A method and system for micro-nano hmx micro-scale continuous flow fractional crystallization preparation

Abstract

This invention relates to a continuous flow stepwise crystallization method and system for preparing micro / nano HMX at the microscale. It includes the following steps: (1) dissolving HMX in a solvent to form an HMX solution, and mixing the solvent and antisolvent to prepare a crystallization transfer solution; (2) flowing the HMX solution prepared in step (1) and the antisolvent into a primary micro-mixing crystallization unit at a desired flow ratio to generate a mixed-crystal HMX suspension with a mixed crystal particle size of 400 nm–60 μm; (3) flowing the mixed-crystal HMX suspension flowing out of the primary micro-mixing crystallization unit and the crystallization transfer solution prepared in step (1) into a secondary micro-mixing crystallization unit at a desired flow ratio, and secondary crystallizing the mixed-crystal system to obtain a pure β-HMX suspension with a crystal size in the micrometer range. This invention can obtain micro / nano β-HMX with high crystallization degree and high crystal purity by changing the mixing conditions and residence time in the secondary crystallization unit; the two-step crystallization method can meet the requirements for continuous and controllable preparation of high-quality elemental β-HMX with smaller crystal size and higher crystal purity.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials, specifically relating to a micro / nano HMX microscale continuous flow stepwise crystallization preparation method and system. Background Technology

[0002] Explosives, as the fundamental materials for producing chemical explosions, occupy an important position in both military and civilian applications. Compared with conventionally sized explosives, micro / nano-scale explosives possess certain advantages and characteristics in terms of sensitivity selectivity, critical reaction size, combustion rate, and detonation performance. Their fundamental physicochemical properties, such as reactivity, heat and mass transfer capabilities, and thermal decomposition or thermal explosion, also differ. HMX (Hypermethyl methacrylate) is currently the single-element explosive with the best overall performance. HMX exists in four crystal forms—α-, β-, γ-, and δ-—between room temperature and its melting point. Among these, the β-crystal form is the most stable and has the lowest mechanical sensitivity at room temperature and pressure, making it the preferred crystal form for applications. For homogeneous polymorphic energetic compounds, the design and control of their crystal morphology are crucial for the safe and controllable release of energy. Research on polymorphic transformation and control is also a key focus of explosive crystal form research.

[0003] In recent years, the concepts of green chemistry and desktop factories have clearly indicated that the miniaturization of chemical processes has gradually become a new model for modern chemical development. Microreactor technology, characterized by microstructured components, enhances the mass and heat transfer characteristics of fluids through microchannels, laying the foundation for efficient and safe intensification of chemical processes. Compared to macroscopic methods, microchannel reaction technology uses smaller reagent quantities, reducing the content of hazardous substances. Simultaneously, the high specific surface area and high mass and heat transfer efficiency of microscale fluid flow are unfavorable for hotspot formation, providing a more mild and controllable crystallization environment for explosive crystallization, thus possessing inherent safety. The control of the crystallization process of single-element explosives mainly relies on continuous flow. The viscous forces between the parallel-flowing inner and outer microfluids in continuous flow make it easy for the fluid layer to undergo varying degrees of lateral momentum exchange, which is beneficial for achieving multi-state flow of fluids at the microscale and controlling the crystallization environment.

[0004] The preparation of HMX by continuous flow recrystallization requires comprehensive consideration of particle size and crystal form to obtain high-quality micro / nano explosives with small particle size, narrow particle size distribution, and stable crystal phase structure. However, numerous experiments have shown that HMX samples obtained by continuous flow recrystallization in a single crystallization are usually mixed crystal systems dominated by γ-HMX, making it difficult to directly obtain high-purity β-HMX. This phenomenon can be explained by the Ostwald phase transition rule and the Gibbs free energy change rule for spontaneous processes, i.e., the first crystallization process does not precipitate the stable crystalline form β-HMX, but rather the metastable crystalline form γ-HMX. To obtain high-purity β-HMX, a stepwise crystallization method is needed, allowing the HMX mixed with different crystal forms to undergo secondary crystallization to generate the desired crystal form. Traditional macroscopic solvent-mediated crystallization processes typically have long residence times, giving the crystals sufficient growth time during the crystallization process. Although the obtained HMX products are of the stable β- form, they are often large in size, failing to meet the requirements for crystal size and morphology of high-quality elemental HMX. The stepwise crystallization method based on microchannel continuous flow technology allows metastable γ-HMX crystals to have a shorter residence time during crystal transformation in microchannels, which controls crystal growth and enables good control of the micro-nano-scale HMX crystal size during crystal transformation. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for preparing micro / nano HMX microscale continuous flow stepwise crystallization that takes into account both crystal size and crystal morphology.

[0006] The technical solution to achieve the objective of this invention is: a micro / nano HMX microscale continuous flow stepwise crystallization preparation method, comprising the following steps:

[0007] Step (1): Dissolve HMX in a solvent to form an HMX solution, and mix the solvent and antisolvent to prepare a crystallization solution;

[0008] Step (2): The HMX solution prepared in step (1) and the antisolvent are fed into the primary micro-mixing crystallization unit at the required flow ratio to generate a mixed crystal HMX suspension with a mixed crystal particle size of 400nm-60μm;

[0009] Step (3): The mixed crystal HMX suspension flowing out of the primary micro-mixing crystallization unit and the crystal transfer liquid prepared in step (1) are fed into the secondary micro-mixing crystallization unit at the required flow ratio. The mixed crystal system is then crystallized to obtain a pure β-HMX suspension with a grain size of micrometers.

[0010] Furthermore, the antisolvent is water, and the solvent is dimethyl sulfoxide, N,N-dimethylformamide, acetone, or acetonitrile.

[0011] Furthermore, the concentration of the HMX solution prepared in step (1) is 0.001 g / L-10 g / L;

[0012] In step (1), the ratio of solvent to antisolvent in the preparation of the crystallization solution is 1-10:1.

[0013] Furthermore, in step (2), the HMX solution and the antisolvent flow into the primary micro-mixing crystallization unit at a flow ratio of 1:1-20;

[0014] In step (3), the mixed crystal HMX suspension and the crystal conversion solution flow into the secondary micro-mixing crystallization unit at a flow rate ratio of 1-10:1;

[0015] The flow rate of HMX solution and antisolvent in step (2) into the primary micro-mixing crystallization unit ranges from 1 ml / min to 60 ml / L; the flow rate of mixed crystal HMX suspension and crystal transfer solution in step (3) into the secondary micro-mixing crystallization unit ranges from 1 ml / min to 60 ml / L.

[0016] Furthermore, the crystallization temperature of the primary micro-mixing crystallization unit and the secondary micro-mixing crystallization unit is 10℃-70℃.

[0017] Furthermore, the primary micro-mixing crystallization unit and the secondary micro-mixing crystallization unit are coupled with a physical field-type auxiliary crystallization unit; the physical field of the physical field-type auxiliary crystallization unit is any one or several of acoustic, optical, electrical, thermal, and magnetic fields.

[0018] A micro / nano β-HMX powder was prepared using the method described above, and the grain size of the β-HMX powder was controllable within the range of 0.8-10 μm.

[0019] A preparation system used in the above method includes a fluid-driven unit, a primary micro-mixing crystallization unit, a secondary micro-mixing crystallization unit, a collection unit, and a connecting assembly;

[0020] The HMX solution and antisolvent are respectively placed in their respective fluid drive units, and the outlet of the fluid drive unit is connected to the inlet of the primary micro-mixing crystallization unit. The outlet of the primary micro-mixing crystallization unit is connected to the inlet of the secondary micro-mixing crystallization unit. The crystallization solution is input into the inlet of the secondary micro-mixing crystallization unit through the fluid drive unit, and the outlet of the secondary micro-mixing crystallization unit is connected to the collection unit.

[0021] Furthermore, it also includes auxiliary crystallization units for assisting crystallization in the primary micro-mixing crystallization unit and the secondary micro-mixing crystallization unit;

[0022] The micro-mixing structures of the primary and secondary micro-mixing crystallization units are two-dimensional "Y"-shaped, vortex-shaped, or spiral-shaped, or three-dimensional chaotic convection-shaped.

[0023] The three-dimensional chaotic convection micro mixer consists of two chips with channels etched on them. The channels are square, circular, or triangular in shape. The channels on the two chips are arranged to be continuous in the horizontal direction to ensure that the fluid can pass through smoothly, and in the vertical direction to ensure that the fluid can produce a chaotic convection mixing effect in the mixer.

[0024] Furthermore, the system also includes an online monitoring system for acquiring real-time information on explosive crystallization kinetics.

[0025] Furthermore, the multiple primary micro-mixing crystallization units and secondary micro-mixing crystallization units are arranged in parallel. The fluid drive unit containing the HMX solution, antisolvent, and crystallization liquid has multiple outlets, which are respectively matched with the inlets of the multiple primary micro-mixing crystallization units and secondary micro-mixing crystallization units arranged in parallel.

[0026] Compared with the prior art, the significant advantages of this invention are:

[0027] 1. This application uses a microchannel continuous flow platform to prepare micro-nano β-HMX, which has a simple structure, can achieve small-dose preparation, and the experimental conditions are easy to adjust. It is very suitable for optimizing and screening experimental parameters in the process of controlling the crystal form of HMX explosives. The coupled online monitoring system can obtain the crystallization kinetics information of the explosive in real time and monitor the crystallization state of the explosive in multiple dimensions in real time.

[0028] 2. This application employs a micro-nano HMX microscale continuous flow distribution crystallization preparation method, which realizes crystal form control of micro-nano HMX in microscale continuous flow. In microchannel continuous flow, the crystal has a short residence time during the crystal transformation process, which can effectively control the crystal growth time and satisfy the requirement of complete crystal transformation while controlling the crystal size.

[0029] 3. This application employs a microscale continuous flow distribution crystallization preparation method for micro-nano HMX. Compared with traditional macroscopic methods, this method, based on microchannel continuous flow, easily achieves continuous and controllable preparation of micro-nano β-HMX. Achieving continuity not only ensures yield but also allows the micro-nano HMX suspension obtained after the first crystallization to undergo a secondary crystallization process directly in the microchannel without filtration. This enables the crystallization process to be completed while effectively controlling the crystal size, resulting in micro-nano β-HMX of superior quality.

[0030] 4. This application adopts a micro-nano HMX microscale continuous flow distribution crystallization preparation method. The preparation process is simple to operate, low in cost, short in cycle, and has a high yield. The reagents used are green and harmless. The desktop portable platform based on microchannel continuous flow is automatically controlled by computer terminal throughout the operation, which can realize rapid start-up and shutdown and fast process response. Multiple functional modules can be customized and assembled. The multi-channel parallel connection is conducive to further engineering applications in the future. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the preparation system used in this invention.

[0032] Figure 2 The HMX prepared in Example 1.

[0033] Figure 3 The HMX obtained by recrystallization in Example 1.

[0034] Figure 4 The HMX prepared in Example 2.

[0035] Figure 5 The HMX prepared in Example 3.

[0036] Figure 6 The HMX prepared in Example 4.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1-Fluid drive unit, 2-HMX solution, 3-Antisolvent, 4-Primary micro-mixing crystallization unit, 5-Transforming crystal solution, 6-Auxiliary crystallization unit, 7-Secondary micro-mixing crystallization unit, 8-Collection unit. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings.

[0040] Combination Figure 1 This application of the present invention employs a micro / nano HMX microscale continuous flow distribution crystallization preparation method, comprising a fluid driving unit 1, an HMX solution 2, an antisolvent 3, a primary micro-mixing crystallization unit 4, a crystallization transfer solution 5, an auxiliary crystallization unit 6, a secondary micro-mixing crystallization unit 7, a collection unit 8, and a connecting component.

[0041] HMX is dissolved in a solvent to form an HMX solution of a certain concentration. Water is used as the antisolvent, and the solvent and antisolvent are mixed in a certain ratio to form a crystallization solution. A fluid delivery pump is turned on and flow parameters are set to control the HMX solution and antisolvent to flow into the micro-mixing unit at a certain flow ratio. Under the efficient mixing of the solvent and antisolvent, the system reaches a high degree of supersaturation, causing HMX to crystallize out in the first stage, forming a micro / nano-sized mixed-crystal HMX suspension. The start time of the crystallization solution's transport is controlled so that it and the suspension obtained from the first crystallization are passed through a secondary crystallization unit at a certain flow ratio for crystallization. Under the solvent-mediated effect, crystal growth is controlled to generate a stable crystalline form of β-HMX. By changing the mixing conditions and residence time in the secondary crystallization unit, micro / nano β-HMX with high degree of crystallization and high crystal purity can be obtained.

[0042] This application of the present invention employs a micro / nano HMX microscale continuous flow stepwise crystallization preparation method, the specific preparation steps of which are as follows:

[0043] 1. Weigh an appropriate amount of HMX and prepare an HMX solution of a certain concentration. Water is selected as the antisolvent. Mix a certain amount of solvent and antisolvent in a certain proportion to form a crystallization solution for later use.

[0044] 2. The connecting system pipelines form primary and secondary crystallization units, enabling stable fluid transport;

[0045] 3. Turn on the fluid delivery device and set the flow parameters for primary and secondary crystallization.

[0046] 4. The prepared HMX solution and antisolvent are passed through a fluid conveying device at a certain flow rate ratio through a primary crystallization unit, so that HMX is crystallized out in one step, resulting in a suspension containing micro-nano-sized mixed crystals of HMX.

[0047] 5. After obtaining the primary crystallization suspension, control the fluid conveying device to control the transport of the crystallization liquid at an appropriate time, so that the suspension and the crystallization liquid flow into the secondary crystallization unit at a certain flow ratio for crystallization.

[0048] 6. After a certain crystallization time, a micro-nano β-HMX suspension with high crystal purity and small crystal size is obtained.

[0049] 7. The resulting suspension is washed, filtered, and dried to obtain the final micro / nano β-HMX solid sample.

[0050] The following embodiments are merely illustrative of the present invention and should not be construed as limiting the present invention.

[0051] Example 1

[0052] Micro-nano β-HMX was prepared using a microscale continuous flow stepwise crystallization method. 1 g of HMX was weighed and dissolved in 5 ml of DMSO to form a 0.2 g / ml HMX solution. 80 ml of a DMSO / H₂O crystallization solution was prepared at a 7:1 ratio and set aside. The crystallization environment was maintained at 23℃. The HMX solution was delivered using an industrial continuous injection pump at a flow rate of 5 ml / min, the antisolvent water was delivered using a continuous peristaltic pump equipped with a flow stabilizer at a flow rate of 60 ml / min, and the crystallization solution was delivered using a peristaltic pump at a flow rate of 80 ml / min. The drive unit is switched on, and the solution phase and antisolvent flow into the confocal flow primary crystallization unit under the drive of an industrial continuous injection pump and a continuous peristaltic pump, respectively. The solvent and antisolvent contact and mix rapidly in the confocal flow micromixer to form an HMX explosive suspension. During the suspension outflow, the peristaltic pump is activated to deliver the crystallization transfer liquid, allowing the crystallization transfer liquid and the suspension to flow into the dual-chamber vortex micromixing unit at their respective flow rates for secondary crystallization. Simultaneously, an ultrasonic device acting below the dual-chamber vortex micromixing unit is activated to assist the crystallization transfer process. The HMX explosive suspension after secondary crystallization is collected, washed, filtered, and dried to obtain micro / nano β-HMX solid powder, such as... Figure 2 As shown in the figure, the HMX crystals obtained after the secondary crystallization (transformation) process have a regular and full morphology, which is the crystal form (β-HMX) required for practical applications. Furthermore, under these experimental parameters, the crystal particle size can be controlled within 5-6 μm, successfully achieving the micron-scale preparation of high-purity β-HMX. A small amount of the suspension after primary crystallization was washed, filtered, and dried to obtain a solid sample, as shown in the figure. Figure 3 As shown, although the HMX sample obtained from a single crystallization exhibits effective control over crystal particle size at high flow rates, its crystal morphology is irregular, containing HMX of different crystal forms, resulting in a mixed crystal system. This makes it difficult to control the energy properties and sensitivity of HMX, affecting practical applications. Therefore, it is necessary to perform a secondary crystallization process on the HMX mixed crystal system obtained from the single crystallization to obtain β-HMX with higher crystal purity, regular morphology, and controllable particle size.

[0053] Example 2

[0054] Micro-nano β-HMX was prepared using a microscale continuous flow stepwise crystallization method. 2g of HMX was weighed and dissolved in 5ml of DMSO to form a 0.4g / ml HMX solution. 80ml of DMSO / H₂O crystallization solution was prepared at a 7:1 ratio and set aside. The crystallization environment was maintained at 23℃. The HMX solution was delivered using an industrial continuous injection pump at a flow rate of 5ml / min, the antisolvent water was delivered using a continuous peristaltic pump equipped with a flow stabilizer at a flow rate of 60ml / min, and the crystallization solution was delivered using a peristaltic pump at a flow rate of 80ml / min. With the drive unit switch turned on, the solution phase and non-solvent flow into the confocal flow primary crystallization unit, driven by an industrial continuous injection pump and a continuous peristaltic pump, respectively. The solvent and non-solvent contact and mix rapidly in the confocal flow micromixer, forming an HMX explosive suspension. During the suspension outflow, the peristaltic pump is activated to deliver the crystallization transfer liquid, allowing the crystallization transfer liquid and suspension to flow into the dual-chamber vortex micromixing unit at their respective flow rates for secondary crystallization. Simultaneously, an ultrasonic device acting below the dual-chamber vortex micromixing unit is activated to assist the crystallization transfer process. The HMX explosive suspension after secondary crystallization is collected, washed, filtered, and dried to obtain micro / nano β-HMX solid powder. Figure 4 This example increases the HMX solution concentration. In fact, at higher solution concentrations, the crystal size obtained from primary crystallization often exhibits a regular increase. However, in subsequent secondary crystallization processes, it can be observed that the crystal transformation process not only achieves a change in crystal form to ensure crystal purity but also allows for a certain degree of control over crystal size. Figure 4 The middle image shows β-HMX with high crystal purity, regular morphology, and controllable particle size (5-6 μm) obtained under these experimental parameters.

[0055] Example 3

[0056] Micro-nano β-HMX was prepared using a microscale continuous flow stepwise crystallization method. 1 g of HMX was weighed and dissolved in 5 ml of DMSO to form a 0.2 g / ml HMX solution. 40 ml of DMSO / H₂O crystallization solution was prepared at a 1:1 ratio and set aside. The crystallization environment was maintained at 23℃. The HMX solution was delivered using an industrial continuous injection pump at a flow rate of 20 ml / min, the antisolvent water was delivered using a continuous peristaltic pump equipped with a flow stabilizer at a flow rate of 20 ml / min, and the crystallization solution was delivered using a peristaltic pump at a flow rate of 20 ml / min. The drive unit is switched on, and the solution phase and non-solvent flow into the dual-chamber vortex micro-mixing primary crystallization unit under the drive of an industrial continuous injection pump and a continuous peristaltic pump, respectively. The solvent and non-solvent contact and mix rapidly in a focused flow micro-mixer to form an HMX explosive suspension. During the suspension outflow, a peristaltic pump is activated to deliver a crystallization transfer solution, allowing the crystallization transfer solution and suspension to flow into the three-dimensional chaotic convection micro-mixing unit at their respective flow rates for secondary crystallization. Simultaneously, an ultrasonic device acting below the three-dimensional chaotic convection micro-mixing unit is activated to assist the crystallization transfer process. The secondary crystallized HMX explosive suspension is collected, washed, filtered, and dried to obtain micro / nano β-HMX solid powder, such as... Figure 5 As shown. This example, compared with Example 4, analyzes the effect of the flow rates of the solution and antisolvent on crystal particle size. Under certain microchannel conditions, the residence time of the crystal in the channel (time provided for crystallization) is controlled by the flow rate. Under this ratio of crystallization solution, HMX crystals can also achieve a high degree of crystallization. Compared with the previous two examples, this example also changes the flow rate ratio of the solution to the antisolvent. At a 1 / 1 flow rate ratio, the shear effect between the solution and the antisolvent is somewhat weakened compared to a higher flow rate ratio, resulting in less control over the size of the formed crystals, leading to a trend of wider crystal diameter and increased particle size.

[0057] Example 4

[0058] Micro-nano β-HMX was prepared using a microscale continuous flow stepwise crystallization method. 1 g of HMX was weighed and dissolved in 5 ml of DMSO to form a 0.2 g / ml HMX solution. 40 ml of DMSO / H₂O crystallization solution was prepared at a 1:1 ratio and set aside. The crystallization environment was maintained at 23℃. The HMX solution was delivered using an industrial continuous injection pump at a flow rate of 15 ml / min, the antisolvent water was delivered using a continuous peristaltic pump equipped with a flow stabilizer at a flow rate of 15 ml / min, and the crystallization solution was delivered using a peristaltic pump at a flow rate of 20 ml / min. The drive unit is switched on, and the solution phase and non-solvent flow into the confocal flow primary crystallization unit, driven by an industrial continuous injection pump and a continuous peristaltic pump, respectively. The solvent and non-solvent contact and mix rapidly in the confocal flow micromixer, forming an HMX explosive suspension. During the suspension outflow, a peristaltic pump is activated to deliver a crystallization transfer solution, allowing the crystallization transfer solution and suspension to flow into the dual-chamber vortex micromixing unit at their respective flow rates for secondary crystallization. Simultaneously, an ultrasonic device acting below the dual-chamber vortex micromixing unit is activated to assist the crystallization transfer process. The HMX explosive suspension after secondary crystallization is collected, washed, filtered, and dried to obtain micro / nano β-HMX solid powder, such as... Figure 6 As shown in Example 4, the flow rates of the solution and antisolvent were reduced while maintaining a constant flow ratio. It can be seen that under this flow rate condition, the crystal particle size increased significantly, indicating that to achieve smaller particle size control, a higher flow ratio of antisolvent to solution and a higher flow rate are required.

Claims

1. A method for preparing micro / nano HMX microscale continuous flow stepwise crystallization, characterized in that, Includes the following steps: Step (1): Dissolve HMX in a solvent to form an HMX solution, and mix the solvent and antisolvent to prepare a crystallization solution; Step (2): The HMX solution and antisolvent prepared in step (1) are fed into the primary micro-mixing crystallization unit at the required flow rate ratio to generate a mixed crystal HMX suspension with a mixed crystal particle size of 400nm-60μm; Step (3): The mixed crystal HMX suspension flowing out of the primary micro-mixing crystallization unit and the crystal transfer liquid prepared in step (1) are fed into the secondary micro-mixing crystallization unit at the required flow ratio. The mixed crystal system is then crystallized to obtain a pure β-HMX suspension with a grain size of micrometers. In step (2), the HMX solution and the antisolvent flow into the primary micro-mixing crystallization unit at a flow ratio of 1:1-20; In step (3), the mixed crystal HMX suspension and the crystal conversion solution flow into the secondary micro-mixing crystallization unit at a flow ratio of 1-10:1; In step (2), the flow rate of HMX solution and antisolvent flowing into the primary micro-mixing crystallization unit ranges from 1 ml / min to 60 ml / L; in step (3), the flow rate of mixed crystal HMX suspension and crystal transfer solution flowing into the secondary micro-mixing crystallization unit ranges from 1 ml / min to 60 ml / min.

2. The method according to claim 1, characterized in that, The antisolvent is water, and the solvent is dimethyl sulfoxide, N,N-dimethylformamide, acetone, or acetonitrile.

3. The method according to claim 2, characterized in that, The concentration of the HMX solution prepared in step (1) is 0.2 g / ml or 0.4 g / ml; In step (1), the ratio of solvent to antisolvent in the preparation of the crystallization solution is 1-10:

1.

4. The method according to claim 3, characterized in that, The crystallization temperature of the primary micro-mixing crystallization unit and the secondary micro-mixing crystallization unit is 10℃-70℃.

5. The method according to claim 4, characterized in that, A physical field-based auxiliary crystallization unit is formed by coupling a primary micro-mixing crystallization unit and a secondary micro-mixing crystallization unit; the physical field of the physical field-based auxiliary crystallization unit is any one or several of the following: sound, light, electricity, heat, and magnetism.

6. A preparation system used in the method according to any one of claims 1-5, characterized in that, It includes a fluid drive unit, a primary micro-mixing crystallization unit, a secondary micro-mixing crystallization unit, a collection unit, and connecting components; The HMX solution and antisolvent are respectively placed in their respective fluid drive units, and the outlet of the fluid drive unit is connected to the inlet of the primary micro-mixing crystallization unit. The outlet of the primary micro-mixing crystallization unit is connected to the inlet of the secondary micro-mixing crystallization unit. The crystallization solution is input into the inlet of the secondary micro-mixing crystallization unit through the fluid drive unit, and the outlet of the secondary micro-mixing crystallization unit is connected to the collection unit.

7. The preparation system according to claim 6, characterized in that, It also includes auxiliary crystallization units for assisting crystallization in primary and secondary micro-mixing crystallization units; The micro-mixing structures of the primary and secondary micro-mixing crystallization units are two-dimensional "Y"-shaped, vortex-shaped, or spiral-shaped, or three-dimensional chaotic convection-shaped. The three-dimensional chaotic convection micro mixer consists of two chips with channels etched on them. The channels are square, circular, or triangular in shape. The channels on the two chips are arranged to be continuous in the horizontal direction to ensure that the fluid can pass through smoothly, and in the vertical direction to ensure that the fluid can produce a chaotic convection mixing effect in the mixer. The system also includes an online monitoring system for acquiring real-time information on explosive crystallization kinetics.

8. The preparation system according to claim 6 or 7, characterized in that, Multiple primary micro-mixing crystallization units and secondary micro-mixing crystallization units are arranged in parallel. The fluid drive unit containing the HMX solution, antisolvent, and crystallization liquid has multiple outlets, which are respectively matched with the inlets of the multiple primary micro-mixing crystallization units and secondary micro-mixing crystallization units arranged in parallel.

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