Abstract
Porous quicklime powder is produced from 5 μm limestone particles in a Powder-Particle Fluidized Bed (PPFB). PPFB is a new fluidization technique in which agglomerative fine particles adhere onto the surface of the fluidized coarse particles, and are co-fluidized in the bed. For 5-μm limestone calcined with dry air at 1073 to 1223 K, the PPFB yields the lime powder with BET specific surface areas of 15 to 60 m2/g, depending on the residence time of gas in the PPFB. Measurement of the total pore volume of produced lime reveals a maximum value of 0.178 cm3/g, which is much higher than those obtained by conventional methods. However, the pore volume of the lime produced at 1173 K with gas containing CO2 is almost constant, regardless of the residence time of gas. This can be caused from the fact that the CO2 effect on mild sintering surpasses the temperature-promoted sintering. From this study, the lime powder that has very large BET specific surface and large pore volume can be produced by this method.
