Dunite carbonation in batch-tubular reactor

For geological carbon sequestration, the reaction of aqueous CO₂ with silicate rock permits carbonate formation, achieving permanent carbon sequestration. The fractures available in silicate rock provide significant surface area for the precipitation of carbonates. The experiments were performed in a batch tubular reactor under diffusion-limited condition, with a special arrangement of a narrow tube filled with a 2800 g/L dunite slurry. The tube was kept open from the top, standing vertically filled with a CO₂-rich bulk solution under 1 barg CO₂ and temperatures ranging from 25 to 75 ^oC for 7-30 days. After 7 days of the experiment, magnesite precipitation was seen inside the tube and the precipitation was continued for up to 30 days. The magnesite precipitation was identified by micro-Raman spectroscopy, X-ray diffraction, and scanning electron microscopy. Additionally, SiO₂ formation was seen in relative close vicinity to the magnesite precipitation. The precipitation on the surface of silicate rock might cover the fractures and pore spaces available, which may over time reduce the dissolution rate of dunite. Graphical Abstract.