthesis to obtain the artificial aggregate.

[0032] In the present application, the mass of the part of the cementing material is preferably 80-85% of the total mass of the cementing material, further preferably 82-83% of the total mass of the cementing material.

[0033] In the present application, the specific steps of the three-stage grinding are as follows: grinding the iron tailings and tungsten tailings in the first stage to obtain a first mixed powder; grinding the first mixed powder and bauxite in the second stage to obtain a second mixed powder; and grinding the second mixed powder and part of the cementing material in the third stage to obtain the mixed powder.

[0034] In the present application, the time of the first-stage grinding and the third-stage grinding is independently preferably 20-30 min, further preferably 22-28 min; and the time of the second-stage grinding is preferably 10-20 min, further preferably 15-18 min.

[0035] In the present application, the three-stage grinding is carried out in a ball mill; the medium for the three-stage grinding is ceramic balls; and the particle size of the ceramic balls is preferably 5-8 mm, further preferably 6-7 mm.

[0036] In the present application, the specific step of the granulation is that: the mixed material of the mixed powder and the activator is placed in a disc balling machine to form aggregate ball cores by spraying water while rolling; then the remaining cementitious material is added to continue rolling until the surface of the aggregate ball core is completely wrapped by the cementitious material particles and the shell is smooth without bonding between the ball cores, that is, the granulation is completed; the water usage is preferably 15-20% of the total usage of each raw material, and further preferably 16-18% of the total usage of each raw material; the particle size of the aggregate ball core is preferably 1-3mm, and further preferably 1.5-2.5mm.

[0037] In the present application, the temperature of the pre-curing is preferably 20-25℃, and further preferably 22-24℃; the relative humidity of the pre-curing is preferably 90-95%, and further preferably 92-94%; the time of the pre-curing is preferably 24-48h, and further preferably 30-35h; the saturated vapor pressure of the hydrothermal synthesis is preferably 1-1.5MPa, and further preferably 1.2-1.4MPa; the temperature of the hydrothermal synthesis is preferably 180-200℃, and further preferably 185-195℃; the time of the hydrothermal synthesis is preferably 8-12h, and further preferably 9-10h.

[0038] The present application uses three kinds of tailings slag of iron tailings, bauxite and tungsten tailings as raw materials for preparing artificial aggregate, which can greatly save resources, reduce the pollution of solid waste to the environment and improve the utilization rate of solid waste. Among them, the bauxite and tungsten tailings contain SiO2, which can solve the problem of low silicon content in iron tailings; the bauxite is composed of Al(OH)3, NaFe(SO4)2(OH)6 and SiO2, and the reaction of aluminum and silicon with some components in the cement hydration products can generate some complex compounds (such as hydrated calcium aluminate series products and hydrated calcium silicate series products, etc.), which fill the pores of the cement and form a relatively dense structure, thereby improving the strength of the obtained artificial aggregate; after grinding, the specific surface area of the tungsten tailings increases and part of the weak areas in the crystal structure is destroyed, which improves the full contact of tungsten tailings particles with the activator and the dissolution of soluble Si and Al; grinding improves the activity of tungsten tailings, which enhances the ability of the tungsten tailings to form a gel phase matrix under the action of the activator, further improving the compressive strength of the obtained artificial aggregate. In addition, the present application reasonably configures the particle size of the iron tailings, bauxite and tungsten tailings, and the cement, fly ash and relatively large particle size bauxite can be used as "grinding balls" for the iron tailings in the grinding process, so that part of the particle size of the iron tailings reaches the micron level, which can improve the activity of the iron tailings and further improve the strength of the obtained artificial aggregate; the present application uses the synergistic effect of each raw material to obtain a raw material ratio of calcium silicon ratio of 0.825-0.835, which can ensure that the tobermorite structure is obtained by hydrothermal synthesis, further improving the strength and durability of the obtained artificial aggregate.

[0039] The application further provides application of the artificial aggregate prepared by the hydrothermal synthesis of the iron tailings in concrete.

[0040] The technical solutions provided by the application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the application.

[0041] The mineral composition and content of the iron tailings used in the following examples are as follows: quartz 60%, calcite 3%, dolomite 8%, amphibole 10%, chlorite 9%, mica 9%, and the rest are impurities; the mineral composition and content of the tungsten tailings are as follows: quartz 27%, calcite 26%, grossular 37%, amphibole 5%, chlorite 5%, and the rest are impurities; the composition and ratio of the bauxite are as follows: Al2O3 75%, SiO2 10%, Fe2O3 10%, TiO2 2%, MgO 0.05%, K2O 0.06%, Na2O 0.03%, MnO2 0.02%, and the rest are organic matter and carbon.

[0042] Example 1

[0043] The raw materials and their amounts used in this example are as follows:

[0044] 78 parts of iron tailings with a particle size of 0.06 mm, 60 parts of bauxite with a particle size of 1.2 mm, 30 parts of tungsten tailings with a particle size of 0.05 mm, 42.520 parts of ordinary Portland cement P.O, 5 parts of fly ash with a particle size of 80 mesh, 16 parts of calcium hydroxide, 4 parts of water glass with a modulus of 2.5 and a mass concentration of 20%;

[0045] The total calcium-silicon ratio of the above raw materials is 0.833;

[0046] The preparation process is as follows:

[0047] The cement and fly ash in the above mass parts are mixed to obtain a cementitious material;

[0048] The iron tailings and tungsten tailings are placed in a ball mill (with ceramic balls with a particle size of 7 mm) and ground for 20 min, then the bauxite is added and ground for another 15 min, and finally 80% of the total amount of cementitious material is added and ground for 20 min to obtain a mixed powder;

[0049] The mixed powder, calcium hydroxide and water glass are mixed and placed in a disc-type balling machine, and water is sprayed while rolling to form aggregate core with a particle size of 1.5 mm; then the remaining cementitious material is added and continues to roll until the surface of the aggregate core is completely wrapped by the cementitious material particles and the shell is smooth and there is no bonding between the cores, i.e. the granulation is completed;

[0050] The granulated ball material is first pre-cured for 24 hours in an environment with a temperature of 25°C and a relative humidity of 95%, and then is placed in an autoclave for hydrothermal synthesis for 10 hours under conditions of a saturated steam pressure of 1.2 MPa and a temperature of 180°C. After the hydrothermal synthesis is completed, the obtained product is cooled in the furnace for 3 hours, and then is taken out and air-cooled to room temperature to obtain the artificial aggregate.

[0051] According to GB / T 17431.1-2010 "Lightweight Aggregate and Its Test Methods Part 1: Lightweight Aggregate", the performance of the artificial aggregate obtained in this example is tested, and the test results are as follows: bulk density 1250 kg / m 3 , cylinder compressive strength 23.2 MPa.

[0052] Example 2

[0053] The raw materials used in this example and their amounts are as follows:

[0054] 75 parts of iron tailings with a particle size of 0.08 mm, 58 parts of bauxite with a particle size of 1.2 mm, 40 parts of tungsten tailings with a particle size of 0.05 mm, 42.520 parts of ordinary Portland cement P.O, 5 parts of fly ash with a particle size of 80 mesh, 16 parts of calcium hydroxide, 4 parts of water glass with a modulus of 2.5 and a mass concentration of 10%;

[0055] The total calcium-silicon ratio of the above raw materials is 0.833;

[0056] The preparation process is as follows:

[0057] Mix the cement and fly ash in the above mass fractions to obtain a cementitious material;

[0058] Put the iron tailings and tungsten tailings into a ball mill (with ceramic balls with a particle size of 7 mm) and grind for 22 minutes, then add bauxite to continue grinding for 10 minutes, and finally add 85% of the total amount of cementitious material to grind for 28 minutes to obtain a mixed powder;

[0059] Mix the mixed powder, calcium hydroxide and water glass, and place them in a disc-type balling machine to form aggregate ball cores with a particle size of 1.5 mm by rolling and spraying water. Then add the remaining cementitious material to continue rolling until the surface of the aggregate ball cores is completely wrapped by the cementitious material particles and the shell is smooth without sticking between the ball cores, i.e. the granulation is completed.

[0060] The granulated ball material is first pre-cured for 24 hours in an environment with a temperature of 25°C and a relative humidity of 95%, and then is placed in an autoclave for hydrothermal synthesis for 10 hours under conditions of a saturated steam pressure of 1.2 MPa and a temperature of 180°C. After the hydrothermal synthesis is completed, the obtained product is cooled in the furnace for 3 hours, and then is taken out and air-cooled to room temperature to obtain the artificial aggregate.

[0061] According to GB / T17431.1-2010 "Lightweight Aggregate and Its Test Methods Part 1: Lightweight Aggregate", the performance test of the artificial aggregate obtained in this example is carried out, and the test results are as follows: bulk density 1200 kg / m 3 , cylinder strength 25.2 MPa.

[0062] Example 3

[0063] The raw materials used in this example and their amounts are as follows:

[0064] 76 parts of iron tailings with a particle size of 0.06 mm, 58 parts of bauxite with a particle size of 0.9 mm, 45 parts of tungsten tailings with a particle size of 0.08 mm, 42.524 parts of ordinary Portland cement P.O, 6 parts of fly ash with a particle size of 100 mesh, 16 parts of calcium hydroxide, 4 parts of water glass with a modulus of 2 and a mass concentration of 25%;

[0065] The total calcium-silicon ratio of the above raw materials is 0.833;

[0066] The preparation process is as follows:

[0067] Mix the cement and fly ash in the above mass fractions to obtain a cementitious material;

[0068] Put the iron tailings and tungsten tailings into a ball mill (with ceramic balls with a particle size of 7 mm inside) and grind for 22 min, then add bauxite to continue grinding for 15 min, and finally add 83% of the total amount of cementitious material to grind for 30 min to obtain a mixed powder;

[0069] Mix the mixed powder, calcium hydroxide and water glass, and put them into a disc-type balling machine to roll and spray water at the same time to form aggregate ball cores with a particle size of 2.5 mm; then add the remaining cementitious material to continue rolling until the surface of the aggregate ball core is completely wrapped by the cementitious material particles and the shell is smooth, and there is no bonding between the ball cores, i.e. the granulation is completed;

[0070] Put the granulated ball material into a pre-conservation environment at 25°C and a relative humidity of 92% for 24h, then put it into a steam autoclave for hydrothermal synthesis under the conditions of a saturated steam pressure of 1.4 MPa and a temperature of 195°C for 9h, and then cool the obtained product in the furnace for 3h, and then take it out and cool it to room temperature to obtain artificial aggregate.

[0071] According to GB / T17431.1-2010 "Lightweight Aggregate and Its Test Methods Part 1: Lightweight Aggregate", the performance test of the artificial aggregate obtained in this example is carried out, and the test results are as follows: bulk density 1285 kg / m 3 , cylinder strength 26.7 MPa.

[0072] Example 4

[0073] The raw materials and their amounts used in this example are as follows:

[0074] 75 parts of iron tailings with a particle size of 0.08 mm, 56 parts of bauxite with a particle size of 0.8 mm, 42 parts of tungsten tailings with a particle size of 0.06 mm, 42.524 parts of ordinary Portland cement P.O 42, 6 parts of fly ash with a particle size of 60 mesh, 16 parts of calcium hydroxide, 4 parts of water glass with a modulus of 2.5 and a mass concentration of 25%;

[0075] The total calcium-silicon ratio of the above raw materials is 0.833;

[0076] The preparation process is as follows:

[0077] Mix the cement and fly ash in the above mass fractions to obtain a cementitious material;

[0078] Put the iron tailings and tungsten tailings into a ball mill (with ceramic balls with a particle size of 7 mm inside) and grind for 20 min, then add bauxite to continue grinding for 20 min, and finally add 82% of the total amount of cementitious material to grind for 20 min to obtain a mixed powder;

[0079] Mix the mixed powder, calcium hydroxide and water glass, and place them in a disc-type balling machine, while rolling and spraying water to form aggregate ball cores with a particle size of 2.5 mm; then add the remaining cementitious material and continue rolling until the surface of the aggregate ball cores is completely covered with cementitious material particles and the shell is smooth without sticking between the ball cores, i.e. the granulation is completed;

[0080] The granulated ball material obtained is first pre-cured for 24 h in an environment with a temperature of 25°C and a relative humidity of 94%, then placed in an autoclave for hydrothermal synthesis under a saturated steam pressure of 1.5 MPa and a temperature of 180°C for 12 h, and after the hydrothermal synthesis is completed, the obtained product is cooled in the furnace for 3 h, then taken out and air-cooled to room temperature to obtain artificial aggregate.

[0081] According to GB / T17431.1-2010 "Lightweight Aggregate and Its Test Methods Part 1: Lightweight Aggregate", the performance of the artificial aggregate obtained in this example is tested, and the test results are as follows: bulk density 1350 kg / m 3 , cylinder compressive strength 26.5 MPa.

[0082] Application Example 1

[0083] The artificial aggregate obtained in Examples 1-4 is used in concrete, respectively, denoted as experimental groups 1-4, and a control group is set; the experimental groups and the control group are prepared according to the standard of C40 concrete; wherein the sand in the experimental groups is completely replaced by an equal amount of artificial aggregate obtained in Examples 1-4. The preparation of C40 concrete is as follows: ordinary Portland cement P.O 42.5420 kg / m 3sand (particle size 0.25-0.35mm, fineness modulus 1.8) 570kg / m 3 stone (particle size and gradation: 3-5mm 5%, 6mm-10mm 35%, 11mm-15mm 35%, 16mm-20mm 15%, 21-25mm 10%) 1273kg / m 3 water 170kg / m 3 PCE-101 polycarboxylate superplasticizer (mass concentration 10%) 4g. After completion, the properties of the concrete obtained in experimental groups 1-4 and the control group were determined. The results are shown in Table 1.

[0084] Table 1 Properties of concrete obtained in experimental groups 1-4 and the control group

[0085]

[0086] As shown in Table 1, the 28d compressive strength of the concrete prepared using the artificial aggregate obtained in the application is 52.2-58.4MPa, and the water absorption is 4.6-5.1%. The artificial aggregate obtained in the application can achieve a higher strength, and can satisfy the application of higher requirement concrete.

[0087] The above description is only preferred embodiments of the application, and it should be pointed out that, for those skilled in the art, without departing from the principles of the application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. An artificial aggregate prepared by hydrothermal synthesis using iron tailings, characterized in that, The artificial aggregate comprises the following raw materials in parts by weight: 70-80 parts iron tailings, 50-60 parts bauxite, 30-50 parts tungsten tailings, 25-40 parts cementing material, and 10-20 parts activator. The iron tailings have a particle size of 0.02–0.08 mm; the bauxite has a particle size of 0.8–1.25 mm; and the tungsten tailings have a particle size of 0.04–0.08 mm. The calcium-to-silicon ratio of the raw material is 0.825~0.835, and the tobermorite structure is obtained after hydrothermal synthesis.

2. The artificial aggregate prepared by hydrothermal synthesis of iron tailings according to claim 1, characterized in that, The cementitious material is cement and fly ash; the mass ratio of cement to fly ash is 2 to 4:

1.

3. The artificial aggregate prepared by hydrothermal synthesis of iron tailings according to claim 1 or 2, characterized in that, The activator is calcium hydroxide and water glass; the mass ratio of calcium hydroxide to water glass is 1:0.2-0.3; the modulus of water glass is 2-3.5, and the mass concentration of water glass is 10-30%.

4. The method for preparing artificial aggregates using hydrothermal synthesis of iron tailings as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Iron tailings, bauxite, tungsten tailings and some cementitious materials are ground in three stages to obtain mixed powder; (2) Mix the mixed powder and activator, then add the remaining cementitious material for granulation, and finally pre-curing and hydrothermal synthesis to obtain artificial aggregate.

5. The method for preparing artificial aggregates using hydrothermal synthesis of iron tailings according to claim 4, characterized in that, The mass of the cementitious material is 80-85% of the total mass of the cementitious material.

6. The method for preparing artificial aggregates using hydrothermal synthesis of iron tailings according to claim 5, characterized in that, The specific steps of the three-stage grinding are as follows: the iron tailings and tungsten tailings are ground in the first stage to obtain the first mixed powder; The first mixed powder and bauxite are subjected to a second-stage grinding to obtain a second mixed powder; The second mixed powder and part of the cementitious material are subjected to a third-stage grinding to obtain a mixed powder.

7. The method for preparing artificial aggregates using hydrothermal synthesis of iron tailings according to claim 6, characterized in that, The grinding time for the first and third stages is 20-30 minutes, which is independent; the grinding time for the second stage is 10-20 minutes.

8. The method for preparing artificial aggregates using hydrothermal synthesis of iron tailings according to claim 7, characterized in that, The pre-curing temperature is 20–25°C, the relative humidity is 90–95%, and the pre-curing time is 24–48 h; the saturated vapor pressure of the hydrothermal synthesis is 1–1.5 MPa, the hydrothermal synthesis temperature is 180–200°C, and the hydrothermal synthesis time is 8–12 h.

9. The application of the artificial aggregate prepared by hydrothermal synthesis of iron tailings as described in any one of claims 1 to 3 in concrete.

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