Promoting sustainable mining: A life cycle assessment model for small-scale underground chromite mining and processing operations

Chromite ore is crucial for industries such as metallurgy, chemicals, and refractories, yet its environmental impacts, stemming from small-scale mining operations, remain underexplored. This study assesses the environmental impacts of chromite production and processing in small-scale mining operations, focusing on Pakistan as a representative case in developing countries. Life Cycle Assessment (LCA) was performed using SimaPro 9.0 software, with background data from the Ecoinvent v3 database and midpoint results calculated using the ReCiPe 2016 Midpoint and Endpoint (H) method, including uncertainty analysis. The standardized results show that marine ecotoxicity and human carcinogenic toxicity are the most harmful categories, with gangue and waste handling, underground mining, and processing operations as the main contributors. Group contribution analysis indicates that material consumption has a significant environmental impact in the human non-carcinogenic toxicity, terrestrial ecotoxicity, and land use categories. Energy consumption primarily impacts stratospheric ozone depletion, ionizing radiation, water consumption, marine eutrophication, terrestrial acidification, freshwater eutrophication, and fine particulate matter formation, while transportation activities contribute most to ozone formation-terrestrial ecosystems, global warming, and fossil resource scarcity. Substance contribution analysis identified transport, steel, electricity, and diesel consumption as the main environmental contributors. The endpoint damage assessment showed that producing one tonne of chromite ore results in 4.30E-03 DALYs in human health impact, 2.29E-06 species.yr in ecosystem damage, and $19.07 in resource depletion. Sensitivity analysis showed that a 5 % reduction in material inputs improves global warming in transportation and reduces freshwater and marine ecotoxicity, and human carcinogenic toxicity in ore processing and gangue handling by 5 %. Switching from coal to renewable energy significantly reduced environmental impacts across all categories. Finally, this study recommends strategies to improve sustainability and environmental performance in small-scale chromite ore production.