the minimum fluidization velocity is decreased with increasing sound frequency from 50 to 150Hz, and then increased with increasing sound frequency from 150 to 400 Hz. For sound frequency being below 150 Hz, it can be found that acous- tic energy enhances the fluidized quality continuously because the sound energy is proportional to sound frequency. For SiO2 particles, numerous large agglomerates generate in the fluidization process. The increased sound energy breaks up significantly bubbles and large agglomerates at different bed temperatures.