Cement kiln dust/rice husk ash as a low temperature route for wollastonite processing

Abstract

eco-friendly and valuable commercial wollastonite based ceramics have been obtained from the most hazardous industrial and agrowastes (cement kiln dust and rice husk ash) by reactive crystallization-sintering. Different batch compositions from cement kiln dust (ckD) with varying amounts of rice husk ash (rHA) were wet mixed, dried, grounded and sieved. then, all batches were uniaxially pressed and fired at different temperatures (1100-1200c). Phase composition, microstructure, densification parameters, and mechanical properties of the obtained fired specimens were investigated. the results showed that wollastonite based ceramics were synthesized successfully at 1100c without addition of any mineralizers. on the other hand, a considerable saving in time and heat energy were realized when an amorphous rHA silica was used instead of its other crystalline varieties. this was related to the higher reactivity of the amorphous rHA silica and its high specific surface area. the presented work made possible not only to overcome the environmental pollution ensuing from the accumulation of these industrial and agrowastes but also, to valorize and find added value to these residues. conversion the latter into useful wollastonite-based ceramics with appropriate technology and environmental properties, allows the potential application in several fields. Hence, economic benefits will accrue to the producers and thus to the national economy.