CO2 mineral sequestration by using blast furnace slag: From batch to continuous experiments

Abstract

CO2 mineral sequestration is a promising strategy to combat global warming. Indirect CO2 mineral sequestration was proposed in our previous study by using blast furnace slag as feedstock. As the continuity of this research, the continuous experiment process was carried out in a self-designed rotary kiln, and the results were compared with those of the batch experiment. The results showed that several problematic situations, such as the formation of kiln rings, insufficient mass, and heat transfer, occurred in the continuous experiment. A “returning charge” operation by adding an inert component into the feedstock was suggested for the prevention of ring formation and achieved good results. The reaction conditions for the continuous experiment were harsher than those of the batch experiment due to the scale-up effects. Preliminary analysis of CO2 net-emission reduction was conducted based on the continuous experimental results. It was shown that the net reduction of CO2 emissions amounted to 36 kg for 1000 kg of blast furnace slag processed. The results demonstrated in this study can act as guidance for pilot- or industrial-scale applications of indirect CO2 mineral sequestration technologies, especially for process parameter optimization and equipment design.