الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
Eco-friendly and most valuable wollastonite based ceramics have been
obtained from the most hazardous industrial wastes (Cement kiln dust), as calcia
source, along with rice husk ash (RHA) or quartz sand (Qtz), as silica sources,
through reactive crystallization-sintering.
Different batch compositions of cement kiln dust (CKD) with 30 to 55 wt.% of
RHA or Qtz with an increment of 5wt.%, were wet mixed, dried at 80oC for 24
hrs, then ground and sieved in order to obtain homogeneity of all batches. These
batches were uniaxially pressed, dried at 105oC and then fired at different
temperatures (1100-1250oC).
Phase composition, microstructure, densification parameters, mechanical and
thermal properties of the fired specimens were investigated. The results showed
that α- & β-wollastonite based ceramics were successfully synthesized without
addition of any mineralizers at lower temperatures (1100-1250oC) in comparison
with their synthesis from the pure constituents (>1400oC).
A considerable saving in time and heat energy were found when an amorphous
RHA silica was used instead of crystalline variety (Qtz). This is due to the higher
reactivity of the amorphous RHA silica and its greater surface area.
This work makes it possible not only to overcome the environmental pollution
ensuing from the accumulation of these industrial and agrowaste products but also,
to valorize and find added value to these residues. Conversion the latter into useful
wollastonite-based ceramics with good technology and environmental properties,
allows their potential application in many industries. Hence, economic benefits
will accrue to the producers and thus to the national economy.