Preparation method of lunar-like soil simulant

Abstract

The invention relates to a lunar-like soil simulant preparation method which comprises the following steps: determining preparation raw materials according to chemical element information of a lunar soil sample, and drying the preparation raw materials; according to particle size distribution data of the lunar soil sample, performing jet milling operation on the dried preparation raw materials; performing grading screening on the crushed particles to obtain particles with different particle sizes; and according to the grading curve and density data of the lunar soil sample, uniformly mixing the particles with various particle sizes in proportion to obtain the simulated sample. Compared with the prior art, the lunar-soil-like simulant prepared by the method can effectively retain original corner angles and structural characteristics of particles.

Description

Technical Field

[0001] The present invention relates to the technical field of lunar soil simulation preparation, and in particular to a method for preparing a lunar soil simulant. Background Art

[0002] The Chang'e-5 landing area contains one of the youngest basaltic units on the lunar surface, and the lunar samples collected provide valuable data for studying the lunar geological age and evolutionary history. Acquisition of authentic lunar soil is extremely limited and costly in lunar exploration missions, so preparing simulants to replace authentic lunar soil for relevant experimental research is essential.

[0003] After searching, Chinese invention patent application CN115468825A discloses a method for preparing sampled simulated lunar soil, which processes the main raw materials into particles of different particle size ranges and determines the gradation of the sampled simulated lunar soil; mixes fine particles of different particle size ranges according to the gradation of the sampled simulated lunar soil, and lays coarse particles in the depth direction to form the main mixed particles of the sampled simulated lunar soil; uses the main mixed particles to obtain block-shaped simulated lunar soil with an expected dense state; splices the block-shaped simulated lunar soil horizontally or vertically to obtain a simulated lunar soil body; lays a lightweight raw material for simulating the lunar gravity field on the surface of the simulated lunar soil body, and performs surface morphology construction to obtain the sampled simulated lunar soil.

[0004] However, due to the effects of meteorite impacts and other factors, real lunar soil particles are mostly angular, sub-angular, and other shapes. The above preparation method mainly processes the main raw materials into particles of different sizes and then mixes them. During the processing, the fine particles undergo crushing, screening, and other operations, and their original edges and corners are easily eroded. It is difficult to completely retain the original edges and structural characteristics of the lunar soil particles, and it is impossible to simulate the shape of real lunar soil particles well. This may affect the similarity between the simulated lunar soil and the real lunar soil in terms of inter-particle interactions, and reduce the degree of restoration of the physical and mechanical properties of the lunar soil simulant. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for preparing a lunar soil simulant. This method takes the chemical composition, particle size distribution and density parameters of the lunar soil returned by Chang'e 5 as control targets, and realizes efficient, non-contact particle crushing and grading through airflow crushing. It can effectively retain the original edges and structural characteristics of the particles, thereby improving the degree of restoration of the simulant in physical and mechanical properties, and can provide an accurate material basis for tasks such as lunar exploration, landing testing and resource development.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The present invention provides a method for preparing a lunar soil simulant, comprising:

[0008] Determine the raw materials for preparation based on the chemical element information of the lunar soil sample and dry the raw materials;

[0009] According to the particle size distribution data of the lunar soil samples, the dried raw materials are subjected to air flow milling operation;

[0010] The crushed particles are graded and screened to obtain particles of different sizes;

[0011] According to the grading curve and density data of the lunar soil samples, particles of different particle sizes are evenly mixed in proportion to obtain simulated samples.

[0012] Preferably, the drying process of the prepared raw materials specifically includes: setting a drying temperature, measuring the mass of the raw materials at set intervals during the drying process, and recording the mass changes until the raw material mass ratio changes by less than 0.1%, and then the drying process is deemed to be completed.

[0013] Preferably, the working air pressure, grading wheel frequency and feeding frequency are set according to the particle size distribution data of the Chang'e 5 lunar soil sample, the dried preparation raw materials are subjected to air flow crushing operation, and the particles of the target particle size are extracted in combination with the centrifugal grading system.

[0014] Preferably, the airflow pulverizing operation is performed on the dried raw material according to the particle size distribution data of the Chang'e 5 lunar soil sample, including: setting the working pressure, the frequency of the grading wheel and the feeding frequency according to the particle size distribution data of the Chang'e 5 lunar soil sample, and performing the airflow pulverizing operation on the dried raw material, including:

[0015] Stage 1: Initially set the feed frequency to 60 Hz and the classifier frequency to 4 Hz to produce particles with a size range of 18 to 35 mesh;

[0016] The second stage: the feed frequency is initially set to 40 Hz and the classifying wheel frequency is set to 6 Hz to produce particles with a particle size of 35 to 100 mesh;

[0017] The third stage: the feed frequency is initially set to 15-20 Hz and the classifying wheel frequency is 8-12 Hz to produce particles with a particle size of 100-200 mesh and below;

[0018] Among them, at each stage, some sample particles are randomly selected, and the particle size distribution is detected by a laser particle size analyzer. When the mass proportion of particles with the target particle size range in the particles is less than the set proportion, the frequency of the grading wheel is fine-tuned, specifically including: when the actual prepared particles are finer than the target particle size, the frequency of the grading wheel is reduced and the feeding frequency is increased, with an adjustment step of 1 Hz; when the actual prepared particles are coarser than the target particle size, the frequency of the grading wheel is increased and the feeding frequency is reduced, with an adjustment step of 1 Hz.

[0019] Preferably, at each stage, some sample particles are randomly selected to obtain two-dimensional image data of the particles, identify particle edge information, and adjust the feeding frequency based on the aspect ratio, roundness, and sharp edge ratio of the particles.

[0020] Preferably, the feeding frequency is adjusted according to the aspect ratio, roundness and sharp corner ratio of the particles, specifically:

[0021] When the aspect ratio of the particles is within the range of 0.5 to 1.0, the roundness value of the particles is within the range of 0.299 to 0.997, and the proportion of particles with at least k sharp edges in the sample particles is greater than or equal to the set value, if any of the above conditions is not met, the feeding frequency is increased without changing the frequency of the grading wheel, with an adjustment step of 1 Hz.

[0022] Preferably, the grading and screening of the crushed particles to obtain particles of different sizes specifically includes: vibrating and screening the particles obtained by the airflow crushing operation using a combination screen with a set aperture to obtain particles of different sizes.

[0023] Preferably, the method of uniformly mixing particles of different particle sizes in proportion to obtain a simulated sample according to the gradation curve and density data of the lunar soil sample specifically includes:

[0024] Arrange the particles in descending order of their proportion and add particles of corresponding sizes for premixing;

[0025] Set the initial mixing time and stop the machine for observation at set intervals. If stratification occurs, adjust the inclination of the mixing equipment.

[0026] After the preset mixing time is reached, samples of the same mass of mixed materials are taken from multiple positions of the mixing equipment, sieved and the proportion of each particle size range is calculated. If the particle size range proportion of all samples deviates from the target gradation by less than or equal to 15%, the mixing is qualified. Otherwise, the mixing time is extended, and the set time is increased each time. The test is repeated until the standard is met to obtain a simulated sample.

[0027] Preferably, when the maximum mixing time is reached and the particle size interval ratio deviation setting value requirement is still not met, mixing is performed again.

[0028] Preferably, the mixing ratio of particles of different particle sizes is determined according to the grading curve of the lunar soil sample, specifically including: particles smaller than 1.5 mm account for 100%, with an allowable error of ±0%; particles smaller than 1 mm account for 99%, with an allowable error of ±5%; particles smaller than 0.5 mm account for 85%, with an allowable error of ±5%; particles smaller than 0.25 mm account for 51%, with an allowable error of ±5%; particles smaller than 0.15 mm account for 30%, with an allowable error of ±5%; particles smaller than 0.075 mm account for 10%, with an allowable error of ±5%.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention takes the chemical composition, particle size distribution and density parameters of the lunar soil returned by Chang'e 5 as the control target, and realizes efficient, non-contact particle crushing and classification through airflow crushing, which can effectively retain the original edges and structural characteristics of the particles, thereby improving the restoration degree of the physical and mechanical properties of the simulant, and can provide an accurate material basis for tasks such as lunar exploration, landing testing and resource development.

[0031] (2) During the drying process of the prepared raw materials, the mass changes are dynamically monitored and the drying end conditions are quantified to simulate the dry and water-free state of the real lunar surface. This not only meets the core requirements of lunar soil simulants for low water content and high uniformity, but also provides a scientific basis for the standardization and traceability of the preparation process. It is a key link in ensuring the quality of the simulants and the reliability of subsequent experiments.

[0032] (3) During the air flow milling operation, the raw materials can be efficiently crushed by precisely controlling the air pressure, grading wheel and feeding frequency. The target particle size can be accurately extracted by combining centrifugal classification, and the particle size distribution is narrow, the purity is high and the adaptability is strong.

[0033] (4) Based on the multi-angular and multi-crack characteristics of lunar soil caused by meteorite impacts, the particle morphology is converted from a qualitative description to a measurable quantitative parameter through the particle aspect ratio and roundness index, which greatly ensures the consistency of the morphology of the simulated object with the real lunar soil.

[0034] (5) Add particles of corresponding particle sizes in descending order according to the proportion of particle size, and pre-mix them first. Add large particle size particles first to form a stable base, and then fill the gaps with small particle size particles, so as to reduce the stratification or agglomeration of particles due to particle size differences, avoid the concentrated accumulation of small particles, and make the distribution of particles of different particle sizes more balanced.

[0035] (6) By sampling at different positions and depths, testing the same quality, and comparing the deviation with the target gradation, the mixing uniformity is strictly verified from the two aspects of spatial distribution and quantitative indicators to avoid imbalance in local particle size distribution and ensure that the simulated sample as a whole meets the gradation requirements. At the same time, the mixing time is dynamically adjusted by pre-set time, deviation judgment, and step-by-step extension of the mixing time, which not only avoids the destruction of particle morphology caused by excessive mixing, but also prevents the influence of insufficient mixing on uniformity, thus balancing efficiency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Flow chart of the method of the present invention.

[0037] Figure 2 Chemical element maps of the simulated lunar soil and Chang'e 5 lunar soil samples prepared in the examples.

[0038] Figure 3 This is a particle grading curve diagram of the simulated lunar soil and Chang'e 5 samples prepared in the examples.

[0039] Figure 4 Schematic diagram of the microscope viewing angle for preparing lunar soil samples in the embodiment;

[0040] Figure 5 The simulated lunar soil internal friction angle prepared in the example and the predicted in-situ internal friction angle range of the Chang'e 5 lunar soil are shown. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0042] Example

[0043] like Figure 1 As shown, this embodiment provides a method for preparing a lunar soil simulant, which is suitable for scenarios such as lunar soil sampling, probe landing performance verification, and extraterrestrial environment simulation. The method includes the following steps:

[0044] S1. Determine the preparation raw materials based on the chemical element information of the lunar soil sample and dry the prepared raw materials.

[0045] Based on the chemical element information of the Chang'e-5 lunar soil samples, volcanic slag particles from Huinan County, Jilin Province, China were selected as raw materials for preparation. Before preparation, the raw materials were dried to simulate the dry and waterless state of the real lunar surface, and their moisture content was tested until the moisture content of the sample was close to zero.

[0046] Specifically, the drying temperature is set (set to 200°C in this embodiment), and the raw material mass is measured at set intervals (every 30 minutes in this embodiment) during the drying process, and the mass change is recorded until the raw material mass ratio changes by less than 0.1%, and the drying process is considered complete.

[0047] S2. Based on the particle size distribution data of the lunar soil sample, the dried raw materials are subjected to air flow pulverization operation.

[0048] This embodiment uses airflow crushing, which can effectively avoid the surface passivation and rounding effects of particles easily caused by traditional ball milling methods, retain the original edges and crack structures, and thus improve the similarity between the simulant and the Chang'e 5 lunar soil in particle morphology, structural fragmentation and particle size distribution.

[0049] Scanning electron microscopy, stereo microscope and micro-CT technology were used to analyze the Chang'e-5 lunar soil samples to obtain data such as their particle morphology and particle size distribution, providing a reference basis for the preparation of simulated lunar soil.

[0050] The grading information of the Chang'e-5 lunar soil samples is shown in Table 1 below, including: particles smaller than 1.5 mm account for 100%, with an allowable error of ±0%; particles smaller than 1 mm account for 99%, with an allowable error of ±5%; particles smaller than 0.5 mm account for 85%, with an allowable error of ±5%; particles smaller than 0.25 mm account for 51%, with an allowable error of ±5%; particles smaller than 0.15 mm account for 30%, with an allowable error of ±5%; particles smaller than 0.075 mm account for 10%, with an allowable error of ±5%.

[0051] Table 1. Grading information of Chang'e-5 lunar soil samples

[0052] The proportion of particles smaller than this size Particle size (mm) Allowable error 100％ 1.5 ±0％ 99％ 1.0 ±5％ 85％ 0.5 ±5％ 51％ 0.25 ±5％ 30％ 0.15 ±5％ 10％ 0.075 ±5％

[0053] Based on the particle size distribution data of the Chang'e-5 lunar soil sample, the working pressure, classifier frequency, and feed frequency were set. The dried raw materials were subjected to airflow pulverization, and the target particle size was extracted in combination with the centrifugal classification system. Specifically, the following steps were performed:

[0054] Stage 1: The feed frequency was initially set to 60 Hz and the classifying wheel frequency was set to 4 Hz to produce particles with a particle size of 18 to 35 mesh.

[0055] The second stage: the feed frequency was initially set to 40 Hz and the classifying wheel frequency was set to 6 Hz to produce particles with a particle size of 35 to 100 mesh.

[0056] The third stage: the feed frequency is initially set to 15-20 Hz and the classifying wheel frequency is 8-12 Hz to prepare particles with a particle size of 100 mesh to 200 mesh and below.

[0057] At each stage, a portion of sample particles is randomly selected and the particle size distribution is detected using a laser particle size analyzer. When the mass proportion of particles in the target particle size range is greater than a set proportion (in this embodiment, set to 80%), the preparation parameters are reasonable. If the mass proportion of particles in the target particle size range of the particles actually prepared is less than 80% of the detected mass, there are two situations: when the actual prepared particles are finer than the target particle size, it is necessary to reduce the grading wheel and increase the feeding frequency, with an adjustment step of 1 Hz; when the actual prepared particles are coarser than the target particle size, it is necessary to increase the grading wheel and reduce the feeding frequency, with an adjustment step of 1 Hz.

[0058] During the preparation phase, a random sample of particles is randomly selected, and two-dimensional image data is acquired. Particle edge information is identified, and particle shape characteristics are calculated. Airflow milling parameters are adjusted accordingly. Specifically, the particle aspect ratio, roundness, and percentage of sharp corners are calculated. If the particle morphology parameters match the target particle morphology standard, the simulated sample particle morphology meets the specifications and no adjustments are required. Otherwise, fine-tuning of the airflow milling parameters is performed.

[0059] In this embodiment, the target particle morphology characteristic standards are: the aspect ratio is in the range of 0.5 to 1.0, the roundness value of the particles is in the range of 0.299 to 0.997, and the proportion of particles containing at least k sharp edges in the sample is greater than or equal to the set value (in this embodiment, k is set to 2).

[0060] Specifically, the particle morphology calculation process includes:

[0061] 1) Image acquisition: Take the particles to be tested and place them in the center of the microscope sample stage, ensuring that there is no overlap between particles. Adjust the microscope light source, magnification, and focal length to ensure that the sample image is clearly visible, with each field of view containing 20-50 particles.

[0062] 2) Image preprocessing and particle segmentation: The image acquisition system acquires the sample image, uses the segmentation algorithm to separate the particles from the background, and generates a binary image;

[0063] 3) Particle edge feature extraction: Use edge detection algorithm to extract particle contours and obtain the position coordinates of particle edge pixel points to prepare for particle morphological parameter calculation;

[0064] 4) Calculation of particle morphology parameters:

[0065] Aspect ratio: The ratio of the short axis b to the long axis a of the fitted ellipse (i.e., b / a). The aspect ratio range is (0, 1). A larger aspect ratio indicates that the particle shape is closer to a circle.

[0066] Circularity ψ describes the difference between irregular particles and circular shapes. The range of particle circularity is (0, 1). The greater the circularity, the closer the particle shape is to a circle. Its formula is as follows:

[0067]

[0068] Sharp corners: For each point on the contour, take the five sampling points before and after it to fit two straight lines, and calculate the angle θ between the two straight lines. If θ<90°, mark the current point as a sharp corner.

[0069] S3. Classify and screen the crushed particles to obtain particles of different sizes.

[0070] In this embodiment, the particles obtained by the airflow crushing operation are vibrated and screened using a combination of sieves with set apertures to obtain particles of different particle sizes. Specifically, the crushed sample is screened in sequence through sieves with apertures of 18, 35, 65, 100, and 200 mesh to obtain five particle size components, which are then sealed and stored.

[0071] S4. According to the grading curve and density data of the lunar soil sample, particles of different particle sizes are evenly mixed in proportion to obtain a simulated sample.

[0072] 1) Arrange the particles in descending order of their proportion and add particles of corresponding sizes for premixing;

[0073] 2) Set the initial mixing time and stop the machine for observation at set intervals. If stratification occurs, adjust the inclination angle of the mixing equipment;

[0074] 3) After the preset mixing time is reached, samples of the same mass of the mixed material are taken from multiple locations of the mixing equipment, sieved, and the proportion of each particle size range is calculated. If the particle size range proportions of all samples deviate from the target gradation by less than or equal to 15%, the mixture is qualified. Otherwise, the mixing time is extended, and the set time is increased each time. The test is repeated until the target is met to obtain a simulated sample. If the particle size range proportion deviation setting value is still not met after the maximum mixing time is reached, mixing is repeated.

[0075] Next, the performance of the lunar soil simulant prepared in this embodiment was verified.

[0076] (1) Chemical property test verification

[0077] The chemical composition of the test samples was analyzed by X-ray fluorescence spectroscopy. Figure 2 In this example, volcanic slag particles from Huinan County, Jilin Province, China were selected as the raw material for preparation. The main chemical elements of the lunar soil simulant, a lunar soil sample, are similar to those of the Chang'e 5 lunar soil sample, with a SiO2 content of 48%, an Al2O3 content of 17%, a Fe2O3 content of 12%, and a CaO content of 7%.

[0078] (2) Physical property test verification

[0079] Statistical analysis of the particle distribution of Chang'e 5 lunar soil samples, including the distribution of particle quantity and mass, Figure 3 As shown in part (a); the gradation curves of the simulated lunar soil sample and the Chang'e 5 lunar soil sample are shown in Figure 3 As shown in part (b), the particle gradation of the simulated lunar soil is between the upper and lower limits of the historical lunar soil particle size, and the gradation error with the Chang'e 5 lunar soil is less than 15%, which well simulates the gradation characteristics of the Chang'e 5 lunar soil.

[0080] In addition, in order to further analyze the morphological characteristics of the crushed particles, the simulated lunar soil samples were observed using a scanning electron microscope. Figure 4 The results show that the particles retain distinct angular shapes, irregular fracture surfaces, and fine cracks on their surfaces, demonstrating that airflow pulverization effectively preserves the natural morphology and structural characteristics of the particles without mechanical contact. This morphological feature is consistent with the multi-angular and multi-cracked particle structure of the Chang'e-5 lunar soil sample, helping to improve the fidelity of the simulated lunar soil in mechanical properties such as friction angle and shear strength.

[0081] (3) Mechanical properties test verification

[0082] Before conducting mechanical properties tests, the in-situ internal friction angle value of the Chang'e-5 lunar soil was calculated and used as a reference value for shear strength tests based on the internal friction angle.

[0083] Specifically, the panoramic camera images of Chang'e-5 were obtained, and the in-situ internal friction angle value of the Chang'e-5 lunar soil was calculated through the settlement, touchdown speed, foot pad density and radius, lunar soil density and particle size data of the Chang'e-5 lander foot pad (Table 2), providing a mechanical reference for the preparation of simulated lunar soil.

[0084] Table 2 Calculation parameters of the in-situ internal friction angle of lunar soil in the Chang'e-5 landing area

[0085] parameter Numerical Foot pad radius (m) 0.25 <![CDATA[Foot pad density (g / cm 3 )]]> 2.74 Ground contact speed (m / s) 1.99 Settlement depth (cm) 3～5 Median particle size (μm) 52.5 <![CDATA[Lunar soil density (g / cm 3 )]]> 1.2

[0086] The calculation formula for the in-situ internal friction angle of the Chang'e-5 lunar soil is as follows:

[0087]

[0088] in, is the internal friction angle of the target particle, r is the particle size of the target particle, a is the radius of the foot pad, d is the sedimentation depth of the foot pad, δ is the density of the foot pad, ρ is the density of the target particle, u is the foot pad contact velocity, and g is the gravitational acceleration of the moon.

[0089] Parameters like the internal friction angle and cohesion of real lunar soil are closely related to the interlocking action of particle edges and the continuity of the gradation. If the angular characteristics of fine particles are destroyed, the mechanical locking effect between simulated lunar soil particles is weakened, resulting in low parameters like the internal friction angle. In this embodiment, airflow milling achieves efficient, non-contact particle crushing and grading, effectively preserving the original angular and structural characteristics of the particles. This improves the fidelity of the simulant's physical and mechanical properties, providing an accurate material foundation for missions such as lunar exploration, landing testing, and resource development.

[0090] Specifically, in the embodiment, a conventional triaxial test was conducted (confining pressure was set to 25, 50 and 75 kPa), the sample size was 50 mm in diameter and 100 mm in height, sealed with a sealing rubber film and kept dry. The test was loaded to failure under constant strain rate conditions. The dry density was 1.2 g / cm 3 The internal friction angle of the simulated lunar soil is 36.9°. Figure 5 As shown, the internal friction angle value of the simulated lunar soil is within the predicted range of the in-situ internal friction angle of the Chang'e 5 lunar soil, indicating that the simulant of the present invention has a high degree of restoration in terms of mechanical properties.

[0091] In summary, the present invention adopts an airflow crushing process and is controlled by the particle grading and density of the Chang'e-5 lunar soil. The preparation method is characterized by high efficiency, simple process, and large-scale production. The prepared simulated lunar soil is similar to the Chang'e-5 lunar soil in chemical composition, physical and mechanical properties, and can be used as a substitute for the Chang'e-5 lunar soil, providing a basis and support for the smooth implementation of resource utilization and construction tasks in my country's lunar exploration mission.

[0092] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for preparing a lunar soil simulant, characterized in that: include: Determine the raw materials for preparation based on the chemical element information of the lunar soil sample and dry the raw materials; According to the particle size distribution data of the lunar soil samples, the dried raw materials are subjected to air flow milling operation; The crushed particles are graded and screened to obtain particles of different sizes; According to the grading curve and density data of the lunar soil samples, particles of different particle sizes are evenly mixed in proportion to obtain simulated samples.

2. The method for preparing a lunar soil simulant according to claim 1, characterized in that: The drying process of the prepared raw materials specifically includes: setting a drying temperature, measuring the mass of the raw materials at set intervals during the drying process, and recording the mass change until the raw material mass ratio changes by less than 0.1%, and then the drying process is considered to be completed.

3. The method for preparing a lunar soil simulant according to claim 1, characterized in that: The method comprises: setting the working air pressure, the grading wheel frequency and the feeding frequency according to the particle size distribution data of the Chang'e-5 lunar soil sample, performing an air flow pulverizing operation on the dried preparation raw material, and extracting particles of the target particle size in combination with a centrifugal grading system.

4. The method for preparing a lunar soil simulant according to claim 3, characterized in that: The method includes setting the working pressure, the frequency of the classifying wheel, and the feeding frequency according to the particle size distribution data of the Chang'e 5 lunar soil sample, and performing a jet milling operation on the dried raw material, including: Stage 1: Initially set the feed frequency to 60 Hz and the classifier frequency to 4 Hz to produce particles with a size range of 18 to 35 mesh; The second stage: the feed frequency is initially set to 40 Hz and the classifying wheel frequency is set to 6 Hz to produce particles with a particle size of 35 to 100 mesh; The third stage: the feed frequency is initially set to 15-20 Hz and the classifying wheel frequency is 8-12 Hz to produce particles with a particle size of 100-200 mesh and below; Among them, at each stage, some sample particles are randomly selected, and the particle size distribution is detected by a laser particle size analyzer. When the mass proportion of particles with the target particle size range in the particles is less than the set proportion, the frequency of the grading wheel is fine-tuned, specifically including: when the actual prepared particles are finer than the target particle size, the frequency of the grading wheel is reduced and the feeding frequency is increased, with an adjustment step of 1 Hz; when the actual prepared particles are coarser than the target particle size, the frequency of the grading wheel is increased and the feeding frequency is reduced, with an adjustment step of 1 Hz.

5. The method for preparing a lunar soil simulant according to claim 3, characterized in that: At each stage, some sample particles are randomly selected to obtain two-dimensional image data of the particles, identify the edge information of the particles, and adjust the feeding frequency according to the aspect ratio, roundness and proportion of sharp edges of the particles.

6. The method for preparing a lunar soil simulant according to claim 5, characterized in that: The feeding frequency is adjusted according to the aspect ratio, roundness and sharp corner ratio of the particles, specifically: When the aspect ratio of the particles is within the range of 0.5 to 1.0, the roundness value of the particles is within the range of 0.299 to 0.997, and the proportion of particles with at least k sharp edges in the sample particles is greater than or equal to the set value, if any of the above conditions is not met, the feeding frequency is increased without changing the frequency of the grading wheel, with an adjustment step of 1 Hz.

7. The method for preparing a lunar soil simulant according to claim 1, characterized in that: The grading and screening of the crushed particles to obtain particles of different particle sizes specifically includes: vibrating and screening the particles obtained by the airflow crushing operation using a combination screen with a set aperture to obtain particles of different particle sizes.

8. The method for preparing a lunar soil simulant according to claim 1, characterized in that: According to the gradation curve and density data of the lunar soil sample, particles of different particle sizes are uniformly mixed in proportion to obtain a simulated sample, specifically including: Arrange the particles in descending order of their proportion and add particles of corresponding sizes for premixing; Set the initial mixing time and stop the machine for observation at set intervals. If stratification occurs, adjust the inclination of the mixing equipment. After the preset mixing time is reached, samples of the same mass of mixed materials are taken from multiple positions of the mixing equipment, sieved and the proportion of each particle size range is calculated. If the particle size range proportion of all samples deviates from the target gradation by less than or equal to 15%, the mixing is qualified. Otherwise, the mixing time is extended, and the set time is increased each time. The test is repeated until the standard is met to obtain a simulated sample.

9. The method for preparing a lunar soil simulant according to claim 8, characterized in that: When the maximum mixing time is reached and the particle size range ratio deviation setting value requirement is still not met, mixing is performed again.

10. The method for preparing a lunar soil simulant according to claim 1, characterized in that: The mixing ratio of particles of different particle sizes is determined according to the grading curve of lunar soil samples, specifically: particles smaller than 1.5 mm account for 100%, with an allowable error of ±0%; particles smaller than 1 mm account for 99%, with an allowable error of ±5%; particles smaller than 0.5 mm account for 85%, with an allowable error of ±5%; particles smaller than 0.25 mm account for 51%, with an allowable error of ±5%; particles smaller than 0.15 mm account for 30%, with an allowable error of ±5%; particles smaller than 0.075 mm account for 10%, with an allowable error of ±5%.

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