A composite explosion inhibitor for suppressing coal dust explosion and its preparation method

Abstract

The present invention discloses a composite explosion inhibitor for suppressing coal dust explosion and a preparation method thereof, which are made of the following raw materials by weight fraction: 15.6 - 40 parts of melamine polyphosphate, 20.6 - 46.7 parts of fly ash, 3 - 23.2 parts of ammonium dihydrogen phosphate, 5 - 11.5 parts of calcium silicate, and 3.3 - 20 parts of montmorillonite. It has the characteristics of good explosion suppression effect, high explosion suppression efficiency and environmental protection. It is particularly suitable for suppressing the explosion of coal dust in coal mines. Each material constituting the powder explosion inhibitor for suppressing coal dust explosion plays a role from different explosion suppression mechanisms, and various materials act synergistically to finally achieve the purpose of explosion suppression under various comprehensive effects. Fly ash is produced in large quantities in the coal industry production and pollutes the environment. Adding it to the composite explosion inhibitor can be recycled, making it more environmentally friendly.

Description

Technical Field

[0001] The present invention relates to a composite explosion suppressant for suppressing coal dust explosion, and the present invention also relates to a preparation method of the composite explosion suppressant for suppressing coal dust explosion. Background Art

[0002] In the coal powder preparation and storage equipment in mines, coal chemical industry, thermal power and metallurgical industries, there is accumulated coal powder. Once the coal powder forms a dust cloud, there will be an explosion risk that cannot be ignored. Once an explosion occurs, it will cause casualties and property losses, seriously threatening the safety production of the coal industry. For coal dust explosion, explosion suppression technology is one of the effective means to reduce the consequences of explosion accidents, and powder explosion suppressants are explosion suppressants with relatively good comprehensive effects. At present, in the coal industry, rock powder is often spread to play an explosion suppression role, but the explosion suppression effect of rock powder is not very ideal. Therefore, it is necessary to develop a new type of composite explosion suppressant.

[0003] CN102562123A discloses a mine high-explosion coal dust inhibitor, which is prepared from aluminum hydroxide, diatomite, and ammonium polyphosphate. The preparation method is to crush and mix all raw materials. For the explosion suppressant prepared using it, the explosion suppressant and coal dust are added at least in a ratio of 0.25:1 to completely suppress the generation of explosion.

[0004] CN106089288A discloses a preparation method of an endothermic modified potassium dihydrogen phosphate explosion suppressant. By compounding sodium alginate and liquid paraffin, and through homogenization, it is effectively coated on the surface of the explosion suppressant to form a microsphere structure that can absorb heat and melt. When the heat release of the explosive intensifies, it effectively absorbs heat and melts and effectively suppresses explosion, preventing explosive accidents caused by sudden heat release of explosive substances. The endothermic modified potassium dihydrogen phosphate explosion suppressant prepared by this method can withstand a maximum temperature of 285 - 300 °C. Summary of the Invention

[0005] In view of the above problems, the first object of the present invention is to provide another composite explosion suppressant for suppressing coal dust explosion in coal seams, and the second object is to provide a preparation method of the composite explosion suppressant for suppressing coal dust explosion. It can effectively absorb the heat in coal dust explosion, interrupt the chemical chain of the explosion reaction, can coat the surface of coal dust to reduce the coal dust concentration, and can isolate the contact between coal dust and air, so that explosion is difficult to occur through various synergistic effects, and the raw materials are easily available.

[0006] To achieve the above object, the technical solution of the present invention is: a composite explosion suppressant for suppressing coal dust explosion, characterized in that it is made from the following raw materials by weight fraction: 15.6 - 40 parts of melamine polyphosphate, 20.6 - 46.7 parts of fly ash, 3 - 23.2 parts of ammonium dihydrogen phosphate, 5 - 11.5 parts of calcium silicate, and 3.3 - 20 parts of montmorillonite.

[0007] When a coal dust explosion occurs, a powder explosion suppressant for suppressing coal dust explosion is ejected. When the explosion combustion flame meets the composite explosion suppressant, melamine polyphosphate decomposes first, and the initial decomposition path is as follows:

[0008] HN 2 +HO→N 2 +H 2 O

[0009] H+HO→H 2 O

[0010] HN 2 +HN 2 O→N 2 +N 2 +H 2 O

[0011] HN 2 O+H→N 2 +H 2 O

[0012] CHN 2 +HO→H 2 O+CN 2

[0013] CH 2 N 2 O+H→CHN 2 +H 2 O

[0014] HO+CHO 2 →H 2 O+CO 2

[0015] N 2 +H 2 N+HO→H 2 O+HN 3

[0016] HN 5 →N 2 +HN 3

[0017] HN 7 →N 2 +N 2 +HN 3

[0018] It can be seen from the decomposition path that melamine polyphosphate first decomposes into H 2 O, CO 2 and N 2 ,H 2O absorbs the heat in the high-temperature zone and turns into gaseous water, which can effectively reduce the temperature of the chemical reaction zone, thereby slowing down the further combustion and decomposition of pulverized coal, and generating CO 2 and N 2 are inert gases that can isolate air, reduce the oxygen concentration, and slow down the pulverized coal combustion reaction. As the temperature rises, melamine polyphosphate will further react, combine with free radicals such as O₂, HO·, and H· decomposed from oxygen and pulverized coal to form inert substances that are not easily combustible, thereby achieving the flame retardant purpose.

[0019] O 2 +N → NO 2

[0020] O 2 +CN 2 → CNO 2 O 2

[0021] CH₃N₃ 2 +O₂ 2 → CH₃N₃O₂ 2 O 2

[0022] O 2 +N₂ 4 → N₂O 2 +N₂ 2 O 2

[0023] HNO₂ 4 +O₂ 2 → 2NO₂ 2 +H₂O 2

[0024] HNO₂ 2 +H⁺ → NO 2 +H₂O 2 O

[0025] N₂ 2 +H⁺+O₂ → HNO₂ 2 O

[0026] H₂O₂ 2 +H⁺ → H₂O 2 +OH 2

[0027] HNO₂ 4 +H₂O₂ → NO₂ 2 +NO 2 +H₂O 2 O

[0028] N₂ 2 +H⁺ 2 +O₂ 3 P + H₂O₂ → HPO₃ 3 +H⁺ 2 +O₂4 P

[0029] Meanwhile, when melamine polyphosphate decomposes under high temperature, many solid substances with good thermal stability will be produced, which can adhere to the pulverized coal, absorb external heat, isolate external air, and play a protective role for the unburned pulverized coal, resulting in incomplete combustion of the pulverized coal. From the above decomposition process of melamine polyphosphate, it can be found that this substance has multiple reaction processes, and the complexity of its reaction process can very efficiently absorb the heat, free radicals and oxygen in the air during the combustion of pulverized coal. The solid inert high-temperature resistant substances generated by the reaction can adhere to the surface of the unburned pulverized coal and play a protective role again. Therefore, this substance has a high flame retardancy efficiency.

[0030] N 2 +H 2 NO 2 P → HPO + HN 3 O

[0031] H 6 O 7 P 2 +O + N 2 O → HPO + 3HO + H 2 N 2 O 5 P

[0032] HN 2 +H 2 NO + H 3 O 6 P 2 →H 2 N 2 O + H 3 NO 2 +HPO + O 3 P

[0033] The metal hydroxides in fly ash will decompose into water and inert metal oxides under high temperature. The inert metal oxides will adhere to the unburned pulverized coal to block air and isolate heat. The liquid water produced by the high-temperature decomposition of calcium silicate absorbs the heat generated during the explosion and evaporates into water vapor. It will also cause the coal dust particles to agglomerate. The agglomerated coal dust particles will quickly settle under the action of gravity, effectively reducing the concentration of coal dust in the air. Moreover, the generation of water vapor can increase the minimum explosion concentration (MEC) of coal dust, and finally reduce the concentration of coal dust in the air below the minimum explosion concentration (MEC) of coal dust, terminating the coal dust explosion.

[0034] Calcium silicate in the composite explosion suppressant in the present invention has good fluidity, which can prevent the composite explosion suppressant from caking. Montmorillonite can prevent the composite explosion suppressant from getting damp and coagulating.

[0035] In the composite explosion suppressant of the present invention, each component acts synergistically. On the one hand, it can effectively absorb the heat in the coal dust explosion and interrupt the chemical chain of the explosion reaction. On the other hand, it can coat the surface of the coal dust to reduce the coal dust concentration and isolate the contact between the coal dust and the air, thereby making it difficult for the explosion to occur through various synergistic effects.

[0036] The main chemical reaction equations involved are as follows:

[0037] HN 2 +HO→N 2 +H 2 O

[0038] H+HO→H 2 O

[0039] HN 2 +HN 2 O→N 2 +N 2 +H 2 O

[0040] HN 2 O+H→N 2 +H 2 O

[0041] CHN 2 +HO→H 2 O+CN 2

[0042] CH 2 N 2 O+H→CHN 2 +H 2 O

[0043] HO+CHO 2 →H 2 O+CO 2

[0044] N 2 +H 2 N+HO→H 2 O+HN 3

[0045] HN 5 →N 2 +HN 3

[0046] HN 7 →N 2 +N 2 +HN 3

[0047] O 2 +N→NO 2

[0048] O 2 +CN 2 →CN 2 O 2

[0049] CHN 2 +O 2 →CHN 2 O 2

[0050] O 2 +N 4 →N 2 +N 2 O 2

[0051] HN 4 +O 2 →2N 2 +HO 2

[0052] HN 2 O+H→N 2 +H 2 O

[0053] N 2 +H+O→HN 2 O

[0054] HO 2 +H→H 2 O 2

[0055] HN 4 +HO→N 2 +N 2 +H 2 O

[0056] N 2 +H 2 O 3 P+HO→H 3 N 2 O 4 P

[0057] N 2 +H 2 NO 2 P→HPO+HN 3 O

[0058] H 6 O 7 P 2 +O+N 2 O→HPO+3HO+H 2 N 2 O 5P

[0059] HN 2 +H 2 NO + H 3 O 6 P 2 →H 2 N 2 O + H 3 NO 2 +HPO + O 3 P

[0060] Preferably, it is composed of the following components by weight fraction: 15.6 - 20.8 parts of melamine polyphosphate, 20.6 - 28.3 parts of fly ash, 17.4 - 23.2 parts of ammonium dihydrogen phosphate, 8.5 - 11.5 parts of calcium silicate, and 9.6 - 14.4 parts of montmorillonite.

[0061] In the above scheme: the particle sizes of the melamine polyphosphate, fly ash, ammonium dihydrogen phosphate, calcium silicate, and montmorillonite are all less than 75 μm.

[0062] The second object of the present invention is achieved as follows: A preparation method of the composite explosion suppressant for suppressing coal dust explosion, characterized in that it is prepared according to the following method:

[0063] 1) Put the melamine polyphosphate, fly ash, ammonium dihydrogen phosphate, calcium silicate, and montmorillonite into a crusher to crush them, and use a 200 - mesh sieve to screen the crushed materials, and collect the screened powders respectively;

[0064] 2) Weigh the powders and put them into a dry powder mixer to stir, and obtain a uniformly mixed composite explosion suppressant;

[0065] 3) Place the composite explosion suppressant in an electro - thermal constant - temperature vacuum drying oven to dry to obtain the product.

[0066] In step 1), the crushing time is not less than 30 min.

[0067] In step 2), the stirring time is 20 - 30 min.

[0068] In the above scheme: drying is carried out using a vacuum drying oven, the drying temperature is 50 °C, and the drying time is 12 h.

[0069] Compared with the prior art, the beneficial effects of the present invention are as follows: It has the characteristics of good explosion suppression effect, high explosion suppression efficiency, and environmental protection. It is especially suitable for suppressing the explosion of coal dust in coal mines. The various materials that make up the powder explosion suppressant for suppressing coal dust explosion play roles from different explosion suppression mechanisms respectively, and the various materials act synergistically, and finally achieve the purpose of explosion suppression under various comprehensive actions. Fly ash is produced in large quantities in the coal industry production and pollutes the environment. Adding it to the composite explosion suppressant can be reused, which is more environmentally friendly. DETAILED DESCRIPTION

[0070] The present invention will be further described below by way of examples:

[0071] Examples 1-3

[0072] The composite explosion suppressant for suppressing coal dust explosion is made of melamine polyphosphate, fly ash, diammonium phosphate, calcium silicate and montmorillonite.

[0073] The weight fraction of each component is shown in Table 1

[0074]

[0075] The particle sizes of melamine polyphosphate, fly ash, diammonium phosphate, calcium silicate and montmorillonite are all less than 75 μm.

[0076] Prepare as follows:

[0077] 1) Put melamine polyphosphate, fly ash, ammonium dihydrogen phosphate, calcium silicate and montmorillonite into a pulverizer and grind them for not less than 30 minutes. Use a 200-mesh sieve to sieve the pulverized materials and collect the sieved powders respectively.

[0078] 2) Weigh the powder and put it into a dry powder mixer for stirring for 20-30 minutes to obtain a uniformly mixed composite explosion suppressant.

[0079] 3) The composite explosion suppressant is placed in an electric constant temperature vacuum drying oven to dry the product at a drying temperature of 50°C and a drying time of 12 hours.

[0080] Take three kinds of coal samples, and carry out explosion suppression test on Examples 1-6 and the comparative example, and the minimum explosion suppression amount is shown in Table 2.

[0081]

[0082] It can be seen from Table 2 that the minimum amount of explosion suppression required by the present invention is reduced by almost half compared with rock powder.

[0083] The present invention is not limited to the above-mentioned embodiments. Those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A composite explosion inhibitor for suppressing coal dust explosion, characterized in that, it is made of the following raw materials by weight fraction: 15.6 - 40 parts of melamine polyphosphate, 20.6 - 46.7 parts of fly ash, 3 - 23.2 parts of ammonium dihydrogen phosphate, 5 - 11.5 parts of calcium silicate, and 3.3 - 20 parts of montmorillonite.

2. The composite explosion inhibitor for suppressing coal dust explosion according to claim 1, characterized in that, it is composed of the following components by weight fraction: 15.6 - 20.8 parts of melamine polyphosphate, 20.6 - 28.3 parts of fly ash, 17.4 - 23.2 parts of ammonium dihydrogen phosphate, 8.5 - 11.5 parts of calcium silicate, and 9.6 - 14.4 parts of montmorillonite.

3. The composite explosion inhibitor for suppressing coal dust explosion according to claim 1 or 2, characterized in that: the particle sizes of the melamine polyphosphate, fly ash, ammonium dihydrogen phosphate, calcium silicate, and montmorillonite are all less than 75 μm.

4. A preparation method of the composite explosion inhibitor for suppressing coal dust explosion according to any one of claims 1 - 3, characterized in that, it is prepared according to the following method: 1) Put the melamine polyphosphate, fly ash, ammonium dihydrogen phosphate, calcium silicate, and montmorillonite into a pulverizer to pulverize them, and use a 200 - mesh sieve to screen the pulverized materials, and collect the screened powders respectively; 2) Weigh the powders and put them into a dry powder mixer to stir, and obtain a uniformly mixed composite explosion inhibitor; 3) Place the composite explosion inhibitor in an electro - thermal constant - temperature vacuum drying oven to dry to obtain the product.

5. The preparation method of the composite explosion inhibitor for suppressing coal dust explosion according to claim 4, characterized in that: in step 1), the pulverizing time is not less than 30 min.

6. The preparation method of the composite explosion inhibitor for suppressing coal dust explosion according to claim 5, characterized in that: in step 2), the stirring time is 20 - 30 min.

7. The preparation method of the composite explosion inhibitor for suppressing coal dust explosion according to claim 6, characterized in that: the drying temperature is 50 °C and the drying time is 12 h.

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