Post-consumer recycling requires several processing steps such as sorting (material separation), size reduction, washing, drying and pelletizing in order to achieve good quality recycled pellets as the end product.
Good degassing and filtration are probably the most important processes in pelletizing machines when it comes to post-consumer recycling. In many occasions, a two-stage recycling pelletizing machine is preferred by professional recyclers who focus on post-consumer recycling.
The washed material is fed into the compactor for a quick densifying process (which at the same time further dries the material by natural heat and friction); this helps to stabilize the material feeding into the extruder. The material then goes into the first (main) extruder for the filtration process and a two-vented degassing (installed with high efficiency vacuum system). The material then passes through an open area for the third and final degassing, and enters the second stage (short) extruder where the second filtering process is done.
The two-stage pelletizing line significantly improves the quality of the recycled pellets as the washed material goes through two filtration and three degassing steps in both extruders combined. As a result, the final pelletizing process becomes more stable and easier to operate because the material is already well prepared and pre-conditioned.
A post-consumer recycler located in Belgorod, Russia who is dedicated in the recycling of municipal waste has a complete set up: The automatic sorting lines initially separate paper, glass, metal and plastic. The plastics are then separated by groups: PET bottles; films of HDPE and LDPE; and rigid plastic and followed by two washing lines - one for PET bottle and another for plastic films. After washing and drying the process is completed in the POLYSTAR pelletizing recycling machine. The recycled pellets are mainly used for producing plastic boxes for vegetables.
To date, in Russia 68 sets of Polystar plastic pelletizing machines have been installed since 2012. Of these machines, 45 lines are dedicated specially for post-consumer recycling.
Source：Plastics News Asia