Vorrichtung und Verfahren zur Verwertung von Abfallpolymeren

摘要

Waste products consisting almost exclusively of PVC contain what are now regarded as environmentally unacceptable auxiliary materials and so must be converted to remove completely these toxic auxiliary materials. One method that can be used for disposal and conversion of even small volumes is degradative extrusion between 250 and 400 DEG C. At these temperatures the chlorine is more or less rapidly split off and can be recovered as HCL and reused in producing new monomers. PVC or plastic waste products containing PVC are freed of hydrochloric acid by thermal separation under 350 DEG C. The residual plastic is then preferably liquefied in an extruder, using largely halogen-free thermoplastic admixtures and the auxiliary materials used in the known degradative extrusion process, and these liquids are then burned with air or oxygen in a combustion chamber. Alternatively, the waste products consisting solely of PVC are freed of hydrochloric acid and then the temperature is raised high enough that the PVC is broken down. The resulting product is burned with air or oxygen or the resulting pyrolysis coke is used for metallurgical purposes. For this process variant, preferably a synchronous twin-screw extruder is used. These methods can also be used in other degradative processes for recycling plastics and are especially recommended for facilities that process large volumes.