CN115245646A

CN115245646A - Coal mine goaf fire prevention and extinguishing composite material and preparation method thereof

Info

Publication number: CN115245646A
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: 2022-10-28
Anticipated expiration: 2042-01-04
Also published as: CN115245646B

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 stopping agent and 100-110 parts of water. The composite material has excellent water retention performance, good inhibition effect and stable performance.

Description

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

Technical Field

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

Background

The coal industry plays a significant role in energy structure in China, so that the mining strength of coal mines is high, and the safety protection of mines is particularly important. The fire hazard in the mine safety accident is huge, and the fire disaster also easily induces gas and coal dust explosion accidents, thereby bringing huge economic loss and seriously threatening the life safety of people, so the fire prevention and control of the coal mine are very important. The coal spontaneous combustion is the main reason for coal mine fire, coal spontaneous combustion is mainly caused, the goaf is mainly in a place, when the heat released by coal oxidation is larger than the dissipated heat, the temperature begins to rise, and when the temperature rises to the coal spontaneous combustion critical point and the coal bed is surrounded by continuous oxygen supply conditions, the coal spontaneous combustion condition can occur, so that the spontaneous combustion fire prevention and extinguishing mechanism of the coal in the goaf generally is to isolate oxygen, reduce the temperature or weaken the activity of active groups in the coal. The most commonly used grouting technique generally mixes slurry, fly ash and water and pours the mixture into the coal seam surface of the goaf, and the coal is wrapped to isolate air, and in addition, the temperature is reduced through moisture evaporation. The gel technology also plays a role in fire prevention and extinguishing through covering, oxygen isolation, temperature reduction, inhibition and the like.

Because the coal oxidation rate is very slow, the fire prevention and extinguishing of coal seam is a very long process, in the process of fire prevention and extinguishing, the fire prevention and extinguishing may face the problems of water loss and cracking of the protective layer and failure of stopping agent, so that the effect of fire prevention and extinguishing is greatly weakened, and therefore the coal seam fire prevention and extinguishing protective layer is required to have high strength, good water retention and stable performance, so that the effect of stable fire prevention and extinguishing in the coal mine goaf can be achieved.

Disclosure of Invention

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

In order to achieve the 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 stopping agent and 100-110 parts of water.

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

Further, the stopping agent is a microcapsule stopping agent 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 granulation, and drying at low temperature;

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

(3) Atomizing the mixed liquor in the step (2) and then uniformly spraying the atomized mixed liquor on the particles in the step (1), wherein the weight ratio of the mixed liquor 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 stopping agent.

Further, the crosslinking agent is an organometallic crosslinking agent.

Further, the organic metal crosslinking agent is an organic boron zirconium crosslinking agent, and is 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, then slowly dropwise adding triethanolamine and tartaric acid, stirring for reacting for 3h, then adding borax, and continuing 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 to zirconium to triethanolamine to tartaric acid to 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) Uniformly stirring sodium alginate, bentonite, fly ash, polyvinyl alcohol and a stopping agent, and adding water 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-preventing and extinguishing composite material.

The beneficial effects of the invention are:

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

2. In particular to a coordination crosslinking double-crosslinking system formed by a polyvinyl alcohol-boric acid covalent crosslinking system and a sodium alginate-metal crosslinking agent. 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 the ductility of a sodium alginate gel system can be greatly improved, namely the strength and the toughness of a double-network gel system can be obviously increased, and further the water retention performance can be greatly improved, and the fire prevention and extinguishing performance of the double-network gel system is influenced.

Bentonite and fly ash are added in the system, the bentonite has strong swelling property, adsorbability and hydrophilicity, and the bentonite is mixed and dispersed in a macromolecular double-crosslinking system and can swell and adsorb water molecules and gel molecules, so that the molecular arrangement is more compact, and the strength of a gel layer is increased; in addition, a large amount of bentonite can expand the network structure of a 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 among crushed coal, and can further increase the gel strength.

3. The system is also added with a stopping agent which is a composite stopping agent and mainly comprises ammonium polyphosphate, hydrotalcite and zinc borate, wherein aluminum hydroxide in the hydrotalcite at about 200 ℃ is decomposed, evaporated, absorbed in heat and cooled, and residues are covered with oxygen insulation; absorbing heat and decomposing N in the flame-retardant process of ammonium polyphosphate ₂ 、NH ₃ The like, which plays a role in diluting oxygen in the air so as to block oxygen flame retardance; 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 inhibitor can be used in a composite way, and can be matched with each other and have complementary advantages.

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

4. The fire prevention and extinguishing material prepared by the method needs to be transported to a goaf through a pipeline, so that the gel crosslinking time needs to be controlled to prevent the pipeline from being blocked due to too high crosslinking rate and incomplete coverage and permeation of a coal bed due to too low speed, and therefore, the crosslinking agent adopted by the method is an organic boron zirconium crosslinking agent, can release metal ions to perform crosslinking reaction under certain conditions, and can delay the crosslinking reaction speed. The organic ligand of the organic boron-zirconium cross-linking agent is selected from glycerol, triethanolamine and tartaric acid, so that the organic boron-zirconium cross-linking agent has abundant active groups, the stability of the cross-linking agent can be greatly improved by introducing the organic ligand, and the solubility of the coordination reaction can be improved by glycerol.

Drawings

Fig. 1 is a temperature programmed CO curve.

Detailed Description

The invention is further described with reference to specific examples.

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 stopping agent 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 components.

The stopping agent is a microcapsule stopping agent 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 granulation, and drying at low temperature, wherein the particle size of the particles is mainly distributed between 100 and 150 mu m;

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

(3) Atomizing the mixed liquor in the step (2), and uniformly spraying the atomized mixed liquor on the particles in the step (1), wherein the weight ratio of the mixed liquor 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 stopping agent.

The crosslinking agent organic metal crosslinking agent is prepared by the following steps:

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH value to 2-3, mixing for 30min, then slowly dripping triethanolamine and tartaric acid, stirring for reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to 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 stopping agent and 105 parts of water.

The stopping agent is a microcapsule stopping agent 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, and adding water for granulation;

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

(3) Atomizing the mixed solution in the step (2), and then uniformly spraying the atomized mixed solution on the particles in the step (1), wherein the spraying ratio is 0.7:1, then air-drying at low temperature to obtain the microcapsule stopping agent.

The crosslinking agent is an organic metal crosslinking agent, and is 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, then slowly dropwise adding triethanolamine and tartaric acid, stirring for reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to 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 stopping agent and 105 parts of water.

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

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH value to 2-3, mixing for 30min, then slowly dripping triethanolamine and tartaric acid, stirring for reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to glycerol is 2:1:2:1.6:10.

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 stopping agent and 110 parts of water.

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

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

(3) Atomizing the mixed solution in the step (2), and then uniformly spraying the atomized mixed solution on the particles in the step (1), wherein the spraying proportion is 0.8:1, then air-drying at low temperature to obtain the microcapsule stopping agent.

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in a water bath, adjusting the pH value to 2-3, mixing for 30min, then slowly dripping triethanolamine and tartaric acid, stirring for reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to 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 stopping agent and 105 parts of water.

(2) Polyethylene glycol, pentaerythritol stearate, paraffin and glass fiber powder in a weight ratio of 1:1:2:0.45, adding water with the same weight, and heating to the temperature of 70-80 ℃ until the mixture is liquid 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, then slowly dropwise adding triethanolamine and tartaric acid, stirring for reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to glycerol is 2:1:2:2:10.

comparative example 1

Comparative example 1 is substantially the same as example 5 except that polyvinyl alcohol was not added to the starting material.

Comparative example 2

Comparative example 1 is essentially the same as example 5 except that no inhibitor is added to the feed.

Performance detection

The fire-fighting materials prepared in examples 1 to 5 and comparative examples 1 to 2 were examined for gelling time, inhibition property, thermal stability and permeability.

Wherein the inhibition performance is referred to the following steps: selecting a coal sample, crushing and screening, selecting an experimental coal sample with the particle size of 40-60 meshes, drying and storing for later use. One part was 50g of the coal sample, and the other four parts were added with 5g of the gels prepared in example 4, example 5, comparative example 1 and comparative example 2, respectively, and used after mixing them uniformly; the coal sample tank is supplied with 100 mL/min of dry air, the temperature rise range is 50-180 ℃, the temperature rise rate is 1 ℃/min, and the condition of the index gas (CO) released in the oxidation temperature rise process in the coal sample tank is tested.

The thermal stability performance detection method comprises the following steps: 100g of gel and the same mass of 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 performance: crushed coal bodies with the particle size of 1-2cm are uniformly paved on a metal mesh of a cylindrical container, water, the composite material gel prepared in the examples 1-5 and the comparative examples 1-2 are uniformly poured on the crushed coal, the mass of the water and the gel penetrating into the lower container is weighed after 30min, and the ratio of the penetrating mass to the initial mass is calculated to be taken as the reference permeability.

The test results are described below:

1.5 mL of the product prepared in examples 1-5 of this application were poured into the funnel every 5min, and the time for the mixed solution to flow through the funnel was observed and recorded; when the time for flowing through the funnel is more than 50% of the last time, and the surface of the mixed solution has no free water, the mixed solution can be judged to be gelatinized, and the gel time of the product is 10-12min, so that the product is suitable for pipeline transportation.

2. Referring to fig. 1, the results of the inhibition performance tests of examples 4 and 5 and comparative examples 1 and 2 show that the yield of CO is low at the early stage of temperature increase and the rate of increase is slow as shown in fig. 1; the CO content is exponentially increased along with the temperature rise, but the curves of the example 4 and the example 5 are combined to obviously show that the CO yield of the gel-treated product prepared by the method is obviously reduced, so that the gel can obviously inhibit the coal oxidation, the CO release amount of the coal sample subjected to the gel treatment of the example 5 is reduced by 72.4% at 100 ℃, and the inhibition effect is obvious.

As can be seen by combining comparative example 1 and comparative example 2, comparative example 1 and comparative example 2 also have obvious inhibition performance, but the effect is weaker than that of example 5, and the inhibition performance of comparative example 1 is better than that of comparative example 2, which shows that the addition of the inhibitor has strong enhancement effect on the fire prevention and extinguishing performance of the application.

TABLE 1 Heat stability Performance test

3. As can be seen from the thermal stability performance of the table 1, the fire prevention and extinguishing gel prepared by the method has excellent water retention performance, and still has strong water retention at a high temperature of 200 ℃, and the result of the comparative example 1 shows that the double-gel system is beneficial to increasing the water fixing effect.

4. The detected permeability of water is 93.51%, the permeability of examples 1-5 is 23.91%, 23.42%, 24.18%, 22.15%, and 25.92%, and the permeability of comparative examples 1-2 is 29.54% and 26.65%, respectively, which shows that the composite material prepared in examples 1-5 of the present application can penetrate to the surface of the coal seam, thereby blocking the gap between coal bodies and reducing oxygen around the coal bodies.

Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and other modifications or equivalent substitutions made by the technical solutions of the present invention by those of ordinary skill in the art should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. The utility model provides a coal mine goaf fire prevention combined material which characterized in that: the feed 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 stopping agent and 100-110 parts of water.

2. The coal mine goaf fire prevention and extinguishing composite material as claimed in claim 1, wherein: the inhibitor is prepared from ammonium polyphosphate, zinc borate and hydrotalcite in a weight ratio of 1:1:2, mixing the components.

3. The coal mine goaf fire prevention and extinguishing composite material according to claim 1 or 2, characterized in that: the stopping agent is a microcapsule stopping agent and is prepared by the following steps:

(3) Atomizing the mixed solution in the step (2), and then uniformly spraying the atomized mixed solution on the particles in the step (1), wherein the spraying proportion is 0.6-0.8:1, then air-drying at low temperature to obtain the microcapsule stopping agent.

4. The coal mine goaf fire prevention and extinguishing composite material as claimed in claim 1, wherein: the crosslinking agent is an organometallic crosslinking agent.

5. The coal mine goaf fire prevention and extinguishing composite material as claimed in claim 4, wherein: the organic metal crosslinking agent is an organic boron zirconium crosslinking agent and is prepared by the following steps:

mixing zirconium oxychloride, glycerol and water, heating to 60-70 ℃ in water bath, adjusting the pH value to 2-3, mixing for 30min, then slowly dripping triethanolamine and tartaric acid, stirring and reacting for 3h, then 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 to zirconium to triethanolamine to tartaric acid to glycerol is 2:1:2:1.5-2:10.

6. a preparation method of the coal mine goaf fire prevention and extinguishing composite material as claimed in claim 1, which is characterized in that: the method comprises the following steps:

(1) Stirring sodium alginate, bentonite, fly ash, polyvinyl alcohol and stopping agent uniformly, and adding water for mixing;