What Workers Need to Do During PET Bottle Recycling and Washing Process?
In the PET bottle recycling and washing line process, although many links have been automated, there are still some key links that need to be manually operated or assisted by humans to ensure the quality and production efficiency of the final PET bottle flakes. The following are the main tasks that must be completed by manual operation. For example: feeding (unpacking and feeding), sorting PET bottles (sorting colors and materials) and collecting PET flakes.
I. Manual Sorting of PET Bottles
Purpose: Remove impurities that do not meet the recycling requirements and improve the purity of PET recycled materials.
Reason: The current automatic sorting equipment (such as NIR near-infrared sorting machine, color sorting machine) still has a probability of misjudgment and requires manual assisted screening.
II. Manual Operation Content:
Remove non-PET materials:
1. PVC, PP, HDPE, PS and other plastic bottles.
2. PETG bottles (such as wine bottles), due to their low melting point, will cause PET recycled materials to become brittle.
3. Composite material bottles (containing high barrier layers such as EVOH and PA).
4. Eliminate special contaminated bottles: edible oil bottles, cosmetic bottles, chemical bottles, etc., to avoid residues from contaminating PET bottle flakes.
III. Classify PET bottles of different colors:
Transparent, blue, green, and brown PET bottles are generally recycled separately to maintain the color and purity of the final PET bottle flakes.
Importance: Manual sorting is the first line of defense to ensure the quality of PET bottle flakes. The cleaner the sorting, the higher the efficiency of the subsequent process and the better the quality of the final product.
VI. Manual intervention in the crushing process
Purpose: To ensure stable operation of the crusher and avoid jamming the machine due to special bottles or foreign objects.
Manual operation content:
Monitor the feed of the crusher to prevent oversized PET bottles (3L, 5L) or unremoved metal, glass, and hard plastic from entering the crusher, causing damage or blockage.
When encountering a blockage, it is necessary to manually pause the machine and clean up the stuck foreign objects. Regularly check the wear of the crushing blades and adjust or replace them if necessary.
Importance:
The crushing process is usually fully automatic, but due to the complex sources of recycled PET plastic bottles, manual monitoring can prevent accidental blockages and improve production continuity.
V. Manual monitoring of the cleaning stage
Purpose: To ensure that the water quality, temperature and reagent ratio of the alkaline washing, hot washing and rinsing processes meet the requirements.
Manual operation content:
Monitoring water quality and chemical concentration:
Parameters such as alkaline washing (NaOH solution concentration 1-2%) and hot washing (water temperature 80-90°C) need to be manually checked and adjusted according to the situation.
If there is too much foam or there are still adhesions on the surface of the bottle flakes during the cleaning process, the amount of detergent added needs to be manually adjusted.
Check floating objects and sediments:
When it is found that the bottle caps, labels, and impurities are not completely separated, manual intervention is required to adjust the process parameters or clean the impurities in the flotation tank.
Importance:
At present, the degree of automation of the PET bottle washing line is relatively high, but the water quality, temperature, and reagent concentration still need to be manually monitored to ensure that the cleanliness of the PET bottle flakes meets the requirements.
VI. Manual monitoring and sorting (gravity separation + optical sorting)
Purpose: To ensure that impurities such as HDPE/PP bottle caps and PVC labels are completely separated.
Manual operation content:
Observe whether there are PET bottle flakes sinking in the flotation tank (PET should float, HDPE/PP/PVC should sink to the bottom). If there is an abnormality, the sorting parameters need to be adjusted.
Monitor the accuracy of automatic sorting equipment such as color sorters and NIR (near infrared sorters). When PETG bottles and PET bottles with glue that cannot be separated by the color sorter are found, they need to be manually removed to avoid affecting the melting performance of PET bottle flakes.
Importance:
Automatic sorting equipment can improve efficiency, but it cannot completely replace manual labor, especially for the removal of special contaminated bottles and misjudged bottles.
VII. Manual inspection of the quality of the final PET bottle flakes
Purpose: To ensure that PET bottle flakes meet the requirements of recycled granulation, spinning or food-grade recycling.
Manual operation content:
Visually check whether the PET bottle flakes contain impurities (PVC, EVOH, metal particles, etc.).
Check whether the transparency and color of the bottle flakes meet the standards.
Take samples and send them to the laboratory for testing of IV value, ash content, residual impurity content and other indicators.
If unqualified bottle flakes are found, they need to be manually re-sorted to avoid affecting the quality of the entire batch.
Importance: The machine can sort most impurities, but the final quality still needs to be manually tested and confirmed to ensure that the PET bottle flakes can meet customer requirements.
VIII. Equipment maintenance and emergency treatment
Purpose: To ensure that the PET bottle recycling and washing line can operate normally and prevent downtime due to equipment failure. Manual operation content:
Regularly check and maintain equipment:
The wear of the crusher blade. After each crushing of a certain amount of PET bottles, the blade needs to be sharpened or replaced.
Whether the nozzle of the cleaning equipment is blocked and whether it needs to be cleaned or replaced.
Whether the optical sensors of the color sorter and NIR sorter are working properly.
Emergency treatment:
When the equipment is abnormal (such as blockage, overload, abnormal noise, etc.), stop the machine in time for processing.
Importance:
Equipment maintenance is the key to ensuring the stable operation of the production line, and manual inspection and emergency treatment are indispensable.