PRODUCTION OF SYNTHETIC SILICA POWDER AND PRODUCTION OF SILICA GLASS MOLDED FORM

Japanese Patent JP3735887

B2

PURPOSE: To prevent the development of fine bubbles in the resultant molded form during melt forming of silica gel powder and increase the bulk density of the powder to be charged into a crucible by heat treating silica gel powder while continuously feeding it via one end of a rotary kiln.
CONSTITUTION: First, dry silica gel powder 10-1000μm in particle diameter is obtained by drying and pulverizing a get obtained by hydrolysis or gelation of a tetraalkoxysilane. Secondly, the silica gel powder is heat-treated at 200-1100°C in a core pipe made of quartz while continuously feeding it via one end of the core pipe in a rotary kiln and the final temperature is brought to 900-1100°C at a rate of temperature rise of ≤1000°C/h. The heat treatment is conducted under clean air or an oxygen-contg. gas atmosphere. A gas feed nozzle is provided above the powder feed nozzle, the tilt angle of the rotary kiln is set at ≤3°, there is afforded a doughnut-shaped shuttering board and the diameter of the silica gel feed port is made smaller than that of the discharge port to ensure silica get backflow not to occur.

Yoshio Suguro
Oishi
Yuji Maeda

JP10588995A

January 18, 2006

April 28, 1995

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Mitsubishi Chemical Corporation

C01B33/18; C03B20/00; B01J6/00; C03B8/02; C03B19/12; C03C3/06; F27B7/28; F27B7/34; (IPC1-7): C01B33/18; C03B19/12; C03B20/00; F27B7/28; F27B7/34

JP6042876A
JP5004925B2
JP2500972A
JP6024728A
JP6191824A
JP8104531A
JP9156918A

Hasegawa Soji

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