A liquid polymer inhibitor for coal mines and a method for preparing the same

Abstract

This invention belongs to the field of antioxidant technology and discloses a liquid polymer inhibitor for coal mines and its preparation method. The invention provides a method for preparing a liquid polymer inhibitor for coal mines, comprising: copolymerizing an acrylate compound to obtain a hydrophobic acrylate polymer; placing the hydrophobic acrylate polymer in a solution environment containing a hydrophilic polymer precursor, a crosslinking agent, a surfactant, an antioxidant, and a solvent; and cooling to room temperature after the heating reaction is completed to obtain the liquid polymer inhibitor. This invention uses hydrophobic and hydrophilic polymers through an interpenetrating network to obtain a liquid polymer inhibitor, effectively solving the technical problems of low inhibition rate and easy failure at high temperatures in traditional inorganic oxygen-blocking fire extinguishing agents.

Description

Technical Field

[0001] This invention belongs to the field of antioxidant technology and discloses a liquid polymer inhibitor for use in coal mines and its preparation method. Background Technology

[0002] In chemistry, any substance that can slow down a chemical reaction is called an inhibitor. Inhibitors are chemical agents that prevent coal from oxidizing and spontaneously combusting; they are also called oxygen inhibitors or antioxidants. Inhibitor fire prevention technology utilizes inorganic salt compounds such as calcium chloride, magnesium chloride, ammonium chloride, and water glass, which can inhibit coal oxidation, by spraying them into the goaf or injecting them into the coal body to inhibit or delay coal oxidation, thereby preventing spontaneous combustion. Currently commonly used inhibitors include calcium chloride, magnesium chloride, table salt, and certain industrial waste liquids. For example, CN101487399B provides an inhibitor that can prevent spontaneous combustion of coal and its preparation method, which is composed of the following chemical raw materials, by weight: 88 parts magnesium chloride; 4 parts sodium tetraborate and sodium gluconate mixed in any ratio of 1:9 to 6:4; and 8 parts sodium dodecyl sulfate. However, commonly used inhibitors are corrosive to equipment and pipelines, requiring nozzle replacement every 2-3 months. They dehydrate quickly, have short water retention time, short inhibition life, are volatile, have low inhibition rates, and their inhibition effect decreases significantly with increasing temperature, resulting in mediocre fire prevention and extinguishing effects, and even less ideal fire extinguishing effects. The addition ratio is generally 10-20%, requiring large transportation volumes and heavy workloads for workers. Furthermore, they are highly irritating to the skin, pollute the working environment in tunnels, and corrode metal equipment such as working face supports. Commonly used inhibitors have relatively low inhibition rates, around 50%. Summary of the Invention

[0003] The purpose of this invention is to address the technical problems of low inhibition rate, significant pipeline corrosion, and easy failure at high temperatures associated with ordinary inorganic inhibitors. To solve these problems, this invention provides a liquid polymer inhibitor for coal mines and its preparation method to meet this need in the field.

[0004] On one hand, the present invention relates to a method for preparing a liquid polymer inhibitor for coal mines, comprising: copolymerizing an acrylate compound to obtain a hydrophobic acrylate polymer;

[0005] The hydrophobic acrylate polymer is placed in a solution containing a hydrophilic polymer precursor, a crosslinking agent, a surfactant, an antioxidant, and a solvent. After the reaction is heated, the solution is cooled to room temperature to obtain the liquid polymer inhibitor.

[0006] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the hydrophilic polymer precursor is an epoxy compound;

[0007] The epoxy compound is selected from at least one of glycidyl methacrylate, tetrahydrofurfuryl methacrylate, and 3,4-epoxycyclohexyl methacrylate.

[0008] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the acrylate compound is selected from at least one of methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

[0009] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the crosslinking agent is selected from at least one of borax, epichlorohydrin, and toluene diisocyanate.

[0010] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the surfactant is selected from at least one of polyoxyethylene sorbitan fatty acid ester, sulfobetaine, and lecithin.

[0011] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the antioxidant is a hindered phenolic antioxidant.

[0012] Furthermore, in the preparation method of the liquid polymer inhibitor for coal mines provided by the present invention, the solvent is selected from at least one of methanol, ethanol, and butanol.

[0013] On the other hand, the present invention relates to a liquid polymer inhibitor for coal mines, which is prepared by the aforementioned method for preparing liquid polymer inhibitors for coal mines.

[0014] Furthermore, in the liquid polymer inhibitor for coal mines provided by the present invention, the raw materials, by mass, consist of the following components:

[0015] 100-300 parts of the hydrophobic acrylate polymer described above;

[0016] 120-200 parts of the hydrophilic polymer precursor described above;

[0017] 5-10 parts of the crosslinking agent described above;

[0018] 1 to 10 parts of the surfactant described;

[0019] 30-60 parts of the antioxidant described;

[0020] 20 to 80 parts of the solvent.

[0021] Furthermore, in the liquid polymer inhibitor for coal mines provided by the present invention, the inhibition rate of the liquid polymer inhibitor for coal mines is not less than 95%.

[0022] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects or advantages:

[0023] This invention utilizes hydrophobic and hydrophilic polymers through an interpenetrating network to obtain a liquid polymer inhibitor, effectively solving the technical problems of traditional inorganic oxygen-barrier fire extinguishing agents, such as low inhibition rate, easy failure at high temperatures, corrosiveness to equipment and pipelines, short inhibition life, easy volatility, large addition ratio, large transportation volume, significant skin irritation, pollution of the roadway working environment, and corrosive hazards to metal equipment such as working face supports. The liquid polymer inhibitor for coal mines prepared by this invention has a high inhibition rate. The inhibition rate of conventional calcium chloride and / or magnesium chloride is about 50%, while the inhibition rate of the inhibitor of this invention is not less than 95%. It still maintains a good inhibition effect at 180℃, and the inhibition life is extended by more than 30 days compared with traditional inhibitors (calcium chloride and / or magnesium chloride). At the same time, it greatly reduces the addition ratio, reduces transportation volume and worker workload, reduces skin irritation, reduces pollution of the roadway working environment and corrosion hazards to metal equipment such as working face supports, and significantly improves the safety level of coal mine production. Detailed Implementation

[0024] The technical solution of the present invention will be described below with reference to embodiments. However, the present invention is not limited to the following embodiments. Unless otherwise specified, the experimental and detection methods described in each embodiment are conventional methods; the reagents and materials described are commercially available unless otherwise specified. Unless otherwise specified, all percentages in the following embodiments refer to mass percentages. Unless otherwise specified, all proportions in the following embodiments refer to mass ratios.

[0025] Example 1 This example provides the preparation process of hydrophobic acrylate polymer A.

[0026] 1.6 mol of methyl methacrylate, 2.3 mol of ethyl methacrylate, 1.4 mol of butyl methacrylate, 0.2 mol of α-methylstyrene dimer, 0.5 mol of benzoyl peroxide and 20 mol of N-methylpyrrolidone were taken and heated to 70 °C for 5 h under stirring. After cooling to room temperature, a hydrophobic acrylate polymer with Mw=7362 and PDI=2.0 was obtained.

[0027] Based on the hydrophobic acrylate polymer obtained in Example 1, the following preparation of a liquid polymer inhibitor for use in coal mines is carried out.

[0028] Example 2 This example provides the preparation process of hydrophobic acrylate polymer B.

[0029] Take 1.5 mol methyl methacrylate, 1.5 mol ethyl methacrylate, 2.0 mol butyl methacrylate, 0.4 mol dodecyl mercaptan, 0.5 mol benzoyl peroxide and 15 mol N-methylpyrrolidone, heat to 80℃ for 6 h with stirring, and then cool to room temperature to obtain a hydrophobic acrylate polymer Mw=9942, PDI=1.8.

[0030] Based on the hydrophobic acrylate polymer obtained in Example 2, the following preparation of a liquid polymer inhibitor for use in coal mines is carried out.

[0031] Example 3 This example provides a preparation process for a liquid polymer inhibitor for use in coal mines.

[0032] The raw material composition of each experimental group is shown in the table below:

[0033]

[0034] Under nitrogen protection, the above raw materials were added to a three-necked flask and heated to 70°C for 5 hours with stirring. After cooling to room temperature, a liquid polymer inhibitor for use in coal mines was obtained.

[0035] Example 4 This example provides the performance test results of the liquid polymer inhibitor for coal mines prepared in Example 3.

[0036] The selected coal sample was processed into coal powder and placed in the adsorption cylinder of a coal oxygen adsorption detection device. The remaining space inside the adsorption cylinder was filled with air to simulate the air environment during coal spontaneous combustion. A gas outlet and pressure gauge were installed on the adsorption cylinder, and the gas outlet was connected to a gas chromatograph. Based on the changes in oxygen concentration and pressure inside the adsorption cylinder before and after adsorption, the amount of oxygen adsorbed by coal from the air under normal temperature and pressure conditions was determined. The liquid polymer inhibitor provided in Example 2 was mixed with water, and the concentration of the liquid polymer inhibitor was 20% to obtain the final product. The final product was evenly sprayed onto the surface of the coal sample at a spraying pressure of 2.7 MPa, a single spray thickness of 4 mm, and three cycles of spraying with a 2-hour interval between sprayings. For the first spraying, it was necessary to ensure that the fire-retardant material completely covered the surface of the coal sample. After spraying, the sample was left to stand for 12 hours and recorded as the inhibited coal sample. Take 50g of each of the raw coal sample and the inhibited coal sample, and place them into heat treatment containers. Pass compressed air (oxygen content 21%) at a rate of 80mL / min. Simultaneously heat twelve heat treatment containers at a rate of 0.8℃ / min. Collect gas samples from the heat treatment containers at 100℃ and 180℃, and measure the CO gas volume fraction (%). Inhibition rate: Under the same conditions, the ratio of the difference in CO gas volume fraction between the raw coal sample and the inhibited coal sample to the CO gas volume fraction of the inhibited coal sample, calculated as follows:

[0037] E = (AB) × 100% / A;

[0038] In the formula: E is the inhibition rate, %; A is the volume fraction of CO gas in the raw coal sample, %; B is the volume fraction of CO gas in the inhibited coal sample, %.

[0039] The experimental results are shown in the table below.

[0040]

[0041] Since the interpenetrating polymer network (IPN) is composed of molecular chains entangled together, each network can exert its own adsorption capacity, resulting in a synergistic effect. Currently, the hydrophobicity or hydrophilicity of the polymer networks constituting IPNs reported in the literature is mostly similar or the same, and research reports on IPNs composed of hydrophobic and hydrophilic crosslinked polymers are scarce. The purpose of this invention is to prepare a liquid polymer inhibitor for coal mines using the above principle. The elastic recovery force generated when the molecular chains of the IPN networks are entangled can enhance the adhesion and barrier ability of the IPN polymer on the coal mine surface, thereby improving its inhibition rate and the duration of effectiveness at high temperatures. The test results show that the liquid polymer inhibitor for coal mines prepared in this invention has a high inhibition rate (the inhibition rate of conventional calcium chloride and / or magnesium chloride is about 50%), and still maintains a good inhibition effect at 180℃. In contrast, inhibitors using only hydrophilic polymers have poor inhibition effects and are prone to failure at high temperatures; inhibitors using only hydrophobic polymers have no inhibition effect.

[0042] Example 5 This example provides an application in a coal mine project.

[0043] The liquid polymer inhibitor #3 prepared in Example 3 has a boiling point range of less than 64.8°C during dissolution or deliquescence, does not spontaneously combust, has an inhibition rate of over 95%, is resistant to high temperatures, and can be mixed in a ratio of 1 to 30 times. When fire prevention, add 2.0% to 5.0% of this product, and when fire extinguishing, add 6.0% to 10.0% of this product.

[0044] Recommended dosage parameters for calculation, spray volume per application on the working surface:

[0045] The spraying volume per working face can be calculated using the following formula: V1=K1·K2·L·B·h1·A1 / g

[0046] In the formula:

[0047] V1 is calculated by volume for each application of floating coal, in kg;

[0048] K1—The dosage coefficient for the liquid in easily ignited parts, generally taken as 1.2;

[0049] K2 — Bulk density of loose coal in the goaf, (0.8-1.0) t / m³3 Take 1.0;

[0050] L—Length of the working face, (50-80)m, take 80;

[0051] B – Spray width per stroke, 0.8m;

[0052] h1—Thickness of floating coal on the bottom plate, 0.05m;

[0053] A1 – Liquid absorption capacity of the original floating coal (floating coal): 5 kg / t;

[0054] g — Density of inhibitor solution 1.05 t / m³ 2 .

[0055] Substitute into the formula:

[0056] V1=1.2×1.0×80×0.8×0.05×5 / 1.05=18.3kg;

[0057] Spray once a day during daily maintenance of the working face, with a spraying amount of no less than 18.3 kg each time.

[0058] (1) Drilling and grouting between and behind the working face:

[0059] The equipment utilizes mining-grade inhibition pumps, pneumatic inhibition pumps, grouting pumps, diaphragm pumps, screw pumps, plunger pumps, and mud pumps; or it can utilize a ground grouting system mixed with yellow mud slurry for pressure injection. As the working face advances, large-area coverage and inhibition of floating coal in the goaf are achieved through inter-frame and post-frame spraying, drilling, and pre-buried pipelines. The application process can be tailored to the mine's specific spraying techniques, such as spraying per frame or intermittent pressure injection. The material remains in a liquid state during preparation and use, without any heat generation process, exhibiting high heat absorption capacity, good cooling performance, and high fire prevention and extinguishing efficiency.

[0060] (2) Opening the incision and stopping the mining line:

[0061] The injection equipment can include mining inhibitor pumps, pneumatic inhibitor pumps, grouting pumps, diaphragm pumps, screw pumps, plunger pumps, and mud pumps; or a surface grouting system can be used to mix yellow mud slurry to seal the corresponding locations of the cut-off point or stop-mining line. The required injection volume can be adjusted according to the actual conditions of each mine. Based on the mine's experience, at a point 30 meters from the stop-mining line underground, a high-efficiency inhibitor is used to preventively inject the floating coal at the intake and return air ends and in the goaf as the working face advances, ensuring that the floating coal does not spontaneously combust and oxidize, thus providing a safety guarantee for the working face retreat.

[0062] (3) Spraying of floating coal at the upper and lower corners:

[0063] The oxygen-blocking extinguishing agent was injected into the upper and lower corners and the floating coal behind the frame.

[0064] In summary, during the trial use of the project, the liquid polymer inhibitor provided by this invention for coal mines showed an inhibition rate that was more than 30% higher than that of traditional inhibitors. Furthermore, the inhibitor of this invention has a longer inhibition lifespan, which is more than 30 days longer than that of traditional inhibitors (calcium chloride and / or magnesium chloride).

[0065] As described above, the basic principles, main features, and advantages of the present invention have been well described. The above embodiments and specifications are merely descriptions of preferred embodiments of the present invention, and the present invention is not limited to the above embodiments. Various changes and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit and scope of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A method for preparing a liquid polymer inhibitor for coal mines, characterized in that, include: Hydrophobic acrylate polymers are obtained by copolymerizing acrylate compounds; The hydrophobic acrylate polymer is placed in a solution containing a hydrophilic polymer precursor, a crosslinking agent, a surfactant, an antioxidant, and a solvent. After the reaction is heated, the mixture is cooled to room temperature to obtain the liquid polymer inhibitor. The hydrophilic polymer precursor is an epoxy compound; The epoxy compound is selected from at least one of glycidyl methacrylate, tetrahydrofurfuryl methacrylate, and 3,4-epoxycyclohexyl methacrylate. The crosslinking agent is selected from at least one of borax, epichlorohydrin, and toluene diisocyanate; The surfactant is selected from at least one of polyoxyethylene dehydrated sorbitan fatty acid ester, sulfobetaine, and lecithin; The antioxidant is a hindered phenolic antioxidant; The raw material consists of the following components in parts by weight: 100-300 parts of the hydrophobic acrylate polymer described above; 120-200 parts of the hydrophilic polymer precursor described above; 5-10 parts of the crosslinking agent described above; 1 to 10 parts of the surfactant described; 30-60 parts of the antioxidant described; 20 to 80 parts of the solvent.

2. The method for preparing the liquid polymer inhibitor for coal mines according to claim 1, characterized in that, The acrylate compound is selected from at least one of methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

3. The method for preparing the liquid polymer inhibitor for coal mines according to claim 1, characterized in that, The solvent is selected from at least one of methanol, ethanol, and butanol.

4. A liquid polymer inhibitor for use in coal mines, characterized in that, It is prepared by the method for preparing liquid polymer inhibitors for coal mines according to any one of claims 1 to 3.

5. The liquid polymer inhibitor for coal mines according to claim 4, characterized in that, The inhibition rate of the liquid polymer inhibitor used in coal mines is not less than 95%.

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