The Manufacturing Process of the Fine Shirasuballoons Using a Fluidized Bed Furnace

Abstract

A new method of production of fine Shirasuballoons from glassy volcanic fragments, named Shirasu, was developed. Finer Shirasuballoons were required to replace conventional Shirasuballoons. However, the pulverized Shirasu is easily agglomerated and clogged; therefore, they cannot be supplied continuously to the furnace. It was shown that the flowability and the floodability of the pulverized Shirasu were improved by a dry surface treatment. The fine Shirasuballoons of mean particle sizes under 20μm were successfully prepared in a fluidized bed furnace by rapid heating of the pulverized Shirasu after the surface treatment. The foaming characteristics of the fine Shirasuballoons depended on the preheat treatment of the pulverized Shirasu in the temperature range of 150-300°C; an increase in pre-heat temperature resulted in decrease in the expansion ratio of the fine Shirasuballoons.