Plastic resource recycling treatment method, system and medium

Abstract

The application discloses a plastic resource recycling treatment method, system and medium, and relates to the technical field of plastic recycling treatment. The method comprises the following steps: obtaining waste plastic particle pollutant distribution and particle size state, placing the waste plastic particle pollutant distribution and particle size state in a controllable temperature cleaning medium, changing release conditions by using ladder temperature and intermittent mechanical disturbance; collecting medium pollutant concentration and particle surface release response at each stage, and converting the medium pollutant concentration and particle surface release response into a pollutant migration event sequence; determining a stage at which pollutants migrate from the inside of particles to the surface and the cleaning medium according to the interval between adjacent events, temperature and disturbance state, and reconstructing a pollutant migration path; matching infiltration temperature, disturbance intensity and medium flow direction according to the connection relationship between adjacent migration stages, performing migration promotion, pollutant removal and secondary migration promotion treatment, and obtaining decontaminated plastic particles. The technical problem that internal pollutants of waste plastic particles are difficult to remove fully and repeated cleaning efficiency is low is solved, and the technical effect of improving the fullness of pollutant removal and cleaning treatment efficiency is achieved.

Description

Technical Field

[0001] This invention targets waste plastic particles and implements phased decontamination treatment by adjusting cleaning conditions and based on the release state of pollutants, so as to achieve the cleaning, purification and resource reuse of waste plastic particles. It relates to the field of plastic recycling technology, and specifically to plastic resource recycling methods, systems and media. Background Technology

[0002] With the increasing use of plastic products, the resource recycling of waste plastics has become an important way to reduce the consumption of virgin plastics and reduce solid waste. In the process of waste plastic recycling, it is usually necessary to sort, crush, and wash the waste plastics to remove oil, adhesives, organic residues, and other impurities adhering to the plastic surface. However, some contaminants can enter the pores, cracks, or internal retention areas of the plastic particles. The release rate is affected by factors such as the type of plastic, particle size, degree of contamination, washing temperature, and mechanical intensity, resulting in differences in the removal process between surface and internal contaminants. Existing washing methods typically use fixed temperatures, fixed stirring intensities, and preset washing times to uniformly treat waste plastic particles, making it difficult to adjust washing conditions in a timely manner according to the actual release of contaminants. When the washing time is insufficient, the internal contaminants of the particles cannot be fully released and removed. Compensating by extending the washing time, increasing the temperature, or increasing the number of repeated washing cycles can easily lead to increased water and energy consumption, reducing the efficiency of waste plastic recycling. Therefore, existing technologies still suffer from the problem of insufficient removal of internal contaminants from waste plastic particles and low efficiency from repeated washing processes. Summary of the Invention

[0003] This application provides a method, system, and medium for the recycling and treatment of plastic resources, which solves the technical problems in the prior art where it is difficult to fully remove pollutants inside waste plastic particles and repeated washing leads to low treatment efficiency.

[0004] A first aspect of this application provides a method for the resource-based recycling and processing of plastics, the method comprising:

[0005] The initial distribution and particle size of pollutants in the waste plastic particles to be treated are obtained. The waste plastic particles are placed in a temperature-controlled cleaning medium, and the pollutant release conditions are changed sequentially with stepped temperature and intermittent mechanical disturbance. The changes in pollutant concentration in the cleaning medium and the pollutant release response on the surface of the waste plastic particles are collected simultaneously at each disturbance stage. The continuous response is converted into a sequence of pollution migration events including the release start time, peak time, decay time, and re-release time. Based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance states, the migration stages of pollutants from the internal retention area of ​​the particles to the surface release area and then to the cleaning medium are determined, and the pollutant migration path is reconstructed based on the continuity of each migration stage. Based on the connection relationship between the current migration stage and the next migration stage in the pollutant migration path, the corresponding immersion temperature, mechanical disturbance intensity, and cleaning medium flow direction are selected to continue the migration-promoting treatment of waste plastic particles in the internal migration stage, and to allow waste plastic particles in the surface release stage to enter the pollutant removal treatment. When a re-release event is detected, a secondary migration-promoting treatment is triggered to obtain plastic particles that have undergone path-based decontamination treatment.

[0006] A second aspect of this application provides a plastic resource recycling and processing system, the system comprising:

[0007] The status acquisition module acquires the initial distribution and particle size of pollutants in the waste plastic particles to be treated, places the particles in a temperature-controlled cleaning medium, and sequentially changes the pollutant release conditions with stepped temperature and intermittent mechanical disturbance. The event sequence construction module synchronously collects the changes in pollutant concentration in the cleaning medium and the pollutant release response on the surface of the waste plastic particles during each disturbance stage, converting the continuous response into a pollution migration event sequence including the release start time, peak time, decay time, and re-release time. The migration path reconstruction module reconstructs the migration path based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance conditions. In the dynamic state, the migration stages of pollutants are determined from the internal retention area of ​​the particles to the surface release area and then to the cleaning medium. The pollutant migration path is reconstructed based on the continuity of each migration stage. The decontamination treatment module selects the corresponding immersion temperature, mechanical disturbance intensity and cleaning medium flow direction according to the connection relationship between the current migration stage and the next migration stage in the pollutant migration path. This allows the waste plastic particles in the internal migration stage to continue to undergo migration-promoting treatment, and the waste plastic particles in the surface release stage to enter the pollutant removal treatment. When a re-release event is detected, a secondary migration-promoting treatment is triggered to obtain plastic particles that have undergone path-based decontamination treatment.

[0008] A third aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the plastic resource recycling method provided in this application.

[0009] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0010] First, the initial distribution and particle size of contaminants in the waste plastic particles to be treated are obtained. The particles are then placed in a temperature-controlled cleaning medium, and the contaminant release conditions are sequentially changed using stepped temperature and intermittent mechanical disturbance. Next, the changes in contaminant concentration in the cleaning medium and the contaminant release response on the surface of the waste plastic particles are simultaneously collected at each disturbance stage. The continuous response is converted into a contaminant migration event sequence including the release start time, peak time, decay time, and re-release time. Then, based on the time interval between adjacent contaminant migration events and their corresponding temperature and mechanical disturbance states, the migration stages of contaminants from the internal retention zone of the particles to the surface release zone and then back to the cleaning medium are determined, and the contaminant migration path is reconstructed based on the continuity of each migration stage. Finally, based on the connection between the current migration stage and the next migration stage in the contaminant migration path, the corresponding immersion temperature, mechanical disturbance intensity, and cleaning medium flow direction are selected. This allows the waste plastic particles in the internal migration stage to continue to undergo migration-promoting treatment, while the waste plastic particles in the surface release stage enter the contaminant removal treatment. A secondary migration-promoting treatment is triggered when a re-release event is detected, resulting in plastic particles that have undergone path-based decontamination treatment. This application solves the technical problem that it is difficult to fully remove pollutants from the inside of waste plastic particles in the prior art, and that repeated washing leads to low treatment efficiency, thereby achieving the technical effect of improving the fullness of pollutant removal and the efficiency of cleaning treatment of waste plastic particles. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the plastic resource recycling method provided in the embodiments of this application;

[0013] Figure 2 This is a schematic diagram of the reconstructed stages of the pollutant migration path provided in the embodiments of this application;

[0014] Figure 3 This is a schematic diagram of the structure of a plastic resource recycling system provided in an embodiment of this application.

[0015] Figure labeling: Status acquisition module 11, event sequence construction module 12, migration path reconstruction module 13, decontamination treatment module 14. Detailed Implementation

[0016] 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.

[0017] Example 1, as Figure 1 As shown, this application provides a method for the resource-based recycling and treatment of plastics, wherein the method includes:

[0018] The initial distribution and particle size of pollutants in the waste plastic particles to be treated are obtained. The waste plastic particles to be treated are placed in a temperature-controlled cleaning medium, and the pollutant release conditions are changed sequentially by step temperature and intermittent mechanical disturbance.

[0019] Specifically, the waste plastic particles to be treated are dispersed and imaged. The location and area of ​​contaminant coverage are determined based on the difference in spectral response between the contaminants on the particle surface and the clean plastic substrate. The equivalent particle size is calculated based on the particle profile, thus obtaining the initial distribution and particle size of the contaminants in the waste plastic particles. Based on the initial distribution and particle size, the type of cleaning medium, initial immersion temperature, number of temperature steps, target temperature and holding time for each temperature step, and the mechanical disturbance intensity and period corresponding to each temperature step are determined. The waste plastic particles to be treated are completely immersed in the temperature-controlled cleaning medium and maintained at the initial immersion temperature for a preset immersion time. After immersion, the particles are then subjected to a series of progressively increasing temperature steps. Temperature steps regulate the temperature of the cleaning medium. When the cleaning medium reaches the current temperature step and remains stable, alternating disturbance and settling are performed according to the corresponding mechanical disturbance intensity. After completing one or more disturbance cycles corresponding to the current temperature step, the temperature is raised to the next temperature step and intermittent mechanical disturbance is repeated, so that the waste plastic particles to be treated are in multiple disturbance stages formed by different combinations of temperature and mechanical disturbance in sequence. The temperature step number, actual temperature, disturbance start and end time, mechanical disturbance intensity and settling time of each disturbance stage are recorded in association to form a pollutant release condition sequence with a unified time reference. This provides a stage division basis for the synchronous collection of subsequent pollutant concentration changes in the cleaning medium and the pollutant release response on the surface of the waste plastic particles to be treated.

[0020] Furthermore, obtaining the initial distribution and particle size distribution of pollutants in the waste plastic particles to be treated includes:

[0021] The waste plastic particles to be treated are dispersed and spread so that they pass through the imaging detection area in a non-overlapping state. Multispectral images of the surface and contours of each particle are acquired. Based on the response differences between the characteristic bands of pollutants in the surface multispectral images and the bands of the clean plastic substrate, the pollutant coverage area on the surface of each particle is determined, and the equivalent particle size is determined based on the particle contour image. Using a single particle as a registration unit, the pollutant coverage area is mapped to the contour coordinates of the corresponding particle, forming an initial particle-level pollution distribution with pollutant coverage location, coverage area, and equivalent particle size. The spatial resolution of the pollutant coverage area is no greater than one-tenth of the equivalent particle size, so that subsequent pollutant migration events are correlated according to the initial particle-level location.

[0022] Preferably, before imaging detection, according to the material type of the waste plastic particles to be treated, uncontaminated plastic particles of the same type and plastic particles of the same type with the target pollutant are selected as clean plastic substrate calibration samples and pollutant calibration samples, respectively. Multispectral responses of the two types of calibration samples are collected under the same illumination intensity, imaging distance, and exposure time. From each imaging band, the band with the largest difference in response between the pollutant calibration sample and the clean plastic substrate calibration sample is selected as the pollutant characteristic band, and the band with stable response of the clean plastic substrate is selected as the clean plastic substrate band. The waste plastic particles to be treated are dispersed and laid in the imaging detection area according to a preset feed amount. The closed contour of each particle is extracted through the particle contour image. When any two closed contours contact or overlap, the corresponding particles are redispersed and imaged again until each particle forms an independent contour region. Dark field correction, brightness normalization, and noise filtering are performed on the surface multispectral image. The corrected surface multispectral image and the particle contour image are coordinate registered according to the same imaging field of view. For any pixel within the contour range of the i-th particle... Based on the response values ​​of the characteristic bands of pollutants Compared with the band response value of clean plastic substrate Calculate the band response difference of this pixel. ,in, , A positive number is set to prevent the denominator from being zero; the contamination discrimination threshold is determined based on the difference in band response distribution between the clean plastic substrate calibration sample and the contaminant calibration sample. Pixels not less than the pollution discrimination threshold are marked as polluted pixels. Adjacent polluted pixels are merged into connected regions, and isolated regions with an area smaller than the preset noise area are removed to obtain the pollutant coverage area of ​​the i-th particle. The projected area of ​​the i-th particle is calculated based on the number of pixels within the closed contour of the i-th particle and the actual size of a single pixel obtained through size calibration. and in accordance with Calculate the equivalent particle size of the i-th particle. Using the centroid of the i-th particle's outline as the local coordinate origin, and the major axis of the particle's outline as the first coordinate axis and the direction perpendicular to the major axis as the second coordinate axis, the polluted pixels within the pollutant coverage area are transformed from imaging coordinates to the local outline coordinates of the corresponding particle. The pollutant coverage area is calculated based on the product of the number of polluted pixels and the actual area of ​​a single pixel, thereby forming an initial particle-level pollution distribution that includes at least particle identification, pollutant coverage location, pollutant coverage area, and equivalent particle size. The actual pixel size within the imaging detection area is determined using a standard-size calibration component. And verify them one by one. If any particle does not meet the condition, the magnification of the corresponding imaging area is increased or the particle is re-examined individually until the spatial resolution of the pollutant-covered area is no greater than one-tenth of the equivalent particle size. Finally, the particle identifier, local contour coordinates, pollutant-covered area and equivalent particle size of each particle are associated and stored as initial data for subsequent association between pollutant migration events and particle-level initial positions.

[0023] Furthermore, the stepped temperature includes multiple temperature steps that increase sequentially, the holding time of each temperature step is not less than the duration of the corresponding disturbance stage, and the heating rate between adjacent temperature steps does not exceed 5℃ / min.

[0024] Specifically, based on the heat resistance temperature of the waste plastic particles to be treated, the stabilization temperature of the cleaning medium, and the temperature range required for pollutant release, the minimum temperature step T1 and the maximum temperature step T are determined. n Among them, the highest temperature step T n Below the lower of the material's heat resistance temperature and the cleaning medium's stable temperature, and between the lowest temperature step T1 and the highest temperature step T... n At least one intermediate temperature step is set between each temperature step, such that each temperature step satisfies T1 < T2 < ... < T nWhen heating from the current temperature step to the next temperature step, the actual temperature of the cleaning medium is obtained according to a preset sampling period. The ratio of the temperature difference between two adjacent sampling moments to the sampling time interval is determined as the actual heating rate. The heating output is adjusted to ensure that the actual heating rate does not exceed 5°C / min. When the actual temperature of the cleaning medium enters a preset temperature tolerance range centered on the current target temperature and remains within the preset temperature tolerance range for a preset stable time, it is determined that the cleaning medium has reached the current temperature step. The moment when the current temperature step is reached is taken as the start time of heat preservation, and the corresponding intermittent mechanical disturbance is initiated at this temperature step. The time interval from the start of the first mechanical disturbance at the current temperature step to the end of the last mechanical disturbance is determined as the duration of the corresponding disturbance stage. The duration includes the time between two adjacent mechanical disturbances. The settling time is set, and the holding time of the current temperature step is set to be no less than the duration of the disturbance stage, so that the corresponding disturbance stage is always completed under stable temperature conditions. During the holding process, the actual temperature of the cleaning medium is continuously monitored. When the actual temperature exceeds the preset temperature tolerance range, the current disturbance stage and its duration are paused. The temperature of the cleaning medium is adjusted to re-enter the preset temperature tolerance range and remain stable before continuing to perform the remaining intermittent mechanical disturbance. After all the mechanical disturbances corresponding to the current temperature step are completed and the preset holding time is reached, the next temperature step is entered at a heating rate of no more than 5℃ / min until the disturbance stage corresponding to the highest temperature step is completed. The target temperature, actual temperature, heating rate, holding start and end time, and start and end time of the corresponding disturbance stage are recorded in chronological order for each temperature step.

[0025] The changes in pollutant concentration in the cleaning medium and the release response of pollutants on the surface of the waste plastic particles to be treated are collected simultaneously at each disturbance stage. The continuous response is converted into a sequence of pollution migration events including the release start time, peak time, decay time and re-release time.

[0026] Specifically, using the start time of each disturbance stage as a unified time reference, the concentration of pollutants in the cleaning medium and the release response of pollutants on the surface of the waste plastic particles to be treated are acquired synchronously according to the same sampling period. The collected data are correlated with the temperature step number, actual temperature, mechanical disturbance state, and sampling time of the corresponding disturbance stage. Outlier removal, missing value imputation, and smoothing filtering are performed on the two types of continuous responses within the same disturbance stage. The average response within a preset time window before the start of the disturbance stage is used as the stage baseline. The difference between the actual response at each sampling time and the stage baseline is determined as the corresponding relative response change, forming a cleaning medium pollutant concentration change curve and a waste plastic particle surface pollutant release response curve with a unified time axis. The direction and sequence of change of the two types of responses are detected sequentially along the unified time axis. When the release response of pollutants on the surface of the waste plastic particles to be treated changes from a stable state to a continuous increase, and the concentration of pollutants in the cleaning medium subsequently changes in the same direction, the surface pollutant release response is considered to have started to rise continuously. The time of release is marked as the release start time; when the change in the surface contaminant release response reaches a local maximum during the continuous rise, and the contaminant concentration in the cleaning medium continues to rise within the corresponding lag time, the time corresponding to the local maximum position is marked as the peak time; when the surface contaminant release response changes from rising to continuously weakening, and the contaminant concentration in the cleaning medium simultaneously enters a decreasing or stable state, the start time that satisfies the weakening condition is marked as the decay time; after the decay time, the two types of responses continue to be monitored, and when the surface contaminant release response changes from a stable or weakening state to a continuous rise again, and the contaminant concentration in the cleaning medium shows a corresponding lag-induced rise again, the start time of this renewed rise is marked as the re-release time; the sequentially associated release start time, peak time, decay time, and re-release time, along with the corresponding disturbance stage number, temperature, and mechanical disturbance state, are encapsulated into a contaminant migration event, and arranged according to the order of occurrence of each contaminant migration event to form the contaminant migration event sequence.

[0027] Furthermore, the changes in pollutant concentration in the cleaning medium and the release response of pollutants from the surface of the waste plastic particles to be treated are collected simultaneously at each disturbance stage, including:

[0028] Waste plastic particles to be treated are grouped according to particle size range and loaded into multiple cleaning chambers with independent inlet and outlet liquid channels, forming particle clusters in each cleaning chamber. Pollutant concentration sensors are installed upstream and downstream of the particle clusters in each cleaning chamber, and surface pollutant release detection units facing the particle clusters are installed in the cleaning chambers. During each disturbance stage, the pollutant concentration of the cleaning medium upstream and downstream of each cleaning chamber and the pollutant release response of the surface of the waste plastic particles to be treated output by the release detection units are collected simultaneously. The change in pollutant released from the particle clusters into the cleaning medium is determined by the difference in pollutant concentration between the two sides of the cleaning medium, and the release start, peak value and decay process of the corresponding particle clusters are determined by the time change of the release response on the particle surface.

[0029] Preferably, multiple non-overlapping and continuously connected particle size ranges are set according to the equivalent particle size of the aforementioned waste plastic particles to be treated. Waste plastic particles within the same particle size range are allocated to the same cleaning chamber, and each cleaning chamber is assigned a corresponding particle size group identifier. Particle clusters are formed in each cleaning chamber according to the same particle loading mass, cleaning medium volume, and particle filling height to reduce the impact of loading differences on the pollutant release response. Each cleaning chamber is equipped with independent inlet and outlet channels. No cleaning medium exchange occurs between adjacent cleaning chambers. The upstream and downstream of the particle clusters are determined according to the actual flow direction of the cleaning medium, and detection devices are installed upstream and downstream respectively. A pollutant concentration sensor for a target pollutant is used. Before formal data collection, the upstream and downstream pollutant concentration sensors are zero-calibrated using a cleaning medium that has not come into contact with the waste plastic particles to be treated. Multiple standard solutions with known pollutant concentrations are used for range calibration to establish a calibration relationship between the sensor output value and the actual pollutant concentration. Simultaneously, a temperature compensation relationship is established based on the detection results of the standard solutions at each temperature step to correct the influence of temperature gradients on the concentration detection results. When the waste plastic particles to be treated are not loaded, the cleaning medium flows through the corresponding cleaning chamber at a preset flow rate. The medium transport lag time of the cleaning chamber is determined based on the time required for the upstream concentration change to be transmitted downstream. Where j represents the cleaning chamber number; during formal data acquisition, the start time of each disturbance stage is used as a unified time reference, and the first sample is acquired synchronously according to the same sampling period. upstream contaminant concentration in the cleaning chamber Downstream pollutant concentration Cleaning medium flow rate The output value of the surface contaminant release detection unit is used, and the upstream and downstream contaminant concentrations are time-aligned according to the media transmission lag time. The change in contaminant concentration in the cleaning medium caused by the j-th particle group at time t is determined to be... The mass change rate of pollutants released from the particle group into the cleaning medium at the corresponding time is determined, and the pollutant release change amount at the corresponding disturbance stage is obtained by accumulating the mass change rate over time during the disturbance stage. In one embodiment, the surface pollutant release detection unit adopts a multispectral detection method oriented towards the particle group. It acquires particle group surface images through the transparent detection area of ​​the cleaning chamber, extracts the particle surface spectral response corresponding to the aforementioned pollutant characteristic bands, uses the average particle surface spectral response before the start of the current disturbance stage as the stage baseline, calculates the degree of change of particle surface spectral response relative to the stage baseline at each sampling time, and uses the average response change of each effective particle in the particle group detection area as the surface pollutant release response of the waste plastic particles to be treated. The pollutant concentration change, pollutant release change amount, and surface pollutant release response obtained at the same sampling time are associated and stored with the corresponding cleaning chamber number, particle size group identifier, temperature step number, and mechanical disturbance state to form synchronous response data for each disturbance stage. Based on the time change of the surface pollutant release response from stable to rising, reaching a local peak, and from peak to decay, the release initiation process, peak process, and decay process of the corresponding particle group are determined respectively.

[0030] Furthermore, the continuous response is transformed into a sequence of contamination migration events, including the release start time, peak time, decay time, and re-release time, comprising:

[0031] The changes in pollutant concentration in the cleaning medium and the release response of pollutants from the surface of the waste plastic particles to be treated are time-aligned to determine the change process of the two types of responses relative to the baseline of the corresponding disturbance stage. After the release response of pollutants from the surface of the waste plastic particles to be treated, which indicates the target pollutant leaving the particle surface, increases, it is detected whether the pollutant concentration in the cleaning medium changes in the same direction within a preset lag time. The changes in the release response of the waste plastic particles to be treated and the changes in the pollutant concentration in the cleaning medium that satisfy the sequential relationship are associated as a cross-interface migration event, and the time interval between the two is determined as the corresponding migration lag segment. After the cross-interface migration event ends, if the release response of the waste plastic particles to be treated increases again and the pollutant concentration in the cleaning medium changes again with a corresponding lag, the recurring response is associated as a subsequent cross-interface migration event. A pollution migration event sequence is formed according to the occurrence order of each cross-interface migration event and its migration lag segment.

[0032] Preferably, outlier removal and smoothing are performed on the synchronously collected changes in the concentration of pollutants in the cleaning medium and the release response of pollutants from the surface of the waste plastic particles to be treated. The changes in the concentration of pollutants in the cleaning medium are time-corrected based on the aforementioned medium transport lag time. The corrected changes in the concentration of pollutants in the cleaning medium and the surface pollutant release response are then interpolated to a unified time axis using the same sampling period. For each disturbance stage, two types of responses are extracted from a preset baseline time window before the start of that disturbance stage. The mean values ​​of the corresponding responses are determined as the baseline for the medium concentration stage and the baseline for the surface release stage, respectively. The surface pollutant release detection signal and the target pollutant leaving the particle are determined through a pre-performed pollutant surface release calibration. The response direction between particle surfaces is determined as follows: when the original detection signal increases as the target contaminant leaves the particle surface, the difference between the original detection signal and the baseline of the surface release stage is defined as the surface contaminant release response; conversely, when the original detection signal decreases as the target contaminant leaves the particle surface, the difference between the baseline of the surface release stage and the original detection signal is defined as the surface contaminant release response. This ensures that the increase in the surface contaminant release response uniformly represents the increase in the amount of target contaminant leaving the particle surface per unit time. The difference between the contaminant concentration in the cleaning medium at each sampling time and the baseline of the medium concentration stage is used to characterize the relative change in medium concentration. This yields the relationship between the surface contaminant release response and the contaminant concentration in the cleaning medium. The changes during the corresponding disturbance phase; pre-contaminant release calibration tests were conducted for different particle size ranges, cleaning medium flow rates, and mechanical disturbance intensities. The time interval from the start of the surface contaminant release response after the target contaminant leaves the particle surface to the corresponding increase in the contaminant concentration in the cleaning medium was statistically analyzed. The sum of the upper limit of each calibration time interval and the preset time margin was used as the preset lag time under the corresponding treatment conditions. The preset lag time characterizes the maximum allowable response time for the target contaminant to leave the particle surface and cross the solid-liquid interface into the cleaning medium, excluding the already corrected cleaning medium transport lag time; the surface contaminant release response was detected along the unified time axis. When the surface contaminant release response changes from a preset fluctuation range of the surface release stage baseline to a continuous increase, it is determined that the target contaminant begins to leave the particle surface, and the corresponding time is taken as the candidate release start time. Starting from the candidate release start time, the change in the concentration of contaminants in the cleaning medium is retrieved within the preset lag time. When the concentration of contaminants in the cleaning medium changes continuously in the upward direction, the time when the corresponding change condition is first met is determined as the medium response time. The time interval between the candidate release start time and the medium response time is determined as the migration lag segment. The current increase in the surface contaminant release response and the lag increase in the concentration of contaminants in the cleaning medium are associated as a cross-interface migration event.If no corresponding increase in the concentration of contaminants in the cleaning medium is detected within the preset lag time, the current increase in the surface contaminant release response is marked as a surface release change to be confirmed, and it is not considered a separate cross-interface migration event. For cross-interface migration events that have already occurred, the release start time, peak time, and decay time are marked according to the order in which the surface contaminant release response begins to rise continuously, the degree of change reaches a local peak, and the peak turns into a continuous weakening. When both the surface contaminant release response and the concentration of contaminants in the cleaning medium fall back to the preset fluctuation range of the corresponding stage baseline and remain stable for a preset time, the cross-interface migration event is determined to have ended. During the decay of the cross-interface migration event... After a certain point, detection continues along a unified time axis. If the surface pollutant release response, indicating the target pollutant leaving the particle surface, shows a sustained increase again, and the pollutant concentration in the cleaning medium shows a delayed increase again within the corresponding preset lag time, then the two types of correlated responses that reappear are identified as subsequent cross-interface migration events. The release start time of the subsequent cross-interface migration event is simultaneously marked as the re-release time of the previous cross-interface migration event. The release start time, peak time, decay time, re-release time, migration lag segment, temperature step, and mechanical disturbance state corresponding to each event are sequentially ordered to form the pollution migration event sequence.

[0033] Furthermore, the change in the surface release response of the waste plastic particles to be treated, which satisfies the aforementioned sequential relationship, is correlated with the change in the concentration of contaminants in the cleaning medium as a single cross-interface migration event, including:

[0034] The release response of pollutants on the surface of the waste plastic particles to be treated and the rate and acceleration of change of pollutant concentration in the cleaning medium are calculated separately. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated increases from below a first release threshold to above the first release threshold, and the acceleration changes from negative to positive and continues for a first set time, the release start time is determined. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated reaches a local maximum and the acceleration changes from positive to negative, and the rate of change of pollutant concentration in the cleaning medium exceeds the medium response threshold within a preset lag time after the release start time, the time corresponding to the local maximum is determined as the peak time. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated is below a second release threshold and the acceleration remains less than zero or below a second acceleration threshold, and the rate of change of pollutant concentration in the cleaning medium is less than zero and continues for a preset decay duration, the decay time is determined. After the decay time, if the acceleration of the release response of pollutants on the surface of the waste plastic particles to be treated changes from negative to positive again and continues for a third set time, and the rate of change exceeds the first release threshold, and the pollutant concentration in the cleaning medium exceeds the medium response threshold again within a preset lag time, then the re-release time is determined.

[0035] Preferably, the release response of pollutants from the surface of the waste plastic particles to be treated after time alignment and smoothing is denoted as... The change in the concentration of contaminants in the cleaning medium is recorded as The sampling time interval between adjacent sampling times is denoted as For the k-th sampling time, according to and Calculate the rate of change and acceleration of change of the surface contaminant release response, and follow the... and The rate of change and acceleration of change of contaminant concentration in the cleaning medium are calculated separately. For cases where either the preceding or following sampling point is missing at either end of a continuous response, one-sided difference calculation is performed using two adjacent sampling points. The baseline time window before the start of the corresponding disturbance phase is extracted, and statistics are compiled within this baseline time window. , and The mean and standard deviation of the baseline change rate of the surface contaminant release response are used to determine the first release threshold. The sum of the mean of the baseline change rate and the standard deviation of the baseline change rate at a first preset multiple is determined as the second release threshold. The sum of the mean of the baseline change rate and the standard deviation of the baseline change rate at a second preset multiple is determined as the second release threshold. The first preset multiple is greater than the second preset multiple, so that the first release threshold is higher than the second release threshold. The lower limit of the acceleration distribution of the baseline change in the surface contaminant release response, which is used to characterize a significant negative change, is determined as the second acceleration threshold. The second acceleration threshold is less than zero. The mean and standard deviation of the baseline change rate of the contaminant concentration in the cleaning medium are used to determine the standard deviation of the baseline change rate at a third preset multiple. The sum of the quasi-errors is determined as the media response threshold; based on the duration of continuous change in the rate or acceleration sign caused by noise within the stage baseline time window, a first set time and a third set time are determined respectively, such that both the first set time and the third set time are greater than the maximum continuous duration of the corresponding noise fluctuation; the duration for which the rate of change of the cleaning medium contaminant concentration is continuously less than zero due to noise within the stage baseline time window is statistically analyzed, and the sum of the maximum value of the duration and a sampling time interval is determined as the preset attenuation duration, so that the decrease in the rate of change of concentration caused by short-term detection fluctuations will not be judged as effective attenuation; starting from the start time of the current disturbance stage, each sampling time is traversed sequentially, when The release threshold changes from being below the first release threshold to being not below the first release threshold, and When the value changes from negative to positive and remains positive for a first set time, the sampling moment that first meets the above conditions will be determined as the release start moment. From the release start time Continue iterating until... The rate of change is greater than that of adjacent sampling times, thus forming a local maximum. When the value changes from positive to negative, the sampling time is taken as the candidate peak time, and the self-release start time is used. Detection within the preset delay time starting from the start ,when When the media response threshold is exceeded, it is confirmed that the surface contaminant release response and the change in contaminant concentration in the cleaning medium constitute a cross-interfacial migration relationship, and the candidate peak time is determined as the peak time. and will release the start time The time interval between the moment when the rate of change of contaminant concentration in the cleaning medium first exceeds the media response threshold is defined as the migration hysteresis period; if within the preset hysteresis period... If the response threshold of the medium is not exceeded, the change in the surface contaminant release response will not be recognized as a cross-interface migration event; at the peak time The testing continued afterward, when Below the second release threshold, and If the acceleration is less than zero or below the second acceleration threshold at multiple consecutive sampling times, and When the duration of a value less than zero and continuously less than zero reaches the preset attenuation duration, the sampling moment that first simultaneously satisfies the above conditions is determined as the attenuation moment. ; at the decay time Then continue iterating, when It changes from a negative value to a positive value again and remains positive for a third set period of time, and If the first release threshold is exceeded again, the corresponding sampling time will be used as a candidate release time, and detection will be performed within a preset lag time starting from the candidate release time. ,when If the medium response threshold is exceeded again, the candidate release time will be determined as the release time. ; will release the start time Peak time Decay time Release time again The corresponding migration lag segment is associated with the current temperature step, mechanical disturbance state, and particle size group identifier to form a cross-interface migration event record. If the conditions for re-release are not met after the decay time, no re-release time marker is generated, and the cross-interface migration event ends after both types of responses fall back to the corresponding stage baseline fluctuation range.

[0036] Based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance states, the migration stages of pollutants from the internal retention zone of particles to the surface release zone and then to the cleaning medium are determined, and the pollutant migration path is reconstructed based on the continuity of each migration stage.

[0037] Specifically, multiple contaminant migration events corresponding to the same cleaning chamber and the same particle size group are sorted according to the release start time, and the decay time of the i-th contaminant migration event is denoted as... Let the release start time of the (i+1)th adjacent pollution migration event be denoted as . and in accordance with Calculate the time interval between two adjacent contamination migration events; conduct pre-release tests for different plastic material types, particle size ranges, temperature steps, and mechanical disturbance intensities, and statistically analyze the maximum time interval between adjacent contamination migration events formed by the continuous release of the same batch of contaminants. The sum of this maximum time interval and a preset time margin is determined as the event continuity threshold under the corresponding treatment conditions. For each contamination migration event, the time interval from the start of the current disturbance stage to the surface contaminant release response reaching the release initiation condition is determined as the candidate internal migration interval; the time interval from the release initiation moment to the moment when the rate of change of the contaminant concentration in the cleaning medium first exceeds the media response threshold is determined as the surface release stage; the time interval from the moment when the rate of change of the contaminant concentration in the cleaning medium first exceeds the media response threshold to the moment when the contaminant concentration in the cleaning medium falls back to the baseline fluctuation range of the corresponding stage is determined as the cleaning media migration stage. For adjacent i-th and i+1-th contamination migration events, when they belong to the same cleaning chamber and the same particle size group, the time interval... If the two events are not greater than the corresponding event continuity threshold, and there is no particle replacement, cleaning medium replacement, or cleaning process termination between them, and the temperature and mechanical disturbance states corresponding to the (i+1)th contamination migration event belong to the current disturbance state or the next preset disturbance state within the same processing cycle, then the two contamination migration events are considered to have migration continuity. When the i-th contamination migration event enters the decay state, both the particle surface contaminant release response and the cleaning medium contaminant concentration are within the stage baseline fluctuation range. However, after the temperature step increases, the mechanical disturbance recovers, or the mechanical disturbance intensity increases, the (i+1)th contamination migration event... When the events occur within the continuity threshold, the time interval between the decay time of the i-th contamination migration event and the release start time of the (i+1)-th contamination migration event is backtracked and marked as the internal migration stage, which characterizes the contaminants continuing to migrate from the internal retention area of ​​the particle to the particle surface after the external response temporarily weakens; the time interval between the release start time of the (i+1)-th contamination migration event and the corresponding media response time is marked as the surface release stage, which characterizes the release of contaminants reaching the particle surface at the solid-liquid interface; the period from the media response time to the point where the contaminant concentration in the cleaning medium enters decay and falls back to the stage baseline fluctuation is defined as the period from the stage baseline. The time interval within the range is marked as the cleaning medium migration stage, used to characterize the migration of contaminants that have crossed the solid-liquid interface with the cleaning medium and are carried away from the particle surface. The internal migration stage, surface release stage, and cleaning medium migration stage within the same continuous treatment cycle are sequentially connected according to time sequence. Each migration stage is associated with its corresponding start and end times, temperature steps, mechanical disturbance state, migration lag, and contaminant concentration change. A stage connection is established when the end and start times of two adjacent migration stages are consecutive and the migration direction satisfies the sequence "particle internal retention area - surface release area - cleaning medium". For consecutive re-release events, new internal migration stages, surface release stages, and cleaning medium migration stages are added after the previous cleaning medium migration stage according to the same rules, until no subsequent contaminant migration event is detected within the event continuity threshold, thus forming a contaminant migration path arranged according to the contaminant migration location and occurrence time. When the time interval between adjacent contaminant migration events exceeds the event continuity threshold, or when particle replacement, cleaning medium replacement, or treatment process termination occurs, the stage connection between the two events is broken, and the subsequent contaminant migration event is taken as the starting point of a new contaminant migration path.

[0038] like Figure 2As shown, contamination migration events corresponding to the same cleaning chamber and the same particle size group are sorted according to the release start time. Adjacent first contamination migration events E1 and E2 are used as the continuity judgment objects. The first contamination migration event E1 includes the release start time ts1, peak time tp1, and decay time td1; the second contamination migration event E2 includes the release start time ts2, peak time tp2, and decay time td2. The release start time ts2 of the second contamination migration event E2 is simultaneously determined as the re-release time tr1 of the first contamination migration event E1. The relationship between ts2 and td1 is calculated. The interval between adjacent events is Δt1. When the first contamination migration event E1 and the second contamination migration event E2 belong to the same cleaning chamber and the same particle size group, the interval between adjacent events Δt1 is not greater than the corresponding event continuity threshold, and the temperature steps and mechanical disturbance states corresponding to the two contamination migration events belong to the same processing cycle, it is determined that the two contamination migration events meet the continuity condition, and the connection relationship between the corresponding migration stages is established. The time interval from the start of the current disturbance stage to the release start time ts1 of the first contamination migration event E1 is marked as the first internal migration stage I1, and the time interval from the release start time ts1 to the first medium response time tc1 is marked as the first internal migration stage I1. The time interval between the first media response time tc1 and the first event end time te1 when the contaminant concentration of the cleaning medium falls back to the stage baseline fluctuation range is marked as the first cleaning medium migration stage L1; when the second contaminant migration event E2 is detected after the first contaminant migration event E1 decays, the time interval between the decay time td1 and the release start time ts2 is marked as the second internal migration stage I2, and the time interval between the release start time ts2 and the second media response time tc2 is marked as the second surface release stage S2. The time interval between 2 and the end time te2 of the second event is marked as the second cleaning medium migration stage L2. Each migration stage is connected in the time sequence of "I1-S1-L1-I2-S2-L2" to form a pollutant migration path from the internal retention area of ​​the particle to the surface release area and then to the cleaning medium. When adjacent pollutant migration events do not belong to the same cleaning chamber or the same particle size group, the interval between adjacent events exceeds the event continuity threshold, or the temperature and mechanical disturbance states do not belong to the same treatment cycle, the connection between the two pollutant migration events is broken, and the latter pollutant migration event is taken as the starting point of the new pollutant migration path.

[0039] Based on the connection between the current migration stage and the next migration stage in the pollutant migration path, the corresponding immersion temperature, mechanical disturbance intensity and cleaning medium flow direction are selected to allow waste plastic particles in the internal migration stage to continue to undergo migration-promoting treatment, and waste plastic particles in the surface release stage to enter the pollutant removal treatment. When a re-release event is detected, a secondary migration-promoting treatment is triggered to obtain plastic particles that have undergone path-based decontamination treatment.

[0040] Specifically, a correspondence between migration stages and cleaning control parameters is established in advance according to the type of plastic material, particle size range, and type of contaminants. The cleaning control parameters include the immersion temperature, mechanical disturbance intensity, disturbance duration, cleaning medium flow direction, and medium flow rate corresponding to each temperature step. The maximum allowable immersion temperature below the softening or deformation temperature of the plastic material, the maximum allowable mechanical disturbance intensity that will not cause particle breakage, and the allowable medium flow rate of the cleaning chamber are set as upper limits for these parameters. The last confirmed migration stage in the real-time updated contaminant migration path is determined as the current migration stage, and the established parameters are used according to the migration stages that follow. The stage connection relationship determines the next migration stage; when both the current migration stage and the next migration stage are internal migration stages, it is determined that the contaminant is still retained inside the particle and the current release conditions are insufficient. The current temperature step is increased by a preset temperature gradient, and the current mechanical disturbance intensity is maintained within the range not exceeding the maximum allowable mechanical disturbance intensity. Simultaneously, the duration of the current disturbance stage is extended, allowing the cleaning medium to continue wetting the particle pores and crack areas until a surface contaminant release response is detected, reaching the release initiation condition. Wherein, if the wetting temperature after increasing by a preset temperature gradient exceeds the maximum allowable wetting temperature, the wetting temperature is maintained at the maximum allowable wetting temperature. Temperature is used to continue promoting migration by extending the duration of the disturbance phase. When the current migration phase is the internal migration phase and the next migration phase is the surface release phase, the current wetting temperature is maintained within the preset temperature tolerance range of the corresponding temperature step. Intermittent mechanical disturbance is continued according to the corresponding mechanical disturbance intensity, and the cleaning medium is kept in a low-flow circulation state to avoid premature large-scale replacement of contaminants before they reach the particle surface. When the surface contaminant release response is detected to meet the release initiation conditions, and the current migration phase is confirmed to have entered the surface release phase, the flow direction of the cleaning medium is adjusted to flow from the inlet side with low contaminant concentration through the particle group to the outlet side. The particle group is mechanically disturbed in the positive direction of removal according to the corresponding surface release disturbance intensity, so that the pollutants reaching the particle surface are removed from the solid-liquid interface and migrate towards the liquid outlet with the cleaning medium; when the current migration stage is the surface release stage and the next migration stage is the cleaning medium migration stage, the positive removal direction and the corresponding medium flow rate are maintained, and the upstream and downstream cleaning medium pollutant concentrations are continuously collected. The amount of pollutant removed is determined by the concentration difference on both sides and the medium flow rate. After the downstream pollutant concentration enters the decay stage from the peak, the mechanical disturbance intensity is gradually reduced until the cleaning medium pollutant concentration falls back to the baseline fluctuation range of the corresponding stage, thus completing the current pollutant removal treatment;After the pollutant removal treatment, a preset observation time is maintained. If the acceleration of the change in the pollutant release response on the surface of the waste plastic particles to be treated changes from negative to positive again and continues for a third preset time, and the rate of change exceeds the first release threshold again, and the pollutant concentration in the cleaning medium exceeds the media response threshold again within a preset lag time, then a re-release event is confirmed and a secondary migration-promoting treatment is triggered. The direction of the cleaning medium flow is switched from the forward removal direction of the previous stage to the reverse flushing direction. The mechanical disturbance intensity is adjusted to 1.2 to 2 times the mechanical disturbance intensity of the previous stage, and reverse flushing and intermittent mechanical disturbance are performed within the maximum allowable mechanical disturbance intensity range to ensure that the original forward flow conditions did not fully impregnate the particles. The contact area and pore area of ​​the moistened particles are again subjected to the cleaning medium. During the secondary migration-promoting treatment, the pollutant migration path is continuously updated according to the aforementioned pollution migration event identification rules. When the internal migration stage, surface release stage, and cleaning medium migration stage are identified again, the corresponding migration-promoting treatment and pollutant removal treatment are executed sequentially. When no re-release event is detected within the preset observation time, and both the surface pollutant release response and the pollutant concentration in the cleaning medium remain within the baseline fluctuation range of the corresponding stage, it is determined that the current particle size group has reached the decontamination termination condition. Heating and mechanical disturbance are stopped, and the plastic particles in the cleaning chamber are separated from the cleaning medium to obtain plastic particles that have undergone path-based decontamination treatment.

[0041] Furthermore, after selecting the immersion temperature, mechanical disturbance intensity, and cleaning medium flow direction according to the pollutant migration path, the method further includes: when no effective release response meeting the criteria occurs in two consecutive migration stages, the corresponding temperature step is increased by a preset gradient and the duration of the current disturbance stage is extended.

[0042] Specifically, the response determination results corresponding to two adjacent disturbance stages in the pollutant migration path are compared. The effective release response that meets the criteria refers to the release response of the surface pollutants of the waste plastic particles to be treated reaching the release initiation condition, and the rate of change of the pollutant concentration in the cleaning medium exceeding the medium response threshold within a preset lag time after the corresponding release initiation time. This allows the surface pollutant release response and the change in the pollutant concentration in the cleaning medium to be associated as a response of a cross-interface migration event. When no effective release response is formed in two consecutive migration stages, a temperature step increase and disturbance stage extension control are triggered. In either migration stage, if the surface pollutant release response does not reach the release initiation condition, or if the surface pollutant release response reaches the release initiation condition but the rate of change of the pollutant concentration in the cleaning medium does not exceed the medium response threshold within the preset lag time, it is determined that no effective release response meeting the criteria has occurred in that migration stage. Based on the material type, particle size range, and current contaminant coverage of the waste plastic particles to be treated, a preset temperature gradient, preset extension time, maximum allowable wetting temperature, and maximum allowable disturbance time are obtained from a pre-established correspondence of migration-promoting parameters. The preset temperature gradient is determined through a pre-release test of waste plastic particles of the same material type and particle size range, and is the minimum temperature increment that can promote the migration of contaminants from inside the particles to the particle surface without causing softening or deformation of the plastic particles. The preset extension time is determined by the sum of the maximum value of the time required for the first effective release response meeting the criteria after the temperature increases from the preset temperature gradient in the pre-release test and a preset time margin. The target temperature of the current temperature step is denoted as... The preset temperature gradient is denoted as The maximum permissible immersion temperature is denoted as ,according to Determine the adjusted target temperature The cleaning medium is heated from its current temperature to the adjusted target temperature at a rate not exceeding 5℃ / min. During the heating process, the duration of the current disturbance phase is paused. Once the actual temperature of the cleaning medium enters and stabilizes within the preset temperature tolerance range centered on the adjusted target temperature, the intermittent mechanical disturbance and duration timing are resumed. The sum of the original duration of the current disturbance phase and the preset extension time is determined as the adjusted disturbance phase duration, ensuring that the adjusted disturbance phase duration does not exceed the maximum allowable disturbance time. During the extended disturbance phase, the original mechanical disturbance intensity and the current cleaning medium flow direction remain unchanged, and the release response of pollutants from the surface of the waste plastic particles to be treated and the cleaning process are continuously collected. When the concentration of pollutants in the cleaning medium changes, and the release response of pollutants on the surface of the waste plastic particles to be treated reaches the release initiation condition, and the rate of change of the concentration of pollutants in the cleaning medium exceeds the media response threshold within a preset lag time after the corresponding release initiation time, a valid release response that meets the criteria is determined to have occurred. The current temperature rise and disturbance phase extension control ends, the corresponding response is associated as a new cross-interface migration event, and the treatment is switched to the pollutant removal treatment corresponding to the surface release phase according to the updated pollutant migration path. If no valid release response that meets the criteria occurs at the end of the adjusted disturbance phase, the current adjustment cycle ends, and the decision to enter the next treatment cycle is determined by combining the maximum allowable immersion temperature and the maximum allowable disturbance time. When the cleaning medium has reached the maximum allowable immersion temperature, the temperature step will not be increased further. Instead, the current disturbance stage will be extended for the preset extension time, and the extension will stop after the maximum allowable disturbance time is reached. This is to avoid continuous internal migration judgments that could lead to a continuous increase in the cleaning medium temperature or processing time. The number of migration stages that have not met the criteria for a valid release response, the adjusted target temperature, the actual heating rate, the preset extension time, the adjusted disturbance stage duration, and the valid release response judgment results will be written into the corresponding contaminant migration path as the basis for subsequent selection of immersion temperature, mechanical disturbance intensity, and cleaning medium flow direction.

[0043] Furthermore, the secondary migration-promoting process triggered when the re-release event is detected includes: switching the flow direction of the cleaning medium to reverse flushing and increasing the intensity of mechanical disturbance to 1.2 to 2 times that of the previous stage.

[0044] Specifically, after the previous cross-interface migration event enters a decay state, the release response of pollutants on the surface of the waste plastic particles to be treated and the change in pollutant concentration in the cleaning medium are continuously collected. When the acceleration of the change in the surface pollutant release response changes from negative to positive again and continues for a third set time, and the rate of change exceeds the first release threshold again, and the rate of change of the pollutant concentration in the cleaning medium exceeds the medium response threshold again within a preset lag time, a re-release event is confirmed. The mechanical disturbance intensity of the previous migration stage is recorded. The event release intensity was calculated based on the peak change rate of the surface contaminant release response and the peak change rate of the contaminant concentration in the cleaning medium during the previous interfacial migration event and the re-release event, respectively. The ratio of the event release intensity of the re-release event to the event release intensity of the previous interfacial migration event was limited to between 0 and 1 to obtain the re-release intensity ratio. ,according to Determine the disturbance amplification factor The disturbance amplification factor is kept between 1.2 and 2; the maximum permissible mechanical disturbance intensity that will not cause the plastic particles to break or deform is determined in advance based on the type of plastic material and particle size range. and increase the mechanical disturbance intensity of the previous migration stage. Not greater than After triggering the secondary migration process, according to Determine the target mechanical disturbance intensity for the secondary migration-promoting treatment This ensures that the target mechanical disturbance intensity is 1.2 to 2 times that of the previous migration stage, but does not exceed the maximum allowable mechanical disturbance intensity. When switching the cleaning medium flow direction, the current forward-flowing medium flow rate is gradually reduced to zero. After the flow pressure in the cleaning chamber stabilizes, the inlet channel of the previous migration stage is switched to the outlet channel, and the outlet channel of the previous migration stage is switched to the inlet channel. Then, the cleaning medium flow rate is gradually increased to the preset reverse flushing flow rate, thus forming a cleaning medium flow direction opposite to that of the previous migration stage. When the reverse flushing flow rate reaches a stable state, the mechanical disturbance intensity is reduced from... Gradually improve to The process involves intermittent mechanical disturbances performed according to the aforementioned disturbance cycle. During the secondary migration-promoting treatment, the current wetting temperature is maintained below the maximum allowable wetting temperature. This allows the reverse-flowing cleaning medium to enter the particle contact area, pore area, and particle group-blocked area that were insufficiently wetted under the previous forward flow conditions. The enhanced mechanical disturbances alter the contact positions between particles, causing the re-released contaminants to enter the cleaning medium from the particle surface. The upstream and downstream contaminant concentrations and the particle surface contaminant release response are continuously collected during the reverse scouring process. When the downstream contaminant concentration falls back to the corresponding stage baseline fluctuation range after reaching its peak, and the particle surface contaminant release response simultaneously falls back to the corresponding stage baseline fluctuation range and remains stable for a preset time, the secondary migration-promoting treatment ends. If the termination condition is not met after the preset maximum duration of secondary migration-promoting treatment, the mechanical disturbance intensity is stopped from increasing and maintained below a certain value. The target mechanical disturbance intensity completes the current disturbance cycle, and the corresponding response state is marked as a secondary migration non-converged state, in order to avoid back scouring and excessive duration of enhanced mechanical disturbance.

[0045] In summary, the embodiments of this application have at least the following technical effects:

[0046] First, the initial distribution and particle size of contaminants in the waste plastic particles to be treated are obtained. The particles are then placed in a temperature-controlled cleaning medium, and the contaminant release conditions are sequentially changed using stepped temperature and intermittent mechanical disturbance. Next, the changes in contaminant concentration in the cleaning medium and the contaminant release response on the surface of the waste plastic particles are simultaneously collected at each disturbance stage. The continuous response is converted into a contaminant migration event sequence including the release start time, peak time, decay time, and re-release time. Then, based on the time interval between adjacent contaminant migration events and their corresponding temperature and mechanical disturbance states, the migration stages of contaminants from the internal retention zone of the particles to the surface release zone and then back to the cleaning medium are determined, and the contaminant migration path is reconstructed based on the continuity of each migration stage. Finally, based on the connection between the current migration stage and the next migration stage in the contaminant migration path, the corresponding immersion temperature, mechanical disturbance intensity, and cleaning medium flow direction are selected. This allows the waste plastic particles in the internal migration stage to continue to undergo migration-promoting treatment, while the waste plastic particles in the surface release stage enter the contaminant removal treatment. A secondary migration-promoting treatment is triggered when a re-release event is detected, resulting in plastic particles that have undergone path-based decontamination treatment. This application solves the technical problem that it is difficult to fully remove pollutants from the inside of waste plastic particles in the prior art, and that repeated washing leads to low treatment efficiency, thereby achieving the technical effect of improving the fullness of pollutant removal and the efficiency of cleaning treatment of waste plastic particles.

[0047] Example 2, based on the same inventive concept as the plastic resource recycling method in the foregoing examples, such as... Figure 3 As shown, this application provides a plastic resource recycling and processing system, wherein the system includes:

[0048] State Acquisition Module 11: Acquires the initial distribution and particle size of pollutants in the waste plastic particles to be treated, places the waste plastic particles in a temperature-controlled cleaning medium, and sequentially changes the pollutant release conditions with stepped temperature and intermittent mechanical disturbance; Event Sequence Construction Module 12: Synchronously collects the changes in pollutant concentration in the cleaning medium and the pollutant release response on the surface of the waste plastic particles to be treated during each disturbance stage, and converts the continuous response into a pollution migration event sequence including the release start time, peak time, decay time, and re-release time; Migration Path Reconstruction Module 13: Based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance conditions... The mechanical disturbance state determines the migration stages of pollutants from the internal retention area of ​​the particles to the surface release area and then to the cleaning medium, and reconstructs the pollutant migration path based on the continuity of each migration stage; the decontamination treatment module 14: according to the connection relationship between the current migration stage and the next migration stage in the pollutant migration path, selects the corresponding immersion temperature, mechanical disturbance intensity and cleaning medium flow direction, so that the waste plastic particles in the internal migration stage continue to undergo migration promotion treatment, so that the waste plastic particles in the surface release stage enter the pollutant removal treatment, and triggers a secondary migration promotion treatment when a re-release event is detected, so as to obtain plastic particles that have undergone path-based decontamination treatment.

[0049] Furthermore, the event sequence construction module 12 is used to execute the following method:

[0050] The changes in pollutant concentration in the cleaning medium and the release response of pollutants from the surface of the waste plastic particles to be treated are time-aligned to determine the change process of the two types of responses relative to the baseline of the corresponding disturbance stage. After the release response of pollutants from the surface of the waste plastic particles to be treated, which indicates the target pollutant leaving the particle surface, increases, it is detected whether the pollutant concentration in the cleaning medium changes in the same direction within a preset lag time. The changes in the release response of the waste plastic particles to be treated and the changes in the pollutant concentration in the cleaning medium that satisfy the sequential relationship are associated as a cross-interface migration event, and the time interval between the two is determined as the corresponding migration lag segment. After the cross-interface migration event ends, if the release response of the waste plastic particles to be treated increases again and the pollutant concentration in the cleaning medium changes again with a corresponding lag, the recurring response is associated as a subsequent cross-interface migration event. A pollution migration event sequence is formed according to the occurrence order of each cross-interface migration event and its migration lag segment.

[0051] Furthermore, the event sequence construction module 12 is used to execute the following method:

[0052] The release response of pollutants on the surface of the waste plastic particles to be treated and the rate and acceleration of change of pollutant concentration in the cleaning medium are calculated separately. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated increases from below a first release threshold to above the first release threshold, and the acceleration changes from negative to positive and continues for a first set time, the release start time is determined. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated reaches a local maximum and the acceleration changes from positive to negative, and the rate of change of pollutant concentration in the cleaning medium exceeds the medium response threshold within a preset lag time after the release start time, the time corresponding to the local maximum is determined as the peak time. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated is below a second release threshold and the acceleration remains less than zero or below a second acceleration threshold, and the rate of change of pollutant concentration in the cleaning medium is less than zero and continues for a preset decay duration, the decay time is determined. After the decay time, if the acceleration of the release response of pollutants on the surface of the waste plastic particles to be treated changes from negative to positive again and continues for a third set time, and the rate of change exceeds the first release threshold, and the pollutant concentration in the cleaning medium exceeds the medium response threshold again within a preset lag time, then the re-release time is determined.

[0053] Furthermore, the status acquisition module 11 is used to perform the following method:

[0054] The waste plastic particles to be treated are dispersed and spread so that they pass through the imaging detection area in a non-overlapping state. Multispectral images of the surface and contours of each particle are acquired. Based on the response differences between the characteristic bands of pollutants in the surface multispectral images and the bands of the clean plastic substrate, the pollutant coverage area on the surface of each particle is determined, and the equivalent particle size is determined based on the particle contour image. Using a single particle as a registration unit, the pollutant coverage area is mapped to the contour coordinates of the corresponding particle, forming an initial particle-level pollution distribution with pollutant coverage location, coverage area, and equivalent particle size. The spatial resolution of the pollutant coverage area is no greater than one-tenth of the equivalent particle size, so that subsequent pollutant migration events are correlated according to the initial particle-level location.

[0055] Furthermore, the event sequence construction module 12 is used to perform the following methods:

[0056] Waste plastic particles to be treated are grouped according to particle size range and loaded into multiple cleaning chambers with independent inlet and outlet liquid channels, forming particle clusters in each cleaning chamber. Pollutant concentration sensors are installed upstream and downstream of the particle clusters in each cleaning chamber, and surface pollutant release detection units facing the particle clusters are installed in the cleaning chambers. During each disturbance stage, the pollutant concentration of the cleaning medium upstream and downstream of each cleaning chamber and the pollutant release response of the surface of the waste plastic particles to be treated output by the release detection units are collected simultaneously. The change in pollutant released from the particle clusters into the cleaning medium is determined by the difference in pollutant concentration between the two sides of the cleaning medium, and the release start, peak value and decay process of the corresponding particle clusters are determined by the time change of the release response on the particle surface.

[0057] Furthermore, the status acquisition module 11 is used to perform the following method:

[0058] The stepped temperature includes multiple temperature steps that increase sequentially. The holding time of each temperature step is not less than the duration of the corresponding disturbance stage, and the heating rate between adjacent temperature steps does not exceed 5℃ / min.

[0059] Furthermore, the decontamination module 14 is used to perform the following method:

[0060] If no valid release response that meets the criteria is found in two consecutive migration stages, the corresponding temperature step is increased by a preset gradient and the duration of the current disturbance stage is extended.

[0061] Furthermore, the decontamination module 14 is used to perform the following method:

[0062] The cleaning medium flow direction is switched to reverse flushing, and the mechanical disturbance intensity is increased to 1.2 to 2 times that of the previous stage.

[0063] Example 3: Based on the same inventive concept as the plastic resource recycling method in the foregoing examples, this example provides a computer-readable storage medium for storing software programs, computer-executable programs, and modules, such as the program instructions / modules corresponding to the plastic resource recycling method in this application. The processor executes various functional applications and data processing of the computer device by running the software programs, instructions, and modules stored in the memory, thereby realizing the aforementioned plastic resource recycling method.

[0064] 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 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 recycling and processing plastics, characterized in that, The method includes: The initial distribution and particle size of pollutants in the waste plastic particles to be treated are obtained. The waste plastic particles to be treated are placed in a temperature-controlled cleaning medium, and the pollutant release conditions are changed sequentially by step temperature and intermittent mechanical disturbance. Simultaneously collect the changes in pollutant concentration in the cleaning medium and the release response of pollutants on the surface of the waste plastic particles to be treated at each disturbance stage, and convert the continuous response into a sequence of pollution migration events including the release start time, peak time, decay time and re-release time. Based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance states, the migration stages of pollutants from the internal retention area of ​​particles to the surface release area and then to the cleaning medium are determined, and the pollutant migration path is reconstructed based on the continuity of each migration stage. Based on the connection between the current migration stage and the next migration stage in the pollutant migration path, the corresponding immersion temperature, mechanical disturbance intensity and cleaning medium flow direction are selected to allow waste plastic particles in the internal migration stage to continue to undergo migration-promoting treatment, and waste plastic particles in the surface release stage to enter the pollutant removal treatment. When a re-release event is detected, a secondary migration-promoting treatment is triggered to obtain plastic particles that have undergone path-based decontamination treatment.

2. The plastic resource recycling method as described in claim 1, characterized in that, The continuous response is converted into a sequence of contamination migration events, including the release start time, peak time, decay time, and re-release time, including: Time alignment was performed on the synchronously collected data of changes in pollutant concentration in the cleaning medium and the response of pollutant release from the surface of waste plastic particles to be treated, and the change process of the two types of responses relative to the baseline of the corresponding disturbance stage was determined. After the release response of pollutants on the surface of the waste plastic particles to be treated, which indicates that the target pollutant leaves the particle surface, increases, it is detected whether the concentration of pollutants in the cleaning medium changes in the same direction within a preset lag time. The release response change of the waste plastic particles to be treated that satisfies the sequential relationship is associated with the change of pollutant concentration in the cleaning medium as a cross-interface migration event, and the time interval between the two is determined as the corresponding migration lag segment. After the cross-interface migration event ends, if the surface release response of the waste plastic particles to be treated shows an increase again and the concentration of pollutants in the cleaning medium shows a corresponding hysteresis change again, the recurring response will be associated as a subsequent cross-interface migration event, and a pollution migration event sequence will be formed according to the order of occurrence of each cross-interface migration event and its migration hysteresis segment.

3. The plastic resource recycling method as described in claim 2, characterized in that, The change in the surface release response of the waste plastic particles to be treated, which satisfies the aforementioned sequential relationship, is correlated with the change in the concentration of contaminants in the cleaning medium as a single cross-interface migration event, including: Calculate the release response of pollutants from the surface of the waste plastic particles to be treated and the rate and acceleration of change of pollutant concentration in the cleaning medium, respectively. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated increases from below the first release threshold to above the first release threshold, and the acceleration of change changes from negative to positive and continues for a first set time, the release start time is determined. When the rate of change of the release response of pollutants on the surface of the waste plastic particles to be treated reaches a local maximum and the acceleration of change changes from positive to negative, and at the same time the rate of change of the concentration of pollutants in the cleaning medium exceeds the medium response threshold within a preset lag time after the release start time, the time corresponding to the local maximum is determined as the peak time. When the rate of change of pollutant release response on the surface of the waste plastic particles to be treated is lower than the second release threshold and the change acceleration is continuously less than zero or lower than the second acceleration threshold, and the rate of change of pollutant concentration in the cleaning medium is less than zero and continues for a preset decay duration, the decay time is determined. After the decay time, if the acceleration of the change in the release response of pollutants on the surface of the waste plastic particles to be treated changes from negative to positive again and continues for a third set time, and the rate of change exceeds the first release threshold, and at the same time the concentration of pollutants in the cleaning medium exceeds the medium response threshold again within a preset lag time, then the release time is determined again.

4. The plastic resource recycling method as described in claim 1, characterized in that, Obtain the initial distribution and particle size distribution of pollutants in the waste plastic particles to be treated, including: The waste plastic particles to be processed are dispersed and spread so that the particles pass through the imaging detection area in a non-overlapping state; Collect surface multispectral images and particle contour images of each particle. Based on the response differences between the characteristic bands of pollutants and the bands of the clean plastic substrate in the surface multispectral images, determine the pollutant coverage area on the surface of each particle, and determine the equivalent particle size of the corresponding particle based on the particle contour images. Using a single particle as a registration unit, the pollutant coverage area is mapped to the contour coordinates of the corresponding particle, forming an initial pollution distribution at the particle level with pollutant coverage location, coverage area, and equivalent particle size. The spatial resolution of the pollutant-covered area is no greater than one-tenth of the equivalent particle size, so that subsequent pollutant migration events can be correlated according to the initial position at the particle level.

5. The method for recycling and processing plastics as described in claim 1, characterized in that, Simultaneously collect data on changes in contaminant concentration in the cleaning medium and the release response of contaminants from the surface of the waste plastic particles to be treated at each disturbance stage, including: The waste plastic particles to be treated are grouped according to particle size range and loaded into multiple cleaning chambers with independent inlet and outlet liquid channels. Particle clusters are formed in each cleaning chamber. Pollutant concentration sensors are installed upstream and downstream of the particle clusters in each cleaning chamber. At the same time, a surface pollutant release detection unit facing the particle clusters is installed in the cleaning chamber. During each disturbance stage, the pollutant concentrations of the upstream and downstream cleaning media in each cleaning chamber and the pollutant release response of the surface of the waste plastic particles to be treated, output by the release detection unit, are collected simultaneously. The change in pollutant released from the particle group into the cleaning medium is determined by the difference in pollutant concentrations of the cleaning media on both sides, and the release initiation, peak value and decay process of the corresponding particle group are determined by the time change of the release response on the particle surface.

6. The plastic resource recycling method as described in claim 1, characterized in that, The stepped temperature includes multiple temperature steps that increase sequentially. The holding time of each temperature step is not less than the duration of the corresponding disturbance stage, and the heating rate between adjacent temperature steps does not exceed 5℃ / min.

7. The plastic resource recycling method as described in claim 1, characterized in that, After selecting the wetting temperature, mechanical disturbance intensity, and cleaning medium flow direction according to the pollutant migration path, the method further includes: when no effective release response meeting the criteria appears in two consecutive migration stages, the corresponding temperature step is increased by a preset gradient and the duration of the current disturbance stage is extended.

8. The method for recycling and processing plastics as described in claim 1, characterized in that, The secondary migration-promoting process triggered when the re-release event is detected includes: switching the flow direction of the cleaning medium to reverse flushing and increasing the intensity of mechanical disturbance to 1.2 to 2 times that of the previous stage.

9. A plastic resource recycling and processing system, characterized in that, The system for implementing the plastic resource recycling method according to any one of claims 1-8, the system comprising: Status acquisition module: acquires the initial distribution and particle size of pollutants in the waste plastic particles to be treated, places the waste plastic particles to be treated in a temperature-controlled cleaning medium, and changes the pollutant release conditions in sequence with step temperature and intermittent mechanical disturbance. Event sequence construction module: Synchronously collect the changes in pollutant concentration in the cleaning medium and the release response of pollutants on the surface of the waste plastic particles to be treated during each disturbance stage, and convert the continuous response into a pollution migration event sequence including the release start time, peak time, decay time and re-release time; Migration path reconstruction module: Based on the time interval between adjacent pollution migration events and their corresponding temperature and mechanical disturbance states, determine the migration stages of pollutants from the internal retention area of ​​particles to the surface release area and then to the cleaning medium, and reconstruct the pollutant migration path according to the continuity of each migration stage. Decontamination treatment module: Based on the connection between the current migration stage and the next migration stage in the pollutant migration path, the corresponding immersion temperature, mechanical disturbance intensity and cleaning medium flow direction are selected to continue the migration-promoting treatment of waste plastic particles in the internal migration stage, and to allow waste plastic particles in the surface release stage to enter the pollutant removal treatment. When a re-release event is detected, a secondary migration-promoting treatment is triggered to obtain plastic particles that have undergone path-based decontamination treatment.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the plastic resource recycling method as described in any one of claims 1-8.

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