Improving the Quality of Tyre Char as Part of a Closed-Loop Economy

The escalating accumulation of waste tyres necessitates the formulation of robust and economically sustainable waste management strategies. In response to this pressing concern, pyrolysis has emerged as a pivotal technology for tyre recycling, affording valuable by-products including charcoal, pyrolysis oil, and pyrolysis gas, contingent upon specific process parameters. Of particular significance is the valorisation of the solid fraction resulting from tyre pyrolysis, which holds promise for the reintroduction of this raw material into various production processes. This study explores three distinct processes aimed at enhancing the quality of carbonaceous materials: (1) heat treatment, which results in the remarkable reduction of volatile fractions by up to 94 %; (2) zinc leaching using a 20 % NaOH solution, achieving 59 % zinc extraction for potential electrochemical recovery; and (3) sulphur binding through CaCO₃ washing, effectively capturing 95 % of the sulphur content and mitigating SO_x emissions. The paper comprehensively outlines the advantages and limitations of these proposed solutions, while providing an in-depth evaluation of potential applications for charcoal based on the specific treatment methods used. The findings presented herein make a substantial contribution to the advancement of sustainable techniques for the valorisation of waste tyres, thereby bolstering environmental conservation efforts and fostering resource efficiency within industrial applications.