WO2022082949A1

WO2022082949A1 - Mussel bionic principle-based coal seam moistening method

Info

Publication number: WO2022082949A1
Application number: PCT/CN2020/134388
Authority: WO
Inventors: 赵艳云; 侯娇云; 胡相明; 邵志昂; 程卫民
Original assignee: 山东科技大学
Priority date: 2020-10-23
Filing date: 2020-12-08
Publication date: 2022-04-28
Also published as: CN112412523A

Abstract

A mussel bionic principle-based coal seam moistening method, which relates to the technical field of coal mine dust prevention. The raw material composition of a coal seam water injection wetting agent used in the method is as follows: dopamine, which is used for producing polydopamine by oxidative self-polymerization under a weak alkaline condition; polyacrylamide, which is used for carrying out hydrophilic secondary modification on the formed polydopamine; copper sulfate, which is used for increasing the speed at which polydopamine is produced by the oxidative self-polymerization of dopamine; hydrogen peroxide, which cooperates with the copper sulfate and is used for increasing the speed at which polydopamine is produced by the oxidative self-polymerization of dopamine; sodium hydroxide, which provides an alkaline environment for the solution, so that the pH value of the solution is 8.5-11; and water, water being used as a solvent. Dopamine passes through oxidative self-polymerization to become polydopamine, and the polydopamine and polyacrylamide are subjected to Michael addition and are cross-linked with one another. After the water injection wetting agent is injected into a coal seam, the hydrophilicity of the coal surface may be significantly improved.

Description

Coal seam enhancement method based on mussel bionic principle

technical field

The invention relates to the technical field of coal mine dust prevention, in particular to a coal seam moisturizing method based on the mussel bionic principle.

Background technique

In underground coal mines, suspended coal dust can cause coal miners' pneumoconiosis and coal mine explosion accidents. With the continuous improvement of the degree of mechanization of coal mining, the amount of dust produced in the coal mining process is also increasing. The total dust concentration of fully mechanized mining face can reach 1200-1500 mg/m ³ , and the concentration of inhalable dust usually exceeds 300 mg/m ³ . Due to long-term exposure to excessive coal dust, pneumoconiosis has become the most serious occupational disease among coal miners, and the number of patients with pneumoconiosis is increasing every year. Therefore, how to reduce the concentration of mine dust to protect the health of coal miners has always attracted people's attention.

At present, many technologies, such as water mist, scrubbers and water injection, have been developed to reduce the generation of dust in coal mining. Among them, coal seam water injection is an important means to reduce mine dust production, and it is also the only way to actively reduce dust production. measures. Coal seam water injection is the process of injecting liquid into the coal seam in front of the working face under a certain pressure. The liquid is injected into the coal seam along the cleats and cracks, and penetrates a considerable distance from the borehole in the radial direction, which can effectively achieve the effect of wetting and dust reduction. . However, due to the low surface free energy of coal and the poor water permeability of coal seam, the water injection wetting effect of coal seam has been to be improved. In the current research on water injection in coal seams, adding surfactants to water is a common method to improve the effect of water injection. Although this method can reduce the surface tension of water and thus improve the wetting effect of water injection, it will not be used in the subsequent coal injection. It is difficult to continue to play a role in the process of transportation and use.

In summary, although the existing technology has made certain progress in the research on the prevention and control of dust in coal mining, it still needs to be further improved to reduce the generation of coal dust.

technical solutions

The purpose of the present invention is to provide a coal seam moisturizing method based on the mussel bionic principle. Starting from the hydrophobicity of the coal, the water injection wetting agent can be injected into the coal body before the coal mining, so that the surface of the coal can be hydrophilized and modified, The coal surface is converted from hydrophobicity to hydrophilicity, which improves the water injection and wetting effect of the coal seam, thereby reducing the generation of coal dust.

In order to achieve the above object, the present invention adopts the following technical solutions:

A kind of coal seam moisturizing method based on mussel biomimetic principle, the coal seam water-injection wetting agent it adopts is composed of the following raw materials:

Dopamine is used for oxidative self-polymerization to generate polydopamine under weak alkaline conditions, and the concentration of the dopamine is 1-3 mg/mL;

Polyacrylamide, which is used for the secondary modification of hydrophilicity to the formed polydopamine, and the molar ratio of the polyacrylamide to the dopamine is 0.5 to 4:1;

Copper sulfate, used to improve the speed of the oxidation and self-polymerization of dopamine to generate polydopamine; the concentration of the copper sulfate is 4～8mmol/L;

Hydrogen peroxide, in conjunction with the copper sulfate, is used to improve the speed of the dopamine oxidation and self-polymerization to generate polydopamine; the concentration of the hydrogen peroxide is 19.6-29.4 mmol/L;

Sodium hydroxide, which provides an alkaline environment for the solution, so that the pH of the solution is 8.5 to 11;

And water, described water is used as solvent;

The described coal seam moisturizing method comprises the following steps:

Before coal mining, the coal seam water injection wetting agent is injected into the corresponding coal seam to change the hydrophobicity of the corresponding coal seam.

As a preferred solution of the present invention, the molar ratio of the polyacrylamide to the dopamine is 1:1.

As another preferred version of the present invention, the copper sulfate is copper sulfate pentahydrate, and the mass fraction of the hydrogen peroxide is 30%.

The preparation method of the above-mentioned coal seam water injection wetting agent comprises the following steps in turn:

S1. Adjust the pH of a certain volume of water to 8.5-11 with sodium hydroxide;

S2. Dissolve a certain amount of polyacrylamide in water with a pH of 8.5 to 11, and stir at a constant temperature of 50 to 60°C for 0.5 to 1.5 h until the polyacrylamide is completely dissolved to obtain solution one;

S3, a certain amount of dopamine is dissolved in solution one to obtain solution two;

S4, a certain amount of copper sulfate is added to the solution two to obtain solution three;

S5, adding a certain amount of hydrogen peroxide into the solution 3 to obtain a wetting agent for coal seam water injection.

In the above-mentioned preparation method of a wetting agent for coal seam water injection, in step S2, constant temperature stirring is performed at a temperature of 55° C. for 1 hour until the polyacrylamide is completely dissolved.

Below, the reaction mechanism of the raw material in the coal seam water injection wetting agent of the present invention is described as follows:

The raw materials used in the present invention are dopamine, polyacrylamide, copper sulfate, hydrogen peroxide, sodium hydroxide and water. Among them, dopamine and polyacrylamide are used as the main raw materials, and dopamine is a neurotransmitter endocrine in the brain of organisms. It can undergo oxidative self-polymerization under weak alkaline conditions to generate polydopamine. The molecular structure of this type of polymer contains functional groups such as catechol and primary amines, which have strong adhesion and good hydrophilicity, and can be easily deposited on on almost all types of inorganic and organic substrates, including superhydrophobic surfaces. The reaction process is simple and the conditions are mild, and the formed polydopamine coating has controllable film thickness and long-lasting stability, and has been widely used as a modified material in various fields. Since polydopamine molecules have rich physical and chemical properties, they can be modified by physical effects (such as hydrogen bonds, etc.) and chemical reactions (such as Michael addition reaction, etc.) The strong polyacrylamide performs hydrophilic secondary modification on the polydopamine coating, so that the coal modified by the coal seam water injection wetting agent has good wettability.

In the above-mentioned raw materials, the addition of copper sulfate and hydrogen peroxide is to improve the oxidative self-polymerization of dopamine and the deposition rate of polydopamine-polyacrylamide coating on the coal surface.

In the coal seam moisturizing method based on the mussel biomimetic principle, dopamine is oxidized and self-polymerized into polydopamine, and then the Michael addition reaction occurs between polydopamine and polyacrylamide, and the two are cross-linked with each other. After this coal seam water-injection wetting agent is injected into the coal seam, the polydopamine-polyacrylamide adheres to the coal surface to form a coating due to the non-covalent interaction between the polydopamine and the coal surface. A large number of amino groups, hydroxyl groups and amide groups can significantly improve the hydrophilicity of the coal surface.

beneficial effect

Compared with the prior art, the present invention brings the following beneficial technical effects:

(1) Different from the previous method of reducing the surface tension of water to improve the wetting effect of coal seam water injection, the present invention takes the hydrophobicity of coal as the starting point, and performs hydrophilic modification on it, so as to improve the water injection and wetting effect of coal seam .

(2) Before coal mining, the coal seam water-injection wetting agent is injected into the coal seam by means of water-injection, so as to make the coal hydrophilic and modified. Good wettability has been maintained during transportation and use to reduce coal dust production from start to finish.

(3) The wetting agent for coal seam water injection prepared by using hydrophilic modified material polydopamine and superabsorbent resin polyacrylamide has good hydrophilicity.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings:

Fig. 1 is the mechanism diagram of the deposition of polydopamine-polyacrylamide coating on the coal surface according to the embodiment of the present invention;

2 is a schematic diagram of a contact angle of an embodiment of the present invention;

Fig. 3 is the variation situation of contact angle with time when the embodiment of the present invention changes the concentration of dopamine;

4 is the variation of the contact angle with time when the deposition time is changed in the embodiment of the present invention;

Fig. 5 is the variation of the contact angle with time when the molar ratio of polyacrylamide and dopamine added is changed in the embodiment of the present invention.

Embodiments of the present invention

The present invention proposes a coal seam moisturizing method based on the mussel bionic principle. In order to make the advantages and technical solutions of the present invention clearer and clearer, the present invention is described in detail below with reference to specific embodiments.

The used briquettes of the following examples are all pressed as follows:

The briquettes were compressed with a 769YP-24B tablet press produced by Shanghai Xinnuo Instrument Co., Ltd. 550 mg of pulverized coal was weighed and added to the mold. Put the mold loaded with pulverized coal under the pressurizing machine, pressurize it to 20MPa, and take out the coal cake after maintaining the pressure for 2min. A certain number of briquettes with a diameter of about 1 cm and a thickness of about 5 mm are pressed.

In the following examples, the contact angle experiment was used to characterize the wetting effect of the coal surface.

Contact angle is an important parameter to evaluate the wettability of liquid on solid. It refers to the angle θ between the tangent of the gas-liquid interface made at the intersection of the gas-liquid-solid three-phase and the solid-liquid interface on the side where the liquid is located, as shown in Figure 2. Show. The contact angle of the liquid on the coal surface is an important parameter to measure the wettability of the coal surface. The better the wetting effect, the smaller the contact angle, and the easier the solution is to diffuse on the solid surface. It is generally believed that when θ < 90°, the solid surface is hydrophilic, and the liquid is more likely to wet the solid, and the smaller the θ value, the better the wettability.

In the following examples, mM refers to millimoles per liter.

Figure 1 shows the reaction mechanism of the present invention, in which polydopamine is mainly generated by oxidative self-polymerization of dopamine under weak alkaline conditions, and then the polydopamine coating is subjected to hydrophilic secondary modification by polyacrylamide, so that the polydopamine coating is hydrophilic. The coal modified by the water injection wetting agent in the coal seam has good wettability.

Example 1:

Four groups of coal seam water-injection wetting agents with different dopamine concentrations were set, and the dopamine concentrations were set to 0, 1 mg/mL, 2 mg/mL, and 3 mg/mL, respectively. At this time, polyacrylamide was added at a molar ratio of 1:1 to dopamine. , the copper sulfate concentration was 5.3 mM, and the hydrogen peroxide concentration was 26.1 mM. The preparation process of the wetting agent for coal seam water injection is as described in the Summary of the Invention. The prepared briquettes were placed in four prepared coal seam water-injection wetting agents with different concentrations of dopamine, deposited for 30 minutes, and then the briquettes were taken out and dried, and then the contact angle experiment was carried out. The experimental results are shown in Figure 3.

It can be seen from Figure 3 that the contact angle of the raw coal used in the experiment is about 70°, and the change of the contact angle with time is small. Compared with the original coal sample, the change rate of the contact angle with time is greatly accelerated. It can be seen that this modification method can significantly improve the wetting effect of the coal sample surface. And it can be seen from the figure that the dopamine concentration in the coal seam water injection wetting agent is different, and the contact angle of the modified coal cake is not much different. The optimum concentration is 2 mg/mL.

Example 2:

Set five different deposition times, respectively 0, 15min, 30min, 45min, 60min. At this time, the concentration of dopamine is 2 mg/mL, polyacrylamide and dopamine are added in a molar ratio of 1:1, and the concentration of copper sulfate was 5.3 mM and the hydrogen peroxide concentration was 26.1 mM. The preparation process of the wetting agent for coal seam water injection is as described in the Summary of the Invention. The prepared coal briquettes were placed in the prepared coal seam water-injection wetting agent, deposited and modified according to five groups of time gradients, then the coal briquettes were taken out and dried, and then the contact angle experiment was carried out. The experimental results are shown in Figure 4.

It can be seen from Fig. 4 that the contact angle of the coal sample is significantly reduced after the deposition and modification of the coal seam water injection wetting agent. When the deposition time is 15min, the contact angle of the coal sample surface is about 35° at 10s, and when the deposition time increases to 30min, the contact angle decreased significantly. When the deposition time continued to increase to 45min and 60min, the contact angle changed little, and the change rate of the contact angle with time was similar under the four deposition time conditions. Therefore, considering the convenience in practical application, the optimal deposition time is 30 min.

Example 3:

Five groups of different molar ratios of polyacrylamide and dopamine dosing are set, and the molar ratios of polyacrylamide and dopamine dosing are set as 0:1, 0.5:1, 1:1, 2:1, 4:1 respectively. Dopamine was 2 mg/mL, copper sulfate concentration was 5.3 mM, and hydrogen peroxide concentration was 26.1 mM. The coal briquettes were placed in five groups of coal seam water-flooding wetting agents with different dosing ratios of polyacrylamide and dopamine. After deposition for 30 min, the briquettes were taken out and dried, and then the contact angle experiment was carried out. The experimental results are shown in Figure 5. .

It can be seen from Fig. 5 that, compared with the coal samples modified by pure dopamine solution, the contact angles of coal samples modified by water-flooding wetting agent with four different dosage ratios of polyacrylamide and dopamine have a relatively obvious decrease. And with the increase of polyacrylamide concentration, the overall change trend of the contact angle is to decrease first and then increase. When the dosage ratio of polyacrylamide and dopamine is 1:1, the obtained contact angle is the smallest, and the rate of change with time is fast, so the optimal dosage ratio of polyacrylamide and dopamine is 1:1.

Through the above three embodiments, it can be seen that this method of coal seam water injection wetting agent modification can significantly reduce the contact angle of the coal surface, that is, improve the wettability of the coal surface, and the optimized modification conditions can be obtained as follows: The dopamine concentration was 2 mg/mL, the deposition time was 30 min, and the molar ratio of polyacrylamide to dopamine was 1:1.

The parts not mentioned in the present invention can be realized by referring to the prior art.

It should be noted that any equivalent manner or obvious modification manner made by those skilled in the art under the teaching of this specification shall fall within the protection scope of the present invention.

Claims

A kind of coal seam moisturizing method based on mussel bionic principle, is characterized in that, the coal seam water-injection wetting agent that it adopts is made up of following raw materials:

Dopamine is used for oxidative self-polymerization to generate polydopamine under weak alkaline conditions, and the concentration of the dopamine is 1-3 mg/mL;

Polyacrylamide, which is used for the secondary modification of hydrophilicity to the formed polydopamine, and the molar ratio of the polyacrylamide to the dopamine is 0.5 to 4:1;

Copper sulfate, used to improve the speed of the oxidation and self-polymerization of dopamine to generate polydopamine; the concentration of the copper sulfate is 4～8mmol/L;

Hydrogen peroxide, in conjunction with the copper sulfate, is used to improve the speed of the dopamine oxidation and self-polymerization to generate polydopamine; the concentration of the hydrogen peroxide is 19.6-29.4 mmol/L;

Sodium hydroxide, which provides an alkaline environment for the solution, so that the pH of the solution is 8.5 to 11;

And water, described water is used as solvent;

The described coal seam moisturizing method comprises the following steps:

Before coal mining, the coal seam water injection wetting agent is injected into the corresponding coal seam to change the hydrophobicity of the corresponding coal seam.
A coal seam moisturizing method based on mussel biomimetic principle according to claim 1, characterized in that: the molar ratio of the polyacrylamide to the dopamine is 1:1.
A kind of coal seam moisturizing method based on mussel bionic principle according to claim 1, is characterized in that: described copper sulfate is copper sulfate pentahydrate, and the mass fraction of described hydrogen peroxide is 30%.
The coal seam moisturizing method based on the mussel bionic principle according to any one of claims 1 to 3, wherein the preparation method of the coal seam water injection wetting agent comprises the following steps in sequence:

S1. Adjust the pH of a certain volume of water to 8.5-11 with sodium hydroxide;

S2. Dissolve a certain amount of polyacrylamide in water with a pH of 8.5 to 11, and stir at a constant temperature of 50 to 60°C for 0.5 to 1.5 h until the polyacrylamide is completely dissolved to obtain solution one;

S3, a certain amount of dopamine is dissolved in solution one to obtain solution two;

S4, a certain amount of copper sulfate is added to the solution two to obtain solution three;

S5, adding a certain amount of hydrogen peroxide into the solution 3 to obtain a wetting agent for coal seam water injection.
A coal seam moisturizing method based on the mussel bionic principle according to claim 4, characterized in that: in step S2, constant temperature stirring is performed at a temperature of 55° C. for 1 h until the polyacrylamide is completely dissolved.