Recycling system for secondary application of fine sand

Abstract

The invention provides a recycling system for secondary application of fine sand. The recycling system comprises a single-layer screening unit, a multi-layer screening unit, a cleaning and dewatering unit and a flotation desliming unit which are sequentially arranged according to a recycling path. A vibrating screen is arranged in the single-layer screening unit, a plurality of groups of adjustable vibrators are arranged on the vibrating screen, the mounting positions of the vibrators are controlled by a control chip to be adjusted, fine sand components are classified according to a particle size-component two-dimensional classification algorithm, and frequency and amplitude are adjusted according to a classification result; an online particle size analyzer and a mineral component detection probe are arranged at the feeding position of the vibrating screen, and materials do forward or non-return screening movement on the screen surface; the classification data are imported into the cleaning and dewatering unit; a circular vibrating screen is arranged in the multi-layer screening unit, a plurality of circular vibrating screen frame screening faces are arranged on the circular vibrating screen, and stainless steel screen pieces with different hole diameters are installed on the circular vibrating screen frame screening faces.

Description

Technical Field

[0001] The present invention belongs to the field of recycling and treatment, and particularly relates to a recycling and treatment system for secondary application of fine sand. Background Art

[0002] In the fields of construction, mining and industrial manufacturing, fine sand, as an important basic material, is widely used in multiple scenarios such as concrete preparation, casting process, filling projects, etc. However, the waste fine sand generated during the production process (such as the residual sand from concrete mixing, foundry waste sand, mine tailings, etc.) is difficult to be directly reused due to problems such as containing impurities, uneven particle distribution or chemical contamination. Traditional treatment methods are mostly landfill or simple stacking, which not only occupy land resources, but also may cause environmental problems such as dust pollution and groundwater seepage. With the promotion of the concepts of resource recycling and green production, the secondary application of fine sand has gradually become the focus of industry attention, but the existing recycling and treatment technologies still have significant defects.

[0003] Traditional screening equipment has low processing efficiency for fine sand. Especially when dealing with fine sand with a higher moisture content, the sieve is easily blocked, resulting in a decrease in separation accuracy. It is unable to effectively distinguish fine sand particles with similar particle sizes from impurities (such as clay and organic debris), and the purity of the recycled fine sand is insufficient, making it difficult to meet the requirements of high-value-added applications (such as precision casting or high-strength concrete).

[0004] Existing washing processes mostly use multi-stage water washing tanks or spiral sand washers. Although they can remove some surface pollutants, the water consumption is huge, consuming 3 - 5 cubic meters of water per ton of fine sand washing. Moreover, the treatment cost of the muddy wastewater generated is high. If not equipped with an efficient flocculation and precipitation system, it is easy to cause secondary pollution. In addition, the dehydration link generally relies on vibrating screens or centrifuges, and the dehydration effect on extremely fine sand with a particle size less than 0.075mm is poor, and the moisture content of the finished product is often higher than 15%, resulting in an increase in transportation costs and easy caking during storage, seriously affecting the reuse performance. Some technologies attempt to introduce thermal drying, but the energy consumption is extremely high (consuming 50 - 80 kWh of electric energy per ton of fine sand drying), and the economy is poor, making it difficult to be applied on a large scale. Furthermore, for chemically contaminated fine sand (such as phenolic residues in foundry resin sand and heavy metal attachment in mine sand), existing physical separation technologies cannot effectively strip the pollutants, and the chemical leaching method has a risk of drug residue, and the safety of the treated fine sand cannot be guaranteed, restricting its application in environmentally sensitive fields.

[0005] The existing system has a low degree of automation. Each processing unit (crushing, screening, washing, dewatering) operates independently, lacking intelligent regulation and data linkage, and it is difficult to dynamically adapt to fluctuations in raw material properties (such as changes in moisture content and impurity types). Manual intervention is often required to adjust parameters, resulting in unstable processing efficiency and large fluctuations in energy consumption. Especially in small-scale decentralized application scenarios (such as on-site treatment at construction sites), the problems of large floor area, poor mobility, and low integration of traditional equipment are more prominent, and they cannot meet the flexible and rapid recycling needs. These technical bottlenecks have severely restricted the popularization of fine sand resource utilization. Summary of the Invention

[0006] The present invention provides a recycling and processing system for secondary application of fine sand. This system solves the problems of low screening accuracy, rigid parameter adjustment, and serious resource waste in traditional fine sand recycling. Through the collaborative optimization of multi-stage screening and dynamic algorithms, it realizes the accurate classification of fine sand in terms of particle size and composition in two dimensions, the real-time adaptation of cleaning and dewatering parameters, and the intelligent control of the flotation and de-sludging process, significantly improving the secondary utilization rate and recycling quality of fine sand.

[0007] The technical solution of the present invention is realized as follows: A recycling and processing system for secondary application of fine sand includes a single-layer screening unit, a multi-layer screening unit, a cleaning and dewatering unit, and a flotation and de-sludging unit arranged in sequence according to the recycling path;

[0008] The single-layer screening unit is internally provided with a vibrating screen. The vibrating screen is provided with adjustable multiple groups of vibrators, and the installation positions of the vibrators are controlled and adjusted by a control chip. The fine sand composition is classified according to the particle size-composition two-dimensional classification algorithm, and the frequency and amplitude are adjusted according to the classification results; An on-line particle size analyzer and a mineral composition detection probe are provided at the feeding place of the vibrating screen, and the material makes a forward or reverse screening movement on the screen surface; And the classification data is imported into the cleaning and dewatering unit.

[0009] The multi-layer screening unit is internally provided with a circular vibrating screen. The circular vibrating screen is provided with multiple circular vibrating screen frame surfaces. Among them, stainless steel screen mesh pieces with different pore diameters are installed on the circular vibrating screen frame surfaces. Adjustable multiple groups of vibrators are provided on the screen surfaces. An on-line particle size analyzer and a mineral composition detection probe are provided at the feeding place of the circular vibrating screen. Multiple screen holes and screen mesh pieces are provided on the screen surface, and a forward or reverse screening movement is made on the screen mesh.

[0010] The cleaning and dewatering unit is a vibrating sand washer. The vibrating sand washer is provided with adjustable multiple groups of vibrators, and the installation positions of the vibrators are adjusted in real time according to the classification data.

[0011] The flotation desludging unit is a fine sand flotation machine, which is provided with fine sand and water, and is filled with flotation agent. The flotation machine is provided with a dosing device, which automatically controls the dosing module according to the particle size analysis result of the online particle size analyzer, and controls the flotation desludging path according to the result of the online mineral composition analysis probe; the flotation time, flushing intensity and flotation concentration are dynamically adjusted according to the mineral composition and content of the fine sand.

[0012] The innovative design of the single-layer screening unit is a dual-dimensional classification algorithm and dynamic adjustment: the existing technology mostly uses single particle size screening, and this system pioneered the "particle size-composition dual-dimensional classification algorithm". Through the online particle size analyzer and the mineral composition detection probe, the material properties are obtained in real time, and the control chip is combined to dynamically adjust the frequency / amplitude of the vibrator (such as 50-200Hz frequency range, 1-5mm amplitude gradient), to achieve directional screening of fine sands of different components (such as quartz sand and clay separation). Traditional vibrating screens only move in one direction. This system uses a programmable vibrator to achieve material forward / reverse alternating screening (such as switching direction every 5 minutes), effectively solving the problem of screen hole blockage.

[0013] The built-in circular vibrating screen in the multi-layer screening unit adopts a stainless steel screen with a gradient aperture (such as a three-level combination of 0.5mm / 1mm / 2mm), and the centrifugal stratification effect of the circular vibrating screen frame can achieve a particle size classification accuracy of ±0.1mm, which is far higher than the traditional linear screen (±0.3mm). The existing technology mostly uses a single aperture screen, which cannot adapt to complex particle size distribution. Each layer of the screen is independently equipped with an adjustable vibrator, which generates a three-dimensional vibration field through phase difference control (such as 0°-180° adjustable). Based on the classification data of the single-layer screening unit (such as when the clay content is greater than 20%), the high-frequency dehydration mode is automatically switched to dynamically adjust the vibration energy consumption according to the moisture content of the material (such as reducing the frequency to 60Hz when the moisture content is 15%).

[0014] Compared with the existing technology, this recovery and processing system for secondary application of fine sand has obvious advantages in the accuracy and efficiency of fine sand screening, cleaning and flotation processing. Traditional fine sand recovery systems often rely on a single screening method and a fixed processing flow, resulting in inaccurate classification of fine sand components and low recovery efficiency. In traditional systems, the screening process usually uses a vibrating screen with a fixed frequency and amplitude, which cannot be dynamically adjusted according to the different particle sizes and components of the fine sand, which easily causes the fine sand components to mix, affecting the subsequent cleaning and flotation effects. However, this system, by setting a single-layer screening unit and a multi-layer screening unit, combined with an adjustable multi-group vibrator, can classify the fine sand components according to the particle size-component dual-dimensional classification algorithm, and adjust the frequency and amplitude of the vibrator in real time to adapt to the characteristics of different fine sands, effectively improving the recovery accuracy of fine sand.

[0015] Specifically, in the design of the single-layer screening unit, the combination of the built-in vibrating screen, the online particle size analyzer, and the mineral composition detection probe provides real-time data support for the preliminary screening of fine sand. This combination enables the analysis of the particle size and composition of the material before it enters the vibrating screen, thus achieving more efficient classification and processing. In traditional technologies, such pre-analysis means are often lacking, resulting in less than ideal subsequent processing effects.

[0016] In the multi-layer screening unit, the design of the circular vibrating screen enables the fine sand to undergo multiple screenings. Stainless steel screen mesh pieces with different pore sizes are installed on each screen surface. Such a design can effectively separate fine sand of different particle sizes, thereby improving the purity of the final recovery. At the same time, the setting of the online particle size analyzer and the mineral composition detection probe at the feeding point enables real-time monitoring and adjustment of the entire screening process, ensuring the stability and accuracy of the screening effect. Compared with existing technologies, traditional systems usually cannot achieve real-time adjustment, resulting in low efficiency in fine sand processing.

[0017] In the cleaning and dewatering unit, the introduction of the vibrating sand washer, combined with adjustable multi-group vibrators, improves the cleaning efficiency of fine sand. Traditional cleaning methods often rely on gravity or simple water flow flushing, with limited effects. The vibrating sand washer of this system can achieve more thorough cleaning by adjusting the position and frequency of the vibrators, removing impurities and dirt in the fine sand, and improving the purity of the product. Such a design is relatively rare in existing technologies. Usually, the cleaning unit lacks the ability of dynamic adjustment, resulting in poor cleaning effects.

[0018] The design of the fine sand flotation machine used in the flotation and de-sludging unit is also an innovation. Traditional flotation machines usually rely on fixed parameters for the dosage of chemicals and the flotation time, lacking the dynamic adaptability to the mineral composition and content of fine sand. However, through the feedback of the online particle size analyzer and the mineral composition analysis probe, this system can dynamically adjust the flotation time, flushing intensity, and flotation concentration, achieving more precise flotation treatment. This dynamic adjustment ability not only improves the flotation efficiency but also effectively enhances the recovery rate of fine sand, reducing resource waste. Especially when dealing with complex minerals, it can show better effects.

[0019] This recovery and treatment system overcomes many deficiencies in traditional fine sand recovery and treatment through multi-level screening, dynamic cleaning, and intelligent flotation designs, demonstrating higher processing efficiency and accuracy, and providing a more efficient and reliable solution for the secondary application of fine sand.

[0020] As a preferred embodiment, it further includes a pneumatic separation unit. The pneumatic separation unit is started after the flotation and de-sludging unit. The pneumatic separation unit includes a spiral chute and / or a pneumatic separator. Two or more groups of spiral chutes are connected in series or in parallel. The fine sand forms an inclined forward and reverse curve movement through the grading roller and the eccentric movement of the eccentric device.

[0021] As a preferred embodiment, the particle size - composition two - dimensional classification algorithm divides fine sand into several particle size intervals, forms a real - time particle size distribution curve based on the real - time scanning of the sieve surface, takes the interval where the maximum particle size on the curve is located as the target object, takes the overlapping part with the previous particle size interval as the effective reference object, compares it with the characteristic value of the current reference object, if it is less than the set allowable error value, it is classified into the next interval, otherwise it enters the next cycle as a non - target object, and continuously iterates to eliminate non - target objects.

[0022] As a preferred embodiment, the real - time particle size distribution curve is obtained by measurement with an on - line particle size analyzer, and the characteristic values include particle size and composition.

[0023] As a preferred embodiment, after obtaining the characteristic values in the real - time particle size distribution curve, through analyzing the particle size and composition, optimizing the process of the analysis results, evaluating the separation effect by comparing the peak ratio of the particle size distribution in adjacent intervals and the percentage of the proportion of this particle size segment in the whole particle size distribution, and performing feedback adjustment on the process parameters.

[0024] After adopting the above technical solutions, the beneficial effects of the present invention are as follows: Through the optimized screening and cleaning processes, the system can effectively improve the recovery rate of fine sand. The combination of the single - layer screening unit and the multi - layer screening unit enables more accurate classification of fine sand during the screening process, reduces the phenomenon of component mixing, and thus improves the purity of the final recovered product. This improvement can not only meet the higher - standard market demands but also bring greater economic benefits to users.

[0025] The design of the vibrating sand washer in the cleaning and dewatering unit significantly enhances the cleaning effect. Through adjustable multi - group vibrators, the system can remove impurities and soil in the fine sand during the cleaning process, ensuring the quality of the recovered fine sand. This efficient cleaning ability reduces resource waste caused by incomplete cleaning and helps improve the overall production efficiency.

[0026] The dynamic adjustment ability of the flotation and de - sludging unit enables the system to adapt to changes in different mineral compositions and optimize the flotation treatment process. By real - time monitoring the mineral composition of the fine sand, the system can automatically adjust the dosage of chemicals and the flotation time, thereby improving the efficiency and accuracy of flotation. This intelligent processing method enables users to still obtain stable recovery effects when facing complex minerals, reducing production costs.

[0027] The fully automated design of this system reduces the dependence on manual operations and improves the overall work efficiency. Through real-time data monitoring and dynamic adjustment, operators can more effectively grasp the production situation, timely adjust strategies, and reduce errors and fluctuations caused by human factors. This feature enables the system to maintain a good working state in various production environments, enhancing the reliability and stability of production.

[0028] The efficient operation of the system also brings considerable economic benefits to the enterprise. By improving the fine sand recovery rate, increasing product quality, and reducing production costs, the enterprise can maintain competitiveness in the market and enhance its market share. Especially in the context of increasingly scarce resources, optimizing the recovery and utilization of resources has important economic and social value.

[0029] This recovery and treatment system provides strong technical support for the secondary application of fine sand by improving the recovery efficiency, cleaning quality, and flotation ability of fine sand, promoting the sustainable development of related industries, and having significant economic and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 It is a system flow chart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0033] Embodiment:

[0034] As Figure 1As shown in the figure, this recycling and processing system is designed and implemented for the scenario of recycling and utilization of construction waste fine sand. The system consists of a single-layer screening unit, a multi-layer screening unit, a cleaning and dewatering unit, and a flotation and de-sludging unit to form a full-automatic processing line. The raw material fine sand enters the single-layer screening unit through a belt conveyor at a feeding rate of 3t / h. The vibrating screen is equipped with two groups of adjustable electromagnetic vibrators (adjustable from 0 to 50Hz), and the screen surface uses a stainless steel screen with a pore size of 5mm. The on-line particle size analyzer (laser diffraction type) at the feeding port and the XRF mineral composition detection probe scan the material in real time. When the detected SiO 2 content is less than 75%, the control chip automatically increases the vibration frequency to 45Hz and adjusts the amplitude to 5mm, driving the screen surface to form a reverse movement, and discharging the coarse particles with a high impurity content (>5mm) into the waste bin; after the undersize enters the multi-layer screening unit, the three-stage circular vibrating screen group (screen mesh pore sizes of 2mm / 1mm / 0.6mm) dynamically adjusts the screen surface inclination angle (10°-25°) through a servo motor. When the clay mineral content detected on the second-layer screen surface exceeds 15%, the high-frequency micro-vibration mode (60Hz / 2mm) is activated to effectively separate the muddy fine sand; the 0.6-1mm finished sand after three-stage screening enters the cleaning and dewatering unit.

[0035] The double-shaft eccentric block vibrator of the vibrating sand washer automatically switches the working mode according to the previous mineral data: when organic matter residues are detected, the strong flushing mode (water pressure 0.3MPa) is started, and when carbonate components are present, weak acid washing (pH = 5.5) is enabled; the final material enters the flotation and de-sludging unit. The fine sand flotation machine automatically adjusts the dosage of sodium dodecyl sulfonate reagent (0.8kg / t) according to the D50 value (85μm) fed back by the on-line particle size analyzer. The ultrasonic generator (28kHz) in the flotation cell dynamically adjusts the action intensity according to the clay mineral content, achieving a fine sand recovery rate of over 98%. The system realizes full-process linkage through a PLC controller. Each unit vibrator is equipped with a vibration sensor to monitor the operating status in real time. The data is uploaded to the cloud analysis platform through the industrial Internet of Things gateway. When the detected screen clogging index > 0.8, the compressed air back-blowing system is automatically triggered. The processed fine sand meets the building sand standard and can be directly used for the preparation of C30 concrete. The water resource recycling rate of the whole system reaches 95%, and it saves 30% energy compared with the traditional process.

[0036] It also includes an air separation unit, which is started after the flotation de-sludging unit. The air separation unit includes a spiral chute and / or an air separator. Two or more groups of spiral chutes are connected in series or in parallel. Fine sand forms an inclined forward and reverse curve motion through the grading roller and the eccentric motion of the eccentric device. In this technical solution, the air separation unit is started after the flotation de-sludging unit and includes a spiral chute and / or an air separator. The application of this design in a specific working scenario can effectively achieve the separation and treatment of fine sand. By adopting a series or parallel configuration of two or more groups of spiral chutes, after passing through the grading roller and the eccentric device, the fine sand forms an inclined forward and reverse curve motion, which can effectively improve the sorting efficiency of the fine sand. In actual operation, the physical characteristics and particle size differences of the fine sand are fully utilized to effectively separate fine sand of different particle sizes and maximize the recycling of resources. This air separation technology is particularly suitable for the mining, construction sand and gravel, and environmental protection industries, which can improve the quality of fine sand, reduce the generation of waste, and promote sustainable development.

[0037] The particle size-composition two-dimensional classification algorithm divides fine sand into several particle size intervals, forms a real-time particle size distribution curve based on the real-time scanning of the sieve surface, takes the interval where the maximum particle size on the curve is located as the target object, takes the overlapping part with the previous particle size interval as the effective reference object, compares it with the characteristic value of the current reference object, if it is less than the set allowable error value, it is classified into the next interval, otherwise it enters the next cycle as a non-target object, and continuously iterates to eliminate non-target objects.

[0038] In the implementation of the particle size-composition two-dimensional classification algorithm, fine sand is divided into several particle size intervals, a particle size distribution curve is formed by real-time scanning, and the interval where the maximum particle size on the curve is located is taken as the target object. The application of this technical solution in a specific working scenario can achieve precise classification of fine sand particles. Through continuous iterative judgment, the algorithm can effectively eliminate non-target objects that do not meet the requirements, ensuring that the finally selected fine sand meets the set standards in terms of particle size and composition. This precise classification method can significantly improve the quality and added value of products and optimize the resource utilization efficiency in the fields of mineral resource sorting, soil remediation, and building materials.

[0039] The real-time particle size distribution curve is obtained by measurement with an on-line particle size analyzer, and the characteristic values include particle size and composition. The real-time particle size distribution curve is obtained by measurement with an on-line particle size analyzer, and its characteristic values include particle size and composition. The application of this design in specific working scenarios ensures the real-time monitoring of the characteristics of fine sand, enabling operation decisions in the production process to be based on scientific data support. In the mining and materials processing industries, the real-time obtained particle size and composition data can enable operators to adjust the processing technology in a timely manner to ensure production efficiency and product quality. This real-time monitoring method can effectively reduce the errors of manual detection, improve the automation level of the production process, and provide strong support for modern production.

[0040] After obtaining the characteristic values in the real-time particle size distribution curve, by analyzing the particle size and composition, optimizing the process according to the analysis results, evaluating the separation effect by comparing the peak ratio of the particle size distribution in adjacent intervals and the percentage of the particle size range in the whole particle size distribution, and providing feedback adjustment for the process parameters.

[0041] After obtaining the characteristic values in the real-time particle size distribution curve, by analyzing the particle size and composition, the implementation plan of the optimized process is determined. In specific working scenarios, this design can evaluate the separation effect by comparing the peak ratio of the particle size distribution in adjacent intervals and its proportion, so as to realize the effective feedback adjustment of the process parameters. This optimization method based on data analysis can quickly respond to changes in the production process, improve the flexibility and adaptability of the production process. Especially when facing raw material changes or market demand fluctuations, it can adjust the production strategy in a timely manner to maintain the consistency and excellence of the product. In industries such as mining, building materials, and environmental protection, this can significantly improve production efficiency and resource utilization rate, and promote the efficient operation of the entire industrial chain.

[0042] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A recycling system for secondary use of fine sand, characterized in that: It includes a single-layer screening unit, a multi-layer screening unit, a cleaning and dehydration unit and a flotation and desludging unit arranged in sequence according to the recovery path; The single-layer screening unit is equipped with a vibrating screen, and the vibrating screen is provided with multiple adjustable vibrators. The installation position of the vibrators is controlled and adjusted by the control chip. The fine sand components are classified according to the particle size-component dual-dimensional classification algorithm, and the frequency and amplitude are adjusted according to the classification results. An online particle size analyzer and a mineral component detection probe are provided at the feed of the vibrating screen. The material performs forward or reverse screening motion on the screen surface; and the classification data is imported into the cleaning and dehydration unit. The multi-layer screening unit has a built-in circular vibrating screen, and a plurality of circular vibrating screen frame screen surfaces are arranged on the circular vibrating screen frame screen surfaces, wherein stainless steel screen meshes with different apertures are installed on the circular vibrating screen frame screen surfaces, and multiple groups of adjustable vibrators are arranged on the screen surfaces, and an online particle size analyzer and a mineral composition detection probe are arranged at the feeding place of the circular vibrating screen, and a plurality of screen holes and screen meshes are arranged on the screen surface, and a forward or reverse screening motion is performed on the screen surface; The cleaning and dehydration unit is a vibrating sand washing machine, which is provided with multiple groups of adjustable vibrators, and the installation position of the vibrators is adjusted in real time according to the classification data; The flotation desludging unit is a fine sand flotation machine, which is provided with fine sand and water, and is filled with flotation agent. The flotation machine is provided with a dosing device, which automatically controls the dosing module according to the particle size analysis result of the online particle size analyzer, and controls the flotation desludging path according to the result of the online mineral composition analysis probe; the flotation time, flushing intensity and flotation concentration are dynamically adjusted according to the mineral composition and content of the fine sand.

2. A recycling system for secondary use of fine sand as claimed in claim 1, characterized in that: It also includes an air separation unit, which is started after the flotation desliming unit. The air separation unit includes a spiral chute and / or an air separator. Two or more spiral chutes are connected in series or in parallel. Fine sand moves eccentrically through grading rollers and eccentric devices to form an inclined forward and reverse curvilinear motion.

3. A recycling system for secondary use of fine sand as claimed in claim 1, characterized in that: The particle size-composition dual-dimensional classification algorithm divides fine sand into several particle size intervals, forms a real-time particle size distribution curve based on real-time scanning of the screen surface, takes the interval where the maximum particle size on the curve is located as the target object, takes the part overlapping with the previous particle size interval as the effective reference object, and compares it with the current reference object feature value. If it is less than the set allowable error value, it is classified into the next interval, otherwise it enters the next cycle as a non-target object, and eliminates non-target objects through continuous iteration.

4. A recycling system for secondary use of fine sand as claimed in claim 3, characterized in that: The real-time particle size distribution curve is obtained by measuring with an online particle size analyzer, and the characteristic values ​​include particle size and composition.

5. A recycling system for secondary use of fine sand as claimed in claim 4, characterized in that: After obtaining the characteristic values ​​in the real-time particle size distribution curve, the particle size and composition are analyzed, and the process is optimized based on the analysis results. By comparing the peak ratios of the particle size distribution in adjacent intervals and the percentage of the particle size segment in the entire particle size distribution, the sorting effect is evaluated and the process parameters are feedback-adjusted.

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