Synergistic benefits of recovered carbon black demineralisation for tyre recycling

• Published in: Resources, conservation and recycling conservation and recycling, 2023-11, Vol.198, p.107124, Article 107124
• Main Authors: Bowles, Alex J, Wilson, Amy L, Fowler, Geoffrey D
• Format: Article
• Language: English
• Subjects: Demineralisation; Metal recycling; Pyrolysis; Recovered carbon black; Waste tyre; Zinc
• ISSN: 0921-3449; 1879-0658
• DOI: 10.1016/j.resconrec.2023.107124

•Waste tyre rubber derived metals have a high value ($103-257/tonne RCb).•RCb from batch, thermal pyrolysis was demineralised hydrothermally and with HCl.•Carbon content, homogeneity, surface chemistry, and structure improved.•Demineralisation allows for synergistic RCb improvement and metal recovery. Low levels of tyre recycling persist due to the lack of an appropriate technology. Pyrolysis is a suitable method to process waste tyres as it allows for the recovery of carbon-black components via the production of Recovered Carbon black (RCb). Although this product has potential applications as a recycled filler material, inorganic residues currently inhibit performance of RCb, hindering closed-loop tyre recycling. To address this, RCb was demineralised by hydrothermal washing and by using hydrochloric acid at two different concentrations (0.1 M, 5 M) to assess impacts on the physiochemical properties of the RCb. Ash content was reduced from 16.1% to between 5.8 and 13.1%, due to reductions in zinc, sulphur, iron, and aluminium content. This improved the physiochemical properties of the RCb significantly. Calculated estimates regarding the value of metals removed by RCb demineralisation (∼$155/tonne of RCb), elucidated the potential opportunity for metal recovery from waste tyre rubber. [Display omitted]