Environmental assessment of noble metals recovery from e-waste: an ESCAPE and LCA-based comparative analysis towards design for sustainability

The search for environmentally safer methods for recovering precious metals from electronic waste, through "urban mining", is gaining increasing research interest. Supporting these efforts requires simplified yet robust tools for sustainability assessment to guide the development of emerging technologies. The ESCAPE approach (Evaluation of Sustainability of material substitution using CArbon footPrint by a simplifiEd approach) provides a simplified method for comparing recovered or substitute materials with primary ones, focusing on carbon footprint and embodied energy as key metrics. This study evaluates the ESCAPE approach alongside the Life Cycle Assessment (LCA) methodology, applying both to an innovative hydrometallurgical method for extracting copper, silver, and gold from waste Random Access Memories (RAMs), tested on a laboratory scale. Results were used to assess the consistency between ESCAPE and LCA in identifying key parameters affecting the environmental impact of the recovery method and enabled a preliminary comparison based on available data for primary noble metals extraction. A dual mass and economic allocation approach was used for the LCA, and a Monte Carlo uncertainty simulation was applied to evaluate the robustness of the results. The findings reveal that the ESCAPE approach effectively identifies a significant portion of the system's potential environmental impacts, closely aligning with LCA outcomes. However, discrepancies emerge in specific environmental impact categories and when considering an economic allocation method. The here proposed conceptual framework aims to support the early-stage development of innovative and environmentally safer recycling methods, guiding them towards more sustainable and efficient configurations.