Waterproof dust suppressant for coal and preparation method of waterproof dust suppressant

Abstract

The invention discloses a waterproof dust suppressant for coal and a preparation method of the waterproof dust suppressant. Comprising the following steps: step 1, dispersing sodium alginate and sodium carboxymethyl cellulose in deionized water, stirring in a water bath at 50 DEG C, adding ammonium persulfate, then adding modified silicon dioxide, N, N '-methylene bisacrylamide and acrylamide, and raising the temperature to react to obtain a copolymer solution; step 2, mixing the copolymer solution, sodium dodecyl benzene sulfonate and carboxymethyl chitosan to obtain the waterproof dust suppressant. The preparation method has the beneficial effects that silicon dioxide is chemically modified, active groups are introduced to the surface of the silicon dioxide, and the crosslinking effect of the silicon dioxide and a high polymer material is remarkably enhanced, so that the mechanical strength and compactness of a dust suppressant curing layer are improved; and moreover, the introduction of hydrophobic groups on the surface enhances the waterproof performance. Meanwhile, due to the synergistic effect of the modified silicon dioxide, carboxymethyl chitosan and other components, the wind erosion resistance and water erosion resistance of the dust suppressant are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of dust suppressants, and in particular relates to a waterproof dust suppressant for coal and a preparation method thereof. Background Art

[0002] During coal mining, transportation and storage, coal dust is easily affected by wind or mechanical action to generate dust, which not only wastes resources, but also seriously pollutes the environment and harms human health. At present, commonly used dust suppression technologies include sprinkling water, covering dust-proof nets or spraying chemical dust suppressants. Among them, chemical dust suppressants have attracted widespread attention due to their convenience of use and long-lasting effect.

[0003] However, existing dust suppressants still have many defects: first, traditional dust suppressants (such as ordinary polymer emulsions or surfactants) have poor waterproof properties, are easily dissolved or washed away by water, and are difficult to adapt to humid or rainy environments such as open-air coal yards; second, physical adsorption dust suppressants (such as silica or clay) have weak binding force with coal powder, insufficient wind erosion resistance, and are easily detached due to wind force after long-term use; in addition, some dust suppressants rely on high-cost raw materials (such as silicone or fluorocarbon compounds), have poor economic efficiency, and are difficult to promote on a large scale. More importantly, nanomaterials such as silica in the existing technology are often difficult to form stable crosslinks with the polymer matrix due to surface inertia, resulting in insufficient mechanical strength of the dust suppression layer, which is easy to crack or peel off.

[0004] Therefore, in order to solve the above problems, the present invention provides a waterproof dust suppressant for coal and a preparation method thereof. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a waterproof dust suppressant for coal and a preparation method thereof.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for preparing a waterproof dust suppressant for coal comprises the following steps:

[0008] Step 1: Disperse sodium alginate and sodium carboxymethyl cellulose in deionized water, stir in a 50°C water bath, add ammonium persulfate, then add modified silica, N,N'-methylenebisacrylamide, and acrylamide, raise the temperature to 60-70°C, react for 1-2 hours, and cool to room temperature to obtain a copolymer solution;

[0009] Step 2: Mix the copolymer solution, sodium dodecylbenzene sulfonate and carboxymethyl chitosan to obtain a waterproof dust suppressant.

[0010] Preferably, the raw materials in the copolymer solution include the following components: by weight, 2-3 parts of sodium alginate, 0.3-0.5 parts of sodium carboxymethyl cellulose, 100-120 parts of deionized water, 0.1-0.3 parts of ammonium persulfate, 1-2 parts of modified silica, 2-4 parts of acrylamide, 0.03-0.06 parts of N,N'-methylenebisacrylamide;

[0011] The raw materials of the waterproof and dust suppressant include the following components: by weight, 100-120 parts of copolymer solution, 0.1-0.5 parts of sodium dodecylbenzenesulfonate, 1-3 parts of carboxymethyl chitosan.

[0012] Preferably, the preparation process of the modified silica is as follows:

[0013] S1: Mix nano-silica, toluene, and petroleum ether, raise the temperature to 90-100 °C, reflux for 1-2 h, then add dibutyltin dilaurate, and under a protective atmosphere, dropwise add toluene diisocyanate and react for 1-2 h. Centrifuge and filter, and dry in vacuum to obtain isocyanated silica;

[0014] S2: Under a protective atmosphere, mix 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, allylglycine, triethylamine, N,N-diisopropylcarbodiimide, and anhydrous dichloromethane, and react at room temperature for 3-4 h. After the reaction, extract with distilled water, take the organic layer, dry, filter, and rotary evaporate to obtain intermediate A;

[0015] S3: Under a protective atmosphere, add intermediate A to tetrahydrofuran, cool to 0 °C in an ice bath, then slowly dropwise add oxalyl chloride and N,N-dimethylformamide, gradually raise the temperature to room temperature and stir for 2-4 h. Distill off the solvent under reduced pressure, then mix with melamine, triethylamine, and dimethyl sulfoxide, and stir and react at 0 °C for 1-2 h. After the reaction, wash with water to remove inorganic salts, dry the organic phase, concentrate, and purify to obtain the modifier;

[0016] S4: Disperse isocyanated silica in dimethylformamide, add the modifier and triethylamine, raise the temperature to 70-80 °C, react for 1-3 h. After the reaction, cool to room temperature, filter, wash, and dry to obtain modified silica.

[0017] In the scheme, a large number of hydroxyl groups (Si-OH) exist on the surface of nano-silica, and react with the isocyanate groups (-NCO) of toluene diisocyanate (TDI) at high temperature (90-100 °C) to form urethane bonds. At the same time, the surface of nano-silica also contains isocyanate groups.

[0018] In the solution, 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid (containing a carboxylic acid group) and allylglycine (containing an amino group) undergo an amidation reaction under the action of a condensing agent (N,N-diisopropylcarbodiimide, DIC) and a base (triethylamine). The specific reaction process is as follows:

[0019]

[0020] In the solution, the carboxylic acid group of intermediate A is converted into an acyl chloride under the action of oxalyl chloride (Cl-CO-CO-Cl) and a catalytic amount of DMF. Then, the acyl chloride reacts with the amino group of melamine at low temperature (0 °C) to form an amide bond. The specific reaction process is as follows:

[0021]

[0022] In the solution, the amino group in the modifier reacts with the -NCO group on the surface of isocyanato-functionalized silica to obtain modified silica.

[0023] More preferably, the isocyanato-functionalized silica raw material comprises the following components: by weight, 10 - 12 parts of nano-silica, 200 - 250 parts of toluene, 100 - 150 parts of petroleum ether, 0.5 - 1 part of dibutyltin dilaurate, and 15 - 20 parts of toluene diisocyanate.

[0024] More preferably, the intermediate A raw material comprises the following components: by weight, 10 - 12 parts of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 6 - 7 parts of allylglycine, 8 - 10 parts of triethylamine, 8 - 10 parts of N,N-diisopropylcarbodiimide, and 200 - 300 parts of anhydrous dichloromethane.

[0025] More preferably, the modifier raw material comprises the following components: by weight, 10 - 12 parts of intermediate A, 150 - 200 parts of tetrahydrofuran, 15 - 20 parts of oxalyl chloride, 0.1 - 0.2 part of N,N-dimethylformamide, 3 - 4 parts of melamine, 5 - 7 parts of triethylamine, and 150 - 200 parts of dimethyl sulfoxide.

[0026] More preferably, the modified silica raw material comprises the following components: by weight, 10 - 12 parts of isocyanato-functionalized silica, 8 - 10 parts of modifier, 0.5 - 1 part of triethylamine, and 200 - 250 parts of N,N-dimethylformamide.

[0027] Advantages of the present invention:

[0028] The present invention chemically modifies silica to introduce reactive groups on its surface, significantly enhancing the cross-linking effect between silica and polymer materials (such as sodium alginate, acrylamide, etc.). This modified silica participates in the formation of the copolymer network as a cross-linking agent, not only improving the mechanical strength and compactness of the dust suppressant curing layer, but also enhancing the waterproof performance by introducing hydrophobic groups on its surface. At the same time, the modified silica and components such as carboxymethyl chitosan act synergistically to further improve the wind erosion resistance and water erosion resistance of the dust suppressant, as follows:

[0029] First: The antioxidant groups (such as hindered phenol structure) introduced on the surface of the modified silica can capture free radicals, interrupt the oxidation chain reaction, and inhibit the degradation of polymer materials (such as sodium alginate and acrylamide copolymer) under the action of high temperature, light, or environmental oxygen, thereby prolonging the service life of the dust suppressant curing layer; moreover, in the outdoor environment, the antioxidant groups can resist the photooxidation reaction induced by ultraviolet rays (UV), prevent the curing layer from embrittling or cracking due to long-term exposure to sunlight, and ensure the long-term effectiveness of the dust suppressant in scenarios such as open coal yards;

[0030] Second: The double bonds grafted on the surface of the modified silica can undergo free radical copolymerization reactions with monomers such as acrylamide under the action of ammonium persulfate initiator to form stable chemical cross-linking points. The nano-silica is firmly anchored in the polymer network through covalent bonding, effectively avoiding problems such as uneven dispersion or particle migration caused by traditional physical adsorption.

[0031] The introduction of double bonds significantly enhances the interfacial bonding force between silica and the polymer matrix. When the curing layer is subjected to external forces such as wind erosion and water erosion, the stress can be efficiently transmitted through the chemical bond network, reducing cracking or peeling phenomena caused by local stress concentration. In addition, long-chain hydrophobic groups such as lauric acid grafted on the surface of the modified silica undergo directional migration during the cross-linking process and accumulate on the surface of the curing layer to form a dense hydrophobic barrier, significantly reducing the contact area between water molecules and the curing layer by lowering the surface energy. At the same time, the cross-linking network physically encapsulates the pulverized coal particles, combined with the chemical bonding mechanism involving double bonds, greatly enhancing the interfacial adhesion strength between the particles and the curing layer, thereby effectively inhibiting secondary dust generation caused by wind disturbance or mechanical action. Detailed implementation mode

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0033] Example 1: A preparation method of a waterproof and dust - suppressing agent for coal, comprising the following steps:

[0034] Step 1: Disperse 2 parts of sodium alginate and 0.3 part of sodium carboxymethyl cellulose in 100 parts of deionized water, stir in a water bath at 50 °C, add 0.1 part of ammonium persulfate, then add 1 part of modified silica, 0.03 part of N,N'-methylenebisacrylamide, and 2 parts of acrylamide. Raise the temperature to 60 °C, react for 1 h, and cool to room temperature to obtain a copolymer solution;

[0035] Step 2: Mix 100 parts of the copolymer solution, 0.1 part of sodium dodecylbenzenesulfonate, and 1 part of carboxymethyl chitosan to obtain a waterproof and dust - suppressing agent;

[0036] Among them, the preparation process of the modified silica is as follows:

[0037] S1: Mix 10 parts of nano - silica, 200 parts of toluene, and 100 parts of petroleum ether, raise the temperature to 90 °C, reflux and react for 1 h. Then add 0.5 part of dibutyltin dilaurate, and under a protective atmosphere, drop - wise add 15 parts of toluene diisocyanate, react for 1 h, centrifuge and filter, and vacuum - dry to obtain isocyanato - modified silica;

[0038] S2: Under a protective atmosphere, mix 10 parts of 3,5 - di - tert - butyl - 4 - hydroxyphenylpropionic acid, 6 parts of allylglycine, 8 parts of triethylamine, 8 parts of N,N - diisopropylcarbodiimide, and 200 parts of anhydrous dichloromethane, react at room temperature for 3 h. After the reaction, extract with distilled water, take the organic layer, dry, filter, and rotary - evaporate to obtain intermediate A;

[0039] S3: Under a protective atmosphere, add 10 parts of intermediate A to 150 parts of tetrahydrofuran, cool to 0 °C in an ice bath, then slowly drop - wise add 15 parts of oxalyl chloride and 0.1 part of N,N - dimethylformamide, gradually raise the temperature to room temperature and stir for 2 h. Distill off the solvent under reduced pressure, then mix with 3 parts of melamine, 5 parts of triethylamine, and 150 parts of dimethyl sulfoxide, stir and react at 0 °C for 1 h. After the reaction, wash with water to remove inorganic salts, dry the organic phase, concentrate, and purify to obtain a modifier;

[0040] S4: Disperse 10 parts of isocyanato - modified silica in 200 parts of dimethylformamide, add 8 parts of the modifier and 0.5 part of triethylamine, raise the temperature to 70 °C, react for 1 h. After the reaction, cool to room temperature, filter, wash, and dry to obtain modified silica.

[0041] Example 2: A preparation method of a waterproof and dust - suppressing agent for coal, comprising the following steps:

[0042] Step 1: Disperse 3 parts of sodium alginate and 0.5 part of sodium carboxymethyl cellulose in 120 parts of deionized water, stir in a 50°C water bath, add 0.3 part of ammonium persulfate, then add 2 parts of modified silica, 0.06 part of N,N'-methylenebisacrylamide, and 4 parts of acrylamide. Raise the temperature to 70°C and react for 2 h. Cool to room temperature to obtain a copolymer solution;

[0043] Step 2: Mix 120 parts of the copolymer solution, 0.5 part of sodium dodecylbenzenesulfonate, and 3 parts of carboxymethyl chitosan to obtain a waterproof and dust suppressant;

[0044] Among them, the preparation process of the modified silica is as follows:

[0045] S1: Mix 12 parts of nano-silica, 250 parts of toluene, and 150 parts of petroleum ether, raise the temperature to 100°C, reflux and react for 2 h. Then add 1 part of dibutyltin dilaurate, and under a protective atmosphere, dropwise add 20 parts of toluene diisocyanate and react for 2 h. Centrifuge and filter, and vacuum dry to obtain isocyanated silica;

[0046] S2: Under a protective atmosphere, mix 12 parts of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 7 parts of allylglycine, 10 parts of triethylamine, 10 parts of N,N-diisopropylcarbodiimide, and 300 parts of anhydrous dichloromethane, and react at room temperature for 4 h. After the reaction, extract with distilled water, take the organic layer, dry, filter, and rotary evaporate to obtain intermediate A;

[0047] S3: Under a protective atmosphere, add 12 parts of intermediate A to 200 parts of tetrahydrofuran, cool to 0°C in an ice bath, then slowly dropwise add 20 parts of oxalyl chloride and 0.2 part of N,N-dimethylformamide, gradually raise the temperature to room temperature and stir for 4 h. Distill off the solvent under reduced pressure, then mix with 4 parts of melamine, 7 parts of triethylamine, and 200 parts of dimethyl sulfoxide, and stir and react at 0°C for 2 h. After the reaction, wash with water to remove inorganic salts, dry the organic phase, concentrate, and purify to obtain a modifier;

[0048] S4: Disperse 12 parts of isocyanated silica in 250 parts of dimethylformamide, add 10 parts of the modifier and 1 part of triethylamine, raise the temperature to 80°C, and react for 3 h. After the reaction, cool to room temperature, filter, wash, and dry to obtain modified silica.

[0049] Example 3: A preparation method of a waterproof and dust suppressant for coal, comprising the following steps:

[0050] Step 1: Disperse 2.5 parts of sodium alginate and 0.4 part of sodium carboxymethyl cellulose in 110 parts of deionized water, stir in a water bath at 50 °C, add 0.2 part of ammonium persulfate, then add 1.5 parts of modified silica, 0.045 part of N,N'-methylenebisacrylamide, and 3 parts of acrylamide. Raise the temperature to 65 °C and react for 1.5 h. Cool to room temperature to obtain a copolymer solution;

[0051] Step 2: Mix 110 parts of the copolymer solution, 0.3 part of sodium dodecylbenzenesulfonate, and 2 parts of carboxymethyl chitosan to obtain a waterproof and dust suppressant;

[0052] Among them, the preparation process of the modified silica is as follows:

[0053] S1: Mix 11 parts of nano-silica, 225 parts of toluene, and 125 parts of petroleum ether, raise the temperature to 95 °C, reflux and react for 1.5 h. Then add 0.75 part of dibutyltin dilaurate, and under a protective atmosphere, dropwise add 17.5 parts of toluene diisocyanate and react for 1.5 h. Centrifuge and filter, and vacuum dry to obtain isocyanated silica;

[0054] S2: Under a protective atmosphere, mix 11 parts of 3,5-ditert-butyl-4-hydroxyphenylpropionic acid, 6.5 parts of allylglycine, 9 parts of triethylamine, 9 parts of N,N-diisopropylcarbodiimide, and 250 parts of anhydrous dichloromethane, and react at room temperature for 3.5 h. After the reaction, extract with distilled water, take the organic layer, dry, filter, and rotary evaporate to obtain intermediate A;

[0055] S3: Under a protective atmosphere, add 11 parts of intermediate A to 175 parts of tetrahydrofuran, cool to 0 °C in an ice bath, then slowly dropwise add 17.5 parts of oxalyl chloride and 0.15 part of N,N-dimethylformamide, gradually raise the temperature to room temperature and stir for 3 h. Distill off the solvent under reduced pressure, then mix with 3.5 parts of melamine, 6 parts of triethylamine, and 175 parts of dimethyl sulfoxide, and stir and react at 0 °C for 1.5 h. After the reaction, wash with water to remove inorganic salts, dry the organic phase, concentrate, and purify to obtain a modifier;

[0056] S4: Disperse 11 parts of isocyanated silica in 225 parts of dimethylformamide, add 9 parts of the modifier and 0.75 part of triethylamine, raise the temperature to 75 °C, and react for 2 h. After the reaction, cool to room temperature, filter, wash, and dry to obtain modified silica.

[0057] Comparative Example 1: Do not add modified silica, and the rest is the same as in Example 3, specifically as follows:

[0058] Step 1: Disperse 2.5 parts of sodium alginate and 0.4 part of sodium carboxymethyl cellulose in 110 parts of deionized water, stir in a water bath at 50 °C, add 0.2 part of ammonium persulfate, then add 0.045 part of N,N'-methylenebisacrylamide and 3 parts of acrylamide, raise the temperature to 65 °C, react for 1.5 h, and cool to room temperature to obtain a copolymer solution;

[0059] Step 2: Mix 110 parts of the copolymer solution, 0.3 part of sodium dodecylbenzenesulfonate, and 2 parts of carboxymethyl chitosan to obtain a waterproof and dust suppressant.

[0060] Comparative Example 2: Do not modify silicon dioxide, and the rest is the same as in Example 3. Specifically as follows:

[0061] Step 1: Disperse 2.5 parts of sodium alginate and 0.4 part of sodium carboxymethyl cellulose in 110 parts of deionized water, stir in a water bath at 50 °C, add 0.2 part of ammonium persulfate, then add 1.5 parts of nano-silicon dioxide, 0.045 part of N,N'-methylenebisacrylamide, and 3 parts of acrylamide, raise the temperature to 65 °C, react for 1.5 h, and cool to room temperature to obtain a copolymer solution;

[0062] Step 2: Mix 110 parts of the copolymer solution, 0.3 part of sodium dodecylbenzenesulfonate, and 2 parts of carboxymethyl chitosan to obtain a waterproof and dust suppressant.

[0063] Detection experiment: Spray the waterproof and dust suppressants obtained in the examples and comparative examples on the surface of pulverized coal (pulverized coal mass 140 ± 0.1 g, particle size 300 - 400 mesh), and naturally dry to form a cured layer; then conduct relevant detections;

[0064] (1) Use a pressure gauge probe to vertically act on the surface of the cured layer, apply pressure at a constant rate (such as 1 mm / min) until the cured layer breaks, and record the maximum pressure value;

[0065] (2) Blow the obtained cured layer at a wind speed of 12 m / s for 20 minutes, record the mass difference before and after, and use it to calculate the mass loss rate;

[0066] (3) Place the obtained cured layer under a faucet, let the water flow over the surface of the coal tray sample at a flow rate of 36 L / h for 2 minutes, then take it out, dry it, weigh the mass before and after twice, and calculate the water erosion rate;

[0067] The data obtained are shown in the following table:

[0068]

[0069] Table 1

[0070] Conclusion: By chemically modifying silica, the present invention significantly improves the performance of the waterproof and dust suppressant for coal. Experimental data show that Examples 1, 2, and 3 with the addition of modified silica are superior to Comparative Example 1 without the addition of modified silica (pressure value 43 N, wind erosion rate 7.5%, water erosion rate 6.8%) and Comparative Example 2 using only unmodified silica (pressure value 46 N, wind erosion rate 4.6%, water erosion rate 5.7%) in terms of pressure value (50 - 56 N), wind erosion rate (0.25% - 0.31%), and water erosion rate (2.2% - 2.6%). The modified silica significantly improves the mechanical strength, wind erosion resistance, and waterproof performance of the dust suppressant by enhancing cross-linking, introducing antioxidant groups and hydrophobic groups, effectively suppressing the secondary dusting of coal powder and water erosion loss, and verifying its excellent effect in the field of coal dust suppression.

[0071] In the description of the specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0072] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should fall within the protection scope of the present invention.

Claims

1. A preparation method of a waterproof and dust suppressant for coal, characterized in that: It includes the following steps: Step 1: Dissolve sodium alginate and sodium carboxymethylcellulose in deionized water, stir in a water bath at 50 °C, add ammonium persulfate, then add modified silica, N,N'-methylenebisacrylamide, and acrylamide, raise the temperature to 60 - 70 °C, react for 1 - 2 h, and cool to room temperature to obtain a copolymer solution; Step 2: Mix the copolymer solution, sodium dodecylbenzenesulfonate, and carboxymethyl chitosan to obtain a waterproof and dust suppressant.

2. The preparation method of a waterproof and dust suppressant for coal according to claim 1, characterized in that: The raw materials in the copolymer solution include the following components: by weight, 2 - 3 parts of sodium alginate, 0.3 - 0.5 parts of sodium carboxymethylcellulose, 100 - 120 parts of deionized water, 0.1 - 0.3 parts of ammonium persulfate, 1 - 2 parts of modified silica, 2 - 4 parts of acrylamide, 0.03 - 0.06 parts of N,N'-methylenebisacrylamide; The raw materials of the waterproof and dust suppressant include the following components: by weight, 100 - 120 parts of copolymer solution, 0.1 - 0.5 parts of sodium dodecylbenzenesulfonate, 1 - 3 parts of carboxymethyl chitosan.

3. The preparation method of a waterproof and dust suppressant for coal according to claim 1, characterized in that: The preparation process of the modified silica is as follows: S1: Mix nano-silica, toluene, and petroleum ether, raise the temperature to 90 - 100 °C, reflux and react for 1 - 2 h, then add dibutyltin dilaurate, under a protective atmosphere, dropwise add toluene diisocyanate, react for 1 - 2 h, centrifuge and filter, and vacuum dry to obtain isocyanato-functionalized silica; S2: Under a protective atmosphere, mix 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, allylglycine, triethylamine, N,N-diisopropylcarbodiimide, and anhydrous dichloromethane, react at room temperature for 3 - 4 h, after the reaction, extract with distilled water, take the organic layer, dry, filter, and rotary evaporate to obtain intermediate A; S3: Under a protective atmosphere, add intermediate A to tetrahydrofuran, cool to 0 °C in an ice bath, then slowly dropwise add oxalyl chloride and N,N-dimethylformamide, gradually raise the temperature to room temperature and stir for 2 - 4 h, distill off the solvent under reduced pressure, then mix with melamine, triethylamine, and dimethyl sulfoxide, stir and react at 0 °C for 1 - 2 h, after the reaction, wash with water to remove inorganic salts, dry the organic phase, concentrate, and purify to obtain a modifier; S4: Disperse isocyanato-functionalized silica in dimethylformamide, add the modifier and triethylamine, raise the temperature to 70 - 80 °C, react for 1 - 3 h, after the reaction, cool to room temperature, filter, wash, and dry to obtain modified silica.

4. The preparation method of a waterproof and dust suppressant for coal according to claim 3, wherein: The raw materials of the isocyanato-functionalized silica include the following components: by weight, 10 - 12 parts of nano-silica, 200 - 250 parts of toluene, 100 - 150 parts of petroleum ether, 0.5 - 1 part of dibutyltin dilaurate, 15 - 20 parts of toluene diisocyanate.

5. The preparation method of a waterproof and dust suppressant for coal according to claim 3, characterized in that: The raw materials of intermediate A include the following components: by weight, 10 - 12 parts of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid, 6 - 7 parts of allylglycine, 8 - 10 parts of triethylamine, 8 - 10 parts of N,N-diisopropylcarbodiimide, 200 - 300 parts of anhydrous dichloromethane.

6. The preparation method of a waterproof and dust suppressant for coal according to claim 3, characterized in that: The modifier raw materials include the following components: by weight, 10 - 12 parts of intermediate A, 150 - 200 parts of tetrahydrofuran, 15 - 20 parts of oxalyl chloride, 0.1 - 0.2 parts of N,N - dimethylformamide, 3 - 4 parts of melamine, 5 - 7 parts of triethylamine, and 150 - 200 parts of dimethyl sulfoxide.

7. The preparation method of a waterproof and dust suppressant for coal according to claim 3, characterized in that: The modified silica raw materials include the following components: by weight, 10 - 12 parts of isocyanated silica, 8 - 10 parts of modifier, 0.5 - 1 part of triethylamine, and 200 - 250 parts of N,N - dimethylformamide.

8. The waterproof and dust - suppressing agent obtained by the preparation method of a waterproof and dust - suppressing agent for coal according to any one of claims 1 - 7.

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