Mineralized fly ash-based gel filling material resistant to corrosion of mine water and preparation method of mineralized fly ash-based gel filling material

Abstract

The invention discloses a mine water corrosion-resistant mineralized fly ash-based gel filling material and a preparation method thereof, the filling material takes mineralized fly ash as a core, and the strength and corrosion resistance of the filling material are improved through the synergistic effect of multiple components in a composite activator and a corrosion inhibitor. The method comprises the steps of raw material premixing, excitation and modification, and final mixing and packaging.

Description

Technical Field

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

[0002] At present, when filling materials are used in mines, they are often corroded by mine water. Corrosion will weaken the strength of the filling materials, resulting in reduced support capacity, which may cause mine collapse or rock movement, endangering the safety of miners and other problems. Therefore, how to enhance the corrosion resistance of filling materials has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0003] The present invention provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof. The filling material is based on mineralized fly ash and improves the strength and corrosion resistance of the filling material through the synergistic effect of multiple components in a composite activator and an anti-corrosion agent. The method includes: raw material premixing, activation and modification, and final mixing and packaging.

[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: mineralized fly ash, slag powder, cement, nano-silica ash and metakaolin are mixed according to the preset mass ratio;

[0006] Excitation and modification: adding a composite exciter 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 exciter comprises sulphoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative; and the anti-corrosion agent comprises calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose composite;

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

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

[0009] The fly ash is prepared into a slurry, and the slurry is mixed with CO 2 The gas undergoes a direct liquid phase mineralization reaction 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 then dried to obtain mineralized fly ash with a porous structure.

[0011] In some embodiments, the step of preparing fly ash into 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 preparation steps of the halloysite nanotube-carboxymethyl cellulose composite include:

[0019] (1) dispersing halloysite nanotubes in deionized water and subjecting the mixture to ultrasonic treatment for 30 minutes to form a dispersion having 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 dropping the dispersion into the carboxymethyl cellulose-maleamide 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 is taken out, and washed repeatedly 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 by 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, wherein the filling material is based on mineralized fly ash and the strength and corrosion resistance of the filling material are improved through the synergistic effect of multiple components in a composite activator and an anticorrosive 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 the present application is described in detail below through specific implementation methods.

[0029] In order to solve the above technical problems, the embodiment of the present application provides a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof, wherein the filling material is based on mineralized fly ash and the strength and corrosion resistance of the filling material are improved through the synergistic effect of multiple components in the composite activator and the anti-corrosion agent. The method comprises: premixing of 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 exemplarily shown. The method includes S100-S300.

[0031] S100, premixing raw materials: mixing mineralized fly ash, slag powder, cement, nano silica fume and metakaolin according to a preset mass ratio. For example, the mixing may be performed for 15 minutes.

[0032] In some embodiments, the preparation steps of the mineralized fly ash include: preparing fly ash into 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 be ionized in the aqueous solution to generate lithium ions (Li + ), sodium ion (Na + ), carbonate ions (CO 3 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 particle surface, making the active ingredients in the fly ash more easily dissolved and increasing the mineralization efficiency of the fly ash. Slag micropowder (particle size 5μm) and nano silica ash (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 to the first mixture obtained in the raw material premixing step in sequence, and continuing to mix, illustratively, the mixing can be performed for 10 minutes; wherein the composite activator includes sulfoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivatives; the anti-corrosion agent includes calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose composite.

[0039] In the present embodiment, the polyaspartic acid-EDTA derivative combines with the inert Al-O-Si network in the fly ash to release the active Al through chelation-depolymerization. 3+ and Si 4+ , accelerates the base-induced reaction (with Li 2 CO 3 -Na 2CO 3 Synergistically), promoting the formation of geopolymer gel (NASH). At the same time, the Li + 、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 sulphoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative in the composite activator is 2:1:0.1. In this embodiment, sulphoaluminate, 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 mass ratio of calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose composite in the corrosion inhibitor is 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 corrosion inhibitor.

[0043] In the embodiment of the present application, the calcium ions of calcium nitrate in the anticorrosive agent react with Cl- in the mine water to generate CaCl·2HO crystals, which block the capillary pores, thereby achieving anticorrosion performance. Fluorinated polysilsesquioxane forms a Si-O-Si hydrophobic film on the surface of the material with a contact angle of >110°, and the hydrophobic film can achieve anticorrosion performance.

[0044] Halloysite nanotube-carboxymethyl cellulose composite can achieve anti-corrosion performance in many aspects. Specifically, the halloysite nanotube is a hollow tubular structure (outer diameter 50nm, length 1-2μm), which is oriented in the cement pores to form a "maze-like" barrier, which prevents the Cl in mine water from - / SO 4 2- Diffusion, achieving physical isolation. Halloysite nanotube surface is rich in Al 3+ , adsorbing SO through electrostatic action 4 2- The maleamide-modified carboxymethyl cellulose loaded in the tube chelates Cl through the carboxyl and amine 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. - / SO 4 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%-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 steps of preparing the halloysite nanotube-carboxymethyl cellulose composite include steps (1) to (5).

[0047] (1) Dispersing the halloysite nanotubes in deionized water and subjecting the mixture to ultrasonic treatment 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 maleamide solution to the carboxymethyl cellulose solution, stirring evenly, and reacting at room temperature for 24 hours to obtain a carboxymethyl cellulose-maleamide solution.

[0050] (4) slowly dropping the dispersion into the carboxymethyl cellulose-maleamide 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, repeatedly washed with deionized water, and dried at 60° C. for 24 hours to obtain a halloysite nanotube-carboxymethyl cellulose composite. In this 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 rotation 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 preparation method of the mineralized fly ash-based cementitious filling material resistant to mine water corrosion.

[0055] In the embodiment of the present application, a mineralized fly ash-based cementitious filling material resistant to mine water corrosion and a preparation method thereof are provided. The filling material is based on mineralized fly ash and the strength and corrosion resistance of the filling material are improved through the synergistic effect of multiple components in the composite activator and the anti-corrosion agent. The method includes: raw material premixing, activation and modification, and final mixing and packaging.

[0056] The following multiple examples and comparative examples in Table 1 show 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, and only differ 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 Example 2 with Example 1, it is found that the filling material obtained by adding nano-silica fume has enhanced performance in terms of compressive strength, sulfate corrosion coefficient and Cl- penetration depth;

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

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

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

[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, wherein the filling material is based on mineralized fly ash and the strength and corrosion resistance of the filling material are improved through the synergistic effect of multiple components in the composite activator and the anti-corrosion agent. The method comprises: premixing of raw materials, activation and modification, and final 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 are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application. The above are only preferred implementation methods 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, and these improvements and variations should also be regarded as the protection scope 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 ash and metakaolin according to the preset mass ratio; Excitation and modification: adding a composite exciter 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 exciter comprises sulphoaluminate, calcium hydroxide and polyaspartic acid-EDTA derivative; and the anti-corrosion agent comprises calcium nitrate, fluorinated polysilsesquioxane and halloysite nanotube-carboxymethyl cellulose composite; Final mixing and packaging: The second mixture obtained in the excitation and modification steps is stirred, and then sealed and packaged to obtain a filling material.

2. The method according to claim 1, characterized in that The preparation steps of the mineralized fly ash include: The fly ash is prepared into a slurry, and the slurry is subjected to a direct liquid phase mineralization reaction with CO2 gas to reduce the pH value of the slurry to 7.5; 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 then dried to obtain mineralized fly ash with a porous structure.

3. The method according to claim 2, 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.

4. 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.

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

1.

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

7. 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 anti-corrosion agent is 1:1:0.

1.

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

9. The method according to claim 1, characterized in that: The preparation steps of the halloysite nanotube-carboxymethyl cellulose composite include: (1) dispersing halloysite nanotubes in deionized water and subjecting the mixture to ultrasonic treatment for 30 minutes to form a dispersion having 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% 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; (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; (4) slowly dropping the dispersion into the carboxymethyl cellulose-maleamide 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; (5) The composite material is taken out, and washed repeatedly with deionized water; and dried at 60° C. for 24 hours to obtain a halloysite nanotube-carboxymethyl cellulose composite.

10. A mineralized fly ash-based cementitious filling material resistant to mine water corrosion, characterized in that: The material is prepared by the method for preparing the mineralized fly ash-based cementitious filling material resistant to mine water corrosion as described in any one of claims 1 to 9.

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