Coal gangue brick and preparation method thereof

Abstract

The invention provides a coal gangue brick. The coal gangue brick comprises a gel material, aggregate, an additive, silicon dioxide nanoparticles and water, the admixture is powder, the mass of the admixture is 0.09-0.17% of the sum of the mass of the gel material and the mass of the aggregate, the mass of the silicon dioxide nano-microspheres is 0.71-3.57% of the mass of the gel material, and the silicon dioxide nano-microspheres are prepared by the following preparation method: dispersing prepared silicon dioxide gel in water at 90-100 DEG C; the heat preservation energy efficiency of the vacuum heat preservation device is grade I or grade II, and the heat preservation effect of the heat preservation energy efficiency is gradually reduced from the grade I to the grade II; and filtering, washing, drying in vacuum, and sintering to obtain the silicon dioxide nano-microsphere. According to the coal gangue brick provided by the invention, the particle size uniformity of the coal gangue brick is improved by optimizing the preparation process of the silicon dioxide nanoparticles, so that the mechanical property of the modified coal gangue brick is improved. The invention also provides a preparation method of the coal gangue brick.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, in particular to a gangue brick and a preparation method thereof. Background Art

[0002] Cement is the most widely used cementitious material in the construction industry, having been used for two centuries. Its widespread use has fueled the rapid development of the construction industry, but this growth has also brought numerous challenges. Firstly, the production of Portland cement consumes enormous amounts of energy and resources, and emits large amounts of greenhouse gases (CO2) and other harmful gases into the atmosphere, causing environmental pollution. Reducing the amount of Portland cement clinker used can reduce energy consumption, lower carbon emissions, and increase economic and environmental benefits. However, while reducing the amount of Portland cement clinker, it is also necessary to ensure that the essential properties of cement are not affected. Therefore, the addition of various mineral admixtures to ordinary cement has become a common method for improving the properties of cementitious materials.

[0003] Studies have found that adding nano-silica to cementitious materials can improve the mechanical properties, durability, and microstructure of cement-based materials. The mechanism of action is:

[0004] Silica nanospheres (SiO2) incorporated into cement-based composites exhibit strong pozzolanic activity and a filling effect. They can undergo a secondary hydration reaction with the cement hydration product Ca(OH)2 in the interfacial transition zone (ITZ) to form C–S–H. This effectively improves the pore structure and density of the ITZ, thereby enhancing the macroscopic properties of cement-based materials. This is manifested in the following ways: the incorporation of nano-SiO2 enhances the compressive strength of the cement matrix, primarily due to the filling effect of its nanoparticles, which improves the microscopic pore structure within the cement paste; nano-SiO2 can also densify the internal pore structure of the cement matrix, significantly improving its impermeability. Furthermore, the surface tension and agglomeration effect of NS accelerate the cement hydration process within the cement matrix through a nucleation effect.

[0005] The preparation process of nanosilica affects its particle size uniformity, which in turn affects the performance of nanosilica and cement gel materials. The present invention aims to provide a nanosilica-modified coal gangue brick. By optimizing the preparation process of silica nanospheres, the particle size uniformity is improved, thereby enhancing the mechanical properties of the coal gangue brick. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a coal gangue brick, by optimizing the preparation process of silicon dioxide nanoparticles, improving the uniformity of their particle size, and thus improving the mechanical properties of the coal gangue brick.

[0007] The technical solution of the present invention is:

[0008] A coal gangue brick comprises a gel material, aggregate, an admixture, silicon dioxide nano-microspheres and water;

[0009] The gel material includes cement, and the aggregate includes coal gangue and oil well soil;

[0010] The admixture is a powder, and its mass is 0.09-0.17% of the sum of the mass of the gel material and the aggregate. Specifically, the mass of the admixture can be 0.09%, 0.1%, 0.12%, 0.14%, 0.15% or 0.17% of the sum of the mass of the gel material and the aggregate, or other values within this range.

[0011] The mass of the silica nanoparticles is 0.71-3.57% of the mass of the gel material. The silica nanoparticles are prepared by the following preparation method:

[0012] Step S1, weighing appropriate amounts of deionized water and anhydrous ethanol, mixing them with appropriate amounts of aqueous ammonia, and mixing them under ultrasonic conditions;

[0013] Step S2, heating the mixed solution to 35-45° C., adding an appropriate amount of a mixed solution of tetraethyl orthosilicate and anhydrous ethanol, and stirring to react for 3-5 hours;

[0014] Step S3, washing, filtering, and vacuum drying the product of step S2 to obtain silica gel;

[0015] Step S4, dispersing the silica gel from step S3 in water at 90-100° C., and then placing the silica gel in a vacuum insulation device and letting it stand for 6-18 hours, wherein the insulation energy efficiency of the vacuum insulation device is level I or level II, wherein the insulation effect gradually decreases from level I to level II;

[0016] Step S5: filtering, washing, vacuum drying, and then sintering to prepare silica nanoparticles.

[0017] Furthermore, in step S4, the vacuum insulation device includes a main body having a feed port and a sealing cover sealed to the feed port, the main body includes an outer shell, an inner liner, a vacuum insulation layer formed between the outer shell and the inner liner, and an insulation coating coated on the inner wall of the inner liner, and the outer shell and the inner liner are connected near the feed port.

[0018] Furthermore, the admixture is a polycarboxylic acid water reducer or a melamine resin water reducer.

[0019] Furthermore, the gel material, aggregate, admixture, silica nanospheres and water are composed of the following components in parts by weight:

[0020] 120-160 parts of cement, 200-260 parts of coal gangue, 500-560 parts of oil well soil, 0.8-1.6 parts of admixture, 1-5 parts of silica nanospheres, and 90-110 parts of water.

[0021] Specifically, the weight proportion of cement can be 120 parts, 130 parts, 140 parts, 150 parts or 160 parts, or other values within this range; the weight proportion of coal gangue can be 200 parts, 220 parts, 240 parts, 250 parts or 260 parts, or other values within this range; the weight proportion of oil well soil can be 500 parts, 510 parts, 520 parts, 530 parts, 540 parts, 550 parts or 560 parts, or other values within this range; the weight proportion of admixture can be 0.8 parts, 1.0 parts, 1.2 parts, 1.4 parts, 1.5 parts or 1.6 parts, or other values within this range; the weight proportion of silica nanospheres can be 1 part, 2 parts, 3 parts, 4 parts or 5 parts, or other values within this range; the weight proportion of water can be 90 parts, 100 parts or 110 parts, or other values within this range.

[0022] The present invention also provides a method for preparing gangue bricks, comprising the following steps:

[0023] adding an admixture to the gel material;

[0024] The gel material is evenly mixed with other raw materials to obtain nano-silicon dioxide modified coal gangue bricks.

[0025] Compared with the prior art, the gangue bricks provided by the present invention have the following beneficial effects:

[0026] The present invention provides a gangue brick modified with silica nanospheres, prepared using a unique process. The silica nanospheres are prepared by placing silica gel in a vacuum insulation device for thermal insulation. This thermal insulation mechanism facilitates the production of crystals with a complete crystalline form and uniform particle size. Because the silica nanospheres have more uniform crystals, their addition to gangue bricks can significantly improve the mechanical properties of the bricks. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 Schematic diagram of the structure of the vacuum insulation device of the present invention;

[0029] Figure 2 The SEM images of the silica nanospheres prepared at different holding times in the present invention are shown;

[0030] Figure 3 These are SEM images of silicon dioxide nanospheres prepared using vacuum insulation devices with different energy efficiencies in the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention and to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific implementation methods of the present invention are further described below.

[0032] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] Example 1

[0034] A method for preparing silicon dioxide nanoparticles comprises the following steps:

[0035] Step S1, weighing appropriate amounts of deionized water and anhydrous ethanol, mixing them with appropriate amounts of aqueous ammonia, and mixing them under ultrasonic conditions;

[0036] Step S2, heating the mixed solution to 35-45° C., adding an appropriate amount of a mixed solution of tetraethyl orthosilicate and anhydrous ethanol, and stirring to react for 3-5 hours;

[0037] The heating temperature of the mixed solution can be 35°C, 40°C or 45°C, or other values within the range; the reaction time can be 3h, 4h or 5h, or other values within the range;

[0038] Step S3, washing, filtering, and vacuum drying the product of step S2 to obtain silica gel;

[0039] The vacuum drying temperature is 55-65° C., such as 55° C., 60° C. or 65° C., or other temperature values within this range.

[0040] Step S4, dispersing the silica gel from step S3 in water at 90-100° C., and then placing the silica gel in a vacuum insulation device and letting it stand for 6-18 hours, wherein the insulation energy efficiency of the vacuum insulation device is level I or level II, wherein the insulation effect gradually decreases from level I to level II;

[0041] The temperature of the dispersion may be 90°C, 95°C or 100°C, or other temperature values within this range, and the holding time may be 6h, 12h or 18h, or other values within this range;

[0042] The structure of the vacuum insulation device is as follows Figure 1 As shown, the vacuum insulation device includes a main body 1 with a feed port 11, and a sealing cover 2 sealed with the feed port 11. The main body 1 includes an outer shell 12, an inner liner 13, a vacuum insulation layer 14 formed between the outer shell 12 and the inner liner 13, and a thermal insulation coating 15 coated on the inner wall of the inner liner 13. The outer shell 12 and the inner liner 13 are connected near the feed port. After the material is injected from the feed port, the sealing cover is covered for thermal insulation treatment. Among them, the outer shell and the inner liner are made of stainless steel material, and the thermal insulation coating is a copper-plated layer or a silver-plated layer. The structure of the vacuum insulation device in the present invention is similar to that of a vacuum insulation cup. The vacuum insulation layer 14 is in a vacuum state, and the energy efficiency level of the vacuum insulation device is regulated by adjusting the vacuum degree in the vacuum insulation layer 14. The insulation principle of the vacuum insulation device in the present invention is: by evacuating the vacuum insulation layer, no heat is transferred in a vacuum state, thereby isolating heat transfer; by coating the inner wall of the inner liner with an insulation coating to form a heat-locking network, heat loss caused by thermal radiation is reduced; through the double-layer sealing structure of the inner liner and the outer shell, convection between the heat in the device and the outside air can be avoided, thereby reducing heat convection.

[0043] The energy efficiency level of the vacuum insulation device refers to the stainless steel vacuum insulation container GBT40355-2021. The insulation effect of the insulation device deteriorates from level I to level V. Therefore, the insulation effect of the insulation device with an insulation energy efficiency of level I is the best.

[0044] Step S5, filtering, washing, vacuum drying, and then sintering to prepare silica nanoparticles;

[0045] The vacuum drying temperature is 60-68°C, specifically 60°C, 65°C or 68°C, or other temperature values within this range; the sintering temperature is 900-1000°C, specifically 900°C, 950°C or 1000°C, or other temperature values within this range.

[0046] In the present invention, tetraethyl orthosilicate first undergoes a hydrolysis reaction, and the alkoxy group (-OR) in the tetraethyl orthosilicate molecule is replaced by a hydroxyl group (-OH), and the reaction formula is as follows:

[0047]

[0048] The silicic acid (Si(OH)4) generated by the hydrolysis reaction or the silicic acid and tetraethyl orthosilicate undergoes a condensation reaction to form Si-O-Si bonds, thereby generating silicon dioxide oligomers. The reaction formula is as follows:

[0049]

[0050] As the reaction proceeds, these oligomers will further polymerize to form a skeleton structure with long chains extending into space, and finally form silica gel. The obtained gel is dried to remove the moisture therein. The dried gel is heat-treated at high temperature to further remove the organic matter and residual moisture therein, and promote the crystallization and densification of the silica particles, and finally obtain nano-scale or micron-scale silica powder. The reaction mechanism of preparing silica by tetraethyl orthosilicate sol-gel method is a complex process, involving multiple steps such as hydrolysis reaction, polycondensation reaction and sol-gel transformation. The present invention optimizes the heat treatment mechanism and controls the temperature and time of insulation to regulate the morphology, structure and properties of silica.

[0051] Example 2

[0052] The preparation method of the silica nanospheres of the present invention is described in detail below through specific examples to obtain the optimal process parameters.

[0053] Weigh a certain amount of deionized water and anhydrous ethanol, mix them with a certain amount of ammonia water, and use an ultrasonic cleaner to ultrasonically mix for 15 minutes;

[0054] The mixture was placed in a three-necked round-bottom flask equipped with a stirrer, a condenser, and a constant-pressure dropping funnel. After the reaction temperature reached 40°C, a certain amount of a mixture of tetraethyl orthosilicate (TEOS) and anhydrous ethanol was added and stirred for 4 hours.

[0055] The product was washed with anhydrous ethanol, filtered, and dried under vacuum at 60°C for 12 h to obtain silica gel;

[0056] The above operation was repeated four times, and the silica gel was divided into 6 parts, dispersed in 95°C water, and placed in a vacuum insulation device with energy efficiency I to V at room temperature for 6 hours, 12 hours, 18 hours, and 24 hours respectively;

[0057] After standing, the precipitate was collected by filtration, washed by suction, and then dried at 65°C under vacuum conditions for 24 hours, then dried at 105°C for 2 hours, and finally sintered and cured at 950°C for 10 minutes to prepare silica nanospheres.

[0058] The prepared silica nanospheres were analyzed by SEM test, and the results are as follows: Figure 2 and Figure 3 As shown, Figure 2 SEM images of silica nanospheres in insulation devices with insulation energy efficiency levels of I to V under different insulation time conditions. Figure 2 A represents the SEM image of silica nanospheres in the insulation device with energy efficiency levels of I to V at room temperature corresponding to a 6-hour insulation time. Figure 2 B represents the SEM image of silica nanospheres in the insulation device with energy efficiency levels of I to V at room temperature corresponding to a 12-hour insulation time. Figure 2 C represents the SEM image of silica nanospheres in the insulation device with energy efficiency levels of I to V at room temperature corresponding to an 18-hour insulation time. Figure 2 D represents the SEM images of silica nanospheres in the insulation devices with energy efficiency levels I to V at room temperature corresponding to a 24-hour insulation time; Figure 3 The SEM images of silica nanoparticles obtained by heat preservation for different time periods in heat preservation devices with different energy efficiency levels are shown in FIG. Figure 3 A represents the SEM images of silica nanoparticles obtained after different insulation times in an insulation device with energy efficiency level I. Figure 3 B represents the SEM images of silica nanoparticles obtained after different insulation times in an insulation device with energy efficiency level II. Figure 3 C represents the SEM images of silica nanospheres obtained after different insulation times in an insulation device with energy efficiency level III. Figure 3 D represents the SEM images of silica nanospheres obtained after different insulation times in an insulation device with energy efficiency level IV. Figure 3 E represents the SEM images of silica nanospheres obtained after different insulation times in an insulation device with energy efficiency level V.

[0059] The insulation effect gradually deteriorates from level I to level V, and as the insulation efficiency level deteriorates, the stage of gentle temperature drop in the insulation device shifts later. Figure 2 and Figure 3 It can be seen that when the temperature changes slowly (the temperature drops less per unit time), it is more conducive to obtaining crystals with complete crystal form and uniform particle size. This shows that the better the thermal insulation effect, the more uniform the silica nanospheres.

[0060] The particle sizes of silica nanoparticles obtained by heating for different times in vacuum insulation devices with different insulation efficiencies are shown in Table 1:

[0061] Table 1: Particle size test results of silica nanospheres

[0062]

[0063]

[0064] Combine Figure 2 and Figure 3 As shown in Table 1, when the thermal insulation energy efficiency is level I and the thermal insulation time is 12h, the grains of silica nanospheres are more uniform and their performance is better.

[0065] Examples 3-9

[0066] The insulation time of the vacuum insulation device in Example 2 was 12 hours, and the silica nanospheres prepared with different insulation energy efficiencies were applied to coal gangue bricks to obtain nano-silica-modified coal gangue bricks.

[0067] Nano-silica modified coal gangue bricks include gel material, aggregate, polycarboxylic acid water reducer (powder), silica nano-microspheres and water.

[0068] Nano-silica microspheres prepared with different thermal insulation efficiencies were added to form Examples 3-9.

[0069] The proportions of the ingredients in Examples 3-9 are shown in Table 2:

[0070] Table 2: Ingredient ratios of Examples 3-9 Unit: kg / t

[0071]

[0072] The mechanical properties of the gangue bricks of Examples 3-9 are shown in Table 3:

[0073] Table 3: Mechanical properties test results of coal gangue bricks of Examples 3-9

[0074]

[0075]

[0076] As can be seen in Table 3, the compressive strength of gangue bricks varies significantly with the change in microsphere insulation efficiency. The highest compressive strength is achieved when microspheres are prepared with insulation efficiency level I. This is because the silica nanospheres used in Examples 4, 6, 7, 8, and 9 are less uniform in particle size than those used in Example 5.

[0077] Examples 10-14

[0078] The insulation energy efficiency of the vacuum insulation device in Example 2 is set to level I, and the insulation time is 12 hours. The prepared silica nanospheres are applied to coal gangue bricks to obtain coal gangue bricks modified with different nano-silica addition amounts.

[0079] Nano-silica modified coal gangue bricks include gel material, aggregate, polycarboxylate water reducer (powder), silica nano-microspheres and water.

[0080] The mass of silica nanospheres was added at 0.71%, 1.42%, 2.14%, 2.86%, and 3.57% of the mass of the gel material, respectively, to obtain coal gangue bricks with different proportions, forming Examples 10-14. The proportions of the components of Examples 10-14 are shown in Table 4:

[0081] Table 4: Composition ratio of Examples 10-14 Unit: kg / t

[0082]

[0083] The mechanical properties of the gangue bricks of Examples 10-14 are shown in Table 5:

[0084] Table 5: Mechanical properties test results of coal gangue bricks of Examples 10-14

[0085]

[0086] As can be seen in Table 5, the compressive strength of the gangue bricks first increases and then decreases with increasing silica nanosphere addition levels. The highest compressive strength is achieved when the silica nanosphere addition level is 3 kg / t, or 2.14% of the binder mass. This is because an appropriate amount of microspheres can optimize the interface transition zone between the cement matrix and aggregate, but an excessive amount can weaken the interface, forming weak areas and reducing overall strength.

[0087] Examples 15-19

[0088] The insulation energy efficiency of the vacuum insulation device in Example 2 is set to level I, and the insulation time is 12 hours. The prepared silica nanoparticles are applied to coal gangue bricks to obtain nano-silica-modified coal gangue bricks.

[0089] Nano-silica modified coal gangue bricks include gel material, aggregate, melamine resin water reducer (powder), silica nano-microspheres and water.

[0090] The mass of silica nanospheres was added at 0.71%, 1.42%, 2.14%, 2.86%, and 3.57% of the mass of the gel material, respectively, to obtain coal gangue bricks with different proportions, forming Examples 15-19. The proportions of the components of Examples 15-19 are shown in Table 6:

[0091] Table 6: Ingredient ratios of Examples 15-19 Unit: kg / t

[0092]

[0093]

[0094]

[0095] The mechanical properties of the gangue bricks of Examples 15-19 are shown in Table 7:

[0096] Table 7: Mechanical properties test results of coal gangue bricks of Examples 15-19

[0097]

[0098] As shown in Table 7, the compressive strength of gangue bricks increases with increasing silica nanosphere addition, then decreases. The highest compressive strength is achieved when the silica nanosphere addition level is 3 kg / t, or 2.14% of the binder mass. This is because an appropriate amount of microspheres can optimize the interface transition zone between the cement matrix and aggregate, but an excessive amount can weaken the interfacial bond, forming weak areas and reducing overall strength. Furthermore, as shown in Table 5, when using melamine resin, polycarboxylate water reducers are more effective in improving the strength of gangue bricks at the same mix ratio. This is because polycarboxylate water reducers are more sensitive and have a better water-reducing effect. They can effectively reduce the water-cement ratio of gangue bricks, reducing the amount of water aggregated within the gangue, thereby enhancing compressive strength.

[0099] Comparative Examples 1-5

[0100] Silica fume is used to replace silica nanospheres in coal gangue bricks to obtain silica fume modified coal gangue bricks.

[0101] Silica fume modified coal gangue bricks include cementitious materials, aggregates, polycarboxylic acid water reducer (powder), silica fume and water.

[0102] Silica fume was added at 0.71%, 1.42%, 2.14%, 2.86% and 3.57% of the mass of the gel material respectively to obtain gangue bricks with different proportions, forming comparative examples 1-5. The proportions of the components of comparative examples 1-5 are shown in Table 8:

[0103] Table 8: Composition ratio of comparative examples 1-5 Unit: kg / t

[0104] Serial number cement coal gangue Oil well soil Polycarboxylate water reducer silica fume water Comparative Example 1 140 230 530 1.2 1 100 Comparative Example 2 140 230 530 1.2 2 100 Comparative Example 3 140 230 530 1.2 3 100 Comparative Example 4 140 230 530 1.2 4 100 Comparative Example 5 140 230 530 1.2 5 100

[0105] The mechanical properties of the gangue bricks of Comparative Examples 1-5 are shown in Table 9:

[0106] Table 9: Mechanical properties test results of coal gangue bricks of comparative examples 1-5

[0107]

[0108] Comparative Examples 6-10

[0109] Silica fume is used to replace silica nanospheres in coal gangue bricks to obtain silica fume modified coal gangue bricks.

[0110] Silica fume modified coal gangue bricks include cementitious materials, aggregates, melamine resin water reducer (powder), silica fume and water.

[0111] Silica fume was added at 0.71%, 1.42%, 2.14%, 2.86% and 3.57% of the mass of the gel material, respectively, to obtain gangue bricks with different proportions, forming comparative examples 6-10. The proportions of the components of comparative examples 6-10 are shown in Table 10:

[0112] Table 10: Composition ratio of comparative examples 6-10 Unit: kg / t

[0113] Serial number cement coal gangue Oil well soil Melamine resin water reducer silica fume water Comparative Example 6 140 230 530 1.2 1 100 Comparative Example 7 140 230 530 1.2 2 100 Comparative Example 8 140 230 530 1.2 3 100 Comparative Example 9 140 230 530 1.2 4 100 Comparative Example 10 140 230 530 1.2 5 100

[0114] The mechanical properties of the gangue bricks of Comparative Examples 6-10 are shown in Table 13:

[0115] Table 11: Mechanical properties test results of coal gangue bricks of comparative examples 6-10

[0116]

[0117] Tables 9 and 11 show that the compressive strength of gangue bricks formulated with silica fume is related to the silica fume dosage. The compressive strength of the gangue bricks reached its highest when the silica fume dosage was 4.0 kg. Further increasing the silica fume dosage resulted in a slight decrease in the compressive strength of the gangue bricks. This is because an appropriate amount of silica fume can fill mortar pores, improving density and strength. However, excessive silica fume can lead to uneven particle packing, creating new pores or weak areas, and reducing strength.

[0118] In summary, the nano-silica modified coal gangue bricks of the present invention have more uniform crystal grains of silica nano-microspheres, which can significantly improve the mechanical properties of the bricks when added to the bricks.

[0119] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. A coal gangue brick, characterized in that: It includes gel material, aggregate, admixture, silica nanoparticles and water; The gel material includes cement, and the aggregate includes coal gangue and oil well soil; The admixture is a powder, and its mass is 0.09-0.17% of the sum of the mass of the gel material and the aggregate; The mass of the silica nanoparticles is 0.71-3.57% of the mass of the gel material, and the silica nanoparticles are prepared by the following preparation method: Step S1, weighing appropriate amounts of deionized water and anhydrous ethanol, mixing them with appropriate amounts of aqueous ammonia, and mixing them under ultrasonic conditions; Step S2, heating the mixed solution to 35-45° C., adding an appropriate amount of a mixed solution of tetraethyl orthosilicate and anhydrous ethanol, and stirring to react for 3-5 hours; Step S3, washing, filtering, and vacuum drying the product of step S2 to obtain silica gel; Step S4, dispersing the silica gel from step S3 in water at 90-100° C., and then placing the silica gel in a vacuum insulation device and letting it stand for 6-18 hours, wherein the insulation energy efficiency of the vacuum insulation device is level I or level II, wherein the insulation effect gradually decreases from level I to level II; Step S5: filtering, washing, vacuum drying, and then sintering to prepare silica nanoparticles.

2. The gangue brick according to claim 1, characterized in that: In step S4, the vacuum insulation device includes a main body with a feed port and a sealing cover sealed to the feed port, the main body includes an outer shell, an inner liner, a vacuum insulation layer formed between the outer shell and the inner liner, and an insulation coating coated on the inner wall of the inner liner, and the outer shell and the inner liner are connected near the feed port.

3. The gangue brick according to claim 1, characterized in that: The admixture is a polycarboxylic acid water reducer or a melamine resin water reducer.

4. The gangue brick according to claim 1, characterized in that: The gel material, aggregate, admixture, silicon dioxide nanospheres and water are composed of the following components in parts by weight: 120-160 parts of cement, 200-260 parts of coal gangue, 500-560 parts of oil well soil, 0.8-1.6 parts of admixture, 1-5 parts of silica nanospheres, and 90-110 parts of water.

5. A method for preparing a gangue brick according to claim 1, characterized in that: The steps include: adding an admixture to the gel material; The gel material is evenly mixed with other raw materials to obtain nano-silicon dioxide modified coal gangue bricks.

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