CN115245646A - A kind of coal mine goaf fire prevention and fire-extinguishing composite material and preparation method thereof - Google Patents

Abstract

The invention discloses a coal mine goaf fire prevention and fire-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 a crosslinking agent, 2-2.5 parts of bentonite, and 0.5 parts of fly ash -1 part, 2-3 parts of polyvinyl alcohol, 0.5-0.6 part of chemical inhibitor, 100-110 parts of water. The composite material has excellent water retention performance, good resistance effect and stable performance.

Description

A kind of coal mine goaf anti-fire composite material and preparation method thereof

technical field

The invention relates to the technical field of new environmental protection materials, in particular to a fire-fighting composite material for gobs in coal mines and a preparation method thereof.

Background technique

The coal industry plays an important role in my country's energy structure, so our coal mining efforts are also very strong, and mine safety protection is particularly important. Fire hazards in mine safety accidents are huge, and fires can easily induce gas and coal dust explosion accidents, which will bring huge economic losses and seriously threaten people's lives. Therefore, fire prevention in coal mines is very important. Coal mine fires are mainly caused by spontaneous combustion of coal, and the main place of occurrence is in the goaf. When the heat released by coal oxidation is greater than the heat lost, the temperature starts to rise. When the temperature rises to the critical point of coal spontaneous combustion, and there is a continuous oxygen supply around the coal seam Therefore, the mechanism for preventing and extinguishing coal spontaneous combustion in gobs is generally to isolate oxygen, cool down, or weaken the activity of active groups in the coal body. The most commonly used grouting technology is generally to mix mud and fly ash with water and pour it onto the surface of the coal seam in the goaf, to isolate the air by wrapping the coal, and to cool down through the evaporation of water. The gel technology also plays a role in preventing and extinguishing fires by covering, isolating oxygen, cooling, and resisting chemicals.

Due to the slow oxidation rate of coal, fire prevention and extinguishment of coal seams is also a very long process. In the process of fire prevention and extinguishment, the fire prevention and extinguishment may face the problems of dehydration, cracking of the protective layer, and failure of inhibitors, which greatly weakens the fire prevention and extinguishment. Therefore, it is required that the coal seam fire protection layer has high strength, good water retention and stable performance, so as to achieve the stable fire prevention effect of the coal mine goaf.

SUMMARY OF THE INVENTION

In view of this, the object of the present invention is to address the deficiencies of the prior art and provide a fire-fighting composite material for gobs in coal mines, which has excellent water retention performance, good chemical resistance, good permeability to coal seams, and stable performance.

To achieve the above object, the present invention adopts the following technical solutions:

A fire-fighting composite material for gobs in coal mines, which is made of the following raw materials in parts by weight: 2-3 parts of sodium alginate, 1.2-1.6 parts of crosslinking agent, 2-2.5 parts of bentonite, and 0.5-1 part of fly ash , 2-3 parts of polyvinyl alcohol, 0.5-0.6 parts of inhibitor, 100-110 parts of water.

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

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

(1) Mix ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, add water to granulate, and dry at low temperature;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder in a weight ratio of 1:1:2:0.3-0.5, add water of the same weight, and heat at 70-80°C until it becomes liquid, without Obvious particles;

(3) Atomize the mixed liquid in step (2) and evenly spray it on the particles in step (1), wherein the weight ratio of the mixed liquid in step (2) to the particles in step (1) is 0.6-0.8 during the spraying process : 1, then air-dried at low temperature to obtain microcapsule inhibitor.

Further, the crosslinking agent is an organometallic crosslinking agent.

Further, the organometallic crosslinking agent is an organoboron zirconium crosslinking agent, specifically prepared by the following steps:

Mix zirconium oxychloride, glycerol and water, heat in a water bath to 60-70°C, adjust the pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours, The product obtained; the mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.5-2:10.

A method for preparing a fire-fighting composite material in a coal mine goaf, comprising the following steps:

(1) Sodium alginate, bentonite, fly ash, polyvinyl alcohol and inhibitor are stirred evenly, and mixed with water;

(2) Add boric acid to adjust the pH to 3.0, then add a crosslinking agent and stir evenly to obtain a fire-resistant composite material.

The beneficial effects of the present invention are:

1. The anti-fire extinguishing material for coal mine goaf in this application is a double-network gel system, and the two network structures are cross-linked with each other, which can greatly improve the ductility and strength of the gel; bentonite and pulverized coal are also added to the raw materials Ash and chemical inhibitor, the final prepared composite material has remarkable chemical resistance, excellent high temperature water retention and good permeability.

2. Specifically, a covalent cross-linking system formed by polyvinyl alcohol-boric acid covalent cross-linking system and sodium alginate-metal cross-linking agent is used. Among them, there are strong polar hydroxyl groups in the molecular chain of polyvinyl alcohol, and then form a three-dimensional network structure through self-crosslinking, which can greatly improve the toughness and ductility of the sodium alginate gel system, that is, the strength and ductility of the double network gel system. The toughness will increase significantly, which can greatly improve the water retention performance, and then affect its fire resistance performance.

Bentonite and fly ash are also added to the system. Bentonite has strong swelling, adsorption, and hydrophilic properties. Mixing and dispersing it in the double-crosslinked polymer system can swell and absorb water molecules and gel molecules. Make the molecular arrangement more compact and increase the strength of the gel layer; in addition, a large amount of bentonite can expand the network structure of the gel system, thereby reducing the movement rate of water molecules and increasing the water retention performance. In order to further reduce the cost, the bentonite is also mixed with fly ash, which has a good filling and wrapping effect, can fill the gaps between crushed coal, and can further increase the gel strength.

3. Inhibitors are also added to the system. The inhibitors are composite inhibitors whose main components are ammonium polyphosphate, hydrotalcite and zinc borate. Aluminum hydroxide in hydrotalcite decomposes at about 200°C, vaporized and absorbed Thermal cooling, the residue is covered with oxygen insulation; ammonium polyphosphate absorbs heat during the flame retardant process, decomposes non-combustible gases such as N ₂ and NH ₃ , which dilutes the oxygen in the air, thereby blocking the oxygen flame retardant; zinc borate Crystal water is released during the flame retardant process, and the resulting product can not only block oxygen, but also absorb the flammable gas produced during the combustion process; therefore, these several inhibitors are used in combination, which can cooperate with each other and complement each other.

In order to prevent the performance of the inhibitor in the fire-resistant composite material from being affected, this application prepares the inhibitor into a microcapsule inhibitor, that is, coats the surface of the inhibitor, and the coating material is polyethylene glycol, pentaerythritol hard A mixture of fatty acid esters, paraffin wax and glass fiber powder, in which polyethylene glycol, pentaerythritol stearate and paraffin wax are melted and sprayed on the surface of the inhibitor particles, solidified at low temperature to form a film, in the process of flame retardancy, at 70 ° C The left and right will be slowly decomposed by heat, and release the flame retardant while it is flame retardant. On the one hand, it can prevent the failure of the chemical retardant, and on the other hand, it can prolong the flame retardant time of the flame retardant, thereby increasing the flame retardant efficiency. In addition, this application also adds glass fiber powder with a length of 20-30 μm, which can increase the toughness and mechanical strength of the cladding layer to a certain extent.

4. Since the anti-fire extinguishing material prepared by this application needs to be transported to the goaf through pipelines, it is necessary to control the time of gel crosslinking to prevent the crosslinking rate from being too fast to block the pipeline, while the speed is too slow to cause damage to the coal seam. The coverage and penetration are not complete, so the crosslinking agent used in this application is an organoboron zirconium crosslinking agent, which can release metal ions to carry out crosslinking reaction under certain conditions, and can delay the speed of crosslinking reaction. The organic ligands of organoboron-zirconium crosslinking agents are glycerol, triethanolamine and tartaric acid, which have abundant active groups, and the introduction can greatly improve the stability of crosslinking agents. Solubility.

Description of drawings

Figure 1 is the curve of CO change with temperature programming.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

A fire-fighting composite material for gobs in coal mines, made of the following raw materials in parts by weight: 2 parts of sodium alginate, 1.2 parts of crosslinking agent, 2 parts of bentonite, 0.5 parts of fly ash, 3 parts of polyvinyl alcohol, retardant 0.5 parts of chemical agent, 100 parts of water.

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

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

(1) Ammonium polyphosphate, zinc borate, hydrotalcite and starch are mixed evenly at a weight ratio of 1:1:2:2, granulated with water, dried at low temperature, and the particle size is mainly distributed between 100 μm and 150 μm;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder at a weight ratio of 1:1:2:0.3, add the same weight of water, heat at 70-80°C until it becomes liquid, and there are no obvious particles ;

(3) Atomize the mixed solution in step (2) and evenly spray it on the particles in step (1), wherein the weight ratio of the mixed solution in step (2) to the particles in step (1) during the spraying process is 0.6:1 , and then air-dried at low temperature to obtain a microcapsule inhibitor.

Wherein the crosslinking agent organometallic crosslinking agent is specifically prepared by the following steps:

Mix zirconium oxychloride, glycerin and water, heat in a water bath to 60-70°C, adjust pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours to obtain the product ; The mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.5:10.

A method for preparing a fire-fighting composite material in a coal mine goaf, comprising the following steps:

(1) Sodium alginate, bentonite, fly ash, polyvinyl alcohol and inhibitor are stirred evenly, and mixed with water;

(2) Add boric acid to adjust the pH to 3.0, then add a crosslinking agent and stir evenly to obtain a fire-resistant composite material.

Example 2

A fire-fighting composite material for coal mine goaf, made of the following raw materials in parts by weight: 2.2 parts of sodium alginate, 1.3 parts of crosslinking agent, 2.1 parts of bentonite, 0.6 parts of fly ash, 2 parts of polyvinyl alcohol, retardant Chemical agent 0.52 parts, water 105 parts.

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

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

(1) Mix ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, add water to granulate;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder in a weight ratio of 1:1:2:0.4, add the same weight of water, heat at 70-80°C until it becomes liquid, and there are no obvious particles ;

(3) Atomize the mixture in step (2) and evenly spray it on the particles in step (1) at a spraying ratio of 0.7:1, then air-dry at low temperature to obtain a microcapsule inhibitor.

Wherein the crosslinking agent organometallic crosslinking agent is specifically prepared by the following steps:

Mix zirconium oxychloride, glycerin and water, heat in a water bath to 60-70°C, adjust pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours to obtain the product The mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.6:10.

Example 3

A fire-fighting composite material for coal mine goaf, made of the following raw materials in parts by weight: 2.8 parts of sodium alginate, 1.4 parts of crosslinking agent, 2.2 parts of bentonite, 0.8 parts of fly ash, 2.2 parts of polyvinyl alcohol, retardant 0.55 parts of chemical agent, 105 parts of water.

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

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

(1) Mix ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, add water to granulate;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder in a weight ratio of 1:1:2:0.4, add the same weight of water, heat at 70-80°C until it becomes liquid, and there are no obvious particles ;

(3) Atomize the mixture in step (2) and evenly spray it on the particles in step (1) at a spraying ratio of 0.7:1, then air-dry at low temperature to obtain a microcapsule inhibitor.

Wherein the crosslinking agent organometallic crosslinking agent is specifically prepared by the following steps:

Mix zirconium oxychloride, glycerin and water, heat in a water bath to 60-70°C, adjust pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours to obtain the product The mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.6:10.

Example 4

A fire-fighting composite material for coal mine goaf, made of the following raw materials in parts by weight: 3 parts of sodium alginate, 1.6 parts of crosslinking agent, 2.4 parts of bentonite, 1 part of fly ash, 2.8 parts of polyvinyl alcohol, retardant 0.58 parts of chemical agent, 110 parts of water.

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

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

(1) Mix ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, add water to granulate;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder at a weight ratio of 1:1:2:0.35, add the same weight of water, heat at 70-80°C until it becomes liquid, and there are no obvious particles ;

(3) Atomize the mixture in step (2) and evenly spray it on the granules in step (1) at a spraying ratio of 0.8:1, then air-dry at low temperature to obtain a microcapsule inhibitor.

Wherein the crosslinking agent organometallic crosslinking agent is specifically prepared by the following steps:

Mix zirconium oxychloride, glycerin and water, heat in a water bath to 60-70°C, adjust pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours to obtain the product The mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:1.8:10.

Example 5

A fire-fighting composite material for coal mine goaf, made of the following raw materials in parts by weight: 2.5 parts of sodium alginate, 1.5 parts of crosslinking agent, 2.5 parts of bentonite, 0.6 parts of fly ash, 2.5 parts of polyvinyl alcohol, 0.6 parts of chemical agent, 105 parts of water.

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

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

(1) Mix ammonium polyphosphate, zinc borate, hydrotalcite and starch in a weight ratio of 1:1:2:2, add water to granulate;

(2) After mixing polyethylene glycol, pentaerythritol stearate, paraffin wax and glass fiber powder at a weight ratio of 1:1:2:0.45, add the same weight of water, heat at 70-80°C until it becomes liquid, and there are no obvious particles ;

(3) Atomize the mixture in step (2) and evenly spray it on the granules in step (1) at a spraying ratio of 0.8:1, then air-dry at low temperature to obtain a microcapsule inhibitor.

Wherein the crosslinking agent organometallic crosslinking agent is specifically prepared by the following steps:

Mix zirconium oxychloride, glycerin and water, heat in a water bath to 60-70°C, adjust pH to 2-3, mix for 30 minutes, then slowly add triethanolamine and tartaric acid dropwise, stir for 3 hours, then add borax and continue stirring for 3 hours to obtain the product ; The mass ratio of glycerol to water is 1.5:1, and the molar ratio of boron, zirconium, triethanolamine, tartaric acid and glycerol is 2:1:2:2:10.

Comparative Example 1

Comparative Example 1 is basically the same as Example 5, except that polyvinyl alcohol is not added in the raw materials.

Comparative Example 2

Comparative Example 1 is basically the same as Example 5, except that no inhibitor is added to the raw materials.

Performance testing

The gelation time, chemical resistance, thermal stability and permeability of the fire prevention and extinguishing materials prepared in Examples 1-5 and Comparative Examples 1-2 were tested.

The chemical resistance performance refers to the following steps: select coal samples, select experimental coal samples with a particle size of 40-60 mesh after crushing and screening, and store them for future use after drying. One part is the coal sample of 50g, and the other four parts add the gel prepared by 5g of embodiment 4, embodiment 5, comparative example 1 and comparative example 2 respectively, and use after mixing; the coal sample tank supplies 100 mL/min of dry Air, the temperature range is 50°C-180°C, the temperature rise rate is 1°C/min, and the indicator gas (CO) released during the oxidation and temperature rise process in the coal sample tank is tested.

Thermal stability test method: 100g of gel and the same mass of water were placed in a constant temperature drying oven to raise the temperature at a constant rate, and the temperature range was 100-200°C, and the weight loss rate was tested respectively.

Permeability: Evenly spread the crushed coal body with a particle size of 1-2cm on the metal mesh of the cylindrical container, pour water, the composite material gel prepared in Example 1-5, and Comparative Example 1-2 evenly on the crushed coal, After 30 min, the mass of water and gel permeated in the container below was weighed, and the ratio of the permeated mass to the initial mass was calculated as the reference permeability.

See the following description for the test results:

1. Take 5 mL of the product prepared in Example 1-5 of the present application, pour it into the funnel every 5 minutes, observe and record the time for the mixed solution to flow through the funnel; If there is no free water, it can be judged that it has been gelled. The gel time of the product of this application is 10-12min, which is suitable for pipeline transportation.

2. Refer to Figure 1 for the results of the resistance test of Examples 4 and 5 and Comparative Example 1 and Comparative Example 2. As can be seen from Figure 1, the CO production in the early stage of heating is small and the growth rate is very slow; as the temperature rises, the amount of CO Exponentially increased, but combined with the curves of Example 4 and Example 5, it can be clearly seen that the production of CO produced by the gel-treated product prepared by the present application slows down significantly, indicating that the gel of the present application can significantly inhibit coal oxidation. , at 100°C, the CO emission of the coal sample treated with the gel in Example 5 decreased by 72.4%, and the inhibition effect was remarkable.

Combining Comparative Example 1 and Comparative Example 2, it can be seen that Comparative Example 1 and Comparative Example 2 also have obvious resistance performance, but their effect is weaker than that of Example 5, and the resistance performance of Comparative Example 1 is better than that of Comparative Example 2. It shows that the addition of the inhibitor has a strong enhancement effect on the fire prevention and extinguishing performance of the present application.

Table 1 Thermal stability performance test

3. From the thermal stability performance in Table 1, it can be seen that the anti-fire extinguishing gel prepared by the present application has excellent water retention performance, and still has strong water retention performance at a high temperature of 200 ° C. Referring to the results of Comparative Example 1, it can be seen that double coagulation The glue system helps to increase the water-fixing effect.

4. The permeability of tested water is 93.51%, the permeability of embodiment 1-5 is respectively 23.91%, 23.42%, 24.18%, 22.15%, 25.92%, the permeability of comparative example 1-2 is respectively 29.54% and 26.65%, indicating 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 the coal body and reducing the oxygen around the coal body.

Finally, it is noted that the above embodiments are only used to illustrate the technical solution of the present invention without limitation, other modifications or equivalent replacements made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and spirit of the technical solution of the present invention All should be included in the scope of the claims of the present invention.

Claims (6)

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:

(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 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;

(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.

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