A study of carbon dioxide sequestration has been performed in aqueous electric arc furnace (EAF) and ladle furnace (LF) slag suspensions, in leached hydrated-matrixes, and in leachates to estimate their intrinsic sequestration potential at ambient conditions (temperature of 20 ± 1 °C and atmospheric pressure). The CO 2 sequestration was tested in aqueous suspensions of steel slags at a liquid-to-solid ratio of 10 kg/kg as well as in leached hydrated-matrixes and leachates isolated from these fresh slag suspensions after three consecutive leachings. The sequestration assays were performed at 20 °C with a flow rate of 5 mL/min of a CO 2 concentration of 15.00 vol %. The results have revealed that the CO 2 sequestration capacity of the LF slag suspension (24.7 g of CO 2 /100 g of slag) is 14 times superior to that of the EAF slag suspension. This greater CO 2 sequestration capacity of the LF slag suspension may be associated in large part to its higher content of portlandite, which reacts with CO 2 relative to the EAF slag suspension. Moreover, the separation of hydrated-matrixes and leachates significantly enhanced the CO 2 sequestration capacity of EAF slag while a slight decrease was observed for the LF slags. This may be due to an obstruction of the CO 2 binding sites of LF slag hydrated-matrixes following the accumulation of calcium carbonate. Taken together, these results suggest that EAF and LF slags could be used for the CO 2 sequestration and given a good yield as well in aqueous suspension as in separated matrixes and leachates.
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Bonenfant et al. (2008) studied this question.