Toward Decarbonized Metal Mining and Shifting Environmental Impacts: A Quantitative Comparative Assessment

Area of Science:

• Environmental Science
• Materials Science
• Sustainable Engineering

Background:

• The global demand for metals like copper, cobalt, gold, and rare-earth elements is rapidly increasing due to societal electrification.
• Conventional mining practices contribute significantly to greenhouse gas emissions and generate vast amounts of solid waste (tailings and overburden).

Purpose of the Study:

• To conduct a comparative life cycle assessment of two decarbonized mining routes: fully electrified conventional mining and electrokinetic in-situ recovery (EK-ISR).
• To evaluate the environmental impact, focusing on greenhouse gas emissions and solid waste generation, for the extraction of key metals.

Main Methods:

• Comparative life cycle assessment (LCA) was employed to analyze the environmental footprint of different mining techniques.
• The study focused on the extraction of copper, cobalt, gold, and rare-earth elements under two scenarios: electrified conventional mining and EK-ISR.

Main Results:

• Electrifying conventional mining can decrease carbon emissions by over tenfold but does not solve the issue of solid waste production.
• Electrokinetic in-situ recovery (EK-ISR) offers a transformative solution by eliminating the need for waste storage, potentially avoiding over 100 Gt of waste for copper extraction alone in 30 years.
• While EK-ISR's energy intensity may match conventional mining, its primary environmental benefit lies in waste reduction.

Conclusions:

• The future of sustainable mining involves transitioning environmental burdens from permanent waste storage to temporary land use for renewable energy infrastructure.
• EK-ISR presents a viable pathway for significantly reducing the environmental impact of metal extraction, particularly concerning waste generation.