Research status on the sequestration of carbon dioxide by direct aqueous mineral carbonation
Year: 2001
Type: conference-paper
Abstract: Direct aqueous mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable, solid final form. The process utilizes a solution of distilled water, or sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of magnesium carbonate (MgCO3) in a single unit operation. Mineral reactivity has been increased by pretreatment of the minerals. Thermal activation of serpentine can be achieved by heat pretreatment at 630 C. Carbonation of the thermally activated serpentine, using the bicarbonate-bearing solution, at T=155 C, PCO2=185 atm, and 15% solids, achieved 78% stoichiometric conversion of the silicate to the carbonate in 30 minutes. Recent studies have investigated mechanical activation as an alternative to thermal treatment. The addition of a high intensity attrition grinding step to the size reduction circuit successfully activated both serpentine and olivine. Over 80% stoichiometric conversion of the mechanically activated olivine was achieved in 60 minutes, using the bicarbonate solution at T=185 C, PCO2=150 atm, and 15% solids. Significant carbonation of the mechanically activated minerals, at up to 66% stoichiometric conversion, has also been achieved at ambient temperature (25 C) and PCO2 ={approx}10 atm.
Authors: William K. O’Connor, David C. Dahlin, David N. Nilsen, Stephen J. Gerdemann, G.E. Rush, Richard P. Walters, Paul C. Turner
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W1604697643