Zinc regarding the utilization of waste tires by pyrolysis

Abstract

The major goal of our study was to demonstrate how to eliminate zinc from the products of waste tire pyrolysis and avoid its environmental circulation. The new tire utilization manner consists of a separate combustion of the pyrolytic char containing 5.1 wt. % zinc and a collection of such obtained ash (10.4% yield) that contains 42 wt. % of zinc. The ash is a good candidate for metallurgical recovery of metallic zinc. The study demonstrates that pyrolytic char, because of its very low BET surface area of 43-60 m2/g, should not be transformed into activated carbon. High surface areas reported in literature (800-910 m2/g) for some pyrolytic chars were achieved after a complex and expensive activation process. Moreover, the study proved that zinc derivatives in tire-driven pyrolytic chars could be released to the environment since they were partly leached in H2O and etched in 0.1 M HCl solution. The study demonstrates that zinc can be eliminated from environmental circulation during tire pyrolysis and proposed an alternative solution to the transformation of pyrolytic char into activated carbon.