Alkali-activated fly ash rapid gel hole sealing material as well as preparation method and application thereof

Abstract

The invention discloses an alkali-activated fly ash rapid gel hole sealing material as well as a preparation method and application thereof, and belongs to the technical field of preparation of flexible hole sealing materials for gas drilling. The invention provides an alkali-activated fly ash rapid gel hole sealing material which is prepared by the following steps: mixing a polyacrylamide hydrogel precursor solution prepared from an acrylamide monomer and a cross-linking agent with fly ash, adding an alkali accelerator and a thermal initiator, and standing. The preparation method comprises the following steps: mixing an acrylamide monomer, deionized water and a cross-linking agent to obtain a polyacrylamide hydrogel precursor solution, and mixing the polyacrylamide hydrogel precursor solution with fly ash to obtain a mixed solution; mixing sodium hydroxide and deionized water to obtain an alkali accelerant; and mixing with the mixed solution, adding a thermal initiator, standing and curing to obtain the rapid gel hole sealing material. The rapid gel hole sealing material prepared by the invention can be rapidly gelated in a short time, and can well permeate into cracks for filling; after gelling, certain obdurability is achieved, deformation is achieved along with the change of the stress effect, and long-term and efficient sealing performance is achieved.

Description

Technical Field

[0001] This invention belongs to the field of flexible sealing material preparation technology for gas boreholes, and particularly relates to an alkali-activated fly ash rapid gel sealing material, its preparation method and application. Background Technology

[0002] The sustainable development of the coal industry impacts the economic system. The combustion of coal brings severe environmental problems; solid wastes such as fly ash, if left untreated, pose harm to human health and the atmosphere. Methane gas, a byproduct of coal mining, can be a valuable clean resource when fully utilized, but it is also a gas that endangers mine safety. Therefore, to ensure mine safety and the full utilization of methane, methane drainage from coal seams in methane-rich mines is necessary.

[0003] In gas drainage, the quality of borehole sealing plays a crucial role in the gas extraction concentration. Data shows that over 80% of the air entering the drainage system passes through leaking channels in the borehole. If the air content drawn into the borehole can be reduced by 1 / 3 to 1 / 2, the pure gas extraction volume can increase by approximately two times. Currently, sealing materials used in my country are broadly classified into inorganic materials based on cement and organic materials mainly based on polyurethane. However, in practical applications, cement-based materials have long setting times, poor stability, and are prone to water loss and shrinkage. Polyurethane materials have high viscosity, making foaming speed difficult to control. Furthermore, polyurethane foam has insufficient expansion force and shrinks after solidification and cooling. This shrinkage of the sealing material can cause cracks in the surrounding rock, resulting in poor sealing performance. As coal mining depth increases, a large amount of gas is extracted, causing coal seam deformation, displacement, and depressurization. Pores around the borehole develop and expand, and under the negative pressure of the drainage process, outside air can easily enter through these pores, thus affecting gas extraction efficiency and utilization. Therefore, developing a new type of high-performance sealing material and optimizing sealing quality are essential for effective gas extraction. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes an alkali-activated fly ash rapid gel sealing material, its preparation method, and its application. The alkali-activated fly ash rapid gel sealing material prepared by this invention is a flexible gel sealing material that can rapidly gel in a short time. Before gelation, this sealing material is a low-viscosity, flowable fluid that can effectively penetrate into and fill cracks. After gelation, it maintains a certain degree of strength and toughness. During long-term construction, the material deforms according to changes in stress, achieving long-term and efficient sealing.

[0005] To achieve the above objectives, the present invention provides an alkali-activated fly ash rapid gel sealing material, wherein the rapid gel sealing material is obtained by mixing a polyacrylamide hydrogel precursor solution prepared by acrylamide monomer and crosslinking agent with fly ash, adding an alkali accelerator and a thermal initiator, and allowing it to stand and solidify.

[0006] Preferably, the crosslinking agent is N,N-methylenebisacrylamide.

[0007] Preferably, the alkali accelerator is a sodium hydroxide solution.

[0008] Preferably, the thermal initiator is potassium persulfate.

[0009] This invention also provides a method for preparing the alkali-activated fly ash rapid gel sealing material, comprising the following steps:

[0010] (1) Acrylamide monomer, deionized water and crosslinking agent are mixed to obtain polyacrylamide hydrogel precursor solution;

[0011] (2) Fly ash is mixed with the polyacrylamide hydrogel precursor solution obtained in step (1) to obtain a mixed solution;

[0012] (3) Sodium hydroxide and deionized water are mixed to obtain an alkali accelerator;

[0013] (4) The mixed solution obtained in step (2) is mixed with the alkali accelerator obtained in step (3), and then a thermal initiator is added. The mixture is allowed to stand and solidify to obtain a fast-gel sealing material.

[0014] Preferably, the ratio of the total amount of acrylamide monomer in step (1) to the total amount of deionized water in step (1) and deionized water in step (3) is 0.067-0.267 g: 1 mL; the crosslinking agent in step (1) is NN methylenebisacrylamide, and the mass ratio of NN methylenebisacrylamide to the thermal initiator in step (4) is 0.038-0.38: 1.

[0015] Preferably, the mass ratio of the fly ash in step (2) to the total amount of deionized water in step (1) and step (3) is 1-3 g: 1-3 mL.

[0016] Preferably, the concentration of sodium hydroxide in the alkali accelerator in step (3) is 2 to 10 mol / L.

[0017] Preferably, the thermal initiator in step (4) is potassium persulfate.

[0018] The present invention also provides the application of the rapid gel sealing material or the rapid gel sealing material prepared by the preparation method in filling gas extraction boreholes and / or gas extraction borehole gaps.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] This invention uses acrylamide as a monomer and N,N-methylenebisacrylamide as a crosslinking agent, with the reaction driven by a thermal initiator to prepare an acrylamide hydrogel with a three-dimensional network structure. The hydrogel is formed through free radical polymerization, exhibiting high viscosity, processability, recyclability, and certain strength and toughness. This invention uses fly ash as the basic aggregate, achieving an effective organic / inorganic combination through blending fly ash with an active gel substrate. This results in a material with gel properties, and the fly ash, upon solidification in water, improves the toughness of the gel sealing material, enhancing sealing quality while maintaining material cost and increasing sealing speed. This invention uses sodium hydroxide as an alkali accelerator. The addition of alkali reacts with the amide groups of the monomer, producing an exothermic reaction that further shortens the gel curing time. Both the alkali and fly ash accelerate the gel curing speed, and their combined effect allows the gel material to fully gel at room temperature in approximately 10 minutes.

[0021] The flexible and rapid gel sealing material prepared by this invention can effectively fill drilled cracks. Before the gel point, it is a fluid with low viscosity and certain fluidity, which can be injected simply and quickly to achieve the sealing requirements. After gelation, it still has good flexibility and extensibility. It is low in cost, has a simple preparation process and fast gelation speed, is safe to operate, and has a wide range of applications. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This describes the curing process of the flexible rapid gel sealing material in the sample vial in Example 1;

[0024] Figure 2 The curing process of the composite material in the sample bottle is shown in Comparative Example 1.

[0025] Figure 3 The curing process of the composite material in the sample bottle is shown in Comparative Example 2.

[0026] Figure 4The figures show the temperature change curves of the flexible rapid gel sealing material of Example 1 and the composite materials of Comparative Examples 1 and 2 over time. In the figures, PAM / FA / NaOH represents the flexible rapid gel sealing material of Example 1, PAM / FA represents the composite material of Comparative Example 1, and PAM / NaOH represents the composite material of Comparative Example 2.

[0027] Figure 5 The tensile fracture stress of the flexible rapid gel sealing materials in Examples 1-3 is shown in the figure. In the figure, MBA = 0.007g represents the flexible rapid gel sealing material of Example 2, MBA = 0.014g represents the flexible rapid gel sealing material of Example 10, MBA = 0.028g represents the flexible rapid gel sealing material of Example 1, MBA = 0.056g represents the flexible rapid gel sealing material of Example 11, and MBA = 0.069g represents the flexible rapid gel sealing material of Example 3.

[0028] Figure 6 The tear energy of the flexible rapid gel sealing materials in Examples 1-3 is shown in the figure. 0.007g represents the flexible rapid gel sealing material of Example 2, 0.014g represents the flexible rapid gel sealing material of Example 10, 0.028g represents the flexible rapid gel sealing material of Example 1, 0.056g represents the flexible rapid gel sealing material of Example 11, and 0.069g represents the flexible rapid gel sealing material of Example 3.

[0029] Figure 7 The figure shows the tensile fracture stress of the flexible rapid gel sealing materials of Examples 1 and 4-5. In the figure, AM=2g represents the flexible rapid gel sealing material of Example 4, AM=4g represents the flexible rapid gel sealing material of Example 5, and AM=8g represents the flexible rapid gel sealing material of Example 1.

[0030] Figure 8 The tear energy of the flexible rapid gel sealing materials of Examples 1 and 4-5 is shown in the figure. 2g represents the flexible rapid gel sealing material of Example 4, 4g represents the flexible rapid gel sealing material of Example 5, and 8g represents the flexible rapid gel sealing material of Example 1.

[0031] Figure 9 The figure shows the tensile fracture stress of the flexible rapid gel sealing materials of Examples 1 and 6-9. In the figure, H2O:FA = 2:1 represents the flexible rapid gel sealing material of Example 1, H2O:FA = 3:2 represents the flexible rapid gel sealing material of Example 6, H2O:FA = 1:1 represents the flexible rapid gel sealing material of Example 7, H2O:FA = 2:3 represents the flexible rapid gel sealing material of Example 8, and H2O:FA = 1:2 represents the flexible rapid gel sealing material of Example 9.

[0032] Figure 10 The tear energy of the flexible rapid gel sealing materials of Examples 1 and 6-9 is shown in the figure. 2:1 represents the flexible rapid gel sealing material of Example 1, 3:2 represents the flexible rapid gel sealing material of Example 6, 1:1 represents the flexible rapid gel sealing material of Example 7, 2:3 represents the flexible rapid gel sealing material of Example 8, and 1:2 represents the flexible rapid gel sealing material of Example 9. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] Example 1

[0039] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0040] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0041] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0042] The flexible rapid gel sealing material prepared in Example 1, after curing, was used to cut dumbbell-shaped gel samples from the gel film using a cutter. Tensile and tear performance tests were then conducted at room temperature using a universal tensile testing machine. The flexible rapid gel sealing material prepared in Example 1 was then prepared, and its temperature change during curing was monitored using a thermocouple. The thermocouple's temperature probe was inserted into the gel, and the temperature was recorded every 30 seconds. Recording was stopped after curing was complete, and the recorded temperature values ​​were analyzed over time for exothermic testing. A small portion of the prepared uncured flexible rapid gel sealing material was placed in a sample bottle, and the changes in its appearance over time were observed.

[0043] Test results are as follows Figure 5 As shown, Figure 5 The MBA value of 0.028g represents the flexible rapid gel sealing material prepared in Example 1. It exhibits a tensile fracture stress of 0.21 MPa and a fracture strain of 755.65%, demonstrating certain strength and toughness, and excellent tensile properties. Based on the temperature-time evolution curve, as shown... Figure 4 As shown, Figure 4 The PAM / FA / NaOH in the middle represents the flexible rapid gel sealing material prepared in Example 1, which completes rapid curing in a short time (about 13 minutes), and the final curing temperature is significantly higher than the initial temperature. Figure 1 As shown, based on the surface morphology of the sample vials, it can be observed that the flexible rapid gel sealing material reaches a semi-gel state in about 5 minutes, with a fast gelation speed. The flexible rapid gel sealing material is finally cured in about 13 minutes.

[0044] like Figure 6As shown, 0.028g represents the flexible rapid gel sealing material prepared in Example 1, with a tear energy of 0.21kJ / m. 2 .like Figure 7 As shown, AM = 8g represents the flexible rapid gel sealing material of Example 1. (As...) Figure 8 As shown, 8g represents the flexible rapid gel sealing material of Example 1. (As...) Figure 9 As shown, H2O:FA = 2:1 represents the flexible rapid gel sealing material of Example 1. (As...) Figure 10 As shown, 2:1 represents the flexible rapid gel sealing material of Example 1.

[0045] Example 2

[0046] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.0070g (adjusted from 0.006954g according to the accuracy of the scale) of NNmethylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0047] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0048] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0049] Test results are as follows Figure 5 As shown, Figure 5 In Example 2, MBA = 0.007g represents the flexible rapid gel sealing material with a tensile fracture stress of 0.45MPa and a fracture strain of 2380.48%, exhibiting certain strength and toughness, and excellent tensile properties. Figure 6 As shown, 0.007g represents the flexible rapid gel sealing material prepared in Example 2, with a tear energy of 0.72kJ / m. 2 .

[0050] Example 3

[0051] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.06954g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0052] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0053] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0054] Test results are as follows Figure 5 As shown, Figure 5 The MBA value of 0.069g represents the flexible rapid gel sealing material prepared in Example 3. It exhibits a tensile fracture stress of 0.19 MPa and a fracture strain of 496.75%, demonstrating certain strength and toughness, and excellent tensile properties. Figure 6 As shown, 0.069g represents the flexible rapid gel sealing material prepared in Example 3, with a tear energy of 0.11kJ / m. 2 .

[0055] Example 4

[0056] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 2g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0057] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0058] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0059] like Figure 7 As shown, AM = 2g represents the flexible rapid gel sealing material of Example 4, with a tensile fracture stress of 0.08MPa and a fracture strain of 1010.64%.

[0060] like Figure 8 As shown, 2g represents the flexible rapid gel sealing material of Example 4, with a tear energy of 0.09kJ / m. 2 .

[0061] Example 5

[0062] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 4g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0063] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0064] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0065] like Figure 7 As shown, AM = 4g represents the flexible rapid gel sealing material of Example 5, with a tensile fracture stress of 0.17MPa and a fracture strain of 1451.52%.

[0066] like Figure 8 As shown, 4g represents the flexible rapid gel sealing material of Example 5, with a tear energy of 0.11kJ / m. 2 .

[0067] Example 6

[0068] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0069] (2) Weigh 20g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0070] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0071] like Figure 9 As shown, H2O:FA = 3:2 represents the flexible rapid gel sealing material of Example 6, with a tensile fracture stress of 0.24 MPa and a fracture strain of 936.49%. Figure 10 As shown, 3:2 represents the flexible rapid gel sealing material of Example 6, with a tear energy of 0.27 kJ / m. 2 .

[0072] Example 7

[0073] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0074] (2) Weigh 30g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0075] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0076] like Figure 9 As shown, H2O:FA = 1:1 represents the flexible rapid gel sealing material of Example 7, with a tensile fracture stress of 0.18 MPa and a fracture strain of 477.06%. Figure 10 As shown, 1:1 represents the flexible rapid gel sealing material of Example 7, with a tear energy of 0.28 kJ / m. 2 .

[0077] Example 8

[0078] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0079] (2) Weigh 45g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0080] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0081] like Figure 9 As shown, H2O:FA = 2:3 represents the flexible rapid gel sealing material of Example 8, with a tensile fracture stress of 0.31 MPa and a fracture strain of 752.84%. Figure 10 As shown, 2:3 represents the flexible rapid gel sealing material of Example 8, with a tear energy of 0.77 kJ / m. 2 .

[0082] Example 9

[0083] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0084] (2) Weigh 60g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0085] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0086] like Figure 9 As shown, H2O:FA = 1:2 represents the flexible rapid gel sealing material of Example 9, with a tensile fracture stress of 0.27 MPa and a fracture strain of 418.15%. Figure 10 As shown, 1:2 represents the flexible rapid gel sealing material of Example 9, with a tear energy of 0.83 kJ / m. 2 .

[0087] Example 10

[0088] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.014g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0089] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0090] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0091] Test results are as follows Figure 5 As shown, Figure 5 The MBA value of 0.014g represents the flexible rapid gel sealing material prepared in Example 10. It exhibits a tensile fracture stress of 0.31 MPa and a fracture strain of 1270.53%, demonstrating certain strength and toughness, and excellent tensile properties. Figure 6As shown, 0.014g represents the flexible rapid gel sealing material prepared in Example 10, with a tear energy of 0.39kJ / m. 2 .

[0092] Example 11

[0093] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.056g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0094] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0095] (3) Preparation of flexible rapid gel sealing material: Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved and let stand. Wait for curing at room temperature.

[0096] Test results are as follows Figure 5 As shown, Figure 5 The MBA value of 0.056g represents the flexible rapid gel sealing material prepared in Example 11. It exhibits a tensile fracture stress of 0.23 MPa and a fracture strain of 458.09%, demonstrating certain strength and toughness, and excellent tensile properties. Figure 6 As shown, 0.056g represents the flexible rapid gel sealing material prepared in Example 11, with a tear energy of 0.15kJ / m. 2 .

[0097] Comparative Example 1

[0098] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0099] (2) Weigh 15g of fly ash, pour it into the pre-prepared polyacrylamide hydrogel precursor solution, stir with a glass rod until completely dissolved, and obtain a mixed solution. Let it stand at room temperature for later use.

[0100] (3) Weigh 0.183g of potassium persulfate, add it to the mixed solution, stir with a glass rod until completely dissolved, let stand, and wait for curing at room temperature to obtain the composite material.

[0101] The composite material prepared in Comparative Example 1 was prepared, and the temperature change during the curing process was monitored by thermocouples. The temperature probe of the thermocouple was inserted into the composite material, and the temperature was recorded every 30 seconds. The recording was stopped after the curing was completed. The recorded temperature values ​​were analyzed over time to perform an exothermic test. A small portion of the prepared uncured composite material was placed in a sample bottle, and the changes in the appearance morphology of the composite material over time were observed.

[0102] Test results show that, based on the temperature evolution curve over time, such as Figure 4 As shown, Figure 4 In the example, PAM / FA represents the composite material prepared in Comparative Example 1. After a period of time, the temperature began to rise slightly, the heating rate was relatively slow, and the final temperature decreased. For example... Figure 2 As shown, based on the appearance of the sample bottle, it can be observed that the composite material remains in a solution state at 5 min, accompanied by the stratification of fly ash in the solution, and the gelation rate slows down. At around 13 min, the stratification of fly ash in the gel solution becomes more obvious, and no gel formation is found in the bottle.

[0103] Comparative Example 2

[0104] (1) Preparation of polyacrylamide hydrogel precursor solution: Weigh 8g of acrylamide monomer and add it to a beaker containing 20mL of deionized water. Stir with a glass rod until completely dissolved. Weigh 0.028g of N-N-methylenebisacrylamide and add it to the beaker. Stir with a glass rod until completely dissolved. This is the polyacrylamide hydrogel precursor solution. Then, let the solution stand at room temperature for later use.

[0105] (2) Weigh 2.4g of sodium hydroxide and measure 10mL of deionized water. Dissolve the sodium hydroxide in the deionized water and stir thoroughly until completely dissolved to obtain a sodium hydroxide solution. Add the sodium hydroxide solution to the mixed solution and stir to mix the two. Weigh 0.183g of potassium persulfate and add it to the mixed solution. Stir with a glass rod until completely dissolved. Let stand and wait for curing at room temperature to obtain the composite material.

[0106] The composite material prepared in Comparative Example 2 was prepared, and the temperature change during the curing process was monitored using a thermocouple. The temperature probe of the thermocouple was inserted into the composite material, and the temperature was recorded every 30 seconds. The recording was stopped after the curing was completed. The recorded temperature values ​​were analyzed over time to perform an exothermic test. A small portion of the prepared uncured composite material was placed in a sample bottle, and the changes in the appearance morphology of the composite material over time were observed.

[0107] Test results show that, based on the temperature evolution curve over time, such as Figure 4 As shown, Figure 4 The PAM / NaOH in the middle represents the composite material prepared in Comparative Example 2. After 30 minutes of observation, no significant temperature rise was observed. Figure 3 As shown, based on the appearance of the sample vials, it can be observed that the composite material remained in a clear solution state at 5 min and at around 13 min, the composite material was still in a clear solution state, and no gel appeared.

[0108] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A rapid gel sealing material for alkali-activated fly ash, characterized by, The quick-gel sealing material is prepared by mixing the polyacrylamide hydrogel precursor solution prepared from acrylamide monomer and crosslinking agent with fly ash, adding alkali promoter and thermal initiator, and standing for solidification.

2. The rapid gel sealant of claim 1, wherein The crosslinking agent is N-N methylene bisacrylamide.

3. The rapid gel sealant of claim 1, wherein The alkali promoter is sodium hydroxide solution.

4. The rapid gel sealant of claim 1, wherein The thermal initiator is potassium persulfate.

5. The method for preparing the alkali-activated fly ash rapid gel sealing material according to any one of claims 1-4, characterized in that, The method comprises the following steps: (1) mixing acrylamide monomer, deionized water and crosslinking agent to obtain a polyacrylamide hydrogel precursor solution; (2) mixing fly ash with the polyacrylamide hydrogel precursor solution obtained in step (1) to obtain a mixed solution; (3) mixing sodium hydroxide and deionized water to obtain an alkali promoter; (4) mixing the mixed solution obtained in step (2) with the alkali promoter obtained in step (3), then adding a thermal initiator, and standing for solidification to obtain a quick-gel sealing material.

6. The preparation method according to claim 5, characterized in that, The ratio of the acrylamide monomer in step (1) to the total amount of deionized water in step (1) and deionized water in step (3) is 0.067-0.267 g: 1 mL; the crosslinking agent in step (1) is N-N methylene bisacrylamide, and the mass ratio of the N-N methylene bisacrylamide to the thermal initiator in step (4) is 0.038-0.38:

1.

7. The preparation method according to claim 5, characterized in that, The ratio of the fly ash in step (2) to the total amount of deionized water in step (1) and deionized water in step (3) is 1-3 g: 1-3 mL.

8. The preparation method according to claim 5, characterized in that, The concentration of sodium hydroxide in the alkali promoter in step (3) is 2-10 mol / L.

9. The preparation method according to claim 5, characterized in that, The thermal initiator in step (4) is potassium persulfate.

10. The quick-gel sealing material of any one of claims 1-4 or the quick-gel sealing material prepared by the method of any one of claims 5-9 is applied in filling gas extraction boreholes and / or gaps in gas extraction boreholes.

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