Synergistic benefits of recovered carbon black demineralisation for tyre recycling

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.