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Speciation in Size and Density Fractionated Fly Ash III. The influence of HCL Leaching on the Glassy Constituents of a High-Ca Fly Ash

Published online by Cambridge University Press:  21 February 2011

E. E. Berry
Affiliation:
Ontario Research Foundation, Sheridan Park, Mississauga, Ontario, Canada, L5K 1B3
R. T. Hemmings
Affiliation:
Ontario Research Foundation, Sheridan Park, Mississauga, Ontario, Canada, L5K 1B3
B. J. Cornelius
Affiliation:
Ontario Research Foundation, Sheridan Park, Mississauga, Ontario, Canada, L5K 1B3
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Abstract

Ash density fractions, separated from a high-Ca fly ash, were leached with 6M HCl at 105°C. The density fractions (<0.79 and >2.85 g.cm−3) selected for leaching have been shown in previous work to consist largely of two different glass types, designated Glass I and Glass II. It was shown that both Glass I and Glass II are leachable to yield solutions containing Al and modifier cations. Acid attack on Glass I appears to involve hydrolysis of Si–O–Al (silalane) bridges along with ion exchange at available non-bridging oxygen sites. Attack on Glass II is more extensive, with both silalane and siloxane bridges being hydrolysed, and ion-exchange occurring at non-bridging oxygens. The products of leaching are aluminosilicates. In the case of Glass I, these remain as pseudomorphic, hollow spheres; whereas, for Glass II, substantial reprecipitation of silica (alumina) gel was found.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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References

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