Towards greener metal production: A life cycle assessment model for copper-gold-silver mining and mineral processing operations

Abstract

Copper, gold, and silver (CGS) are indispensable non-ferrous metals, widely recognized for their critical roles in various industrial and technological applications. However, the environmental repercussions linked to combined CGS production have been insufficiently explored. This research investigates the ecological impacts of integrated CGS production in the context of developing countries, with Pakistan as a representative case. The environmental impacts of CGS production were assessed using the Life Cycle Assessment (LCA) framework implemented in SimaPro 9.0. Data from the Ecoinvent v3 database supported the analysis, with midpoint and endpoint results, including uncertainty evaluation, derived through the ReCiPe 2016 Midpoint (H) and Endpoint methodologies. The results identified water consumption during processing as the most substantial environmental impact. Group contribution analysis indicated that material consumption heavily affects land use and freshwater eutrophication, while energy consumption notably impacts fossil resource scarcity, ozone depletion, acidification, ecotoxicity, and particulate matter formation. Comparative analysis of co-products revealed that gold concentrate had the greatest impacts, particularly in freshwater and marine ecotoxicity, as well as human toxicity, largely due to tailings and electricity use. Key substances contributing to the environmental burden included diesel, coal, crude oil, heavy fuel oil, electricity, flotation agents, and magnesia chrome bricks. Endpoint damage assessment showed that producing one tonne of bulk concentrate led to 2.15E-02 DALYs of human health damage, 1.27E-04 species. yr of ecosystem damage, and $657.88 in resource depletion. Transitioning from coal to renewable energy significantly reduced environmental impacts across all categories. Technical measures are also recommended to support greener and more sustainable CGS production. The findings of this research are crucial for policymakers and industry stakeholders in Pakistan, as well as for regions facing the challenge of balancing industrial growth with environmental sustainability.