Silica white obtained from rice husk in a fluidized bed

In this paper, silica white, which is obtained from rice husk in a fluidized bed, is investigated. First, the experiments are carried out in the cold fluidized bed of 90-mm interior diameter (I.D.). The experimental results show that the ash mixed with a little rice husk can be fluidized when U-g is within the range of 0.18-0.316 m/s. Then, the experiments of combustion of rice husk are investigated in the fluidized bed of 84 mm I.D. The experimental results show that the combustion occurs in the dense zone of the fluidized bed. The ash in the dense zone is easily purified to obtain the SiO2 powder. The quality of silica white sampled from the dense phase zone is higher than that of GB-precipitated silica and approaches that of pyrogenic silica except for specific surface area and iron content. (C) 2001 Elsevier Science B.V. All rights reserved.