Mining thin-spraying flexible support material and preparation method thereof

Abstract

The invention belongs to the technical field of mining support, and particularly relates to a mining thin-spraying flexible support material and a preparation method thereof. The flame-retardant coating is formed by mixing a component A and a component B. The component A comprises the following components in parts by weight: 50-70 parts of RADA16 peptide modified acrylate emulsion, 15-35 parts of deionized water, 10-15 parts of an aluminum hydroxide flame retardant and 0.5-1 part of a polyether ester defoaming agent; the component B is prepared from 40 to 60 parts of Portland cement, 25 to 35 parts of heavy calcium carbonate, 5 to 15 parts of nano silicon powder, 7 to 12 parts of beta-1, 3-glucan coated iron tailing micro powder and 1 to 3 parts of polypropylene fiber. Wherein the RADA16 peptide modified acrylate emulsion improves the cohesiveness of the cement and surrounding rock through electrostatic adsorption; and beta-1, 3-glucan is adopted to coat the iron tailing micro powder to fill pores, so that the compactness is improved, and the cracking of a cement matrix is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of mine support, and in particular relates to a mine thin-spray flexible support material and a preparation method thereof. Background Art

[0002] The rock in mine tunnels has poor mechanical properties and instability. The sandstone, shale, and mudstone within the tunnels are susceptible to weathering and softening, even experiencing mudification, disintegration, and expansion. my country's mine tunnels primarily utilize anchor-shotcrete support. However, anchor rods, trays, and metal meshes are susceptible to rust in the humid underground environment, leading to loosening, breakage, and loss of prestress, severely weakening the support effectiveness. Furthermore, shotcrete, as a brittle material, suffers from shortcomings such as low tensile stress resistance, high rebound rate, poor construction environment, severe dust pollution, and easy shedding of the shotcrete layer, limiting the development of this technology.

[0003] A new type of flexible, thin-film sprayed material for mining is applied to the surrounding rock surface by spraying. After drying and solidifying, it forms a flexible spray layer several millimeters thick. Compared to shotcrete, this material offers significant advantages in terms of reduced construction workload, reduced material transportation, and greater adaptability to deformation. During construction, no heat or VOCs are released, meeting non-toxic and environmental standards, and the spraying process is dust-free. The flexible lining tightly bonds to the rock mass, enabling it to assume a load-bearing role even at an early stage of surrounding rock deformation. However, the new type of flexible, thin-film sprayed material for mining still suffers from issues such as low adhesion and susceptibility to cracking. Summary of the Invention

[0004] The purpose of the present invention is to provide a thin-shot sprayed flexible supporting material for mining and a preparation method thereof to solve the above-mentioned technical problems.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention is: A thin shotcrete flexible support material for mining, composed of component A and component B, calculated by weight: Component A includes: 50-70 parts of RADA16 peptide-modified acrylic emulsion, 15-35 parts of deionized water, 10-15 parts of aluminum hydroxide flame retardant, and 0.5-1 part of polyether ester defoamer; Component B includes: 40-60 parts of Portland cement, 25-35 parts of heavy calcium carbonate, 5-15 parts of nano-silicon powder, 7-12 parts of β-1,3-glucan coated iron tailings powder, and 1-3 parts of polypropylene fiber.

[0006] The present invention also provides a method for preparing a thin-shot sprayed flexible support material for mining, comprising the following steps: S1, coating the iron tailings fine powder with a β-1,3-glucan solution to obtain β-1,3-glucan-coated iron tailings fine powder; S2. Mixing acrylate monomer, reactive emulsifier DNS-86, compound emulsifier Tween-80 with deionized water, and shearing at 2000 rpm for 15 minutes to form an acrylate pre-emulsion; dissolving ammonium persulfate in deionized water and stirring for 5 minutes to obtain an initiator solution; taking 10% of the acrylate pre-emulsion and the initiator solution respectively, mixing the two, passing nitrogen gas, heating to 80°C, reacting for 30 minutes, and then slowly adding the remaining acrylate pre-emulsion and initiator solution dropwise to the mixture within 2 hours, keeping the temperature at 80°C for 1 hour; cooling to 40°C, adjusting the pH value to 7-8 with ammonia water, and filtering to obtain an acrylate emulsion; S3. Add RADA16 peptide powder to N,N-dimethylformamide, sonicate for 30 minutes, and filter to obtain a RADA16 peptide solution; add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reagent and N-hydroxysuccinimide reagent to the RADA16 peptide solution, and stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; slowly add the activated peptide solution dropwise to the acrylate emulsion, adjust the pH value to 7.5 with 0.1 mol / L sodium hydroxide, and stir and react at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, dialyze the reaction solution with deionized water to obtain a RADA16 peptide-modified acrylate emulsion; S4. Mix the RADA16 peptide-modified acrylate emulsion with deionized water at 500-800 rpm for 5 minutes, slowly add the aluminum hydroxide flame retardant while stirring, increase the speed to 1000-1200 rpm after the addition, and disperse at high speed for 10 minutes, then reduce the speed to 600-800 rpm and slowly add the polyether ester defoamer, and continue stirring for 5 minutes to obtain a mixed component A; S5. Mixing silicate cement, heavy calcium carbonate, nano-silica powder, and β-1,3-glucan-coated iron tailings powder at 15-20 rpm for 10 minutes, slowly and evenly adding polypropylene fiber thereto, and continuing mixing for 5 minutes to obtain a mixed component B; S6. Dry-stir component B at 20-30 rpm for 1-2 minutes to loosen the dry material; under continuous low-speed stirring, add component A evenly and continuously within 5-7 minutes. After adding component A, increase the speed to 30-40 rpm and stir for 20 minutes; finally, adjust the speed to 15-20 rpm and stir for 5 minutes to obtain the thin-sprayed flexible support material for mining.

[0007] As a further improvement, in step S1, the preparation of β-1,3-glucan-coated iron tailings micropowder is specifically as follows: the iron tailings are dried and ground into micropowder to obtain iron tailings micropowder; the β-1,3-glucan powder is dissolved in deionized water to obtain a β-1,3-glucan solution; and the β-1,3-glucan solution is coated on the iron tailings micropowder using a fluidized bed to obtain β-1,3-glucan-coated iron tailings micropowder.

[0008] As a further improvement, in step S1, the weight ratio of the β-1,3-glucan solution to the iron tailings powder is 1:8.

[0009] As a further improvement, in step S2, the acrylic acid ester monomer comprises butyl acrylate, methyl methacrylate and acrylic acid in a weight ratio of 60:40:5.

[0010] As a further improvement, in step S2, the weight of the ammonium persulfate is 0.67% of the total weight of the acrylic acid ester monomers.

[0011] As a further improvement, in step S3, the weight ratio of RADA16 peptide powder to N,N-dimethylformamide is 1:13.

[0012] As a further improvement, in step S3, the weight ratio of the RADA16 peptide solution, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reagent, N-hydroxysuccinimide reagent and acrylate emulsion is 1:1.5:0.75:16.3.

[0013] As a further improvement, the concentration of the β-1,3-glucan solution is 0.1 g / mL.

[0014] Due to the adoption of the above technical solution, the present invention has the following beneficial effects: 1. This invention provides a thin-shot flexible support material for mining and its preparation method. The material improves the adhesion between Portland cement and surrounding rock by modifying an acrylate emulsion with RADA16 peptide. The acrylate emulsion improves the support material's flexibility, and the RADA16 peptide hydrogel exhibits adjustable mechanical stability, good compatibility, and elasticity similar to that of natural tissue. The RADA16 peptide forms nanofibers with a β-pleated structure in deionized water. These fibers penetrate the cement hydration product (CSH gel) and the acrylate emulsion, forming an interpenetrating structure: the CSH gel provides a rigid framework, the acrylate emulsion fills pores and forms a film to inhibit microcrack propagation, and the RADA16 fibers bridge the cement hydration product and acrylate emulsion through hydrogen bonds.

[0015] 2. The arginine residues in the RADA16 peptide carry a positive charge, which reacts with the negatively charged silicate [SiO4] on the surface of cement particles. 4-Bonding; enhance the bonding between silicate cement and surrounding rock through electrostatic adsorption.

[0016] 3. The present invention improves the crack resistance of cement-based by adding β-1,3-glucan to coat the iron tailings powder. The long chain structure of β-1,3-glucan obtained by natural biological fermentation can bridge micro cracks. The β-1,3-glucan coated on the surface of the iron tailings powder in component B has hydroxyl groups that react with Ca in the cement hydration product. 2+ The formation of coordination bonds makes the cement hydration products more densely arranged, reduces the porosity, and further enhances the overall strength of the cement-based material.

[0017] 4. The hydrophilicity of β-1,3-glucan regulates the evaporation rate of water, preventing cracks caused by excessive evaporation of water during the drying and solidification process of the sprayed material; at the same time, its water retention effect optimizes the cement hydration process, avoiding stress concentration caused by local uneven hydration.

[0018] 5. The iron tailings powder particles are extremely fine and can fill the capillary pores in the cement matrix and the gaps between the cement matrix and the surrounding rock, thereby reducing the porosity and increasing the density. After mechanical grinding, its specific surface area reaches or exceeds 400m 2 / kg, significantly increasing surface energy, lattice distortion, and amorphous content, which helps promote chemical bonding with cement hydration products. Micropowder particles form a dense layer at the cement-rock interface, reducing the Ca / Si ratio at the interface and enhancing mechanical and chemical bonding strength with the surrounding rock. DETAILED DESCRIPTION

[0019] The technical solutions of the present invention will be described clearly and completely below in conjunction with specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. For those whose specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer shall be followed. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially. The fluidized bed used is the 0002-0010 fluidized bed of Fluid Air Company.

[0020] Example 1: A method for preparing a thin-shot sprayed flexible support material for mining, comprising the following steps: S1. Dry the iron tailings sand and gravel at 105℃, put them into a planetary ball mill, and mill them at 350rpm for 2h. After the discharge is sieved through a 325-mesh sieve, the specific surface area is ≥400m 2 / kg of iron tailings fine powder.

[0021] S2. Take 1 part of β-1,3-glucan powder (purity ≥90%) and add it to 10 parts of deionized water. Stir at 140 rpm for 60 min and filter through a 5 μm filter membrane to obtain a β-1,3-glucan solution. Add 8 parts of iron tailings powder into the fluidized bed hopper, start the fan, introduce nitrogen, fix the fluidization wind speed at 0.5 m / s, maintain the fluidization number at 2.2, and observe the fluidization state: the particles show uniform vortex motion and the bed pressure drop is stable. Pour 1 part of β-1,3-glucan solution into the fluidized bed spray device and start heating. After the inlet air temperature stabilized at 80°C, the liquid spraying was started with a spray rate of 10.28g / min and an atomization pressure of 1bar. The exhaust temperature was monitored in real time and was 10~20°C lower than the inlet air temperature, indicating that the evaporation was normal. Samples were taken every 10 minutes and the moisture content of the particles was quickly determined. The moisture content of the particles was ≤5%. After 90 minutes, the liquid spraying was ended and the inlet air temperature was lowered to 50°C. The fluidization was maintained for 15 minutes to evaporate the residual moisture. Before shutting down, the particles were cooled with cold air at 25°C for 5 minutes to obtain β-1,3-glucan-coated iron tailings powder.

[0022] S3. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0023] S4. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0024] S5. Add 1 part of RADA16 peptide powder to 13 parts of N,N-dimethylformamide (DMF), sonicate for 30 minutes to completely dissolve the powder, and filter to obtain a RADA16 peptide solution.

[0025] S6. Add 1.5 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) reagent and 0.75 parts of N-hydroxysuccinimide (NHS) reagent to 1 part of RADA16 peptide solution, stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; add the activated peptide solution dropwise to 16.3 parts of acrylate emulsion at a rate of 1 mL / min, adjust the pH to 7.5 with 0.1 mol / L sodium hydroxide, and stir the reaction at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, place the reaction solution in a dialysis bag with a molecular weight cutoff of 3500 Da, and dialyze with deionized water to remove small molecule solvents and cross-linking agents, retain large molecular organic matter, change the water every 8 hours, and after dialysis for 48 hours, obtain a RADA16 peptide-modified acrylate emulsion.

[0026] S7. Add 70 parts of RADA16 peptide-modified acrylic emulsion and 35 parts of deionized water into a dispersion kettle, mix at 800 rpm for 5 minutes, and preliminarily mix the emulsion and water. Slowly add 15 parts of aluminum hydroxide flame retardant while stirring. After adding, increase the speed to 1200 rpm and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed. Reduce the speed to 800 rpm and slowly add 1 part of polyether ester defoamer. Continue stirring for 5 minutes to evenly mix all liquid components to obtain a mixed component A.

[0027] S8. Add 60 parts of Portland cement, 35 parts of heavy calcium carbonate, 15 parts of nano-silica powder and 12 parts of β-1,3-glucan-coated iron tailings powder in sequence into a V-type mixer set at 20 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and there is no agglomeration. Then, slowly and evenly add 3 parts of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0028] S9. Add all the mixed dry materials of component B into the mixer and stir at 30 rpm for 2 minutes to loosen the dry materials. Pour the prepared component A into the mixer evenly and continuously within 7 minutes under continuous low-speed stirring. After component A is added, increase the mixer speed to 40 rpm and stir for 20 minutes. Closely observe the fluidity, viscosity, uniformity and bubbles of the slurry. If the slurry is normal, adjust the speed to 20 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0029] Example 2: A method for preparing a thin-shot sprayed flexible support material for mining, comprising the following steps: S1. Dry the iron tailings sand and gravel at 105℃, put them into a planetary ball mill, and mill them at 350rpm for 2h. After the discharge is sieved through a 325-mesh sieve, the specific surface area is ≥400m 2 / kg of iron tailings fine powder.

[0030] S2. Take 1 part of β-1,3-glucan powder (purity ≥90%) and add it to 10 parts of deionized water. Stir at 140 rpm for 60 min and filter through a 5 μm filter membrane to obtain a β-1,3-glucan solution. Add 8 parts of iron tailings powder into the fluidized bed hopper, start the fan, introduce nitrogen, fix the fluidization wind speed at 0.5 m / s, maintain the fluidization number at 2.2, and observe the fluidization state: the particles show uniform vortex motion and the bed pressure drop is stable. Pour 1 part of β-1,3-glucan solution into the fluidized bed spray device and start heating. After the inlet air temperature stabilized at 80°C, the liquid spraying was started with a spray rate of 10.28g / min and an atomization pressure of 1bar. The exhaust temperature was monitored in real time and was 10~20°C lower than the inlet air temperature, indicating that the evaporation was normal. Samples were taken every 10 minutes and the moisture content of the particles was quickly determined. The moisture content of the particles was ≤5%. After 90 minutes, the liquid spraying was ended and the inlet air temperature was lowered to 50°C. The fluidization was maintained for 15 minutes to evaporate the residual moisture. Before shutting down, the particles were cooled with cold air at 25°C for 5 minutes to obtain β-1,3-glucan-coated iron tailings powder.

[0031] S3. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0032] S4. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0033] S5. Add 1 part of RADA16 peptide powder to 13 parts of N,N-dimethylformamide (DMF), sonicate for 30 minutes to completely dissolve the powder, and filter to obtain a RADA16 peptide solution.

[0034] S6. Add 1.5 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) reagent and 0.75 parts of N-hydroxysuccinimide (NHS) reagent to 1 part of RADA16 peptide solution, stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; add the activated peptide solution dropwise to 16.3 parts of acrylate emulsion at a rate of 1 mL / min, adjust the pH to 7.5 with 0.1 mol / L sodium hydroxide, and stir the reaction at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, place the reaction solution in a dialysis bag with a molecular weight cutoff of 3500 Da, and dialyze with deionized water to remove small molecule solvents and cross-linking agents, retain large molecular organic matter, change the water every 8 hours, and after dialysis for 48 hours, obtain a RADA16 peptide-modified acrylate emulsion.

[0035] S7. Add 50 parts of RADA16 peptide-modified acrylic emulsion and 15 parts of deionized water into a dispersion kettle, mix at 500 rpm for 5 minutes to ensure that the emulsion and water are initially mixed evenly; slowly add 10 parts of aluminum hydroxide flame retardant while stirring, increase the speed to 1000 rpm after adding, and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed; reduce the speed to 600 rpm and slowly add 0.5 parts of polyether ester defoamer, continue stirring for 5 minutes to evenly mix all liquid components to obtain a mixed component A.

[0036] S8. Add 40 parts of Portland cement, 25 parts of heavy calcium carbonate, 5 parts of nano-silica powder and 7 parts of β-1,3-glucan-coated iron tailings powder in sequence into a V-type mixer set at 15 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and there is no agglomeration. Then slowly and evenly add 1 part of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0037] S9. Add all the mixed B component dry materials into the mixer and stir at 20 rpm for 1 minute to loosen the dry materials; under continuous low-speed stirring, pour the prepared A component into the mixer evenly and continuously within 5 minutes. After the A component is added, increase the mixer speed to 30 rpm and stir for 20 minutes; closely observe the fluidity, viscosity, uniformity and bubble conditions of the slurry. If the slurry is normal, adjust the speed to 15 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0038] Example 3: A method for preparing a thin-shot sprayed flexible support material for mining, comprising the following steps: S1. Dry the iron tailings sand and gravel at 105℃, put them into a planetary ball mill, and mill them at 350rpm for 2h. After the discharge is sieved through a 325-mesh sieve, the specific surface area is ≥400m 2 / kg of iron tailings fine powder.

[0039] S2. Take 1 part of β-1,3-glucan powder (purity ≥90%) and add it to 10 parts of deionized water. Stir at 140 rpm for 60 min and filter through a 5 μm filter membrane to obtain a β-1,3-glucan solution. Add 8 parts of iron tailings powder into the fluidized bed hopper, start the fan, introduce nitrogen, fix the fluidization wind speed at 0.5 m / s, maintain the fluidization number at 2.2, and observe the fluidization state: the particles show uniform vortex motion and the bed pressure drop is stable. Pour 1 part of β-1,3-glucan solution into the fluidized bed spray device and start heating. After the inlet air temperature stabilized at 80°C, the liquid spraying was started with a spray rate of 10.28g / min and an atomization pressure of 1bar. The exhaust temperature was monitored in real time and was 10~20°C lower than the inlet air temperature, indicating that the evaporation was normal. Samples were taken every 10 minutes and the moisture content of the particles was quickly determined. The moisture content of the particles was ≤5%. After 90 minutes, the liquid spraying was ended and the inlet air temperature was lowered to 50°C. The fluidization was maintained for 15 minutes to evaporate the residual moisture. Before shutting down, the particles were cooled with cold air at 25°C for 5 minutes to obtain β-1,3-glucan-coated iron tailings powder.

[0040] S3. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0041] S4. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0042] S5. Add 1 part of RADA16 peptide powder to 13 parts of N,N-dimethylformamide (DMF), sonicate for 30 minutes to completely dissolve the powder, and filter to obtain a RADA16 peptide solution.

[0043] S6. Add 1.5 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) reagent and 0.75 parts of N-hydroxysuccinimide (NHS) reagent to 1 part of RADA16 peptide solution, stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; add the activated peptide solution dropwise to 16.3 parts of acrylate emulsion at a rate of 1 mL / min, adjust the pH to 7.5 with 0.1 mol / L sodium hydroxide, and stir the reaction at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, place the reaction solution in a dialysis bag with a molecular weight cutoff of 3500 Da, and dialyze with deionized water to remove small molecule solvents and cross-linking agents, retain large molecular organic matter, change the water every 8 hours, and after dialysis for 48 hours, obtain a RADA16 peptide-modified acrylate emulsion.

[0044] S7. Add 60 parts of RADA16 peptide-modified acrylic emulsion and 25 parts of deionized water into a dispersion kettle and mix at 650 rpm for 5 minutes to ensure that the emulsion and water are initially mixed evenly; slowly add 13 parts of aluminum hydroxide flame retardant while stirring, increase the speed to 1100 rpm after adding, and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed; reduce the speed to 700 rpm and slowly add 0.8 parts of polyether ester defoamer, continue stirring for 5 minutes to ensure that all liquid components are evenly mixed to obtain a mixed component A.

[0045] S8. Add 50 parts of Portland cement, 30 parts of heavy calcium carbonate, 10 parts of nano-silica powder and 10 parts of β-1,3-glucan-coated iron tailings powder in sequence into a V-type mixer set at 17 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and there is no agglomeration. Then slowly and evenly add 2 parts of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0046] S9. Add all the mixed dry materials of component B into the mixer and stir at 25 rpm for 1.5 minutes to loosen the dry materials. Pour the prepared component A into the mixer evenly and continuously within 6 minutes under continuous low-speed stirring. After component A is added, increase the mixer speed to 35 rpm and stir for 20 minutes. Closely observe the fluidity, viscosity, uniformity and bubbles of the slurry. If the slurry is normal, adjust the speed to 17 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0047] Comparative Example 1: Compared with Example 1, Comparative Example 1 does not add β-1,3-glucan coated iron tailings powder to the cement base, and the specific method is as follows: S1. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0048] S2. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0049] S3. Add 1 part of RADA16 peptide powder to 13 parts of N,N-dimethylformamide (DMF), sonicate for 30 minutes to completely dissolve the powder, and filter to obtain a RADA16 peptide solution.

[0050] S4. Add 1.5 parts of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) reagent and 0.75 parts of N-hydroxysuccinimide (NHS) reagent to 1 part of RADA16 peptide solution, stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; add the activated peptide solution dropwise to 16.3 parts of acrylate emulsion at a rate of 1 mL / min, adjust the pH to 7.5 with 0.1 mol / L sodium hydroxide, and stir the reaction at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, place the reaction solution in a dialysis bag with a molecular weight cutoff of 3500 Da, dialyze with deionized water to remove small molecule solvents and cross-linking agents, and retain large molecular organic matter. Change the water every 8 hours. After dialysis for 48 hours, a RADA16 peptide-modified acrylate emulsion is obtained.

[0051] S5. Add 70 parts of RADA16 peptide-modified acrylic emulsion and 35 parts of deionized water into a dispersion kettle, mix at 800 rpm for 5 minutes, and preliminarily mix the emulsion and water. Slowly add 15 parts of aluminum hydroxide flame retardant while stirring. After adding, increase the speed to 1200 rpm and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed. Reduce the speed to 800 rpm and slowly add 1 part of polyether ester defoamer. Continue stirring for 5 minutes to evenly mix all liquid components to obtain a mixed component A.

[0052] S6. Add 60 parts of Portland cement, 35 parts of heavy calcium carbonate, and 15 parts of nano-silicon powder in sequence into a V-type mixer set at 20 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and uniform without agglomeration. Then slowly and evenly add 3 parts of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0053] S7. Add all the mixed dry materials of component B into the mixer and stir at 30 rpm for 2 minutes to loosen the dry materials. Pour the prepared component A into the mixer evenly and continuously within 7 minutes under continuous low-speed stirring. After component A is added, increase the mixer speed to 40 rpm and stir for 20 minutes. Closely observe the fluidity, viscosity, uniformity and bubbles of the slurry. If the slurry is normal, adjust the speed to 20 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0054] Comparative Example 2: Compared with Example 1, Comparative Example 2 did not use RADA16 peptide to modify the acrylic ester emulsion, and the specific method was as follows: S1. Dry the iron tailings sand and gravel at 105℃, put them into a planetary ball mill, and mill them at 350rpm for 2h. After the discharge is sieved through a 325-mesh sieve, the specific surface area is ≥400m 2 / kg of iron tailings fine powder.

[0055] S2. Take 1 part of β-1,3-glucan powder (purity ≥90%) and add it to 10 parts of deionized water. Stir at 140 rpm for 60 min and filter through a 5 μm filter membrane to obtain a β-1,3-glucan solution. Add 8 parts of iron tailings powder into the fluidized bed hopper, start the fan, introduce nitrogen, fix the fluidization wind speed at 0.5 m / s, maintain the fluidization number at 2.2, and observe the fluidization state: the particles show uniform vortex motion and the bed pressure drop is stable. Pour 1 part of β-1,3-glucan solution into the fluidized bed spray device and start heating. After the inlet air temperature stabilized at 80°C, the liquid spraying was started with a spray rate of 10.28g / min and an atomization pressure of 1bar. The exhaust temperature was monitored in real time and was 10~20°C lower than the inlet air temperature, indicating that the evaporation was normal. Samples were taken every 10 minutes and the moisture content of the particles was quickly determined. The moisture content of the particles was ≤5%. After 90 minutes, the liquid spraying was ended and the inlet air temperature was lowered to 50°C. The fluidization was maintained for 15 minutes to evaporate the residual moisture. Before shutting down, the particles were cooled with cold air at 25°C for 5 minutes to obtain β-1,3-glucan-coated iron tailings powder.

[0056] S3. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0057] S4. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0058] S5. Add 70 parts of acrylic emulsion and 35 parts of deionized water into a dispersion kettle, mix at 800 rpm for 5 minutes, and preliminarily mix the emulsion and water. Slowly add 15 parts of aluminum hydroxide flame retardant while stirring. After adding, increase the speed to 1200 rpm and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed. Reduce the speed to 800 rpm and slowly add 1 part of polyether ester defoamer. Continue stirring for 5 minutes to evenly mix all liquid components to obtain a mixed component A.

[0059] S6. Add 60 parts of Portland cement, 35 parts of heavy calcium carbonate, 15 parts of nano-silica powder and 12 parts of β-1,3-glucan-coated iron tailings powder in sequence into a V-type mixer set at 20 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and there is no agglomeration. Then, slowly and evenly add 3 parts of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0060] S7. Add all the mixed dry materials of component B into the mixer and stir at 30 rpm for 2 minutes to loosen the dry materials. Pour the prepared component A into the mixer evenly and continuously within 7 minutes under continuous low-speed stirring. After component A is added, increase the mixer speed to 40 rpm and stir for 20 minutes. Closely observe the fluidity, viscosity, uniformity and bubbles of the slurry. If the slurry is normal, adjust the speed to 20 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0061] Comparative Example 3: Compared with Example 1, Comparative Example 3 neither added β-1,3-glucan-coated iron tailings powder to the cement base nor used RADA16 peptide to modify the acrylate emulsion. The specific method is as follows: S1. Mix 60 parts of butyl acrylate (BA), 40 parts of methyl methacrylate (MMA), 5 parts of acrylic acid (AA), 1 part of reactive emulsifier DNS-86, 1 part of compound emulsifier Tween-80 and 100 parts of deionized water, and shear for 15 minutes in a high-speed dispersing emulsifier at 2000 rpm to form an acrylate pre-emulsion; dissolve 0.7 parts of ammonium persulfate (APS) in 20 parts of deionized water and stir for 5 minutes to obtain an ammonium persulfate solution, i.e., an initiator solution.

[0062] S2. Take 10% of the acrylate pre-emulsion and initiator solution respectively, add them to the reactor, introduce nitrogen, heat to 80°C, react for 30 minutes to form a seed emulsion; slowly add the remaining acrylate pre-emulsion and initiator solution to the reactor at the same time, complete the addition within 2 hours, keep the temperature at 80°C and react for 1 hour; cool to 40°C, adjust the pH value to 7-8 with ammonia water, and filter to obtain the acrylate emulsion.

[0063] S3. Add 70 parts of acrylic emulsion and 35 parts of deionized water into a dispersion kettle and mix at 800 rpm for 5 minutes to ensure that the emulsion and water are initially mixed evenly; slowly add 15 parts of aluminum hydroxide flame retardant while stirring, increase the speed to 1200 rpm after adding, and disperse at high speed for 10 minutes to ensure that the aluminum hydroxide is fully dispersed; reduce the speed to 800 rpm and slowly add 1 part of polyether ester defoamer, continue stirring for 5 minutes to ensure that all liquid components are evenly mixed to obtain a mixed component A.

[0064] S4. Add 60 parts of Portland cement, 35 parts of heavy calcium carbonate, and 15 parts of nano-silicon powder in sequence into a V-type mixer set at 20 rpm and mix for 10 minutes to ensure that the dry powder is fully mixed and there is no agglomeration. Then slowly and evenly add 3 parts of polypropylene fiber into the mixer and continue mixing for 5 minutes to fully disperse the fiber to obtain a mixed B component.

[0065] S5. Add all the mixed B component dry materials into the mixer and stir at 30 rpm for 2 minutes to loosen the dry materials; under continuous low-speed stirring, pour the prepared A component into the mixer evenly and continuously within 7 minutes. After the addition of A component is completed, increase the mixer speed to 40 rpm and stir for 20 minutes; closely observe the fluidity, viscosity, uniformity and bubble conditions of the slurry. If the slurry condition is normal, adjust the speed to 20 rpm and stir for 5 minutes to make the slurry more uniform and expel large bubbles to obtain the thin-sprayed flexible support material for mining.

[0066] The following tests were performed on the thin-sprayed flexible support materials for mining prepared in Examples 1 to 3 and Comparative Examples 1 to 3.

[0067] The tensile strength, elongation at break and bonding strength of the thin-sprayed flexible support materials for mining used in Examples 1 to 3 and Comparative Examples 1 to 3 cured for 28 days were measured according to GB / T 16777-2008 “Test methods for building waterproof coatings”.

[0068] According to the anti-cracking test method in GB / T 50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the anti-cracking properties of Examples 1 to 3 and Comparative Examples 1 to 3 were measured.

[0069] The results are shown in Table 1.

[0070] Table 1 Test results of bonding strength, tensile strength, elongation at break and total cracking area per unit area of ​​each group of mine-used thin-shot flexible support materials

[0071] As can be seen from Table 1, the thin-sprayed flexible support materials for mining prepared in Examples 1-3 exhibit superior performance in terms of bonding strength, tensile strength, and elongation at break compared to Comparative Examples 1-3. In particular, Example 1 achieved a bonding strength of 2.2 MPa, a tensile strength of 3.4 MPa, and an elongation at break of 236%. Furthermore, the total cracking area per unit area was minimal, at 22.6 mm² / m², demonstrating excellent bonding and crack resistance.

[0072] Compared with Comparative Example 1, Example 1 added β-1,3-glucan-coated iron tailings powder to the cement base, which significantly improved the tensile strength and elongation at break of the support material and reduced the cracking area, indicating that the modified iron tailings powder can effectively enhance the overall performance of the material.

[0073] Although Comparative Example 2 also used β-1,3-glucan-coated iron tailings powder, its component A did not use RADA16 peptide-modified acrylate emulsion, resulting in lower bond strength and tensile strength than the examples, and a larger crack area. This further demonstrates the effectiveness of RADA16 peptide-modified acrylate emulsion in improving the bonding properties of support materials.

[0074] Comparative Example 3 neither added modified iron tailings powder nor used RADA16 peptide-modified acrylate emulsion. Its performance indicators were the worst, especially the bonding strength and tensile strength were much lower than those in the examples, and the cracking area was the largest, indicating that these two modified components are crucial to improving the comprehensive performance of thin-sprayed flexible support materials for mining.

[0075] In summary, the present invention successfully prepared a thin-sprayed flexible support material for mining with excellent bonding and crack resistance by adding β-1,3-glucan-coated iron tailings powder to cement and using RADA16 peptide-modified acrylate emulsion, providing a new solution for the field of mine support.

[0076] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A thin-sprayed flexible support material for mining, characterized in that: It is composed of component A and component B, in parts by weight, Component A includes: 50~70 parts of RADA16 peptide modified acrylic emulsion, 15~35 parts of deionized water, 10~15 parts of aluminum hydroxide flame retardant, 0.5~1 part of polyetherester defoamer; Component B includes: 40~60 parts of Portland cement, 25~35 parts of heavy calcium, 5~15 parts of nano silicon powder, 7-12 parts of β-1,3-glucan coated iron tailings powder, 1~3 parts of polypropylene fiber.

2. The method for preparing a thin-sprayed flexible support material for mining according to claim 1, characterized in that: S1, coating the iron tailings fine powder with a β-1,3-glucan solution to obtain β-1,3-glucan-coated iron tailings fine powder; S2. Mixing acrylate monomer, reactive emulsifier DNS-86, compound emulsifier Tween-80 with deionized water, and shearing at 2000 rpm for 15 minutes to form an acrylate pre-emulsion; dissolving ammonium persulfate in deionized water and stirring for 5 minutes to obtain an initiator solution; taking 10% of the acrylate pre-emulsion and the initiator solution respectively, mixing the two, passing nitrogen gas, heating to 80°C, reacting for 30 minutes, and then slowly adding the remaining acrylate pre-emulsion and initiator solution dropwise to the mixture within 2 hours, keeping the temperature at 80°C for 1 hour; cooling to 40°C, adjusting the pH value to 7-8 with ammonia water, and filtering to obtain an acrylate emulsion; S3. Add RADA16 peptide powder to N,N-dimethylformamide, sonicate for 30 minutes, and filter to obtain a RADA16 peptide solution; add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reagent and N-hydroxysuccinimide reagent to the RADA16 peptide solution, and stir and activate at 25°C for 30 minutes to obtain an activated peptide solution; slowly add the activated peptide solution dropwise to the acrylate emulsion, adjust the pH value to 7.5 with 0.1 mol / L sodium hydroxide, and stir and react at 40°C and 200 rpm for 2.5 hours. After the reaction is completed, dialyze the reaction solution with deionized water to obtain a RADA16 peptide-modified acrylate emulsion; S4. Mix the RADA16 peptide-modified acrylate emulsion with deionized water at 500-800 rpm for 5 minutes, slowly add the aluminum hydroxide flame retardant while stirring, increase the speed to 1000-1200 rpm after the addition, and disperse at high speed for 10 minutes, then reduce the speed to 600-800 rpm and slowly add the polyether ester defoamer, and continue stirring for 5 minutes to obtain a mixed component A; S5. Mixing silicate cement, heavy calcium carbonate, nano-silica powder, and β-1,3-glucan-coated iron tailings powder at 15-20 rpm for 10 minutes, slowly and evenly adding polypropylene fiber thereto, and continuing mixing for 5 minutes to obtain a mixed component B; S6. Dry-stir component B at 20-30 rpm for 1-2 minutes to loosen the dry material; under continuous low-speed stirring, add component A evenly and continuously within 5-7 minutes. After adding component A, increase the speed to 30-40 rpm and stir for 20 minutes; finally, adjust the speed to 15-20 rpm and stir for 5 minutes to obtain the thin-sprayed flexible support material for mining.

3. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S1, the preparation of β-1,3-glucan-coated iron tailings fine powder is specifically as follows: the iron tailings are dried and ground into fine powder to obtain iron tailings fine powder; the β-1,3-glucan powder is dissolved in deionized water to obtain a β-1,3-glucan solution; and the β-1,3-glucan solution is coated on the iron tailings fine powder using a fluidized bed to obtain β-1,3-glucan-coated iron tailings fine powder.

4. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S1, the weight ratio of the β-1,3-glucan solution to the iron tailings fine powder is 1:

8.

5. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S2 , the acrylic acid ester monomers include butyl acrylate, methyl methacrylate, and acrylic acid in a weight ratio of 60:40:

5.

6. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S2, the weight of the ammonium persulfate is 0.67% of the total weight of the acrylic acid ester monomers.

7. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S3, the weight ratio of RADA16 peptide powder to N,N-dimethylformamide is 1:

13.

8. The method for preparing a thin-sprayed flexible support material for mining according to claim 2, characterized in that: In step S3, the weight ratio of the RADA16 peptide solution, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide reagent, N-hydroxysuccinimide reagent, and acrylate emulsion is 1:1.5:0.75:16.

3.

9. The method for preparing a thin-sprayed flexible support material for mining according to claim 3, characterized in that: The concentration of the β-1,3-glucan solution was 0.1 g / mL.

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