Carbon emission model and evaluation analysis of vehicle waste tire different recycling processes based on reducing environmental pollution

To scientifically assess and quantitatively evaluate the carbon emissions associated with different treatment methods and processes for end-of-life vehicle tires, the carbon emission factor method was employed. Carbon emission models and carbon emission-reduction inventories were developed for the tire production, transportation, use, and recycling stages. Specifically, models and inventories were constructed for four treatment methods: Tire retreading, reclaimed rubber production, reclaimed rubber powder production, and pyrolysis, encompassing eight distinct processes: Hot retreading, cold retreading, atmospheric continuous desulfurization, screw extrusion, ambient grinding, cryogenic grinding, atmospheric pyrolysis, and vacuum pyrolysis. The carbon emissions, carbon reduction, net carbon surplus, and carbon reduction rate for each treatment method and process were calculated. Furthermore, sensitivity and economic analyses were conducted on the material mass and energy consumption in the production stage, which impact the total carbon emissions. The results indicate that among the four recycling methods, tire retreading production demonstrates the highest carbon reduction efficiency, followed by reclaimed rubber and reclaimed rubber powder production, while pyrolysis shows the lowest efficiency. Among the eight processes, cold retreading exhibits the most significant carbon reduction effect, with a carbon reduction rate of 59.30%. The ranking of carbon reduction efficiency is as follows: Cold Retreading > Hot Retreading > Ambient Grinding > Atmospheric Continuous Desulfurization > Screw Extrusion >Atmospheric Pyrolysis > Vacuum Pyrolysis > Cryogenic Grinding. Sensitivity analysis reveals a positive correlation between the material mass and energy consumption required in the production stage and the total carbon emissions; however, the impact of material mass on total carbon emissions is significantly greater than that of energy consumption.