Toward Site-Specific Life-Cycle Assessment for Mining Activities: Methodological Framework and Application to 35 Production Sites in Canada.

Metals are essential to a wide range of strategic sectors, and their demand is expected to increase rapidly, along with associated environmental impacts. Yet, the ability of life-cycle assessment (LCA) to guide sustainable decisions remains constrained by life-cycle inventory (LCI) data that are incomplete and insufficiently representative across time, technology, and geography, often failing to capture site-level specificity. Building on MetalliCan, a high-resolution data set of Canadian mining and metallurgical activities, this study proposes a modular framework to construct site-specific and production-weighted inventories for mining products. The framework integrates facility-level environmental data and applies a hierarchical data-driven strategy that prioritizes site-specific parametrization, complemented by archetype-based inference and literature-derived proxies. Site-specific inventories are further integrated with regionalized background supply chains and spatially explicit environmental flows. Using this approach, 35 site-specific inventories are constructed for gold-silver, copper, nickel, uranium, molybdenum, and zinc mining and implemented in Brightway2. Life-cycle impact assessment is performed using the IMPACT World+ 2.1 method. Results reveal pronounced site-level heterogeneity, with potential impacts varying by up to a factor of 13 across facilities producing the same product and by up to a factor of 6 relative to background proxy data sets, indicating that reliance on generic inventories can mask critical differences. Overall, this work highlights the importance of granular inventories for robust environmental assessment and science-based policies.