Life cycle assessment of recycling copper slags as cement replacement material in mine backfill

In mining activities, cemented paste backfills (CPB) are widely used to provide structural support to underground openings and prevent surface subsidence. However, the cement requirement in CPB entails a significant environmental footprint and incurs major costs. To reduce cement usage and enhance the environmental benefits, recycled copper slag is proposed as a cement replacement material in CPB for copper mines. A life cycle assessment on CPB mixtures of different replacement plans was conducted based on publicly available data to evaluate the specific environmental impact, followed by a contribution and a sensitivity analysis investigating the influence of different processes and parameters on the environmental indicators. The results showed that replacing cement with copper slag can significantly reduce the environmental burden of backfill due to the reduction in energy-intensive cement production. Tailings drying methods with paste thickener and electricity-based power system construction are recommended for the industry to achieve optimum environmental effects.