A Class D dry powder fire extinguishing agent, its preparation method and its application

Abstract

The present invention relates to the field of powder fire extinguishing agents, and particularly to a Class D dry powder fire extinguishing agent, a preparation method thereof and an application thereof. The Class D dry powder fire extinguishing agent of the present invention comprises the following components in percentage by weight: 58-63% of sodium chloride; 25-35% of inorganic non-metallic powder; 4-10% of flow aid; 1-4% of moisture-proof agent; wherein, the preparation method of the inorganic non-metallic powder comprises: mixing 19-25% of silicon dioxide, 18-22% of boron trioxide and 57-63% of lead oxide in percentage by weight, melting and mixing evenly, water quenching, drying and ball milling to obtain the inorganic non-metallic powder. It effectively improves the powder fluidity of the Class D dry powder fire extinguishing agent, improves the compactness and hardness of the outer shell formed after the interaction with the combustible in the fire extinguishing process, thereby improving the wall adhesion effect of the Class D dry powder fire extinguishing agent to better cope with the wall surface at a certain angle to the horizontal plane, especially the magnesium fire on the vertical wall surface.

Description

Technical Field

[0001] The present invention relates to the field of powder fire extinguishing agents, and particularly to a Class D dry powder fire extinguishing agent, a preparation method thereof, and an application thereof. Background Art

[0002] Magnesium metal has advantages such as light weight, good corrosion resistance, good shock absorption, good impact resistance, and high dimensional stability. Magnesium and its alloy materials are widely used, especially in the fields of transportation (such as airplanes or automobiles), electronics industry, medical treatment, military industry, etc. China is a major producer and user of magnesium. However, magnesium metal is an inflammable and explosive dangerous substance, and the smaller its size, the greater the danger. Especially in factories involving magnesium cutting and polishing processes, the magnesium chips generated by cutting and the magnesium powder generated by polishing are highly flammable, and magnesium powder at a certain concentration even has the risk of causing dust explosion.

[0003] A magnesium fire refers to a fire caused by the combustion of magnesium metal or magnesium alloy. Magnesium can burn in air. Since magnesium can react with carbon dioxide, magnesium can continue to burn in carbon dioxide. Highly reactive magnesium can also react with nitrogen to form magnesium nitride. Therefore, the common method of using conventional inert gases such as carbon dioxide or nitrogen to extinguish fires is no longer applicable to magnesium fires. Magnesium metal can also react with water to generate hydrogen, intensifying the fire and even causing an explosion in severe cases, resulting in more serious accident consequences. At present, Class D dry powder fire extinguishing agents are usually used to deal with magnesium fires.

[0004] The existing Class D dry powder fire extinguishing agents are mainly divided into three types, and the corresponding base materials are sodium chloride, graphite, and sodium carbonate respectively. The dry powder fire extinguishing agent with sodium chloride as the base material is widely used for dealing with magnesium metal or its alloy fires. For example, the invention application with the publication number CN104069610A discloses a Class D dry powder fire extinguishing agent, which includes, by weight percentage: 45 - 50% of sodium chloride, 30 - 35% of potassium chloride, 2 - 4% of clay, 4 - 6% of mica, 5 - 8% of boron nitride, 4 - 5% of white carbon black, and 2 - 5% of high-boiling silicone oil. However, it is found in actual use that: the wall attachment performance of this Class D dry powder fire extinguishing agent is poor, and the fire extinguishing effect on the wall surface at a certain angle to the horizontal plane, especially the vertical wall surface, of a magnesium fire is poor. And magnesium alloy materials are widely used in positions such as the bracket structure of airplanes, the instrument panel of automobiles, and the seat frame, and there are many vertical wall surfaces. Once a fire occurs in these positions, it is very difficult to quickly extinguish the fire. Summary of the Invention

[0005] Aiming at the technical problems that the existing Class D dry powder fire extinguishing agent has poor wall attachment effect and poor fire extinguishing effect on the wall surface at a certain angle to the horizontal plane, especially the vertical wall surface, of a magnesium fire, the present invention adopts the following technical solutions:

[0006] On the one hand, a class D dry powder fire extinguishing agent is provided. The class D dry powder fire extinguishing agent, by weight percentage, comprises the following components: sodium chloride 58 - 63%; inorganic non-metallic powder 25 - 35%; flow aid 4 - 10%; moisture-proof agent 1 - 4%; wherein, the preparation method of the inorganic non-metallic powder comprises: mixing silicon dioxide at 19 - 25% by weight percentage, boron trioxide at 18 - 22% by weight percentage, and lead oxide at 57 - 63% by weight percentage, melting and mixing evenly, water quenching, drying and ball milling to obtain the inorganic non-metallic powder.

[0007] Further, the weight percentage of the inorganic non-metallic powder is 30 - 32%.

[0008] Further, the inorganic non-metallic powder, by weight percentage, comprises the following components: silicon dioxide 20%, boron trioxide 20%, and lead oxide 60%.

[0009] Further, the flow aid comprises at least one of molybdenum disulfide, magnesium stearate, talc powder, white carbon black or boron nitride.

[0010] Further, the flow aid, by weight percentage of the class D dry powder fire extinguishing agent, comprises the following components: molybdenum disulfide 3 - 5% and magnesium stearate 1 - 5%.

[0011] Further, the moisture-proof agent comprises silicone oil or high-boiling silicone oil.

[0012] On the other hand, a preparation method of a class D dry powder fire extinguishing agent is provided. The method comprises the following steps:

[0013] Prepare a saturated sodium chloride aqueous solution with a pH of 1: Configure sodium chloride at 58 - 63% by weight percentage of the class D dry powder fire extinguishing agent into a saturated sodium chloride aqueous solution under heating conditions, add acid to adjust the pH of the saturated sodium chloride aqueous solution to 1, and after cooling to room temperature, obtain a saturated sodium chloride aqueous solution with a pH of 1;

[0014] Prepare an alcohol dispersion of the inorganic non-metallic powder: Mix the inorganic non-metallic powder at 25 - 35% by weight percentage of the class D dry powder fire extinguishing agent, absolute ethanol and a dispersant, and ultrasonically vibrate to uniformly disperse the inorganic non-metallic powder in absolute ethanol to obtain an alcohol dispersion of the inorganic non-metallic powder; wherein, the preparation method of the inorganic non-metallic powder comprises: mixing silicon dioxide at 19 - 25% by weight percentage, boron trioxide at 18 - 22% by weight percentage, and lead oxide at 57 - 63% by weight percentage, melting and mixing evenly, water quenching, drying and ball milling to obtain the powder;

[0015] Preparation of inorganic non-metallic powder-coated sodium chloride particles: Rapidly drop the saturated sodium chloride aqueous solution with a pH of 1 into the alcohol dispersion of the inorganic non-metallic powder, and perform vacuum filtration; dry the obtained filter residue to obtain inorganic non-metallic powder-coated sodium chloride particles, denoted as A;

[0016] Preparation of dry powder fire extinguishing agent: Mix the A, a flow aid accounting for 4-10% by weight of the class D dry powder fire extinguishing agent, and a moisture-proof agent accounting for 1-4% by weight of the class D dry powder fire extinguishing agent under heating conditions, dry, and cool to room temperature to obtain the class D dry powder fire extinguishing agent.

[0017] Further, in the step of preparing the alcohol dispersion of the inorganic non-metallic powder, the dispersant is polyether polyol, and the polyether polyol accounts for 5% by mass of the inorganic non-metallic powder.

[0018] Further, in the step of preparing the saturated sodium chloride aqueous solution with a pH of 1, add concentrated hydrochloric acid to adjust the pH of the saturated sodium chloride aqueous solution to 1.

[0019] Further, in the step of preparing the saturated sodium chloride aqueous solution with a pH of 1, prepare the saturated sodium chloride aqueous solution under the condition of heating to 50°C.

[0020] Further, in the step of preparing the inorganic non-metallic powder-coated sodium chloride particles, the drying condition of the filter residue is: drying at 120°C for 6 h.

[0021] Further, in the step of preparing the dry powder fire extinguishing agent, mix the A and magnesium stearate accounting for 1-5% by weight of the class D dry powder fire extinguishing agent, and heat to 50°C; spray silicone oil accounting for 1-4% by weight of the class D dry powder fire extinguishing agent, and mix; then add molybdenum disulfide accounting for 3-5% by weight of the class D dry powder fire extinguishing agent, and mix; dry at 50°C; cool to obtain the class D dry powder fire extinguishing agent.

[0022] Further, in the preparation method of the inorganic non-metallic powder, the melting temperature is 1300°C, the drying temperature is 50°C, and after ball milling, screening is carried out using a 4000-mesh sieve to obtain the inorganic non-metallic powder.

[0023] On the other hand, provide the application of the aforementioned class D dry powder fire extinguishing agent or the class D dry powder fire extinguishing agent prepared by the aforementioned method in the preparation of a fire extinguishing agent for dealing with magnesium metal or magnesium alloy fires.

[0024] Advantages of the present invention:

[0025] 1. The anti-solvent method is used to prepare inorganic non-metallic powder-coated sodium chloride particles, effectively improving the powder fluidity of the class D dry powder fire extinguishing agent.

[0026] 2. The present invention creatively uses silicon dioxide, boron trioxide and lead oxide to prepare inorganic non-metallic powder. Compared with silicon dioxide alone, the melting point of the inorganic non-metallic powder (below 600 °C) is significantly reduced, which is beneficial to the rapid melting of Class D dry powder extinguishing agent during the fire extinguishing process. Moreover, the viscosity of the molten state of the inorganic non-metallic powder (about 108 mPa·s) is significantly increased compared with the viscosity of the molten state of sodium chloride (about 1.4 mPa·s), which can effectively increase the viscosity of the Class D dry powder extinguishing agent and improve the density and hardness of the outer shell formed after the interaction with combustibles during the fire extinguishing process, thereby improving the wall-attaching effect of the Class D dry powder extinguishing agent to better cope with the wall surface at a certain angle to the horizontal plane, especially the magnesium fire on the vertical wall surface.

[0027] 3. The fire extinguishing principle of the Class D dry powder extinguishing agent of the present invention is as follows: During the fire extinguishing process, when the Class D dry powder extinguishing agent containing the structure of inorganic non-metallic powder-coated sodium chloride particles contacts the surface of the combustible, the inorganic non-metallic powder located on the outer layer of sodium chloride can quickly soften due to its lower melting point than that of silicon dioxide alone. Due to its higher viscosity after melting, it can quickly wrap sodium chloride and adhere to the surface of the combustible to form a denser outer shell. The outer shell will quickly form a hard shell due to the decrease in temperature, blocking the oxygen supply on the surface of the combustible to inhibit combustion. Due to the high density and hardness of the hard shell, it can better prevent the molten magnesium from breaking through the hard shell and contacting oxygen to burn after reaching the boiling point, thereby improving the fire extinguishing effect and reducing the usage amount of the Class D dry powder extinguishing agent. On the other hand, sodium chloride and inorganic non-metallic powder will also absorb a large amount of heat due to phase change during the above process, which is beneficial to the cooling of the combustible to enhance the fire extinguishing effect.

[0028] 4. For the wall surface at a certain angle to the horizontal plane, especially the magnesium fire on the vertical wall surface, the present invention overcomes the disadvantage of the poor wall-attaching effect of the traditional Class D dry powder extinguishing agent and can achieve the rapid control of the magnesium fire on the vertical wall surface.

[0029] 5. The Class D dry powder extinguishing agent of the present invention has excellent anti-caking property, water repellency, fluidity, high and low temperature resistance and corrosion resistance. It is not easy to absorb moisture, has good fluidity, can be stored for a long time, can be used for fire extinguishing by pneumatic conveying, and is relatively flexible to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of the cube steel plate in Example 7 of the present invention;

[0031] Figure 2 It is a picture of the appearance of the magnesium strip after the fire extinguishing of the Class D dry powder extinguishing agent prepared in Example 2 of Example 8;

[0032] Figure 3 It is a picture of the appearance of the magnesium strip after the fire extinguishing of the traditional Class D dry powder extinguishing agent in Example 8;

[0033] Figure 4 Photograph of the wall-attaching effect of the Class D dry powder fire extinguishing agent prepared in Example 2 of Example 8

[0034] Figure 5 Photograph of the wall-attaching effect of the traditional Class D dry powder fire extinguishing agent in Example 8 Detailed implementation manners

[0035] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments.

[0036] During the research process of the present invention, the inventors found that: the wall-attaching effect of the Class D dry powder fire extinguishing agent is related to factors such as the viscosity and melting point of the Class D dry powder fire extinguishing agent after melting, and the compactness and hardness of the outer shell formed after acting with the combustible during the fire extinguishing process.

[0037] Based on this Technical concept of the present invention It lies in: First, mix 19-25% by weight of silicon dioxide, 18-22% of boron trioxide, and 57-63% of lead oxide, melt and mix evenly, water quench, dry and ball mill to obtain an inorganic non-metallic powder. By adding the aforementioned inorganic non-metallic powder as a component to the Class D dry powder fire extinguishing agent through the anti-solvent method, and utilizing the interaction between silicon dioxide, boron trioxide, lead oxide, and sodium chloride, an inorganic non-metallic powder B-coated sodium chloride particle structure is formed, which can simultaneously achieve the following performances: on the one hand, improve the powder fluidity of the Class D dry powder fire extinguishing agent; on the other hand, increase the viscosity of the Class D dry powder fire extinguishing agent after melting, significantly reduce the melting point of the Class D dry powder fire extinguishing agent, improve the compactness and hardness of the outer shell formed after acting with the combustible during the fire extinguishing process, thereby improving the wall-attaching effect of the Class D dry powder fire extinguishing agent to better cope with the wall surface at a certain angle with the horizontal plane, especially the magnesium fire on the vertical wall surface.

[0038] The fire extinguishing principle of the Class D dry powder fire extinguishing agent of the present invention is as follows: During the fire extinguishing process, when the Class D dry powder fire extinguishing agent containing the inorganic non-metallic powder B-coated sodium chloride particle structure contacts the surface of the combustible, the inorganic non-metallic powder B located on the outer layer of sodium chloride can quickly soften due to its lower melting point than that of silicon dioxide alone. Due to its higher viscosity after melting (for example, 108 mPa·s), it can quickly wrap sodium chloride and adhere to the surface of the combustible to form a dense outer shell. The outer shell will quickly form a hard shell due to the decrease in temperature, blocking the oxygen supply on the surface of the combustible to inhibit combustion. Due to the higher compactness and hardness of the hard shell, it can better prevent the molten magnesium from breaking through the hard shell and contacting oxygen to burn after reaching the boiling point, thereby improving the fire extinguishing effect and reducing the usage amount of the Class D dry powder fire extinguishing agent.

[0039] Example 1

[0040] A method for preparing an inorganic non-metallic powder, comprising the following steps: mixing 20% by weight of silicon dioxide, 20% by weight of boron trioxide and 60% by weight of lead oxide, melting and mixing uniformly, quenching with water, drying and ball milling to obtain the inorganic non-metallic powder. Specific parameters are as follows for example:

[0041] The melting step is carried out in a frit furnace at a melting temperature of 1300 °C;

[0042] The drying step is carried out in an oven under the drying conditions of: drying at 50 °C for 2 h;

[0043] The ball milling time is 12 h; after the ball milling step, screening is carried out through a 4000-mesh sieve to obtain the inorganic non-metallic powder B.

[0044] After testing, the melting point of the inorganic non-metallic powder B prepared in Example 1 is below 600 °C, and the viscosity after melting is about 108 mPa·s.

[0045] Example 2

[0046] A method for preparing a Class D dry powder fire extinguishing agent, comprising the following steps:

[0047] (1) Prepare a saturated sodium chloride aqueous solution with a pH of 1 : Prepare a saturated sodium chloride aqueous solution with 58% by weight of sodium chloride in the Class D dry powder fire extinguishing agent under heating conditions, add an acid to adjust the pH of the saturated sodium chloride aqueous solution to 1, and after cooling to room temperature, obtain a saturated sodium chloride aqueous solution with a pH of 1; the acid is, for example, concentrated hydrochloric acid, and the concentration of the concentrated hydrochloric acid can be 37%; the heating temperature is, for example, 50 °C;

[0048] (2) Prepare an alcohol dispersion of inorganic non-metallic powder : Mix 30% by weight of the inorganic non-metallic powder B prepared in Example 1, absolute ethanol and a dispersant in the Class D dry powder fire extinguishing agent, and perform ultrasonic oscillation to uniformly disperse the inorganic non-metallic powder B in the absolute ethanol to obtain an alcohol dispersion of the inorganic non-metallic powder B; the dispersant is, for example, polyether polyol, and the mass percentage of the polyether polyol in the inorganic non-metallic powder B is 5%;

[0049] (3) Prepare inorganic non-metallic powder-coated sodium chloride particles : Rapidly drop the saturated sodium chloride aqueous solution with a pH of 1 prepared in step (1) into the alcohol dispersion of the inorganic non-metallic powder B prepared in step (2), and perform vacuum filtration; dry the obtained filter residue to obtain sodium chloride particles coated with the inorganic non-metallic powder B, denoted as A; the drying conditions of the filter residue are, for example: drying at 120 °C for 6 h;

[0050] (4) Prepare dry powder fire extinguishing agent: Mix the inorganic non-metallic powder B (i.e., A) prepared in step (3) with sodium chloride particles and magnesium stearate accounting for 3% by weight of the Class D dry powder fire extinguishing agent, and heat to 50 °C; spray silicone oil accounting for 4% by weight of the Class D dry powder fire extinguishing agent and mix well; then add molybdenum disulfide accounting for 5% by weight of the Class D dry powder fire extinguishing agent and mix well; dry at 50 °C for 2 h; after cooling, obtain the Class D dry powder fire extinguishing agent.

[0051] Example 3

[0052] A preparation method of a Class D dry powder fire extinguishing agent, referring to Example 2, the difference is only that:

[0053] Sodium chloride in step (1) accounts for 60% by weight of the Class D dry powder fire extinguishing agent;

[0054] The inorganic non-metallic powder B prepared in Example 1 in step (2) accounts for 31% by weight of the Class D dry powder fire extinguishing agent;

[0055] Silicone oil in step (4) accounts for 2% by weight of the Class D dry powder fire extinguishing agent, and molybdenum disulfide accounts for 4% by weight of the Class D dry powder fire extinguishing agent.

[0056] Example 4

[0057] A preparation method of a Class D dry powder fire extinguishing agent, referring to Example 2, the difference is only that:

[0058] Sodium chloride in step (1) accounts for 63% by weight of the Class D dry powder fire extinguishing agent;

[0059] The inorganic non-metallic powder B prepared in Example 1 in step (2) accounts for 32% by weight of the Class D dry powder fire extinguishing agent;

[0060] Magnesium stearate in step (4) accounts for 1% by weight of the Class D dry powder fire extinguishing agent, silicone oil accounts for 1% by weight of the Class D dry powder fire extinguishing agent; molybdenum disulfide accounts for 3% by weight of the Class D dry powder fire extinguishing agent.

[0061] Example 5

[0062] A preparation method of a Class D dry powder fire extinguishing agent, referring to Example 2, the difference is only that:

[0063] The inorganic non-metallic powder B prepared in Example 1 in step (2) accounts for 35% by weight of the Class D dry powder fire extinguishing agent;

[0064] Magnesium stearate in step (4) accounts for 2% by weight of the Class D dry powder fire extinguishing agent, silicone oil accounts for 2% by weight of the Class D dry powder fire extinguishing agent; molybdenum disulfide accounts for 3% by weight of the Class D dry powder fire extinguishing agent.

[0065] Performance Test 1 of Class D Dry Powder Fire Extinguishing Agent in Example 6

[0066] According to the method of the industry standard GA979—2012 "Class D Dry Powder Fire Extinguishing Agent", the water content, anti-caking property, water repellency, fluidity, high and low temperature resistance, and corrosion resistance of the Class D dry powder fire extinguishing agents prepared in Examples 2 to 5 were tested respectively. The results are shown in Table 1.

[0067] Table 1 Partial Performance Test Results of Class D Dry Powder Fire Extinguishing Agents Prepared in Examples 2 to 5

[0068]

[0069] As can be seen from Table 1, the anti-caking property, water repellency, fluidity, high and low temperature resistance, and corrosion resistance of the Class D dry powder fire extinguishing agents prepared in Examples 2 to 5 all meet the technical requirements in the industry standard GA979—2012 "Class D Dry Powder Fire Extinguishing Agent". In particular, the Class D dry powder fire extinguishing agents prepared in Examples 2 to 5 perform excellently in terms of anti-caking property, fluidity, and high and low temperature resistance: the anti-caking property is 17.0 - 19.5 mm, the fluidity is 4.5 - 5.7 s, and the high and low temperature resistance is 3.0 - 3.4 s.

[0070] The Class D dry powder fire extinguishing agents prepared in Examples 2 to 5 can be stored for at least 4 years without deterioration in a well-ventilated, cool, and dry storage environment.

[0071] Example 7 - Fire Extinguishing Performance of Class D Dry Powder Fire Extinguishing Agent - Standard Magnesium Fire Extinguishing Test

[0072] Fire extinguishing experiments were carried out according to the standard GA979—2012 "Class D Dry Powder Fire Extinguishing Agent", where:

[0073] It was carried out in a site where the wind speed was not greater than 3 m / s and there was no rain or snow. A cube steel plate with side length L of 600 ± 10 mm, height H of 300 ± 5 mm, and wall thickness d of 2.5 - 3.0 mm (as Figure 1 shown) was placed on the horizontal ground. Magnesium shavings were added to the square steel plate according to the provisions of item b) in 6.10.1.1 of the standard GA979—2012, and the magnesium shavings were evenly distributed in the steel plate. 14 kg of the Class D dry powder fire extinguishing agent prepared in Examples 2 to 5 was loaded into a wheeled dry powder fire extinguisher and pressurized to 1.2 MPa. A lighting rod was used to ignite the magnesium shavings at the center position of the steel plate, and the ignition was completed within 30 s. When the combustion reached the surface of all the magnesium shavings, the aforementioned wheeled dry powder fire extinguisher was used to extinguish the fire.

[0074] The experimental results showed that the spraying times required for the Class D dry powder fire extinguishing agents prepared in Examples 2 to 5 to successfully extinguish the fire were 160 s, 154 s, 145 s, and 130 s in sequence, and after the spraying was completed, the steel plate could be kept static for 60 min without reignition.

[0075] Example 8 - Comparison of Fire Extinguishing Effects between the Class D Dry Chemical Fire Extinguishing Agent of the Present Invention and Traditional Class D Dry Chemical Fire Extinguishing Agents

[0076] 1. Compactness and Hardness of the Formed Outer Shell

[0077] The fire extinguishing experiment was carried out using the method of Example 7, with the difference being that magnesium ribbon was used instead of magnesium chips as the fuel for the experiment. Among them, the thickness of the magnesium ribbon was 0.25 mm, and the amount of magnesium ribbon used was 20 g. 100 g of the Class D dry chemical fire extinguishing agent prepared in Example 2 and traditional Class D dry chemical fire extinguishing agents (for their formula and preparation method, refer to the Chinese invention application with the publication number CN104069610A) were respectively loaded into the vibrating screen. A magnesium ribbon was ignited at the center position of the steel plate using an ignition rod, and the ignition was completed within 30 s. When the combustion proceeded for 20 s, the vibrating screen was started, and the fire extinguishing agent fell from the screen mesh for fire extinguishing.

[0078] The experimental results showed that the fire extinguishing time of the Class D dry chemical fire extinguishing agent prepared in Example 2 was 20 s, and there was no reignition after standing for 60 min. While the fire extinguishing time of the traditional Class D dry chemical fire extinguishing agent was 35 s. Figure 2 and Figure 3 are respectively the appearance pictures of the magnesium ribbon after fire extinguishing with the Class D dry chemical fire extinguishing agent prepared in Example 2 and the traditional Class D dry chemical fire extinguishing agent. It can be seen from Figure 2 and Figure 3 that after fire extinguishing with the Class D dry chemical fire extinguishing agent of the present invention, a vitreous hard shell covered the surface of the magnesium ribbon. This hard shell tightly adhered to the surface of the magnesium ribbon. The maximum thickness of this hard shell was close to 5 mm, and the Mohs hardness was about 5.5. While after fire extinguishing with the traditional Class D dry chemical fire extinguishing agent, only a thin outer shell (with a maximum thickness less than 2 mm) was formed on the surface of the magnesium ribbon, and the texture of this outer shell was brittle, with a Mohs hardness of only 3.5.

[0079] 2. Wall Attachment Effect

[0080] Test method: The magnesium metal component was placed vertically, heated with a spray gun for 5 min, and then 10 g of the Class D dry chemical fire extinguishing agent prepared in the present invention (Examples 2 - 5) and traditional Class D dry chemical fire extinguishing agents (for their formula and preparation method, refer to the Chinese invention application with the publication number CN104069610A) were sprayed on its surface. After 5 min, the wall attachment effects of the two were compared.

[0081] The experimental results are as shown in Figure 4 and Figure 5 that the wall attachment effect of the Class D dry chemical fire extinguishing agent of the present invention is significantly improved compared with the traditional Class D dry chemical fire extinguishing agent: the successful attachment rate of the Class D dry chemical fire extinguishing agent of the present invention after 5 min is 5% - 10%, while the successful attachment rate of the traditional Class D dry chemical fire extinguishing agent after 5 min is less than 2%.

[0082] Example 9

[0083] Application of the Class D dry powder fire extinguishing agent prepared in Examples 2 to 5 in the preparation of a fire extinguishing agent for magnesium metal or magnesium alloy fires.

[0084] According to the foregoing performance test results, the water content, anti-caking property, water repellency, fluidity, high and low temperature resistance, and corrosion resistance of the fire extinguishing agent for magnesium metal or magnesium alloy fires prepared based on the Class D dry powder fire extinguishing agent prepared in Examples 2 to 5 are excellent. At the same time, a shell with relatively high density and hardness can be formed during the fire extinguishing process. For the wall surface at a certain angle to the horizontal plane, especially the vertical wall surface, the wall attachment performance is excellent, and the magnesium metal or magnesium alloy fire on the vertical wall surface can be quickly extinguished.

Claims

1. A class D dry powder fire extinguishing agent, characterized in that, Comprising the following components by weight percentage: Sodium chloride 58 - 63%; Inorganic non - metallic powder 25 - 35%; Glidant 4 - 10%; Moisture - proof agent 1 - 4%; Wherein, the inorganic non - metallic powder coats the outer layer of sodium chloride particles; the preparation method of the inorganic non - metallic powder includes: mixing silicon dioxide with a weight percentage of 19 - 25%, boron trioxide with a weight percentage of 18 - 22%, and lead oxide with a weight percentage of 57 - 63%, melting and mixing evenly at 1300 °C, water quenching, drying and ball - milling to obtain the inorganic non - metallic powder.

2. The Class D dry powder fire extinguishing agent according to claim 1, wherein The weight percentage of the inorganic non - metallic powder is 30 - 32%.

3. The Class D dry powder fire extinguishing agent according to claim 1, wherein The inorganic non - metallic powder, by weight percentage, comprises the following components: silicon dioxide 20%, boron trioxide 20%, and lead oxide 60%.

4. The Class D dry powder fire extinguishing agent according to claim 1, characterized in that, The glidant includes at least one of molybdenum disulfide, magnesium stearate, talc powder, silica white, or boron nitride.

5. The Class D dry powder fire extinguishing agent according to claim 1 or 4, characterized in that, The glidant, by weight percentage of the Class D dry powder fire extinguishing agent, comprises the following components: molybdenum disulfide 3 - 5% and magnesium stearate 1 - 5%.

6. The Class D dry powder fire extinguishing agent according to claim 1, wherein The moisture - proof agent includes silicone oil.

7. A preparation method of a class D dry powder fire extinguishing agent, characterized in that, Including the following steps: Preparing a saturated sodium chloride aqueous solution with a pH of 1: configuring sodium chloride with a weight percentage of 58 - 63% of the Class D dry powder fire extinguishing agent into a saturated sodium chloride aqueous solution under heating conditions, adding acid to adjust the pH of the saturated sodium chloride aqueous solution to 1, and after cooling, obtaining a saturated sodium chloride aqueous solution with a pH of 1; Preparing an alcohol dispersion of the inorganic non - metallic powder: mixing the inorganic non - metallic powder with a weight percentage of 25 - 35% of the Class D dry powder fire extinguishing agent, absolute ethanol, and a dispersant, and ultrasonically oscillating to uniformly disperse the inorganic non - metallic powder in absolute ethanol to obtain an alcohol dispersion of the inorganic non - metallic powder; wherein, the preparation method of the inorganic non - metallic powder includes: mixing silicon dioxide with a weight percentage of 19 - 25%, boron trioxide with a weight percentage of 18 - 22%, and lead oxide with a weight percentage of 57 - 63%, melting and mixing evenly at 1300 °C, water quenching, drying and ball - milling to obtain the inorganic non - metallic powder; Preparing inorganic non - metallic powder - coated sodium chloride particles: quickly dropping the saturated sodium chloride aqueous solution with a pH of 1 into the alcohol dispersion of the inorganic non - metallic powder, and performing vacuum filtration; drying the obtained filter residue to obtain inorganic non - metallic powder - coated sodium chloride particles, denoted as A; Preparing the dry powder fire extinguishing agent: mixing the A, the glidant with a weight percentage of 4 - 10% of the Class D dry powder fire extinguishing agent, and the moisture - proof agent with a weight percentage of 1 - 4% of the Class D dry powder fire extinguishing agent under heating conditions, drying, and after cooling, obtaining the Class D dry powder fire extinguishing agent.

8. The preparation method of the Class D dry powder fire extinguishing agent according to claim 7, characterized in that, In the step of preparing the alcohol dispersion of the inorganic non - metallic powder, the dispersant is polyether polyol, and the polyether polyol accounts for 5% of the mass of the inorganic non - metallic powder.

9. The preparation method of the Class D dry powder fire extinguishing agent according to claim 7, wherein In the preparation method of the inorganic non - metallic powder, the melting temperature is 1300 °C, the drying temperature is 50 °C, and after ball - milling, screening is carried out using a 4000 - mesh sieve to obtain the inorganic non - metallic powder.

10. Use of a Class D dry powder fire extinguishing agent according to any one of claims 1-6 or a Class D dry powder fire extinguishing agent prepared by the method for preparing a Class D dry powder fire extinguishing agent according to any one of claims 7-9 in the preparation of a fire extinguishing agent for dealing with magnesium metal or magnesium alloy fires.

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