Enhanced Rock Weathering in Acid Mine Drainage: Carbon Removal Potential and Co-benefits

Abstract Enhanced rock weathering (ERW) involving the spreading of basaltic rock powder on cropland is gaining interest as a promising carbon dioxide removal (CDR) technique. To optimise CDR efficiency and address the limitations of mineral dissolution associated with cropland, this study explored the potential of deploying basalt-based ERW in acid mine drainage (AMD), utilizing its strong acidity and flow-through nature. One-dimensional reactive transport modeling was undertaken by simulating various AMD scenarios with pH levels of 2–4 and flow rates of 0.005–0.5 m³ s–1, with a range of particle sizes. Results indicate that a single AMD system could dissolve up to 10,500 tonnes (t) of basalt annually, potentially removing 3,660 t CO₂. AMD ERW may thus contribute to CDR with a co-benefit of arsenic removal. In the absence of direct basalt-based ERW applications to AMD settings, this study provides guidance for designing alternative ERW protocols alongside traditional cropland-ERW applications.