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A Statistical Investigation on Particle to Particle Variation of Fly Ash Using SEM-AIA-EDAX Technique.

Published online by Cambridge University Press:  21 February 2011

L. E. Barta
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
G. VÁmos
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
M. A. Toqan
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
J. D. Teare
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
J. M. BeÉr
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
A. F. Sarofim
Affiliation:
Massachusetts Institute of Technology Cambridge. MA, USA.
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Abstract

Due to the particle to particle variation of coal mineral properties and random coalescence of mineral particles during coal burnout, fly ash particle properties change from particle to particle. The variations of particle properties (e.g. SiO2 content, viscosity) can be mathematically described by random variables. Since bulk analysis of fly ash gives only the mean values of chosen random variables, it is considered insufficient to describe the fly ash behavior either in boiler slagging/fouling or in different concrete structures. SEM-AIA-EDAX technique was used to supply raw data for estimating the distribution functions of particle size and chemical compounds in Texas lignite minerals and fly ash and Eagle Butte fly ash. To determine the volume based size distributions of these samples from their area-based size distributions, Abelian transformation was used. To estimate the distribution functions of CaO and SiO2 contents of the samples, particle area fractions were used. The confidence limits were also calculated for the estimated parameters. By determining the distribution functions of particle viscosity and chemical composition, it was shown that in the case of Texas lignite the coal burnout does not cause significant changes in the mineral matter properties. It was observed that the properties of fly ash depended solely on the mineral matter properties. However, in the Eagle Butte case the coal burnout has a major effect on the fly ash size distribution and its chemical composition.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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