CO 2 mineralization by olivine at hydrothermal conditions

Abstract

The interaction of CO 2 -rich water with olivine was studied using geochemical reaction modelling in order to gain insight into the effects of temperature, acid supply (CO 2 ) and extent of reaction on the secondary mineralogy, water chemistry and mass transfer. Olivine (Fo93) was dissolved at 150 and 250ºC and p CO 2 of 2 and 20 bar in a closed system and an open system with secondary minerals allowed to precipitate. The progressive water–rock interaction resulted in increased solution pH, with gradual carbonate formation starting at pH 5 and various Mg-OH and Mg-Si minerals becoming dominant at pH>8. The major factor determining olivine alteration is the pH of the water. In turn, the pH value is determined by acid supply, reaction progress and temperature.