An estimation of the amount of dissipated alloy elements in special steel from automobile recycling

According to the concept of a circular economy, further promotion of reuse and recycling might aid in closing the loop. However, material recycling may cause various types of material losses due to thermodynamic limitations and product complexity. In this study, we focused on automobile engines and their reuse, with the aim of quantifying the amount of dissipated steel alloy and its constituent elements (nickel and chromium) from the engine recycling process. We also elaborated upon their dissipation paths by using the MaTrace model [S. Nakamura, et al., MaTrace: Tracing the fate of materials over time and across products in open-loop recycling, Environ. Sci. Technol. 48, 7207 (2014)]. We evaluated the impact mitigation of material dissipation and the effects of reuse on the extension of product service life. We found that 22% of steel, 21% of nickel, and 63% of chromium was dissipated in total after 50 years; typically, nickel dissipates during the recovery process while chromium does so during the refinery process. Although the impacts on the reduction of material losses remained nearly the same after replacing 40 of 100% material recycling to parts reuse, greater possibilities could be achieved with respect to the service life extension of products when compared with 100% recycling.