| 摘要 |
PURPOSE:To improve the shape and density of a minute spherical particle, by performing two-stage spray drying treatment for drying a sol, gel or suspension of inorg oxide or hydroxide at a low drying speed before drying the same at a high speed. CONSTITUTION:A sol, gel or suspension of inorg oxide or hydroxide with a viscosity of about 500cp or less, pref., 50cp or less is sprayed by using a gas- liquid two-fluid mixture and slowly dried at 10-100 deg.C at drying speed of 0.02k moisture/sec.kg solid or less, pref., 0.016kg moisture/sec.kg solid to obtain a powder with moisture content of about 12% or more. This powder is contacted with gas at 110-400 deg.C, pref., 150-300 deg.C and dried at a drying speed of 0.04kg moisture/sec.kg solid or more, pref., 0.05kg moisture/sec.kg solid to obtain a spherical particle with an average particle size of 0.5-30mum.
|
