THE USE OF A HIGH LIMESTONE CONTENT MINING WASTE AS A SORBENT FOR CO2 CAPTURE

In this work, a high limestone content waste was evaluated as a potential material for CO2 capture. The influence of calcination conditions on the CO2 capture capacity was evaluated using 5 cycles of calcination-hydration-carbonation reactions. A Central Composite Design of Experiments was set using calcination temperatures and time as variables. The response evaluated was the CO2 capture measured by thermogravimetric analysis. The results indicate that both calcination temperature and time influence the CO2 capture capacities in the initial cycles but, after a large number of cycles, the effect becomes less relevant. The optimum calcination temperature did not change significantly between cycles - about 893 °C in the first and 850 °C in the fourth cycle. However, the optimum calcination time decreased from 40.1 min in the first to 22.5 min in the fourth cycle. The maximum CO2 capture capacity declines over the reaction cycles due to the sorbent sintering, which becomes more noticeable. Moreover, the waste used in this work is suitable for separating CO2 from flue gas, achieving more than 0.2 g/g of capture capacity after five cycles.