Relationship Between Microstructure and Properties of Limestone Calcined Rapidly at High Temperatures

Abstract

The relationship between microstructure and physicochemical properties of limestone including, porosity, bulk density, pore size distribution, specific surface area and activity were studied under the condition of rapid heating from room temperature to 1350–1550 °C. The results showed that complete decomposition of limestone (diameter 12.5–15 mm) at 1350 °C, 1450 °C and 1550 °C took 11.7 min, 9.2 min and 6.9 min, respectively. With the prolongation of calcination, lime porosity first increased and then decreased. The peak value of lime porosity was found roughly at the end of limestone decomposition. The variation of bulk density, however, was just the opposite compared to porosity. When calcination temperature increased, the pore size of lime became larger, and the number of micropores decreased correspondingly; furthermore, while calcination time increased, micropores disappeared fast, and macropores increased rapidly. The specific surface area of lime decreased with prolonged calcination time. The best activity of lime could be obtained with high porosity and high specific surface area at the same time. The maximum activity values of lime were 379 mL, 365 mL and 267 mL at the temperatures of 1350 °C, 1450 °C and 1550 °C, respectively.