Beyond carbon capture towards resource recovery and utilization: fluidized-bed homogeneous granulation of calcium carbonate from captured CO2.

Atmospheric carbon dioxide (CO 2) imbalance due to anthropogenic emissions has direct impact in climate change. Recent advancements in the mitigation of industrial CO 2 emissions have been brought about by a paradigm shift from mere CO 2 capture onto various adsorbents to CO 2 conversion into high value products. The present study proposes a system which involves the conversion of CO 2 into high purity, low moisture, compact and large CaCO 3 solids through homogeneous granulation in a fluidized-bed reactor (FBR). In the present study, synthetic solutions of potassium carbonate (K 2 CO 3) and calcium hydroxide (Ca(OH) 2) were used as sources of carbonate and precipitant, respectively. The effects of the degree of supersaturation (S) as chemical loading and influx flow rate (Q T) as hydraulic loading on CaCO 3 granulation efficiency were investigated. In the study, S was varied from 10.2 to 10.8 and Q T from 40 to 80 mL min−1 while the operating pH and calcium-is-to-carbonate molar ratio ([Ca2+/[CO 3 2−) were set at 10 ± 0.2 and 1.50, respectively. Results showed that carbonate ions end product distribution had a highest carbonate granulation efficiency at [Carbonate] G of 95–96% using S of 10.6 and Q T of 60 mL min−1. Characterization of the granules confirmed high purity calcium carbonate. Overall, the transformation of industrial CO 2 emissions into a valuable solid product can be a significant move towards the mitigation of climate change from anthropogenic emissions. Image 101088 • Carbon dioxide was recovered by calcium carbonate granulation. • Calcium carbonate removal and granulation efficiencies exceeded 95%. • Effects of supersaturation and cross-sectional loading on granulation were examined. • Physic-chemical characteristics of the recovered granules were analyzed. [ABSTRACT FROM AUTHOR]