【Special Issues: Recycling and Resourse Recovery of Inorganic Solid Wastes】
Hydrothermally Solidified Functional Materials from Inorganic Wastes
Norifumi Isu* and Hideki Ishida*
* R&D Center, INAX Corp.
† Correspondence should be addressed to Norifumi Isu:
（3-77 Minatocho, Tokoname, Aichi, 479-8588 Japan）

Abstract
Hydrothermal reactions were investigated in order to find recycling technologies for inorganic wastes. The base materials used were waste soil containing kaolinite, and water purification sludge containing amorphous aluminum hydroxide derived from a coagulant agent. Each type of waste with a small amount of calcium hydroxide was formed by uniaxial pressing at 30 MPa, followed by hydrothermal treatment at 180 to 220℃ under saturated steam pressure. The nano-size reaction products were formed through a hydrothermal reaction. Hydrogarnet was formed using waste soil, while amorphous hydrates containing Al, Si, Fe and Ca was formed using sludge. The formation of these nano-size hydrates resulted in strength development and the formation of mesoporous structure, suggesting applications for humidity controlling materials or adsorption materials.

Key words: inorganic waste, hydrothermal solidification, porous, strength, adsorption