PRODUCTION OF LOW WATER ABSORPTIVE GRANULAR PERLITE FOR BUILDING MATERIAL FORMED BY USING PERLITE AND PITCHSTONE

摘要

PURPOSE: To obtain foamed products having the quality equiv. to or higher than the quality of the conventional obsidian granular foamed perlite by preheating perlite or pitchstone subjected to grain size adjustment under specific conditions and foaming this perlite or pitchstone. ;CONSTITUTION: The perlite or pitchstone subjected to the grain size adjustment in a specified range is preheated by a heater to room temp. and 100 to 400°C and is foamed in plural heating zones, i.e., at 900 to 1100°C in the first zone, successively from a raw material supply side, at 850 to 1100°C in the second zone and at 500 to 1000°C in the third zone. The foaming time (in-furnace stagnation time) is so specified to 30 seconds to 20 minutes that the apparent bulk density of the foamed products attains 0.15 to 0.30g/cm³, the water absorption 35 to 80% and the particle size 0.5 to 1.0g/cm³. A preheating unit 1 in Fig. has mirror finished stainless steel pipes 2 and is mounted with an electric furnace 3. A raw material container 4 is a hopper and is mounted with a vibration feeder 5. A foaming furnace 7 is connected after a venting and drying machine 6. Tubular stainless steel pipes 8, the electric furnace 9 and the venting and drying machine 10 are connected.;COPYRIGHT: (C)1995,JPO