Utilisation of PVC waste and PVC char in steelmaking and other processes

Plastics belong to a large group of materials of natural or synthetic origin. The increasing production and demand of plastics also increases the pressure on finding a good solution for treating the vast amounts of plastic waste. Stress is, in particular, put on the development of processes which would be at the same time economical, efficient and environmentally friendly. Different approaches and new technologies have been applied in waste treatment plants of commercial size. Nonetheless, the design for a treatment of polyvinylchloride (PVC) plastic waste is special. About 5.5 Mt of PVC are produced yearly in the EU. As a result of its specific composition and properties, the waste treatment of PVC faces characteristic technical and ecological obstacles. PVC is produced in flexible or rigid formulations and its use is favoured in areas with high requirements for physical endurance. However, these properties are induced by introducing chlorine and additives that may contain heavy metals, which cause complicaions in the treatment of PVC waste and further utilisation of the residues of the PVC waste treatment. On the other hand, the calorific value of the char after waste treatment is high, about 35 MJ/kg, so it could be valuable as a fuel or reductant in industrial processes. However, nowadays is PVC waste mostly landfilled. The work described in this paper focuses on the treatment and utilisation of PVC waste and residues from thermal degradation of PVC. Samples of PVC waste were thermally degraded and their chemical and physical properties were determined. The chemical analysis showed that the content of some heavy metals and trace elements, such as lead or calcium, was enriched to a large extent in the char, which could cause difficulties in further utilisation of the char. Processes such as recycling, iron making or coke making application were examined as potential alternatives on the basis of the knowledge of the specific properties and composition of PVC waste and PVC chars.