Safe and environment-friendly coal-based waste modified hole sealing material and preparation method thereof

Abstract

The invention provides a safe and environment-friendly coal-based waste modified hole sealing material, the modified hole sealing material comprises a dry material mixture and water, the dry material mixture comprises the following components by weight: 68-88 parts of coal-based waste; 3 to 5 parts of hydrogel; 2 parts of a bionic binder; 1-5 parts of a modifier; the coal-based wastes comprise coal gangue powder, pulverized coal and fly ash in a weight part ratio of (5-6): 1: 4; the hydrogel is prepared from cellulose ether, high-molecular water-absorbent resin, glyoxal and sodium polyhydroxycarboxylate; the bionic adhesive is prepared from at least one of 3, 4-dihydroxy phenylalanine, N-(N-L-gamma-glutamyl-L-cysteinyl) glycine, acrylic acid and ammonium persulfate. The modified hole sealing material has the advantages of environmental protection, low cost, efficient hole sealing and the like. The invention also discloses a preparation method of the material. The preparation method is simple and feasible.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal mine gas extraction, and in particular relates to a safe and environmentally friendly coal-based waste modified sealing material and a preparation method thereof. Background Art

[0002] In the field of coal mine gas extraction technology, the selection and application of sealing materials are directly related to the effect of gas extraction and the safe production of coal mines. Traditional sealing materials are mainly divided into two categories: inorganic materials and organic materials. However, these two types of materials have many shortcomings in practical applications.

[0003] Inorganic materials usually have high strength and stability, but their interface interaction with coal seams is poor, making it difficult to tightly bond with coal seams, resulting in poor sealing effects. At the same time, the preparation and application of inorganic materials are often accompanied by high energy consumption and high pollution, which is contrary to the current environmental protection concept.

[0004] Organic materials usually have good flexibility and sealing properties, but their performance is often not stable enough and is easily affected by the complex underground environment. In addition, the high cost of organic materials also limits their widespread application in coal mine gas extraction.

[0005] More importantly, existing sealing materials often fail to meet the requirements of safety, environmental protection and high efficiency at the same time. Many sealing materials produce harmful substances during use, polluting the coal mine environment and even posing a threat to the health of miners. At the same time, the preparation process of some sealing materials is complicated and costly, which is not conducive to the sustainable development of coal mining enterprises.

[0006] In view of the above problems, it is particularly important to develop an efficient, environmentally friendly and cost-effective sealing material. Summary of the invention

[0007] The present invention aims at the above problems, makes up for the deficiencies of the prior art, and provides a safe and environmentally friendly coal-based waste modified sealing material. The modified sealing material comprises a dry material mixture and water, wherein the weight ratio of the dry material mixture to water is 1.8-2:1, wherein the dry material mixture has the following components in parts by weight:

[0008] 68-88 parts of coal-based waste;

[0009] 3-5 parts of hydrogel;

[0010] 2 parts of biomimetic adhesive;

[0011] 1-5 parts of modifier;

[0012] The coal-based waste is coal gangue powder, coal powder, and fly ash, and the weight ratio of coal gangue powder, coal powder, and fly ash is 5-6:1:4;

[0013] The hydrogel contains cellulose ether, superabsorbent polymer, glyoxal, and polyhydroxycarboxylate sodium;

[0014] The binder contains at least one of 3,4-dihydroxyphenylalanine, N-(N-L-γ-glutamyl-L-cysteinyl)glycine, acrylic acid, and ammonium persulfate;

[0015] The modifier contains a retarder, an expansive agent, an early strength agent, an alkaline activator, and a surfactant.

[0016] Preferably, the weight ratio of the retarder, the expansive agent, the early strength agent, the alkaline activator, and the surfactant is 1:1:1:1:1.

[0017] Preferably, the retarder is at least one of polyacrylamide and sodium gluconate.

[0018] Preferably, the expansive agent includes aluminum powder and calcium oxide, and the weight ratio of the aluminum powder to the calcium oxide is 1:1.

[0019] Preferably, the early strength agent is carbon nanotubes, the specific surface area of the carbon nanotubes is 380 m 2 / g, the bulk density of the carbon nanotubes is 50 g / L, and the average primary particle size of the carbon nanotubes is 7 nm.

[0020] Preferably, the alkaline activator is sodium silicate.

[0021] Preferably, the surfactant is at least one of sodium dodecyl sulfate, quaternary ammonium salt, lauric acid, and cardanol.

[0022] Another object of the present invention is to provide a preparation method of the safe and environmentally friendly coal-based waste modified sealing material as described above, including the following steps:

[0023] ① Grind the coal-based waste into powder by a ball mill or a jet mill system;

[0024] ② Mix the ground coal-based waste with the hydrogel, the bionic binder, and the modifier, and stir with a high-speed mixer at a speed of 300-500 rpm for 1-2 min to form a dry material mixture;

[0025] ③ Add water and stir at a speed of 500-800 rpm for 3-5 min to form a gel-type composite slurry, i.e., the modified sealing material.

[0026] The mechanism of the present invention:

[0027] The present invention uses coal-based waste as the main base material, improves the adhesiveness and stability of the modified hole-sealing material through a bionic binder, improves the water absorption and water retention of the modified hole-sealing material through a hydrogel, and adjusts the properties of the modified hole-sealing material through modifiers such as a retarder, an expander, and an early strength agent, thereby improving the hole-sealing effect.

[0028] Advantages of the present invention:

[0029] 1. Resource recycling and environmental protection improvement: The present invention uses coal-based waste as the main base material, which not only effectively reduces the accumulation of mine waste but also significantly reduces the environmental pollution caused by coal-based waste.

[0030] 2. Reduction of material cost: By using coal-based waste as the main base material, the procurement and transportation costs of external raw materials are avoided, the production cost of the modified hole-sealing material is reduced, and its market competitiveness is enhanced.

[0031] 3. Significantly improved hole-sealing effect: By optimizing the raw material ratio and preparation process, the prepared modified hole-sealing material exhibits excellent anti-dry shrinkage and compressive strength. Its excellent anti-dry shrinkage can effectively prevent the leakage of coal seam gas and ensure the long-term stability of hole sealing. At the same time, the bonding force with the coal wall is greatly improved, and the bonding strength is significantly increased, ensuring that the modified hole-sealing material can still maintain a good sealing effect under high-pressure conditions.

[0032] 4. Adapt to complex underground conditions: Aiming at the problem that traditional modified hole-sealing materials are difficult to adapt to the increasingly complex underground conditions, the prepared modified hole-sealing material of the present invention can maintain a stable hole-sealing effect in various complex environments due to its excellent performance stability and adaptability, providing a strong guarantee for the safe production of coal mines. Description of the drawings

[0033] Figure 1 is the particle size distribution diagram of fly ash and coal gangue powder used in Example 1.

[0034] Figure 2 is the comparison diagram of the dry shrinkage rate of the modified hole-sealing material prepared in Example 1 and the control example.

[0035] Figure 3 is the comparison diagram of the compressive strength test of the modified hole-sealing material prepared in Example 1 and the control example. Detailed implementation manners

[0036] In order to make the technical problems, technical solutions, and beneficial effects solved by the present invention clearer and more understandable, the following further details the present invention in combination with specific implementation manners. It should be understood that the specific implementation manners described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Example 1

[0038] Prepare a safe and environmentally friendly coal-based waste modified sealing material according to the following method:

[0039] ① Grind the coal-based waste to a particle size of 0.125 mm through a ball milling device; the coal-based waste includes coal gangue powder, coal powder, and fly ash, and the weight ratio of coal gangue powder, coal powder, and fly ash is 5:1:4, that is, the mass of fly ash accounts for 50% of the mass of the coal-based waste, the mass of coal powder accounts for 10% of the mass of the coal-based waste, and the mass of coal gangue powder accounts for 40% of the mass of the coal-based waste;

[0040] ② Mix the ground coal-based waste, hydrogel, bionic binder, and modifier according to a weight ratio of 68:5:2:5, and use a high-speed mixer to stir at a speed of 300 rpm for 2 min to form a dry material mixture; the hydrogel contains cellulose ether (specifically hydroxyethyl cellulose), superabsorbent resin, glyoxal, and polyhydroxycarboxylate sodium with a weight ratio of 50:40:2:8; the bionic binder uses 3,4-dihydroxyphenylalanine, N-(N-L-γ-glutamyl-L-cysteinyl)glycine, acrylic acid, and ammonium persulfate with a weight ratio of 1:1:4:4; N-(N-L-γ-glutamyl-L-cysteinyl)glycine is also called reduced glutathione, and its molecular formula is C 10 H 17 N3O6S, with a molecular weight of 307.33;

[0041] ③ Add water to the dry material mixture at a weight ratio of 2:1, and stir at a speed of 800 rpm for 5 min to form a gel-type composite slurry, that is, the modified sealing material.

[0042] Among them: the modifier includes a retarder, an expander, an early strength agent, an alkaline activator, and a surfactant with a weight ratio of 1:1:1:1:1;

[0043] The retarder is polyacrylamide and sodium gluconate with a weight ratio of 1:1; the retarder can play a role in delaying the hydration of the coal-based waste, ensuring that the sealing material maintains a certain construction fluidity within a certain period of time and has enough time for subsequent operations;

[0044] The expander is aluminum powder and calcium oxide with a weight ratio of 1:1. The expander makes the sealing material have a certain expansibility. After expansion, it fills the coal seam fissures and improves the sealing effect;

[0045] The early strength agent is carbon nanotubes. The specific surface area of the carbon nanotubes is 380 m 2 / g, the bulk density of the carbon nanotubes is 50 g / L, and the average primary particle size of the carbon nanotubes is 7 nm;

[0046] The alkaline activator is sodium silicate, and the modulus of sodium silicate is 2.2;

[0047] The surfactant is sodium dodecyl sulfate. The surfactant improves the interfacial activity of inorganic and organic materials and enhances the reaction activity of the materials.

[0048] Figure 1 It is the particle size distribution diagram of the fly ash and coal gangue powder used in Example 1, Figure 1 The unit of the abscissa in it is mesh number.

[0049] Example 2

[0050] A safe and environmentally friendly coal-based waste modified sealing material is prepared according to the following method:

[0051] ① Grind the coal-based waste to a particle size of 0.180 mm through an air-flow crushing system; the coal-based waste includes coal gangue powder, coal powder, and fly ash, and the weight ratio of coal gangue powder, coal powder, and fly ash is 6:1:4;

[0052] ② Mix according to the weight ratio of the ground coal-based waste, hydrogel, bionic binder, and modifier of 88:3:2:1, and use a high-speed mixer to stir at a speed of 300 rpm for 1 min to form a dry material mixture; the hydrogel contains cellulose ether (specifically hydroxyethyl cellulose), superabsorbent resin, glyoxal, and polyhydroxycarboxylate sodium with a weight ratio of 50:40:2:8; the bionic binder uses 3,4-dihydroxy-L-phenylalanine, N-(N-L-γ-glutamyl-L-cysteinyl)glycine, acrylic acid, and ammonium persulfate with a weight ratio of 1:1:4:4;

[0053] ③ Add water according to the weight ratio of the dry material mixture to water of 1.8:1, and stir at a speed of 800 rpm for 5 min to form a gel-type composite slurry.

[0054] Among them: the modifier includes a retarder, an expansive agent, an early strength agent, an alkaline activator, and a surfactant with a weight ratio of 1:1:1:1:1;

[0055] The retarder is polyacrylamide; the expansive agent is aluminum powder and calcium oxide with a weight ratio of 1:1; the early strength agent is carbon nanotubes, the specific surface area of the carbon nanotubes is 380 m 2 / g, the bulk density of the carbon nanotubes is 50 g / L, and the average primary particle size of the carbon nanotubes is 7 nm; the alkaline activator is sodium silicate, and the modulus of sodium silicate is 2.2; the surfactants are sodium dodecyl sulfate, quaternary ammonium salt, lauric acid, and cardanol.

[0056] Among them, the fly ash used in Example 2 is Class F first-class fly ash, with a specific surface area of 430 m 2 / kg and a density of 2.42 g / cm3 。

[0057] Construction method: Use a special slurry transfer pump (such as a plunger pump or a screw pump) to transfer the modified hole-sealing material to the construction area through a pipeline to ensure the stable supply of the modified hole-sealing material and avoid settlement or stratification. Insert a hole-sealing pipe into the gas drainage borehole and grout by means of low-pressure grouting (0.2 - 0.5 MPa) to ensure that the modified hole-sealing material fully fills the pores and tightly binds to the hole wall.

[0058] Comparative example

[0059] Comparison of dry shrinkage

[0060] Set traditional cement hole-sealing material and mineral admixture hole-sealing material as comparative examples. Make modules of 70×70×70 mm with the above hole-sealing materials according to the corresponding water-cement ratio, take them out after curing in a constant-temperature drying oven for 28 days, and use a vernier caliper to measure the shrinkage length of the mold cross-section to calculate the dry shrinkage rate. The water-cement ratio is the mass ratio of water to dry material mixture.

[0061] Dry shrinkage rate = [(length of the original cross-section - length of the cross-section after shrinkage) / length of the original cross-section] * 100%

[0062] From Figure 2 ( Figure 2 (the unit of the vertical coordinate is %) it can be seen that the dry shrinkage rate of the modified hole-sealing material of the present invention is significantly better than that of other hole-sealing materials.

[0063] Comparison of compressive strength

[0064] Set blank cement as the test control group. Make modules of 70×70×70 mm with the test materials according to the corresponding water-cement ratio, take them out after curing in a constant-temperature drying oven for 28 days, use an electronic universal testing machine to test the compressive failure load of each group of specimens, the loading speed is 2 mm / min, each group of specimens is tested 3 times, and the average value is taken.

[0065] From Figure 3 ( Figure 3 (the unit of the vertical coordinate is MPa) it can be obtained that under the same water-cement ratio, the compressive strength of the modified hole-sealing material of the present invention is much higher than that of the blank cement hole-sealing material. The compressive strengths of the modified hole-sealing material of the present invention at 1 d, 3 d and 7 d reach 34.39 MPa, 45.91 MPa and 47.54 MPa respectively, which are 1.9, 2.8 and 1.5 times that of the blank cement hole-sealing material under the same water-cement ratio and the same curing time, indicating that the modified hole-sealing material of the present invention has good compressive performance.

[0066] It can be understood that the above specific description of the present invention is only for the purpose of illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those of ordinary skill in the art should understand that the present invention can still be modified or equivalently replaced to achieve the same technical effects; as long as the usage requirements are met, they are all within the protection scope of the present invention.

Claims

1. A safe and environmentally friendly coal-based waste modified hole-sealing material, characterized in that: The modified hole-sealing material includes a dry material mixture and water, and the weight ratio of the dry material mixture to water is 1.8 - 2:

1. The dry material mixture consists of the following components by weight: 68 - 88 parts of coal-based waste; 3 - 5 parts of hydrogel; 2 parts of bionic binder; 1 - 5 parts of modifier; The coal-based waste is coal gangue powder, coal powder, and fly ash, and the weight ratio of coal gangue powder, coal powder, and fly ash is 5 - 6:1:4; The hydrogel contains cellulose ether, superabsorbent polymer, glyoxal, and polyhydroxycarboxylate sodium; The bionic binder contains at least one of 3,4-dihydroxyphenylalanine, N-(N-L-γ-glutamyl-L-cysteinyl)glycine, acrylic acid, and ammonium persulfate; The modifier contains a retarder, an expansive agent, an early strength agent, an alkaline activator, and a surfactant.

2. The safety and environmental protection type coal-based waste modified hole-sealing material according to claim 1, wherein: The weight ratio of the retarder, expansive agent, early strength agent, alkaline activator, and surfactant is 1:1:1:1:

1.

3. The safety and environmental protection type coal-based waste modified hole-sealing material according to claim 1, wherein: The retarder is at least one of polyacrylamide and sodium gluconate.

4. A safe and environmentally friendly coal-based waste modified hole-sealing material according to claim 1, characterized in that: The expansive agent includes aluminum powder and calcium oxide, and the weight ratio of aluminum powder to calcium oxide is 1:

1.

5. The safety and environmental protection type coal-based waste modified hole-sealing material according to claim 1, characterized in that: The early strength agent is carbon nanotubes, and the specific surface area of the carbon nanotubes is 380 m 2 / g, the bulk density is 50 g / L, and the average primary particle size is 7 nm.

6. The safety and environmental protection type coal-based waste modified hole-sealing material according to claim 1, characterized in that: The alkaline activator is sodium silicate.

7. A safe and environmentally friendly coal-based waste modified hole-sealing material according to claim 1, characterized in that: The surfactant is at least one of sodium dodecyl sulfate, quaternary ammonium salt, lauric acid, and cardanol.

8. A preparation method of the safe and environment-friendly coal-based waste modified hole-sealing material according to any one of claims 1 to 7, characterized in that: It includes the following steps: ① Grind the coal-based waste into powder by a ball milling or air jet milling system; ② Mix the ground coal-based waste with hydrogel, bionic binder, and modifier, and stir at a speed of 300 - 500 rpm for 1 - 2 min using a high-speed mixer to form a dry material mixture; ③ Add water and stir at a speed of 500 - 800 rpm for 3 - 5 min to form a gel-type composite slurry, i.e., the modified hole-sealing material.

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