A life cycle assessment and comparative evaluation of global primary rare earth oxide supply chains

The rapid diversification of global rare earth production has increased supply-chain complexity and heightened concerns about environmental impacts, yet existing assessments remain fragmented and region-specific. This study provides a cradle-to-gate life cycle assessment (LCA) of rare earth oxide (REO) production across 14 representative supply chains, covering 12 mines in 9 countries. Using site-specific life cycle inventory data compiled from peer-reviewed literature and publicly available disclosures, we quantify environmental burdens per 1 kg REO with the TRACI midpoint method across ten impact categories. Results reveal clear contrasts between heavy and light rare earth pathways. Heavy rare earth oxide (HREO) chains exhibit systematically higher impacts, with in-situ leaching contributing 72 %–83 % of total burdens. Light rare earth pathways are dominated by mining, beneficiation and separation, which together account for 41 %–86 % of impacts. Chemical reagents are the primary hotspot across most categories, while electricity and diesel use strongly influence global warming potential and resource depletion. Differences in ore grade and technological maturity explain major inter-pathway variation, with high-grade deposits and advanced refining routes (e.g., Mount Weld, R8) showing substantially lower impacts. Transport contributes only 0.04 %–3.05 % overall, but becomes non-negligible for trucking-intensive, long-distance routes. By constructing the first globally harmonized, supply-chain-level LCA dataset for primary REOs, this study identifies key leverage points-reagent management, process upgrading, energy decarbonization and logistics optimization-to reduce environmental burdens and support more sustainable governance of critical mineral supply chains.