Recyclable mine grouting reinforcement filling agent and preparation method thereof

Abstract

The application discloses a recyclable mine grouting reinforcing filling agent, which comprises a first component and a second component; the first component comprises polyurea polyol, polyvinyl alcohol, polycarbonate dihydric alcohol, a catalyst and a surfactant; and the second component comprises surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate and a plasticizer, wherein the surface-modified chitosan-coated ferrite magnetic microspheres are obtained by surface modification treatment of chitosan-coated ferrite magnetic microspheres with isophorone diisocyanate. The mine grouting reinforcing filling agent of the application does not affect the quality of clean coal, gangue and the surrounding environment after being injected into a coal rock body, and the formed stone body has magnetism, so that the stone body can be effectively recycled.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mine grouting reinforcement filling materials, specifically relating to a recyclable mine grouting reinforcement filling agent and its preparation method. Background Technology

[0002] As mining depths increase, coal mine geological conditions become increasingly complex, with the coal and rock masses at the working faces becoming soft and fractured, reducing mining efficiency and posing safety risks. Advanced chemical grouting reinforcement, characterized by its simple construction and significant reinforcement effect, has become an essential means of controlling roof falls and spalling at working faces. Currently, the grouting reinforcement materials used in coal mining faces are mainly resin-based chemical grouts, including polyurethane and modified polyurethane.

[0003] While chemical grouting can effectively address safety issues such as roof falls and side collapses, its massive grouting volume has adverse effects. Traditional chemical grouting materials, due to the low density of the grout aggregate, leave a large amount of chemical grout aggregate remaining in the clean coal under conventional washing and beneficiation equipment, affecting the quality of the clean coal. Cement-based grouting materials, although having a high aggregate density that can be separated by washing and beneficiation, suffer from high viscosity, poor injectability, long curing time, and insufficient mechanical strength, making them unsuitable for reinforcing mining faces requiring long-term aging. Therefore, it is necessary to conduct in-depth research and improvement on grouting reinforcement filling materials for coal mines. Summary of the Invention

[0004] This invention is based on the inventor's discovery and understanding of the following facts and problems: In related technologies, CN116535597B developed a mine grouting reinforcement material that can be efficiently washed and beneficiated. Although this material has a good washing and beneficiation effect, it greatly increases the specific gravity of the grout aggregate, causing the aggregate to enter the gangue, which has an adverse effect on the subsequent comprehensive utilization of the gangue. Moreover, in current grouting technologies, the huge amount of grout aggregate cannot be recycled, which puts a serious burden on the environment. Therefore, there is an urgent market need to develop a grouting reinforcement material with good grouting reinforcement effect and the ability to recycle the grout aggregate.

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a recyclable grouting and reinforcing filling agent for mining. After injection into the coal and rock mass, the resulting grout-like stone body neither affects the quality of the clean coal nor the gangue and the surrounding environment. Furthermore, the formed stone body is magnetic, enabling its effective recycling.

[0006] The recyclable mine grouting reinforcement and filling agent of this invention comprises: a first component and a second component:

[0007] The first component includes polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst, and surfactant;

[0008] The second component includes surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate (polymeric MDI), and a plasticizer, wherein the surface-modified chitosan-coated ferrite magnetic microspheres are obtained by surface modification treatment of chitosan-coated ferrite magnetic microspheres with isophorone diisocyanate.

[0009] The advantages and technical effects of the recyclable mine grouting reinforcement filling agent of this invention are as follows: 1. In this invention, ferrite magnetic microspheres are introduced into the second component of the filling agent. These magnetic microspheres have magnetic ferrite particles as the core, are coated with chitosan, and are surface modified with isophorone diisocyanate. This results in a large number of active NOC functional groups on the surface of the magnetic microspheres. Under the action of a catalyst, these groups can react and solidify rapidly with the OH groups in the first component. After solidification, the ferrite magnetic microspheres are uniformly dispersed in the matrix, avoiding agglomeration. 2. In this invention, by introducing modified coated ferrite magnetic microspheres into the filling agent, the slurry is injected into the coal and rock mass fissures and solidified, making the slab magnetic. During subsequent washing and separation, it can be quickly recovered and crushed by a magnetic separator. The recovery rate of the solidified slurry can reach over 95%; 3. In this embodiment of the invention, the first component uses a combination of various polyhydroxy alcohols, which, compared with a single polyether polyol, can form a denser interpenetrating network after reacting with the isocyanate in the second component. The inter-chain forces of the polymer chains are significantly enhanced, thus strengthening the strength of the solidified material; 4. In this embodiment of the invention, due to the uniform dispersion of the modified ferrite magnetic microspheres, the stress concentration of the solidified slurry is significantly reduced, greatly improving the mechanical strength of the material, enabling the compressive strength of the material to reach 65 MPa; 5. In this embodiment of the invention, after the mine grouting reinforcement and filling agent is injected into the coal and rock mass, the slurry slurry slurry can be effectively recovered. The slurry slurry slurry does not affect the quality of the clean coal, nor does it affect the gangue and the surrounding environment, which meets the needs of green mine development.

[0010] In some embodiments, the mass ratio of polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst and surfactant in the first component is (20-25):(8-15):(5-10):(1-2):(1-2).

[0011] In some embodiments, in the second component, the mass ratio of the surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer is (40-50):(30-40):(5-10).

[0012] In some embodiments, the catalyst in the first component includes at least one of DB30, DB50 or DB70, all of which can be purchased from Shanghai Sendi Chemical Co., Ltd.; the surfactant includes at least one of TF1348 or DC2550, both of which can be purchased from Dow Chemical Company.

[0013] In some embodiments, the plasticizer in the second component includes at least one of triethyl phosphate, dioctyl phthalate (DOP) or dibutyl phthalate (DBP); the surface-modified chitosan-coated ferrite magnetic microspheres have a particle size of 80-100 nm and a coating thickness of 20-30 nm.

[0014] In some embodiments, the volume ratio of the first component to the second component is (0.8-1.2):1.

[0015] This invention also provides a method for preparing a recyclable mine grouting reinforcement filling agent, comprising the following steps:

[0016] a. Mix polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst and surfactant to obtain the first component;

[0017] b. The second component is prepared by mixing surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer.

[0018] The advantages and technical effects of the recyclable mine grouting reinforcement filling agent preparation method of this invention are as follows: In the method of this invention, ferrite magnetic microspheres are added in the preparation of the second component. The magnetic microspheres have magnetic ferrite particles as the core, are coated with chitosan and surface modified with isophorone diisocyanate, so that the surface of the magnetic microspheres contains a large number of active NOC functional groups. Under the action of a catalyst, they can react and solidify rapidly with the OH groups in the first component. After reaction and solidification, the ferrite magnetic microspheres are uniformly dispersed in the matrix, effectively avoiding the agglomeration of ferrite microspheres, significantly reducing the stress concentration of the slurry solidified material, greatly improving the mechanical strength of the material, and at the same time making the stone body magnetic. During subsequent washing and separation, it can be quickly recovered by magnetic separation device, so that the slurry stone body does not affect the quality of clean coal, nor does it affect gangue and the surrounding environment, which meets the needs of green mine development.

[0019] In some embodiments, step a, the method for preparing the polyurea polyol includes: mixing isocyanate and polyether polyol to obtain a first mixture; mixing polyether polyol and hydrazine hydrate to obtain a second mixture; adding the first mixture to the second mixture for reaction, followed by reflux and vacuum treatment to obtain the polyurea polyol. Preferably, in the first mixture, the mass ratio of isocyanate to polyether polyol is 1:(3-4); in the second mixture, the mass ratio of polyether polyol to hydrazine hydrate is (20-25):1; the mass ratio of isocyanate to hydrazine hydrate is (2-3):1; the reaction time is 30-60 min; after reflux, vacuum treatment is performed at 100-120°C for 1-3 h, with a vacuum degree of 0.05-0.15 MPa, i.e., a gauge pressure of -0.15 MPa to -0.05 MPa.

[0020] In some embodiments, the method for preparing the surface-modified chitosan-coated ferrite magnetic microspheres in step b includes:

[0021] S1. Disperse the nano-ferrite particles in an acetic acid solution of chitosan, then add liquid paraffin, ethyl acetate, and Span 80, and adjust the pH to 8.5-9.5 for the first reaction. Then add formaldehyde and adjust the pH to 4.5-5.5 for the second reaction. Finally, add glutaraldehyde and adjust the pH to 8.5-9.5, and heat for the third reaction. After the reaction, wash, filter, and dry to obtain chitosan-coated nano-ferrite particles.

[0022] S2. The chitosan-coated ferrite nanoparticles obtained in step S1 are dispersed in a solvent, then isophorone diisocyanate and a catalyst are added. After the reaction, the mixture is washed and dried to obtain surface-modified chitosan-coated ferrite magnetic microspheres. The catalyst includes at least one of dibutyltin dilaurate or stannous octoate.

[0023] In some embodiments, in step S1, the nanoferrite particles are Mn 0.5 Co 0.5 Fe2O4, preferably, the Mn 0.5 Co 0.5 The preparation method of Fe2O4 nano-ferrite particles includes: adding sodium hydroxide to an aqueous solution of MnCl2, Co(NO3)3 and FeCl3 to adjust the pH to 11-12, then adding sodium acetate, and reacting in a polytetrafluoroethylene reactor at 150-200℃ for 8-15 h. After the reaction, the particles are washed, magnetically separated and dried to obtain MnCl2 nano-ferrite particles. 0.5 Co 0.5 Fe2O4 nano-ferrite particles.

[0024] In some embodiments, in step S1, the chitosan acetic acid solution contains 1-2% chitosan by mass; the volume ratio of liquid paraffin, ethyl acetate, and Span 80 is (120-180):(15-25):1; the volume-to-mass ratio of formaldehyde to nano-ferrite particles is (3-5) ml:1 g; the volume-to-mass ratio of glutaraldehyde to nano-ferrite particles is (1-1.5) ml:1 g; the first reaction temperature is 40-60℃ and the reaction time is 10-20 min; the second reaction temperature is 40-60℃ and the reaction time is 20-40 min; and the third reaction temperature is 60-80℃ and the reaction time is 2-4 h.

[0025] In some embodiments, in step S2, the solvent includes at least one of dimethyl sulfoxide or DMF; the mass ratio of the chitosan-coated ferrite nanoparticles to isophorone diisocyanate is 1:25-40; the mass of the catalyst is 0.5-1% of the mass of isophorone diisocyanate; the reaction temperature is 20-30°C, and the reaction time is 8-15 h. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of surface-modified chitosan-coated ferrite magnetic microspheres according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the structure of the solidified material after the consolidation of the recyclable mining grouting reinforcement filling agent according to an embodiment of the present invention. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] The recyclable mine grouting reinforcement and filling agent of this invention comprises: a first component and a second component:

[0030] The first component includes polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst, and surfactant;

[0031] The second component includes surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate (polymeric MDI), and a plasticizer, wherein the surface-modified chitosan-coated ferrite magnetic microspheres are obtained by surface modification treatment of chitosan-coated ferrite magnetic microspheres with isophorone diisocyanate.

[0032] In the recyclable mine grouting reinforcement filling agent of this invention, ferrite magnetic microspheres are introduced into the second component. These magnetic microspheres have magnetic ferrite particles as the core, are coated with chitosan, and undergo surface modification treatment with isophorone diisocyanate. This results in a large number of active NOC functional groups on the surface of the magnetic microspheres. Under the action of a catalyst, these groups can rapidly react and solidify with the OH groups in the first component. After solidification, the ferrite magnetic microspheres are uniformly dispersed in the matrix, preventing agglomeration. In this embodiment, by introducing modified coated ferrite magnetic microspheres into the filling agent, the solidified rock becomes magnetic after the grout is injected into the coal and rock mass fissures and solidifies. During subsequent washing and separation, it can be rapidly recovered using a magnetic separator, and the solidified grout after crushing can be recycled. The efficiency can reach over 95%; in this embodiment of the invention, the first component uses a combination of various polyhydroxy alcohols, which, compared with a single polyether polyol, can form a denser interpenetrating network after reacting with isocyanate in the second component, significantly enhancing the inter-chain forces of the polymer chains and strengthening the strength of the solidified material; in this embodiment of the invention, due to the uniform dispersion of the modified ferrite magnetic microspheres, the stress concentration of the slurry solidified material is significantly reduced, greatly improving the mechanical strength of the material, enabling the compressive strength of the material to reach 65 MPa; in this embodiment of the invention, after the mine grouting reinforcement filling agent is injected into the coal and rock mass, the slurry slurry slurry can be effectively recovered, and the slurry slurry slurry does not affect the quality of clean coal, nor does it affect gangue and the surrounding environment, which meets the needs of green mine development.

[0033] In some embodiments, the mass ratio of polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst, and surfactant in the first component is (20-25):(8-15):(5-10):(1-2):(1-2). In this embodiment of the invention, the use of a combination of polyurea polyol, polyvinyl alcohol, and polycarbonate diol in the first component to provide OH groups for the reaction is beneficial to improving the strength of the solidified material.

[0034] In some embodiments, in the second component, the mass ratio of the surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer is (40-50):(30-40):(5-10).

[0035] In some embodiments, the catalyst in the first component includes at least one of DB30, DB50, or DB70; and the surfactant includes at least one of TF1348 or DC2550.

[0036] In some embodiments, the plasticizer in the second component includes at least one of triethyl phosphate, dioctyl phthalate (DOP) or dibutyl phthalate (DBP); the surface-modified chitosan-coated ferrite magnetic microspheres have a particle size of 80-100 nm and a coating thickness of 20-30 nm.

[0037] In some embodiments, the volume ratio of the first component to the second component is (0.8-1.2):1. In these embodiments, using a preferred ratio of the first and second components is beneficial for further improving the application effect of the filler, enabling the material to not only possess excellent compressive strength but also increase the recovery rate of the stones.

[0038] This invention also provides a method for preparing a recyclable mine grouting reinforcement filling agent, comprising the following steps:

[0039] a. Mix polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst and surfactant to obtain the first component;

[0040] b. The second component is prepared by mixing surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer.

[0041] In the preparation method of the recyclable mine grouting reinforcement filling agent of this invention embodiment, ferrite magnetic microspheres are added in the preparation of the second component. The magnetic microspheres have magnetic ferrite particles as the core, are coated with chitosan and surface modified with isophorone diisocyanate, so that the surface of the magnetic microspheres contains a large number of active NOC functional groups. Under the action of a catalyst, they can react and solidify rapidly with the OH groups in the first component. After reaction and solidification, the ferrite magnetic microspheres are uniformly dispersed in the matrix, effectively avoiding the agglomeration of ferrite microspheres, significantly reducing the stress concentration of the slurry solidified material, greatly improving the mechanical strength of the material, and at the same time making the stone body magnetic. During subsequent washing and separation, it can be quickly recovered by magnetic separation device, so that the slurry stone body does not affect the quality of clean coal, nor does it affect gangue and the surrounding environment, which meets the needs of green mine development.

[0042] In some embodiments, step a, the method for preparing the polyurea polyol includes: mixing isocyanate and polyether polyol to obtain a first mixture; mixing polyether polyol and hydrazine hydrate to obtain a second mixture; adding the first mixture to the second mixture at room temperature to react, releasing a large amount of heat during the reaction; refluxing after the reaction; and heating under vacuum to remove residual monomers to obtain the polyurea polyol. Preferably, in the first mixture, the mass ratio of isocyanate to polyether polyol is 1:(3-4); in the second mixture, the mass ratio of polyether polyol to hydrazine hydrate is (20-25):1; the mass ratio of isocyanate to hydrazine hydrate is (2-3):1; the reaction time is 30-60 min; after reflux, vacuum treatment is performed at 100-120°C for 1-3 h, with a vacuum degree of 0.05-0.15 MPa, i.e., a gauge pressure of -0.15 MPa to -0.05 MPa. In this embodiment of the invention, the introduction of the polyurea polyol prepared by the method of the present invention into the first component is beneficial to further enhance the strength of the material after the first component and the second component react and solidify.

[0043] In some embodiments, the method for preparing the surface-modified chitosan-coated ferrite magnetic microspheres in step b includes:

[0044] S1. Disperse the nano-ferrite particles in an acetic acid solution of chitosan, preferably with a chitosan mass percentage of 1-2%. Then add liquid paraffin, ethyl acetate, and Span 80, preferably in a volume ratio of (120-180):(15-25):1. Adjust the pH to 8.5-9.5 for the first reaction. The preferred temperature for the first reaction is 40-60℃, and the reaction time is 10-20 min. Afterward, add formaldehyde, with a volume mass ratio of formaldehyde to nano-ferrite particles of... The preferred ratio is (3-5) ml: 1 g. The pH is adjusted to 4.5-5.5 for the second reaction. The preferred temperature for the second reaction is 40-60℃, and the reaction time is 20-40 min. Finally, glutaraldehyde is added. The preferred volume-to-mass ratio of glutaraldehyde to nano-ferrite particles is (1-1.5) ml: 1 g. The pH is adjusted to 8.5-9.5. The third reaction is carried out by heating. The preferred temperature for the third reaction is 60-80℃, and the reaction time is 2-4 h. After the reaction, the nano-ferrite particles are obtained by washing, filtering, and drying.

[0045] S2. The chitosan-coated ferrite nanoparticles obtained in step S1 are dispersed in a solvent, followed by the addition of isophorone diisocyanate and a catalyst. After reaction, the mixture is washed and dried to obtain surface-modified chitosan-coated ferrite magnetic microspheres. The catalyst comprises at least one of dibutyltin dilaurate or stannous octoate. Preferably, the solvent comprises at least one of dimethyl sulfoxide or DMF; the mass ratio of the chitosan-coated ferrite nanoparticles to isophorone diisocyanate is 1:25-40; the mass of the catalyst is 0.5-1% of the mass of isophorone diisocyanate; the reaction temperature is 20-30℃, and the reaction time is 8-15 h.

[0046] In this embodiment of the invention, chitosan is used to coat the nano-ferrite particles, and the surface is modified with isophorone diisocyanate. The amount of isophorone diisocyanate is optimized to increase the number of active NOC functional groups on the surface of the magnetic microspheres, allowing them to react and solidify rapidly with the OH groups in the filler under the action of a catalyst. This further improves the dispersibility of the magnetic microspheres in the matrix, increases the compressive strength of the material, and improves the recovery rate after the stone body is crushed.

[0047] In some embodiments, in step S1, the nanoferrite particles are Mn 0.5 Co 0.5 Fe2O4, preferably, the Mn 0.5 Co 0.5 The preparation method of Fe2O4 nano-ferrite particles includes: adding sodium hydroxide to an aqueous solution of MnCl2, Co(NO3)3 and FeCl3 to adjust the pH, then adding sodium acetate, reacting in a polytetrafluoroethylene reactor, and after the reaction, washing, magnetic separation and drying to obtain MnCl2 nano-ferrite particles. 0.5 Co 0.5 More preferably, the pH of the Fe2O4 nano-ferrite particles adjusted by sodium hydroxide is 11-12, the reaction temperature is 150-200℃, and the reaction time is 8-15h.

[0048] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0049] Example 1

[0050] I. Preparation of Surface-Modified Chitosan-Coated Ferrite Magnetic Microspheres

[0051] 1. Preparation of nano-ferrite particles: 0.27g MnCl2·4H2O, 0.4g Co(NO3)3·6H2O, and 1.49g FeCl3·6H2O were added to beakers respectively, followed by 35ml of deionized water to dissolve them completely. A 1.5mol / L sodium hydroxide solution was slowly added dropwise to adjust the pH to between 11 and 12. Then, 10ml of anhydrous sodium acetate was added. The solution was stirred for 30min and then poured into a 100ml polytetrafluoroethylene reactor. The reaction was carried out at 170℃ for 10h. The reactor was cooled to room temperature, and the sample was washed three times with deionized water and three times with anhydrous ethanol. During the washing process, a neodymium iron boron magnet was used for magnetic separation to remove impurities. The resulting black solid product was dried in a vacuum drying oven at 70℃ for 9h, and then ground to obtain MnCl2·4H2O. 0.5 Co 0.5 Fe2O4 nano-ferrite particles.

[0052] 2. Chitosan coating: Prepare a 3wt% acetic acid aqueous solution, then add chitosan and stir at room temperature for 40 min to obtain 100 ml of a solution containing 1.5wt% chitosan. Add 5g Mn... 0.5 Co 0.5 Fe2O4 nano-ferrite particles were added to a chitosan solution and stirred for 1.5 hours under nitrogen protection, with the stirring temperature controlled at 50℃. Mn 0.5 Co 0.5 After uniformly dispersing Fe2O4 nano-ferrite particles, 150 ml of liquid paraffin, 20 ml of ethyl acetate, and 1 ml of Span 80 (volume ratio 150:20:1) were added. The pH was maintained at 50°C for 15 min, and the reaction was allowed to proceed. Then, 20 ml of formaldehyde (volume ratio of formaldehyde to nano-ferrite particles 4 ml:1 g) was added, and the pH was adjusted to 5.0. The reaction was continued at 50°C for 30 min. Subsequently, 6 ml of glutaraldehyde (volume ratio of glutaraldehyde to nano-ferrite particles 1.2 ml:1 g) was added, and the pH was adjusted to 9.0. The temperature was raised to 70°C, and the reaction was allowed to proceed for 3 h. After centrifugation, the mixture was washed with deionized water and filtered with ethanol, repeating this process 3-5 times. Finally, the mixture was vacuum dried at 80°C for 2 h to obtain chitosan-coated Mn. 0.5 Co 0.5 Fe2O4 ferrite particles.

[0053] 3. Preparation of surface-modified chitosan-coated ferrite magnetic microspheres: 1.2g of chitosan-coated Mn 0.5 Co 0.5 Fe2O4 ferrite particles were dispersed in 40g DMSO and ultrasonically dispersed for 2 hours. After uniform dispersion, the dispersion was transferred to a flask. Then, 36g of isophorone diisocyanate (i.e., chitosan-coated MnO4) was added. 0.5 Co 0.5Fe₂O₄ ferrite and isophorone diisocyanate (mass ratio 1:30), along with 6 drops of dibutyltin dilaurate (DBTDL, 0.8% of the mass of isophorone diisocyanate), were reacted under nitrogen protection for 12 h. The resulting product was initially separated using a magnet. The product was washed three times with ethyl acetate and vacuum dried at 45 °C for 2 h to obtain surface-modified chitosan-coated ferrite magnetic microspheres. The microspheres had a particle size of 80-100 nm, and the chitosan coating thickness was 20-30 nm. A schematic diagram of the structure of the prepared magnetic microspheres is shown below. Figure 1 As shown.

[0054] II. Preparation of Polyurea Polyol: 15.3g of isocyanate TDI and 50.6g of polyether polyol 330N (mass ratio 1:3.3) were uniformly mixed to obtain a homogeneous mixture for later use. 130g of polyether polyol 330N and 5.7g of hydrazine hydrate (mass ratio 22.8:1) were added to a flask and stirred at room temperature for 20min. The homogeneous mixture of isocyanate and polyether polyol was then quickly poured into the flask to obtain the reaction mixture, wherein the mass ratio of isocyanate to hydrazine hydrate was 2.7:1. Stirring was continued for 40min. After the reaction, the mixture was refluxed and vacuum-treated at 120℃ for 2h, with the vacuum degree controlled at 0.1MPa (i.e., gauge pressure -0.1MPa), to obtain polyurea polyol.

[0055] III. Preparation of recyclable mine grouting reinforcement and filling agents

[0056] Preparation of the first component: 22 parts by weight of polyurea polyol, 12 parts by weight of polyvinyl alcohol, 8 parts by weight of polycarbonate diol, 1 part by weight of catalyst DB30, and 1 part by weight of surfactant TF1348 (i.e., the mass ratio of each substance is 22:12:8:1:1) are mixed evenly to obtain the first component.

[0057] Preparation of the second component: 45 parts by weight of the surface-modified chitosan-coated ferrite magnetic microspheres prepared above, 35 parts by weight of polymeric MDI (polymethylene polyphenyl polyisocyanate) and 6 parts by weight of triethyl phosphate (i.e., the mass ratio of each substance is 45:35:6) are uniformly mixed to obtain the second component.

[0058] IV. Injecting mining grouting reinforcement and filling agent into the coal and rock mass.

[0059] Start the grouting pump and mix the first and second components at a volume ratio of 1:1. The grout is then quickly injected into the coal and rock mass fissures after passing through the three-way mixer.

[0060] Example 2

[0061] The method is the same as in Example 1, except that the amount of isophorone diisocyanate added is different in the preparation of surface-modified chitosan-coated ferrite magnetic microspheres, which is adjusted to be chitosan-coated Mn 0.5 Co 0.5 The mass ratio of Fe2O4 ferrite to isophorone diisocyanate is 1:40.

[0062] Example 3

[0063] The method is the same as in Example 1, except that the amount of isophorone diisocyanate added is different in the preparation of surface-modified chitosan-coated ferrite magnetic microspheres, which is adjusted to be chitosan-coated Mn 0.5 Co 0.5 The mass ratio of Fe2O4 ferrite to isophorone diisocyanate is 1:25.

[0064] Example 4

[0065] The method is the same as in Example 1, except that in the step of injecting the grouting reinforcement filling agent into the coal and rock mass, the volume ratio of the first component and the second component in the injected filling agent is 1.1:1.

[0066] Example 5

[0067] The method is the same as in Example 1, except that in the step of injecting the mining grouting reinforcement filling agent into the coal and rock mass, the volume ratio of the first component and the second component in the injected filling agent is 0.9:1.

[0068] Example 6

[0069] The method is the same as in Example 1, except that the total amount of polyurea polyol and polyvinyl alcohol added in the first component remains unchanged, and the weight ratio of the two is 20:14.

[0070] Example 7

[0071] The method is the same as in Example 1, except that the total amount of polyurea polyol and polyvinyl alcohol added in the first component remains unchanged, and the weight ratio of the two is 25:9.

[0072] Comparative Example 1

[0073] The method is the same as in Example 1, except that in the preparation of surface-modified chitosan-coated ferrite magnetic microspheres in step one, steps 2 and 3 are omitted; and in the preparation of the second component of the recyclable mine grouting reinforcement filling agent in step three, the surface-modified chitosan-coated ferrite magnetic microspheres are replaced with uncoated and unmodified Mn. 0.5 Co 0.5 Fe2O4 nano-ferrite particles.

[0074] Comparative Example 2

[0075] The method is the same as in Example 1, except that in the preparation of surface-modified chitosan-coated ferrite magnetic microspheres in step one, step 3 is omitted; and in the preparation of the second component of the recyclable mine grouting reinforcement filling agent in step three, the surface-modified chitosan-coated ferrite magnetic microspheres are replaced with unmodified chitosan-coated Mn. 0.5 Co 0.5 Fe2O4 ferrite particles.

[0076] Comparative Example 3

[0077] Similar to the method in Example 1, the second component does not contain surface-modified chitosan-coated ferrite magnetic microspheres, but instead replaces the magnetic microspheres with an equal amount of polymeric MDI.

[0078] Comparative Example 4

[0079] The method is the same as in Example 1, except that 22 parts by weight of polyurea polyol, 12 parts by weight of polyvinyl alcohol, and 8 parts by weight of polycarbonate diol in the first component of step three are replaced with 42 parts by weight of polyether polyol MN400.

[0080] Comparative Example 5

[0081] The method is the same as in Example 1, except that 6 parts by weight of triethyl phosphate in the second component of step three is replaced with 6 parts by weight of polymeric MDI.

[0082] Comparative Example 6

[0083] The method is the same as in Example 1, except that the polycarbonate diol in the first component in step three is replaced with an equal amount of polyurea polyol.

[0084] Comparative Example 7

[0085] The method is the same as in Example 1, except that the polycarbonate diol in the first component in step three is replaced with an equal amount of polyvinyl alcohol.

[0086] Comparative Example 8

[0087] The grouting reinforcement material for mining prepared in Example 1 of Publication No. CN116535597B was used as the reinforcement filler.

[0088] The performance of the stone bodies formed after adding mining grouting reinforcement and filling agent in each embodiment and comparative example of this application was tested, and the test results are shown in Table 1.

[0089] 1. Compressive strength: Tested in accordance with AQ / T 1089-2020.

[0090] 2. Maximum reaction temperature: refers to the highest temperature of the core point of the slurry solidified material after the first and second components are mixed and reacted, and is tested in accordance with AQ / T 1089-2020.

[0091] 3. Solids recovery rate, solids content in clean coal, and solids content in gangue: The actual washing process was simulated in the laboratory. 10 kg of coarse coal (8.5 kg of clean coal, 1.5 kg of gangue, approximately 70 mm in size) was artificially prepared. After mixing the clean coal and gangue, the mixture was placed in a test chamber. 2 kg of reinforcing and filling agent was injected using a pneumatic grouting pump. The weight was recorded as M. 充填剂 After the slurry has completely solidified, the solidified material is broken up and then placed in a washing and screening heavy medium. A magnet is used to absorb the solidified slurry material. The recovered reinforcing filler, clean coal, and gangue are dried and weighed, and the weight is recorded as M. 固 M 精 and M 矸 The calculation is performed using the weighing method. Details are as follows:

[0092] Solid recovery rate = M 固 / M 充填剂 ;

[0093] The content of solids in the clean coal after separation = (M 精 -8.5) / M 精 ;

[0094] The content of solids in the separated coal gangue = (M 矸 -1.5) / M 矸 .

[0095] Table 1

[0096]

[0097] As shown in Table 1, the compressive strength of the solidified material formed by the reinforcing filling agent in Examples 1-7 of this invention can reach approximately 60 MPa or higher, the maximum reaction temperature is below 100℃, the recovery rate of the solidified material after crushing and washing can reach over 94%, the solidified material content in the separated clean coal can be controlled below 0.9%, and the solidified material content in the separated gangue can be controlled below 2.8%. This invention, by using a combination of various polyhydroxy alcohols in the first component and introducing isophorone diisocyanate-modified and chitosan-coated magnetic microspheres in the second component, ensures that the solidified material formed after the reinforcing filling agent is injected into the coal and rock mass fissures not only has high compressive strength but also allows for effective recovery of the solidified material after crushing. The low solidified material content entering the clean coal and gangue effectively guarantees the quality of the clean coal and does not affect the gangue or the surrounding environment.

[0098] In Comparative Examples 1 and 2, compared with Example 1, the magnetic microspheres used were not coated and / or modified. The magnetic microspheres were prone to agglomeration in the mine grouting reinforcement filling agent, which was not conducive to the diffusion of the reinforcement filling agent in the coal and rock mass fissures. This easily caused stress concentration, resulting in a significant decrease in the mechanical strength of the solidified material. Furthermore, due to the uneven dispersion of the magnetic microspheres, the magnetic distribution after crushing and washing was uneven, and the recovery rate decreased significantly.

[0099] In Comparative Example 3, compared with Example 1, no magnetic microspheres were introduced. Although the mechanical strength was higher, the maximum reaction temperature increased significantly to 127°C. Furthermore, the solids could not be effectively recovered, which seriously affected the quality of the clean coal. At the same time, a large amount of solids entered the gangue.

[0100] In Comparative Example 4, compared with Example 1, only one type of alcohol, polyether polyol, was used in the first component. Although the recovery rate of the solidified material could reach more than 90%, the strength of the solidified material decreased significantly.

[0101] In Comparative Example 5, compared with Example 1, no plasticizer was introduced, resulting in a decrease in the strength of the solidified material and a significant reduction in the recovery rate of the solidified material.

[0102] In Comparative Examples 6 and 7, compared with Example 1, no polycarbonate diol was introduced into the first component. Although the recovery rate of the solids was comparable to that of Example 1, the mechanical strength of the solids formed was significantly lower than that of Example 1.

[0103] In Comparative Example 8, the grouting reinforcement material for mining prepared in Example 1 of CN116535597B was used. Although the maximum reaction temperature was low and the quality of the clean coal was high, the mechanical strength of the solidified material was low and the recovery rate was very low, with a large amount of solidified material entering the gangue.

[0104] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0105] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A recyclable grouting and reinforcing agent for mining, characterized in that, include: First component and second component: The first component includes polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst, and surfactant; The second component comprises surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and a plasticizer, wherein the surface-modified chitosan-coated ferrite magnetic microspheres are made by coating chitosan with Mn using isophorone diisocyanate. 0.5 Co 0.5 Fe2O4 ferrite magnetic microspheres were surface modified.

2. The recyclable mine grouting reinforcement and filling agent according to claim 1, characterized in that, In the first component, the mass ratio of polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst and surfactant is (20-25):(8-15):(5-10):(1-2):(1-2).

3. The recyclable mine grouting reinforcement and filling agent according to claim 1, characterized in that, In the second component, the mass ratio of the surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer is (40-50):(30-40):(5-10).

4. The recyclable mine grouting reinforcement and filling agent according to claim 1, characterized in that, In the first component, the catalyst includes at least one of DB30, DB50, or DB70; the surfactant includes at least one of TF1348 or DC2550. In the second component, the plasticizer includes at least one of triethyl phosphate, dioctyl phthalate, or dibutyl phthalate; the surface-modified chitosan-coated ferrite magnetic microspheres have a particle size of 80-100 nm and a coating thickness of 20-30 nm.

5. The recyclable mine grouting reinforcement and filling agent according to claim 1, characterized in that, The volume ratio of the first component to the second component is (0.8-1.2):

1.

6. A method for preparing a recyclable mine grouting reinforcement and filling agent, characterized in that, Includes the following steps: a. Mix polyurea polyol, polyvinyl alcohol, polycarbonate diol, catalyst and surfactant to obtain the first component; b. The second component is prepared by mixing surface-modified chitosan-coated ferrite magnetic microspheres, polymethylene polyphenyl polyisocyanate, and plasticizer.

7. The method for preparing the recyclable mine grouting reinforcement and filling agent according to claim 6, characterized in that, In step a, the method for preparing the polyurea polyol includes: mixing isocyanate with polyether polyol to obtain a first mixture; and mixing polyether polyol with hydrazine hydrate to obtain a second mixture. The first mixture was added to the second mixture for reaction, followed by reflux condensation and vacuum treatment to obtain polyurea polyol; wherein... In the first mixture, the mass ratio of isocyanate to polyether polyol is 1:(3-4); In the second mixture, the mass ratio of the polyether polyol to hydrazine hydrate is (20-25):1; The mass ratio of the isocyanate to hydrazine hydrate is (2-3):1; The reaction time is 30-60 minutes; After condensation and reflux, the mixture is vacuum-treated at 100-120℃ for 1-3 hours with a vacuum degree of 0.05-0.15MPa.

8. The method for preparing the recyclable mine grouting reinforcement and filling agent according to claim 6, characterized in that, In step b, the method for preparing the surface-modified chitosan-coated ferrite magnetic microspheres includes: S1. Mn 0.5 Co 0.5 Fe2O4 nano-ferrite particles were dispersed in an acetic acid solution of chitosan, then liquid paraffin, ethyl acetate, and Span 80 were added, and the pH was adjusted to 8.5-9.5 for the first reaction. Formaldehyde was then added, and the pH was adjusted to 4.5-5.5 for the second reaction. Finally, glutaraldehyde was added, and the pH was adjusted to 8.5-9.

5. The mixture was then heated for the third reaction. After the reaction, the mixture was washed, filtered, and dried to obtain chitosan-coated nano-ferrite particles. S2. The chitosan-coated ferrite nanoparticles obtained in step S1 are dispersed in a solvent, then isophorone diisocyanate and a catalyst are added. After the reaction, the mixture is washed and dried to obtain surface-modified chitosan-coated ferrite magnetic microspheres. The catalyst includes at least one of dibutyltin dilaurate or stannous octoate.

9. The method for preparing the recyclable mine grouting reinforcement and filling agent according to claim 8, characterized in that, In step S1, Mn 0.5 Co 0.5 The preparation method of Fe2O4 nano-ferrite particles includes: adding sodium hydroxide to an aqueous solution of MnCl2, Co(NO3)3 and FeCl3 to adjust the pH to 11-12, then adding sodium acetate, and reacting in a polytetrafluoroethylene reactor at 150-200℃ for 8-15 h. After the reaction, the particles are washed, magnetically separated and dried to obtain MnCl2 nano-ferrite particles. 0.5 Co 0.5 Fe2O4 nano-ferrite particles.

10. The method for preparing the recyclable mine grouting reinforcement and filling agent according to claim 8, characterized in that, In step S1, the chitosan acetic acid solution contains 1-2% chitosan by mass; the volume ratio of liquid paraffin, ethyl acetate, and Span 80 is (120-180):(15-25):1; the volume-to-mass ratio of formaldehyde to nano-ferrite particles is (3-5) ml:1 g; the volume-to-mass ratio of glutaraldehyde to nano-ferrite particles is (1-1.5) ml:1 g; the temperature of the first reaction is 40-60℃ and the reaction time is 10-20 min; the temperature of the second reaction is 40-60℃ and the reaction time is 20-40 min; the temperature of the third reaction is 60-80℃ and the reaction time is 2-4 h. In step S2, the solvent includes at least one of dimethyl sulfoxide or DMF; the mass ratio of the chitosan-coated ferrite nanoparticles to isophorone diisocyanate is 1:25-40; the mass of the catalyst is 0.5-1% of the mass of isophorone diisocyanate; the reaction temperature is 20-30℃, and the reaction time is 8-15h.

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