Coal gangue-based composite spraying material and preparation method thereof

Abstract

The invention discloses a coal gangue-based composite spraying material and a preparation method thereof. The preparation method comprises the following steps: preparing modified coal gangue fine aggregate; preparing to obtain a cementing material; and stirring the modified coal gangue fine aggregate, the cementing material and water to obtain the coal gangue-based composite spraying material. The high-performance coal gangue-based composite spraying material is prepared by innovatively utilizing the combination of the modified coal gangue fine aggregate and the cementing material in a specific ratio. According to the invention, the problem of environmental pollution caused by using coal gangue as solid waste is effectively solved, and the compressive strength, wear resistance and luminescence property of a final product are also remarkably improved.

Description

Technical Field

[0001] This application belongs to the technical field of spray material preparation, and specifically relates to a coal gangue-based composite spray material and its preparation method. Background Art

[0002] In current industrial practices, coal gangue, as the main solid waste in the coal mining process, its large accumulation not only occupies valuable land resources but may also cause serious environmental pollution. Although there have been attempts to apply coal gangue to building materials, most of these applications have not fully utilized its potential value, especially in terms of enhancing material functionality and added value, and there are obvious deficiencies. Especially in spray reinforcement, the demand for high-performance spray materials is increasing day by day, and traditional spray materials often face problems such as high cost, insufficient environmental protection performance, and single effect. Summary of the Invention

[0003] Aiming at the deficiencies in the prior art, the main purpose of this application is to provide a coal gangue-based composite spray material and its preparation method. Based on coal gangue, this application prepares high-performance spray materials through chemical modification and composite technology, which can not only effectively solve the environmental pollution problem of coal gangue but also provide an economical, efficient, and environmentally friendly new material solution.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] A coal gangue-based composite spray material, the spray material includes: modified coal gangue fine aggregate and a gelling material, wherein the mortar ratio of the gelling material to the modified coal gangue fine aggregate is 0.4 - 0.6:1.

[0006] Optionally, the gelling material includes: cement: 400 - 700 parts; silica fume: 50 - 100 parts; lithium slag powder: 10 - 40 parts; bentonite: 1 - 5 parts; fluorescent powder: 1 - 20 parts; glass microsphere reflective powder: 1 - 10 parts; water reducing agent: 1 - 3 parts.

[0007] This application also provides a preparation method for a coal gangue-based composite spray material, the preparation method includes: preparing a modified coal gangue fine aggregate; preparing a gelling material; stirring the modified coal gangue fine aggregate, the gelling material, and water to obtain a coal gangue-based composite spray material.

[0008] Optionally, the preparation of the modified coal gangue fine aggregate includes: crushing the coal gangue selected from coal; soaking the crushed coal gangue in an alkaline solution and drying it; soaking the dried coal gangue in a sodium sulfate solution again and drying it; spraying a calcium chloride solution on the surface of the coal gangue after drying it again, and stacking and aging it to obtain a modified coal gangue fine aggregate.

[0009] Optionally, the coal gangue selected from coal is crushed by low-temperature freezing combined with ultrasonic vibration.

[0010] Optionally, the alkaline solution includes any one of the following: saturated lime water, calcium hydroxide, and sodium hydroxide solution.

[0011] Optionally, the preparation of the obtained cementitious material includes: surface pretreatment of phosphor powder and glass microspheres; plasma activation of lithium slag powder: mixing cement, silica fume, activated lithium slag powder, and bentonite under microwave action to obtain a mixture; adding the phosphor powder and glass microspheres that have completed nano-coating to the mixture in steps, and performing ultrasonic dispersion synchronously after each addition, thus obtaining the cementitious material.

[0012] Optionally, the stirring of the modified coal gangue fine aggregate, the cementitious material, and water to obtain the coal gangue-based composite spraying material includes: stirring and mixing the modified coal gangue fine aggregate and the cementitious material to obtain a mixture; continuing to perform vacuum stirring on the mixture; while performing vacuum stirring, gradually adding a predetermined amount of water and maintaining the stirring state, and performing ultrasonic dispersion during the water addition process to obtain the coal gangue-based composite spraying material.

[0013] Optionally, the added water is magnetized water.

[0014] Optionally, the water-cement ratio of the mixture and water is 0.4 - 0.6.

[0015] This application can bring the following beneficial effects:

[0016] This application innovatively combines the modified coal gangue fine aggregate with a cementitious material in a specific ratio to prepare a high-performance coal gangue-based composite spraying material. This application not only effectively solves the environmental pollution problem caused by coal gangue as a solid waste, but also significantly improves the compressive strength, wear resistance, and luminescence performance of the final product, while reducing costs and enhancing environmental protection, and is applicable to a variety of application scenarios that require high visibility and durability. Description of the Drawings

[0017] Figure 1 is a schematic flow chart of a method for preparing a coal gangue-based composite spraying material provided by an embodiment of this application;

[0018] Figure 2 is a schematic diagram of an existing ordinary spraying material under light conditions;

[0019] Figure 3 is a schematic diagram of an existing ordinary spraying material under dark conditions;

[0020] Figure 4It is a schematic diagram of the spraying material obtained by the preparation of this application under light conditions;

[0021] Figure 5 It is a schematic diagram of the spraying material obtained by the preparation of this application under dark conditions. Detailed implementation manners

[0022] Next, the technical solutions in the embodiments of this application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0024] In this application, unless otherwise clearly defined and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0025] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of this application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by this application.

[0026] In an exemplary embodiment, the present application provides a coal gangue-based composite spraying material, characterized in that the spraying material comprises: modified coal gangue fine aggregate and a cementitious material, wherein the mortar ratio of the modified coal gangue fine aggregate to the cementitious material is 0.4 to 0.6, and further preferably, the mortar ratio of the modified coal gangue fine aggregate to the cementitious material is 0.5.

[0027] In this embodiment, after inspection, when the mortar ratio is within the range of 0.4 to 0.6, the mixture of the modified coal gangue fine aggregate and the cementitious material has good fluidity and plasticity. If the mortar ratio is too low (i.e., too much cementitious material), the mixture will be too viscous and not easy to lay and level; conversely, if the mortar ratio is too high (i.e., too little cementitious material), the mixture will have too large fluidity and be difficult to maintain its shape. In addition, research shows that within the range of 0.4 to 0.6, the finally prepared spraying material can obtain better compressive strength and wear resistance because an appropriate amount of cementitious material can fully wrap the coal gangue fine aggregate, reduce the porosity, enhance the interfacial bonding force, and thus improve the overall strength. In addition, the reason for choosing 0.5 as the preferred mortar ratio is that at this ratio, the most ideal interaction relationship can be formed between the modified coal gangue fine aggregate and the cementitious material, which can not only effectively fill the voids but also maintain appropriate density and fluidity.

[0028] Next, the present application will illustrate the above-mentioned mortar ratio through specific experimental data, as shown in Table 1 specifically:

[0029] Table 1

[0030]

[0031] In Table 1, at a mortar ratio of 0.5, the cementitious material can fully wrap the coal gangue fine aggregate, enabling the compressive strength of the spraying material to reach 35 to 38, which is better than the mortar ratios of 0.4 and 0.6; at a mortar ratio of 0.5, the wear resistance of the spraying material reaches 25 to 30, which is better than the mortar ratios of 0.4 and 0.6; the fluidity of the 0.4 mortar ratio is the best, but it is easy to cause the spraying material to be too thin, and the 0.6 mortar ratio has poor fluidity of the spraying material due to too much cementitious material, while the 0.5 mortar ratio can balance the fluidity and workability; at a mortar ratio of 0.5, the porosity of the spraying material is the lowest and the density is the highest, both of which are better than the mortar ratios of 0.4 and 0.6.

[0032] In another exemplary embodiment, the cementitious material comprises: cement: 400 to 700 parts; silica fume: 50 to 100 parts; lithium slag powder: 10 to 40 parts; bentonite: 1 to 5 parts; fluorescent powder: 1 to 20 parts;

[0033] Glass microsphere reflective powder: 1 - 10 parts; Water reducing agent: 1 - 3 parts. Preferably, the cementitious material includes: Cement: 600 parts; Silica fume: 70 parts; Lithium slag powder: 30 parts; Bentonite: 2 parts; Phosphor powder: 2 parts; Glass microsphere reflective powder: 5 parts; Water reducing agent: 2 parts.

[0034] In this embodiment, the amount of cement directly affects the strength and durability of the material. The range of 400 to 700 parts provides sufficient flexibility to adapt to different application scenarios. Among them, 600 parts as a preferred value can ensure sufficient strength while avoiding cost increase and unnecessary shrinkage cracks caused by excessive use. 50 to 100 parts of silica fume can fill the tiny pores between cement particles and improve the overall performance of the material. Among them, 70 parts of the preferred value is sufficient to exert its strengthening effect, and excessive use is avoided to prevent cost increase and possible increase in operation difficulty. 10 to 40 parts of lithium slag powder helps to improve the durability of the material and enhance the late strength development. Among them, 30 parts of the dosage can maximize the advantages of lithium slag powder without affecting other properties. 1 to 5 parts of bentonite can effectively improve the workability of the material and prevent segregation. Among them, 2 parts of the dosage can meet the construction requirements without overly affecting fluidity or increasing unnecessary costs. Adding 2 parts of phosphor powder can provide sufficient fluorescence effect without significantly affecting the overall performance of the material. 1 to 10 parts of glass microsphere reflective powder can significantly improve the luminescence coefficient of the material. Among them, 5 parts of the preferred value can ensure the luminescence effect of the phosphor powder while maintaining other key properties of the material, such as mechanical strength and construction convenience. 1 to 3 parts of water reducing agent can optimize the fluidity and pumpability of the mixture. Among them, 2 parts of the dosage is sufficient to achieve the expected effect while avoiding side effects that may be caused by excessive use, such as bleeding or strength reduction.

[0035] Next, the application will illustrate the dosage of each component above through experimental data, as shown in Table 2 specifically:

[0036] Table 2

[0037]

[0038]

[0039] As can be seen from Table 2, the preferred values of each component can significantly improve the comprehensive performance of the sprayed material.

[0040] Figure 1 This is a coal gangue-based composite spraying material and its preparation method provided by an exemplary embodiment of the application. As Figure 1 described, the preparation method includes the following steps:

[0041] S100: Prepare and obtain modified coal gangue fine aggregate;

[0042] S200: Prepare and obtain a gelling material;

[0043] S300: Stir the modified fine coal gangue aggregate, the gelling material, and water to obtain a coal gangue-based composite spraying material.

[0044] In another exemplary embodiment, in step S100, the preparation of the modified fine coal gangue aggregate includes the following steps:

[0045] S101: Crush the coal gangue selected from coal;

[0046] In this step, the present application introduces a crushing method combining cryogenic freezing and ultrasonic vibration, which specifically includes the following steps:

[0047] First, wash the coal gangue selected from coal to remove surface dust and impurities, and classify it according to the size of the coal gangue;

[0048] Second, put the washed and classified coal gangue into a freezing container, and use liquid nitrogen or other high-efficiency refrigerants (such as liquid helium, liquid hydrogen, etc.) to quickly freeze the coal gangue to reduce the temperature of the coal gangue to between 100°C and 150°C and keep it warm. It should be noted that when the coal gangue is quickly cooled to an extremely low temperature, different components inside the coal gangue will undergo uneven shrinkage due to the thermal expansion and contraction effect, resulting in the formation of internal stress, which in turn triggers microcracks. These cracks help to more easily split the coal gangue into the required particle size during the subsequent crushing process.

[0049] Third, apply high-intensity ultrasonic vibration to the frozen coal gangue in the above low-temperature environment, and use the high-frequency vibration energy generated by the ultrasonic wave to further expand the cracks inside the coal gangue, so that the coal gangue gradually breaks along the cracks into the required fine particle size. In addition, the ultrasonic vibration can also help remove the frost or ice layer that may form on the surface of the coal gangue due to low temperature, ensuring the cleanliness after crushing.

[0050] Finally, quickly transfer the coal gangue treated by ultrasonic wave to a screening system maintained at room temperature, and screen out the fine coal gangue aggregate within a specific particle size range as needed to ensure its suitability for subsequent soaking and chemical modification steps.

[0051] Through cryogenic freezing and ultrasonic-assisted crushing, not only can the crushing degree of the coal gangue be effectively controlled, but also the internal structure of the coal gangue can be improved through the unique combination of cryogenic freezing and ultrasonic vibration, enhancing its adhesion and compatibility with the gelling material, and thus improving the overall performance of the finally prepared spraying material.

[0052] In addition, it should be emphasized that in this application, cryogenic freezing and ultrasonic crushing are used in combination, rather than cryogenic freezing combined with other crushing methods. The reason is that the synergistic effect generated by cryogenic freezing and ultrasonic crushing can more effectively crush coal gangue. Specifically, cryogenic freezing can significantly increase the brittleness of coal gangue, causing microcracks to form in its internal structure due to thermal expansion and contraction. This treatment not only reduces the hardness of coal gangue but also provides favorable conditions for subsequent crushing. Traditional mechanical crushing methods (such as hammering, grinding, etc.) usually require a large external force to crush materials, which often leads to unnecessary mechanical stress damage on the surface or inside of coal gangue, affecting the quality of the final product. In contrast, ultrasonic crushing uses the energy generated by high-frequency vibration to expand the microcracks inside coal gangue without significantly increasing the temperature, enabling the coal gangue to break naturally along these cracks into fine particles, thereby reducing damage to the structure of coal gangue. In addition, the method of cryogenic freezing plus ultrasonic crushing requires less water or other liquid media compared to traditional mechanical crushing, reducing the problem of wastewater treatment. At the same time, due to avoiding violent mechanical actions, it also reduces the operation risk and noise pollution, improving the safety and comfort of the working environment. Through experimental verification, compared with cryogenic freezing combined with traditional crushing methods, after cryogenic freezing treatment, the surface of coal gangue under the action of ultrasonic waves will be rougher and full of microcracks, which is beneficial for subsequent chemical solutions to better penetrate and enhance the modification effect. For example, in the subsequent soaking process, chemical reactions can be carried out more effectively to improve the physical and chemical properties of coal gangue.

[0053] In summary, there is an obvious synergistic effect between cryogenic freezing and ultrasonic crushing. The combination of the two can not only improve the crushing efficiency and product quality but also optimize the effect of subsequent chemical modification, achieving the best comprehensive benefits compared with cryogenic freezing combined with other traditional crushing methods.

[0054] S102: Immerse the crushed coal gangue in an alkaline solution, soak it, and then air-dry it;

[0055] In this step, the alkaline solution may include, for example, any one of saturated lime water, calcium hydroxide, and sodium hydroxide solution.

[0056] In this application, by soaking the crushed coal gangue in an alkaline solution, firstly, new chemical bonds can be formed on the surface of the coal gangue or the number of surface functional groups can be increased, such as hydroxyl groups (~OH), etc., thereby improving the activity of the coal gangue particles and making it easier for them to react with other materials. Secondly, the alkaline solution helps to change the charge state and wetting performance of the coal gangue surface, thereby improving the compatibility and bonding force between the coal gangue and the cementitious material, and making the finally prepared composite spraying material have better uniformity and stability. Thirdly, the alkaline solution can promote changes in the internal microstructure of the coal gangue, such as expanding the porosity, which helps to improve the adsorption capacity and durability of the coal gangue.

[0057] S103: Soak the air-dried coal gangue in a sodium sulfate solution again, and then air-dry it;

[0058] In this step, the reason why the coal gangue soaked and air-dried in the alkaline solution is further soaked in the sodium sulfate solution in this application is as follows: First, the alkaline solution can remove certain impurities in the coal gangue and increase or change the surface functional groups of the coal gangue, while the treatment with the sodium sulfate solution can introduce a new ion exchange environment on the surface of the already adjusted coal gangue particles to form a protective film. For example, sulfate ions (SO4 2 -) will react with some cations on the surface of the coal gangue to form insoluble compounds deposited on the surface, thereby changing its surface charge and wettability. Second, through the treatment with the sodium sulfate solution, a stable compound layer can be formed on the surface of the coal gangue particles, which helps to improve the durability and environmental erosion resistance of the coal gangue-based composite material. Third, after the treatment with the sodium sulfate solution, the compatibility between the coal gangue and other additives can be improved, especially for the cementitious material system containing calcium, magnesium and other ions. The presence of sodium sulfate can adjust the ion balance in the cementitious material system, prevent unnecessary precipitation reactions from occurring, and promote the formation of a more uniform mixture. Fourth, soaking in the sodium sulfate solution can also prepare for the subsequent spraying of the calcium chloride solution. When the coal gangue is treated with the sodium sulfate solution and then sprayed with the calcium chloride solution, a double decomposition reaction will occur between the two to generate water-insoluble calcium sulfate (gypsum), which helps to seal the tiny cracks on the surface of the coal gangue, enhance the structural strength of the coal gangue and improve the mechanical properties of the final product.

[0059] In summary, the alkaline solution treatment mainly focuses on cleaning and preliminary modification of the coal gangue, while the sodium sulfate solution treatment pays more attention to optimizing the surface characteristics of the coal gangue, enhancing stability and laying a foundation for subsequent treatment. By adopting this double treatment method, it can ensure that the coal gangue fine aggregate shows the best effect in the preparation of the spraying material.

[0060] S104: Spray a calcium chloride solution on the coal gangue that has been air-dried again, and then stack and age it after air-drying to obtain the modified coal gangue fine aggregate.

[0061] In this step, by spraying a calcium chloride solution onto the coal gangue that has been soaked in a sodium sulfate solution and dried, the surface of the coal gangue can be further modified to enhance its physical and chemical properties. Specifically, when the calcium chloride solution is sprayed onto the coal gangue that has been treated with the sodium sulfate solution and dried, a double decomposition reaction occurs between the two, generating calcium sulfate (CaSO4) that is insoluble in water. Calcium sulfate is a mineral with relatively high hardness, which can form a protective film on the surface of the coal gangue or fill in tiny cracks, thereby increasing the strength and stability of the coal gangue. In addition, the generated calcium sulfate is deposited on the surface and internal micropores of the coal gangue, helping to seal these micropores, which can reduce the porosity inside the coal gangue. In this way, not only can the overall density and mechanical strength of the coal gangue particles be improved, but also the bonding performance between the coal gangue and the cementitious material can be enhanced. Further, after being soaked in the sodium sulfate solution and dried, tiny crystals or precipitates (such as Na2SO4) will form on the surface of the coal gangue. The presence of these substances can increase the surface roughness of the coal gangue. Good surface roughness can provide more attachment points for the phosphor and glass beads to enhance the physical embedding effect, thereby improving the adhesion of the phosphor and glass beads on the surface of the coal gangue, and further enhancing the luminescence performance of the spraying material.

[0062] After the coal gangue is soaked in the sodium sulfate solution and dried, the present application provides a creative aging method, which specifically includes the following steps:

[0063] First, after spraying the calcium chloride solution onto the dried coal gangue, it is left to stand at room temperature for 24 h to allow the initial chemical reaction to occur and ensure the uniform distribution of the solution on the surface and in the pores.

[0064] Second, the coal gangue treated as above is placed in an environment where the humidity can be precisely controlled. First, the relative humidity is set to 70% - 80% and maintained for 24 h to promote the slow formation of calcium sulfate crystals and fill in tiny cracks; then the humidity is reduced to 30% - 40% and maintained for 12 h to help remove excess moisture and prevent the structure from becoming loose due to excessive crystallization. The temperature is changed every 48 h, gradually increasing from room temperature (about 25°C) to 60°C and maintaining for 12 h, and then slowly cooling back to room temperature. This temperature change helps to promote the uniform growth of calcium sulfate crystals and can help release internal stress to avoid cracks caused by rapid drying. It should be noted that during the humidity and temperature cycling process, a trace amount of specific gases (such as carbon dioxide CO2 or ammonia NH3) can be introduced appropriately. These gases can react with the compounds formed on the surface of the coal gangue to generate by-products such as carbonates or ammonium salts. These by-products can, to a certain extent, adjust the surface pH value and increase the surface active sites, which is beneficial for subsequent combination with other additives (such as phosphor, glass bead reflective powder).

[0065] Next, during each temperature or humidity adjustment, a slight ultrasonic vibration or mechanical vibration (with a frequency range selectable from 20 kHz to 100 kHz) is applied to the stacked coal gangue. This not only accelerates the evaporation of moisture and other volatile substances, but also promotes a more uniform distribution of calcium sulfate crystals on the surface and within the pores of the coal gangue, improving the consistency and stability of the material.

[0066] Finally, continue the aging process for at least 7 days under constant conditions (such as a relative humidity of 50% ± 5% and a temperature of 25°C ± 2°C) to ensure that all chemical reactions are completely finished and the material reaches its optimal state.

[0067] This application compared the spraying materials obtained by processing coal gangue based on the above aging method with those obtained by traditional aging methods, as shown in Table 3 specifically:

[0068] Table 3

[0069]

[0070]

[0071] As can be seen from Table 3, by adopting the aging method proposed in this application, the spraying materials obtained have significantly improved in various properties.

[0072] In another exemplary embodiment, in step S200, the preparation of the gelling material includes the following steps:

[0073] S201: Perform surface pretreatment on the phosphor and glass microspheres;

[0074] In this step, this application performs surface pretreatment (for example, through a chemical reaction between a coupling agent and the phosphor and glass microspheres to increase the active sites on the surface of the phosphor and glass microspheres, facilitating better binding with the coating material) and coating treatment (for example, suspending the phosphor or glass microspheres in a solution containing a coating material (such as an organic polymer like polyvinyl alcohol or an inorganic nanomaterial like silica), and under appropriate conditions, enabling the coating material to be uniformly deposited on the particle surface) on the phosphor and glass microspheres. By performing surface pretreatment and coating treatment on the phosphor and glass microspheres, the dispersibility of the phosphor and glass microspheres and the interfacial bonding force with the matrix can be significantly improved, avoiding the agglomeration problem of traditional mechanical mixing.

[0075] S202: Place the lithium slag powder in a low-temperature plasma reactor, and perform high-frequency discharge treatment at 10 kHz to 20 kHz for 30 min to 60 min under an argon atmosphere to break the chemical bonds on its surface and generate active free radicals, enhancing its chemical bonding with cement, thereby being able to improve the early strength and durability;

[0076] S203: Add cement, silica fume, activated lithium slag powder, and bentonite into a microwave reactor, and mix them for 5 min to 10 min under a microwave power of 500 W to 800 W to trigger the micro-area hydration reaction between particles. After the reaction is completed, a mixture is obtained.

[0077] S204: Add the phosphor with nano-coating and glass microspheres to the mixture in steps, and perform ultrasonic dispersion synchronously after each addition, thereby obtaining the cementitious material.

[0078] In this step, for example, the phosphor and glass microspheres processed based on step S201 can be added to the mixture in three times, and 40 kHz ultrasonic dispersion is applied synchronously after each addition. The total mixing time does not exceed 15 min.

[0079] It should be noted that due to the small particle size and high surface energy of the phosphor and glass microspheres, they are extremely prone to agglomeration. If a large amount of phosphor and glass microspheres are added to the mixture at one time, it will cause the agglomerates to be difficult to fully disperse, reducing the functionality (such as luminescence efficiency, reflective performance). After adding in three times and synchronously processing with 40 kHz ultrasonic waves each time, the agglomeration can be gradually broken, ensuring that each batch of particles is fully dispersed before mixing. According to experimental data, this method reduces the standard deviation of the particle size distribution of the phosphor from 2.5 in the traditional process to 0.8, greatly improving its uniformity.

[0080] In another exemplary embodiment, in step S300, the step of stirring the modified coal gangue fine aggregate, the cementitious material, and water to obtain the coal gangue-based composite spraying material includes the following steps:

[0081] S301: Initially mix the modified coal gangue fine aggregate and the cementitious material at a low speed using a mechanical stirrer under normal pressure to obtain a mixture.

[0082] In this step, the cementitious material needs to be added in batches gradually, and fully stirred evenly after each addition, which is beneficial to reducing the agglomeration phenomenon.

[0083] S302: Transfer the mixture to a stirring device with a vacuum function, and continue stirring under reduced pressure (for example, the vacuum degree reaches -0.08 MPa). Vacuum stirring helps to remove the bubbles generated during the mixing process, avoid pore formation, and improve the density and strength of the final material. Among them, the stirring speed and time can be adjusted according to the actual situation. For example, the stirring speed can be set to 60 - 120 revolutions per minute, and the duration can be set to 5 min to 10 min.

[0084] S303: While performing vacuum stirring, gradually add a predetermined amount of water and maintain the stirring state. During the process of adding water, ultrasonic dispersion is performed to obtain the coal gangue-based composite spraying material.

[0085] In this step, the water added in this application is magnetized water. It should be noted that when water is magnetized, some hydrogen bonds in the water molecular clusters are broken, and the water is split into single water molecules or water molecular clusters with fewer water molecules. In addition, water molecules are strongly polar molecules. After water is magnetized, the polar state is improved, resulting in a decrease in the surface tension and viscosity of the magnetized water and an increase in its activity. The working performance of the coal gangue-based composite spraying material prepared with magnetized water is improved, and the strength is increased. On the premise of ensuring the same working performance, the dosage of water reducing agent can be effectively reduced, thus reducing the production cost.

[0086] In this application, the performance comparison of the spraying materials prepared with magnetized water and ordinary tap water was carried out under the same water-cement ratio, as shown in Table 4 specifically:

[0087] Table 4

[0088] Performance index Magnetized water (experimental group) Ordinary tap water (control group) Compressive strength (MPa) ≥30 27 Wear resistance (mg weight loss) ≤50 60 Dosage of water reducing agent (%) 0.17 0.3

[0089] As can be seen from Table 4, under the same water-cement ratio, the experimental group achieved higher compressive strength by using magnetized water, indicating that magnetized water is helpful for the strength development of the spraying material; the experimental group showed better wear resistance, meaning that the material surface is more durable and suitable for long-term use; the dosage of water reducing agent in the experimental group decreased significantly, indicating that magnetized water can effectively improve the workability of the spraying material and further reduce the production cost of the spraying material.

[0090] It should also be noted that in this application, the method of adding water step by step instead of adding it all at once can better control the consistency and fluidity of the mixture and prevent caking. At the same time, when adding water, start the ultrasonic dispersion device. Ultrasonic waves can generate high-frequency vibrations, effectively breaking the agglomeration between particles. Especially for fine and easily aggregated additives such as phosphor powder and glass microspheres, a more uniform dispersion effect can be achieved. It should also be noted that in addition to starting the ultrasonic dispersion device, this application also introduces a pulse jet technology, that is, the agglomeration between particles is broken by intermittent high-pressure water flow impact to improve the dispersion effect of each component in the mixture.

[0091] In this step, the water-cement ratio of the mixture and water is set to 0.4-0.6, preferably 0.5. The water-cement ratio directly affects the working performance of the mixture. If the water-cement ratio is too low (less than 0.4, i.e., the amount of water is too small), the mixture will be too viscous and difficult to be uniformly stirred and evenly laid; on the contrary, if the water-cement ratio is too high (greater than 0.6, i.e., the amount of water is too large), it will lead to excessive fluidity of the mixture and be difficult to maintain its shape. Therefore, choosing a water-cement ratio within the range of 0.4-0.6 can ensure that the mixture has good fluidity and plasticity. In addition, through experimental verification, the present application finds that a water-cement ratio of 0.5 is the most ideal value within this range. At this ratio, the most ideal interaction relationship can be formed between the modified fine coal gangue aggregate and the cementitious material, which can not only effectively fill the voids, but also maintain appropriate density and fluidity. In addition, a water-cement ratio of 0.5 can also bring the most stable changes in physical and chemical properties, ensuring the consistency and reliability of product quality.

[0092] Next, the present application makes a detailed performance comparison between the spraying material prepared by the method described in the present application and the existing spraying materials. The specific comparison results are shown in Table 5 as follows:

[0093] Table 5

[0094]

[0095] Table 5 shows the comparison of the key performance indicators between the coal gangue-based composite spraying material prepared in the present application and two existing spraying materials (traditional mortar type and synthetic resin type). It can be seen from Table 2 that, compared with the existing spraying materials, the coal gangue-based composite spraying material prepared in the present application shows superior or comparable performance in terms of compressive strength, abrasion resistance, and initial and persistent luminescence coefficients. Especially, it shows significant advantages in environmental protection and cost-effectiveness. This material not only uses the waste coal gangue to reduce environmental pollution, but also has a lower cost because of using cheap and abundant raw materials. These characteristics make the coal gangue-based composite spraying material a very promising new material option for environmental protection and economic efficiency, suitable for spraying reinforcement and improving visibility in dark environments.

[0096] Figure 2 is a schematic diagram of the existing ordinary spraying material under light conditions; Figure 3 is a schematic diagram of the existing ordinary spraying material under dark conditions; Figure 4 is a schematic diagram of the spraying material prepared in the present application under light conditions; Figure 5 is a schematic diagram of the spraying material prepared in the present application under dark conditions. Figures 2 to 5It can be seen that the spraying material prepared in this application is basically the same in appearance as the existing spraying material under light conditions, without obvious differences. However, in a dark environment, the existing spraying material has no luminous brightness and is completely dark, while the spraying material prepared in this application has obvious luminous brightness in a dark environment after being irradiated under light conditions. In summary, compared with the existing ordinary spraying materials, the coal gangue-based composite spraying material in this application not only has improved physical properties, but also greatly enhanced visibility in a dark environment, which benefits from the uniformly dispersed fluorescent components inside, ensuring a long-term stable and reliable luminous effect. This characteristic makes it particularly suitable for applications that require high visibility and durability.

[0097] The above are only the preferred embodiments of this application, and do not limit the patent scope of this application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of this application.

Claims

1. A coal gangue-based composite spraying material, characterized in that The spraying material includes: Modified coal gangue fine aggregate and cementitious material, wherein The mortar ratio of the cementitious material to the modified coal gangue fine aggregate is 0.4 - 0.6:

1.

2. The coal gangue-based composite spraying material according to claim 1, characterized in that, By mass, the cementitious material includes: Cement: 400 - 700 parts; Silica fume: 50 - 100 parts; Lithium slag powder: 10 - 40 parts; Bentonite: 1 - 5 parts; Phosphor powder: 1 - 20 parts; Glass microsphere reflective powder: 1 - 10 parts; Water reducing agent: 1 - 3 parts.

3. A preparation method of a coal gangue-based composite spraying material, characterized in that, The preparation method includes: Preparing to obtain the modified coal gangue fine aggregate; Preparing to obtain the cementitious material; Stirring the modified coal gangue fine aggregate, the cementitious material and water to obtain a coal gangue-based composite spraying material.

4. The preparation method of a coal gangue-based composite spraying material according to claim 3, characterized in that, The preparation to obtain the modified coal gangue fine aggregate includes: Crushing the coal gangue selected from coal; Soaking the crushed coal gangue in an alkaline solution and drying it; Soaking the dried coal gangue in a sodium sulfate solution again and drying it; Spraying a calcium chloride solution on the surface of the coal gangue after drying it again, drying and aging it to obtain the modified coal gangue fine aggregate.

5. The preparation method of a coal gangue-based composite spraying material according to claim 4, characterized in that, Crushing the coal gangue selected from coal by combining low-temperature freezing and ultrasonic vibration.

6. The preparation method of a coal gangue-based composite spraying material according to claim 4, wherein, The alkaline solution includes any one of the following: saturated lime water, calcium hydroxide and sodium hydroxide solution.

7. The preparation method of a coal gangue-based composite spraying material according to claim 3, characterized in that, The preparation to obtain the cementitious material includes: Performing surface pretreatment on the phosphor powder and the glass microspheres; Performing plasma activation on the lithium slag powder: Mixing cement, silica fume, the activated lithium slag powder and bentonite under the action of microwave to obtain a mixture; Adding the phosphor powder and glass microspheres that have completed nano-coating to the mixture in steps, and performing ultrasonic dispersion synchronously after each addition to obtain the cementitious material.

8. The preparation method of a coal gangue-based composite spraying material according to claim 3, wherein The step of stirring the modified coal gangue fine aggregate, the cementitious material and water to obtain a coal gangue-based composite spraying material includes: Stirring and mixing the modified coal gangue fine aggregate and the cementitious material to obtain a mixture; Continuing to perform vacuum stirring on the mixture; While performing vacuum stirring, gradually adding a predetermined amount of water and maintaining the stirring state, and performing ultrasonic dispersion during the process of adding water to obtain a coal gangue-based composite spraying material.

9. The preparation method of a coal gangue-based composite spraying material according to claim 8, wherein The water-cement ratio of the mixture and water is 0.4 to 0.

6.

10. The preparation method of a coal gangue-based composite spraying material according to claim 8, characterized in that, The added water is magnetized water.

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