CO₂ Sequestration Potential of Steel Slags at Ambient Pressure and Temperature

Abstract

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 hydratedmatrixes 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.

CO2 Capture by Accelerated Carbonation of Alkaline Wastes: A Review on Its Principles and Applications

“…One way to avoid some of these drawbacks is to utilize alkaline waste residues. Table 2 summarizes the example of industrial alkaline solid wastes, e.g., coal-and oil shale-fired power plants (Uibu et al, 2009b;Uibu and Kuusik, 2009a;Uibu et al, 2011), steelmaking slag (Huijgen et al, 2005c;Bonenfant et al, 2008; Huijgen et al, 2005c;Bonenfant et al, 2008;Eloneva et al, 2008b;Kodama et al, 2008;Baciocchi et al, 2009b;Doucet, 2010;Chang et al, 2011a, b Air pollution control (APC) residue Khaitan et al, 2009;Yadav et al, 2010 Sludge (incinerator) ash Sewage sludge incinerator ash (SSA) Steel wastewater sludge (SWS) Paper sludge incinerator ash (PSIA) Gunning et al, 2010 Paper pulping and mill waste…”

“…CaO), residues from APC (Ca content up to 35%) and bauxite (4.8% Ca), cement kiln dust (~34-50% wt. CaO), oil-shale waste (CaO content up to 50%), and fly ash (53% CaO) from municipal solid waste incinerators (Huijgen et al, 2005b;Bonenfant et al, 2008;Eloneva et al, 2008a;Baciocchi et al, 2009c; 2011a). Industrial alkaline solid wastes such as sources of calcium or magnesium oxide are ideal CO 2 sequestration materials due to their availability and low cost.…”

“…Therefore, CO 2 capture by carbonating the steelmaking slags could be an interesting option for reducing CO 2 emissions from the steel plant. In recent years, accelerated carbonation of steelmaking slags has been progressively tested to assess the CO 2 capture potential of this material (e.g., Huijgen et al, 2005c;Bonenfant et al, 2008;Teir, 2008;Eloneva et al, 2008a;Kodama et al, 2008;Costa, 2009;Wang and Yan, 2010;Chang et al, 2011a, b;De Windt et al, 2011). Fig.…”

“…It was suggested that some characteristic time, often longer than the time constant for the overall process, is needed to achieve a new equilibrium (Salminen and Prausnitz, 2007). The carbonate precipitation using steelmaking slag as feedstock should be mainly calcite (CaCO 3 ) (Bonenfant et al, 2008;Eloneva et al, 2008a;Costa, 2009;Wang and Yan, 2010;Chang et al, 2011a, b). The crystal volume of calcium carbonate is approximately 11.7 percent more than that of calcium hydroxide (Ishida and Maekawa, 2000).…”

Aqueous Carbonation of Steel Slag: A Kinetics Study

“…6) Mineral carbonation can be performed with pure oxides (e.g., CaO, MgO) as well as olivine ((Mg,Fe) 2 SiO 4 ) and serpentine (Mg 3 Si 2 O 5 (OH) 4 )). 7) Industrial solid waste, which includes steel slag, [8][9][10][11][12] cement kiln dust, 13,14) red mud, 15) and coal combustion fly ash, 16,17) has recently attracted the researchers' interest as possible feedstock. These materials are generally in alkaline and rich in calcium oxide.…”