Precipitation of magnesite from water-scCO2 solutions is crucial to mineral trapping during geologic carbon sequestration. Experiments were performed using batch reactors at 100 degrees C and 100 bar PCO2 for 14 days. Forsterite and magnesite powders were used to study the effect of initial substrate on magnesite precipitation, and parallel experiments with synthetic magnesite were used to study its dissolution. Measurements of changes in the aqueous phase were combined with solid phase characterization with scanning electron microscopy and X-ray diffraction. The critical saturation index for magnesite at 100 degrees C and 100 bar PCO2 was 2. Precipitation was fastest when solutions were seeded with magnesite to remove nucleation as a rate-limiting step. Relative to mineral-free solutions, forsterite did not accelerate magnesite nucleation. The extent of magnesite dissolution increased with increasing salinity. However, neither precipitation nor dissolution of magnesite reached equilibrium within 14 days of reaction.

Precipitation of magnesite in the water-scCO<sub>2</sub> system: Effects of supersaturation, mineral substrate, and salinity

245th National Meeting (2013)

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Precipitation of magnesite in the water-scCO2 system: Effects of supersaturation, mineral substrate, and salinity

Precipitation of magnesite in the water-scCO₂ system: Effects of supersaturation, mineral substrate, and salinity