Abstract
Finer hollow microballoon is expected to improve the chemical and physical properties of conventional Shirasuballoon, glassy balloon and expanded perlite. It is shown that fine microballoons of particle sizes under 20μm and bulk specific volume above 2cm3/g are desired by summarizing those of the conventional Shirasuballoons and glassy balloons. Fine Shirasuballoons are prepared from five kinds of vitric volcaniclastic materials named as Shirasu (or Hakudo); Shinjo-Shirasu, Kakuto-Shirasu, Yoshida-Shirasu, Nakano-Hakudo and Biei-Hakudo. The five kinds of vitric volcaniclastic materials are milled and expanded using a fluidized bed furnace. Fine Shirasuballoons within the above regions are successfully prepared except Shinjo-Shirasu by choosing appropriate heating conditions, which are different among the milled powders. Preparation conditions and some properties of fine Shirasuballoons are presented.
