CO2 Capture by Using Blended Hydraulic Slag Cement via a Slurry Reactor

Abstract

Mitigation and adaptation are viable strategies for resolving climate change issues which may pose significant challenges to both ecosystems and human populations around the world. Aqueous carbonation is a promising process for mitigating CO 2 , due to the permanent storage of gaseous CO 2 into carbonate precipitations (CaCO 3 and/or MgCO 3 ). In this study, aqueous carbonation of blended hydraulic slag cement (BHC) for CO 2 sequestration was investigated and evaluated under various operating conditions, i.e., different reaction temperatures and CO 2 concentrations, in a slurry reactor. The suspension BHC slurry was strongly alkaline (pH ~11.4) before carbonation, whereas the pH of the slurry dropped rapidly to nearly a weakly acidic solution (i.e., pH ~6.3) after introducing CO 2 gas into the reactor. The results show that the maximum CO 2 capture capacity was 181 g CO 2 per kg BHC at a reaction time of 120 min, a CO 2 concentration of 10%, and a gas flow rate of 2.5 L/min at 65°C. The reaction temperature slightly influenced the carbonation conversion of BHC, with an increasing temperature resulting in relatively higher conversion. In addition, the SEM and XRD results suggest that the BHC should be carbonated with CO 2 to form CaCO 3 in a slurry reactor. It was thus concluded that the CO 2 could be successfully captured by the carbonation of BHC in this manner. Furthermore, the experimental data were utilized to determine the rate-limiting mechanism based on the shrinking-core model (SCM), which was validated by the observations of SEM images. The SCM results indicate that the overall carbonation reaction of BHC in a slurry reactor was controlled by the ash-layer diffusion mechanism.

Comparative Life Cycle Assessment (LCA) of Accelerated Carbonation Processes Using Steelmaking Slag for CO2 Fixation

“…In contrast, the electricity used for the heating process in scenarios 4, 5, and 6 is about 20.1%, 18.7% and 18.6%, respectively. It was noted that increasing the reaction temperature would accelerate the carbonation rate and improve the carbonation conversion of steelmaking slags; however, it also would generate additional CO 2 emission and reduce the overall CO 2 capture capacity (Chang et al, 2012b;. On the other hand, in the case of indirect carbonation, the stirring process and pumps are found to account for more than 50% of total energy use.…”

Influence of Supercritical CO2 on the Mobility and Desorption of Trace Elements from CO2 Storage Rock Sandstone and Caprock Shale in a Potential CO2 Sequestration Site in Taiwan

“…As such, several projects were in the pipeline demonstrating its viability (Leung et al, 2014). Another area of interests in CCS studies was via permanent CO 2 sequestration, in which CO 2 is chemically stored in solid carbonates by carbonation of minerals (Huijgen and Comans, 2003;Chang et al, 2012;Pan et al, 2015). Direct mineral carbonation was investigated as a process to convert gaseous CO 2 into a geologically stable, solid final form utilizing a solution of sodium bicarbonate, sodium chloride, and water, mixed with a mineral reactant, such as olivine or serpentine (O'Connor et al, 2001).…”

NO Reduction Scale of Three Typical Chinese Coals during Oxy-Coal Combustion

“…Compared to the traditional air combustion combined with the ammonia adsorption CO 2 recovery method, oxy-coal combustion is more economical . Oxy-coal combustion has become one of the most applicable technologies in future for its ability to control the pollutants cheaply and effectively (Chan et al, 2012;Pan et al, 2012).…”