Mineralized fly ash-based cementitious filling material resistant to mine water corrosion and preparation method thereof

Abstract

The present invention discloses a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. The filling material, with mineralized fly ash as its core, utilizes the synergistic effects of multiple components in a composite activator and an anti-corrosion agent to enhance the filling material's strength and corrosion resistance. The method comprises premixing the raw materials, activating and modifying the materials, and finally mixing and packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of filling materials, and in particular to a mineralized fly ash-based gelling filling material resistant to mine water corrosion and a preparation method thereof. Background Art

[0002] Currently, backfill materials used in mines are often corroded by mine water. This corrosion weakens the backfill material, reducing its support capacity, potentially causing mine collapse or rock shifting, and endangering miner safety. Therefore, enhancing the corrosion resistance of backfill materials has become a pressing technical challenge for those skilled in the art. Summary of the Invention

[0003] This application provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. This filling material, with mineralized fly ash as its core, utilizes the synergistic effects of multiple components in a composite activator and corrosion inhibitor to enhance the filling material's strength and corrosion resistance. The method includes premixing the raw materials, activating and modifying them, and finally mixing and packaging them.

[0004] The present invention provides a method for preparing a mineralized fly ash-based cementitious filling material resistant to mine water corrosion, comprising:

[0005] Raw material premixing: Mix mineralized fly ash, slag powder, cement, nano silica fume and metakaolin according to the preset mass ratio;

[0006] Stimulation and modification: adding a composite activator and an anti-corrosion agent to the first mixture obtained in the raw material premixing step in sequence, and continuing to mix; wherein the composite activator comprises sulfoaluminate, calcium hydroxide, and a polyaspartic acid-EDTA derivative; and the anti-corrosion agent comprises calcium nitrate, fluorinated polysilsesquioxane, and a halloysite nanotube-carboxymethyl cellulose complex;

[0007] Final mixing and packaging: the second mixture obtained in the excitation and modification steps is stirred, and then sealed and packaged to obtain the filling material.

[0008] In some embodiments, the steps of preparing the mineralized fly ash include:

[0009] preparing fly ash into a slurry, and subjecting the slurry to a direct liquid phase mineralization reaction with CO2 gas to reduce the pH value of the slurry to 7.5;

[0010] The slurry with a pH value reduced to 7.5 is mixed with sodium lithium carbonate, cured under a wet heat condition of 60° C. for 24 hours, and dried to obtain mineralized fly ash with a porous structure.

[0011] In some embodiments, the step of preparing the fly ash into a slurry comprises:

[0012] The fly ash and water are mixed in a mass ratio of 1:1-5 to obtain the slurry.

[0013] In some embodiments, the preset mass ratio of the mineralized fly ash, slag powder, cement, nano-silica fume and metakaolin is 50-60:15-25:10-15:5-8:3-5.

[0014] In some embodiments, the mass ratio of sulfoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative in the composite activator is 2:1:0.1.

[0015] In some embodiments, the composite activator accounts for 2%-4% by mass of the mineralized fly ash.

[0016] In some embodiments, the mass ratio of calcium nitrate, fluorinated polysilsesquioxane, and halloysite nanotube-carboxymethyl cellulose composite in the corrosion inhibitor is 1:1:0.1.

[0017] In some embodiments, the anti-corrosion agent accounts for 1%-3% by mass of the mineralized fly ash.

[0018] In some embodiments, the steps of preparing the halloysite nanotube-carboxymethyl cellulose composite include:

[0019] (1) dispersing halloysite nanotubes in deionized water and ultrasonically treating the solution for 30 minutes to form a dispersion with a concentration of 1-2 mg / mL;

[0020] (2) dissolving carboxymethyl cellulose in deionized water to prepare a solution with a mass fraction of 1.0% to 2.0%; heating and stirring the solution in a 40° C. water bath to obtain a carboxymethyl cellulose solution, wherein the stirring speed in step (2) is 600 to 800 rpm and the stirring time is 30 minutes;

[0021] (3) adding the maleamide solution to the carboxymethyl cellulose solution, stirring evenly, and reacting at room temperature for 24 hours to obtain a carboxymethyl cellulose-maleamide solution;

[0022] (4) slowly adding the dispersion to the carboxymethyl cellulose-maleimide solution at a dropping speed of 30-60 drops / minute; stirring is maintained during the dropping process to obtain a composite material; wherein the stirring speed in step (4) is 600 rpm and the stirring time is 30-60 minutes;

[0023] (5) The composite material was taken out and repeatedly washed with deionized water; and dried at 60° C. for 24 hours to obtain a halloysite nanotube-carboxymethyl cellulose composite.

[0024] In some embodiments, in the final mixing and packaging step, the second mixture obtained in the excitation and modification step is stirred using a closed planetary mixer; the rotation speed of the closed planetary mixer is 500 rpm.

[0025] The embodiment of the present application also provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion, which is prepared using the preparation method of the mineralized fly ash-based cementitious filling material resistant to mine water corrosion.

[0026] The present invention provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. This filling material, with mineralized fly ash as its core, enhances its strength and corrosion resistance through the synergistic effect of multiple components in a composite activator and anti-corrosion agent. The method comprises premixing of raw materials, activation and modification, and final mixing and packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flow chart of a method for preparing a mineralized fly ash-based cementitious filling material resistant to mine water corrosion according to some embodiments is exemplified. DETAILED DESCRIPTION

[0028] In order to better understand the above technical solution, the technical solution of this application is described in detail below through specific implementation methods.

[0029] To address the aforementioned technical issues, the present invention provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. This filling material, with mineralized fly ash as its core, utilizes the synergistic effects of multiple components in a composite activator and corrosion inhibitor to enhance the filling material's strength and corrosion resistance. The method includes premixing raw materials, activation and modification, and final mixing and packaging.

[0030] Figure 1 The flowchart of a method for preparing a mineralized fly ash-based cementitious filling material resistant to mine water corrosion according to some embodiments is exemplified. The method includes S100-S300.

[0031] S100, raw material premixing: Mineralized fly ash, slag powder, cement, nano-silica fume, and metakaolin are mixed according to a preset mass ratio. For example, the mixing time may be 15 minutes.

[0032] In some embodiments, the preparation steps of the mineralized fly ash include: preparing fly ash into a slurry, reacting the slurry with CO2 gas for a direct liquid-phase mineralization reaction to reduce the pH value of the slurry to 7.5; mixing the slurry with a pH value reduced to 7.5 with sodium lithium carbonate, curing under wet heat conditions at 60°C for 24 hours, and obtaining mineralized fly ash with a porous structure after drying.

[0033] In the embodiment of the present application, sodium lithium carbonate (LiCO-NaCO) will ionize in aqueous solution to produce lithium ions (Li + ), sodium ion (Na + ), carbonate ions (CO3 2- ) etc. + and Na + With a small ionic radius and high charge density, it can exchange ions with the silicon-oxygen bonds (Si-O) and aluminum-oxygen bonds (Al-O) on the surface of fly ash particles, thereby destroying the original structure of the fly ash surface, making the active ingredients in the fly ash more easily dissolve and increasing the mineralization efficiency of the fly ash. Slag micropowder (particle size 5μm) and nano-silica fume (50nm) form a "coarse-fine-coarse" three-level particle size distribution, increasing the bulk density by 18% and reducing the permeability coefficient to 1×10 -12 m / s.

[0034] In some embodiments, the mass fraction of the sodium lithium carbonate in the fly ash is 5%.

[0035] In some embodiments, the step of preparing the fly ash into slurry includes: mixing the fly ash and water in a mass ratio of 1:1-5 to obtain the slurry.

[0036] In some embodiments, the preset mass ratio of the mineralized fly ash, slag powder, cement, nano-silica fume and metakaolin is 50-60:15-25:10-15:5-8:3-5.

[0037] In the raw material premixing step, a dry powder mixer is used to mix mineralized fly ash, slag powder, cement, nano silica fume and metakaolin according to a preset mass; the rotation speed of the dry powder mixer is 200 rpm, that is, the dry powder mixer runs at a low speed.

[0038] S200, excitation and modification: adding a composite activator and an anti-corrosion agent in sequence to the first mixture obtained in the raw material premixing step, and continuing to mix, illustratively for 10 minutes; wherein the composite activator includes sulfoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative; the anti-corrosion agent includes calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose complex.

[0039] In the embodiment of the present application, the polyaspartic acid-EDTA derivative combines with the inert Al-O-Si network in the fly ash and releases the active Al through chelation-depolymerization. 3+ and Si 4+ , accelerating the alkali excitation reaction (cooperating with Li2CO3-Na2CO3) and promoting the formation of geopolymer gel (NASH).+ 、Na + The ions and polyaspartic acid-EDTA derivatives control the release and precipitation rate of metal ions through complexation, making the formation and growth of crystal nuclei more orderly and stable, which is conducive to the generation of more and more uniform products such as calcium silicate hydrate (CSH) gel and calcium aluminate hydrate (CAH) gel, thereby improving the strength and durability of the material.

[0040] In some embodiments, the mass ratio of sulfoaluminate, calcium hydroxide, and polyaspartic acid-EDTA derivative in the composite activator is 2:1:0.1. In this embodiment, sulfoaluminate, calcium hydroxide, and polyaspartic acid-EDTA derivative are mixed in a mass ratio of 2:1:0.1 to obtain a composite activator.

[0041] In some embodiments, the composite activator accounts for 2%-4% by mass of the mineralized fly ash.

[0042] In some embodiments, the anti-corrosion agent comprises calcium nitrate, fluorinated polysilsesquioxane, and halloysite nanotube-carboxymethyl cellulose composite in a mass ratio of 1:1:0.1. In this embodiment, calcium nitrate, fluorinated polysilsesquioxane, and halloysite nanotube-carboxymethyl cellulose composite are mixed in a mass ratio of 1:1:0.1 to obtain the anti-corrosion agent.

[0043] In the examples of this application, the calcium ions of calcium nitrate in the corrosion inhibitor react with Cl- in the mine water to form CaCl·2HO crystals, which block capillary pores and achieve corrosion resistance. Fluorinated polysilsesquioxane forms a Si-O-Si hydrophobic film on the material surface with a contact angle >110°, which can provide corrosion resistance.

[0044] Halloysite nanotube-carboxymethyl cellulose composite can achieve anti-corrosion performance in multiple ways. Specifically, the halloysite nanotubes are hollow tubular structures (outer diameter 50nm, length 1-2μm), which are oriented in the cement pores to form a "maze-like" barrier, which blocks the Cl in mine water. - / SO4 2- Diffusion, achieving physical barrier. Halloysite nanotube surface is rich in Al 3+ , adsorbing SO4 through electrostatic action 2- The maleamide-modified carboxymethyl cellulose loaded in the tube chelates Cl through the carboxyl and amino groups. - The amino groups in maleamide-modified carboxymethyl cellulose induce the CaCO mineralization products in the mineralized fly ash to cross-link and grow on the surface of halloysite nanotubes, forming a dense "mineralization-nanotube" composite barrier layer to block Cl in mine water. - / SO4 2-In addition, the amino groups of maleamide-modified carboxymethyl cellulose can be oxidatively cross-linked in an alkaline environment, which can achieve self-repair of microcracks and enhance the durability of mineralized fly ash-based cementitious materials.

[0045] In some embodiments, the anti-corrosion agent accounts for 1% to 3% of the mineralized fly ash by mass. In some embodiments, the anti-corrosion agent accounts for 2% of the mineralized fly ash by mass.

[0046] In some embodiments, the preparation steps of the halloysite nanotube-carboxymethyl cellulose composite include steps (1) to (5).

[0047] (1) Dispersing the halloysite nanotubes in deionized water and ultrasonically treating the solution for 30 minutes to form a dispersion having a concentration of 1-2 mg / mL. In step (1), the halloysite nanotubes can be uniformly dispersed in the deionized water after ultrasonic treatment.

[0048] (2) dissolving carboxymethyl cellulose in deionized water to prepare a solution with a mass fraction of 1.0% to 2.0%; heating and stirring the solution in a 40° C. water bath to obtain a carboxymethyl cellulose solution, wherein the stirring speed in step (2) is 600 to 800 rpm and the stirring time is 30 minutes.

[0049] (3) adding the maleic acid amide solution to the carboxymethyl cellulose solution, stirring evenly, and reacting at room temperature for 24 hours to obtain a carboxymethyl cellulose-maleic acid amide solution.

[0050] (4) slowly adding the dispersion to the carboxymethyl cellulose-maleimide solution at a dropping speed of 30-60 drops / minute; stirring is maintained during the dropping process to obtain a composite material; wherein the stirring speed in step (4) is 600 rpm and the stirring time is 30-60 minutes;

[0051] (5) The composite material is taken out and repeatedly washed with deionized water; and dried at 60° C. for 24 hours to obtain a halloysite nanotube-carboxymethyl cellulose composite. In step (5), the composite material is repeatedly washed with deionized water to remove unreacted residues.

[0052] S300, final mixing and packaging: The second mixture obtained in the excitation and modification steps is stirred. For example, the mixture may be stirred for 20 minutes. After stirring, the mixture is sealed and packaged to obtain a filling material.

[0053] In some embodiments, in the final mixing and packaging step, the second mixture obtained in the excitation and modification step is stirred using a closed planetary mixer; the speed of the closed planetary mixer is 500 rpm, that is, the closed planetary mixer stirs the second mixture at a high speed.

[0054] The present application also provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion, which is prepared by the method for preparing the mineralized fly ash-based cementitious filling material resistant to mine water corrosion.

[0055] The present invention provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. This filling material, with mineralized fly ash as its core, utilizes the synergistic effects of multiple components in a composite activator and an anti-corrosion agent to enhance the filling material's strength and corrosion resistance. The method includes premixing the raw materials, activating and modifying them, and finally mixing and packaging them.

[0056] The following examples and comparative examples in Table 1 illustrate that the method for preparing the mineralized fly ash-based cementitious filling material resistant to mine water corrosion in the embodiments of the present application has good performance. The following examples and comparative examples all use the same process parameters, differing only in the use of raw materials. The test materials used in the following examples, unless otherwise specified, were purchased from conventional stores and other channels. The quantitative tests in the following examples were all repeated three times, and the data are the average or average ± standard deviation of the three repeated experiments.

[0057] Table 1

[0058]

[0059]

[0060] Comparing Comparative Example 1 with Example 1, it can be found that the filling material obtained from the mineralized fly ash has enhanced performance in terms of compressive strength, sulfate corrosion coefficient and Cl- penetration depth;

[0061] Comparing Comparative Example 2 with Example 1, it was found that the filling material obtained by adding nano-silica fume had enhanced performance in terms of compressive strength, sulfate corrosion coefficient and Cl- penetration depth;

[0062] Comparing Comparative Example 3 with Example 1, it was found that the filling material obtained by adding the corrosion inhibitor had enhanced performance in terms of compressive strength, sulfate corrosion coefficient, and Cl- penetration depth;

[0063] Comparing Comparative Example 4 with Example 1, it was found that the addition of calcium nitrate, fluorinated polysilsesquioxane, and halloysite nanotube-carboxymethyl cellulose composite to the corrosion inhibitor enhanced the compressive strength, sulfate corrosion coefficient, and Cl- penetration depth of the filling material compared to the corrosion inhibitor containing only calcium nitrate.

[0064] Comparing Comparative Example 5 with Example 1, it was found that the addition of cement, mineralized fly ash and slag powder to the raw materials enhanced the compressive strength, sulfate corrosion coefficient and Cl- penetration depth compared to the filling material containing only cement.

[0065] In summary, the present invention provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. This filling material, with mineralized fly ash as its core, utilizes the synergistic effects of multiple components in a composite activator and corrosion inhibitor to enhance the filling material's strength and corrosion resistance. The method includes premixing the raw materials, activating and modifying the materials, and finally mixing and packaging.

[0066] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. 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 should be included in the scope of protection of the present application. The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application. These improvements and variations should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing a mineralized fly ash-based cementitious filling material resistant to mine water corrosion, characterized in that: include: Raw material premixing: Mix mineralized fly ash, slag powder, cement, nano silica fume and metakaolin according to the preset mass ratio; Stimulation and modification: adding a composite activator and an anti-corrosion agent to the first mixture obtained in the raw material premixing step in sequence, and continuing to mix; wherein the composite activator comprises sulfoaluminate, calcium hydroxide, and a polyaspartic acid-EDTA derivative; and the anti-corrosion agent comprises calcium nitrate, fluorinated polysilsesquioxane, and a halloysite nanotube-carboxymethyl cellulose complex; Final mixing and packaging: stirring the second mixture obtained in the excitation and modification steps, and then sealing and packaging to obtain a filling material; The preparation steps of the mineralized fly ash include: preparing fly ash into slurry, subjecting the slurry to a direct liquid-phase mineralization reaction with CO2 gas to reduce the pH value of the slurry to 7.5; mixing the slurry with the pH value reduced to 7.5 with sodium lithium carbonate, curing under a wet-heat condition of 60°C for 24 hours, and drying to obtain mineralized fly ash with a porous structure; The preparation steps of the halloysite nanotube-carboxymethyl cellulose composite include: (1) dispersing halloysite nanotubes in deionized water, and ultrasonically treating for 30 minutes to form a dispersion with a concentration of 1-2 mg / mL; (2) dissolving carboxymethyl cellulose in deionized water to prepare a solution with a mass fraction of 1.0%-2.0%; heating and stirring the solution in a 40° C. water bath to obtain a carboxymethyl cellulose solution, wherein the stirring speed in step (2) is 600-800 rpm and the stirring time is 30 minutes; (3) adding the maleamide solution to the carboxymethyl cellulose; The method comprises the following steps: (1) adding the dispersion into a methyl cellulose solution, stirring the dispersion evenly, and reacting the mixture at room temperature for 24 hours to obtain a carboxymethyl cellulose-maleimide solution; (2) slowly dropping the dispersion into the carboxymethyl cellulose-maleimide solution at a dropping speed of 30-60 drops / minute; and maintaining stirring during the dropping process to obtain a composite material; wherein the stirring speed in step (4) is 600 rpm and the stirring time is 30-60 minutes; and (3) taking out the composite material, repeatedly washing the composite material with deionized water, and drying the composite material at 60°C for 24 hours to obtain a halloysite nanotube-carboxymethyl cellulose composite.

2. The method according to claim 1, characterized in that The step of preparing fly ash into slurry comprises: The fly ash and water are mixed in a mass ratio of 1:1-5 to obtain the slurry.

3. The method according to claim 1, characterized in that The preset mass ratio of the mineralized fly ash, slag powder, cement, nano-silica fume and metakaolin is 50-60:15-25:10-15:5-8:3-5.

4. The method according to claim 1, wherein The mass ratio of sulphoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative in the composite activator is 2:1:0.

1.

5. The method according to claim 4, characterized in that The mass fraction of the composite activator in the mineralized fly ash is 2%-4%.

6. The method according to claim 1, characterized in that The mass ratio of calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose composite in the corrosion inhibitor is 1:1:0.

1.

7. The method according to claim 6, characterized in that The mass fraction of the anti-corrosion agent in the mineralized fly ash is 1%-3%.

8. A mineralized fly ash-based cementitious filling material resistant to mine water corrosion, characterized in that: The mineralized fly ash-based cementitious filling material resistant to mine water corrosion is prepared by the preparation method of any one of claims 1 to 7.

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