2007 年 115 巻 1343 号 p. 443-446
Small amounts of inorganic salts like sodium carbonate and calcium acetate were used as impregnants to pulverized limestone, which was then calcined in a powder-particle fluidized bed (PPFB) in nitrogen atmosphere at ambient pressure. Impregnation of 6-μm limestone with 1 mass% sodium carbonate and 1 mass% calcium acetate lowered the decomposition temperature by 30 K, making a 10% increase of calcination conversion at 1073 K. Additive impregnation involving calcium acetate produced macropores of larger than 50 nm in the reactant powders. Calcination with additive impregnation at 1073 K broadened the size of pores of the calcines to larger ones, newly producing 10-100 nm pores. These changes enhanced the ultimate moisture absorptivity by up to 20% as compared to the case without additive impregnation. However, calcination at 1173 K improved only the initial absorption rate.
