Composite explosion suppressant and preparation method thereof

Abstract

The invention relates to the technical field of dust explosion prevention and control, in particular to a composite explosion suppressant and a preparation method thereof. The composite explosion suppressant comprises the following components in percentage by mass: 40-60% of silicate mineral powder, 20-35% of a phosphate explosion suppressant and 15-25% of biomass charcoal. Physical inerting of the silicate mineral powder, chemical inhibition of the phosphate explosion suppressant and surface adsorption of the biomass charcoal cooperate to form a protection system covering the whole explosion process, and the overall explosion suppression efficiency is remarkably improved. The silicate powder can form a compact coating layer on the surface of the dust, so that oxygen is isolated, and flame propagation is hindered; the phosphate is heated and decomposed to release inert gas, formation of a stable carbon layer is promoted, and free radical chain reaction is terminated; biomass charcoal adsorbs combustible gas and free radicals by virtue of developed pores, and cooperates with phosphate to enhance the stability of a charcoal layer, so that complementation and synergism at different explosion suppression stages are realized.

Description

Technical Field

[0001] This invention relates to the field of dust explosion prevention technology, and in particular to a composite explosion suppressant and its preparation method. Background Technology

[0002] Grain dust (such as wheat flour and corn starch) is highly susceptible to forming explosive dust clouds during processing, transportation, and storage, which can easily trigger serious explosions when exposed to open flames or high temperatures. To mitigate such risks, current technologies often employ the addition of inert explosion-suppressing powders to the dust environment. Common types include: chemical explosion suppressants, such as sodium bicarbonate, which decompose upon heating to produce inert gases; phosphate explosion suppressants, such as ammonium polyphosphate, which combine chemical free radical termination and physical inertization; and silicate mineral powders, such as diatomaceous earth and montmorillonite, which primarily function through physical oxygen isolation and cooling.

[0003] However, the aforementioned single or simply compounded explosion suppressants still have limitations in practical applications. Sodium bicarbonate acts rapidly but lacks sustained effect, and its effective suppression concentration is relatively high; silicate mineral powders have limited chemical suppression efficacy and often require large additions; while some highly efficient phosphates present a trade-off between cost and environmental friendliness. More importantly, there is often a lack of effective synergistic mechanisms among various explosion suppressing components, making it difficult to further improve the overall explosion suppression efficiency, and the total amount required to reach the safety threshold is large, which may affect the subsequent utilization of the protected material or increase the environmental burden.

[0004] Therefore, developing a composite explosion suppressant based on a clear synergistic mechanism that can achieve efficient explosion suppression, is environmentally friendly, and is easy to produce and use on a large scale is of great practical significance for improving the dust explosion protection level in the grain industry. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a composite explosion suppressant and its preparation method. Through the synergistic effect of silicate mineral powder, phosphate explosion suppressant and biochar, multi-level and multi-mechanism suppression of dust explosions is achieved.

[0006] To achieve the above objectives, the present invention provides a composite explosion suppressant comprising the following components by mass fraction: 40-60% silicate mineral powder, 20-35% phosphate explosion suppressant, and 15-25% biochar.

[0007] Preferably, the silicate mineral powder is selected from at least one of diatomaceous earth, bentonite, illite, and pyrophyllite; the specific surface area of ​​the silicate mineral powder is ≥20 m². 2 / g, particle size D50≤10μm.

[0008] Preferably, the phosphate-based explosion suppressant is selected from at least one of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0009] Preferably, the biochar is produced by pyrolysis of agricultural waste under an inert atmosphere, wherein the inert atmosphere is selected from nitrogen or argon, and the pyrolysis temperature is 400-600℃.

[0010] Preferably, the specific surface area of ​​biochar is ≥200m². 2 / g, with a pore size of 2-50nm.

[0011] Preferably, it also includes a surfactant, wherein the mass fraction of the surfactant in the composite explosion suppressant is 0.5-3%.

[0012] Preferably, the surfactant is selected from at least one of sodium polyacrylate and sodium dodecyl sulfate.

[0013] The present invention also provides a method for preparing the aforementioned composite anti-knock agent, comprising the following steps: The components are mixed and then crushed and sieved in sequence to obtain a composite explosion suppressant.

[0014] Preferably, the mixing speed is 200-500 r / min and the mixing time is 10-30 min.

[0015] The present invention also provides a method for suppressing grain dust explosions by adding the aforementioned composite explosion suppressant to the grain dust.

[0016] The beneficial effects of this invention are as follows: 1. This invention provides a composite explosion suppressant, comprising the following components by mass fraction: 40-60% silicate mineral powder, 20-35% phosphate-based explosion suppressant, and 15-25% biochar. This invention achieves a comprehensive protection system covering the entire explosion process through the synergistic effect of physical inerting by silicate mineral powder, chemical inhibition by phosphate-based explosion suppressant, and surface adsorption by biochar, significantly improving overall explosion suppression efficiency. Silicate powder forms a dense coating layer on the dust surface, isolating oxygen and hindering flame propagation; phosphate decomposes upon heating, releasing inert gases, promoting the formation of a stable char layer, and terminating free radical chain reactions; biochar, with its well-developed pores, adsorbs combustible gases and free radicals, and synergistically enhances the stability of the char layer with phosphate, achieving complementarity and synergistic effect at different explosion suppression stages.

[0017] 2. The biochar used is derived from agricultural waste such as corn stalks and rice husks. Controlled pyrolysis enables high-value utilization of waste, reducing reliance on non-renewable resources. The overall formula is environmentally friendly, suitable for explosion suppression protection of sensitive materials such as grains, and meets green and safe production requirements.

[0018] 3. By optimizing the component mass fraction, the system balances explosion suppression performance with cost and ease of addition. This system is particularly suitable for typical grain dusts such as wheat flour and corn starch, and can also be extended to other locations with organic dust explosion hazards, demonstrating good versatility.

[0019] 4. The preparation method involves only conventional steps such as raw material drying, mechanical mixing, pulverization and sieving. The process conditions are mild, and no complex equipment or harsh reaction environment is required. It is suitable for large-scale continuous production and has strong economic efficiency and operational feasibility.

[0020] 5. Due to the synergistic effect between components, it can achieve efficient explosion suppression at a low addition ratio, which helps to reduce the impact on the physicochemical properties of the protected object, while reducing storage and handling costs, and has good application prospects.

[0021] In summary, this invention constructs a synergistic explosion suppression system by innovatively combining three components. It has significant advantages in terms of the integrity of the explosion suppression mechanism, environmental friendliness, process feasibility, and economy, providing a highly efficient, green, and practical new material solution for dust explosion prevention. Detailed Implementation

[0022] This invention provides a composite explosion suppressant, comprising the following components by mass fraction: 40-60% silicate mineral powder, 20-35% phosphate explosion suppressant, and 15-25% biochar.

[0023] In this invention, the silicate mineral powder is selected from at least one of diatomaceous earth, bentonite, illite, and pyrophyllite; the specific surface area of ​​the silicate mineral powder is ≥20 m². 2 / g, particle size D50≤10μm.

[0024] In this invention, the phosphate-based explosion suppressant is selected from at least one of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

[0025] In this invention, the degree of polymerization of ammonium polyphosphate is 20-1000.

[0026] In this invention, biochar is obtained by pyrolyzing agricultural waste under an inert atmosphere, the inert atmosphere being selected from nitrogen or argon, and the pyrolysis temperature is 400-600℃.

[0027] In this invention, agricultural waste is selected from corn stalks or rice husks.

[0028] In this invention, the specific surface area of ​​the biochar is ≥200m². 2 / g, with a pore size of 2-50nm.

[0029] The present invention also includes a surfactant, wherein the mass fraction of the surfactant in the composite explosion suppressant is 0.5-3%.

[0030] In this invention, the surfactant is selected from at least one of sodium polyacrylate and sodium dodecyl sulfate.

[0031] The present invention also provides a method for preparing the aforementioned composite anti-knock agent, comprising the following steps: The components are mixed and then crushed and sieved in sequence to obtain a composite explosion suppressant.

[0032] In this invention, before mixing the components, the silicate mineral powder, phosphate explosion suppressant, and biochar are dried at 50-80°C until the water content is ≤2%.

[0033] Taking silicate mineral powder as an example, it is dried at 50-80℃ until the mass fraction of water in the silicate mineral powder is ≤2%.

[0034] In this invention, the mixing speed is 200-500 r / min and the mixing time is 10-30 min.

[0035] In this invention, the material passing through a 500-700 mesh sieve and collecting the undersize material is the composite explosion suppressant.

[0036] The present invention also provides a method for suppressing grain dust explosions by adding the aforementioned composite explosion suppressant to the grain dust.

[0037] In this invention, the grain dust is selected from at least one of wheat flour, corn starch, soybean flour, and rice flour.

[0038] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0039] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0040] Example 1 This embodiment provides a composite explosion suppressant, comprising the following components by mass fraction: The composition consists of 50% silicate mineral powder, 30% phosphate explosion suppressant, 18% biochar, and 2% surfactant. The silicate mineral powder is diatomaceous earth (specific surface area of ​​80 m²).2 / g, D50=8μm); phosphate-based explosion suppressant is ammonium polyphosphate (degree of polymerization 500); biochar (specific surface area 350m²). 2 / g (pore size 2-50nm) was prepared by pyrolysis of corn stalks at 500℃ under nitrogen atmosphere; the surfactant was sodium dodecyl sulfate.

[0041] This embodiment also provides a method for preparing the above-mentioned composite explosion suppressant, including the following steps: The silicate mineral powder, phosphate-based explosion suppressant, and biochar were dried at 65°C to a water content of 1%. Then, the above components (silicate mineral powder, phosphate-based explosion suppressant, biochar, and surfactant) were mixed at 300 r / min for 20 min, pulverized sequentially, passed through a 600-mesh sieve, and the sieve-underfill material was collected to obtain the composite explosion suppressant.

[0042] Example 2 This embodiment provides a composite explosion suppressant, which differs from Embodiment 1 in that the mass fraction of each component is adjusted as follows: silicate mineral powder 55%, phosphate explosion suppressant 25%, biochar 18%, and surfactant 2%.

[0043] This embodiment also provides a method for preparing the above-mentioned composite explosion suppressant, which is the same as in Example 1.

[0044] Example 3 This embodiment provides a composite explosion suppressant, which differs from Embodiment 1 in that the mass fraction of each component is adjusted as follows: silicate mineral powder 45%, phosphate explosion suppressant 30%, biochar 23%, and surfactant 2%.

[0045] This embodiment also provides a method for preparing the above-mentioned composite explosion suppressant, which is the same as in Example 1.

[0046] Comparative Example 1 This comparative example provides a detonator that differs from Example 1 in that the mass fractions of each component are adjusted as follows: silicate mineral powder 100%, phosphate detonator 0%, biochar 0%, and surfactant 0%.

[0047] This comparative example also provides a method for preparing the above-mentioned anti-knock agent, including the following steps: The silicate mineral powder was dried at 65°C to a water content of 1%, then pulverized and passed through a 600-mesh sieve. The material passing through the sieve was collected to obtain the explosion suppressant.

[0048] Comparative Example 2 This comparative example provides a detonator that differs from Example 1 in that the mass fractions of each component are adjusted as follows: silicate mineral powder 0%, phosphate detonator 100%, biochar 0%, and surfactant 0%.

[0049] This comparative example also provides a method for preparing the above-mentioned anti-knock agent, including the following steps: The phosphate-based explosion suppressant was dried at 65°C to a water content of 1%, then pulverized sequentially, passed through a 600-mesh sieve, and the sieve-underfill material was collected to obtain the explosion suppressant.

[0050] Comparative Example 3 This comparative example provides a detonator that differs from Example 1 in that the mass fractions of each component are adjusted as follows: silicate mineral powder 68%, phosphate detonator 30%, biochar 0%, and surfactant 2%.

[0051] This comparative example also provides a method for preparing the above-mentioned anti-knock agent, including the following steps: The silicate mineral powder and phosphate-based explosion suppressant were dried at 65°C to a water content of 1%. Then, the above components (silicate mineral powder, phosphate-based explosion suppressant and surfactant) were mixed at 300 r / min for 20 min, pulverized sequentially, passed through a 600-mesh sieve, and the sieve-underfill material was collected to obtain the explosion suppressant.

[0052] Experimental Example 1 The explosion suppression performance of the composite explosion suppressants in Examples 1-3 and the explosion suppressants in Comparative Examples 1-3 was tested, and the test results are recorded in Table 1. The specific test procedures and conditions are as follows: (1) Test dust: Select representative explosive grain dust - wheat flour; its particle size distribution is D50=75μm, volatile content ≥85%, which is a typical flammable and explosive dust.

[0053] (2) Testing equipment: A standard 20L spherical explosion test device is used, equipped with a high-precision pressure sensor, data acquisition system, chemical ignition head (ignition energy: 10kJ) and dust dispersion pneumatic system.

[0054] (3) Test method: The test was conducted in accordance with the national standard GB / T16426-1996, "Determination of Maximum Explosion Pressure and Maximum Pressure Rise Rate of Dust Clouds". A certain mass of wheat flour and the explosion suppressant to be tested were pre-mixed evenly in a dry environment to form a "dust-explosion suppressant" mixture system. A sample of this mixture system (total mass fixed at 5.0 g) was weighed and placed in the dust storage tank of the device. Compressed air at 0.1 MPa (absolute pressure) was introduced into the explosion chamber as a dispersion medium. Through program control, the dust spray valve was first opened, so that the dust was evenly sprayed into the center of the 20L spherical container within 60 ms to form a dust cloud. After a delay of 60 ms, the chemical ignition head was triggered for ignition. The pressure-time curve during the explosion process was recorded by a pressure sensor.

[0055] (4) Key test parameters: The dust concentration was fixed at the mass concentration of wheat dust itself, 500 g / m³. 3 (This concentration is close to the most violent explosive concentration of this wheat dust); the proportion of explosion suppressant added is set to 20% (the percentage of the explosion suppressant mass to the total mass of "wheat flour + explosion suppressant"); the ambient temperature is 25℃ and the relative humidity is 35%.

[0056] (5) Evaluation index: Maximum explosion pressure (P) max ): The maximum pressure value (gauge pressure, unit: MPa) measured during the explosion process; the lower the value, the better the explosion suppression effect; maximum pressure rise rate ((dp / dt)). max ): The maximum slope of the rising segment of the explosion pressure curve (unit: MPa / s). This indicator can more sensitively reflect the intensity of the explosion. The lower the value, the more thoroughly the explosion is suppressed.

[0057] Table 1 Test Results

[0058] Therefore, this invention employs the aforementioned composite explosion suppressant, which, through the synergistic effect of physical inerting of silicate mineral powder, chemical inhibition of phosphate-based explosion suppressants, and surface adsorption of biochar, forms a protective system covering the entire explosion process, significantly improving overall explosion suppression efficiency. Silicate powder can form a dense coating layer on the dust surface, isolating oxygen and hindering flame propagation; phosphate decomposes upon heating, releasing inert gases, promoting the formation of a stable char layer, and terminating free radical chain reactions; biochar, with its well-developed pores, adsorbs combustible gases and free radicals, and synergistically enhances the stability of the char layer with phosphate, achieving complementarity and synergistic effect at different explosion suppression stages.

[0059] Finally, it should be noted that the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite anti-knock agent, characterized in that, Components including the following mass fractions: 40-60% silicate mineral powder, 20-35% phosphate explosion suppressant, and 15-25% biochar.

2. The composite explosion suppressant according to claim 1, characterized in that, The silicate mineral powder is selected from at least one of diatomaceous earth, bentonite, illite, and pyrophyllite; the specific surface area of ​​the silicate mineral powder is ≥20 m². 2 / g, particle size D50≤10μm.

3. The composite explosion suppressant according to claim 1, characterized in that, Phosphate-based explosion suppressants are selected from at least one of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

4. The composite explosion suppressant according to claim 1, characterized in that, Biochar is produced by pyrolyzing agricultural waste under an inert atmosphere, which is selected from nitrogen or argon, and the pyrolysis temperature is 400-600℃.

5. The composite explosion suppressant according to claim 4, characterized in that, Biochar with a specific surface area ≥200m² 2 / g, with a pore size of 2-50nm.

6. The composite explosion suppressant according to claim 1, characterized in that, It also includes surfactants, with the mass fraction of surfactants in the composite explosion suppressant being 0.5-3%.

7. The composite explosion suppressant according to claim 6, characterized in that, The surfactant is selected from at least one of sodium polyacrylate and sodium dodecyl sulfate.

8. The method for preparing the composite anti-knock agent according to any one of claims 1-7, characterized in that, Includes the following steps: The components are mixed and then crushed and sieved in sequence to obtain a composite explosion suppressant.

9. The preparation method according to claim 8, characterized in that, The mixing speed is 200-500 r / min, and the time is 10-30 min.

10. A method for suppressing grain dust explosions, characterized in that, Add the composite explosion suppressant according to any one of claims 1-7 to grain dust.

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