Aqueous carbonation of peridotites for carbon utilisation: a critical review.

ABSTRACT

Peridotite and serpentinites can be used to sequester CO2 emissions through mineral carbonation. Olivine dissolution rate is directly proportional with temperature, presence of CO2, surface area of mineral particles and presence of ligands and is inversely proportional to pH. Olivine dissolution is better under air flow and increases seven times when rock-inhibiting fungus (Knufia petricola) is used. Olivine dissolution retards as silica layers form during reaction. Sonication, acoustic and concurrent grinding using various grinding medias have been used to artificially break these silica layers and achieve high magnesium extraction. Wet grinding using 50 wt.% ethanol enhanced CO2 uptake of dunite 6.9 times and CO2 uptake of harzburgite by 4.5 times. The best economical process is single-stage concurrent grinding at 130 bar, 185 °C, 15 wt.% solids and 50 wt.% grinding media (zirconia) using 0.64 M NaHCO3. Ratio of grinding media to feed should not be less than 31. Yield increases with temperature, pressure, time of reaction, pH and rpm and using additives and grinding media and reducing particle size. This review aims to investigate the progress from 1970s to 2021 on aqueous mineral carbonation of olivine and its naturally available rocks (harzburgite and dunite). This paper comprehensively reviews all aspects of olivine carbonation including olivine dissolution kinetics, effects of grinding and concurrent grinding, thermal activation of olivine feedstock (dunites and harzburgites) as well as chemistry of olivine mineral carbonation. The effects of different reaction parameters on the carbonation yield, role of mineral carbonation accelerators and costs of mineral carbonation process are discussed.