Water retention type rapid gel hole sealing material and preparation method thereof

Abstract

The invention discloses a water retention type rapid gel hole sealing material and a preparation method thereof, and relates to the field of coal mine underground gas extraction hole sealing materials, the water retention type rapid gel hole sealing material comprises 40-80 parts by mass of acrylamide, 0.07-0.14 part by mass of a cross-linking agent, 75-150 parts by mass of fly ash, 10-15 parts by mass of an alkali accelerator, 10-15 parts by mass of a thermal initiator, 10-15 parts by mass of a water retention agent and 10-15 parts by mass of water. The water-retaining agent is prepared from the following components in parts by weight: 24 parts of alkali accelerator, 0.93-1.86 parts of thermal initiator, 17-68 parts of water-retaining agent and 300 parts of water. The prepared hole sealing material can be quickly gelatinized in a short time, has certain obdurability after being gelatinized, and can be deformed along with the action of coal seam stress; the problem that the sealing effect of a common flexible hole sealing material is greatly reduced due to water loss shrinkage and flexibility loss in long-term hole sealing is effectively solved, and application of the flexible material in gas extraction hole sealing is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of sealing materials for underground gas drainage in coal mines, and particularly to a water-retaining rapid gel sealing material and its preparation method. Background Technology

[0002] Gas drainage is the primary technical means of gas control in coal mines, and the quality of borehole sealing directly determines the effectiveness of gas drainage. Traditional sealing materials mainly include cement-based materials and polyurethane, but these materials have significant limitations. Cement-based materials not only have long setting times but are also prone to brittleness after solidification, resulting in poor adhesion to the borehole wall. Polyurethane materials have high viscosity, making them difficult to grout, and are flammable and have poor safety; they also experience cooling and shrinkage after foaming, which leads to a decrease in sealing effectiveness. When drainage is carried out after sealing, the high ground stress in deep mines causes dynamic fractures in the coal seam around the borehole, and traditional rigid sealing materials cannot adapt to this deformation, leading to seal failure.

[0003] Flexible sealing materials can deform in tandem with the coal seam due to their inherent flexibility, thereby improving the sealing effect. However, under conditions of long sealing cycles, the moisture in the flexible sealing material will evaporate and shrink and crack. Once it loses water, its flexibility will be lost. In addition, the stress field of underground coal mining is constantly changing, and the fracture network around the borehole will develop and evolve accordingly. The flexible sealing material that has lost water is easily damaged by the deformation of the coal seam, and the sealing effect will deteriorate sharply.

[0004] To address these issues, there is an urgent need for a water-retaining, rapid-gel sealing material and its preparation method. Summary of the Invention

[0005] To address the aforementioned issues, this application proposes a water-retaining rapid gel sealing material and its preparation method. This sealing material can gel in a short time, and before grouting, it is a low-viscosity, flowable liquid. Under negative pressure, it can seal most coal seam fractures. After gel formation, it also possesses certain toughness and strength, effectively improving sealing performance and extraction efficiency. Furthermore, the addition of a water-retaining agent significantly improves the water retention performance of the flexible sealing material, ensuring that the extraction efficiency will not be greatly reduced due to water loss and shrinkage during long-term sealing operations.

[0006] Specifically, a water-retaining, rapid-gel sealing material comprises the following components: Acrylamide, crosslinking agent, fly ash, alkali accelerator, thermal initiator, water-retaining agent, water; Acrylamide accounts for 40-80 parts by weight; Crosslinking agent 0.07~0.14 parts; 75-150 parts fly ash; 24 parts of alkali accelerator; 0.93~1.86 parts of thermal initiator; 17-68 parts of water-retaining agent; 300 portions of water.

[0007] Preferably, the crosslinking agent is N,N-methylenebisacrylamide.

[0008] Preferably, the fly ash is grade I ash with a particle size of 3~8μm.

[0009] Preferably, the alkali accelerator is sodium hydroxide.

[0010] Preferably, the thermal initiator is one or more of potassium persulfate and ammonium persulfate.

[0011] Preferably, the water-retaining agent is one or more of lithium chloride and calcium chloride.

[0012] A method for preparing a water-retaining, rapid-gel sealing material includes the following steps: S1. Dissolve the water-retaining agent and the alkali accelerator in water, stir evenly, and let stand to cool to room temperature to obtain the water-retaining agent solution and the alkali accelerator solution. S2. Add acrylamide monomer, crosslinking agent, fly ash, alkali accelerator solution and thermal initiator to the water-retaining agent solution in sequence. After obtaining the mixed solution, stir and let it stand for 15~25 minutes to prepare the sealing material.

[0013] Preferably, the specific content of S1 includes: Dissolve the water-retaining agent lithium chloride in 200 parts of water and stir for 3-5 minutes; Dissolve the alkali accelerator sodium hydroxide in 100 parts of water and stir for 3-5 minutes. The number of parts of water is fixed here. The concentration is adjusted by changing the number of parts of water-retaining agent and alkali accelerator added. The stirring time in S2 is 1~3 min, and the settling time is 5~20 min.

[0014] Preferably, the concentration of lithium chloride, the water-retaining agent, in S1 is 2~8 mol / L, and the concentration of sodium hydroxide, the alkali accelerator, is 2 mol / L.

[0015] Application of a water-retaining, rapid-gel sealing material in coal mine gas sealing.

[0016] In summary, the water-retaining rapid gel sealing material and its preparation method of the present invention have the following advantages compared with traditional technologies: 1. The water-retaining rapid gel sealing material of the present invention is an organic / inorganic composite material, which is constructed with a three-dimensional network of acrylamide and filled with fly ash as aggregate, providing strength and toughness while ensuring cost. 2. The sealing material in this invention is easy to prepare and the process is simple. The initial viscosity of the slurry is low, which is convenient for grouting. After grouting, the viscosity of the slurry increases and then quickly forms an adhesive to seal the extraction hole. 3. The sealing material in this invention has excellent mechanical properties. When the coal and rock strata deform, the sealing material can deform along with them without being destroyed. At the same time, due to the presence of the water-retaining agent, the sealing material can maintain a flexible shape for a long period of time, so as to achieve long-term sealing of the gas extraction holes in the mine and avoid the situation where the gas extraction efficiency is greatly reduced due to the loss of water in the sealing material.

[0017] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 The gel time of the water-retaining rapid gel sealing material under different concentrations of lithium chloride water-retaining agent in the embodiments of the present invention; Figure 2 The stress-strain curves of the water-retaining rapid gel sealing material under different concentrations of lithium chloride water-retaining agent in the embodiments of the present invention are shown. Figure 3 The tear energy of the water-retaining rapid gel sealing material under different concentrations of lithium chloride water-retaining agent in the embodiments of the present invention; Figure 4 The water loss rate of the water-retaining rapid gel sealing material under different concentrations of lithium chloride water-retaining agent in the embodiments of the present invention is shown. Detailed Implementation

[0019] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0020] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0021] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0022] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] This invention provides a water-retaining, rapid-gel sealing material and its preparation method.

[0025] Example 1 A water-retaining, rapid-gel sealing material comprises acrylamide, a crosslinking agent, fly ash, an alkali accelerator, a thermal initiator, a water-retaining agent, and water; wherein, by mass, acrylamide accounts for 80 parts; crosslinking agent 0.14 parts; fly ash 150 parts; alkali accelerator 24 parts; thermal initiator 1.86 parts; water-retaining agent 34 parts; and water 300 parts.

[0026] Furthermore, the crosslinking agent is NN methylenebisacrylamide.

[0027] Furthermore, the fly ash is grade I ash with a particle size of 3~8 μm.

[0028] Furthermore, the alkali accelerator is sodium hydroxide.

[0029] Furthermore, the thermal initiator is potassium persulfate.

[0030] Furthermore, the water-retaining agent is lithium chloride.

[0031] Furthermore, the method includes the following steps: S1. Dissolve the water-retaining agent and the alkali accelerator in water respectively, stir evenly, and let stand to cool to room temperature to obtain the water-retaining agent solution and the alkali accelerator solution.

[0032] S2. Add acrylamide monomer, N'N-methylenebisacrylamide, fly ash, alkali accelerator solution, and thermal initiator to the water-retaining agent solution in sequence. After obtaining the mixed solution, stir and let it stand for a period of time to prepare the sealing material.

[0033] Furthermore, in S1, the water-retaining agent and the alkali accelerator are dissolved in water, specifically, the water-retaining agent lithium chloride is dissolved in 200 parts of water and stirred for 5 min; the alkali accelerator sodium hydroxide is dissolved in 100 parts of water and stirred for 5 min.

[0034] Furthermore, in S1, the concentration of the water-retaining agent lithium chloride is 4 mol / L, and the concentration of the alkali accelerator sodium hydroxide is 2 mol / L.

[0035] Furthermore, the stirring time in S2 is 3 minutes, and the settling time is 5 to 20 minutes.

[0036] Example 2 The difference between this embodiment and Embodiment 1 is that, in the composition of a water-retaining rapid gel sealing material, the water-retaining agent is 51 parts by mass.

[0037] Furthermore, in S1, the concentration of the water-retaining agent lithium chloride is 6 mol / L, and the concentration of the alkali accelerator sodium hydroxide is 2 mol / L.

[0038] Example 3 The difference between this embodiment and Embodiment 1 is that, in the composition of a water-retaining rapid gel sealing material, the water-retaining agent comprises 68 parts by mass.

[0039] Furthermore, in step 1), the concentration of the water-retaining agent lithium chloride is 8 mol / L, and the concentration of the alkali accelerator sodium hydroxide is 2 mol / L.

[0040] Example 4 The difference between this embodiment and Embodiment 1 is that, in the water-retaining rapid gel sealing material, the components by mass are: 60 parts acrylamide; 0.1 parts crosslinking agent; 112 parts fly ash; 1.4 parts thermal initiator; and 68 parts water-retaining agent.

[0041] Furthermore, the concentration of lithium chloride, the water-retaining agent, in S1 is 8 mol / L, and the concentration of sodium hydroxide, the alkali accelerator, is 2 mol / L.

[0042] Example 5 The difference between this embodiment and Embodiment 1 is that, in the water-retaining rapid gel sealing material, by mass percentage, acrylamide accounts for 40 parts; crosslinking agent 0.07 parts; fly ash 75 parts; thermal initiator 0.93 parts; and water-retaining agent 68 parts.

[0043] Furthermore, the concentration of lithium chloride, the water-retaining agent, in S1 is 8 mol / L, and the concentration of sodium hydroxide, the alkali accelerator, is 2 mol / L.

[0044] Comparative Example 1 (without water-retaining agent) A water-retaining, rapid-gel sealing material comprises acrylamide, a crosslinking agent, fly ash, an alkali accelerator, a thermal initiator, and water; wherein, by mass, acrylamide accounts for 80 parts; crosslinking agent 0.14 parts; fly ash 150 parts; alkali accelerator 24 parts; thermal initiator 1.86 parts; and water 300 parts.

[0045] Furthermore, the crosslinking agent is NN methylenebisacrylamide.

[0046] Furthermore, the fly ash is grade I ash with a particle size of 3~8 μm.

[0047] Furthermore, the alkali accelerator is sodium hydroxide.

[0048] Furthermore, the thermal initiator is potassium persulfate.

[0049] Furthermore, the method includes the following steps: S1. Dissolve the water-retaining agent and the alkali accelerator in water respectively, stir evenly, and let stand to cool to room temperature to obtain the water-retaining agent solution and the alkali accelerator solution.

[0050] S2. Add acrylamide monomer, N'N-methylenebisacrylamide, fly ash, alkali accelerator solution, and thermal initiator to the water-retaining agent solution in sequence. After obtaining the mixed solution, stir and let it stand for a period of time to prepare the sealing material.

[0051] Furthermore, in S1, the alkali accelerator is dissolved in water, specifically, sodium hydroxide is dissolved in 100 parts of water and stirred for 5 minutes.

[0052] Furthermore, the concentration of sodium hydroxide, the alkali promoter, in S1 is 2 mol / L.

[0053] Furthermore, the stirring time in S2 is 3 minutes, and the settling time is 5 to 20 minutes.

[0054] like Figure 1 As shown, the gelation time of the water-retaining rapid gel sealing material shortens with increasing lithium chloride concentration. This is because lithium chloride, as a strong water-retaining agent, significantly reduces the water activity of the system with increased concentration, intensifying the "competition" for water between polymer chains, thereby strengthening the direct interaction between polymer chains and accelerating the formation of the three-dimensional network. Before gelation, the slurry is in a liquid state with low viscosity, facilitating grouting. After grouting, the slurry viscosity increases, subsequently rapidly gelling to seal the extraction hole.

[0055] like Figure 2 As shown, with the increase of the amount of water-retaining agent lithium chloride added, the stress and strain of the water-retaining rapid gel sealing material increase. + The strong hydration effect dehydrates the polymer chains, reducing the interchain distance and forming denser physical cross-linking points in the gel network. This creates a structure with more cross-linking points and a denser network per unit volume, thus increasing the material's stress. The sealing material of this application also possesses excellent mechanical properties. When the coal and rock strata deform, the sealing material can deform along with them without being destroyed. Simultaneously, due to the presence of the water-retaining agent, the sealing material can maintain its flexible shape for a longer period, achieving long-term sealing of underground gas extraction holes. This ensures that the components have no residual deformation under repeated loading, improving the seismic stability of the building.

[0056] like Figure 3As shown, the tear energy of the water-retaining rapid gel sealing material increases with increasing lithium chloride concentration. The addition of lithium chloride creates a gel network with high energy dissipation and uniform stress distribution. In practical construction and applications, minor defects such as scratches, pores, or structural inhomogeneities inevitably occur on the material surface. High tear energy ensures that these defects will not develop into large cracks under shear, scratching, or uneven loading. It not only withstands the design load but also possesses the toughness to contain defects and inhibit damage propagation, thereby significantly improving the long-term safety, reliability, and durability of the sealing structure and ensuring long-term sealing performance in complex engineering environments.

[0057] like Figure 4 As shown, with the increase of the amount of water-retaining agent lithium chloride added, the water loss rate of the water-retaining rapid gel sealing material gradually decreases. Lithium chloride is an extremely strong hydrated salt. + It can form a very strong hydration shell with water molecules. This greatly reduces the water activity of the water inside the gel, making it more difficult for water molecules to evaporate, thus retaining the water inside the gel. This allows it to maintain a flexible shape for a longer period of time, enabling long-term sealing of gas extraction holes in mines and avoiding a significant reduction in gas extraction efficiency due to water loss from the sealing material.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A water-retaining, rapid-gel sealing material, characterized in that, Includes the following components: Acrylamide, crosslinking agent, fly ash, alkali accelerator, thermal initiator, water-retaining agent, water; Acrylamide accounts for 40-80 parts by weight; Crosslinking agent 0.07~0.14 parts; 75-150 parts fly ash; 24 parts of alkali accelerator; 0.93~1.86 parts of thermal initiator; 17-68 parts of water-retaining agent; 300 portions of water.

2. The water-retaining rapid gel sealing material according to claim 1, characterized in that, The crosslinking agent is NN methylenebisacrylamide.

3. The water-retaining rapid gel sealing material according to claim 1, characterized in that, The fly ash is grade I ash with a particle size of 3~8μm.

4. The water-retaining, rapid-gel sealing material according to claim 1, characterized in that, The alkali accelerator is sodium hydroxide.

5. The water-retaining rapid gel sealing material according to claim 1, characterized in that, The thermal initiator is one or more of potassium persulfate and ammonium persulfate.

6. The water-retaining, rapid-gel sealing material according to claim 1, characterized in that, The water-retaining agent is one or more of lithium chloride and calcium chloride.

7. A method for preparing a water-retaining rapid gel sealing material as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Dissolve the water-retaining agent and the alkali accelerator in water, stir evenly, and let stand to cool to room temperature to obtain the water-retaining agent solution and the alkali accelerator solution. S2. Add acrylamide monomer, crosslinking agent, fly ash, alkali accelerator solution and thermal initiator to the water-retaining agent solution in sequence. After obtaining the mixed solution, stir and let it stand for 15~25 minutes to prepare the sealing material.

8. The method for preparing a water-retaining rapid gel sealing material according to claim 7, characterized in that, The specific content of S1 includes: Dissolve the water-retaining agent lithium chloride in 200 parts of water and stir for 3-5 minutes; Dissolve the alkali accelerator sodium hydroxide in 100 parts of water and stir for 3-5 minutes; The stirring time in S2 is 1~3 min, and the settling time is 5~20 min.

9. The method for preparing a water-retaining rapid gel sealing material according to claim 7, characterized in that, In S1, the concentration of lithium chloride, a water-retaining agent, is 2~8 mol / L, and the concentration of sodium hydroxide, an alkali accelerator, is 2 mol / L.

10. An application of a water-retaining, rapid-gel sealing material as described in any one of claims 1 to 6, characterized in that, The water-retaining, rapid-gel sealing material is used in the coal mine gas sealing process.

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