Evaluation of the environmental impact of direct hot rolling, ECAP and FSE for aluminum chips recycling

With the increasing global demand for aluminum, the environmental challenges associated with primary aluminum production, such as high energy consumption and greenhouse gas emissions, need innovative recycling solutions. Recently, unconventional aluminum recycling methods, known as Solid-State Recycling (SSR), have been developed. These processes bypass the melting stage, resulting in significant energy savings and reduced material losses. This paper presents a Life Cycle Assessment (LCA) study of the newly developed Direct Hot Rolling (DHR) process for recycling aluminum chips, focusing on the environmental impacts of chips degreasing and comparing DHR with other SSR methods. The DHR process, an emerging solid-state recycling (SSR) technology, offers a promising alternative to conventional methods by reducing energy use and emissions. However, the introduction of a degreasing phase is necessary to possibly scale the process for industrial applications, adding new environmental considerations. Using the SimaPro software with a “gate to gate” approach, this study evaluates the environmental performance of DHR both with and without the degreasing phase, to understand the environmental impact of this step. Then, based on data available in literature, the direct rolling process is compared with ECAP and FSE techniques. The results show that the degreasing process significantly contributes to aquatic and terrestrial ecotoxicity due to the chemicals used, highlighting a trade-off between material quality and environmental liability. On the other hand, DHR has a lower overall environmental impact if compared to ECAP and FSE. Additionally, DHR demonstrates significantly lower material losses compared to ECAP and FSE, making it more resource efficient.