Method and process for preparing new roadway thin-spraying material based on mine solid waste utilization

Abstract

The invention belongs to the technical field of mine engineering and solid waste resource utilization, and relates to a preparation method and process of a new roadway thin-blasting material based on mine solid waste utilization, and the new roadway thin-blasting material takes mine solid wastes (such as gold tailings) generated in a mineral separation process as main aggregates and fillers; cement, styrene-butadiene emulsion, polyvinyl alcohol fibers, hydroxypropyl methyl cellulose, a cement accelerator, a polycarboxylate superplasticizer, a dodecanol ester film-forming agent, a KH550 silane coupling agent and water are combined, and the new roadway thin-spraying material is obtained through compounding and process design and is used for surface sealing, weathering prevention, air leakage prevention, reinforcement and supporting of mine roadways, chambers, working faces and side slopes; compared with a traditional shotcrete material, the shotcrete material has the remarkable advantages in the aspects of resource utilization efficiency, economic cost, mechanical property and construction adaptability, three-in-one technical integration of solid waste recycling, supporting high efficiency and cost controllability is achieved, and a solution with both environmental benefits and economic benefits is provided.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering and solid waste resource utilization technology, and specifically relates to a method and process for preparing a new type of thin-film spraying material for mine roadways based on the utilization of mine solid waste. Background Technology

[0002] In metal mines, especially gold mines, a large amount of solid waste—gold tailings—is generated during mining and beneficiation. This tailings is typically discharged into tailings ponds in slurry form, occupying significant land resources and posing potential safety and environmental risks such as dust pollution, heavy metal ion migration, and dam instability. How to utilize gold tailings on a large scale and with high added value is one of the key issues urgently needing to be addressed to achieve sustainable development in the mining industry. Currently, the comprehensive utilization rate of gold tailings remains low; therefore, developing new building materials that can efficiently consume gold tailings has significant environmental and resource recycling value.

[0003] Meanwhile, the stability of the surrounding rock in underground engineering projects such as roadways and chambers is crucial during mine construction and production. Thin-layer shotcrete support technology, as an efficient surface sealing and active support method, can effectively prevent weathering and spalling of the surrounding rock, seal cracks, prevent air leakage, and has a certain load-bearing and toughening effect. Traditional shotcrete materials have problems such as large cement consumption, high material cost, large dust, high rebound rate, slow early strength development, easy cracking, and insufficient adhesion to the surrounding rock. Moreover, its spraying thickness is usually large (about 100mm), resulting in large material consumption per unit area and high overall cost.

[0004] Applying gold tailings to mine shotcrete materials can achieve "waste treatment and turning waste into treasure," enabling large-scale solid waste disposal, reducing tailings treatment costs, and providing economical and efficient support materials for mines, resulting in significant environmental and economic benefits. However, the physicochemical properties of gold tailings (such as particle morphology, gradation, and surface activity) differ significantly from those of natural river sand or manufactured sand. Direct large-scale substitution may lead to the new material's workability, mechanical properties, and durability failing to meet the stringent requirements of mine shotcrete support. Especially for engineering applications requiring rapid support, the early strength development rate of the material is crucial.

[0005] While there is considerable research on thin-layer sprayed materials in the existing technology, there is still a lack of systematic formulation research that balances the rapid development of early strength and long-term durability while achieving high utilization of gold tailings. For example, some patents emphasize the toughening effect of polymers but neglect the guarantee of early strength; others focus on rapid setting effects, but the amount of solid waste added is limited or the material toughness is insufficient. In addition, existing thin-layer sprayed materials often fail to achieve a good balance between cost control and performance optimization, resulting in economic constraints in their practical application. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, the present invention aims to provide a method and process for preparing a new type of thin-layer shotcrete material for mine roadways based on the utilization of mine solid waste. The new thin-layer shotcrete material prepared by this method uses gold tailings as the main component. Through scientific proportioning design and composite modification with various functional additives (polyvinyl alcohol fiber, hydroxypropyl methylcellulose, cement accelerator, styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent), it achieves effective utilization of gold tailings while possessing excellent early strength development performance, good workability, and outstanding long-term mechanical properties and durability, meeting the various requirements of mine thin-layer shotcrete support.

[0007] To address the aforementioned technical problems, this invention provides a method for preparing a novel thin-film spraying material for mine roadways based on the utilization of mine solid waste, comprising the following steps: Gold tailings, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose, and cement accelerator were mixed evenly to obtain a dry-mixed mixture. The mass ratio of gold tailings to cement was 3:7, and the dosages of polyvinyl alcohol fiber, hydroxypropyl methylcellulose, and cement accelerator were 0.3%, 0.1%, and 8% of the total mass of gold tailings and cement, respectively. Add water at a water-cement ratio of 0.45, then add styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent to the water in sequence, and disperse evenly to obtain a mixture. The dosages of styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent are 10%, 0.5%, 1%, and 1% of the total mass of gold tailings and cement, respectively. After pouring the liquid into the dry mixture, heat and stir until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new material for thin spraying in tunnels.

[0008] The method for preparing a new type of thin-film shotcrete material for roadways based on the utilization of mine solid waste presented in this invention has significant advantages over traditional shotcrete materials in terms of resource utilization efficiency, economic cost, mechanical properties, and construction adaptability.

[0009] In terms of solid waste resource utilization, this invention achieves a high proportion of gold tailings disposal and functional utilization, promotes the closed-loop recycling of mine solid waste, and aligns with the concepts of green mining and sustainable development.

[0010] In terms of economic benefits, the thickness of the new thin-film spraying material for tunnels can be controlled at around 10mm, which is only 1 / 10 of that of traditional sprayed concrete (usually ≥100mm). This results in a 41.7% reduction in material cost per unit area compared to traditional sprayed concrete, demonstrating good engineering economics and promotion potential.

[0011] In terms of material properties, the new thin-layer shotcrete material for roadways exhibits excellent early strength development characteristics and long-term mechanical stability: compressive strengths at 3 days, 7 days, and 28 days reach 5.0 MPa, 20.8 MPa, and 29.6 MPa, respectively; flexural strengths are 1.1 MPa, 4.1 MPa, and 6.6 MPa, respectively. The new thin-layer shotcrete material for roadways has a suitable setting time (initial setting 120 min, final setting 200 min), good workability and spray compatibility, and also possesses excellent toughness and interfacial bonding properties, effectively inhibiting cracking and improving the overall integrity of the support system.

[0012] Gold tailings are mainly composed of SiO2 and Al2O3, and have certain potential activity. High-volume gold tailings can be mixed with cement (ordinary Portland cement) and 8% high-efficiency quick-setting agent can be added as an "engine" to actively stimulate and accelerate the hydration process of the entire system (including the micro-reaction on the surface of cement and gold tailings). This is a strength development path tailored for low-activity aggregates.

[0013] The added styrene-butadiene emulsion (polymer emulsion) and dodecyl alcohol ester film-forming agent can form a continuous and dense polymer film in the slurry, effectively encapsulating the gold tailings particles and improving overall toughness and impermeability. One end of the KH550 silane coupling agent can bind to inorganic materials such as gold tailings and cement hydration products, while the other end binds to the styrene-butadiene emulsion polymer, acting as a "molecular bridge." This fundamentally solves the problem of weak interfaces between gold tailings and organic polymers, which is key to achieving high bond strength. The added PVA fiber's hydrophilicity improves compatibility with the cement matrix, ensures uniform dispersion, and provides superior crack bridging performance.

[0014] The mass ratio of gold tailings to cement is 3:7, ensuring effective utilization of the gold tailings while providing sufficient cementitious components to guarantee the early and later strength framework of the material system. The water-cement ratio is 0.45, meaning the water mass is 45% of the cement mass. This optimized water-cement ratio ensures sufficient fluidity and workability of the slurry to meet pumping and spraying requirements, and also allows for the formation of a dense microstructure through the synergistic effect of water-reducing agents and functional additives, ensuring good mechanical properties of the material. Styrene-butadiene emulsion, at a dosage of 10% of the total mass of gold tailings and cement, acts as a polymer modifier, significantly affecting the flexibility, adhesion, and crack resistance of the new thin-film shotcrete material for roadways. A 10% dosage forms a continuous and tough polymer film that effectively penetrates the pores and cracks of the cement paste, greatly improving the material's deformation capacity, cohesive strength, and adhesion to different substrates (such as rock and concrete). Adding 0.3% polyvinyl alcohol fiber (PVA fiber) by weight of the total mass of tailings and cement utilizes the excellent hydrophilicity, high tensile strength, and high elastic modulus of PVA fiber. Its uniform dispersion in the slurry effectively bridges microcracks, limiting crack initiation and propagation, and significantly improving the toughness, impact resistance, and resistance to drying shrinkage cracking of the new roadway thin-layer shotcrete. Adding 1% silane coupling agent by weight of the total mass of tailings and cement enables effective molecular bridging between inorganic materials (such as cement hydration products and tailings particles) and organic polymers (such as styrene-butadiene emulsion), significantly improving interfacial adhesion and enhancing the overall performance and durability of the new roadway thin-layer shotcrete. Adding 0.1% hydroxypropyl methylcellulose (HPMC) by weight of the total mass of tailings and cement acts as a water-retaining agent and thickener, effectively improving the uniformity, stability, and anti-bleeding properties of the slurry, ensuring good adhesion and workability of the new roadway thin-layer shotcrete during construction and reducing rebound loss. The introduction of a cement accelerator at a dosage of 8% of the total mass of tailings and cement is key to achieving rapid early strength development in the material. It significantly accelerates the hydration reaction rate of cement minerals, shortens setting time, and enables the new thin-film shotcrete material for roadways to achieve high early strength within hours to days, meeting the needs of rapid support engineering. This involves using ordinary Portland cement with a high dosage of tailings and an external addition of 8% high-efficiency accelerator as an "engine" to actively stimulate and accelerate the hydration process of the entire system (including micro-reactions on the surfaces of cement and tailings). The addition of a polycarboxylate superplasticizer at a dosage of 0.5% of the total mass of tailings and cement provides high water reduction and good dispersion stability, effectively improving the fluidity and pumpability of the slurry. While ensuring workability, it reduces the actual water-cement ratio, increases slurry density, optimizes pore structure, and enhances the mechanical strength and durability of the new thin-film shotcrete material for roadways.Adding a dodecyl alcohol film-forming agent at a dosage of 1% of the total mass of gold tailings and cement helps polyvinyl alcohol fiber, hydroxypropyl methylcellulose, cement accelerator, styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent and KH550 silane coupling agent to form a continuous and dense polymer film during the drying and curing process of the slurry, thereby enhancing the integrity, flexibility and sealing performance of the material.

[0015] Preferably, the particle size of the gold tailings is set to 0 < particle size ≤ 70 μm, and the length of the polyvinyl alcohol fiber is 3 mm. If the polyvinyl alcohol fiber is too long, it will affect stirring, easily clump together with the slurry, and cannot be fully and evenly distributed.

[0016] The particle size of the gold tailings is limited to 0 < particle size ≤ 70 μm because gold tailings within this size range have a large specific surface area, making them easier to react with cement. However, they also tend to absorb water, agglomerate, and settle. Therefore, hydroxypropyl methylcellulose (HMC) is added as a water-retaining and thickening agent. Its water-retaining properties significantly improve the cohesiveness and suspension stability of the slurry, ensuring uniform dispersion of the gold tailings particles. This is a prerequisite for achieving good workability and a homogeneous final sprayed layer. Furthermore, KH550 silane coupling agent is introduced to strengthen the interfacial bonding between the gold tailings particles, cement, and polymer. Styrene-butadiene emulsion and a film-forming agent are used to form a continuous polymer film that encapsulates the gold tailings particles, improving adhesion and toughness. PVA fiber bridging and HPMC water retention prevent slurry segregation and improve workability.

[0017] Preferably, the cement accelerator is an alkali-free or low-alkali accelerator to meet environmental protection requirements and reduce the impact on long-term strength; the viscosity of hydroxypropyl methylcellulose is 200,000 mPa·s, and the cement is P.O42.5 grade ordinary Portland cement.

[0018] Preferably, the mixing steps for preparing the dry mixture are as follows: the gold tailings, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose and cement quick-setting agent are first dry mixed at 55r / min~65r / min for 1min~2min to initially mix the materials, and then dry mixed at a mixing speed of 115r / min~125r / min for 1min~2min.

[0019] Preferably, the stirring speed during the preparation of the mixture is 115 r / min to 125 r / min, and the stirring time is 1 min to 2 min.

[0020] Preferably, the heating temperature for preparing the new thin-spray material for roadways is 19℃~21℃. When preparing the new thin-spray material for roadways, the material is first stirred at a stirring speed of 55r / min~65r / min for 2min~3min; then stirred at a stirring speed of 115r / min~125r / min for 2min~3min.

[0021] Preferably, the cement accelerator is an alkali-free accelerator or a low-alkali accelerator. This is to meet environmental protection requirements and reduce the impact on the long-term strength of the new thin-film shotcrete material in the roadway.

[0022] This invention provides a method for preparing a new type of roadway thin-spray material based on the utilization of mine solid waste.

[0023] This invention provides a thin-spraying process for a new material for tunnel thin-spraying, which can be a manual spray gun thin-spraying process or a robotic arm spray gun thin-spraying process. When using the manual spray gun thin spraying process, the new roadway thin spraying material is prepared according to the preparation method of the new roadway thin spraying material based on the utilization of mine solid waste, and the new roadway thin spraying material is pumped to the manual spray gun. The thin spraying material is sprayed from top to bottom in a layered and segmented manner. After spraying, it is trimmed and watered for curing before final setting to form a spray layer. When using the robotic arm spray gun thin spraying process, the new thin spraying material for roadways is prepared according to the preparation method of the new thin spraying material based on the utilization of mine solid waste. The cement quick-setting agent is not added temporarily. The prepared thin spraying material is pumped to the nozzle of the robotic arm spray gun, and the cement quick-setting agent is added at the nozzle of the robotic arm spray gun. After the thin spraying material is initially sprayed in layers, it is sprayed again. After spraying, the surface is repaired and moisturized to form a spray layer.

[0024] This invention provides the application of a novel thin-film spraying material for surface sealing, weathering prevention, air leakage prevention, reinforcement, and support in mine roadways, chambers, working faces, and slopes.

[0025] Preferably, during construction, a thin-layer spraying device for a special roadway thin-layer spraying material can be used to control the spraying thickness to 10mm and the spraying time to 60min.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: The new thin-layer shotcrete material for roadways prepared by the method of this invention uses gold tailings as the main raw material, realizing the efficient resource utilization of mineral processing solid waste. Each cubic meter of material can consume a large amount of gold tailings, significantly reducing the land occupation and environmental risks caused by tailings storage, which is in line with the policy orientation of green mining and circular economy, promotes large-scale solid waste disposal, and improves environmental protection benefits. At the same time, the components in the preparation of the new thin-layer shotcrete material for roadways, except for cement, gold tailings, and water, have clear functions and coordinated proportions. Through multiple synergistic pathways such as rapid setting, reinforcement, and toughening, the performance of the new thin-layer shotcrete material for roadways is optimized and balanced. The efficient role of cement accelerator and the overall synergy of the components in the formula enable the new thin-layer shotcrete material for roadways to achieve a compressive strength of 5.0 MPa within 3 days, a compressive strength of over 20.8 MPa at 7 days, and a further increase to 29.6 MPa at 28 days. It can quickly provide effective active support for the surrounding rock of underground engineering, significantly shorten the support cycle, and improve construction efficiency and safety. The composite toughening effect of PVA fiber and styrene-butadiene emulsion in the component formulation enables the new thin-layer sprayed material for roadways to exhibit both high strength and good toughness. The combined effect of styrene-butadiene emulsion and KH550 coupling agent greatly enhances the bonding strength between the thin-layer sprayed layer and various substrates (such as rock, concrete, and metal mesh), ensuring the integrity of the support system. Through the optimization of the water-cement ratio and the synergistic effect of polyvinyl alcohol fiber, hydroxypropyl methylcellulose, cement accelerator, styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent, a dense slurry structure and a continuous polymer film are formed, effectively reducing the material's permeability and giving it excellent weathering and impermeability. Through the water-retaining and thickening effect of hydroxypropyl methylcellulose (HPMC) and the plasticizing effect of polycarboxylate superplasticizer, the material has good fluidity, cohesiveness, and water retention at a water-cement ratio of 0.45, with low rebound rate and high adhesion rate during spraying, thus improving the working environment. This allows the final prepared tunnel thin-layer spraying material to maintain excellent performance while effectively controlling material costs through solid waste utilization and thin-layer spraying design, thus promoting the large-scale application of this technology in mine support.

[0027] The thin-sprayed material prepared in this invention exhibits remarkably rapid early strength development: a moderate setting time (at room temperature 20℃), with initial setting of 120 min and final setting of 200 min, providing a good operational window for construction; the flexural strength reaches 1.1 MPa and the compressive strength reaches 5.0 MPa at 3 days; by 7 days, the flexural strength rapidly increases to 4.1 MPa and the compressive strength reaches as high as 20.8 MPa; at 28 days, the flexural strength further reaches 6.6 MPa and the compressive strength reaches 29.6 MPa. Particularly noteworthy is the excellent early development trend of flexural strength, reflecting the material's good toughness and crack resistance potential. This rapid strength increase is the result of the synergistic effect of multiple factors, but the addition of cement accelerators is the most crucial accelerating factor. Accelerators significantly advance the hydration exothermic peak and shorten the setting time by strongly promoting the rapid hydration of minerals such as C3A and C3S in cement, enabling the slurry to form a large amount of strong hydration product skeleton in the early stages. Meanwhile, the incorporation of polycarboxylate superplasticizer optimized the actual water-cement ratio while ensuring workability, improved the paste density, and provided superior matrix conditions for strength development. The polymer film formed by styrene-butadiene emulsion during cement hydration intertwines with the cement hydration products, constituting an organic-inorganic composite reinforcing network. This network not only contributes to early strength and adhesion but, more importantly, improves the material's microstructure and reduces defects. KH550 silane coupling agent strengthens the interfacial bonding between the inorganic and organic phases, making stress transfer more efficient. Therefore, the dominant role of the accelerator, combined with the synergistic reinforcing effects of the superplasticizer, polymer emulsion, and coupling agent, leads to a rapid increase in the material's early strength.

[0028] The new thin-film spraying material for roadways prepared by this invention has a coating thickness of only 10% of that of traditional sprayed concrete, and the area that can be covered by a unit volume of material is increased by 10 times. The material cost per unit area is reduced by about 41.7%, and the overall construction cost advantage is obvious. It is suitable for large-area roadway surface support. Attached Figure Description

[0029] Figure 1 The diagram shows the unit area cost of the new thin-film sprayed concrete material for roadways prepared in Example 1 of the present invention and the conventional sprayed concrete prepared in Comparative Example 1.

[0030] Figure 2 The test diagrams show the compressive strength of the new thin-film sprayed concrete material for roadways prepared in Example 1 of the present invention and the conventional sprayed concrete prepared in Comparative Example 1.

[0031] Figure 3 The test diagrams show the flexural strength of the new thin-film shotcrete material for roadways prepared in Example 1 of the present invention and the conventional shotcrete prepared in Comparative Example 1.

[0032] Figure 4 This is a flowchart of the process for using a manual spray gun for thin spraying.

[0033] Figure 5 This is a flowchart of the thin-spray process using a robotic arm spray gun. Detailed Implementation

[0034] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0035] It should be noted that when numerical ranges are involved in this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in Examples 1 to 4, preferred embodiments are described in this invention to avoid redundancy. However, this invention is not limited to these, but can be implemented in other ways within the scope of the technical solutions defined in the appended claims. All raw materials, reagents, instruments, and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0036] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] The new roadway thin-layer spraying material prepared in this invention is used for surface sealing, weathering prevention, air leakage prevention, reinforcement, and support of mine roadways, chambers, working faces, and slopes. When applying thin-layer spraying, either a manual spray gun process or a robotic arm spray gun process can be used. When using the manual spray gun process, the new roadway thin-layer spraying material is prepared according to the method for preparing roadway thin-layer spraying materials based on the utilization of mine solid waste. This material is then pumped to the manual spray gun, and sprayed in a top-down, layered, and segmented manner. After spraying, pre-setting trimming and water curing are performed to form a sprayed layer. The specific process flow diagram is shown below. Figure 4 As shown.

[0038] When using the robotic arm spray gun thin-spraying process, the new thin-spraying material for roadways based on the utilization of mine solid waste is prepared according to the preparation method given in Examples 1-9, without adding cement accelerator. The prepared thin-spraying material is pumped to the nozzle of the robotic arm spray gun, and cement accelerator is added at the nozzle. After initial layering spraying, the thin-spraying material is sprayed again. After spraying, surface finishing and moisture curing are performed to form a spray layer. The specific process flow diagram is shown below. Figure 5 As shown, the two thin-layer spraying processes can be selected according to actual needs.

[0039] Example 1 A method for preparing a novel thin-film sprayed material for mine roadways based on the utilization of mine solid waste includes the following steps: The following steps were taken: the mass ratio of gold tailings to P.O42.5 grade ordinary Portland cement was 3:7; the dosage of 3mm long polyvinyl alcohol fiber was 0.3% of the total mass of gold tailings and cement; the dosage of hydroxypropyl methylcellulose with a viscosity of 200000mPa·s was 0.1% of the total mass of gold tailings and cement; and the dosage of cement accelerator was 8% of the total mass of gold tailings and cement. Gold tailings with a particle size of 0 < ≤ 70μm, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose and cement accelerator were accurately weighed and dry-mixed at 60r / min for 1min to initially mix the materials. Then, the materials were dry-mixed at 120r / min for 2min until a uniform dry mixture was obtained. Based on a water-cement ratio of 0.45, calculate and measure the water. Then, weigh out the following: styrene-butadiene emulsion (SBE) at 10% of the total mass of tailings and cement; polycarboxylate superplasticizer at 0.5% of the total mass of tailings and cement; dodecyl alcohol ester film-forming agent at 1% of the total mass of tailings and cement; and KH550 silane coupling agent at 1% of the total mass of tailings and cement. Stir at 120 r / min for 2 min to uniformly disperse the mixture. After slowly and evenly pouring the mixture into the dry mixture, stir at 60 r / min for 2 minutes at 20°C; then stir at 120 r / min for 2 minutes until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new thin-spray material for roadways.

[0040] Example 2 A method for preparing a novel thin-film sprayed material for mine roadways based on the utilization of mine solid waste includes the following steps: The following steps were taken: the mass ratio of gold tailings to P.O42.5 grade ordinary Portland cement was 3:7; the dosage of 3mm long polyvinyl alcohol fiber was 0.3% of the total mass of gold tailings and cement; the dosage of hydroxypropyl methylcellulose with a viscosity of 200000mPa·s was 0.1% of the total mass of gold tailings and cement; and the dosage of cement accelerator was 8% of the total mass of gold tailings and cement. Gold tailings with a particle size of 0 < ≤ 70μm, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose, and cement accelerator were accurately weighed and dry-mixed at 65r / min for 1.5min to initially mix the materials. Then, the materials were dry-mixed at 125r / min for 1.5min until uniformly mixed to obtain a homogeneous dry-mixed mixture. Based on a water-cement ratio of 0.45, calculate and measure the water. Then, weigh out the following ingredients according to the following dosages: styrene-butadiene emulsion (SBE) at 10% of the total mass of tailings and cement, polycarboxylate superplasticizer at 0.5% of the total mass of tailings and cement, dodecyl alcohol ester film-forming agent at 1% of the total mass of tailings and cement, and KH550 silane coupling agent at 1% of the total mass of tailings and cement. Stir at 125 r / min for 1.5 min to uniformly disperse the mixture. After slowly and evenly pouring the mixture into the dry mixture, stir at 65 r / min for 2.5 min at 21°C; then stir at 125 r / min for 2.5 min until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new thin-spray material for roadways.

[0041] Example 3 A method for preparing a novel thin-film sprayed material for mine roadways based on the utilization of mine solid waste includes the following steps: The following steps were taken: the mass ratio of gold tailings to P.O42.5 grade ordinary Portland cement was 3:7; the dosage of polyvinyl alcohol fiber with a length of 3 mm was 0.3% of the total mass of gold tailings and cement; the dosage of hydroxypropyl methylcellulose with a viscosity of 200000 mPa·s was 0.1% of the total mass of gold tailings and cement; and the dosage of cement accelerator was 8% of the total mass of gold tailings and cement. Gold tailings with a particle size of 0 < ≤ 70 μm, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose and cement accelerator were accurately weighed and dry-mixed at 55 r / min for 1 min to initially mix the materials; then dry-mixed at 115 r / min for 1 min to obtain a uniform dry-mixed mixture. Based on a water-cement ratio of 0.45, calculate and measure the water. Then, weigh out the following: styrene-butadiene emulsion (SBE) at 10% of the total mass of tailings and cement; polycarboxylate superplasticizer at 0.5% of the total mass of tailings and cement; dodecyl alcohol ester film-forming agent at 1% of the total mass of tailings and cement; and KH550 silane coupling agent at 1% of the total mass of tailings and cement. Stir at 115 r / min for 1 min to uniformly disperse the mixture. After slowly and evenly pouring the mixture into the dry mixture, stir at 55 r / min for 3 minutes at 19°C; then stir at 115 r / min for 3 minutes until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new thin-spray material for roadways.

[0042] Example 4 The difference between Example 4 and Example 1 is that the alkali-free liquid cement accelerator is replaced with a low-alkali liquid cement accelerator.

[0043] A method for preparing a novel thin-film sprayed material for mine roadways based on the utilization of mine solid waste includes the following steps: The following steps were taken: the mass ratio of gold tailings to P.O42.5 grade ordinary Portland cement was 3:7; the dosage of 3mm long polyvinyl alcohol fiber was 0.3% of the total mass of gold tailings and cement; the dosage of hydroxypropyl methylcellulose with a viscosity of 200000mPa·s was 0.1% of the total mass of gold tailings and cement; and the dosage of cement accelerator was 8% of the total mass of gold tailings and cement. Gold tailings with a particle size of 0 < ≤ 70μm, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose and cement accelerator were accurately weighed and dry-mixed at 60r / min for 1min to initially mix the materials. Then, the materials were dry-mixed at 120r / min for 2min until a uniform dry mixture was obtained. Based on a water-cement ratio of 0.45, calculate and measure the water. Then, weigh out the following: styrene-butadiene emulsion (SBE) at 10% of the total mass of tailings and cement; polycarboxylate superplasticizer at 0.5% of the total mass of tailings and cement; dodecyl alcohol ester film-forming agent at 1% of the total mass of tailings and cement; and KH550 silane coupling agent at 1% of the total mass of tailings and cement. Stir at 120 r / min for 2 min to uniformly disperse the mixture. After slowly and evenly pouring the mixture into the dry mixture, stir at 60 r / min for 2 minutes at 20°C; then stir at 120 r / min for 2 minutes until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new thin-spray material for roadways.

[0044] Comparative Example 1 Comparative Example 1 shows the preparation of traditional sprayed concrete.

[0045] All of the above Examples 1 to 4 can prepare new thin-film shotcrete materials for roadways. The effectiveness of the new thin-film shotcrete material prepared in Example 1 is now verified by comparing it with the traditional shotcrete prepared in Comparative Example 1 and the materials prepared in Comparative Examples 2 to 9.

[0046] Experimental verification (1) Material cost The cost and performance of the new thin-film shotcrete material for roadways prepared in Example 1 were compared with those of the traditional shotcrete prepared in Comparative Example 1. Figure 1 As shown, the unit area cost of the new thin-film shotcrete material prepared in Example 1 is 56 yuan, while the unit area cost of traditional shotcrete is 96 yuan. This not only achieves effective control of material costs but also promotes the large-scale application of this technology in mine support. Detailed data are shown in Table 1.

[0047] Table 1. Comparison of cost and performance advantages between new thin-film shotcrete materials and traditional shotcrete in roadways. (2) Mechanical properties ① Compressive strength Figure 2 The images show the compressive strength test results of the new thin-film shotcrete material prepared in Example 1 of this invention and the conventional shotcrete prepared in Comparative Example 1. Figure 2 It can be seen that the new thin-film shotcrete material in the tunnel reaches 5.0MPa, 20.5MPa and 29.6MPa at 3 days, 7 days and 28 days respectively, which is about 11.1%, 53.2% and 20.3% higher than that of traditional shotcrete.

[0048] ② Flexural strength Figure 3 The figures show the flexural strength test results of the new thin-film shotcrete material for roadways prepared in Example 1 of the present invention and the conventional shotcrete prepared in Comparative Example 1. Figure 3 It can be seen that the new thin-film shotcrete material for roadways also performed outstandingly, reaching 1.1MPa, 4.1MPa and 6.6MPa at 3 days, 7 days and 28 days respectively, which are 120%, 241.7% and 8.2% higher than traditional shotcrete.

[0049] This fully demonstrates the comprehensive superiority of the material of the present invention in terms of early strength development and long-term mechanical properties, and it is especially suitable for thin-shot shotcrete support scenarios in mines where high early strength and toughness are required.

[0050] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a novel thin-film spraying material for mine roadways based on the utilization of mine solid waste, characterized in that, Includes the following steps: Gold tailings, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose, and cement accelerator were mixed evenly to obtain a dry-mixed mixture. The mass ratio of gold tailings to cement was 3:7, and the dosages of polyvinyl alcohol fiber, hydroxypropyl methylcellulose, and cement accelerator were 0.3%, 0.1%, and 8% of the total mass of gold tailings and cement, respectively. Add water at a water-cement ratio of 0.45, then add styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent to the water in sequence, and disperse evenly to obtain a mixture. The dosages of styrene-butadiene emulsion, polycarboxylate superplasticizer, dodecyl alcohol film-forming agent, and KH550 silane coupling agent are 10%, 0.5%, 1%, and 1% of the total mass of gold tailings and cement, respectively. After pouring the liquid into the dry mixture, heat and stir until the mixture has a uniform color, uniform texture, and no dry powder lumps or bleeding, thus obtaining a new material for thin spraying in tunnels.

2. The method for preparing a new roadway thin-layer spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The particle size of the gold tailings is set to 0 < particle size ≤ 70 μm, and the length of the polyvinyl alcohol fiber is 3 mm.

3. The method for preparing a new roadway thin-film spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The cement accelerator is an alkali-free or low-alkali liquid accelerator, and the viscosity of the hydroxypropyl methylcellulose is 200,000 mPa.

4. The method for preparing a new roadway thin-film spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The mixing steps for preparing the dry mixture are as follows: the gold tailings, cement, polyvinyl alcohol fiber, hydroxypropyl methylcellulose and cement quick-setting agent are first dry mixed at 55r / min~65r / min for 1min~2min to initially mix the materials, and then dry mixed at a mixing speed of 115r / min~125r / min for 1min~2min.

5. The method for preparing a new roadway thin-layer spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The stirring speed during the preparation of the mixture is 115 r / min to 125 r / min, and the stirring time is 1 min to 2 min.

6. The method for preparing a new roadway thin-film spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The heating temperature for preparing the new thin-spray material for roadways is 19℃~21℃. When preparing the new thin-spray material for roadways, first stir at a stirring speed of 55r / min~65r / min for 2min~3min; then stir at a stirring speed of 115r / min~125r / min for 2min~3min.

7. The method for preparing a new roadway thin-film spraying material based on the utilization of mine solid waste according to claim 1, characterized in that, The cement accelerator is an alkali-free accelerator or a low-alkali accelerator.

8. The new roadway thin-spray material prepared by the method for preparing new roadway thin-spray material based on the utilization of mine solid waste according to any one of claims 1 to 7.

9. The thin-spraying process of the new roadway thin-spraying material according to claim 8, characterized in that, This thin-spray process can be either a manual spray gun thin-spray process or a robotic arm spray gun thin-spray process. When using the manual spray gun thin spraying process, the new roadway thin spraying material is prepared according to the preparation method of the new roadway thin spraying material based on the utilization of mine solid waste given in Examples 1 to 9, and the new roadway thin spraying material is pumped to the manual spray gun. The thin spraying material is sprayed from top to bottom in a layered and segmented manner. After spraying, it is trimmed and watered for curing before final setting to form a spray layer. When using the robotic arm spray gun thin spraying process, the new thin spraying material for roadways based on the utilization of mine solid waste is prepared according to the preparation method of the new thin spraying material for roadways according to Examples 1-9. The cement accelerator is not added temporarily. The prepared thin spraying material is pumped to the nozzle of the robotic arm spray gun, and the cement accelerator is added at the nozzle of the robotic arm spray gun. After the thin spraying material is initially sprayed in layers, it is sprayed again. After spraying, the surface is repaired and moisturized to form a spray layer.

10. The application of the new thin-layer spraying material for mine roadways, chambers, working faces and slopes as described in claim 8 for surface sealing, weathering prevention, air leakage prevention, reinforcement and support.

Images