A method for treating light fraction of stale garbage in stages

Abstract

The present application relates to solid waste resource utilization and intelligent sorting technical field, especially disclose a kind of stale garbage light material step-by-step processing method, comprising the following steps: S1, coarse light material is removed iron impurity by chain plate conveying and magnetic separation, then broken loose and is disintegrated, and surface silt is stripped by flexible kneading, and loose material is obtained;S2, multi-stage vibration screen is classified into fine material, intermediate particle size component, large particle size component, and fine material is directly backfilled;S3, the remaining material is air separated to remove heavy impurities, and cleanable sorting material is obtained;S4, the moisture content of material is regulated and surface is cleaned, and mud film, water film are broken to meet the photoelectric identification condition;S5, material is divided into high-value plastic, low-value combustible, chlorine-containing risk component and residual impurities by photoelectric sorting;S6, high-value plastic enters materialization or chemical recycling path, low-value combustible component prepares RDF, and chlorine-containing component is disposed separately without harm.The present application can significantly improve the sorting accuracy, realize light material quality step-by-step high-value resource utilization.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and intelligent sorting technology, and in particular discloses a method for the tiered treatment of lightweight materials from aged waste. Background Technology

[0002] Stale waste refers to solid waste that has been excavated and screened after long-term landfilling or stockpiling. After screening, it usually forms components such as humus, aggregate and lightweight materials. The lightweight materials mainly include combustible or recyclable materials such as plastics, films, wood fragments, textiles and a small amount of composite materials.

[0003] However, existing resource recovery processes for lightweight materials from aged waste are relatively rudimentary. They lack systematic pretreatment processes designed to address the inherent characteristics of aged waste, such as clumping, surface mud and sand compaction, high moisture content, and mixed components formed during long-term landfilling. These processes generally suffer from insufficient material disintegration, ineffective removal of surface mud film, and severe impurity contamination. Consequently, subsequent photoelectric sorting and identification suffer from significant interference, poor sorting accuracy, and low high-value plastic recovery rates. Furthermore, the resource recovery pathway for lightweight materials is singular, failing to match materialization and energy recovery methods according to material quality differences. Ultimately, this results in a large waste of recyclable resources, hindering the high-value and stable resource utilization of lightweight materials from aged waste.

[0004] Therefore, there is an urgent need for a method that can systematically pre-treat lightweight materials from aged waste and achieve multi-level sorting and tiered resource utilization. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a method for systematically pre-treating lightweight materials of aged waste and realizing multi-level sorting and tiered resource utilization; it is mainly applied to the treatment of aged waste in existing landfills, the construction of waste-free cities, the high-value recycling of renewable resources, and the reduction, harmlessness and resource utilization of solid waste, and is suitable for special treatment conditions of lightweight materials of aged waste with high mud content, high water content, high impurities and complex composition.

[0006] To achieve the above objectives, the present invention provides a method for the tiered treatment of lightweight materials from aged waste, comprising the following steps: S1. The coarse lightweight material obtained from the screening of aged garbage is sent to the magnetic separation process via a chain conveyor to remove ferromagnetic metal impurities from the material. Then it is sent to the crushing and loosening process to separate the entangled, agglomerated and mud-attached lightweight material. After that, it is sent to the kneading process for flexible grinding to peel off the mud and sand adhering to the surface, so that the lightweight material is formed into a loose material. S2. The loose material is fed into a multi-stage screening device. The vibrating screen of the multi-stage screening device is used to separate the material into fine material components, intermediate particle size components and large particle size lightweight components according to the particle size. The fine material components are separated as mud and sand enrichment or backfilled for reuse, while the intermediate particle size components and / or large particle size lightweight components are sent to subsequent processing. S3. The light components entering the subsequent processing are air-classified to remove impurities such as mud, sand, stones, glass, metal and high-density impurities, so as to obtain sortable light materials. S4. Adjust the moisture content and clean the surface of the sortable lightweight material obtained in step S3 to reduce the mud film and water film on the surface of the lightweight material and achieve photoelectric recognition conditions. S5. The lightweight material obtained in step S4 is sent to the photoelectric sorting equipment. Based on one or more of the identification results of material, color, shape, chlorine risk, and calorific value, the lightweight material is divided into high-value plastic components, low-value combustible components, chlorine-containing risk components and residual impurity components. S6. Send the high-value plastic components into the material utilization or chemical recycling path, send the low-value combustible components into the RDF preparation or incineration power generation process, and separately remove or carry out special harmless treatment of chlorine-containing risk components.

[0007] Furthermore, in step S1, the crushing and loosening process employs one or more combinations of low-speed shearing, tearing, spreading, reverse spreading, or airflow loosening to disintegrate the film, cloth strips, woven bags, and lightweight wooden materials without excessive crushing; in step S1, the crushing and loosening process simultaneously removes mud and sand, using the friction and collision between the crushing parts and the screen surface, spreading parts, or cylinder wall to remove the mud and sand adhering to the surface of the lightweight materials.

[0008] Furthermore, in step S1, the magnetic separation process uses a suspended permanent magnet separator, which is mounted above the discharge end of the chain conveyor to adsorb and remove ferromagnetic impurities from the coarse and light materials. After being processed by the magnetic separation process, the coarse and light materials are first crushed by biaxial shearing to a particle size ≤100mm before being fed into the kneading equipment. The kneading equipment uses two sets of flexible kneading rollers that rotate in opposite directions at different speeds. The rollers are covered with a wear-resistant rubber lining so that the main body of the material remains intact during the kneading process, and only the surface-adhered impurities are peeled off. The material processed by the kneading equipment is then screened by a multi-stage screening equipment. The fine material obtained by screening consists of a particle size of less than 10 mm, an intermediate particle size consists of a particle size of 10 mm to 30 mm, and a large particle size lightweight component consists of a particle size of more than 30 mm. The multi-stage screening equipment is a double-layer variable tilt angle vibrating screen.

[0009] Furthermore, in step S2, the intermediate particle size components are selected to enter the secondary air classification, return to the crushing and loosening process, or enter the RDF preparation process according to their mud content, plastic content, or moisture content.

[0010] Furthermore, the air classification and impurity removal in step S3 includes primary air classification and secondary air classification. Large-diameter lightweight materials are sent to the primary air classification to separate heavy aggregates; medium-diameter lightweight materials are sent to the secondary air classification to deeply remove fine sand and small-particle heavy impurities; wherein, the secondary air classification is used to separate lightweight plastics, films, cloth strips, paper, wood and foam into layers.

[0011] Furthermore, in step S3, a circulating hot air system is also provided. The primary and secondary air separation systems share the circulating hot air system. The air separation airflow generated by the two-stage air separation equipment is recycled after dust removal and heating, so that the moisture content of large-diameter lightweight materials and medium-diameter lightweight materials is reduced to below 20%.

[0012] Furthermore, in step S4, the moisture content control adopts one or more combinations of mechanical extrusion dehydration, centrifugal dehydration, hot air drying, waste heat drying, negative pressure dehumidification, air knife blowing, or friction cleaning.

[0013] Furthermore, before step S5, there is also a material distribution step, which uses a buffer hopper, star feeder, vibrating material distributor, pressure hood, flow stabilizing guide hood or high-speed conveyor belt to make the lightweight material enter the photoelectric recognition area in a single layer or low stacking state.

[0014] Furthermore, the multimodal photoelectric sorting process in step S5 employs at least two of the following for fusion recognition: line scanning AI visual recognition, near-infrared recognition, hyperspectral recognition, fluorescence recognition, and metal recognition. The recognition algorithm is trained based on a dedicated spectral database of lightweight waste materials. Hyperspectral recognition is used to distinguish between PET, PE, PP, PVC, HDPE, LDPE, or other plastic materials. AI visual recognition is used to determine the material's shape, color, degree of contamination, or stacking status. Fluorescence recognition is used to identify aged plastics or fluorescent components. Metal recognition is used to remove metal impurities.

[0015] Further, in step S5, PVC, CPVC, or other chlorine-containing components are identified and removed first, and the remaining materials are then sorted into high-value plastic components and low-value combustible components. The high-value plastic components include one or more of PP, PE, PET, HDPE, or LDPE, and are respectively sent to recycling granulation, pyrolysis refining, gasification hydrogen extraction, or other chemical recycling paths according to cleanliness, material purity, or degree of pollution. The low-value combustible components include one or more of wood, cloth strips, paper, low-value plastics, or foam, and are prepared into RDF after crushing, drying, blending, and compression molding.

[0016] Furthermore, when the proportion of high-value plastic components identified by the multimodal photoelectric sorting process is lower than the preset value, the batch of materials is preferentially diverted to the RDF preparation path; when the proportion of chlorine-containing risk components is higher than the preset value, the priority of chlorine-containing components is increased and the proportion of them entering the RDF path is reduced; fine material components are used for in-situ backfilling after sludge and sand stabilization treatment, intermediate particle size components are diverted to the RDF preparation path after secondary air classification or secondary screening and testing to ensure that the sand content and plasticity meet the standards, and materials with excessive impurities are returned to the front-end crushing and loosening process for reprocessing, and large particle size lightweight components are diverted to the materialization or energy utilization path after photoelectric sorting.

[0017] Furthermore, the material utilization path involves purifying, removing impurities from, and crushing high-value plastic components to prepare recycled plastic granules; the energy utilization path includes two methods: one is to crush and dry low-value combustible components and then press them into RDF fuel for incineration power generation; the other is to send high-value plastics into a pyrolysis device to prepare fuel oil and gas and extract hydrogen.

[0018] This invention constructs a complete closed-loop process system encompassing magnetic separation for impurity removal, crushing and loosening, flexible kneading and dissociation, particle size grading screening, differential air classification, material drying and cleaning, multimodal intelligent sorting, and differentiated tiered resource utilization. First, a chain conveyor combined with pre-conduction magnetic separation thoroughly removes ferromagnetic impurities, protecting downstream equipment and avoiding metal interference. Next, low-loss crushing and loosening combined with flexible kneading achieves agglomeration and efficient removal of surface mud and sand without damaging the material's structure. Multi-stage particle size screening and tiered air classification achieve gradient impurity removal and dehumidification, precisely eliminating surface mud and water films to meet the high-precision requirements of photoelectric recognition. Finally, multimodal fusion recognition technology enables refined component classification of lightweight materials. Based on the quality, material composition, and pollution risk of different material components, differentiated tiered utilization paths are matched for plastic material recycling, chemical recovery, RDF preparation, and harmless disposal, achieving a systematic, refined, and intelligent process throughout the entire process.

[0019] The beneficial effects of this invention are as follows: By coupling multi-stage pretreatment with tiered sorting and differentiated resource utilization processes, this invention fundamentally solves the core pain points of traditional processes, such as poor disaggregation of aged light materials, incomplete impurity removal, low photoelectric recognition accuracy, and limited resource utilization. It effectively improves the cleanliness and sorting accuracy of aged waste light materials, and significantly increases the recycling purity and recovery rate of high-value plastics. At the same time, by matching material classification with corresponding resource utilization paths, it maximizes the tiered value utilization of inferior materials (harmlessness), mid-range materials (energy utilization), and high-quality materials (material utilization). This significantly improves the resource utilization rate and product added value of aged waste light materials, reduces the pressure of solid waste landfill and incineration, and meets the needs of green circular development of solid waste under the zero-waste city and dual-carbon policies. The process has strong stability, wide adaptability, and outstanding industrialization value. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the steps of the tiered treatment method for lightweight waste of the present invention. Figure 2 This is a flowchart illustrating the overall process flow of the tiered treatment method for lightweight waste materials of the present invention. Figure 3 This is a flowchart of the pretreatment and gradient sieving section of the present invention; Figure 4 This is a flow chart of the graded air classification and surface cleaning and drying section of the present invention; Figure 5 This is a flowchart of the multimodal photoelectric sorting and cascade resource recovery process of the present invention. Detailed Implementation

[0021] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0022] Please see Figures 1 to 5 As shown, the present invention provides a tiered treatment method for lightweight materials from aged waste, which is mainly applied to the coarse lightweight material treatment line after screening aged waste in existing landfills. The coarse lightweight material is the lightweight component obtained after aged waste is screened by a drum screen, mainly including plastic film, woven bags, waste textiles, wood chips, waste paper, and impurities such as mud, sand, iron blocks, and stones. The entire treatment line is arranged along the material flow direction in sequence as follows: chain conveyor, magnetic separation process, crushing and loosening process, kneading and dissociation process, multi-stage screening process, grading and air separation process, surface cleaning and drying process, material distribution process, multi-modal photoelectric separation process, and quality resource recovery process. Each process is connected by a sealed chute or belt conveyor, and the entire process is operated under closed negative pressure.

[0023] Specifically, in this embodiment, the crushing and loosening process adopts a low-speed twin-shaft shear crusher. The cutter shaft is controlled to operate in a low-speed range, and the cutter body adopts a wide-tooth rhomboid structure with a large distance between adjacent cutter bodies. The material is sheared, torn, and dispersed by the counter-rotating cutter shaft. In conjunction with the material-dispersing ribs on the inner wall of the chamber, the material is dispersed in the opposite direction, so that the tangled films, strips of cloth, and woven bags are fully untangled. At the same time, the material is prevented from being crushed due to excessive cutting by the blades. During the rolling process in the crushing chamber, the material continuously rubs and collides with the cutter body, the chamber wall, and the bottom screen, so that the hardened mud and sand layer attached to the surface of the lightweight material is loosened and falls off, and is initially discharged through the gaps in the screen.

[0024] Compared to existing high-speed fine crushers, this solution not only de-agglomerates agglomerated materials but also avoids over-crushing, reducing the probability of mud and sand embedding into material fibers and gaps. Simultaneously, it completes preliminary mud and sand stripping, reducing the load on subsequent desliming processes.

[0025] Specifically, in this embodiment, the magnetic separation process uses a suspended permanent magnet separator, which is horizontally mounted directly above the discharge end of the chain conveyor and maintains a set distance from the surface of the chain belt. When the material passes under the separator with the belt, ferromagnetic impurities such as iron blocks, iron wires, and iron sheets in the material are magnetically attracted and removed from the material flow, and are periodically discharged through the iron unloading mechanism.

[0026] After magnetic separation, the material falls into the lower twin-shaft shear crusher. The particle size of the crushed material is controlled within 100mm, and then it is sent to the kneading equipment through a sealed chute.

[0027] The kneading equipment uses two sets of parallel differential kneading rollers. The two rollers rotate in opposite directions with a speed difference. The outer wall of the rollers is fully covered with a wear-resistant rubber lining. The distance between the two rollers can be adjusted by adjusting the screw on the side. The material falls from above the two rollers and enters the gap between the rollers as the rollers rotate. It is subjected to continuous flexible kneading action, and the mud and sand adhering to the surface are completely kneaded off, while the main body of lightweight materials such as plastics, fabrics, and wood remains intact.

[0028] The kneaded material falls directly into the double-layer variable-angle vibrating screen below. The screen surface of the vibrating screen gradually increases in inclination along the direction of material movement. The upper screen mesh has a diameter of 30mm, and the lower screen mesh has a diameter of 10mm. After the material is vibrated and screened, it forms three-stage products: large-diameter lightweight material with a particle size greater than 30mm is discharged from the end of the upper screen; the intermediate particle size component with a particle size of 10mm to 30mm is discharged from the side opening between the two screens; and the fine material component with a particle size less than 10mm passes through the lower screen and is discharged from the bottom. The fine material is mainly composed of mud, sand and humus. After collection and stabilization testing, it can be directly used for site backfilling if it meets the standards.

[0029] Compared to the existing technology of directly screening after crushing, this solution removes hard metal impurities in advance through pre-magnetic separation, avoiding damage to subsequent blades and equipment. Combined with flexible kneading, it achieves deep desliming of the material surface, and then achieves precise particle size classification through variable tilt gradient screening, thereby improving the cleanliness and compatibility of the feed to subsequent sorting processes from the source.

[0030] Preferably, the discharge chute for the intermediate particle size fraction is equipped with an online detection probe and a three-way diversion baffle, which can detect the mud content, plastic content, and moisture content of the material in real time. When the indicators meet the requirements for air separation feeding, the three-way baffle is connected to the secondary air separation feed port; When the material has a high agglomeration rate and excessive mud content, the baffle is connected to the return conveyor belt to send the material back to the crushing and loosening process for reprocessing. When the material has a very low plasticity and is mainly composed of wood chips and shredded fabric, it can be directly fed into the RDF preparation process.

[0031] Compared to the fixed material flow direction process layout in existing technologies, this solution can flexibly switch the treatment path according to the actual quality of intermediate particle size materials, avoiding the entry of high mud content materials into subsequent sorting equipment and affecting accuracy, and also reducing the energy waste of ineffective sorting of low value materials.

[0032] Specifically, in this embodiment, the air separation and impurity removal process is divided into two independent units: primary coarse air separation and secondary fine air separation. Large-diameter lightweight materials are fed into a cross-flow primary air separator, which is configured with a large air volume and low wind speed. During the process of the material falling freely from the feed inlet, the lightweight components are blown to the lightweight silo by the horizontal airflow, while heavy aggregates such as stones, glass, and large metal particles fall to the heavy aggregate silo by their own weight, thus completing the coarse separation. The intermediate particle size components are fed into a vertical two-stage air separator, which uses a small air volume and high air velocity configuration. The material is layered step by step in the rising airflow. Heavy particles such as fine sand and small stones are discharged from the bottom, while light plastics, films, cloth strips, paper, wood, foam and other materials are layered and diverted according to their density differences and discharged from the discharge ports at different heights, thus completing the fine impurity removal.

[0033] Compared to the existing single-stage uniform wind separation process, this solution matches different wind velocities and flow field structures for materials of different particle sizes. This avoids the inability to separate large-particle-size materials due to insufficient wind speed, and also avoids the entrainment of fine sand by excessive wind speed for small-particle-size materials. The removal of heavy impurities is more thorough, and the final sortable light materials have a lower sand content.

[0034] Preferably, the primary and secondary air separation systems share a circulating hot air system. The air outlet of the air separation equipment is connected to the dust removal device through a pipe. After removing the dust carried in the airflow, the airflow is sent into the heating unit to be heated, and then flows back to the air inlet of the two-stage air separation system through the air supply pipe to form a closed hot air circulation.

[0035] While separating light and heavy materials, the circulating hot air comes into full contact with the materials to remove surface moisture, reducing the moisture content of the materials from the two-stage air separation to below 20%.

[0036] In the existing technology, the direct-discharge ambient temperature air separation process is used. This solution adopts a closed-loop hot air circulation, which reduces the fugitive emission of waste gas on the one hand, and simultaneously realizes the pre-drying of materials, improving the clarity of subsequent photoelectric recognition, and the energy consumption is lower due to heat recycling.

[0037] Specifically, in this embodiment, the moisture content control and surface cleaning in step S4 adopts a combination of hot air drying and air knife blowing. The material after air separation is spread flat on the conveyor belt, first passing through the low temperature hot air drying section to further reduce the moisture content, and then passing through the high pressure air knife section. Multiple sets of air knives are arranged along the width of the conveyor belt, and the high-speed airflow obliquely blows the surface of the material to remove residual dust and mud film, while breaking the water film on the surface of the material, so that the cleanliness and dryness of the material surface meet the requirements of photoelectric recognition.

[0038] Compared to a single hot air drying process, this solution combines air knife physical purging, which can more efficiently break down mud and water films adhering to the surface of materials, prevent mud films from obscuring the material's own characteristics, and ensure the accuracy of subsequent photoelectric recognition.

[0039] Preferably, a material distribution process is set before the photoelectric sorting process, which includes a buffer hopper, a star feeder, a vibrating material distributor and a high-speed sorting conveyor belt in sequence. The buffer hopper temporarily stores the cleaned material, and the material is quantitatively discharged through the bottom star feeder. After the material falls into the vibrating material distributor, it is evenly spread out under the action of high frequency vibration and spread flat on the high-speed sorting conveyor belt below, so that the material enters the photoelectric recognition area in a single layer and low stacking state.

[0040] Compared to the direct feeding method in existing technologies, this solution achieves single-layer flat laying of materials through multi-level uniform material distribution, which greatly reduces the identification error and missed selection caused by material stacking and obstruction, and effectively improves the accuracy and purity of photoelectric sorting.

[0041] Specifically, in this embodiment, the multimodal photoelectric sorting process adopts a decision-level fusion scheme of multiple sensors, including line scanning AI vision, near-infrared hyperspectral, fluorescence recognition and metal recognition. Multiple sensors are sequentially mounted above the belt along the conveying direction of the sorting conveyor belt.

[0042] The hyperspectral sensor uses multi-band near-infrared spectral imaging, which can accurately distinguish different plastic materials such as PET, PE, PP, PVC, HDPE, and LDPE. Line scan AI vision cameras collect visible light images of materials to determine their shape, color, contamination level, and stacking status. Fluorescent sensors can excite and identify aged plastics and impurities containing fluorescent agents; metal sensors can detect and locate tiny metal impurities.

[0043] Data from all sensors is sent to the device's internal computing platform. Based on a recognition algorithm trained on a dedicated spectral database of lightweight waste, the algorithm performs decision-level fusion judgment and outputs information on the material's category, location, and size.

[0044] Compared to existing single-vision or single-spectrum recognition solutions, this solution's multimodal fusion recognition can effectively overcome the difficulties in recognizing aged plastics, surface contamination, and dull colors in aged waste. It offers higher material recognition accuracy, can distinguish a wider variety of materials, and is suitable for the complex material handling conditions of aged waste.

[0045] Specifically, in this embodiment, the photoelectric sorting adopts a two-stage rejection operation logic, with a first-stage spray valve group and a second-stage spray valve group set sequentially along the conveyor belt direction; The identification system prioritizes locating chlorine-containing components such as PVC and CPVC, as well as residual metal impurities. These are then blown into the chlorine-containing risk component silo via the first-stage spray valve assembly, where they are collected separately and subjected to specialized harmless disposal. The remaining material continues to be conveyed forward, and the identification system locates high-value plastic components such as PP, PE, and PET. These are then blown into the high-value plastic component silo via the second-stage spray valve assembly. The remaining material that is not blown out is the low-value flammable component, which falls naturally into the low-value silo from the end of the conveyor belt.

[0046] High-value plastic components are diverted based on the cleanliness, material purity, and degree of contamination detected by subsequent online testing: materials with high cleanliness and purity are sent to the recycling granulation production line to prepare recycled plastic granules, thereby realizing the utilization of materials; Materials with higher pollution levels and lower purity are sent to pyrolysis refining or gasification hydrogen extraction units for chemical recovery. Low-value combustible components include wood, cloth strips, paper, low-value plastics, foam, etc., which are fed into the RDF preparation line and processed through crushing, drying, blending and compression molding to produce RDF-derived fuel for incineration power generation.

[0047] Compared to existing single-stage, one-time sorting solutions, this solution prioritizes the removal of chlorine-containing harmful components, preventing chlorine-containing materials from entering subsequent resource recovery stages at the source, reducing the risk of dioxin emissions. At the same time, it matches differentiated recycling paths according to the quality of high-value plastics, maximizing the utilization of resource value.

[0048] Preferably, the sorting system has a built-in component ratio dynamic control module, which can count the proportion of each component identified by multimodal photoelectric sorting in real time. When the proportion of high-value plastic components is detected to be lower than the preset threshold, the system automatically adjusts the diversion baffle to prioritize the diversion of the entire batch of material to the RDF preparation path, thus avoiding energy waste caused by low-yield sorting. When the proportion of chlorine-containing risk components detected is higher than the preset threshold, the system automatically increases the rejection priority and jet intensity of the first-stage spray valve group to ensure that chlorine-containing components are fully removed and reduce the proportion of them mixed into RDF or high-value plastics.

[0049] Fine particles, after being stabilized by mud and sand, are used for in-situ backfilling. Medium-sized particles, after secondary air classification or secondary screening, are diverted to the RDF (Regenerative Thermal Dioxide) preparation path if their sand and plasticity content meets standards, and returned to the front-end crushing and loosening process for reprocessing if their impurity content exceeds standards. Large-sized lightweight particles are separated by photoelectric sorting and then enter either the material utilization or energy utilization path. This solution can dynamically adjust the disposal strategy according to fluctuations in the incoming material composition, adapting to the characteristics of large fluctuations in the composition of aged waste, offering superior operational flexibility and economy.

[0050] Specifically, in this embodiment, the material utilization path involves processing high-value plastic components through crushing, washing, drying, and extrusion granulation to prepare standard recycled plastic granules, which are then reintroduced into the industrial production process as recycled raw materials.

[0051] The energy utilization pathways include two types: One type involves preparing low-value combustible components into RDF solid fuel, which is then sent to incineration power plants or industrial boilers to replace coal and achieve energy recovery. Another type involves feeding high-value plastics into an anaerobic pyrolysis unit to produce fuel oil and hydrogen through pyrolysis, thus achieving chemical energy recovery.

[0052] Existing technologies mostly adopt the traditional disposal method of direct incineration. This solution matches different utilization paths according to the value level of materials. High-value materials are recycled at the material level or as high-value chemicals, while low-value materials are recycled for energy, which greatly improves the comprehensive utilization rate of resources and the economic benefits of the project.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for the tiered treatment of lightweight materials from aged waste, characterized in that, Includes the following steps: S1. The coarse lightweight material obtained from the screening of aged garbage is sent to the magnetic separation process via a chain conveyor to remove ferromagnetic metal impurities from the material. Then it is sent to the crushing and loosening process to separate the entangled, agglomerated and mud-attached lightweight material. After that, it is sent to the kneading process for flexible grinding to peel off the mud and sand adhering to the surface, so that the lightweight material is formed into a loose material. S2. The loose material is fed into a multi-stage screening device. The vibrating screen of the multi-stage screening device is used to separate the material into fine material components, intermediate particle size components and large particle size lightweight components according to the particle size. The fine material components are separated as mud and sand enrichment or backfilled for reuse, while the intermediate particle size components and / or large particle size lightweight components are sent to subsequent processing. S3. The light components entering the subsequent processing are air-classified to remove impurities such as mud, sand, stones, glass, metal and high-density impurities, so as to obtain sortable light materials. S4. Adjust the moisture content and clean the surface of the sortable lightweight material obtained in step S3 to reduce the mud film and water film on the surface of the lightweight material and achieve photoelectric recognition conditions. S5. The lightweight material obtained in step S4 is sent to the photoelectric sorting equipment. Based on one or more of the identification results of material, color, shape, chlorine risk, and calorific value, the lightweight material is divided into high-value plastic components, low-value combustible components, chlorine-containing risk components and residual impurity components. S6. Send the high-value plastic components into the material utilization or chemical recycling path, send the low-value combustible components into the RDF preparation or incineration power generation process, and separately remove or carry out special harmless treatment of chlorine-containing risk components.

2. The method for tiered treatment of lightweight waste according to claim 1, characterized in that: In step S1, the crushing and loosening process employs one or more combinations of low-speed shearing, tearing, spreading, reverse spreading, or airflow loosening to break up films, strips of cloth, woven bags, and lightweight wooden materials without excessive crushing. In step S1, the crushing and loosening process simultaneously removes mud and sand, using friction and collision between the crushing parts and the screen surface, spreading parts, or cylinder wall to remove mud and sand adhering to the surface of the lightweight materials.

3. The method for tiered treatment of lightweight waste according to claim 1, characterized in that: In step S1, the magnetic separation process uses a suspended permanent magnet separator, which is mounted above the discharge end of the chain conveyor to adsorb and remove ferromagnetic impurities from the coarse and light materials. After the magnetic separation process, the coarse and light materials are first crushed by biaxial shearing to a particle size ≤100mm before being fed into the kneading equipment. The kneading equipment uses two sets of flexible kneading rollers that rotate in opposite directions at different speeds. The rollers are covered with a wear-resistant rubber lining so that the main body of the material remains intact during the kneading process, and only the surface-adhered impurities are peeled off. The material processed by the kneading equipment is then screened by a multi-stage screening equipment. The fine material obtained by screening consists of a particle size of less than 10 mm, an intermediate particle size consists of a particle size of 10 mm to 30 mm, and a large particle size lightweight component consists of a particle size of more than 30 mm. The multi-stage screening equipment uses a double-layer variable tilt angle vibrating screen.

4. The method for tiered treatment of lightweight waste according to claim 1, characterized in that: In step S2, intermediate particle size components are selected to enter the secondary air classification, return to the crushing and loosening process, or enter the RDF preparation process according to their mud content, plastic content, or moisture content.

5. The method for tiered treatment of lightweight materials from aged waste according to claim 1, characterized in that: Step S3 involves air separation and impurity removal, which includes primary air separation and secondary air separation. Large-diameter lightweight materials are sent to the primary air separation to separate heavy aggregates; medium-diameter lightweight materials are sent to the secondary air separation to remove fine sand and small-particle heavy impurities. The secondary air separation is used to separate lightweight plastics, films, cloth strips, paper, wood, and foam into layers.

6. The method for tiered treatment of lightweight materials from aged waste according to claim 5, characterized in that: In step S3, a circulating hot air system is also provided. The primary and secondary air separation systems share the circulating hot air system. The air separation airflow generated by the two-stage air separation equipment is recycled after dust removal and heating, so that the moisture content of large-diameter lightweight materials and medium-diameter lightweight materials is reduced to below 20%.

7. The method for tiered treatment of lightweight materials from aged waste according to claim 1, characterized in that: In step S4, the moisture content is controlled by one or more of the following methods: mechanical extrusion dehydration, centrifugal dehydration, hot air drying, waste heat drying, negative pressure dehumidification, air knife blowing, or friction cleaning.

8. The method for tiered treatment of lightweight waste according to claim 1, characterized in that: Before step S5, there is also a material distribution step, which uses a buffer hopper, star feeder, vibrating material distributor, pressure hood, flow stabilizing guide hood or high-speed conveyor belt to make the lightweight material enter the photoelectric recognition area in a single layer or low stacking state.

9. The method for tiered treatment of lightweight materials from aged waste according to claim 1, characterized in that: The multimodal photoelectric sorting process in step S5 uses at least two of the following for fusion recognition: line scanning AI visual recognition, near-infrared recognition, hyperspectral recognition, fluorescence recognition, and metal recognition. The recognition algorithm is trained based on a dedicated spectral database of lightweight waste. Hyperspectral recognition is used to distinguish PET, PE, PP, PVC, HDPE, LDPE, or other plastic materials. AI visual recognition is used to determine the material's shape, color, degree of contamination, or stacking status. Fluorescence recognition is used to identify aged plastics or fluorescent components. Metal recognition is used to remove metal impurities.

10. The method for tiered treatment of lightweight materials from aged waste according to claim 1, characterized in that: In step S5, PVC, CPVC, or other chlorine-containing components are identified and removed first, and the remaining materials are then sorted into high-value plastic components and low-value combustible components. The high-value plastic components include one or more of PP, PE, PET, HDPE, or LDPE, and are sent to recycling granulation, pyrolysis refining, gasification hydrogen extraction, or other chemical recycling pathways according to cleanliness, material purity, or degree of pollution. The low-value combustible components include one or more of wood, cloth strips, paper, low-value plastics, or foam, and are prepared into RDF after crushing, drying, blending, and compression molding.

Images