Parameters affecting the conversion ratio of lime to calcium carbonate in mineral carbonation reaction in clay-free sand and calcium efficiency

Abstract

Mineral carbonation based on lime (Ca(OH)2) and carbon dioxide (CO2) is a carbon sequestration and also a soil improvement method. This paper investigates the effects of varying Ca(OH)2 (1%, 5%, and 10%) and water ratios (6%, 7%, 8%, 9%, and 10%), and mineral carbonation duration (1 hr, 3 hrs, 5 hrs, and 7 hrs) on the conversion of lime to calcium carbonate in clay-free sand. Two different silicon sand samples which have different grain sizes were used in the experiments. Reacted lime ratio, used lime ratio, and unused Ca2+ ratio were calculated. The lime fixation point was determined as 1% by the total weight of the soil. The average carbonation ratio at the lime fixation point was found to be 84.10 ± 7.75%, which was the highest value. As the lime in the soil increased, the reacted lime and the use of lime decreased. The appropriate water ratio was determined as 6%. Fines supported the conversion of more lime to calcium carbonate. The conversion of lime to calcite was completed in the first few minutes (short-term), but the strength of the lime-treated soil improved over time. The progress of the mineral carbonation reaction in the solid was according to the Dome Principle (DPinC). The conversion of lime to CaCO3 ratio, reacted lime ratio, used lime ratio, and unused Ca2+ ratio was calculated for the first time.