CN115245646B

CN115245646B - Coal mine goaf fire prevention and extinguishment composite material and preparation method thereof

Info

Publication number: CN115245646B
Application number: CN202210000980.XA
Authority: CN
Inventors: 郝宇; 张立辉; 赵利群
Original assignee: Chongqing Vocational Institute of Engineering
Current assignee: Chongqing Vocational Institute of Engineering
Priority date: 2022-01-04
Filing date: 2022-01-04
Publication date: 2023-07-04
Anticipated expiration: 2042-01-04
Also published as: CN115245646A

Abstract

The invention discloses a coal mine goaf fire prevention and extinguishing composite material which is prepared from the following raw materials in parts by weight: 2-3 parts of sodium alginate, 1.2-1.6 parts of cross-linking agent, 2-2.5 parts of bentonite, 0.5-1 part of fly ash, 2-3 parts of polyvinyl alcohol, 0.5-0.6 part of inhibitor and 100-110 parts of water. The composite material has excellent water retention performance, good resistance effect and stable performance.

Description

Coal mine goaf fire prevention and extinguishment composite material and preparation method thereof

Technical Field

The invention relates to the technical field of new environment-friendly materials, in particular to a coal mine goaf fire prevention and extinguishment composite material and a preparation method thereof.

Background

The coal industry plays a role in the position of the energy structure in China, so that the coal mining strength is also great, and the mine safety protection is particularly important. The fire hazard in mine safety accidents is huge, and the fire is easy to induce gas and coal dust explosion accidents, so that huge economic loss is brought, the life safety of people is seriously threatened, and therefore, the fire prevention and control of the coal mine are of great importance. The ignition of coal is the main cause of coal fire, the goaf of the place mainly occurs, when the heat released by oxidation of coal is larger than the heat lost, the temperature is raised, when the temperature is raised to the critical point of coal spontaneous combustion, and the condition of coal spontaneous combustion possibly occurs due to continuous oxygen supply condition around the coal bed, therefore, the mechanism of coal spontaneous combustion prevention and fire extinguishment of the goaf is generally to isolate oxygen, cool down or weaken the activity of active groups in the coal body. The most common grouting technology is that slurry, fly ash and water are mixed and poured on the surface of a coal bed in a goaf, the coal is wrapped to isolate air, and in addition, the temperature is reduced by water evaporation. The gel technology also plays roles in preventing and extinguishing fire by covering, isolating oxygen, reducing temperature, stopping and the like.

Because the oxidation rate of coal is very slow, the fire prevention and extinguishment of coal seam is also a very lengthy process, and in the process of fire prevention and extinguishment, the fire prevention and extinguishment possibly faces the problems of water loss and cracking of the protective layer and the failure energy of the inhibitor, thereby greatly weakening the fire prevention and extinguishment effect, therefore, the high strength, good water retention and stable performance of the protective layer for the fire prevention and extinguishment of the coal seam are required, and the effect of stable fire prevention and extinguishment of a coal mine goaf can be achieved.

Disclosure of Invention

In view of the above, the invention aims to provide the coal mine goaf fire prevention and extinguishment composite material which has the advantages of excellent water retention performance, good inhibition effect, good permeability to coal seams and stable performance.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 2-3 parts of sodium alginate, 1.2-1.6 parts of cross-linking agent, 2-2.5 parts of bentonite, 0.5-1 part of fly ash, 2-3 parts of polyvinyl alcohol, 0.5-0.6 part of inhibitor and 100-110 parts of water.

Further, the inhibitor is prepared from ammonium polyphosphate, zinc borate and hydrotalcite in a weight ratio of 1:1:2, mixing.

Further, the inhibitor is a microcapsule inhibitor, and is prepared by the following steps:

(1) Ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, mixing uniformly, adding water for granulating, and drying at low temperature;

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder according to the weight ratio of 1:1:2: mixing 0.3-0.5, adding water with the same weight, and heating to 70-80 ℃ until the mixture is in liquid state without obvious particles;

(3) Uniformly spraying the mixed solution in the step (2) on the particles in the step (1) after atomizing, wherein the weight ratio of the mixed solution in the step (2) to the particles in the step (1) in the spraying process is 0.6-0.8:1, then air-drying at low temperature to obtain the microcapsule inhibitor.

Further, the crosslinking agent is an organometallic crosslinking agent.

Further, the organic metal cross-linking agent is an organic boron zirconium cross-linking agent, and is specifically prepared by the following steps:

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH to 2-3, mixing for 30min, slowly dripping triethanolamine and tartaric acid, stirring for 3h, adding borax, and continuously stirring for 3h to obtain a product; the mass ratio of the glycerol to the water is 1.5:1, the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.5-2:10.

a preparation method of a coal mine goaf fire prevention and extinguishing composite material comprises the following steps:

(1) Sodium alginate, bentonite, fly ash, polyvinyl alcohol and inhibitor are stirred uniformly, and water is added for mixing;

(2) Adding boric acid to adjust the pH value to 3.0, then adding a cross-linking agent, and uniformly stirring to obtain the fire prevention and extinguishing composite material.

The beneficial effects of the invention are as follows:

1. the coal mine goaf fire prevention and extinguishing material is a double-network gel system, and the two network structures are mutually crosslinked, so that the ductility and the strength of the gel can be greatly improved; bentonite, fly ash and a stopping agent are also added into the raw materials, so that the finally prepared composite material has remarkable stopping performance, excellent high-temperature water retention and good permeability.

2. Specifically, a polyvinyl alcohol-boric acid covalent crosslinking system and a coordination crosslinking double-crosslinking system formed by a sodium alginate-metal crosslinking agent are adopted. The molecular chain of the polyvinyl alcohol has hydroxyl with stronger polarity, and then a three-dimensional network structure is formed through self-crosslinking, so that the toughness and ductility of the sodium alginate gel system can be greatly improved, namely the strength and toughness of the double-network gel system can be obviously increased, thereby greatly improving the water retention performance and further influencing the fire prevention and extinguishment performance.

Bentonite and fly ash are also added into the system, and the bentonite has strong swelling, adsorptivity and hydrophilicity, and can be mixed and dispersed in a high-molecular double-crosslinked system, so that water molecules and gel molecules can be swelled and adsorbed, the molecular arrangement is tighter, and the strength of the gel layer is increased; in addition, a large amount of bentonite can enlarge the network structure of the gel system, so that the movement rate of water molecules is reduced, and the water retention performance is improved. In order to further reduce the cost, the bentonite is also mixed with the fly ash, so that the bentonite has good filling and wrapping effects, can fill gaps between crushed coals, and can further increase the gel strength.

3. The system is also added with a stopping agent, the stopping agent is a composite stopping agent, the main components of the stopping agent are ammonium polyphosphate, hydrotalcite and zinc borate, wherein aluminum hydroxide in the hydrotalcite is decomposed at about 200 ℃, vaporization absorbs heat and cools, and the residue covers oxygen isolation; the ammonium polyphosphate absorbs heat in the flame-retardant process to decompose N ₂ 、NH ₃ The non-combustible gas is used for diluting oxygen in the air, so that the oxygen flame retardance is blocked; the zinc borate releases crystal water in the flame-retardant process, and the generated product can not only isolate oxygen, but also adsorb combustible gas generated in the combustion process; therefore, the stopping agents are used in a compound way, and can be matched with each other and have complementary advantages.

In order to prevent the performance of the inhibitor in the fire prevention and extinguishing composite material from being influenced, the inhibitor is prepared into a microcapsule inhibitor, namely, the surface of the inhibitor is coated, the coating material is a mixture of polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder, wherein the polyethylene glycol, the pentaerythritol stearate and the paraffin are sprayed on the surface of particles of the inhibitor after being melted, and solidified at a low temperature to form a film, and the flame retardant is slowly heated and decomposed at about 70 ℃ in the flame retardant process, and simultaneously releases the flame retardant, so that on one hand, the failure of the inhibitor can be prevented, and on the other hand, the flame retardant time of the flame retardant can be prolonged, and the flame retardant efficiency is increased. In addition, the glass fiber powder with the length of 20-30 mu m is added, so that the toughness and mechanical strength of the coating layer can be increased to a certain extent.

4. Because the fire prevention and extinguishing material of this application preparation needs to transport to the goaf through the pipeline, consequently need control the time of gel cross-linking to prevent that the too fast pipeline of jam of cross-linking rate, and the too slow covering and infiltration that can lead to the coal seam are incomplete, consequently the cross-linking agent that adopts in this application is organoboron zirconium cross-linking agent, can release the metal ion under certain condition and carry out the cross-linking reaction, can delay the speed of cross-linking reaction. The organic ligands of the organoboron zirconium cross-linking agent are selected from glycerol, triethanolamine and tartaric acid, so that the organoboron zirconium cross-linking agent has rich active groups, the stability of the cross-linking agent can be greatly improved by introducing the organoboron zirconium cross-linking agent, and in addition, the solubility of the coordination reaction can be improved by the glycerol.

Drawings

Fig. 1 is a temperature programmed CO variation curve.

Detailed Description

The invention is further described below in connection with specific embodiments.

Example 1

A coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 2 parts of sodium alginate, 1.2 parts of cross-linking agent, 2 parts of bentonite, 0.5 part of fly ash, 3 parts of polyvinyl alcohol, 0.5 part of inhibitor and 100 parts of water.

The inhibitor is prepared from ammonium polyphosphate, zinc borate and hydrotalcite in a weight ratio of 1:1:2, mixing.

The inhibitor is a microcapsule inhibitor prepared from ammonium polyphosphate, zinc borate and hydrotalcite, and is prepared by the following steps:

(1) Ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, uniformly mixing, adding water for granulating, and drying at low temperature, wherein the particle size of the granules is mainly distributed between 100 mu m and 150 mu m;

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder according to the weight ratio of 1:1:2:0.3, adding water with the same weight, and heating to 70-80 ℃ until the mixture is in a liquid state without obvious particles;

(3) Uniformly spraying the mixed solution in the step (2) on the particles in the step (1) after atomizing, wherein the weight ratio of the mixed solution in the step (2) to the particles in the step (1) in the spraying process is 0.6:1, then air-drying at low temperature to obtain the microcapsule inhibitor.

Wherein the crosslinking agent is an organic metal crosslinking agent, and is specifically prepared by the following steps:

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH to 2-3, mixing for 30min, slowly dripping triethanolamine and tartaric acid, stirring for 3h, adding borax, and continuously stirring for 3h to obtain a product; the mass ratio of the glycerol to the water is 1.5:1, the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.5:10.

Example 2

A coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 2.2 parts of sodium alginate, 1.3 parts of cross-linking agent, 2.1 parts of bentonite, 0.6 part of fly ash, 2 parts of polyvinyl alcohol, 0.52 part of inhibitor and 105 parts of water.

The inhibitor is a microcapsule inhibitor of ammonium polyphosphate, zinc borate and hydrotalcite, and is prepared by the following steps:

(1) Ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, uniformly mixing, adding water and granulating;

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder according to the weight ratio of 1:1:2:0.4, adding water with the same weight, and heating to 70-80 ℃ until the mixture is in a liquid state without obvious particles;

(3) Spraying the mixed solution obtained in the step (2) on the particles obtained in the step (1) uniformly after atomizing, wherein the spraying ratio is 0.7:1, then air-drying at low temperature to obtain the microcapsule inhibitor.

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH to 2-3, mixing for 30min, slowly dripping triethanolamine and tartaric acid, stirring for 3h, adding borax, and continuously stirring for 3h to obtain a product; the mass ratio of the glycerol to the water is 1.5:1, the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.6:10.

example 3

A coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 2.8 parts of sodium alginate, 1.4 parts of cross-linking agent, 2.2 parts of bentonite, 0.8 part of fly ash, 2.2 parts of polyvinyl alcohol, 0.55 part of inhibitor and 105 parts of water.

example 4

A coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 3 parts of sodium alginate, 1.6 parts of cross-linking agent, 2.4 parts of bentonite, 1 part of fly ash, 2.8 parts of polyvinyl alcohol, 0.58 part of inhibitor and 110 parts of water.

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder according to the weight ratio of 1:1:2: mixing 0.35, adding water with the same weight, and heating to 70-80 ℃ until the mixture is in a liquid state without obvious particles;

(3) Spraying the mixed solution obtained in the step (2) on the particles obtained in the step (1) uniformly after atomizing, wherein the spraying ratio is 0.8:1, then air-drying at low temperature to obtain the microcapsule inhibitor.

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH to 2-3, mixing for 30min, slowly dripping triethanolamine and tartaric acid, stirring for 3h, adding borax, and continuously stirring for 3h to obtain a product; the mass ratio of the glycerol to the water is 1.5:1, the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.8:10.

example 5

A coal mine goaf fire prevention and extinguishing composite material is prepared from the following raw materials in parts by weight: 2.5 parts of sodium alginate, 1.5 parts of cross-linking agent, 2.5 parts of bentonite, 0.6 part of fly ash, 2.5 parts of polyvinyl alcohol, 0.6 part of inhibitor and 105 parts of water.

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder according to the weight ratio of 1:1:2: mixing 0.45, adding water with the same weight, and heating to 70-80 ℃ until the mixture is in a liquid state without obvious particles;

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH to 2-3, mixing for 30min, slowly dripping triethanolamine and tartaric acid, stirring for 3h, adding borax, and continuously stirring for 3h to obtain a product; the mass ratio of the glycerol to the water is 1.5:1, the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:2:10.

comparative example 1

Comparative example 1 was substantially the same as example 5 except that no polyvinyl alcohol was added to the raw material.

Comparative example 2

Comparative example 1 was substantially the same as example 5 except that no inhibitor was added to the raw material.

Performance detection

The gel time, inhibition property, thermal stability and penetration property of the fire-extinguishing materials prepared in examples 1 to 5 and comparative examples 1 to 2 were examined.

Wherein the stopping performance is referred to as follows: selecting a coal sample, crushing and screening, selecting an experimental coal sample with the particle size of 40-60 meshes, drying, and preserving for use. One part is a coal sample of 50g, and the other four parts are respectively added with 5g of the gel prepared in the example 4, the example 5, the comparative example 1 and the comparative example 2, and the gel is used after being uniformly mixed; the coal sample tank is supplied with 100 mL/min dry air, the heating range is 50-180 ℃, the heating rate is 1 ℃/min, and the condition of index gas (CO) released in the oxidation heating process in the coal sample tank is tested.

The thermal stability performance detection method comprises the following steps: 100g of gel and homogeneous water are respectively placed in a constant temperature drying oven to be heated at a constant speed, the heating range is 100-200 ℃, and the weight loss rate is respectively detected.

Permeability properties: uniformly spreading crushed coal bodies with the particle size of 1-2cm on a metal net of a cylindrical container, uniformly pouring water, the composite material gel prepared in examples 1-5 and comparative examples 1-2 on the crushed coal respectively, weighing the mass of the water and the gel permeated in the container below after 30min, and calculating the ratio of the permeation mass to the initial mass as a reference permeability.

The test results are described below:

1. taking 5mL of the product prepared in examples 1-5 of the application, pouring into a funnel every 5min, observing and recording the time for the mixed solution to flow through the funnel; when the length of the gel flowing through the funnel exceeds 50% of the last time and the surface of the mixed solution is free of free water, the gel forming can be judged, the gel time of the gel forming product is 10-12min, and the gel forming product is suitable for pipeline transportation.

2. As can be seen from fig. 1, the results of the resistance performance tests of examples 4 and 5 and comparative examples 1 and 2 are shown in fig. 1, and the CO yield is small at the early stage of temperature rise and the speed is slow; as the temperature increases, the CO amount increases exponentially, but it is evident from the curves of example 4 and example 5 that the CO yield of the gel-treated product prepared by the present application is significantly slowed, which indicates that the gel of the present application can significantly inhibit oxidation of coal, and the CO release of the gel-treated coal sample of example 5 is reduced by 72.4% at 100 ℃.

As can be seen from the combination of comparative examples 1 and 2, comparative examples 1 and 2 also have remarkable stopping properties, but the effect is weaker than that of example 5, and the stopping properties of comparative example 1 are better than those of comparative example 2, which means that the addition of stopping agent has a strong enhancing effect on the fire preventing and extinguishing properties of the present application.

TABLE 1 thermal stability test

3. As can be seen from the thermal stability of Table 1, the fire-fighting gel prepared by the application has excellent water retention performance, and still has strong water retention at a high temperature of 200 ℃, and the double gel system is helpful for increasing the water retention effect as can be seen by referring to the result of comparative example 1.

4. The permeability of the detected water is 93.51%, the permeability of examples 1-5 are 23.91%, 23.42%, 24.18%, 22.15% and 25.92% respectively, and the permeability of comparative examples 1-2 are 29.54% and 26.65% respectively, which means that the composite materials prepared in examples 1-5 of the application can permeate to the surface of a coal seam, thereby playing roles of blocking the gap of the coal body and reducing the oxygen around the coal body.

Finally, it is noted that the above-mentioned embodiments are merely for illustrating the technical solution of the present invention, and that other modifications and equivalents thereof by those skilled in the art should be included in the scope of the claims of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A coal mine goaf fire prevention composite material is characterized in that: the traditional Chinese medicine is prepared from the following raw materials in parts by weight: 2-3 parts of sodium alginate, 1.2-1.6 parts of cross-linking agent, 2-2.5 parts of bentonite, 0.5-1 part of fly ash, 2-3 parts of polyvinyl alcohol, 0.5-0.6 part of inhibitor and 100-110 parts of water;

the inhibitor is microcapsule inhibitor and is prepared by the following steps:

(3) Spraying the mixed solution obtained in the step (2) on the particles obtained in the step (1) uniformly after atomizing, wherein the spraying ratio is 0.6-0.8:1, then air-drying at low temperature to obtain a microcapsule inhibitor;

the polyvinyl alcohol is a covalent crosslinking system of polyvinyl alcohol-boric acid.

2. The coal mine goaf fire prevention and extinguishing composite material according to claim 1, wherein: the crosslinker is an organometallic crosslinker.

3. The coal mine goaf fire prevention and extinguishing composite material according to claim 2, wherein: the organic metal cross-linking agent is an organic boron zirconium cross-linking agent, and is specifically prepared by the following steps:

4. a method for preparing the coal mine goaf fire prevention and extinguishing composite material, which is characterized in that: the method comprises the following steps: