Composite gelling material using silicon-aluminum solid waste as raw material and preparation method thereof

Abstract

A composite cementitious material using silicoaluminous solid waste as raw material and a preparation method thereof belong to the technical field of solid waste resource utilization and composite cementitious materials. The composite cementitious material using silicoaluminous solid waste as raw material comprises the following raw materials in parts by weight: 55-35 parts of bauxite powder, 30-35 parts of slag, 15-30 parts of self-igniting coal gangue powder, 3-6 parts of activator, and a water-cement ratio of 0.3-0.34. The present invention can use low-activity bauxite powder to prepare a high-performance composite cementitious material, which not only expands the source of raw materials for the preparation of cementitious materials, but also can consume a large amount of industrial bulk solid waste, reducing environmental pollution. At the same time, it provides a feasible basic solution for the large-scale disposal of tailings rich in silicoaluminous components.

Description

Technical field:

[0001] The present invention belongs to the technical field of solid waste resource utilization and composite gelling materials, and in particular relates to a composite gelling material using silicon-aluminum solid waste as raw materials and a preparation method thereof. Background technology:

[0002] Alkali-activated cementitious materials have undergone years of development, and their basic properties and fundamental principles, such as the silica-alumina polymerization reaction, are now well understood. However, this understanding is based on common raw materials such as slag, fly ash, and metakaolin. Alkali-activated cementitious materials currently suffer from a limited number of cementitious materials and high costs. Furthermore, the SiO2 / Al2O3 molar ratio of the aluminosilicate raw material is a major factor influencing the microstructure and engineering properties of the cementitious binder system. However, most pozzolanic cementitious materials exhibit low or inferior bonding properties due to the weak reactivity caused by the high SiO2 / Al2O3 molar ratio of the raw material.

[0003] Although some progress has been made in the research of new cementitious materials in recent years, there are few reports on the preparation of filling cementitious materials using bauxite powder with high alumina.

[0004] Long-term research by several scholars has revealed that bauxite powder, a high-alumina rock powder, can be appropriately combined with volcanic ash to improve the performance of binder systems. However, in its natural state, due to its highly crystalline phases, including gibbsite, boehmite, and monohydrate, bauxite exhibits low solubility and activity in alkaline media. Therefore, research on how to efficiently increase the activity of bauxite powder could not only address the problem of large-scale tailings storage and disposal difficulties, but also significantly reduce the cost of backfill mining, truly achieving green mine construction and sustainable development in the mining industry. Summary of the invention:

[0005] The technical problems to be solved by the present invention are:

[0006] 1. One of the objectives of the present invention is to improve the shortcomings of low solubility and low reactivity of bauxite powder in alkaline media by grinding, while making full use of the coupling effect between solid waste materials as much as possible to achieve the improvement of the reactivity of bauxite powder and the mechanical properties of composite cementitious materials.

[0007] 2. The second purpose of the present invention is to utilize the synergistic effect, activity complementarity and particle grading optimization among bauxite powder, slag and natural coal gangue powder to provide a good aluminosilicate solid powder, and through the active stimulation of a composite activator, prepare an aluminum-rich aluminosilicate cementitious material with good gelling properties, good working performance, moderate strength, convenient construction and low environmental load.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A composite cementitious material made from silicoaluminous solid waste, composed of bauxite powder, slag powder, natural coal gangue, an activator, and water. The weight proportions of the components are as follows: 55-35 parts bauxite powder, 30-35 parts slag, 15-30 parts spontaneous combustion coal gangue powder, and 3-6 parts activator. The water-to-binder ratio (the mass ratio of water to the sum of all components) is 0.3-0.34.

[0010] Furthermore, the activator is compounded by sodium hydroxide and sodium silicate, wherein the sodium silicate adopts industrial grade instant type with a modulus of 2.0 to 2.3, and the sodium hydroxide is white particles with a purity of ≥96%.

[0011] Furthermore, the slag powder is of S105 grade, with a specific surface area of ​​not less than 2500m 2 / Kg.

[0012] Furthermore, the Al2O3 content of the bauxite powder is 50% to 70%, the SiO2 content is 15% to 35%, and the passing rate of the bauxite powder through a 0.3 mm square hole sieve is not less than 90%, and the specific surface area is not less than 3000 m 2 / Kg.

[0013] Furthermore, the spontaneous combustion gangue has a SiO2 content of 55% to 70%, an Al2O3 content of 15% to 25%, and a CaO content of 3% to 10%.

[0014] A method for preparing a composite gelling material using silicon-aluminum solid waste as raw materials comprises the following steps:

[0015] (1) Preliminary material processing:

[0016] The bauxite powder is placed in a dryer at a drying temperature of 103° C. to 105° C. for 12 to 24 hours, and the dried bauxite powder is then placed in a planetary ball mill for 15 to 20 minutes, and then passed through a 0.15 mm square hole sieve. The bauxite powder that does not pass through the 0.15 mm square hole sieve is mechanically crushed and then ball milled, and sieved again. The above steps are repeated until all the bauxite powder is sieved, and the maximum particle size of the final material is less than 0.15 mm, and the particle size distribution of 1-30 μm is greater than 98%;

[0017] The spontaneous combustion gangue is placed in a dryer at a drying temperature of 103° C. to 105° C. for 12 to 24 hours, and the dried spontaneous combustion gangue is then crushed in a jaw crusher and passed through a 0.35 mm square hole sieve. The crushed spontaneous combustion gangue powder is then placed in a planetary ball mill for 15 to 20 minutes and passed through a 0.15 mm square hole sieve. The spontaneous combustion gangue powder that does not pass through the 0.15 mm square hole sieve is further mechanically crushed and then ball milled, and sieved again. The above steps are repeated until all the spontaneous combustion gangue powder has passed the sieve, and the maximum particle size of the final material is less than 0.15 mm, and the particle size distribution of 1-30 μm is greater than 98%;

[0018] Preparation of activator: weigh and mix industrial-grade instant sodium silicate and sodium hydroxide in proportion, fully dissolve and mix them evenly, let them stand for 2 to 3 hours, and wait for the solution to cool to room temperature to prepare the activator.

[0019] Preparation of gelling material: weigh the raw materials according to the ratio, put them into a stirring pot, stir for 30 seconds to obtain a composite powder, pour the activator into the stirring pot, stir again for 210 seconds to 240 seconds to obtain a composite gelling material.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention promotes the hydration of slag powder by providing an alkaline environment through the activator. At the same time, the coupling effect between the aluminum-rich bauxite powder, the calcium-silicon-rich slag powder, and the silicon-rich natural coal gangue powder is utilized to make the composite system into a hydraulic cementitious material with a certain strength.

[0022] 2. The present invention uses a multi-power source activation method of mechanical grinding and chemical coupling activation, selects slag powder and low-activity natural coal gangue powder to achieve synergistic effects, and other means to improve the reactivity of bauxite powder under alkaline conditions. The calcium ions generated by the dissolution of slag powder promote the polymerization reaction of aluminum monomers generated by the depolymerization of bauxite powder and silicon monomers generated by the depolymerization of natural coal gangue powder, thereby achieving the effect of improving the dissolution and reactivity of bauxite powder, and further achieving the improvement of the strength of bauxite powder-based cementitious materials.

[0023] 3. After the introduction of calcium-rich slag powder, the Ca content in the liquid phase was increased. 2+The ion solubility changes the Ca / Si ratio of the system, providing calcium for the formation of hydrated calcium silicate and calcium aluminoferrite, increasing the early strength of the system and leading to a rapid decrease in the setting time, while also increasing the alkali concentration of the slurry. At the same time, the introduction of natural coal gangue powder rich in silicon phase replenishes the silicon element in the system, changes the Si / Al ratio of the system, and contributes to the formation of hydrated calcium silicate and the improvement of the polymerization degree of hydration products, thereby enhancing the early and late strength of the system. By matching slag and self-igniting coal gangue micropowder, the reaction process, product composition, microstructure and macroscopic performance activity of bauxite powder-based cementitious materials at each stage are improved, and a synergistic strengthening design theory and preparation method for multi-system cementitious materials suitable for bauxite powder matrix are proposed.

[0024] 4. This invention utilizes low-activity bauxite powder to produce a high-performance composite cementitious material. This not only expands the raw material sources for cementitious materials but also significantly reduces environmental pollution by consuming large quantities of solid waste. It also provides a feasible solution for the large-scale disposal of tailings rich in silica and aluminum components. Description of the drawings:

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the hydration product of the comparative example.

[0026] Figure 2 This is a scanning electron microscope (SEM) image of the hydration product of Example 1 of the present application.

[0027] Figure 3 This is the XRD diagram of the hydration product of Example 1 and the comparative example of this application.

[0028] Figure 4 It is the FTIR peak fitting diagram of the hydration product of the comparative example.

[0029] Figure 5 This is the FTIR peak fitting diagram of the hydration product of Example 1 of the present application. Specific implementation method:

[0030] In order to make the purpose, technical solutions and advantages of the invention clearer, the following description further describes the specific embodiments of the present invention:

[0031] An embodiment of the present invention provides a composite cementitious material using siliceous alumina solid waste as raw materials and a preparation method thereof. The composite cementitious material is compounded from bauxite powder, slag powder, natural coal gangue powder, an activator and water, and the weight proportions of each component are as follows: 55 to 35 parts of bauxite powder, 30 to 35 parts of slag, 15 to 30 parts of self-igniting coal gangue powder, 3 to 6 parts of activator, and a water-cement ratio of 0.3 to 0.34.

[0032] Example 1:

[0033] This embodiment provides a composite cementitious material using aluminosilicate solid waste as raw materials. The composite cementitious material includes the following raw materials by weight: 45 parts bauxite powder, 35 parts slag powder, 20 parts natural coal gangue powder, a water-binder ratio of 0.32, and 5 parts activator. The bauxite powder, slag powder, and natural coal gangue powder are all aluminosilicate solid waste materials.

[0034] In this embodiment: the Al2O3 content in the bauxite powder is 72%, the SiO2 content is 21%, and the passing rate of the bauxite powder through a 0.15 mm square hole sieve is not less than 85%; the Al2O3 content in the slag powder is 13%, the SiO2 content is 25%, and the CaO content is 50%; the Al2O3 content in the natural gangue powder is 21%, the SiO2 content is 64%, and the passing rate of the bauxite powder through a 0.15 mm square hole sieve is not less than 85%.

[0035] In this embodiment, the activator comprises the following raw materials in parts by weight: 11 parts of sodium hydroxide and 42 parts of sodium silicate, wherein the sodium silicate is an industrial grade instant type with a modulus of 2.3, and the sodium hydroxide is white granules with a purity of ≥96%.

[0036] The present embodiment provides a method for preparing a composite gelling material using silicon-aluminum solid waste as raw materials, comprising the following steps:

[0037] (1) Material drying: Place bauxite powder and self-igniting coal gangue in a dryer at a drying temperature of 103°C to 105°C for 12 to 24 hours.

[0038] (2) Material grinding: Place the bauxite powder in a dryer at a drying temperature of 103°C to 105°C for 12 to 24 hours, then place the dried bauxite powder in an XQM-4 vertical planetary ball mill for 15 to 20 minutes, and then pass through a 0.15 mm square hole sieve. The bauxite powder that does not pass through the 0.15 mm square hole sieve is further mechanically crushed and then ball milled, and sieved again. Repeat the above steps until all the bauxite powder is sieved, and the final material has a maximum particle size of less than 0.15 mm and a particle size distribution of 1 to 30 μm> 98%.

[0039] The spontaneous combustion gangue is placed in a dryer at a drying temperature of 103°C to 105°C for 12 to 24 hours. The dried spontaneous combustion gangue is then crushed in a jaw crusher and passed through a 0.35mm square hole sieve. The crushed spontaneous combustion gangue powder is then placed in an XQM-4 vertical planetary ball mill for ball milling for 15 to 20 minutes and passed through a 0.15mm square hole sieve. The spontaneous combustion gangue powder that does not pass through the 0.15mm square hole sieve is further mechanically crushed and then ball milled, and sieved again. The above steps are repeated until all the spontaneous combustion gangue powder is sieved, and the maximum particle size of the final material is less than 0.15mm, and the particle size distribution is 1 to 30μm>98%.

[0040] (3) Preparation of activator: Industrial-grade instant sodium silicate and sodium hydroxide are weighed and mixed according to a certain proportion, and the mixture is fully dissolved and mixed evenly. The mixture is allowed to stand for 2 to 3 hours, and the solution is cooled to room temperature to obtain the activator.

[0041] (4) Preparation of gelling material: Weigh each raw material according to the ratio, place it in a stirring pot, stir for 30 seconds to obtain a composite powder, pour the activator into the stirring pot, and stir again for 210 seconds to 240 seconds to prepare the gelling material.

[0042] (5) Curing of cementitious materials: The prepared cementitious materials were stirred and molded into test blocks of 40 mm × 40 mm × 40 mm. The test blocks were placed in a standard curing box for curing for 48 hours and then removed from the mold. After removal from the mold, the test blocks were placed in a curing box at 20 ± 1 °C for water curing.

[0043] Example 2:

[0044] This embodiment provides a composite cementitious material using silicon-aluminum solid waste as raw materials, including the following raw materials in parts by weight:

[0045] 35 parts of bauxite powder, 35 parts of slag powder, 30 parts of natural coal gangue powder, water-binder ratio 0.32, 5 parts of activator.

[0046] The preparation method of a composite gelling material using silicon-aluminum solid waste as raw materials in this embodiment is the same as the preparation method in Example 1.

[0047] The raw materials were weighed according to the ratio, placed in a stirring pot, and stirred for 30 seconds to obtain a composite powder. The activator was poured into the stirring pot and stirred again for 210 to 240 seconds. The cementitious material prepared in Example 1 was stirred and formed into a 40 mm × 40 mm × 40 mm test block. The test block was placed in a standard curing box for curing for 48 hours and then demolded. After demolding, the test block was placed in a curing box at 20±1°C for water curing.

[0048] Example 3:

[0049] This embodiment provides a composite cementitious material using silicon-aluminum solid waste as raw materials, including the following raw materials in parts by weight:

[0050] 55 parts of bauxite powder, 35 parts of slag powder, 10 parts of natural coal gangue powder, water-binder ratio 0.32, and 5 parts of activator.

[0051] The preparation method of a composite gelling material using silicon-aluminum solid waste as raw materials in this embodiment is the same as the preparation method in Example 1.

[0052] The raw materials were weighed according to the ratio, placed in a stirring pot, and stirred for 30 seconds to obtain a composite powder. The activator was poured into the stirring pot and stirred again for 210 to 240 seconds. The cementitious material prepared in Example 1 was stirred and formed into a 40 mm × 40 mm × 40 mm test block. The test block was placed in a standard curing box for curing for 48 hours and then demolded. After demolding, the test block was placed in a curing box at 20±1°C for water curing.

[0053] Reference Figure 1 and Figure 2 SEM analysis of the preferred Example 1 and the comparative example of the present invention revealed that Example 1 contained more agglomerated hydration products than the comparative example. The resulting hydration products formed agglomerates, encapsulating unhydrated particles, and contained numerous tiny, flake-like hydration products. Furthermore, flake-like hydration products, such as Ca(OH)2, were visible in the SEM image of Example 1. Although some porosity still existed within the cementitious material system, and the hydration products were not fully developed, the amount of hydration products produced was higher than in the comparative example, indicating a higher degree of hydration reaction than in the comparative example.

[0054] Analysis of hydration products and mechanisms:

[0055] Reference Figure 3 XRD phase analysis of the preferred embodiment 1 and the comparative example of the present invention revealed that the incorporation of silicon-rich spontaneous combustion gangue powder reduced the system's silicon-to-aluminum ratio and provided a large source of silicon phase material. The [SiO₄] produced by the rupture of silicon-oxygen bonds (-Si-O-) in the natural gangue powder under alkaline conditions and the [AlO₄] produced by the rupture of aluminum-oxygen bonds (-Al-O-) in the bauxite powder under alkaline conditions reacted, resulting in the formation of CASH in the hydration product and an increase in the hydration product content. Furthermore, it was observed that a large number of unreacted SiO₂ crystals in the natural gangue filled the pores of the hydration product in the form of particles, resulting in an improvement in the mechanical strength of embodiment 1 compared to the comparative example.

[0056] Reference Figure 4 and Figure 5 Through Fourier spectrum FTIR test analysis of the preferred embodiment 1 and the comparative example in the present invention, it was found that after the spontaneous combustion coal gangue rich in silicon phase was added, the hydration product was 800-1200cm in the infrared Fourier test. -1 The peak position and area of ​​the peaks are different. Compared with the comparative example, the addition of spontaneous combustion coal gangue in the implementation case 1 makes the SiQ 4 The peak area of ​​the structure increased by 17.01%, indicating that the addition of spontaneous combustion coal gangue makes it easier for the CSH gel in the system to polymerize into a three-dimensional network structure. Furthermore, a higher degree of polymerization of the amorphous CSH gel is more beneficial for improving the mechanical properties of the cementitious material. This further demonstrates the strength optimization effect of the ratio method proposed in this example.

[0057] Table 1 Composite cementitious material ratio

[0058]

[0059] Table 2 Properties of composite cementitious materials

[0060] Implementation Cases Liquidity 3D Strength 7d strength 28d strength Comparative Example 219mm 35.88MPa 40.04Mpa 50.83Mpa Implementation Case 1 195mm 47.74Mpa 54.55MPa 79.34Mpa Implementation Case 2 187mm 45.18Mpa 54.34Mpa 60.78Mpa Implementation Case 3 203mm 46.32Mpa 60.32Mpa 76.36Mpa

[0061] All raw materials listed in the present invention can realize the present invention, and the upper and lower limits and interval values ​​of each raw material can be realized, and the embodiments are not listed one by one here.

[0062] The above is an inspiration based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical idea of ​​this invention.

[0063] The technical scope of this invention is not limited to the contents of the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A composite cementitious material using siliceous alumina solid waste as raw materials, prepared by mixing bauxite powder, slag powder, natural coal gangue powder, an activator, and water. The weight proportions of the components are as follows: 55-35 parts of bauxite powder, 30-35 parts of slag, 15-30 parts of spontaneous combustion coal gangue powder, 3-6 parts of activator, and a water-binder ratio of 0.3-0.

34. The bauxite powder has an Al2O3 content of 50% to 70%, a SiO2 content of 15% to 35%, a 0.3 mm square hole sieve pass rate of not less than 90%, and a specific surface area of ​​not less than 3000 m 2 / Kg; The spontaneous combustion gangue has a SiO2 content of 55% to 70%, an Al2O3 content of 15% to 25%, and a CaO content of 3% to 10%, and a passing rate on a 0.15 mm square hole sieve of not less than 85%; The activator is compounded by sodium hydroxide and sodium silicate, wherein the sodium silicate adopts industrial grade instant type with a modulus of 2.0-2.3, and the sodium hydroxide is white particles with a purity of ≥96%.

2. A method for preparing a composite gelling material using silicon-aluminum solid waste as raw materials as claimed in claim 1, characterized in that: The following steps are involved: Material drying: Place bauxite powder and spontaneous combustion coal gangue in a dryer at a drying temperature of 103°C to 105°C for 12 to 24 hours; Grinding of bauxite powder: Grinding the bauxite powder obtained by drying in a planetary ball mill to obtain a powdery substance; Grinding of natural gangue: Grinding the spontaneous combustion gangue obtained by drying to obtain powdery material; Preparation of activator: weigh and mix industrial-grade instant sodium silicate and sodium hydroxide in proportion, fully dissolve and mix them evenly, let them stand for 2 to 3 hours, and wait for the solution to cool to room temperature to prepare the activator; Preparation of gelling material: weigh all raw materials according to the proportion, place them in a stirring pot, stir for 30 seconds to obtain composite powder, pour the activator into the stirring pot, stir again for 210 seconds to 240 seconds to prepare the gelling material; Curing of cementitious materials: The prepared cementitious materials were stirred and formed into test blocks of 40 mm × 40 mm × 40 mm. The test blocks were placed in a standard curing box for curing for 48 hours and then demolded. After demolding, the test blocks were placed in a curing box at 20 ± 1 ° C for water curing.

3. The method for preparing a composite gelling material using silicon-aluminum solid waste as raw materials according to claim 2, characterized in that The bauxite powder is ground in an XQM-4 vertical planetary ball mill. The ball-to-material ratio is ball-milled for 15 to 20 minutes, and then passed through a 0.15mm square hole sieve. The bauxite powder that does not pass through the 0.15mm square hole sieve is further mechanically crushed and then ball-milled, and sieved again. The above steps are repeated until all the bauxite powder has passed the sieve. The maximum particle size of the final material is less than 0.15mm, and the particle size distribution is 1-30μm>98%.

4. The method for preparing a composite gelling material using silicon-aluminum solid waste as raw materials according to claim 2, characterized in that Grinding treatment of natural coal gangue: Place the natural coal gangue gravel in a jaw crusher for crushing and pass it through a 0.35mm square hole sieve, and then place the self-igniting coal gangue powder obtained by the crushing treatment in a planetary ball mill for ball milling for 15 to 20 minutes, and pass it through a 0.15mm square hole sieve. The self-igniting coal gangue powder that does not pass through the 0.15mm square hole sieve is further mechanically crushed and then ball milled, and sieved again. Repeat the above steps until all the self-igniting coal gangue powder is sieved, and the maximum particle size of the final material is less than 0.15mm, and the particle size distribution is 1-30μm>98%.

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