Process description
To recycle used PET bottles demands some steps that you can not avoid. Here we explain all sections and comment how we have chosen to solve some problems.
Size reduction
The PET bottles fed to the plant are chopped to a particle size of 8 – 12 mm . The particle size of the flakes is determined by using different sizes of screens that keep the plastics inside the cutting chamber until they have reached their target size.
Since the chopper is the machine where all the input dirt is coming, it is also the machine where the main wear of the plant will be found. The more dirt you put into the plant, the higher will the wear be. Some foreign objects like pieces of metal may cause breakdown of the chopper. By removing as much as possible of foreign objects, before feeding the bottles to the plant, you will reduce wear and downtime of the plant.
By adding water to the chopper we achieve less wear on the machine, due to that sand and dirt is flushed through the outlet screen instead of being chopped together with the bottles.
Washing
When the bottles have been chopped we use a specially designed friction washer where the flakes are treated in an intensive rubbing process.
The water tank is provided with heating elements that enables washing with warm water, that soften the plastic surface and simplifies the removal of contamination. It is also possible to add detergent (e.g. NaOH) to increase the washing effect.
Separation of paper labels
During chopping the paper labels will be dissolved into pulp, which is removed by using our high speed centrifuge and hydro cyclone. In the centrifuge the flakes are separated from the water and contamination, which is removed via a sludge outlet.
Separation of caps, rings and PP labels
Due to the difference in their density we are able to separate the light PE and PP from the heavier PET by using gravity separation.
Rinsing
During the different process stages, the flakes are in contact with dirt, washing detergents and other foreign objects. In the last process we rinse the flakes with clean water to flush off residuals of detergent and any remaining contamination.
Air transport drying
In the final stage a hot air transport is used for drying and transporting the final product to the outlet. This is performed with a pipe dryer where the residual surface moisture is evaporated due to the high temperature of the transporting air. The water is picked up by the air and leaves through an exhaust outlet.
Control system
The delivered mini-plant is completely wired and after you plug in the main three-phase conductors your equipment is ready. The machine is PLC controlled and all units are interlocked. Start and stop of the plant is performed by pushing one button on screen.
If any error occurs a text messages will be presented on a display screen. If you encounter problems you can not find, we have the ability to connect via modem directly to your machine and troubleshoot online.
