Shiimi et al. (2026): A field trial demonstrating CO₂ removal through enhanced weathering in mine tailings: design, commissioning and early performance of a European Union-funded pilot
Rosalia Shiimi, Will Savage, Evangelos Mouchos, Ottomar Brussee, Erik Ronne, Steven Pearce, IN: ResearchGate (preprint)
Tailings from mafic and ultramafic mines can be utilised to neutralise acids, and capture and store carbon dioxide (CO₂) via enhanced rock weathering (ERW). As part of the European Union (EU)-funded C-SINK project, Boliden’s active Kevitsa Mine, Finland, hosts a field trial to develop scalable monitoring, reporting and verification (MRV) for carbon dioxide removal (CDR). At Kevitsa, a 2 m deep, 25 m² filtered tailings test cell was installed in August 2025 to quantify ERW-driven CDR and establish a mine-ready MRV approach. Filled with filtered tailings, the cell is equipped with 3 vertical stations, with ports at various depths. Each port includes CO₂ and oxygen (O₂) sensors plus temperature, water content and electrical conductivity (EC) probes, for continuous, depth-controlled pore/void monitoring. A pH probe tracks near-surface changes. To capture reaction products and quantify carbon flux, a drainage well with an autosampler collects leachate for laboratory analysis of pH, EC, alkalinity, dissolved inorganic carbon, major cations/anions and trace elements. Determination of CDR is carried out using these sensor and leachate chemistry data, coupled with periodic solid-phase sampling of tailings for in situ carbonate formation evidence.