— Usually, limestone (CaCO 3) and lime (CaO) are used as Ca(OH) 2 sources thanks to their abundance and low cost. Due to its low solubility, limestone needs to be pulverized in order to be used in the FGD process, adding cost and energy expenditure to the process. Kikkawa et al. (2002) tried to scrub SO 2 from FGD without limestone size …