Integrated life cycle assessment for quantifying the carbon impact of rare earth elements mining

The growing reliance on rare earth elements (REE) poses challenges to achieving a just, low-carbon transition. Intensified extraction from REE deposits increases carbon emissions and environmental stress, particularly in ecologically sensitive regions. Here, we present a comprehensive life cycle assessment (LCA) of carbon impacts from REE production in ion-adsorption deposits (IADs), expanding the scope of existing studies by integrating industrial stages (mining, transportation, smelting, and separation) with ecological terrestrial carbon storage loss (vegetation and soil). Vegetation carbon loss was estimated using the CASA model by comparing net primary productivity between mined and unmined areas, while soil carbon loss was calculated based on soil organic carbon (SOC) density and the extent of disturbed areas. Production-related emissions were calculated using IPCC emission factors and on-site measurements. Our results reveal a dual carbon impact: in the Renju REE deposit, mining caused a loss of 1599.6 t soil carbon and 3745.1 t vegetation carbon. Simultaneously, refining and separation were the most carbon-intensive stages, emitting 25.12 kg CO₂-eq/kg REO. Hydrochloric acid, oxalic acid, and magnesium oxide consumption were the largest contributors. The results highlight the need for mitigation strategies, including reducing land disturbance, reforestation, renewable energy adoption, and cleaner extraction technologies. This integrated diagnostic framework offers a transparent and robust approach for quantifying the full carbon footprint of REE production, providing essential data for aligning climate mitigation targets with ecological restoration planning in critical mineral supply chains.