Design and Experimental Investigation of Pneumatic Drum-Sieve-Type Separator for Transforming Mixtures of Protaetia Brevitarsis Larvae

Abstract

In response to the need for separation and utilization of residual film mixtures after transformation of protaetia brevitarsis larvae, a pneumatic drum-sieve-type separator for transforming mixtures of protaetia brevitarsis larvae was designed. First, the suspension velocity of each component was determined by the suspension speed test. Secondly, the separation process of residual film, larvae, and insect sand was formulated on the basis of biological activities, shape differences, and aerodynamic response characteristics. Eventually, the main structural parameters and working parameters of the machine were determined. In order to optimize the separation effect, a single-factor experiment and a quadratic regression response surface experiment containing three factors and three levels were carried out, and the corresponding regression model was established. The experimental results showed that the effects of the air speed at the inlet, inclination angle of the sieve cylinder, and rotational speed of the sieve cylinder on the impurity rate of the residual film decreased in that order, and that the effects of the rotational speed of the sieve cylinder, inclination angle of the sieve cylinder, and air speed at the inlet on the inactivation rate of the larvae decreased in that order. Through parameter optimization, a better combination of working parameters was obtained: the rotational speed of the sieve cylinder was 24 r/min, the inclination angle of the sieve cylinder was −0.43°, and the air speed at the inlet was 5.32 m/s. The average values of residual film impurity rate and larval inactivation rate obtained from the material sieving test under these parameters were 8.74% and 3.18%, with the relative errors of the theoretically optimized values being less than 5%. The results of the study can provide a reference for the resource utilization of residual film and impurity mixtures and the development of equipment for the living body separation of protaetia brevitarsis.

1. Introduction

Farmland film cover cultivation technology contributes significantly to enhancing crop yields and promoting the economic benefits of farmers [1,2,3]. However, with the yearly growth of cotton planting area, the total amount of film used has been increasing, leading to the increasingly serious problem of residual film (residual plastic film from agricultural fields) pollution in Xinjiang [4]. Existing studies have indicated a long degradation period for film, which is characterized by a significant reduction in crop yields over long periods of time. Although centralized mechanized film harvesting after autumn alleviated the residual film pollution in cotton fields to a certain extent, the highly flexible and ductile film is tightly entangled with cotton stalks, soil, and other impurities, which makes the residual film pollution problem transfer from the field to the yard, and the white pollution problem still exists [5].

In recent years, in order to solve the problem of resource utilization in the mechanical harvesting of residual film, mechanical sorting, washing, high-temperature cracking, and other related technologies have provided diversified research directions, but these technologies are difficult to be applied in large quantities due to their capacity constraints and overall conversion benefits [6,7]. Mechanical primary separation, as a prerequisite for residual film reprocessing, faces challenges such as high percentages of straw, sand, and soil wastes, the absence of a site for stockpiling, and the difficulty of separating residual film and straw, as shown in Figure 1. As carrion grubs, protaetia brevitarsis larvae have a strong ability to transform a wide range of organic wastes. Studies have shown that the conversion rate of protaetia brevitarsis larvae to crude fibers, such as corn straw, wheat straw, and cotton straw, is as high as 63.82% ± 30.90%, and that 1 t of protaetia brevitarsis can transform 15~18 t of straw [8,9,10]. As shown in Figure 2, the fermented cotton stalk residual film mixture was fed on by white starry-eyed golden tortoise beetle larvae, which greatly reduced the difficulty of separating the residual film and cotton stalk [11], so the use of living ecological effects can realize the non-polluting transformation of farmland waste. Drum sieves are widely used in domestic waste cleaning, grading, threshing, and sieving machinery due to their simple structure and remarkable sieving effect. In the field of agricultural mechanization, drum sieves, as a kind of high-efficiency classification and sieving equipment, have been widely used in the processing of a variety of materials [10]. In their study on the movement law and sieving characteristics of rice threshing mixture in a cylindrical sieve, Yuan et al. [12] revealed the relationship between the trajectory of the material’s movement and the screening efficiency. Considering the need for continuous and uniform discharge, Sharma et al. [13] designed a rotary orifice feeding system to provide a reference for solving similar problems. In the case of a maize cleaning and sorting device, the design and performance optimization of the buried sieve demonstrates the significant enhancement of the separation effect by structural innovations [14]. Chen et al. [15] studied the mechanism of pneumatic separation for rice husk and brown rice based on the CFD-DEM coupling method, which provided theoretical guidance for the design of high-efficiency air separation equipment. Kong et al. [16] numerically simulated the breakage of feed particles during pneumatic conveying to provide a reference for optimizing conveying parameters and reducing particle breakage. The researchers revealed the relationship between particle motion behavior and mixing efficiency through numerical simulation of the mixing motion pattern of rice particles in a rotating drum [17,18,19]. Zhao et al. [20], based on discrete element simulation (DEM) and Taguchi’s orthogonal design of experiments methodology, optimized a circular vibrating sieve to improve its sieving efficiency and performance. Wang et al. [21] designed a drum-type buckwheat thresher according to the distribution law of the dislodged material in order to realize the efficient threshing of buckwheat. Although cylinder sieves have been applied in a variety of fields, their application in the separation of mixtures of living organisms is still relatively rare. As an insect with strong transforming ability, protaetia brevitarsis larvae can be applied to batch film miscellaneous separation, breaking the bottleneck of green application of the resource. This type of conversion increases the output of biological proteins and fertilizers. We combine airflow sorting and drum screening treatment to accomplish the separation and collection of the larvae and the residual film. Under low-loss conditions, the larvae can be used as breeding seed worms, which can provide the basis for rapid breeding and batch application, significantly improve the utilization rate of resource recycling, and provide an integrated application paradigm of “treatment-breeding” for the film hybrid bioconversion industry (the use of insects and microorganisms as synergistic solid waste resource treatment technology).

In order to realize the effective separation of insect sand, residual film, larvae, and other materials, this paper designed a pneumatic drum-sieve-type separator for transforming mixtures of protaetia brevitarsis larvae. It integrates drum screening, air blowing, and secondary air separation to achieve multi-channel separation of mixtures. The main structural parameters and working parameters of the machine were determined by analyzing the movement process of materials. The working parameter combinations were optimized by a single-factor experiment and a quadratic regression response surface experiment containing three factors and three levels, and the separation effect was verified. This study provides a new way and technical reference for the application of residual film mixtures and the resource utilization of residual film and impurities.

2. Determination of Material Parameters of Conversion Mixtures

The protaetia brevitarsis larvae mixtures studied in this paper originated from a scientific research center for the industrialization of insects in Manas County, Xinjiang Province. Before the fermentation of the mixtures of residual film and impurities, the mixtures are crushed by a disintegrator to ensure that the length of the crushed residual film is less than 10 cm, and the crushed materials are mixed with cow dung and a fermentation agent to be stacked for fermentation. After the fermentation is finished, the mixtures are given to the protaetia brevitarsis larvae to feed on. After the larvae have grown to third instar larvae, the sampled material is the product of feeding and is ready for sorting. As shown in Figure 3, the mixtures contained four main components: larvae, insect sand, residual film, and a small number of impurities (incompletely fed straw). The mass ratio of each component material was known to be 1:8.78:0.02:0.2 by sorting and weighing. Due to the low mass proportion of impurities, which are mainly composed of fermented cow dung, sand, straw residue and other substances, there is no significant difference in particle size and appearance between these impurities and insect sand. From a functional point of view, these impurities and insect sand can be used together as organic fertilizer. Therefore, in the subsequent sieving process, these impurities are considered as a part of the insect sand.

2.1. Determination of Physical Parameters of Mixture

The aerodynamic properties of the materials are mainly affected by their own moisture content, density, and size. For this reason, the project team randomly selected test samples from the mixture and sorted them according to their composition. The moisture content of insect sand was measured as 42.15% by using an SYF-6 halogen rapid moisture meter. Normal growing larvae of protaetia brevitarsis were selected to measure the densities of larvae and insect sand, which were 940 kg/m³ and 433 kg/m³, respectively. The density of the residual film was found to be 930 kg/m³ by the relevant data [22]. The dimensions of the insect sand, protaetia brevitarsis larvae, and residual film were measured separately. The sliding friction angle was measured by an angle of repose test [23,24]. The measurement results are shown in

Table 1. Shape parameters and contact parameters of each component in mixture.

Material	Length/(mm)	Height/(mm)	Thickness/(mm)	Angle of Repose/(°)	Sliding Friction Angle/(°)
larvae	35~40	10~12	/	30	24
insect sand	3~4	2	/	40	35
residual film	50~100	40~100	0.01	/	/

.

2.2. Suspension Velocity of Transformants

In order to determine the actual suspension velocity of each material, the protaetia brevitarsis larvae, insect sand, and residual film from randomly selected mixtures were manually sieved according to their composition. The components were weighed by using an electronic scale to obtain a sufficient amount of test samples. During the test, materials of the same composition were placed on a damping net from the feeding port, and then the fan was started. The wind speed was controlled by adjusting the frequency converter, and the frequency of the frequency converter was gradually adjusted to make the wind gradually increase until the materials reached their dynamic equilibrium state within a certain range of the conical observation tube [25]. The frequency value on the inverter was recorded when each material reached the suspended state. We closed the fan and waited for the measured materials to settle before removing them. We then restarted the fan and adjusted the frequency converter to the recorded value; a wind speed tester was used to measure the wind speed at three speed holes (from top to bottom) in the conical observation tube. At this time, the average of the values measured by the three speed holes was the suspension speed of the material. The test setup is shown in Figure 4.

The suspension velocities of protaetia brevitarsis larvae were 12.97 m/s, 13.32 m/s, and 14.12 m/s. The suspension velocities of insect sand were 6.58 m/s, 7.07 m/s, and 7.75 m/s. The suspension velocities of residual film were 1.09 m/s, 1.56 m/s, and 2.08 m/s. The mean suspension velocities of the three materials were 13.47 m/s, 7.13 m/s, and 1.58 m/s, respectively. Comparison of these mean velocity values clearly shows that there is a significant difference in the suspended velocity test values between larvae, insect sand, and residual film, with an approximate multiplicative relationship. Specifically, the suspension velocities of the materials are, in descending order, protaetia brevitarsis larvae, insect sand, and residual film. In addition, as a flexible material, the characteristic length of residual film will be dynamically transformed under the action of external load. Referring to the literature, the suspension velocity of residual film is about 0.90 m/s, but because the residual film was not in a fully extended state in the actual measurement, the measured suspension velocity was high. In view of these velocity differences, it is appropriate to sieve the protaetia brevitarsis larvae mixtures by wind-sorting. Preliminarily, it was determined that the range of variation in airflow separation speed for materials suitability should be between 2.08 and 6.58 m/s.

3. Structure and Working Principle of Whole Machine

3.1. Structure of the Whole Machine

According to the results of the study of the suspension speed of the protaetia brecitarsis larvae mixtures in the above content, the design of a pneumatic tumbler-sieve-type protaetia brecitarsis larvae transformed mixture separator is shown in Figure 5, which is mainly composed of a fan, electric motor, control cabinet (containing frequency converter), winch, sieve cylinder, spiral blades, the lower open mesh box, and other components. The sieve cylinder is supported by a stand by means of a tug wheel, and the inner wall of the sieve cylinder is arranged with double-ended, equal-pitch spiral blades. The front fan and the lower open mesh box are located at the front and rear ends of the sieve cylinder. The winch is placed directly under the round hole section of the sieve cylinder. A frequency converter regulates the speed of the front fan and the sieve cylinder, respectively.

3.2. Working Principle

After the mixed materials enter the sieving system from the inlet, the whole sieving process is divided into the following three steps: (1) Preliminary separation by airflow: The airflow generated by the front fan firstly contacts with the mixed material, and the residual film is blown directly to the film collection box at the end of the sieve cylinder due to its lighter quality and sensitivity to the airflow effect, thus realizing the preliminary separation of the residual film, and the inlet wind speed is set at 3~7 m/s according to the airflow fugitive effect. (2) Screw conveying of the larvae and sieving of the insect sand: The insect sand and the larvae are continuously conveyed to the end of the sieve cylinder under the push of the spiral blades. During the rolling process, the smaller insect sand can penetrate through the mesh of the sieve drum and become the sieved material. This sieved insect sand material is concentrated through the lower shell after falling into the winch, and is then conveyed by the winch to the exit; the larger white star beetle larvae continue to be conveyed by the turning action of the spiral blade to the end of the sieve drum, from the long circular holes and down through the sieve, to achieve the separation of the larvae and the insect sand. (3) Second wind selection of insect film: In the process of separation, due to the overlapping of the windward side of the mixed material and the overlaying, part of the residual film may be curled into a ball, which cannot be blown out by the airflow of the front fan. In order to enhance the separation effect of the larvae, the discharge port below is arranged with a deflector separator plate in the front of the additional axial fan (wind speed of 3~5 m/s) at the back end of the open mesh box towards the bottom. The airflow from the axial fan at the rear end is blown over the upper surface of the flow-guiding plate, so that the residual film falling with the larvae is subjected to airflow and finally blown to the lower open net box, which realizes the secondary separation of the residual film and the larvae.

4. Key Component Design and Parameter Analysis

4.1. Design of Segmented Sieve Cylinder

In order to prevent the residual film from hanging on the inner wall of the sieve cylinder, making it difficult to be blown out by the airflow, the main body of the sieve cylinder is made of a perforated sieve with a smooth inner wall. The perforations are composed of round and long circular holes, which are used for sieving insect grit and larvae, respectively. These are combined with double-ended helical blades on the inner wall of the circular hole section, and the outer wall surface is configured with a limit ring, which is located on top of the V-type articulated support composed of a tug wheel in the working state, and rotates the sieve cylinder by driving the tug wheel set. The structure is shown in Figure 6.

4.1.1. Determination of Perforations of Sieve Cylinder

In the sieving process, the sieving efficiency is positively correlated with the effective coefficient of sieve area. The shape of the insect sand approximates an ellipsoid, with its measured grain size averaging 2.5 mm and its long-axis length reaching 4 mm. Due to its shape and size characteristics, the insect sand sieving stage uses a circular-hole-shaped sieve surface. The elongated larvae have the approximate shape of an elongated cylinder, with a measured diameter averaging 12 mm and a length up to 40 mm. In response to this size characteristic, the larvae sieving stage selects a long circular-hole sieve surface and uses a triangular arrangement with a greater coefficient of effectiveness of the sieve surface area [26,27]. The exact layout of the sieve hole arrangement is shown in Figure 7.

Considering processing convenience, the circular sieve holes are designed with a rectangular arrangement, and the circular sieve hole diameter d₀ and hole distance l₀ need to be satisfied as follows:

$$\left\{\begin{array}{l}{d}_0=k_s·d_{\max }\\ l_0\ge 2d_0\end{array}\right.$$

(1)

In the formula, k_s is the pore size coefficient, taking 1.3, and d_max is the maximum particle size, mm.

Substituting the profile parameters of the insect sand into Equation (1) results in a sieve hole diameter of 5.2 mm, rounded to 5 mm, and a hole distance of 20 mm.

The length and diameter of the larvae are relatively large, the width of the long circular holes can be calculated as 15.6 mm with reference to the circular sieve hole, and the rounded d_c is 16 mm. The length of the long circular hole d_l is designed to be 66 mm, the transverse hole spacing l_x to be 36 mm, and the longitudinal hole spacing l_y to be 85 mm.

The effective coefficient of the sieve surface area is shown in Equation (2).

$$\left\{\begin{array}{c}{K}_1={\displaystyle \frac{\pi d_0^2}{4{\left(l_s+d_0\right)}^2}}\\ K_2={\displaystyle \frac{d_c{d}_l-(1-\frac{\pi }{4})d_c^2}{l_x{l}_y}}\end{array}\right.$$

(2)

In the formula, K₁ is the effective coefficient of the sieve surface area of the circular hole section; K₂ is the effective coefficient of the sieve surface area of the long circular hole section; and l_s is the sieve hole margin (l_s = l₀ − d₀), mm.

Calculations give K₁ as 0.196 and K₂ as 0.33.

4.1.2. Determination of the Diameter and Length of the Sieve Cylinder

The productivity of a machine is related to the diameter and inclination of the sieve cylinder [28]. The relationship between them satisfies Equation (3).

$$D={\displaystyle \frac{2}{h}}\times {\left({\displaystyle \frac{5Q}{3\rho \tan 2\alpha }}\right)}^{{\displaystyle \frac{2}{3}}}$$

(3)

In the formula, D is the diameter of the tumbler sieve, m; h is the thickness of the material in the sieve cylinder, m; ρ is the mixed density of larvae and insect sand, which is measured to be 0.255 t/m³; Q is the sieving efficiency of the tumbler sieve, which is taken to be 5 t/h in accordance with the demand for productivity; and α is the inclination angle of the sieve cylinder, °.

Based on the maximum length of the residual film in the material, the height of the spiral blades is determined as 100 mm [22]. The bulk particles have a filling flow effect, so the thickness of the material in the sieve cylinder is the height of the spiral blades, which is h: 0.1 m.

According to the empirical formula, the sieve cylinder length is calculated as follows.

$$L_1=KD$$

(4)

In the formula, L₁ is the theoretical length of the sieve cylinder circular hole section, m, and K is the spiral conveying coefficient, taking into account the structural stability of the value of the range of 3~5.

Assuming that the angle between gravity and centrifugal force when the material is lifted along the inside wall of the sieve cylinder is α, the effective sieving area S of the circular hole section of the sieve cylinder should satisfy Equation (5).

$$\left\{\begin{array}{l}S={\displaystyle \frac{D}{2}}\left({\alpha }_{\max }-{\alpha }_{\min }\right)L\\ S\ge {\displaystyle \frac{Q_s}{q_s}}\end{array}\right.$$

(5)

In the formula, α_min is the critical condition of the material rising for the material sliding friction angle of 45°; α_max is the material in the drum rising to the top with gravity and a centrifugal force angle of 90°; S is the effective screening area, m²; Q_s is the amount of material feeding into the system, kg/s; and q_s is the unit area of the sieve’s cylindrical holes section and its sieving capacity, kg/(s·m²).

According to the previous airflow angle analysis to set the tilt angle range 0~5° [22], substituting this into the formula (3) calculation obtains a sieve cylinder diameter D = 1.1 m.

With the combination of the machine operation index, substitution into Equation (4) obtains 3.3 m < L₁ < 5.5 m. According to the Agricultural Machinery Design Manual, the sieve capacity q_s per unit area of the circular hole section of the sieve cylinder is about 1.5~2.5 kg/(s·m²). Because of the high humidity of the insect sand, the sieve cylinder circular hole section unit area sieving capacity q_s is taken as 2 kg/(s·m²), and substituting it into Equation (5) can get the theoretical length of the sieve cylinder circular hole section L₁ ≥ 3.19 m.

In order to ensure that the insect sand is sieved out as completely as possible, the overall length L₁ of the circular hole section of the sieve cylinder is determined to be 4 m, taking into account the sieving effect and the stability of the machine. The side retaining ring provided at the end of the perforated section of the sieve cylinder blocks the larvae that are not sieved out in time from falling to the residual film outlet, meaning that the perforated section of the sieve cylinder is not provided with a spiral blade to allow it to slide inside the sieve cylinder. Through the preliminary pre-test, the length of the long circular hole section of the sieve cylinder, L₂, was set to 0.5 m, which meant that the overall length of the sieve cylinder, L, was 4.5 m.

4.1.3. Determination of the Rotational Speed of the Sieve Cylinder

The rotation speed of the sieve cylinder has a direct influence on the movement of the material and the state of force. In order to achieve effective sieving, the working condition of the sieve cylinder needs to achieve two modes of motion, which are rolling and throwing down, as shown in Figure 8. In the low-speed condition, the material mainly rolls and slides at the bottom of the sieve cylinder. As the rotational speed increases, the material gradually changes from the initial sliding state to the throwing state. When the rotational speed is further increased to high speed, the material will be close to the inside wall of the sieve surface, which presents a centrifugal state. It will generate inward slip as well as side throw when the material is in the state of being thrown down [29]. At this time, the material is thrown into the center of the sieve cylinder, and the area of the material subjected to wind increases, so that light impurities such as pieces of film can be separated with the best effect.

The sliding friction angle of insect sand is greater than that of larvae, so it is easier for insect sand to reach the throwing state compared to larvae. In order to ensure the activity of the larvae, this study analyzed the stresses on the insect sand when it was in a thrown state. Without considering the forces between the materials or between the materials and the spiral blades, we analyzed the force on the inside wall of the sieve cylinder. As shown in Figure 9, we set the tangent direction of the material along the sieve cylinder as the x-axis and the normal direction as the y-axis.

When the material moves from the bottom of the sieve cylinder against the wall to below the center axis,

$$\left\{\begin{array}{c}N=F+G\cos \delta \\ f=G\sin \delta \end{array}\right.$$

(6)

$$\left\{\begin{array}{c}F={\displaystyle \frac{m{v}^2}{R}}\\ G=mg\\ f=\mu \left(F+\cos \delta \right)\\ v={\displaystyle \frac{\pi }{30}}Rn\end{array}\right.$$

(7)

In the formula, m is the quality of the material, kg; R is the radius of the cylinder, R = D/2, m; g is the acceleration of gravity, 9.8 N/kg; μ is the friction coefficient of the contact between the material and the inside wall of the sieve cylinder, generally 0.3 to 0.6, take 0.5 for the for the non-smooth surface of the sieve cylinder; and n is the sieve cylinder rotational speed, r/min.

When the material is below the center axis (δ ∈ (0, π/2)), the rotational speed at which sliding of the material occurs is calculated as follows.

$$n_1={\displaystyle \frac{30}{\pi }}\sqrt{{\displaystyle \frac{g\left(\sin \delta -\mu \cos \delta \right)}{\mu R}}}$$

(8)

In the formula, n₁ is the rotational speed of the material when the sliding motion occurs, r/min.

The force on the material when it crosses the center axis and falls at the highest point satisfies Equation (9).

$$\left\{\begin{array}{c}F=N+G\cos \delta \\ f=G\cos \delta \end{array}\right.$$

(9)

$$f=\mu \left(F-\sin \delta \right)$$

(10)

It can be calculated that when the material is above the center axis (δ ∈ (0, π/2)), the rotational speed at which the material undergoes ejection is calculated according to Equation (11).

$$n_2={\displaystyle \frac{30}{\pi }}\sqrt{{\displaystyle \frac{g\sin \delta }{R}}}$$

(11)

When the material moves to the upper apex of the upper inside wall of the sieve cylinder, the rotational speed is calculated according to Equation (12).

$$n_3={\displaystyle \frac{30}{\pi }}\sqrt{{\displaystyle \frac{g}{R}}}$$

(12)

The following conditions shall be met when the sieve cylinder reaches the throw-off condition at high rotational speed.

$$mR{\omega }^2-mg\le 0$$

(13)

In the formula, ω = 2πn.

The minimum rotational speed of the sieve cylinder shall satisfy Equation (14).

$$mR{\omega }^2-mg\mu \ge 0$$

(14)

Then the rotational speed of the sieve cylinder is calculated according to Equation (15).

$${\displaystyle \frac{23}{\sqrt{R}}}\le n\le {\displaystyle \frac{30}{\sqrt{R}}}$$

(15)

Substituting the structural parameters of the sieve cylinder, the rotational speed range of the sieve cylinder is 31.01 r/min to 40.45 r/min. Considering the centripetal adsorption effect produced by airflow cohesion inside the cylinder, the rotational speed range is enlarged by ±50% and rounded up, and the final rotational speed of the cylinder is designed to be 15 r/min to 60 r/min.

4.1.4. Determination of Spiral Blade Structure and Parameters

As shown in Figure 10. When unscreened material enters from the feeding port, the fragments of residual film are blown out of the sieve cylinder under the effect of airflow, the larvae and insect sand are moved along the direction of the sieve cylinder axis under the effect of the spiral blade. During the moving process, the insect sand is dropped into the gibbet through the circular hole section, and the larvae are discharged from the long circular hole section.

Assuming that the angle of rise in the spiral blades is τ, if the material is made to move in the direction of the axis of the sieve cylinder, it needs to be calculated according to Equation (16) so as to ensure that the power is greater than the resistance in the direction of the axis.

$$F_N\cos \tau \ge F_f\sin \tau +f_o\sin \left({\displaystyle \frac{\pi }{2}}-\tau -\sigma \right)$$

(16)

In the formula, F_N is the normal thrust of the spiral blade on the material, N; σ is the sliding friction angle, °; and f_o is the friction force of the spiral blade on the material, N.

$$\left\{\begin{array}{l}{F}_N\cos \tau >F_f\sin \tau \\ F_f={\mu }_1{F}_N=F_N\tan \sigma \end{array}\right.$$

(17)

$$\cot \tau >\tan \sigma$$

(18)

$$\tau <{\displaystyle \frac{\pi }{2}}-\sigma$$

(19)

If the insect sand is transported in the direction of the sieve cylinder axis, the axial partial velocity is >0, which needs to satisfy Equation (20).

$$\tan \tau <\tan \left({\displaystyle \frac{\pi }{2}}-\sigma \right)$$

(20)

$$S_x=K_{x}D$$

(21)

In the formula, K_x is the spiral blade conveying coefficient, which is taken as 0.8 to 2 [27,29,30].

Since the spiral blades are welded to the inner wall of the sieve cylinder, the outer diameter of the spiral blades D is equal to the diameter of the sieve cylinder, 1.1 m. To improve the effect of material turning and mixing, double-headed spiral blades are used in the sieve cylinder, and the rising angle of the spiral blades, τ = 50°, is set according to the test of the sliding friction angle of the insect sand and the larvae. In this study, double-headed spiral blades were used, and the pitch of the blades was 1.8 m.

4.2. Kinematic Analysis of Secondary Separation Process of Larvae and Residual Film

Once the insect sand separation process in the front end of the circular sieve hole section has occurred, if the suspended velocity is relatively small, membrane will drift from the center of the sieve cylinder to the semi-open mesh box, and if the suspended velocity is larger, larvae will move through the sieve cylinder with the spiral blade movement to the end of the sieve cylinder at the long hole, aggregated into a cluster or near the wall. Small pieces of membrane will enter from the long hole with the larvae down through the sieve, for the rate of larvae in the film content has an impact. In order to improve the separation ratio of residual film, an axial flow membrane separation part is arranged at the larvae drop point. The larvae are guided and slid down on the inclined surface, and the axial flow fan blows the membrane sheets falling with the larvae into the membrane box.

According to the separation suspension velocity test, it was known that there were significant differences in suspension velocity, density, and quality between the larvae and the fragments of the residual film. When subjected to the trailing force of the working airflow, the two have different motion trajectories [31], as shown in Figure 11.

The sieved materials (larvae and residual membrane) are subjected to airflow hydraulic and gravitational forces after descending, as shown in Figure 12.

According to Equation (22), a force analysis was carried out on the sieved materials falling through the circular sieve holes.

$$\left\{\begin{array}{c}{F}_f=k\rho S_w{V}_f^2\\ G_c=m_{w}g\end{array}\right.$$

(22)

In the formula, k is the coefficient of resistance of the larvae in the air; ρ is the density of the materials, kg/m³; S_w is the area of the airflow on the sieved materials, m²; and m_w is the weight of the sieved materials, kg.

The airflow trailing force is decomposed to obtain the combined force F_x in the horizontal direction and the combined force F_y in the vertical direction, and then the acceleration a_x in the horizontal direction and the acceleration ay in the vertical direction can be calculated by Equation (23).

$$\left\{\begin{array}{c}{F}_y=G_c-F_f\sin \alpha \\ F_x=F_f\cos \alpha \\ a_x={\displaystyle \frac{G_c-F_f\sin \alpha }{m}}\\ a_y={\displaystyle \frac{F_f\cos \alpha }{m}}\end{array}\right.$$

(23)

From Equation (23), the falling time t, horizontal displacement l_x, and vertical displacement l_y of the material through the sieve are obtained.

$$\left\{\begin{array}{c}t=\sqrt{{\displaystyle \frac{2h_c}{a_y}}}\\ l_x={\displaystyle \frac{F_f\cos \alpha }{m{a}_y}}\\ l_y=h_c\end{array}\right.$$

(24)

In the formula, h_c is the distance from the bottom of the sieve cylinder to the deflector separator plate, m.

From Equation (24), Equation (25) is obtained.

$$l_x={\displaystyle \frac{k\rho S{v}^2\cos \alpha }{mg-k\rho S{v}^2\sin \alpha }}$$

(25)

From the above equations, it can be seen that the horizontal displacement of the material through the sieve is affected by the area of action, the working airflow velocity, the angle of action of the airflow, and the quality of the material. Under the same airflow conditions, the horizontal displacement of the larvae was smaller than that of the residual film, and the drop height of the larvae in the vertical direction was smaller due to the higher suspension velocity of the larvae than that of the film debris (Figure 11). In order to enhance the separation effect of the ground film, this paper designed a front low and back high deflector separator plate, with its face inclination angle set at 50° based on the larval sliding friction angle.

4.3. Design of Insect-Sand-Conveying Winch

With a production demand of 5 t/h, in order to ensure delivery efficiency, the basic conveying capacity of insect sand is determined to be about 4.39 t/h based on the analysis of the material composition percentage. Due to the uniform shape of the insect sand and the fact that it does not require crushing, we decided to use the upper open screw conveying structure as the insect-sand-conveying winch. As shown in Figure 13, it is mainly composed of a spiral blade, spiral shaft, bottom shell, and other components. The spiral blades are designed as a single-ended solid type and are welded to the spiral shaft in an equal-pitch arrangement. The spiral shaft is made of 45# steel, with a diameter of 40 mm at the end of the shaft. It is driven by the rotation of the motor that drives the rotation of the spiral blade, so as to realize the continuous and efficient transportation of the insect sand to the front end of the machine.

As can be seen from the actual working characteristics, the dispersion of insect sand is relatively uniform when it falls through the sieve cylinder, the demand for conveying speed is not high, and the delivery of insect sand is in a non-full-filling state. When working at low speed, the blocking material flow is not significant to the movement. In order to prevent the insect sand from jumping and tumbling, stirring the main body of the conveyor, the centripetal force on the insect sand and its own gravity should meet the formula (26) [32].

$$m_s{\left({\displaystyle \frac{2\pi n_s}{60}}\right)}^2{R}_s<m_{s}g$$

(26)

By reducing Equations (26) and (27),

$${\displaystyle \frac{\pi n_{s\max }}{30}}\le \sqrt{g{R}_s}$$

(27)

The introduction of the material synthesis characteristic coefficient K_s (0 < K_s < 1) gives Equation (28).

$$n_{s\max }={\displaystyle \frac{30K_s}{\pi }}\sqrt{{\displaystyle \frac{g}{R_s}}}$$

(28)

Suppose that $A={\displaystyle \frac{30K_s\sqrt{2g}}{\pi }}$. The maximum speed of the winch can be calculated from Equation (29).

$$n_{s\max }={\displaystyle \frac{A}{\sqrt{D_s}}}$$

(29)

In Equations (26)–(29), R_s = D_s/2; D_s is the spiral outer diameter (nominal diameter of the winch), mm; m_s is the quality of insect sand, kg; n_s is the rotational speed of the winch, r/min; and K_s is the comprehensive characteristic coefficient of the materials.

Spiral speed should be based on the spiral’s outer diameter and the characteristics of the material, under the premise of meeting the requirements of conveying capacity. The spiral speed should not be too high [33].

$$47D_{s}2S_1{n}_s\psi C\gamma \ge Q_s$$

(30)

In the formula, S₁ = πD_s·tan α_s and S₁ = K_w·D_s.

By reducing Equations (30) and (31),

$$D_s>\sqrt[2.5]{{\displaystyle \frac{1}{47K_{w}A}}\cdot {\displaystyle \frac{Q_s}{\psi C\gamma }}}$$

(31)

$K_s=\sqrt[2.5]{{\displaystyle \frac{1}{47K_{w}A}}}$. By reducing Equations (31) and (32),

$$D_s>K_s\sqrt[2.5]{{\displaystyle \frac{Q_s}{\psi C\gamma }}}$$

(32)

In Equations (30)–(32), S₁ is the pitch of the winch, m; Q_s is the actual conveying capacity, t/h; ψ₁ is the filling rate of the insect sand material, taking 0.2; c is the inclination coefficient, taking 1 when conveying horizontally; and γ is the stacking density of the material to be conveyed, t/m³.

Then the stringer pitch and helical inner diameter need to satisfy Equation (33).

$$S_1<{\displaystyle \frac{\pi d}{{\mu }_s}}$$

(33)

In the formula, d is the inner diameter of the gibbet, which is the inner diameter of the spiral, m, and μ_s is the friction coefficient between the insect sand and the spiral surface of the gibbet, taken as 0.4.

Querying the material comprehensive characteristic coefficient, it can be seen that K_s is 0.0565 and A is 35. The measured bulk density of insect sand is about 328~360 kg/m³, and the calculation gives D_s > 0.35 m. We checked JB/T7679-2019 stranding machinery industry standards to determine that the spiral nominal diameter D_s is 0.4 m and pitch S₁ is 0.355 m. Substituting the above parameters into Equation (29), the maximum rotational speed of the winch n_s ≤ 55 r/min can be calculated.

5. Experiments and Analyses

In order to test the operating effect of the pneumatic tumbler-sieve-type white star golden beetle larvae transformation mixture separator, the project team conducted a material sieving test in November 2024 at the insect industrialization research base in Manas County, Xinjiang, as shown in Figure 14.

5.1. Single-Factor Test

In order to determine the optimal working range of each factor level of the three-factor three-level response surface test, the sieve cylinder rotational speed, sieve cylinder inclination angle, inlet wind speed for a single-factor test, and the residual film containing impurity rate Y₁ and larvae deactivation rate Y₂ as an evaluation index [34,35], we used the calculation formulas shown in Equations (34) and (35). Three samples were taken for each test to measure and calculate the mean value in order to derive the law of influence of each factor on the sieving effect. The separated residual film and larvae were sampled using a 30*40*15 cm transit box, which was not directly compressed during the sampling process and was not less than half full. Among them, the larval inactivation phenomenon could not be directly distinguished visually, and the separated larvae were put into the non-film humus substrate for 10 days. In addition to direct damage, the larvae with invisible damage would die naturally and undergo browning and shriveling (as shown in Figure 15), and the number of surviving larvae in the sampled larvae was counted to calculate the larval inactivation rate.

$$Y_1={\displaystyle \frac{M_1}{M_2}}\times 100\%$$

(34)

$$Y_2={\displaystyle \frac{M_3}{M_4}}\times 100\%$$

(35)

In the formulas, M₁ is the quality of impurities collected in the lower open net box, kg; M₂ is the total mass of material in the lower open net box, kg; M₃ is the number of inactivated larvae isolated; and M₄ is the total number of larvae isolated.

According to the design parameters, the test ranges of sieve cylinder rotation speed, sieve cylinder inclination angle, and inlet wind speed were 15 r/min to 55 r/min, −6° to 6°, and 2 m/s to 8 m/s, respectively, and the test range was divided by the equidistant splitting method to test the influence of the three factors on the sieving effect, respectively. The average of two indicators was recorded.

5.1.1. Influence of Sieve Cylinder Rotational Speed on Sieving Effect

Under normal working conditions, the rotational speed of the sieve cylinder is crucial to the sieving performance. Too low a rotational speed will reduce the sieving efficiency, prolong the separation time of insect sand, and increase the energy consumption; too high a rotational speed will lead to an increase in the material transportation distance and throwing speed, affecting the sieving quality. In order to explore the influence of rotational speed, we conducted a one-factor test to adjust the rotational speed of the sieve cylinder under the conditions of a sieve cylinder inclination angle of 0° and an inlet wind speed of 5 m/s, and the results are shown in Figure 16.

Figure 16 shows that the rotational speed of the sieve cylinders caused significant changes in the residual film inclusion rate and larval inactivation rate. Both of them decreased and then increased with the increase in rotational speed, but the larval inactivation rate slightly decreased at high rotational speed. At 25 r/min, both indicators reached their minimum values, which were 8.8% for residual film impurity rate and 3.3% for larval inactivation rate, respectively.

5.1.2. Influence of Sieve Cylinder Inclination Angle on Sieving Effect

If the sieve cylinder angle of inclination at the front end is lower than the back end it is defined as positive, and vice versa is negative. In the sieve cylinder, the material is drifted by the trailing force of the airflow, and the inclination of the sieve cylinder directly affects the landing point of the material movement. The inclination angle is too large to make the material horizontally close to the front end, reducing the sieving efficiency of the white star golden beetle larvae and increasing the frequency of collision between the larvae and the wall of the sieve cylinder. Under the condition of a sieve cylinder rotational speed of 35 r/min and an inlet wind speed of 5 m/s, we conducted a one-factor test for the sieve cylinder inclination angle, and the results are shown in Figure 17.

Figure 17 shows that when the sieve cylinder inclination angle increased, the overall trends of residual film impurity rate and larval inactivation rate both decreased and then increased. Among them, the residual film impurity rate fluctuated greatly, but the change was not significant in the range of a 0° to 3° inclination angle; the lowest impurity rate appeared at a −3° inclination angle, which was 13.5%. The lowest larval inactivation rate occurred at 0°, which was 3.3%.

5.1.3. Influence of Inlet Air Velocity on Sieving Effect

In the sieving process, the front fan provides airflow traction to blow the film away from the sieve cylinder, and the insect sand and larvae are blown to the back side of the sieve cylinder for sieving. If the wind speed is too high, the insect sand will be blown out together with the residual film; if the wind speed is too low, the airflow will dissipate and attenuate the residual film, which will accumulate in the sieve cylinder and affect the sieving efficiency. In order to investigate the effect of wind speed, a one-factor test was carried out under the conditions of a sieve cylinder speed of 35 r/min and inclination angle of 0°, and the results are shown in Figure 18.

Figure 18 shows that with increasing inlet wind speed, the residual film inclusion rate showed a double trough, reaching a minimum of 12.3% at an inlet wind speed of 6.5 m/s. The overall larval inactivation rate continued to decrease with increasing rotational speed, and was lowest at the inlet wind speed of 8.0 m/s, at 3.4%.

5.2. Test Program

According to the results of the one-factor tests, the sieve cylinder speed test range was set to 15 r/min~35 r/min, the sieve cylinder inclination test range was set to −3°~3°, and the inlet wind speed was adjusted to 4 m/s~7 m/s. In order to determine the preferred parameter combinations, the impact of the sieve cylinder rotation speed, sieve cylinder inclination, and inlet wind speed on the sieving effect of the mixture separator, residual film impurity rate Y₁ and the larval inactivation rate Y₂ were investigated by applying the Design-Expert three-factor central composite response surface test [36,37]. The test factor code is shown in

Table 2. Test factors and codes.

Codes	Rotational Speed of Sieve Drum X1/(r/min)	Inclination of the Sieve Drum X2/(°)	Air Speed at the Inlet X3/(m/s)
−1	15	−3	4.0
0	25	0	5.5
1	35	3	7.0

. The same batch of materials was used for the experimental tests. The test program and the results are shown in

Table 3. Test program and results.

Test Number	X1	X2	X3	Rate of Residual Film Impurity Y1/%	Rate of Larval Inactivation Y2/%
1	0	1	1	13.74	3.85
2	−1	0	1	12.95	4.55
3	−1	0	−1	12.33	4.3
4	1	−1	0	10.58	5.5
5	−1	−1	0	11.75	4.46
6	0	0	0	8.7	3.25
7	1	0	−1	11.05	5.88
8	0	0	0	8.84	3.23
9	0	0	0	8.68	3.26
10	−1	1	0	11.68	4.75
11	1	1	0	11.88	5.86
12	1	0	1	14.15	5.22
13	0	−1	1	13.72	3.18
14	0	−1	−1	11.56	3.65
15	0	1	−1	12.76	3.56

.

5.3. Variance Analysis

The analysis of variance and significance test of the experimental program and results were carried out using Design-Expert (version number: 8.0.6), and the results are shown in

Table 4. Regression model analysis of variance.

Index	Source of Variance	Square Sum	Degrees of Freedom	Mean Square	F	p
Rate of residual film impurity Y1/%	model	45.12	9	5.01	160.39	<0.0001 **
	X1	0.14	1	0.14	4.41	0.0898
	X2	0.75	1	0.75	24.01	0.0045 **
	X3	5.88	1	5.88	188.21	<0.0001 **
	X1X2	0.47	1	0.47	15.01	0.0117 *
	X1X3	1.54	1	1.54	49.20	0.0009 **
	X2X3	0.35	1	0.35	11.14	0.0206 *
	X12	5.35	1	5.35	171.18	<0.0001 **
	X22	8.63	1	8.63	276.09	<0.0001 **
	X32	26.45	1	26.45	846.12	<0.0001 **
	residual error	0.16	5	0.031
	lack of fit	0.14	3	0.047	6.19	0.1423
	inaccuracies	0.015	2	7.600 × 10−3
	amount	45.27	14
Rate of larval inactivation Y2/%	model	13.25	9	1.47	823.49	<0.0001 **
	X1	2.42	1	2.42	1353.22	<0.0001 **
	X2	0.19	1	0.19	105.75	0.0001 **
	X3	0.044	1	0.044	24.33	0.0043 **
	X1X2	1.225 × 10−3	1	1.225 × 10−3	0.68	0.4456
	X1X3	0.21	1	0.21	115.76	0.0001 **
	X2X3	0.14	1	0.14	80.75	0.0003 **
	X12	10.19	1	10.19	5700.82	<0.0001 **
	X22	0.20	1	0.20	113.21	0.0001 **
	X32	0.023	1	0.023	12.94	0.0156 *
	residual error	8.942 × 10−3	5	1.788 × 10−3
	lack of fit	8.475 × 10−3	3	2.825 × 10−3	12.11	0.0773
	inaccuracies	4.667 × 10−4	2	2.333 × 10−4
	amount	13.26	14

Note: * indicates significant effect (0.01 < p < 0.05); ** indicates highly significant effect (p < 0.01).

. As can be seen from Table 4, except for the sieve cylinder rotational speed, which had no significant effect on the residual film impurity rate, the other test factors had significant effects on the residual film impurity rate Y₁ and larval inactivation rate Y₂, and the order of the significance of the effects of the test factors on the residual film impurity rate was inlet wind speed, sieve cylinder inclination, and sieve cylinder rotational speed; the order of the significance of the effects on the larval inactivation rate was sieve cylinder rotational speed, sieve cylinder inclination, and inlet wind speed. The interactions between sieve cylinder speed and sieve cylinder inclination and sieve cylinder inclination and inlet wind speed had highly significant effects on the residual film impurity rate Y₁, and the interaction of sieve cylinder speed with inlet wind speed, sieve cylinder inclination, and sieve cylinder wind speed had a highly significant effect on the larval inactivation rate Y₂.

By regression analysis of the test results and elimination of insignificant terms, the regression equations of the effects of sieve cylinder rotational speed, sieve cylinder inclination angle, and inlet wind speed on the residual film impurity rate Y₁ and larval inactivation rate Y₂ were obtained, as shown below.

$$Y_1=8.74+0.31X_2+0.86X_3+0.34X_1{X}_2+0.63X_1{X}_3-0.29X_2{X}_3+1.2X_1^2+1.53X_2^2+2.68X_3^2$$

(36)

$$Y_1=3.25+0.55X_1+0.15X_2-0.074X_3-0.23X_1{X}_3+0.19X_2{X}_3+1.66X_1^2+0.23X_2^2+0.079X_3^2$$

(37)

5.4. Response Surface Analysis

In order to understand the effect of the interaction of the test factors on the residual film content and insect sand content, Design-Expert was applied to plot the residual film content and larval inactivation rate response surface plots, respectively, as shown in Figure 19.

According to the response surfaces in Figure 19a–c, the effects of sieve cylinder rotational speed, sieve cylinder inclination angle, and inlet air velocity on the residual film impurity rate can be observed. Specifically, as the sieve cylinder rotational speed increases, the residual film impurity rate shows a trend of decreasing and then increasing, and reaches the minimum value at about 25 r/min, which indicates that the appropriate sieve cylinder rotational speed helps to reduce the impurity content in the residual film. The increase in the screening drum rotational speed makes the falling tendency of the materials in the process of turning biased towards the central axis, and the materials fall evenly and separate more thoroughly. However, if the speed is too large, it causes an increase in centrifugal force, thus making the material and the inner wall surface contact degree higher, prompting the material to press itself to the wall and prolong the insect sand movement distance, increasing the risk of drift to a certain extent and increasing the residual film impurity content. Meanwhile, when the sieve cylinder inclination angle increased and the inlet air velocity increased, the residual film impurity rate also showed a trend of increasing and then decreasing. It is worth noting that the effect of inlet air velocity on the residual film impurity content is more significant than that of sieve cylinder inclination. Under the conditions of −0.3° sieve cylinder inclination angle and 5.2 m/s inlet wind speed, the residual film impurity rate reached the minimum value.

Similarly, observing Figure 19d,e, the effects of inlet wind speed, sieve cylinder rotational speed, and sieve cylinder inclination on larval inactivation rate can be obtained. With the increase in inlet wind speed, the larval inactivation rate shows a small attenuation, but the overall difference is not significant, and it reaches the minimum at an inlet wind speed of about 7.0 m/s, which indicates that the effect of inlet wind speed on the larval inactivation rate is relatively small. However, with the increase in sieve cylinder speed, the larval inactivation rate showed a significant trend of decreasing and then increasing, which suggests that we need to choose the appropriate sieve cylinder speed to minimize the larval inactivation in practical operation. The distance over which the larvae fall during rotation and the position of collision are closely related to the rotational speed. When the rotational speed is smaller, the collision rate between the components of the materials increases, and the collision rate between the components and the inner wall of the sieve drum also increases. When the rotational speed increases, the materials present a pouring and throwing state, and the larvae drift toward the exit under the action of airflow, which can reduce the number of collisions. Meanwhile, the larval inactivation rate also showed a tendency of decreasing and then increasing with the increase in sieve cylinder inclination. Although this change may not be as significant as the effect of sieve cylinder rotation speed, it still deserves our attention.

5.5. Optimization of Parameters

In order to explore the optimal working parameters of the pneumatic tumbler-sieve-type white star beetle larvae conversion mixture separator, an optimization module was used to find the optimal residual film impurity rate and larvae rate [38]. Its optimization objective was to seek the minimum value of the test indicators, the range of optimization was the minimum as well as the maximum value of the test factors, and the optimization model was as shown in Equation (38). The two proposed indicators have the same effect on the sieving effect (++++), and the optimal parameter combination of the test factors are as follows: a sieve cylinder rotational speed of 24 r/min, sieve cylinder inclination angle of −0.43°, and inlet wind speed of 5.32 m/s. Under these conditions, we achieved a residual film impurity rate and larvae inactivation rate of 8.7% and 3.2%, respectively.

$$\left\{\begin{array}{l}\min Y_1,\min Y_2\\ 15\le X_1\le 35 \mathrm{r}/\min \\ -3°\le X_2\le 3°\\ 4 \mathrm{m}/\mathrm{s}\le X_3\le 7 \mathrm{m}/\mathrm{s}\end{array}\right.$$

(38)

5.6. Experimental Verification

In order to verify the reliability of the optimization results, the project team carried out experimental verification based on the optimized test parameters. In order to facilitate the operation, the material sieving test used the optimal combination of parameters: a sieve cylinder speed 24 r/min, sieve cylinder inclination angle −0.4°, and inlet wind speed 5.3 m/s. We started the separator through the control cabinet and used frequency converter adjustment to change the actual measurement of the sieve cylinder speed and inlet wind speed up to the optimized the frequency values of the parameters. We then shutdown and recorded the test so that the components could achieve the predetermined frequency to carry out the validation test. In order to eliminate random errors, we conducted the test five times in order to take the average value as the actual test results. Test verification results show that the residual film containing impurity rate was 8.74%, the larval inactivation rate was 3.18%, and relative error between the theoretical values of the two indicators and the test values was less than 5%. Therefore, the optimization results are reliable.

6. Conclusions

(1) Aiming at the demand for the separation of materials after the transformation of residual film mixtures by the protaetia brevitarsis larvae, a pneumatic drum-sieve-type separator for transforming mixtures of protaetia brevitarsis larvae was designed, and through theoretical analysis and calculations, the main structure and working parameters of its key components were determined.

(2) With rotational speed of the sieve cylinder, inclination angle of the sieve cylinder, and air speed at the inlet as the test factors, and residual film impurity rate and larval inactivation rate as the evaluation indexes, single-factor experiments and a quadratic regression response surface experiment containing three factors and three levels were carried out. A regression model was developed between the two indicators and the significant factors, and it was used for parameter optimization. The experimental results showed that when the rotational speed of the sieve cylinder was 24 r/min, the inclination angle of the sieve cylinder was −0.43°, and air speed at the inlet was 5.32 m/s, the residual film impurity rate and larval inactivation rate were the lowest, which were 8.7% and 3.2%, respectively.

(3) To optimize the round value for the verification test, the experimental results showed that the average values of residual film impurity rate and larval inactivation rate obtained from the material sieving test under these parameters were 8.74% and 3.18%, with the relative errors of the theoretically optimized values being less than 5%. The design of the machine meant that the operating performance met production needs.

(4) In this study, efficient separation and collection of protacia brevitarsis larvae (proteins), insect sand (fertilizers), and residual film were achieved by the integrated technology of airflow sorting and drum sieving. The low-loss larval living body separation technology provides a foundation for large-scale breeding and promotes the transformation of residual film pollutants into green resources. In the future, the research can expand the technology to treat different crop wastes and livestock manure, while the structure of the machine can be optimized to adapt to diversified scenarios. Attention needs to be paid to the potential limitations of the scalability and long-term operational performance of the developed machine, such as the effect of differences in material properties on separation effectiveness, wear and tear of key components, and maintenance costs, to validate the suitability and effectiveness of the model in a wider range of agricultural solid waste resource utilization applications and to assist in green development.