Comparative life cycle assessment of recycling nickel slag in various production industries

Nickel is an important element for the development of telecommunication, energy storage, and electric vehicles. However, large amounts of nickel slag are generated during the smelting process, posing threats to ecosystem and human health if landfilled, so the selection of appropriate nickel slag recycling technologies is vital to the environment. In this study, we evaluate nickel slag as potential input material for geopolymer pipes, asphalt, concrete, and mine backfill production in Australia. A cradle-to-gate life cycle assessment (LCA) is conducted to investigate the environmental impacts of those products embedding nickel slag, and the relevant influence compared to nickel slag landfilling. The results indicate that incorporating nickel slag in geopolymer pipes and mine backfill is more beneficial to the products’ sustainability. Notably, compared to the landfilling scenario, all the recycling applications are encouraged to be applied in practice. • First comparative LCA of nickel slag recycling pathways in Australia • All recycling options outperform landfilling in most impact categories • Mine backfill with modified nickel slag identified as the optimal application • Using slag in concrete/asphalt increases environmental footprints