| 摘要 |
<p>PURPOSE:To form a lightweight aggregate which has a superior-quality film and is excellent in strength by mixing vitreous volcanic rock with incineration ashes of sludge and calcining the mixture in a range within the specified temp. CONSTITUTION:Powdery granules obtained by crushing vitreous volcanic rock such as obsidian and perlite are charged at about 10-30% volume ratio into incineration ashes 3 remained after incinerating sludge generated from sewage and burning organic substance contained therein and mixed with each other. This mixture is heated and dried as a granular form and thereafter when it is calcined at 900-1,200 deg.C with a rotary kiln or the like, the surface of the granular material is made to a semi-fused state and simultaneously gas is generated in the inside and therefore foams 4 are formed thereby and softened whole surface are expanded. Furthermore it is taken out from this high-temp. region in the state reached to such a state and cooled with a rotary cooler or the like and made to a beady lightweight aggregate in which a vitreous film 2 is formed on the surface and large quantities of fine independent foams are included to the inside.</p> |
