S2: Water Rock Interaction (Special Session)

[S2-09] Formation of magnesium carbonate minerals under high pressure CO₂ conditions

*Yuto Nishiki^1,2, Masao Sorai², Tsutomu Sato¹ (1. Eng., Hokkaido Univ., 2. AIST)

Keywords:Geological CO2 storage, Hydromagnesite, Magnesite, Nesquehonite, Supercritical CO2

Mg-hydroxide powder (3 g) and ultrapure water (30 mL) were set in a stainless reaction vessel (50 mL) placed in an oven (40, 60, and 80℃) and pressurized up to 10 MPa using supercritical CO₂. All Mg-hydroxide powder was dissolved, and Mg-carbonates were precipitated under all the conditions. The precipitates were identified as nesquehonite at 40℃, nesquehonite and magnesite at 60℃, and hydromagnesite and magnesite at 80℃. In addition to temperature, other parameters (e.g., CO₂ pressure) are possibly determinants for mineral species of Mg-carbonate precipitates.