【Special Issues: Recycling and Resourse Recovery of Inorganic Solid Wastes】
Preparation of Glass-ceramics from Inorganic Wastes and their Properties
Kiyoshi Okada
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology
（2-12-1 O-okayama, Meguro-ku, Tokyo, 152-8552 Japan）
Abstract
Various inorganic wastes are generated by industrial and everyday human
activities. In this review, the preparation and properties of glass-ceramics
from wastes（Kira）generated from refining of silica sand and kaolin clay
as plate glass and porcelain raw materials are described as an example
of the conversion of wastes to functional ceramics. Since the melting of
Kira reguires heating at about 1,600℃, glasses were prepared at ≦1,400℃
using mixtures of Kira with limestone, dolomite or paper sludge ash（PS）.
They were ground to powder, pressed to form a pellet, then crystallized
at 900-1,100℃ to produce glass-ceramics. The resultant glass-ceramics
were shiny and white in color. Major crystalline phases that formed in
the glass-ceramics were wollastonite（CaSiO3）in the Kira-limestone sample,
anorthite（CaAl2Si2O8）or diopside（CaMgSi2O6）in the Kira-dolomite samples,
and quartz solid solution（Mgx/2AlxSi1-xO2）or cristobalite（SiO2）in the
Kira-PS samples. The resultant glass-ceramics show excellent mechanical
properties and chemical durability for acid solution.
Key words: glass-ceramics, waste from plate glass raw material, waste of porcelain
raw material, paper sludge ash