Coal gangue-based spherical multi-element composite material for coal mine filling and preparation method thereof

Abstract

The application provides a coal gangue-based spherical multi-element composite material for coal mine filling and a preparation method thereof. The material comprises A component and B component. The A component is prepared from coal gangue, clay, glutinous rice powder, a binder and water as raw materials. The B component is prepared from cementitious material, a retarder, lime and water as raw materials. The application fills the two traditional filling materials, i.e. coal gangue and clay, after granulation, discards the traditional powder filling mode, utilizes the low friction and good fluidity of the material after being formed into a ball to promote the filling aggregate conveying, fills the cement slurry and the aggregate separately, and fully avoids the pipeline blockage caused by the aggregate accumulation or local coagulation. The separate pipeline operation is easier to repair and dredge the local blockage.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mine backfill materials, and relates to coal gangue-based composite materials, specifically to a coal gangue-based spherical multi-component composite material for coal mine backfilling and its preparation method. Background Technology

[0002] Coal gangue, a major byproduct of coal sorting, exists in massive quantities and continues to increase annually. It not only occupies significant land resources but also pollutes soil, surface water, and groundwater. Therefore, the green disposal of coal gangue is a necessary development direction for the coal industry. Currently, backfilling mining has gained attention in order to achieve the goal of intelligent and green mining. Backfilling mining is suitable for most mineral deposit environments, offering high safety and recovery rates during the mining process, while effectively preventing disasters such as roof falls and fires. Coal mining creates underground cavities, leading to a series of problems such as surface subsidence and ecological damage. Backfilling these goafs requires a large amount of material; therefore, using coal gangue as a backfill material is a highly efficient and low-cost mine backfilling technology that achieves both green disposal of coal gangue and the goal of green coal mining—taking from the mine and using it back into the mine.

[0003] However, underground backfilling also presents some problems, such as low backfilling efficiency, high cost, poor strength, or underground pollution due to improper selection of backfilling materials; pipe blockage caused by improper layout of backfilling pipelines; and effective coordination between mining and backfilling. Among these, the most significant issue is pipe blockage in backfilling pipelines. The main causes of this problem include: first, excessively thick slurry results in low flow velocity at bends, leading to localized blockage; second, the slurry's coagulation and sedimentation during natural flow accumulates over time, narrowing the pipeline and causing blockage; and third, the presence of large particles or impurities in the pipeline can also cause blockage.

[0004] Currently, there are two main solutions to the pipe blockage problem: one is to optimize the pipeline design, but optimizing the pipeline structure cannot fundamentally alleviate the blockage problem; the other is to improve the filling material transported by the pipeline. If the fluidity and solidification properties of the filling material can be improved, it is expected to fundamentally alleviate the blockage problem. Summary of the Invention

[0005] In view of the defects and deficiencies of the existing technology, the purpose of this invention is to provide a coal gangue-based spherical multi-component composite material for coal mine backfilling and its preparation method, thereby solving the technical problem that the insufficient fluidity and solidification properties of coal mine backfilling materials in the existing technology lead to easy blockage of pipelines.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B.

[0008] The A component is made from coal gangue, clay, glutinous rice flour, binder and water. The mass ratio of coal gangue, clay, glutinous rice flour, binder and water is (50-80):(10-40):(5-20):(2-8):(20-40).

[0009] Component B is made from cementitious materials, retarder, lime and water as raw materials, and the mass ratio of cementitious materials, retarder, lime and water is (50-80):(10-40):(2-20):(100-150).

[0010] The present invention also has the following technical features:

[0011] Preferably, the mass ratio of the coal gangue, clay, glutinous rice flour, binder and water is (60-70):(15-30):10:5:(25-30); the mass ratio of the cementitious material, retarder, lime and water is (65-70):(20-25):(5-15):(120-130).

[0012] Specifically, the adhesive is water glass.

[0013] Specifically, the cementing material is selected from one or more of silicate cement and sulfoaluminate cement.

[0014] Specifically, the retarder is gypsum.

[0015] This invention also protects a method for preparing the coal gangue-based spherical multi-component composite material for coal mine backfilling as described above, the method specifically including the following steps:

[0016] Step 1, Prepare component A:

[0017] Step 1.1, coal gangue crushing.

[0018] Step 1.2, Ingredients: Mix glutinous rice flour and clay in advance to form a mixture, and then put it into the ball-making machine.

[0019] Step 1.3, Screening: After mixing the crushed coal gangue with the uncrushed coal gangue raw material, the mixture is screened into five groups according to the particle size range of 0-10mm, 10-20mm, 20-30mm, 30-40mm and 40-50mm through a grading screen. The five groups of coal gangue are then fed into a pelletizing machine containing the mixture.

[0020] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution.

[0021] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as the mother balls, and the mixed material is continuously bonded together during the downward rolling process to increase the size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm screens. When the amount of material passing through the screen is ≤10%, the pelletizing process ends, and coal gangue pellets are obtained.

[0022] Step 1.6, Curing.

[0023] Step 1.7, Sorting: The solidified coal gangue pellets are divided into five groups according to the particle size ranges of ≤10mm, 10~25mm, 25~40mm, 40~55mm and ≥55mm.

[0024] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio. The mass ratio of the first group, the second group, the third group, the fourth group and the fifth group is 10:20:40:20:10. The coal gangue pellets after gradation are the A component.

[0025] Step 2, Preparation of Component B: Component B is prepared by mixing cementitious materials, gypsum, lime and water.

[0026] Specifically, step 1.1 is as follows: after the coal gangue raw material leaves the factory for initial screening, the large pieces of coal gangue with a particle size ≥ 50mm are crushed and crushed coal gangue is obtained from the discharge port. The particle size of the crushed coal gangue is ≤ 30mm.

[0027] Specifically, in step 1.4, the spray flow rate is 1.5 to 1.6 L / h.

[0028] Specifically, in step 1.5, the baller is tilted at 35° and rotated at 15 r / min.

[0029] Specifically, step 1.6 is as follows: place the five groups of coal gangue pellets in an environment of 25±5℃ and 30% relative humidity for natural curing for 3 days, and the curing is completed.

[0030] The beneficial technical effects of this invention compared to the prior art are as follows:

[0031] (I) This invention uses coal gangue and clay, two traditional backfill materials, for backfilling after granulation, abandoning the traditional powder backfilling method. It utilizes the low friction and good fluidity of the materials after they are granulated to promote the transport of backfill aggregate. At the same time, the cement slurry and aggregate are filled separately, which fully avoids pipeline blockage caused by aggregate accumulation or local solidification. Separate pipeline operation makes it easier to repair and clear local blockages.

[0032] (II) The present invention uses coal gangue as backfill material, which meets the requirements of green mine development. The clay and glutinous rice flour used as filler aggregates are non-toxic and harmless to the environment.

[0033] (III) The clay and glutinous rice flour materials used in this invention are inexpensive, readily available, and abundant. The coal gangue comes from mining byproducts in filling mining areas, taking from the mine and using it in the mine. At the same time, the adhesive properties of glutinous rice flour, combined with water glass and lime, can save on cement usage and further reduce the final production cost. Attached Figure Description

[0034] Figure 1 A schematic flowchart illustrating the preparation method of coal gangue-based spherical multi-component composite materials for coal mine backfilling.

[0035] The technical solution of the present invention will be further described below with reference to the embodiments. Detailed Implementation

[0036] This invention first involves mixing component A according to a specified ratio to form spheres. Component A includes coal gangue, clay, glutinous rice flour, water glass, and water. The coal gangue particles themselves serve as the "mother spheres" in the sphere-making process. During sphere-making, clay and glutinous rice flour adhere to the "mother spheres," helping to transform irregular coal gangue particles into more regular spherical shapes. Simultaneously, glutinous rice flour also increases the adhesion between the powder and the mother sphere. Water glass is a commonly used adhesive in industry. After preparing a water glass solution with water, it is sprayed during the sphere-making process to enhance the adhesion between the clay, glutinous rice flour, and coal gangue.

[0037] Component B is a slurry made from cementitious materials, gypsum, lime, and water. It is used to fill and solidify the granules of Component A. The cementitious materials are mainly various types of cement. After reacting with water, they provide the main bonding effect under different construction conditions and provide overall strength. Gypsum is a commonly used retarder to adjust the setting time of the slurry. Lime can be mixed with cementitious materials to reduce costs while improving overall strength and hardness. At the same time, its interaction with glutinous rice flour and water can further increase adhesion and strength.

[0038] It should be noted that all raw materials used in the preparation of this invention, unless otherwise specified, are known in the art. For example, the silicate cement used is conventional silicate cement known in the prior art, preferably grade 42.5 silicate cement. The sulfoaluminate cement used is conventional silicate cement known in the prior art, preferably grade 42.5 sulfoaluminate cement.

[0039] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0040] Example 1:

[0041] This embodiment provides a coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B. Component A is made from coal gangue, clay, glutinous rice flour, water glass, and water, wherein the mass ratio of coal gangue:clay:glutinous rice flour:water glass:water is 60:30:10:5:30. Component B is made from cementitious materials, gypsum, lime, and water, wherein the cementitious material is silicate cement, and the mass ratio of cementitious material:gypsum:lime:water is 65:20:15:120.

[0042] In this embodiment, the preparation method of the coal gangue-based spherical multi-component composite material for coal mine backfilling specifically includes the following steps:

[0043] Step 1: Preparation of Component A (Component A is prepared according to the process flow of "gangue crushing - screening - batching - additives - pelletizing - solidification - sorting - gradation"):

[0044] Step 1.1, Coal gangue crushing: After the initial screening of the coal gangue raw material at the factory, the large pieces of coal gangue with a particle size ≥ 50mm are crushed by a PE150×250 jaw crusher to obtain crushed coal gangue from the discharge port. The particle size of the crushed coal gangue is ≤ 30mm.

[0045] Step 1.2, Ingredients: Mix glutinous rice flour and clay in advance to form a mixture, and then put it into the ball-making machine.

[0046] Step 1.3, Screening: After mixing the crushed coal gangue with the uncrushed coal gangue raw material, the mixture is screened into 5 groups according to the particle size range of 0-10mm, 10-20mm, 20-30mm, 30-40mm and 40-50mm through a grading screen. The 5 groups of coal gangue are then fed into a pelletizer containing the mixture.

[0047] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution, wherein the mass ratio of water glass to water is 1:6, and the spraying flow rate is 1.5L / h.

[0048] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as "mother balls," and their size is increased by continuously binding the mixed material as they roll downwards. The pelletizing machine has an inclination angle of 35° and a rotation speed of 15 r / min. The proportion of coal gangue balls produced is 120% of its own particle size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm screens. Pelletizing ends when the amount undersized is ≤10%, and coal gangue pellets are obtained.

[0049] Step 1.6, Curing: Place the 5 groups of coal gangue pellets in an environment of 25±5℃ and 30% relative humidity for natural curing for 3 days. At this time, there is no obvious moisture residue on the surface of the pellets, and the curing is completed.

[0050] Step 1.7, Sorting: The solidified coal gangue pellets are divided into five groups, A, B, C, D, and E, according to the particle size ranges of ≤10mm, 10~25mm, 25~40mm, 40~55mm, and ≥55mm.

[0051] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio, with the ratio of groups A, B, C, D, and E being 10:20:40:20:10. The coal gangue pellets after gradation are the A component, and their natural packing void ratio is 13%.

[0052] Step 2, Preparation of Component B: Mix the cementitious material, gypsum, lime and water to obtain a mixed slurry, which is Component B; Test Component B and determine that the setting time of Component B is 195 min and the fluidity is 330 mm.

[0053] Verification of the effect of Example 1:

[0054] In this embodiment, component A obtained in step one is filled into a designated area, and another pipeline is laid to simultaneously inject component B obtained in step two into the filling area, thus obtaining a sample filled with coal gangue-based spherical multi-component composite material; then, the sample filled with coal gangue-based spherical multi-component composite material is tested according to the standard method of "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107—2010), and the 1-day compressive strength of the sample is finally determined to be 9.3 MPa.

[0055] Example 2:

[0056] This embodiment provides a coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B. Component A is made from coal gangue, clay, glutinous rice flour, water glass, and water, wherein the mass ratio of coal gangue:clay:glutinous rice flour:water glass:water is 75:15:10:6:30. Component B is made from cementitious materials, gypsum, lime, and water. The cementitious materials are silicate cement and sulfoaluminate cement, wherein the mass ratio of silicate cement to sulfoaluminate cement is 2:1, and the mass ratio of cementitious materials:gypsum:lime:water is 70:25:5:130.

[0057] In this embodiment, the preparation method of the coal gangue-based spherical multi-component composite material for coal mine backfilling specifically includes the following steps:

[0058] Step 1, Prepare component A:

[0059] Step 1.1, Coal gangue crushing: After the initial screening of the coal gangue raw material at the factory, the large pieces of coal gangue with a particle size ≥ 50mm are crushed by a PEY300×900 hydraulic jaw crusher to obtain crushed coal gangue from the discharge port. The particle size of the crushed coal gangue is ≤ 25mm.

[0060] Steps 1.2 and 1.3 in this embodiment are the same as steps 1.2 and 1.3 in embodiment 1.

[0061] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution, wherein the mass ratio of water glass to water is 1:5, and the spraying flow rate is 1.6L / h.

[0062] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as "mother balls," and their size is increased by continuously binding the mixed material as they roll downwards. The pelletizing machine has an inclination angle of 30° and a rotation speed of 12 r / min. The proportion of coal gangue balls produced is 115% of its own particle size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm screens. Pelletizing ends when the amount undersized is ≤10%, and coal gangue pellets are obtained.

[0063] Steps 1.6 and 1.7 in this embodiment are the same as steps 1.6 and 1.7 in embodiment 1.

[0064] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio, with the ratio of groups A, B, C, D, and E being 5:20:50:20:5. The coal gangue pellets after gradation are the A component, and their natural packing void ratio is 22%.

[0065] Step 2, Preparation of Component B: The cementitious material, gypsum, lime and water are mixed to prepare a mixed slurry, which is Component B; Component B is tested and the setting time is determined to be 188 min and the fluidity is 269 mm.

[0066] Verification of the effect of Example 2:

[0067] In this embodiment, component A obtained in step one is filled into a designated area, and another pipeline is laid to simultaneously inject component B obtained in step two into the filling area, thus obtaining a sample filled with coal gangue-based spherical multi-component composite material; then, the sample filled with coal gangue-based spherical multi-component composite material is tested according to the standard method of "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107—2010), and the 1-day compressive strength of the sample is finally determined to be 5.1 MPa.

[0068] Example 3:

[0069] This embodiment provides a coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B. Component A is made from coal gangue, clay, glutinous rice flour, water glass, and water, wherein the mass ratio of coal gangue:clay:glutinous rice flour:water glass:water is 65:25:10:5:30. Component B is made from cementitious material, gypsum, lime, and water, wherein the cementitious material is silicate cement, and the mass ratio of cementitious material:gypsum:lime:water is 65:25:10:120.

[0070] In this embodiment, the preparation method of the coal gangue-based spherical multi-component composite material for coal mine backfilling specifically includes the following steps:

[0071] Step 1: Preparation of Component A (Component A is prepared according to the process flow of "gangue crushing - screening - batching - additives - pelletizing - solidification - sorting - gradation"):

[0072] Step 1.1, Coal gangue crushing: After the initial screening of the coal gangue raw material at the factory, the large pieces of coal gangue with a particle size ≥ 50mm are crushed by a PEY300×900 hydraulic jaw crusher to obtain crushed coal gangue from the discharge port. The particle size of the crushed coal gangue is ≤ 30mm.

[0073] Steps 1.2 and 1.3 in this embodiment are the same as steps 1.2 and 1.3 in embodiment 1.

[0074] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution, wherein the mass ratio of water glass to water is 1:6, and the spray flow rate is 1.6L / h.

[0075] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as "mother balls," and their size is increased by continuously binding the mixed material as they roll downwards. The pelletizing machine has an inclination angle of 30° and a rotation speed of 12 r / min. The proportion of coal gangue balls produced is 115% of its own particle size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm screens. Pelletizing ends when the amount undersized is ≤10%, and coal gangue pellets are obtained.

[0076] Steps 1.6 and 1.7 in this embodiment are the same as steps 1.6 and 1.7 in embodiment 1.

[0077] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio, with the ratio of groups A, B, C, D, and E being 5:20:50:20:5. The coal gangue pellets after gradation are the A component, and their natural packing void ratio is 15%.

[0078] Step 2, Preparation of Component B: The cementitious material, gypsum, lime and water are mixed to prepare a mixed slurry, which is Component B; Component B is tested and the setting time is measured to be 201 min and the fluidity is 354 mm.

[0079] Verification of the effect of Example 3:

[0080] In this embodiment, component A obtained in step one is filled into a designated area, and another pipeline is laid to simultaneously inject component B obtained in step two into the filling area, thus obtaining a sample filled with coal gangue-based spherical multi-component composite material; then, the sample filled with coal gangue-based spherical multi-component composite material is tested according to the standard method of "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107—2010), and the 1-day compressive strength of the sample is finally determined to be 6.5 MPa.

[0081] Example 4:

[0082] This embodiment provides a coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B. Component A is made from coal gangue, clay, glutinous rice flour, water glass, and water, wherein the mass ratio of coal gangue:clay:glutinous rice flour:water glass:water is 70:20:10:6:30. Component B is made from cementitious materials, gypsum, lime, and water, wherein the cementitious material is silicate cement, and the mass ratio of cementitious material:gypsum:lime:water is 70:20:10:120.

[0083] In this embodiment, the preparation method of the coal gangue-based spherical multi-component composite material for coal mine backfilling specifically includes the following steps:

[0084] Step 1: Preparation of Component A (Component A is prepared according to the process flow of "gangue crushing - screening - batching - additives - pelletizing - solidification - sorting - gradation"):

[0085] Step 1.1, Coal gangue crushing: After the initial screening of the coal gangue raw material at the factory, the large pieces of coal gangue with a particle size ≥ 50mm are crushed by a PEY300×900 hydraulic jaw crusher to obtain crushed coal gangue from the discharge port. The particle size of the crushed coal gangue is ≤ 30mm.

[0086] Steps 1.2 and 1.3 in this embodiment are the same as steps 1.2 and 1.3 in embodiment 1.

[0087] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution, wherein the mass ratio of water glass to water is 1:6, and the spray flow rate is 1.6L / h.

[0088] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as "mother balls," and their size is increased by continuously binding the mixed material as they roll downwards. The pelletizing machine has an inclination angle of 30° and a rotation speed of 12 r / min. The proportion of coal gangue balls produced is 115% of its own particle size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm screens. Pelletizing ends when the amount undersized is ≤10%, and coal gangue pellets are obtained.

[0089] Steps 1.6 and 1.7 in this embodiment are the same as steps 1.6 and 1.7 in embodiment 1.

[0090] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio, with the ratio of groups A, B, C, D, and E being 5:20:50:20:5. The coal gangue pellets after gradation are the A component, and their natural packing void ratio is 19%.

[0091] Step 2, Preparation of Component B: Mix the cementitious material, gypsum, lime and water to obtain a mixed slurry, which is Component B; Test Component B and determine that the setting time of Component B is 190 min and the fluidity is 280 mm.

[0092] Effect verification of Example 4:

[0093] In this embodiment, component A obtained in step one is filled into a designated area, and another pipeline is laid to simultaneously inject component B obtained in step two into the filling area, thus obtaining a sample filled with coal gangue-based spherical multi-component composite material; then, the sample filled with coal gangue-based spherical multi-component composite material is tested according to the standard method of "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107—2010), and the 1-day compressive strength of the sample is finally determined to be 10.4 MPa.

[0094] Comparative Example 1:

[0095] This comparative example provides a coal gangue-based spherical multi-component composite material for coal mine backfilling, which is basically the same as the coal gangue-based spherical multi-component composite material in the examples, except that it lacks the glutinous rice component. Component A in this comparative example is made from coal gangue, clay, water glass, and water.

[0096] This comparative example presents a coal gangue-based spherical multi-component composite material for coal mine backfilling, comprising component A and component B. Component A is made from coal gangue, clay, water glass, and water, wherein the mass ratio of coal gangue:clay:water glass:water is 70:30:5:25. Component B is made from cementitious materials, gypsum, lime, and water, wherein the cementitious material is silicate cement, and the mass ratio of cementitious material:gypsum:lime:water is 70:20:10:130.

[0097] In this comparative example, the preparation method of the coal gangue-based spherical multi-component composite material for coal mine backfilling specifically includes the following steps:

[0098] Step 1: Preparation of Component A (Component A is prepared according to the process flow of "gangue crushing - screening - batching - additives - pelletizing - solidification - sorting - gradation"):

[0099] Step 1.1, Coal gangue crushing: After the initial screening of the coal gangue raw material at the factory, the large pieces of coal gangue with a particle size ≥ 50mm are crushed by a PE150×250 jaw crusher to obtain crushed coal gangue from the discharge port. The particle size of the crushed coal gangue is ≤ 30mm.

[0100] Step 1.2, Ingredient preparation: After preparing the clay according to the mass ratio of coal gangue to clay of 70:30, put it into the pelletizing machine in advance.

[0101] Step 1.3, Screening: After mixing the crushed coal gangue with the uncrushed coal gangue raw material, the mixture is screened into 5 groups according to the particle size range of 0-10mm, 10-20mm, 20-30mm, 30-40mm and 40-50mm through a grading screen. The 5 groups of coal gangue are then fed into a baller containing clay.

[0102] Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution, wherein the mass ratio of water glass to water is 1:5, and the spraying flow rate is 1.4L / h.

[0103] Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing clay. The coal gangue particles themselves act as "mother balls," and the size is increased by continuously binding clay together as they roll downwards. The pelletizing machine has an inclination angle of 35° and a rotation speed of 15 r / min. The proportion of coal gangue balls produced is 107% of its own particle size. The pellets are uniformly collected through 10mm, 20mm, 30mm, 40mm, and 50mm sieves. Pelletizing ends when the amount undersized is ≤10%, and coal gangue pellets are obtained.

[0104] Step 1.6, Curing: Place the 5 groups of coal gangue pellets in an environment of 25±5℃ and 30% relative humidity for natural curing for 3 days. At this time, there is no obvious moisture residue on the surface of the pellets, and the curing is completed.

[0105] Step 1.7, Sorting: The solidified coal gangue pellets are divided into five groups, A, B, C, D, and E, according to the particle size ranges of ≤10mm, 10~25mm, 25~40mm, 40~55mm, and ≥55mm.

[0106] Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio, with the ratio of groups A, B, C, D, and E being 10:20:40:20:10. The coal gangue pellets after gradation are the A component, and their natural packing void ratio is 27%.

[0107] Step 2, Preparation of Component B: The cementitious material, gypsum, lime and water are mixed to obtain a mixed slurry, which is Component B; Component B is tested and the setting time is determined to be 205 min and the fluidity is 321 mm.

[0108] Verification of the effect of Example 1:

[0109] In this comparative example, component A obtained in step one was filled into a designated area, and another pipeline was laid to simultaneously inject component B obtained in step two into the filling area, thus obtaining a sample filled with coal gangue-based spherical multi-component composite material. Then, the sample filled with coal gangue-based spherical multi-component composite material was tested according to the standard method of "Standard for Testing and Evaluation of Concrete Strength" (GB / T 50107—2010), and the 1-day compressive strength of the sample was finally determined to be 2.3 MPa.

Claims

1. A coal gangue-based spherical multi-component composite material for coal mine backfilling, characterized in that, Includes component A and component B; The A component is made from coal gangue, clay, glutinous rice flour, binder and water. The mass ratio of coal gangue, clay, glutinous rice flour, binder and water is (50-80):(10-40):(5-20):(2-8):(20-40). The B component is made from cementitious materials, retarder, lime and water as raw materials, and the mass ratio of cementitious materials, retarder, lime and water is (50-80):(10-40):(2-20):(100-150). The preparation of the coal gangue-based spherical multi-component composite material for coal mine backfilling includes the following steps: Step 1, Prepare component A: Step 1.1, coal gangue crushing; Step 1.2, Ingredient preparation: Mix glutinous rice flour and clay in advance to form a mixture, then put it into the pelletizing machine; Step 1.3, Screening: After mixing the crushed coal gangue with the uncrushed coal gangue raw material, the mixture is screened into five groups according to the particle size range of 0-10 mm, 10-20 mm, 20-30 mm, 30-40 mm and 40-50 mm through a grading screen. The five groups of coal gangue are then fed into a pelletizer containing the mixture. Step 1.4, Additives: During the pelletizing process, liquid is sprayed onto the material through a water sprayer above the pelletizing machine. This liquid is water glass liquid prepared by dilution. Step 1.5, Pelletizing: Coal gangue is continuously sprayed with water glass liquid and rotated in a pelletizing machine containing the mixed material. The coal gangue particles themselves act as the mother balls, and the mixed material is continuously bonded together to increase their size as they roll downwards. The pellets are collected uniformly through 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm screens. Pelletizing ends when the amount of material passing through the screen is ≤10%, and coal gangue pellets are obtained. Step 1.6, Curing; Step 1.7, Sorting: The solidified coal gangue pellets are divided into five groups according to the particle size ranges of ≤10 mm, 10~25 mm, 25~40 mm, 40~55 mm and ≥55 mm. Step 1.8, gradation: Mix the 5 groups of coal gangue pellets according to the continuous gradation ratio. The mass ratio of the first group, the second group, the third group, the fourth group and the fifth group is 10:20:40:20:

10. The coal gangue pellets after gradation are the A component. Step 2, Preparation of Component B: Component B is prepared by mixing cementitious materials, retarder, lime and water.

2. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, The mass ratio of coal gangue, clay, glutinous rice flour, binder and water is (60-70):(15-30):10:5:(25-30); the mass ratio of cementitious material, retarder, lime and water is (65-70):(20-25):(5-15):(120-130).

3. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, The cementing material is selected from one or more of silicate cement and sulfoaluminate cement.

4. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, The retarder mentioned is gypsum.

5. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, Step 1.1 is as follows: After the coal gangue raw material is initially screened at the factory, the large pieces of coal gangue with a particle size ≥ 50 mm are crushed and crushed coal gangue is obtained from the discharge port. The particle size of the crushed coal gangue is ≤ 30 mm.

6. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, In step 1.4, the spray flow rate is 1.5 to 1.6 L / h.

7. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, In step 1.5, the baller is tilted at 35° and rotated at 15 r / min.

8. The coal gangue-based spherical multi-component composite material for coal mine backfilling as described in claim 1, characterized in that, Step 1.6 specifically involves placing five groups of coal gangue pellets in an environment of 25±5℃ and 30% relative humidity for natural curing for 3 days, after which the curing process is complete.

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