AU2018403914B2

AU2018403914B2 - Efficient, green and environmental friendly extinguishing agent and preparation method thereof

Info

Publication number: AU2018403914B2
Application number: AU2018403914A
Authority: AU
Inventors: Junming Chen; Jiahao GUO; Wei Li; Jie Mao; Xuchun WANG; Jiayu YAN; Xiangju YE; Ting Zhang; Xuemei Zhang
Original assignee: Anhui University of Science and Technology
Current assignee: Anhui University of Science and Technology
Priority date: 2018-06-12
Filing date: 2018-08-09
Publication date: 2020-02-13
Anticipated expiration: 2038-08-09
Also published as: AU2018403914A1; CN108619651A; WO2019237482A1

Abstract

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Description

EFFICIENT, GREEN AND ENVIRONMENTAL FRIENDLY

EXTINGUISHING AGENT AND PREPARATION METHOD THEREOF

TECHNICAL FIELD

The present invention belongs to the technical field of extinguishment, and particularly, relates to an efficient, green and environmental friendly extinguishing agent and a preparation method thereof.

BACKGROUND

Fire hazard has always been the enemy of mankind. Since ancient times, whether it is a natural fire or an accident fire, on one hand, it has caused a lot of natural resources and property losses. On the other hand, human beings have also suffered. At present, extinguishing agents have spread all over the comers of human production and life, and the annual consumption is huge. Since its development, the variety has varied and has its own advantages and disadvantages. The various extinguishing agent products widely used in the world have more or less disadvantages in terms of conditions of use, scope of application, environmental protection and extinguishing performance, and the suppression of smoke caused by fire is very limited.

Halon extinguishing agent is the most typical representative. Halon extinguishing agent has the characteristics of high extinguishing efficiency, low dosage, good space submergence and chemical stability, non-conductivity, low corrosiveness and toxicity. It can be used to save a variety of fires, but it is not easy to decompose, and it will generate a substance that destroys the ozone layer of the atmosphere and seriously consumes ozone in the atmosphere, posing a huge threat to human health and the ecological environment. According to international conventions, China has completely abolished the use of such extinguishers.

Nowadays, the common halon series extinguishing agent substitutes are heptafluoropropane gas i

2018403914 20 Dec 2019 extinguishing agent, carbon dioxide extinguishing agent, high-pressure storage tank type, low-pressure multi-component, low-pressure pump station type water mist extinguishing system, K and S types hot aerosol extinguishing devices. Then there is the ultra-fine dry powder extinguishing agent. Although the former extinguishing agents have been developed rapidly as substitutes of halon extinguishing agent, the solid extinguishing agents widely used on the market are still dry powder extinguishing agents for many reasons.

The dry powder extinguishing agent is composed of one or more fine inorganic powders having extinguishing ability. The extinguishing mechanism is that the extinguishing agent covers the surface of the combustible material, and the combustible material is blocked from contact with oxygen in the air, so that the combustion cannot be maintained and extinguished. However, common dry powder extinguishing agents also have their inevitable shortcomings, such as low melting point, being easily damped, particle size limitation, high production cost, and little effect on liquid fire.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

SUMMARY

It is an aim of at least a preferred embodiment of the present disclosure to provide a green and environmental friendly extinguishing agent having a high extinguishing efficiency, which breaks a current deadlock on the market, the absence of an extinguishing agent that can balance the extinguishing effect, range of application, environmental protection and economic benefit.

It is an aim of at least a preferred embodiment of the present disclosure to provide a preparation method of an efficient, green and environmental friendly extinguishing agent.

Another aim of at least a preferred embodiment of the present disclosure is to provide an extinguishing agent prepared.

2018403914 20 Dec 2019

Disclosed herein is a preparation method of an efficient, green and environmental friendly extinguishing agent is as follows: sufficiently grinding and mixing sodium dihydrogen phosphate, ammonium bicarbonate and a pulverization assistant; then adding white carbon black (micro-nano silicon dioxide) and sufficiently grinding and mixing; then adding silicone oil, heating with stirring, and maintaining at a constant temperature for a period of time to obtain a white carbon black extinguishing agent coated with a silicone oil film.

Preferably, the pulverization assistant is sodium carbonate.

Preferably, the white carbon black is silicon dioxide having a particle size between micron size and nano size, including micron size and nano size, for example, silica sands in micron size or nano size.

Preferably, the silicone oil is dimethyl silicone oil.

Preferably, a mass ratio of sodium dihydrogen phosphate to ammonium bicarbonate to the pulverization assistant to white carbon black is 4 - 6: 1.5-3: 2-3: 0.5-1.5.

Preferably, a ratio of a total amount of sodium dihydrogen phosphate, ammonium bicarbonate, the pulverization assistant and white carbon black to an amount of the silicone oil is 0.5 - 1.0 ml: 10 g.

Preferably, the maintaining at a constant temperature for a period of time is to maintain at 100°C 105°C for 2 - 3 hours.

Additionally particularly, as a preferable embodiment, the preparation method comprises the following steps:

(1) mixing sodium dihydrogen phosphate, ammonium bicarbonate and the pulverization assistant, then grinding and sieving, and controlling a particle size between 200 and 300 mesh to obtain a first mixture;

(2) adding the white carbon black to the first mixture, sufficiently mixing followed by grinding and sieving, and controlling a particle size between 300 and 400 mesh to obtain a second mixture;

2018403914 20 Dec 2019 (3) adding the silicone oil to the second mixture, and mixing uniformly to form a third mixture; and (4) maintaining the third mixture at 100°C - 105°C for 2 - 3 hours to obtain the white carbon black extinguishing agent.

In particular preferably, the grinding in steps (1) and (2) lasts for 1 to 2 hours.

In addition, the extinguishing agent prepared by the aforementioned method shall also be within the scope of protection of the present invention. The obtained extinguishing agent has a particle size ranging from 2 pm to 70 pm.

In order to briefly describe the technical problem, the preparation method of an efficient, green and environmental friendly extinguishing agent in the present invention is abbreviated to “the method”.

White carbon black is the soul of the extinguishing agent of the present invention. The white carbon black used in the present invention is a hydrophobic white carbon black, silicone dioxide in micron size or nano size, having a structure in porous amorphous form and presenting as white powder. The particle size of a single particle is rather small, and a bulk density is very low. Such characteristics give an excellent space-fdling property for the product. White carbon black possesses good high-temperature resistance, electrical insulating property, oil resistance, chemical stability and environmental friendliness, being tasteless, odorless, non-toxic, and noncombustible, and it can be returned to soil. As an environmental friendly material with excellent performances, the white carbon black plays the main role in the method, for it has an ultra-high specific surface area with an extremely large adsorption capacity which can significantly enhance a suspension rate of the final product, so that the extinguishing agent product can suspend on the surface of liquid and maintain a durable effectiveness when facing a liquid fire hazard, and it tends to form an oxygen-isolated film during suspension, having good oxygen-isolated property, high-temperature resistance and chemical stability.

The sodium dihydrogen phosphate used in the method is an analytical pure reagent in which each molecule contains two crystal waters, has a density of 1.949 g/cm³ and a melting point of 60°C. The

2018403914 20 Dec 2019 sodium dihydrogen phosphate is very soluble in water but insoluble in alcohols, forms caking in humid air and is dehydrated crystal water at 100°C to become an anhydrous substance. As the temperature increases, several reactions occur on the sodium dihydrogen phosphate. An aqueous solution thereof is acidic.

The ammonium bicarbonate used in the method is a white compound in a form of columnar crystal with ammonium odour. It generates carbon dioxide and water when reacting with acid. Since an aqueous solution of the sodium dihydrogen phosphate is acidic, by utilizing such property, the method makes the ammonium bicarbonate and the aqueous solution of sodium dihydrogen phosphate react with each other at high temperature to generate carbon dioxide and water which are beneficial to extinguishment and exert an important effect. This reaction is endothermic, and thus it can not only suppress the fire but also decrease a temperature of the scene of a fire.

The sodium carbonate used in the method mainly serves as a pulverization assistant which assists more sufficient grinding of raw materials during the grinding process to obtain a product with smaller and more uniform particle size. Also, a decomposed product of sodium carbonate is endothermic, and the carbon dioxide generated is favorable to extinguishment.

The silicone oil used in the method is dimethyl silicone oil, a hydrophobic organosilicone material, being colorless and transparent viscous liquid in general state, and tasteless, odorless, and non-toxic. It has excellent hydrophobic moisture resistance, good transparency and chemical stability. By utilizing its excellent hydrophobic moisture resistance, chemical stability and heat resistance, the dimethyl silicone oil in the method serves as a surface treating agent and forms a film layer on the particle surface of the extinguishing agent powder at a certain temperature, so that the extinguishing agent has good oxygen-isolated property, hydrophobicity, heat resistance and chemical stability.

In the method, a novel white carbon black extinguishing agent is prepared using these aforementioned components as raw materials. It can be seen from a water solubility test that the white carbon black extinguishing agent has flexible water solubility. It can float on the liquid surface for a long term in general circumstances, and remain insoluble for a while after being stirred and

2018403914 20 Dec 2019 drowned into liquid, which provides a significant advantage for extinguishment to liquid fire hazard. After a long time, the extinguishing agent tends to be dissolved in liquid so as to reduce harm to the environment. In a differential thermal analysis (DTA) and a thermogravimetric analysis (TG), it can be seen from the differential thermal curve and the thermogravimetric curve that the white carbon black extinguishing agent was decomposed in multiple stages at high temperature, and generated CO2 that suppresses the fire. Since the decomposition reaction is an endothermic reaction, it can effectively decrease the temperature of a scene of fire. When the temperature reaches above 500°C, the white carbon black extinguishing agent is no longer decomposed and tends to be stable, indicating the high-temperature resistance of the white carbon black. It can be found by a laser particle size test that 97.36% of particle size of the white carbon black sample is below 39.23 pm. The extinguishing performance of a dry powder extinguishing agent is inversely proportional to the particle size, the smaller the particle size, the bigger the specific surface area and the fire contact area, and the stronger the adhesive ability. After being sprayed, the extinguishing agent forms an aerosol in the space to isolate the air, favorable to the extinguishment. It can be seen from an extinguishing performance test that in the same condition, both an extinguishing time and an extinguishing amount of the white carbon black extinguishing agent are far less than those of the general extinguishing agent without white carbon black. What’s more, the white carbon black extinguishing agent can effectively suppress the fire smoke. Thus, the white carbon black extinguishing agent of the present invention has an apparently better extinguishing performance, and an extinguishing efficiency more than twice the general extinguishing agent without white carbon black, with cheaper raw materials and maintaining environmental friendly before and after extinguishment.

The present invention has the following beneficial effects:

An efficient, green and environmental friendly extinguishing agent developed by the present invention can overcome various drawbacks of the current extinguishing agents on the market, and break a current deadlock on the market, the absence of an extinguishing agent that can balance the extinguishing effect, range of application, environmental protection and economic benefit. A novel extinguishing agent which can be used widely, with an outstanding extinguishing effect but without negative influence on environment, is obtained. The extinguishing agent exerts excellent

2018403914 20 Dec 2019 extinguishing effect on three types of fire hazards (solid type, liquid type, air type), and properties thereof such as moisture resistance, caking resistance, rebum resistance and environmental friendliness are better than other extinguishing agents on the current market.

The white carbon black fire extinguishing agent of the present invention not only has high extinguishing efficiency (easy to form an oxygen-isolated film), but also has the characteristics of high-temperature resistance, hydrophobicity and moisture resistance, and caking resistance, environmental protection and low production cost compared with the general extinguishing agents. It is bound to have a good market environment and development prospects, which is in line with the scientific development concept and the green development concept, and will certainly produce considerable economic and environmental benefits.

Throughout this specification the word comprise, or variations such as comprises or comprising, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a differential thermal curve of an extinguishing agent prepared by the method.

FIG. 2 is a thermogravimetric curve of the extinguishing agent prepared by the method.

FIG. 3 is a particle size distribution curve of the extinguishing agent prepared by the method.

FIG. 4 is a X-ray diffraction spectrum of the extinguishing agent prepared by the method.

DETAILED DESCRIPTION

The present invention is further described by the accompanied drawings and specific examples, but the examples do not limit the present invention in any ways. Unless specified, reagents, methods and instruments used in the present invention are conventional reagents, methods and instruments in the

2018403914 20 Dec 2019 art.

Unless specified, reagents and materials used in the following examples are commercially available.

Example 1

A preparation method of an efficient, green and environmental friendly extinguishing agent, comprises the following steps:

(1) 4 g of sodium dihydrogen phosphate dihydrate, 1.5 g of ammonium bicarbonate and 2 g of sodium carbonate were mixed and added to an agate mortar, then grinded for 1 hour and sieved, a particle size was controlled between 200 and 250 mesh, and a first mixture was obtained;

(2) 0.5 g of micron size or nano size silicon dioxide was added to the first mixture and sufficiently mixed, then grinded for 1 hour and sieved, the particle size was controlled between 300 and 350 mesh, and a second mixture was obtained;

(3) a dimethyl silicone oil was added to the second mixture, with an additive ratio of 0.05 ml of dimethyl silicone oil every 1 g of the second mixture, after uniform mixing, a third mixture was obtained;

(4) the third mixture was put in an electronic temperature-constant air dry oven for maintaining at a set temperature of 100°C for 2 hours, and then taken out. The extinguishing agent was obtained with a particle size of 2 to 70 pm.

Example 2

(1) 5 g of sodium dihydrogen phosphate dihydrate, 2.25 g of ammonium bicarbonate and 2.5 g of sodium carbonate were mixed and added to an agate mortar, then grinded for 1.5 hour and sieved, a particle size was controlled between 230 and 270 mesh, and a first mixture was obtained;

(2) 1.0 g of micron size or nano size silicon dioxide was added to the first mixture and sufficiently

2018403914 20 Dec 2019 mixed, then grinded for 1.5 hour and sieved, the particle size was controlled between 330 and 370 mesh, and a second mixture was obtained;

(3) a dimethyl silicone oil was added to the second mixture, with an additive ratio of 0.075 ml of dimethyl silicone oil every 1 g of the second mixture, after uniform mixing, a third mixture was obtained;

(4) the third mixture was put in an electronic temperature-constant air dry oven for maintaining at a set temperature of 102.5°C for 2.5 hours, and then taken out. The extinguishing agent was obtained with a particle size of 2 to 70 pm.

Example 3

(1) 6 g of sodium dihydrogen phosphate dihydrate, 3 g of ammonium bicarbonate and 3 g of sodium carbonate were mixed and added to an agate mortar, then grinded for 2 hours and sieved, a particle size was controlled between 250 and 300 mesh, and a first mixture was obtained;

(2) 1.5 g of micron size or nano size silicon dioxide was added to the first mixture and sufficiently mixed, then grinded for 2 hours and sieved, the particle size was controlled between 350 and 400 mesh, and a second mixture was obtained;

(3) a dimethyl silicone oil was added to the second mixture, with an additive ratio of 0.1 ml of dimethyl silicone oil every 1 g of the second mixture, after uniform mixing, a third mixture was obtained;

(4) the third mixture was put in an electronic temperature-constant air dry oven for maintaining at a set temperature of 105°C for 3 hours, and then taken out. The extinguishing agent was obtained with a particle size of 2 to 70 pm.

Example 4 Performance Tests

Performances of the extinguishing agent of the present invention were tested using samples prepared

2018403914 20 Dec 2019 in Example 2.

1. Experiment Instruments

AR-1140 Electronic analytical balance: Mettler Toledo (Shanghai).

GZX-9076-MBE Electronic temperature-constant air dry oven: Shanghai Boxun Industry Ltd.

Bettersize-2000 Laser particle size distribution analyzer: Bettersize Instruments Ltd.

XD-3 X-ray powder diffractometer: Beijing Persee Instrument Ltd.

JJ-1 Motor stirrer: Jiangsu Jintan Jincheng Guosheng Experiment Instrument Ltd.

Agate mortar, grinding rod, beaker.

2. Water-solubility Test

It is a great manifestation of environmental protection performance that whether the extinguishing agent is soluble in water. Dry powder extinguishing agents will have a large amount of powder remaining after use, and if they are insoluble, they will have an adverse effect on the environment. Therefore, the dry powder extinguishing agent should have the property of floating on the surface of common flammable liquid and being not easily dissolved in a short time, and can be dissolved after a long time.

In the water-solubility test, three types of liquid common in life (water, ethanol and edible oil, respectively) served as test objects. 60 ml of distilled water, ethanol and edible oil were respectively added to three 100 ml beakers. 5 g of sample powder was weighed and evenly sprayed on the surfaces of the three types of liquid. Start timing, observing and recording the floating conditions of the powder on the three liquid surfaces and the time required for being dissolved after sinking into the liquid. The test results are shown as Table 1.

Table 1: Performance manifestations of the extinguishing agent in three types of liquid

	water	ethanol	edible oil
Floating time (without	always floating	always floating	always floating

io

2018403914 20 Dec 2019

stirring)
Dissolving time	> 3 hours	> 3 hours	insoluble

Under a synergy effect of the white carbon black and the silicone oil, without stirring, it can be seen that the extinguishing agents can keep floating on the three types of liquid, being favorable to form an oxygen-isolated extinguishing film. After stirring, the extinguishing agents sunk into the liquid and to the bottom of the liquid, but without apparent dissolution. 3 hours later, the water and ethanol became turbid which meant that the extinguishing agents started to be dissolved. 6 hours after the test begun, the extinguishing agents were substantially dissolved, with merely little residues visible in the liquid which was found to be silicon dioxide, i.e. white carbon black, through collection and detection. A majority of the extinguishing agent was randomly dispersed in the edible oil without apparent dissolution.

In conclusion, the sample powder has good water solubility. It would not be dissolved in the liquid immediately at the beginning of extinguishing and would form an oxygen-isolated film which effectively exerts an extinguishing effect. After quite a long time, the sample powder is easily to be dissolved and there’s no large amount of residues that influence the environment. That is to say, the extinguishing agent prepared by the present invention has an excellent performance in water solubility.

3. Thermogravimetric analysis and differential thermal analysis of the extinguishing agent

Thermal decomposition status and endothermic and exothermic status were evaluated as an important indicator of extinguishing performance of an extinguishing agent. Test methods of the differential thermal analysis and the thermogravimetric analysis are as follows: approximately 10 mg of the sample was weighed in a small crucible, and after a contrastive analysis through a thermogravimetric analyzer, a differential thermal curve and a thermogravimetric curve of the extinguishing agent sample were obtained. Then, the thermogravimetry status and the endothermic and exothermic status of the extinguishing agent in thermal decomposition at high temperature were obtained according to the thermogravimetric analysis and the differential thermal analysis.

Through a thermogravimetric analysis of the extinguishing agent sample prepared by the method, a differential thermal analysis (DTA) curve and a thermogravimetric (TG) curve of the sample were obtained. Results are shown as FIG. 1 and FIG. 2, and it can be seen from the TG curve that a first

2018403914 20 Dec 2019 landslide is presented at 170°C, which means the ammonium bicarbonate started to be decomposed. At the same time, it can be seen from the DTA curve that an obvious endothermic peak is presented indicating that the sample absorbed heat from the outside during decomposition. At 310°C, another landslide is presented in the TG curve, while the sodium dihydrogen phosphate was decomposed and an endothermic peak is also presented simultaneously in the DTA curve. Above 500°C, the TG curve of the sample remains steady due to high-temperature resistance of the white carbon black, indicating that the sample was no longer decomposed having good high-temperature resistance.

It can be concluded from the results that at the scene of fire, the extinguishing agent sample was subjected to multistage decomposition at high temperature and generated carbon dioxide gas and vapor that suppress the fire. Meanwhile heat of the scene of fire was absorbed and temperature of the scene of fire decreased. When the temperature reached above 500°C, micron and nano particles of silicon dioxide in the sample are no longer decomposed, so as to be effectively used as high-temperature extinguishing agent.

Therefore, after the differential thermal analysis and the thermogravimetric analysis, the extinguishing agent sample prepared by the method can be efficiently used for high-temperature extinguishing demand caused by oil and electricity.

4. Particle size distribution of the extinguishing agent sample

Particle size test method: a certain amount of the powder sample of extinguishing agent was weighed and subjected to a particle size analysis via a laser particle size tester. It should be noted that the sample was coated with a thin layer of silicone oil film on the surface, thus having certain hydrophobicity. Therefore, stirring with a glass rod was kept when adding the sample, so as to accelerate dispersion of the powder sample in water and to complete the particle size analysis. According to the test result, particle size distribution of the powder sample was obtained.

The particle size distribution of the powder sample of extinguishing agent prepared by the present invention was tested through the laser particle size tester and shown as FIG. 3. In FIG. 3, the horizontal ordinate represents the particle size, and the vertical ordinate represents percentage contents corresponding to different particle sizes. It is well known that the particle size of a chemical extinguishing agent is inversely proportional to the extinguishing efficiency. It can be clearly seen from FIG. 3 that 97.36% of particle size of the sample is below 39.23 pm. When the particle size is

2018403914 20 Dec 2019 small, a specific surface area large and a contact area between the powder particles and the fire are large, resulting in a rather strong absorbing capacity of the powder to the fire heat. Cooperating with the effect of nano white carbon black, the smaller the particle mass, the stronger the activity, and through pressurized spraying, a relatively stable aerosol film is formed and distributed evenly in a protection space, so that oxygen is isolated. Thus, the overall extinguishing efficiency is far higher than that of the common extinguishing agent.

5. X-ray diffraction spectrum of the powder sample of extinguishing agent

XRD test: a suitable amount of sample was picked with a spoon and added to a drug cuvette, after firm tableting, the sample was placed on a loading platform of an X-ray powder diffraction analyzer. Then the door was shut, and a computer analysis program was activated. An automatic scanning test was started right after analysis parameters were set, and then data was obtained when the scanning was finished. A diffraction spectrum of the sample could be obtained by processing the data, and composition of the sample was analyzed by comparing the diffraction spectrum with the standard card.

Results are shown in FIG. 4. The X axis represents diffraction angles, while the Y axis represents peak intensities. An XRD spectrum of silicon dioxide in the extinguishing agent sample prepared by the present invention is shown. It is found by comparing a PDF standard card and analysis that the sample shows characteristic diffraction peaks of silicon dioxide at (-110) crystal face (18.29°) and (010) crystal face (22.10°), after a baseline was processed via Jade. These two peaks are rather sharp, indicating that the micron and nano size silicon dioxide in the extinguishing agent sample has relatively high crystallinity.

6. Extinguishing performance test of the extinguishing agent

Extinguished objects to be tested are firewood and ethyl alcohol which were added with equivalent amount to stainless steel tubs and lit in the same condition. In the steady combustion, a common dry powder extinguishing agent and an extinguishing agent prepared by the present method which were prepared with the same concentration (300 g/L) were subjected to the extinguishing performance test with the same kind of spray guns. Test results are shown as Table 2.

Table 2: Extinguishing performance test results

2018403914 20 Dec 2019

Extinguishing agent	Combustible matter
80.0 g of firewood was burnt	55.0 g of ethyl alcohol was burnt
Common dry powder extinguishing agent 300 g/L	10-12 seconds	7-9 seconds
White carbon black extinguishing agent of the present invention 300 g/L	4-5 seconds	3-4 seconds

Compared with the extinguishing effect of the common extinguishing agent, the extinguishing agent prepared by the method has far less extinguishing time and extinguishing dosage than the common extinguishing agent. Besides, the white carbon black has high-temperature resistance, high specific surface energy and strong capability of film formation by nano adsorption, with more apparent suppression to fire smoke and oxygen-isolated effect, and therefore the extinguishing performance of the extinguishing agent prepared by the method is far better than that of the common extinguishing agent.

Example 5

Through a great deal of research experiments, major factors of the method that affect overall performance of the extinguishing agent are additive amounts of sodium dihydrogen phosphate, ammonium bicarbonate, sodium carbonate, white carbon black and silicone oil. mixing uniformity, particle size of the final extinguishing agent powder, and time and temperature for heating and maintaining, which would affect the overall performance of the sample particles.

Particularly, an additive ratio of sodium dihydrogen phosphate to ammonium bicarbonate to the pulverization assistant to the white carbon black to silicone oil is optimally controlled as 4 - 6 g: 1.5 - 3 g: 2 - 3 g: 0.5 - 1.5 g: 0.5 - 1.0 ml. Mixing uniformly is required. The particle size of the extinguishing agent powder is optimally controlled at 2 - 70 pm. Heating and maintaining are optimally conducted at 100 - 105°C for 2 - 3 hours.

The above examples are preferred implementations of the present invention which are not limited by the above examples. Any other changes, modifications, substitutions, combinations, and simplifications that are made without departing from the spirit and scope of the invention are intended to be equivalents and are included in the scope of protection of the invention.

Claims

What is claimed is:

(1) mixing sodium dihydrogen phosphate, ammonium bicarbonate and the pulverization assistant, then grinding and sieving, and controlling a particle size between 200 and 300 mesh to obtain a first mixture;

1. A preparation method of an efficient, green and environmental friendly extinguishing agent, characterized in that, sufficiently grinding and mixing sodium dihydrogen phosphate, ammonium bicarbonate and a pulverization assistant; then adding white carbon black and sufficiently grinding and mixing; then adding silicone oil, heating with stirring, and maintaining at a constant temperature for a period of time to obtain a white carbon black extinguishing agent coated with a silicone oil film.
(2) adding the white carbon black to the first mixture, sufficiently mixing followed by grinding and sieving, and controlling a particle size between 300 and 400 mesh to obtain a second mixture;

2. The preparation method according to claim 1, wherein the pulverization assistant is sodium carbonate.
(3) adding the silicone oil to the second mixture, and mixing uniformly to form a third mixture; and (4) maintaining the third mixture at 100°C - 105°C for 2 - 3 hours to obtain the white carbon black extinguishing agent.

3. The preparation method according to claim 1, wherein the white carbon black is silicon dioxide having a particle size between micron size and nano size.
4. The preparation method according to claim 1, wherein the silicone oil is dimethyl silicone oil.
5. The preparation method according to claim 1, wherein a mass ratio of sodium dihydrogen phosphate to ammonium bicarbonate to the pulverization assistant to white carbon black is 4 - 6: 1.5 -3: 2-3: 0.5-1.5.
6. The preparation method according to claim 1, wherein a ratio of a total amount of sodium dihydrogen phosphate, ammonium bicarbonate, the pulverization assistant and white carbon black to an amount of the silicone oil is 0.5 - 1.0 ml: 10 g.
7. The preparation method according to claim 1, wherein the maintaining at a constant temperature for a period of time is to maintain at 100°C - 105°C for 2 - 3 hours.
8. The preparation method according to any one of claims 1 to 7, wherein the preparation method comprises the following steps:
9. The preparation method according to claim 8, wherein the grinding in steps (1) and (2) lasts for 1 to 2 hours.
10. An extinguishing agent prepared by the method according to any one of claims 1 to 9.