Sorting and Pre-treatment: First, waste plastics need to be sorted to remove impurities such as metal and paper. The sorted plastics then need to be washed to remove surface dirt and residue. Washing is usually done with water or with the addition of a cleaning agent. The washed plastics then need to be dried.
Crushing and Grinding: The washed and dried plastics are crushed using a crusher or grinder to cut them into small pieces or powder for subsequent melting. During crushing, particle size must be carefully controlled, typically 3-5mm.
Melting and Filtration: The crushed plastics enter melting equipment (such as an extruder or internal mixer) and are melted into a liquid state at high temperatures. The melting temperature varies depending on the type of plastic, typically between 160-300℃. Stabilizers and plasticizers are added during the melting process to improve plastic properties. The molten plastics then need to be filtered to remove impurities and ensure particle purity.
Granulation: The filtered molten plastics are granulated using a granulator. Granulation methods mainly include water-cooled pelletizing and air-cooled pelletizing. Water-cooled pelletizing is suitable for high-temperature plastics, with a pellet diameter typically of 2-4 mm; air-cooled pelletizing is suitable for low-temperature plastics, with a pellet diameter typically of 1-3 mm. The pellets after pelleting require cooling and drying.
Packaging and Storage: The dried pellets are packaged using a packaging machine, typically in 25 kg bags or ton bags. Packaged pellets must be stored in a dry, well-ventilated environment, avoiding moisture and contamination.
