Recycling of Coal Fly Ash by Ceramic Processing

Title: Recycling of Coal Fly Ash by Ceramic Processing
Author(s): Monteiro
Paper category : conference
Book title: International RILEM Conference on the Use of Recycled Materials in Building and Structures
Editor(s): E. Vázquez, Ch. F. Hendriks and G.M.T. Janssen
Print-ISBN: 2-912143-52-7
e-ISBN: 2912143756
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 982 - 987
Total Pages: 6
Nb references: 12
Language: English

Abstract: Coal fly ash was used as raw material for the preparation of ceramic materials by a
conventional powder technology route. Powder compacts were made from as-received fly ash,
from calcined fly ash and from powder mixtures having 90% of calcined fly ash plus a low-cost
mineral as additive (dolomite, CaCO3.MgCO3). The compacts were sintered in air at
temperatures between 900 and 1300ºC for 2h.
The effects of the processing parameters on the densification, microstructural development
and properties of the ceramic bodies were investigated. The unburned carbon present in the
as-received fly ash inhibited densification due to gas formation during firing, resulting in an
increased porosity. A maximum density of ~2.6 g cm -3 was achieved at a sintering
temperature 1050-1100ºC, either for compacts prepared from 100 % calcined fly ash or for
compacts containing 10 wt% dolomite. The addition of dolomite caused the formation of an
increased amount of anorthite and of liquid phase. The density, thermal expansion coefficient
and the modulus of rupture of the densest fly ash-based ceramic materials are identical to
those exhibited by some traditional ceramics used in civil construction.
The present results indicate a convenient way to treat coal fly ash, transforming it into
useful ceramic products via a simple and cost effective powder technology and sintering
route.

Online publication: 2004-09-29
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143756.108