LCA-based environmental benefit allocation between steel and cement industries in steel byproduct recycling

Among the steel byproducts, more than 80% of blast furnace slag is recycled in the cement industry. However, the criteria for allocating environmental benefits between the steel and cement industries need to be more transparent. This study aims to allocate the environmental benefits between the steel and cement industries when granulated blast furnace slag (GBFS) is recycled to replace Portland cement in the production of slag cement (SC). Specifically, this research proposes how the recycling of GBFS, a byproduct of the steel production process, can quantify environmental burdens and benefits from both attributional life cycle assessment (ALCA) and consequential life cycle assessment (CLCA) perspectives. It also suggests methods for allocating these environmental benefits between the steel and cement industries. Following the final agreement on the EU Carbon Border Adjustment Mechanism (CBAM), this study emphasizes the growing importance of interconnected allocation of environmental benefits through recycling. Various allocation methods using ALCA and CLCA approaches have been assessed, significantly impacting the analysis results. Furthermore, these findings of the study are expected to provide guidance for potential policy decisions and internal decision-making processes, highlighting the environmental benefits that GBFS recycling offers to both steel and cement industries.