Method for preparing superfine explosive based on high-pressure micro-jet technology

Abstract

The invention relates to the technical field of energetic material preparation, in particular to a method for preparing a superfine explosive based on a high-pressure micro-jet technology. Comprising the following steps: (1) preparing explosive particle turbid liquid; (2) high-pressure microjet refining treatment; (3) filtering and drying the superfine explosive; according to the invention, the high-pressure microjet technology is introduced into the refining of the explosive, and explosive particles are crushed and uniformly dispersed by virtue of the effects of shearing, impacting, friction, cavitation and the like generated when the explosive particle suspension passes through the microchannels at a high speed, so that the superfine explosive is prepared. The preparation method disclosed by the invention is simple and reliable, good in repeatability, high in safety and high in heat transfer and mass transfer efficiency, the obtained explosive particles are narrow in particle size distribution, the preparation process is green and environment-friendly, pollutants are not generated, and industrial amplification is easy.

Description

Technical Field

[0001] The invention relates to the technical field of energetic material preparation, and in particular to a method for preparing ultrafine explosives based on high-pressure micro-jet technology. Background Art

[0002] The rapid development of weapon systems has put forward more stringent requirements on the performance of energetic materials, requiring them to meet high energy density and lethality while also having the characteristics of high stability, high safety, and high controllability of energy release. Many properties of energetic materials such as energy release, safety performance, detonation and detonation transmission are not only related to the type of explosives, but also to their particle size, crystal defects, morphology, etc. A large number of studies have shown that when the particle size of energetic materials is reduced, there will be significant changes such as reduced mechanical sensitivity, detonation close to ideal detonation, more complete energy release during explosion, and reduced critical detonation diameter. In order to obtain ultrafine explosive particles, domestic and foreign scholars have developed a variety of methods such as jet crystallization, spray drying, mechanical ball milling, ultrasonic crushing, microfluidics-assisted crystallization, etc., and prepared ultrafine RDX, HMX, FOX-7, PETN, CL-20, HNS explosive particles, and the minimum particle size can reach tens of nanometers. However, the existing technology has problems such as low preparation efficiency and large amount of organic solvents. Therefore, applying some new technologies to the preparation process of ultrafine explosives and developing new methods for ultrafine explosives are still one of the research hotspots in the field of energetic materials.

[0003] High-pressure microfluidics is a new environmentally friendly and advanced high-pressure homogenization technology. It mainly uses high pressure to drive the liquid material through micro-channels of various shapes at high speed. The material is strongly impacted in the impact cavity. Under the effects of shear, impact, friction and cavitation, the various components of the material are broken, and finally the physical modification of the material is achieved. The high-pressure microfluidics technology has the advantages of high heat and mass transfer efficiency and high precision in particle refinement. It has been widely used in many fields such as aerodynamics, organic chemistry, food processing, and pharmaceutical preparations. However, there are few reports on the research on the high-pressure microfluidics technology to refine explosive particles. Summary of the invention

[0004] The present invention overcomes the deficiencies of the prior art and provides a method for preparing ultrafine explosives based on high-pressure microfluidics technology; the high-pressure microfluidics technology is integrated with the ultrafine explosive technology to provide a new idea for the ultrafineness and particle size control of energetic materials.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing ultrafine explosives based on high-pressure microfluidics technology, comprising the following steps: (1) Preparation of explosive particle suspension Adding explosives and liquid medium into a container, inserting an ultrasonic probe into the liquid medium in the container to ultrasonically disperse the explosive particles to prepare an explosive particle suspension; (2) High-pressure microfluidization treatment The suspension is treated by using a high-pressure micro-jet homogenizer: first, a barrel is mounted on the homogenizer, and the explosive particle suspension prepared in step (1) is added into the barrel; then, high-pressure micro-jet process parameters are set; finally, a circulating water cooling device of the homogenizer is turned on, and when the temperature drops to the set temperature, the homogenizer is turned on to perform high-pressure homogenization treatment on the suspension; (3) Filtration and drying of ultrafine explosives The suspension obtained in step (2) is filtered, washed and dried to obtain ultrafine explosive particles.

[0006] The technical principle adopted by the present invention is: in the process of high-pressure micro-jet refinement, the suspension is first withdrawn into the high-pressure cylinder through the plunger rod, and then pressurized and accelerated into the diamond interactive cavity. When the explosive suspension passes through the micro-channel, the flow rate increases rapidly instantly, forming a huge velocity gradient, generating violent extrusion and shearing effects, causing high-speed collisions between particles, and generating strong impact and friction effects. At the same time, there is also a huge pressure drop in the microchannel. When the pressure drops to the saturated vapor pressure of the liquid medium, the liquid medium begins to boil and vaporizes extremely quickly, forming a large number of bubbles. When the suspension leaves the micro-channel, the pressure increases rapidly, causing the bubbles to burst and produce cavitation. Under the synergistic effects of shear, impact, friction and cavitation, the explosive particles can be efficiently crushed.

[0007] Furthermore, the explosive in step (1) is HNS, FOX-7, RDX, HMX, DAAF, TKX-50 and LLM-105; and the liquid medium in step (1) is water, alcohol solvent or a mixture of several thereof.

[0008] As a further limitation of the technical solution of the present invention, the liquid medium in step (1) is one or a mixture of water and alcohol solvents.

[0009] As a further limitation of the technical solution of the present invention, in step (1), the liquid medium should be slightly soluble or difficult to dissolve the explosive particles, and the solubility of the explosive particles in the liquid medium is less than 0.1 g / ml.

[0010] As a further limitation of the technical solution of the present invention, in step (1), the mass ratio of the explosive particles to the liquid medium is 1:5 to 1:60.

[0011] As a further limitation of the technical solution of the present invention, in step (1), the mass ratio of the explosive particles to the liquid medium is 1:10 to 1:20.

[0012] As a further limitation of the technical solution of the present invention, in step (1), the length of the ultrasonic probe is 4-10 mm, the ultrasonic power is 200-300 W, and the ultrasonic treatment time is 5-20 min.

[0013] As a further limitation of the technical solution of the present invention, in step (2), the high-pressure micro-jet process parameters include pressure, number of cycles and circulating water temperature; the high-pressure micro-jet pressure is 35 to 150 MPa, and the number of cycles is 5 to 100 times.

[0014] As a further limitation of the technical solution of the present invention, in step (2), the high-pressure microjet pressure is 100-138 MPa, and the number of cycles is 30 to 70 times.

[0015] As a further limitation of the technical solution of the present invention, the temperature of the circulating water cooling device in step (2) is set to 0-10°C.

[0016] As a further limitation of the technical solution of the present invention, the filtering method in step (3) is vacuum filtration or centrifugal filtration; the drying method is water bath drying, vacuum drying or freeze drying.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention introduces high-pressure microfluidics into the explosive refinement process. When the explosive particle suspension passes through the microchannel at high speed, shearing, impact, friction and cavitation synergistic effects will occur, which helps to enhance the explosive particle crushing effect and improve the refinement efficiency.

[0018] (2) The present invention can prepare ultrafine explosives of different particle sizes by adjusting process parameters such as jet pressure, number of cycles, mass ratio of explosive to liquid medium, and type of liquid medium, thereby realizing the preparation of multi-scale main explosives and further regulating the particle size of ultrafine explosives.

[0019] (3) The present invention only uses water and alcohol solvents as liquid media and uses a small amount of solvent. Compared with crystallization refinement technology, it has the characteristics of low toxicity and green environmental protection.

[0020] (4) The preparation method of the present invention is simple and reliable, has good repeatability, high safety, high heat and mass transfer efficiency, and the obtained explosive particles have a narrow particle size distribution. In addition, the preparation process is green and environmentally friendly, does not generate pollutants, and is easy to scale up industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM photograph of the raw material HNS used in Example 1.

[0022] Figure 2 This is the SEM image of the ultrafine HNS prepared in Example 1.

[0023] Figure 3 This is the particle size distribution diagram of the raw material HNS used in Example 1.

[0024] Figure 4This is the particle size distribution diagram of the ultrafine HNS prepared in Example 1.

[0025] Figure 5 This is the SEM photo of the raw material FOX-7 used in Example 2.

[0026] Figure 6 This is the SEM photograph of the ultrafine FOX-7 prepared in Example 2.

[0027] Figure 7 This is the particle size distribution diagram of the raw material FOX-7 used in Example 2.

[0028] Figure 8 This is the particle size distribution diagram of the ultrafine FOX-7 prepared in Example 2. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific embodiments. Example 1

[0030] A method for preparing ultrafine HNS based on high-pressure microfluidization technology comprises the following steps: ① Preparation of explosive particle suspension: HNS raw material and anhydrous ethanol are measured at a mass ratio of 1:20 and added to a container. The ultrasonic probe is inserted into the liquid medium anhydrous ethanol in the container to ultrasonically disperse the HNS explosive particles. The amplitude is set to 6 mm and the ultrasonic power is set to 230 W. After ultrasonic treatment for 15 minutes, the HNS explosive particle suspension is prepared.

[0031] ② High-pressure micro-jet refinement treatment: First, assemble the barrel at the specified position of the homogenizer, and add the HNS explosive particle suspension into the barrel; secondly, set the jet pressure of the homogenizer to 138Mpa, the number of cycles to 50 times, and the temperature of the circulating water cooling device to 5°C; finally, turn on the circulating water cooling device of the homogenizer, and when the temperature drops to 5°C, turn on the homogenizer to perform 50 times of high-pressure homogenization treatment on the suspension.

[0032] ③ Filtration and drying of ultrafine explosives: The liquid medium ethanol and HNS particles are filtered and separated by vacuum filtration, and then the HNS particles are placed in a freeze-drying oven and dried for 4 hours to obtain ultrafine HNS.

[0033] The structure and morphology of the raw HNS and the ultrafine HNS obtained in the above steps were characterized by field emission scanning electron microscopy (SEM). Figure 1 and Figure 2As shown in the figure, by comparing the two figures, it can be clearly seen that the raw HNS is mostly irregular long flakes with sharp edges and larger particles; the HNS after refinement is mostly short flakes with smooth edges and corners, and the particles are significantly smaller and the distribution range is narrower. The raw HNS and the ultrafine HNS obtained in the above steps were analyzed by laser particle size analyzer, and the particle size distribution is shown in Figure 3 and Figure 4 The particle size distribution of raw HNS is D10=8.141μm, D50=25.71μm, D90=65.12μm; the particle size distribution of HNS after refinement is D10=0.302μm, D50=0.560μm, D90=0.982μm. Example 2

[0034] A method for preparing ultrafine FOX-7 based on high-pressure microfluidics technology comprises the following steps: ① Preparation of explosive particle suspension: FOX-7 raw material and water were measured at a mass ratio of 1:10 and added to a container. The ultrasonic probe was inserted into the liquid medium water in the container to ultrasonically disperse the FOX-7 explosive particles. The amplitude was set to 6 mm and the ultrasonic power was set to 230 W. After ultrasonic treatment for 10 minutes, a FOX-7 explosive particle suspension was prepared.

[0035] ② High-pressure micro-jet refinement treatment: First, assemble the barrel at the specified position of the homogenizer, and add the FOX-7 explosive particle suspension into the barrel; secondly, set the jet pressure of the homogenizer to 120Mpa, the number of cycles to 60 times, and the temperature of the circulating water cooling device to 5°C; finally, turn on the circulating water cooling device of the homogenizer, and when the temperature drops to 5°C, turn on the homogenizer to perform 60 times of high-pressure homogenization treatment on the suspension.

[0036] ③ Filtration and drying of ultrafine explosives: The liquid medium water and FOX-7 particles are filtered and separated by vacuum filtration, and then the FOX-7 particles are placed in a freeze-drying oven and dried for 4 hours to obtain ultrafine FOX-7.

[0037] The structure and morphology of the raw material FOX-7 and the ultrafine FOX-7 obtained in the above steps were characterized by field emission scanning electron microscopy (SEM). Figure 5 and Figure 6 As shown in the figure, it can be clearly seen from the comparison of the two figures that the raw material FOX-7 is mostly cubic flakes and irregular block particles, and a typical layered crystal structure can be observed, with a small amount of pores on the surface and larger particles; the surface of the refined FOX-7 particles is smoother than that of the raw material, the particle size is significantly reduced, and the particle size distribution range is narrowed, and the particle size is more uniform. The laser particle size analyzer is used to analyze the particle size of the raw material FOX-7 and the ultrafine FOX-7 obtained in the above steps. The particle size distribution is shown in Figure 7 and Figure 8The particle size distribution of raw material FOX-7 is D10=30.11μm, D50=65.43μm, D90=114.3μm; the particle size distribution of FOX-7 after refinement is D10=0.293μm, D50=1.464μm, D90=3.842μm.

Claims

1. A method for preparing ultrafine explosives based on high-pressure microfluidics technology, characterized in that: The following steps are involved: (1) Preparation of explosive particle suspension Adding explosives and liquid medium into a container, inserting an ultrasonic probe into the liquid medium in the container to ultrasonically disperse the explosive particles to prepare an explosive particle suspension; (2) High-pressure microfluidization treatment The suspension is treated by using a high-pressure micro-jet homogenizer: first, a barrel is mounted on the homogenizer, and the explosive particle suspension prepared in step (1) is added into the barrel; then, high-pressure micro-jet process parameters are set; finally, a circulating water cooling device of the homogenizer is turned on, and when the temperature drops to the set temperature, the homogenizer is turned on to perform high-pressure homogenization treatment on the suspension; (3) Filtration and drying of ultrafine explosives The suspension obtained in step (2) is filtered, washed and dried to obtain ultrafine explosive particles.

2. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 1, characterized in that: The explosive in step (1) is HNS, FOX-7, RDX, HMX, DAAF, TKX-50 and LLM-105; the liquid medium in step (1) is one or a mixture of water and alcohol solvents.

3. The method for preparing ultrafine explosives based on high pressure microfluidics according to claim 1, characterized in that: The solubility of the explosive particles in the liquid medium is less than 0.1 g / ml.

4. The method for preparing ultrafine explosives based on high pressure microfluidics according to claim 1, characterized in that: In step (1), the mass ratio of explosive particles to liquid medium is 1:5 to 1:

60.

5. The method for preparing ultrafine explosives based on high pressure microfluidics according to claim 1, characterized in that: In step (1), the mass ratio of explosive particles to liquid medium is 1:10 to 1:

20.

6. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 1, characterized in that: In step (1), the length of the ultrasonic probe is 4-10 mm, the ultrasonic power is 200-300 W, and the ultrasonic treatment time is 5-20 min.

7. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 1, characterized in that: In step (2), the high-pressure micro-jet process parameters include pressure, number of cycles and circulating water temperature; the high-pressure micro-jet pressure is 35 to 150 MPa, and the number of cycles is 5 to 100 times.

8. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 7, characterized in that: In step (2), the high-pressure microjet pressure is 100-138 MPa, and the number of cycles is 30 to 70 times.

9. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 7, characterized in that: Step (2) The circulating water cooling device is set at a temperature of 0 to 10°C.

10. The method for preparing ultrafine explosives based on high pressure microfluidics technology according to claim 1, characterized in that: The filtration method in step (3) is vacuum filtration or centrifugal filtration; the drying method is water bath drying, vacuum drying or freeze drying.

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