Evaluating the Environmental Sustainability of Silica Passivation for Acid Mine Drainage Treatment in Moatize's Coal Industry

Acid mine drainage (AMD) is a significant environmental concern associated with coal mining. This study investigates the environmental impact of silica passivation as a method for AMD prevention. Life cycle assessment (LCA) identified a low impact on soil acidity but a substantial concern regarding climate change due to silica transportation, processing, and energy use. Scaling the findings to a large-scale mine highlights the potential for significant environmental damage from acid rain, greenhouse gas emissions, and ecotoxicity. The paper proposes strategies to improve the environmental sustainability of silica passivation, including sourcing local or recycled silica, utilizing renewable energy, developing bio-based processing chemicals, and implementing long-term monitoring. By focusing on cleaner materials, processes, and energy sources, silica passivation can become a more sustainable solution for preventing AMD. The evaluation method can be applied to other passivation alternatives to compare and identify the most environmentally friendly approach for mine operations.