Solid waste-based filling and plugging material and preparation method thereof

Abstract

According to the solid waste-based filling and plugging material and the preparation method thereof, the plugging material uses the organic additive, and the organic additive forms a'chelating dispersion-active site induction-interface bridging 'ternary enhanced network through an intermolecular synergistic effect, so that the prepared plugging material realizes mineralization-hydration synergistic enhancement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste resource utilization, and in particular to a solid waste-based filling and plugging material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the coal industry, coal-based solid wastes such as coal gangue and fly ash are accumulated in large quantities, which not only occupies land resources but also pollutes the environment. Using coal-based solid wastes to prepare filling and plugging materials is one of the important ways to realize the resource utilization of solid wastes.

[0003] At present, the commonly used solid waste-based filling and plugging materials mainly rely on the hydration of cement to achieve cementation, but the pure hydration has problems such as low early strength and insufficient durability. SUMMARY

[0004] The solid waste-based filling and plugging material and the preparation method thereof provided by the embodiments of the present application use an organic additive, the organic additive forms a ternary enhanced network of "chelation dispersion-active site induction-interface bridging" through intermolecular synergistic effect, so that the prepared plugging material realizes mineralization-hydration synergistic enhancement.

[0005] In a first aspect, the present application provides a solid waste-based filling and plugging material, which comprises the following components: coal-based solid waste, cement and organic additive; wherein the organic additive comprises the following components: carboxymethyl chitosan, polyethylene glycol modified maleic anhydride copolymer and amino glucosamine modified acrylic acid ester copolymer.

[0006] In some embodiments, the components in the solid waste-based filling and plugging material comprise, by mass fraction: coal-based solid waste 70-90 parts, cement 5-15 parts and organic additive 1-3 parts.

[0007] In some embodiments, the coal-based solid waste comprises at least one of coal gangue and fly ash.

[0008] In some embodiments, the mass ratio of carboxymethyl chitosan, polyethylene glycol modified maleic anhydride copolymer and amino glucosamine modified acrylic acid ester copolymer in the organic additive is 5:3:2.

[0009] In a second aspect, the present application provides a preparation method of a solid waste-based filling and plugging material, which comprises:

[0010] The coal-based solid waste is crushed to a preset particle size to obtain a coal-based solid waste powder;

[0011] The organic additive is prepared;

[0012] adding the coal-based solid waste powder, cement and organic additive into a blender to stir uniformly to obtain a mixture; adding water to the mixture and stirring until a uniform slurry is formed; wherein the weight of the water is 10-20% of the weight of the mixture;

[0013] placing the slurry in a sealed container and introducing carbon dioxide gas to perform mineralization modification to obtain a solid waste-based filling and plugging material.

[0014] In some embodiments, the step of preparing the organic additive comprises:

[0015] Preparation of carboxymethyl chitosan, preparation of polyethylene glycol modified maleic anhydride copolymer, and preparation of glucosamine modified acrylate copolymer.

[0016] In some embodiments, the step of preparing the carboxymethyl chitosan comprises:

[0017] adding chitosan to a sodium hydroxide solution with a mass fraction of 20-30%, stirring until dissolved to obtain a chitosan alkali solution;

[0018] after adding 10 ml of chloroacetic acid to the chitosan alkali solution, reacting at 50-60°C for 2-3 h;

[0019] after the reaction is completed, pouring the reaction liquid obtained by the reaction into ethanol, and after the steps of precipitating, filtering, washing and drying, obtaining carboxymethyl chitosan.

[0020] In some embodiments, the step of preparing the polyethylene glycol modified maleic anhydride copolymer comprises:

[0021] adding maleic anhydride and polyethylene glycol to a reactor in a molar ratio of 1:1-2, reacting at 120-140°C for 3-4 h under nitrogen protection to obtain a polyethylene glycol modified maleic anhydride copolymer.

[0022] In some embodiments, the step of preparing the glucosamine modified acrylate copolymer comprises:

[0023] adding acrylate, glucosamine and benzoyl peroxide to toluene in a mass ratio of 10:1:0.1, reacting at 60-80°C for 4-5 h;

[0024] after the reaction is completed, distilling off the toluene to obtain a glucosamine modified acrylate copolymer.

[0025] In some embodiments, the introduction pressure of the carbon dioxide gas is 0.1-0.3 MPa; the temperature of the mineralization modification is 20-40°C, and the mineralization time is 20-60 min.

[0026] The application provides a solid waste-based filling and plugging material and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 An exemplary flow chart of a preparation method of a solid waste-based filling and plugging material according to some embodiments is shown. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solutions, the technical solutions of the application will be described in detail below through specific embodiments.

[0029] With the rapid development of the coal industry, a large amount of coal-based solid waste such as coal gangue and fly ash is accumulated, which not only occupies land resources but also pollutes the environment. Using coal-based solid waste to prepare filling and plugging materials is one of the important ways to realize the resource utilization of solid waste.

[0030] At present, the commonly used solid waste-based filling and plugging materials mainly rely on the hydration of cement to achieve cementation, but the pure hydration has problems such as low early strength and insufficient durability. In addition, the traditional CO2 mineralization technology mainly uses a curing box for mineralization, and the mineralization efficiency is low and the reaction is not sufficient. The existing organic admixtures still have deficiencies in the synergistic promotion of mineralization enhancement effect and cementation performance, and the preparation methods of some admixtures are relatively complex and have high cost.

[0031] In order to solve the above technical problems, the application provides a solid waste-based filling and plugging material and a preparation method thereof. The plugging material uses an organic admixture, and the organic admixture forms a ternary enhancement network of "chelation dispersion-active site induction-interfacial bridging" through intermolecular synergistic effect, so that the prepared plugging material realizes mineralization-hydration synergistic enhancement.

[0032] In the application, the solid waste-based filling and plugging material comprises the following components: coal-based solid waste, cement and organic admixture; wherein the organic admixture comprises the following components: carboxymethyl chitosan, polyethylene glycol modified maleic anhydride copolymer and amino glucosamine modified acrylic acid ester copolymer. The coal-based solid waste comprises at least one of coal gangue and fly ash.

[0033] In the solid waste-based filling and plugging material system, the three components of the organic admixture form a ternary enhancement network of "chelation dispersion-active site induction-interfacial bridging" through intermolecular synergistic effect, and the action mechanism thereof with the coal-based solid waste and the cement presents the following hierarchical synergistic effect:

[0034] 1. Molecular level synergy among three components in organic admixture

[0035] Hydrogen bonding (i.e., chelate dispersion) between carboxymethyl chitosan and polyethylene glycol modified maleic anhydride copolymer: Carboxyl groups (-COOH) on carboxymethyl chitosan molecular chains and ether bonds (-O-) in polyethylene glycol modified maleic anhydride copolymer form a flexible network structure through hydrogen bonding, which on one hand wraps cement particles to slow down the hydration rate (to give more time for mineralization reaction), and on the other hand improves the fluidity of the slurry (which is formed in the following specific process) formed by coal-based solid waste powder, cement and organic admixture, so that CO2 bubbles are more evenly distributed in the slurry (the average bubble size is reduced from 50 μm in traditional systems to below 20 μm).

[0036] Interface anchoring effect of glucosamine modified acrylate copolymer: The amino groups (-NH2) of glucosamine modified acrylate copolymer can form ionic bonds with the carboxyl groups of carboxymethyl chitosan, while the ester groups (-COO-) can produce polar adsorption with the carboxyl groups of polyethylene glycol modified maleic anhydride copolymer, forming a "core-shell" adsorption layer on the surface of coal-based solid waste particles (i.e., active site induction). The inner core of glucosamine modified acrylate copolymer forms a covalent bond with the surface silanol groups (-SiOH) of coal-based solid waste through condensation reaction, and the outer shell of carboxymethyl chitosan-polyethylene glycol modified maleic anhydride copolymer wraps the particles through hydrogen bonding and electrostatic interaction (i.e., interface bridging), which significantly enhances the CO2 mineralization reaction activity by increasing the hydrophilicity of the coal-based solid waste particle surface by 30%.

[0037] 2. Hydration regulation mechanism of admixture and cement

[0038] Calcium ion chelation and slow release effect of carboxymethyl chitosan: The carboxyl groups of carboxymethyl chitosan can chelate calcium ions (Ca2+) in the early stage of cement hydration, and the chelated calcium ions are released slowly in the subsequent hydration process, which can effectively reduce the concentration of free calcium ions in the early stage of cement hydration, and delay the rapid formation of ettringite and C-S-H gel, leaving more calcium hydroxide for subsequent mineralization reactions. 2+ Forming a five-membered ring chelate [Ca(CC)2] 2- , reducing the concentration of free calcium ions in the early stage of cement hydration, and delaying the rapid formation of ettringite and C-S-H gel, leaving more calcium hydroxide for subsequent mineralization reactions. 2+

[0039] Hydration product directional guidance of polyethylene glycol modified maleic anhydride copolymer: The long-chain ether groups of polyethylene glycol modified maleic anhydride copolymer are adsorbed on the surface of C-S-H gel (which is generated by cement after adding water), promoting the transformation of the gel from amorphous structure to fibrous crystal. This oriented growth of the gel network forms a "cement hydration crystal nucleus-mineralization crystal" interlocking structure with the mineralization generated calcite crystals.

[0040] 3. Mineralization enhancement mechanism of admixture and coal-based solid waste ​

[0041] Active site multiplication effect of glucosamine modified acrylate copolymer: the glucosamine residues in the glucosamine modified acrylate copolymer molecule contain free amino groups, which act as CO adsorption sites during mineralization, promoting carbon sequestration through the following reaction:

[0042] -NH2+ CO2+ H2O→-NH3 + +HCO3 -

[0043] The generated HCO3- reacts with Ca 2+ released by cement hydration to form calcium carbonate, increasing the amount of carbon sequestration by 20%-30% compared to a single additive system.

[0044] In some embodiments, the solid waste-based filling and plugging material comprises, in parts by mass: coal-based solid waste 70-90 parts, cement 5-15 parts, and organic additive 1-3 parts. In the embodiments of the present application, the reason for setting the fraction of the components is that if the coal-based solid waste is higher than 90 parts, it will lead to the strength required for filling and plugging cannot be achieved regardless of mineralization and hydration, and if it is too low, it may need to increase the amount of other components, resulting in high cost. The amount of cement will increase the cost of the plugging material, and too low will not reach the corresponding strength. Too high and too low of the organic additive will not achieve the mineralization enhancement effect, and too high will also increase the cost.

[0045] In some embodiments, the mass ratio of carboxymethyl chitosan, polyethylene glycol modified maleic anhydride copolymer, and glucosamine modified acrylate copolymer in the organic additive is 5:3:2.

[0046] In the embodiments of the present application, the setting of the mass ratio of 5:3:2 allows the carboxymethyl chitosan, polyethylene glycol modified maleic anhydride copolymer, and glucosamine modified acrylate copolymer to play a better synergistic enhancement effect, and deviating from this ratio will greatly reduce the synergistic effect.

[0047] The embodiments of the present application also provide a preparation method of a solid waste-based filling and plugging material, Figure 1 An exemplary flowchart of a preparation method of a solid waste-based filling and plugging material according to some embodiments is shown. The method comprises S100-S400.

[0048] S100, crushing coal-based solid waste to a predetermined particle size to obtain coal-based solid waste powder.

[0049] In some embodiments, the predetermined particle size is less than 0.1 mm, so that the coal-based solid waste powder obtained can fully react with other components.

[0050] S200, preparing an organic additive.

[0051] In some embodiments, the step of preparing the organic admixture comprises:

[0052] Preparation of carboxymethyl chitosan, preparation of polyethylene glycol modified maleic anhydride copolymer, and preparation of glucosamine modified acrylate copolymer.

[0053] In some embodiments, the step of preparing the carboxymethyl chitosan comprises:

[0054] Chitosan is added to a sodium hydroxide solution with a mass fraction of 20%-30%, stirred until dissolved, to obtain a chitosan alkali solution;

[0055] After adding 10ml chloroacetic acid to the chitosan alkali solution, reaction at 50-60℃ for 2-3h;

[0056] After the reaction is completed, the reaction liquid obtained by the reaction is poured into ethanol, and after the steps of precipitating, filtering, washing and drying, carboxymethyl chitosan is obtained.

[0057] In the embodiments of the present application, based on the above process parameters, carboxymethyl chitosan can be prepared to the greatest extent, reducing the generation of by-products such as carboxyethyl or propyl chitosan, and exceeding the above process will result in a large amount of by-products.

[0058] In some embodiments, the step of preparing the polyethylene glycol modified maleic anhydride copolymer comprises:

[0059] Maleic anhydride and polyethylene glycol are added to the reactor in a molar ratio of 1:1-2, and reacted at 120-140℃ for 3-4h under nitrogen protection to obtain a polyethylene glycol modified maleic anhydride copolymer.

[0060] In some embodiments, the step of preparing the glucosamine modified acrylate copolymer comprises:

[0061] Acrylate, glucosamine and benzoyl peroxide are added to toluene in a mass ratio of 10:1:0.1, and reacted at 60-80℃ for 4-5h;

[0062] After the reaction is completed, toluene is removed by distillation to obtain a glucosamine modified acrylate copolymer.

[0063] S300, the coal-based solid waste powder, cement and organic admixture are added to a blender and stirred uniformly to obtain a mixture; water is added to the mixture and stirred until a uniform slurry is formed; wherein the weight of the water is 10%-20% of the weight of the mixture.

[0064] In the embodiments of the present application, the weight of water is 10%-20% of the weight of the mixture. The reason for setting this range is that the water content in this range can make the slurry maintain good fluidity and strength. Too much water content can make the slurry have good concentration, but more cement or more additives need to be added to maintain the same strength. Too little water content can reduce the fluidity of the slurry and make it difficult to pump.

[0065] S400, placing the slurry in a sealed container, introducing carbon dioxide gas for mineralization modification, to obtain a solid waste-based filling and plugging material.

[0066] In some embodiments, the introduction pressure of the carbon dioxide gas is 0.1-0.3 MPa; the temperature of the mineralization modification is 20-40℃, and the mineralization time is 20-60 min. Under this process parameter, the mineralization enhancement effect is the best.

[0067] The solid waste-based filling and plugging material in the embodiments of the present application is a mineralization-hydration synergistically enhanced solid waste-based filling and plugging material.

[0068] The components of the solid waste-based filling and plugging material are described in the form of a table as follows: Table 1, in which cc represents carboxymethyl chitosan, AGA represents amino glucose modified acrylate copolymer, and PEG-MA represents polyethylene glycol modified maleic anhydride copolymer. Single, binary and ternary represent the composition types of organic additives. Mixed waste solid refers to coal-based solid waste, including coal gangue and fly ash. The preparation process parameters are the same except for the raw materials in the examples and comparative examples.

[0069] Table 1

[0070]

[0071]

[0072] From the content of Table 1, it can be seen that the carbon sequestration amount (28%) of the ternary system of Example 1 is higher than that of Comparative Example 1 (without additive) when the cement dosage is only 5 parts, which proves that the synergistic effect of the additive can still effectively promote mineralization under low cement dosage.

[0073] From the comparison of Example 1 (three kinds of additives are added together) and Comparative Examples 2-6 (single / binary additive), it can be seen that the carbon sequestration amount (28%) of the ternary system is still higher than that of Comparative Examples 2-6 although the cement dosage is the lowest (5 parts). This shows that the three kinds of additives realize "high performance cementation under low cement dosage" through the four mechanisms of "delaying hydration-regulating crystal form-enhancing mineralization-interfacial cementation", breaking through the limitation of traditional systems relying on high cement dosage.

[0074] In conclusion, the application provides a kind of solid waste-based filling plugging material and its preparation method, the plugging material uses organic additive, the organic additive forms ternary enhanced network of " chelation dispersion-active site induction-interface bridging" by intermolecular synergistic effect, so that the prepared plugging material realizes mineralization-hydration synergistic enhancement.

[0075] Those skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict. The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above is only a preferred embodiment of the present application, and it should be pointed out that, for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can also be made, which should be regarded as the protection scope of the present application.

Claims

1. A solid waste-based filling and plugging material, characterized in that: The solid waste-based filling and plugging material comprises the following components: coal-based solid waste, cement and organic admixtures; wherein the organic admixtures comprise the following components: carboxymethyl chitosan, polyethylene glycol-modified maleic anhydride copolymer and glucosamine-modified acrylate copolymer.

2. The solid waste-based filling and plugging material according to claim 1, characterized in that: The components of the solid waste-based filling and plugging material include, by mass, 70-90 parts of coal-based solid waste, 5-15 parts of cement, and 1-3 parts of organic admixture.

3. The solid waste-based filling and plugging material according to claim 1, characterized in that: The coal-based solid waste includes at least one of coal gangue and fly ash.

4. The solid waste-based filling and plugging material according to claim 1, characterized in that: The mass ratio of carboxymethyl chitosan, polyethylene glycol-modified maleic anhydride copolymer and glucosamine-modified acrylate copolymer in the organic additive is 5:3:

2.

5. The method for preparing the solid waste-based filling and plugging material according to any one of claims 1 to 4, characterized in that: include: Grinding the coal-based solid waste to a predetermined particle size to obtain coal-based solid waste powder; Preparation of organic admixtures; The coal-based solid waste powder, cement and organic admixture are added to a mixer and stirred uniformly to obtain a mixture; water is added to the mixture and stirred until a uniform slurry is formed; wherein the weight of the water is 10% to 20% of the weight of the mixture; The slurry is placed in a sealed container, and carbon dioxide gas is introduced to perform mineralization modification to obtain a solid waste-based filling and plugging material.

6. The method according to claim 5, characterized in that The steps of preparing the organic admixture include: Preparation of carboxymethyl chitosan, preparation of polyethylene glycol-modified maleic anhydride copolymer, and preparation of glucosamine-modified acrylate copolymer.

7. The method according to claim 6, characterized in that The step of preparing carboxymethyl chitosan comprises: Add chitosan to a sodium hydroxide solution having a mass fraction of 20% to 30%, and stir until dissolved to obtain a chitosan alkaline solution; After adding 10 ml of chloroacetic acid to the chitosan alkaline solution, react at 50-60° C. for 2-3 hours; After the reaction is completed, the reaction solution is poured into ethanol, and carboxymethyl chitosan is obtained after the steps of precipitation, filtration, washing and drying.

8. The method according to claim 6, characterized in that The steps of preparing the polyethylene glycol-modified maleic anhydride copolymer include: Maleic anhydride and polyethylene glycol were added into the reactor in a molar ratio of 1:1-2, and reacted at 120-140° C. for 3-4 hours under nitrogen protection to obtain a polyethylene glycol-modified maleic anhydride copolymer.

9. The method according to claim 6, characterized in that The steps of preparing the glucosamine-modified acrylate copolymer include: Add acrylate, glucosamine and benzoyl peroxide to toluene at a mass ratio of 10:1:0.1 and react at 60-80°C for 4-5 hours; After the reaction was completed, toluene was distilled off to obtain a glucosamine-modified acrylate copolymer.

10. The method according to claim 6, characterized in that The pressure of the carbon dioxide gas introduced is 0.1-0.3 MPa; the temperature of the mineralization modification is 20-40° C., and the mineralization time is 20-60 min.

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