Coal-based foaming material for filling gob roadway of coal seam, preparation method and filling method

Abstract

The invention discloses a coal-based foaming material for filling an empty roadway of a coal seam and a preparation and filling method of the coal-based foaming material. According to the method, mined raw coal is crushed by using an underground crushing system, and crushed raw coal particles are mixed and stirred with cement and water and are mixed and stirred with foam formed by air compression of a foaming machine; gypsum and a foam stabilizer are added in the stirring process, the coal-based foaming filling material is obtained after uniform stirring, and finally the coal-based foaming filling material is pumped to a coal seam empty roadway through equipment such as a filling pump and a pipeline for filling operation. The method is easy to operate and practical, the potential safety hazard of the roof caused by traditional methods such as working face inclination adjustment and empty roadway passing is avoided, and meanwhile the problem that coal is difficult to sort after traditional coal seam empty roadway filling is solved.

Description

Technical Field

[0001] This patent relates to the field of coal-based foamed material preparation and filling method, and in particular to a coal-based foamed material for filling coal seam tunnels, its preparation and filling method. Background Technology

[0002] Currently, the main measures taken for working faces to cross empty roadways include: adjusting the working face inclination, strengthening the cut-off support, and using the bottom or top to cross the empty roadway. However, these measures are often complex in operation and difficult to achieve fast, safe, and efficient passage through empty roadways. For example, the method of adjusting the working face inclination combined with strengthening the support requires increasing or decreasing the length of the working face. During the application of the working face, it is easily affected by the coal seam dip angle and mine pressure manifestation, causing the support to tilt, leading to instability of the working face equipment and posing safety problems. Existing methods of filling for crossing empty roadways easily cause the mined raw coal to mix with the filling material (such as gangue), making it difficult to separate. Moreover, the mining equipment and support equipment are easily affected by the performance of the filling material. If the strength of the filling material is too high, the mining equipment will wear down; if the strength of the filling material is too low, it will easily cause roof collapse. Therefore, from the perspectives of safety and economy, in order to achieve safe passage of working faces through empty roadways, it is urgent to find a new filling material, preparation method, and filling method. Summary of the Invention

[0003] To address the aforementioned challenges, this invention provides a coal-based foamed material for filling coal seam voids, its preparation, and a filling method. This method solves problems such as low efficiency in filling voids and susceptibility to coal seam occurrence conditions. Furthermore, it overcomes difficulties such as high filling costs, complex processes, and the difficulty in separating the filling material from the raw coal.

[0004] The first objective of this invention is to provide a coal-based foamed material for filling coal seam voids, wherein the mass percentages of each component in the coal-based foamed material are as follows: raw coal coarse aggregate 30.40%–58.86%, cement 6.54%–30.40%, foaming agent 0.07%–0.3%, gypsum 0.46%–2.13%, foam stabilizer 0.07%–0.3%, with the balance being water, wherein the raw coal coarse aggregate is raw coal with a particle size of less than 0.1 mm.

[0005] Optionally, in some embodiments of the present invention, the foaming agent includes at least one of HTQ-1 composite foaming agent, polymeric composite foaming agent, hydrogen peroxide, etc. The dosage of the foaming agent is based on the mass of cement.

[0006] Optionally, in some embodiments of the present invention, the foam stabilizer includes at least one of calcium stearate, silicone polyether emulsion, etc.

[0007] Optionally, in some embodiments of the present invention, the density of the coal-based foamed material is less than 0.6 × 10⁻⁶. 3 kg·m -3 The expansion ratio is more than 3 times.

[0008] Further optionally, in some embodiments of the present invention, the density of the coal-based foaming material is 0.5 × 10⁻⁶. 3 -0.6×10 3 kg·m -3 The expansion ratio is 3-3.5 times.

[0009] Optionally, in some embodiments of the present invention, the compressive strength of the coal-based foamed material is not less than 1 MPa.

[0010] Further optionally, in some embodiments of the present invention, the compressive strength of the coal-based foamed material is not less than 1.5 MPa.

[0011] Furthermore, optionally, in some embodiments of the present invention, the compressive strength of the coal-based foamed material is 1.5 MPa to 3.0 MPa.

[0012] A second objective of this invention is to provide a method for preparing a coal-based foamed material for filling coal seam voids, as described above, comprising the following steps:

[0013] ① The mined raw coal is crushed to a particle size of less than 0.1 mm and used as raw coal coarse aggregate;

[0014] ② The raw coal coarse aggregate is mixed with cement and water in a mass ratio of 5-9:1-5:5 to prepare a preliminary slurry;

[0015] ③ Dilute the foaming agent with water at a mass ratio of 1:20 to prepare a diluted solution, add a foam stabilizer, and then compress the solution with air using a foaming machine to produce foam;

[0016] ④ Mix the initial slurry with foam, add additives, and stir to prepare a coal-based foaming material. The additives are gypsum.

[0017] Optionally, in some embodiments of the present invention, the slurry concentration of the coal-based foaming material is 63.53% to 66.00% by weight.

[0018] Optionally, in some embodiments of the present invention, in step ③, the conditions for foaming by air compression in the foaming machine include a required compressed air pressure of 0.5–0.8 MPa, dry air, and a temperature that is not too high.

[0019] Optionally, in some embodiments of the present invention, in step ④, the stirring conditions include a stirring speed of 1000-1500 r / min and a stirring time of about 5 min; more preferably, the stirring time is 3-10 min.

[0020] A third objective of this invention is to provide a coal seam cavity filling system that uses a coal-based foamed material for coal seam cavity filling as described above.

[0021] Beneficial effects:

[0022] Compared with existing working face through-hole technology, it has the following advantages:

[0023] 1) This invention uses raw coal as the aggregate for filling and foamed slurry as an auxiliary material. The resulting coal-based foamed filling material not only avoids the safety hazards such as roof collapse caused by deformation and damage of the coal seam when adjusting the angle of the working face through the coal seam, but also solves the problem of difficulty in sorting caused by the mixing of gangue filling material and raw coal in the traditional coal seam, thus realizing continuous, efficient and safe mining.

[0024] 2) The coal-based foamed filling material prepared by this method uses simple and convenient equipment, is easy to operate, and is lightweight with high strength. Its density and strength are adjustable (28-day density is less than 0.6 × 10⁻⁶). 3 kg·m -3 The expansion ratio is generally above 3 times; the strength range is generally 1.0 to 3 MPa. After foaming, the slurry has good flow properties, making it particularly suitable for filling coal seam tunnels. It allows more tunnels to be filled with less material, reducing the loss of filling materials and achieving green mining. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the principle of a method for preparing coal-based foamed materials for filling coal seam voids.

[0026] Figure 2 This is a schematic diagram illustrating the principle of a method for preparing coal-based foamed materials for filling coal seam voids.

[0027] Figure 3 This is a schematic diagram of a coal-based foamed material filling method for filling coal seam voids. (a) Plan view of coal seam void filling, (b) Cross-sectional view of AA-filled void.

[0028] In the diagram, the components are: 1. Raw coal conveyor belt; 2. Crusher; 3. Batching machine; 4. Water storage tank; 5. Foaming machine; 6. Mixer; 7. High-pressure pump; 8. Coal-based foaming material; 9. Filling pipeline; 10. Retaining wall; and 11. Coal seam tunnel. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the present invention as described in detail in the claims.

[0030] Example

[0031] This invention proposes a coal-based foamed material for filling coal seam tunnels, its preparation and filling method. By analyzing the destructive influence of coal seam mining on tunnels, a suitable material ratio is selected to prepare the coal-based foamed material, and the prepared coal-based filling material is pumped to the coal seam tunnel through pipeline.

[0032] like Figure 1 As shown, this invention discloses a method for preparing coal-based foamed material for filling coal seam tunnels and a filling process. The material preparation requires equipment such as a raw coal conveyor belt 1, a crusher 2, a batching machine 3, a water storage tank 4, a foaming machine 5, a mixer 6, a high-pressure pump 7, and a filling pipeline 9. Figure 2 , Figure 3 As shown, the specific steps are as follows;

[0033] (1) The raw coal transported by the raw coal conveyor belt 1 is crushed by the crusher 2 to obtain raw coal particles with a particle size of less than 0.1 mm, which are used as raw coal coarse aggregate;

[0034] (2) The batching machine 3 then mixes the raw coal coarse aggregate and cement with the water in the water storage tank 4 using the mixer 6 according to a reasonable ratio to obtain the initial slurry.

[0035] (3) At the same time, the foaming agent is mixed and diluted with water, and a foam stabilizer is added to obtain a reasonably diluted foaming agent solution. The solution is then compressed by the air in the foaming machine 5 under a compressed air pressure of 0.5 to 0.8 MPa to obtain foam.

[0036] (4) The initial slurry obtained is mixed with the foam obtained, and a certain amount of admixtures (additives include gypsum, etc.) are added. The mixture is stirred in a mixer 6 at a stirring speed of 1000-1500 r / min for about 5 minutes to obtain a coal-based foaming material 8 with a slurry concentration of 63.53%-66.00%.

[0037] (5) Construct a retaining wall 10 at the end of the coal seam tunnel to make the tunnel a closed space and prevent the slurry from being lost;

[0038] (6) The prepared coal-based foamed filling material is pumped to the coal seam tunnel 11 using the high-pressure pump 8 and the filling pipeline 9. The coal seam tunnel is filled in stages. When the grout reaches the roof, the grouting is stopped.

[0039] In some examples, the slurry concentration of the coal-based foaming material is generally 63.53% to 66.00%.

[0040] In some examples, the raw coal is raw coal particles with a particle size of <0.1 mm obtained after crushing.

[0041] In some examples, the mass percentages of each component in the coal-based foamed material are as follows, by weight: raw coal coarse aggregate 30.40%–58.86%, cement 6.54%–30.40%, foaming agent 0.07%–0.3%, gypsum 0.46%–2.13%, foam stabilizer 0.07%–0.3%, with the balance being water.

[0042] In some examples, by analyzing the destructive impact of coal seam mining on the tunnel, and then adjusting the expansion ratio of the filling material, the particle size and dosage of raw coal, the water-ash ratio, the dosage of additives, and other proportioning parameters, coal-based foamed materials that meet the strength requirements of tunnels in different coal seams can be obtained.

[0043] This invention uses raw coal as the aggregate for the filling material and foamed slurry as an auxiliary material to produce coal-based foamed filling material. The prepared coal-based foamed filling material requires simple and convenient equipment, is easy to operate, and is lightweight, high-strength, with adjustable density and strength; the slurry has good flow properties after foaming. From an economic perspective, it not only solves the problem of difficult raw coal sorting caused by traditional coal seam goaf filling with gangue, improving work efficiency, but also reduces the loss of filling material due to its high expansibility. From a safety perspective, it avoids the problems of difficult surrounding rock control, strong mine pressure manifestation, and roof safety hazards caused by traditional working face adjustment through coal seam goaf, achieving continuous, efficient, and safe mining.

[0044] Example 1

[0045] Coal-based foaming material ingredients: by mass percentage, raw coal 37.13%, cement 24.75%, foaming agent 0.25%, gypsum 1.73%, foam stabilizer 0.25%, with the balance being water. The total mass percentage of the above substances is 100%, which prepares a coal-based foaming material with a slurry concentration of 64.11%.

[0046] The method for preparing coal-based foamed material for filling coal seam voids in this embodiment includes the following steps:

[0047] ① The mined raw coal is crushed to a particle size of less than 0.1 mm and used as raw coal coarse aggregate;

[0048] ② The raw coal coarse aggregate is mixed with cement and water in a mass ratio of 6:4:5 (the amount of water added here is 30.94wt%) to prepare a preliminary slurry;

[0049] ③ The foaming agent is mixed and diluted with water at a mass ratio of 1:20 (the amount of water added here is 4.95wt%) to prepare a diluted solution, and a foam stabilizer is added. Then, the solution is produced by air compression in a foaming machine 5 under a compressed air pressure of 0.8MPa.

[0050] ④ Mix the initial slurry with foam, add additives, and stir in mixer 6 at a stirring speed of 1200 r / min for 5 min to prepare coal-based foaming material. The additives are 1.73% gypsum and 0.25% foam stabilizer.

[0051] Example 2

[0052] The operation was carried out according to the method of Example 1, except that the coal-based foaming material was prepared by mass percentage as follows: raw coal 30.40%, cement 30.40%, foaming agent 0.30%, gypsum 2.13%, foam stabilizer 0.30%, with the remainder being water. The total mass percentage of the above substances was 100%, and a coal-based foaming material with a slurry concentration of 63.53% was prepared.

[0053] The method for preparing coal-based foamed material for filling coal seam voids in this embodiment includes the following steps:

[0054] ① The mined raw coal is crushed to a particle size of less than 0.1 mm and used as raw coal coarse aggregate;

[0055] ② The raw coal coarse aggregate is mixed with cement and water in a mass ratio of 5:5:5 (the amount of water added here is 30.40 wt%) to prepare a preliminary slurry;

[0056] ③ The foaming agent is mixed and diluted with water at a mass ratio of 1:20 (the amount of water added here is 6.07wt%) to prepare a diluted solution, and a foam stabilizer is added. Then, the solution is produced by air compression in a foaming machine 5 under a compressed air pressure of 0.8MPa.

[0057] ④ Mix the initial slurry with foam, add additives, and stir in mixer 6 at a stirring speed of 1000 r / min for 5 min to prepare coal-based foaming material. The additives are 2.13% gypsum and 0.30% foam stabilizer.

[0058] Example 3

[0059] The operation was carried out according to the method of Example 1, except that the coal-based foaming material was prepared by mass percentage as follows: 44.11% raw coal, 18.90% cement, 0.19% foaming agent, 1.32% gypsum, 0.19% foam stabilizer, and the balance being water. The total mass percentage of the above substances was 100%, and a coal-based foaming material with a slurry concentration of 64.71% was prepared.

[0060] The method for preparing coal-based foamed material for filling coal seam voids in this embodiment includes the following steps:

[0061] ① The mined raw coal is crushed to a particle size of less than 0.1 mm and used as raw coal coarse aggregate;

[0062] ② The raw coal coarse aggregate is mixed with cement and water in a mass ratio of 7:3:5 (the amount of water added here is 31.51 wt%) to prepare a preliminary slurry;

[0063] ③ The foaming agent is mixed with water at a mass ratio of 1:20 (the amount of water added here is 3.78wt%) to prepare a diluted solution, and a foam stabilizer is added. Then, the solution is produced by air compression in a foaming machine 5 under a compressed air pressure of 0.8MPa.

[0064] ④ Mix the initial slurry with foam, add additives, and stir in mixer 6 at a stirring speed of 1200 r / min for 5 min to prepare coal-based foaming material. The additives are 1.32% gypsum and 0.19% foam stabilizer.

[0065] Example 4

[0066] The procedure was followed according to Example 1, except that the coal-based foaming material was prepared as follows: by mass percentage, raw coal 58.86%, cement 6.54%, foaming agent 0.07%, gypsum 0.46%, foam stabilizer 0.07%, with the remainder being water. The total mass percentage of all the above substances was 100%, resulting in a coal-based foaming material with a slurry concentration of 66.00%.

[0067] The method for preparing coal-based foamed material for filling coal seam voids in this embodiment includes the following steps:

[0068] ① The mined raw coal is crushed to a particle size of less than 0.1 mm and used as raw coal coarse aggregate;

[0069] ② The raw coal coarse aggregate is mixed with cement and water in a mass ratio of 9:1:5 (the amount of water added here is 32.70 wt%) to prepare a preliminary slurry;

[0070] ③ The foaming agent is mixed with water at a mass ratio of 1:20 (the amount of water added here is 1.30wt%) to prepare a diluted solution, and a foam stabilizer is added. Then, the solution is produced by air compression in a foaming machine 5 under a compressed air pressure of 0.5MPa.

[0071] ④ Mix the initial slurry with foam and add additives. Stir the mixture in mixer 6 at a stirring speed of 1500 r / min for 5 min to prepare a coal-based foaming material. The additives are 0.46% gypsum and 0.07% foam stabilizer.

[0072] Test Case

[0073] (1) Conveying performance slump

[0074] The slump test of conveying performance in the laboratory mainly includes steps such as mixing materials, filling molds, vibration, demolding, and curing. According to the GB / T 50080 test standard, a slump cone with a height of 300 mm, a top diameter of 100 mm, and a bottom diameter of 200 mm was used in the test to test the slump of the slurry of the materials under different coal-based foaming material ratio design schemes in Examples 1 to 4 above.

[0075] The experimental test results showed that the slump was 255mm, 248mm, 257mm and 262mm respectively, which met the basic requirements for pipeline transportation.

[0076] (2) Density test

[0077] During the density test, an LP3102 electronic balance (maximum weighing capacity 3100g, sensitivity 0.01g) and vernier calipers were used to measure the mass and volume of the specimens, thus obtaining the original density of the coal-based foamed filling material. The experimental results showed that, with a curing period of 28 days, the average densities of the products in Examples 1-4 were 0.5795 × 10⁻⁶. 3 kg·m -3 0.5962×10 3 kg·m -3 0.5678×10 3 kg·m -3 0.5496×10 3 kg·m -3 The density of cement slurry without foaming treatment is 1.8200 × 10⁻⁶. 3 kg·m -3 In comparison, the volume expansion ratio of coal-based foamed filling materials is more than 3 times, which greatly reduces the consumption of filling materials.

[0078] (3) Mechanical property testing

[0079] During the mechanical property testing process, a sample with dimensions of 70.7×70.7×70.7mm was used. 3 Standard cubic specimens of cementitious filling material were prepared. After the specimens were placed in a mold, the open mold was placed under standard conditions of 23±2℃ and 95% relative humidity for curing. After initial setting, the specimens were removed from the mold and cured under standard conditions for another 28 days.

[0080] The compressive strength test results of the coal slurry water-cemented backfill materials prepared in Examples 1-4 were 2.2 MPa, 3 MPa, 1.9 MPa, and 1.5 MPa, respectively, which meet the strength requirements for backfilling coal seams. Based on the above test results and actual engineering requirements, a suitable mix ratio was selected for field application.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A coal-based foaming material for filling coal seam empty tunnels, characterized in that: Calculated by weight percentage, the mass percentage of each component in the coal-based foaming material is: 30.40% to 58.86% of raw coal coarse aggregate, 6.54% to 30.40% of cement, 0.07% to 0.3% of foaming agent, 0.46% to 2.13% of gypsum, 0.07% to 0.3% of foam stabilizer, and the balance is water. The raw coal coarse aggregate is raw coal with a particle size of less than 0.1 mm.

2. The coal-based foaming material for filling coal seam empty tunnels according to claim 1, characterized in that: The foaming agent includes at least one of HTQ-1 composite foaming agent, polymer composite foaming agent and hydrogen peroxide.

3. The coal-based foaming material for filling coal seam empty tunnels according to claim 1, characterized in that: The foam stabilizer includes at least one of calcium stearate and silicone polyether emulsion.

4. The coal-based foaming material for filling coal seam empty tunnels according to claim 1, characterized in that: The density of coal-based foaming material is less than 0.6×10 3 kg·m -3 , the expansion ratio is more than 3 times; and / or Preferably, the density of the coal-based foaming material is 0.5×10 3 -0.6×10 3 kg·m -3 , the expansion ratio is 3-3.5 times; and / or Preferably, the compressive strength of the coal-based foaming material is not less than 1 MPa; and / or Preferably, the compressive strength of the coal-based foaming material is not less than 1.5 MPa; and / or Preferably, the compressive strength of the coal-based foamed material is 1.5 MPa to 3.0 MPa.

5. The method for preparing a coal-based foamed material for filling coal seam empty tunnels according to any one of claims 1 to 4, characterized in that: The following steps are involved: ① Crushing the mined raw coal to a particle size of less than 0.1 mm as raw coal coarse aggregate; ② Mix the raw coal coarse aggregate with cement and water in a mass ratio of 5-9:1-5:5 to prepare a preliminary slurry; ③ Dilute the foaming agent and water in a mass ratio of 1:20 to make a diluent, add a foam stabilizer, and then compress the air through a foaming machine to make foam; ④ Mixing the preliminary slurry with the foam, adding an additive, and stirring to prepare a coal-based foaming material, wherein the additive is gypsum.

6. The method according to claim 5, characterized in that The slurry concentration of the coal-based foaming material is 63.53% to 66.00% by mass.

7. The method according to claim 5, characterized in that In step ③, the conditions for the foaming machine to compress the air for foaming include that the required compressed air pressure is 0.5-0.8MPa.

8. The method according to claim 5, characterized in that In step ④, the stirring conditions include a stirring speed of 1000-1500 r / min and a stirring time of 3-10 min.

9. A coal seam empty road filling system, characterized in that: A coal-based foaming material for filling coal seam empty tunnels as described in any one of claims 1 to 4.

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