The effect of quench rate on the TCLP and PCT durability of environmental waste glass Page: 4 of 7
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PREPRINT EXTENDED ABSTRACT
Presented at the I&EC Special Symposium
American Chemical Society
Atlanta, GA, September 17-20, 1995
THE EFFECT OF QUENCH RATE ON THE TCLP AND PCT DURABILITY
OF ENVIRONMENTAL WASTE GLASS
J.L. Resce and B.M. Wolff
Environmental Systems Engineering Department
Clemson University, Clemson, SC 29634
A.R. Jurgensen, C.M. Cicero, and D.F. Bickford
Westinghouse Savannah River Company
Aiken, SC 29808
The effect of quench rate and the resulting devitrification on the durability of environmental waste glasses has been
examined for a set of 16 model glasses. The glasses have been derived from a large glass composition space, i.e.
"hyperspace glasses," which were previously developed to serve as a simplified model for studying the durability of glassy
wasteforms which might result from vitrification.' In this study, a subset of this space has been examined for chemical
durability by both the PCT and TCLP tests. This subspace is composed of six variable components Fe2O3, SiO2, A1203,
B203, Na2O, and CaO and three fixed-level components BaO, PbO, and NiO. The sum of the six variable oxides always
total to 95 mole percent, while, BaO and NiO levels are fixed at 2 mole percent each and PbO is 1 mole percent. The
preparation and characterization of these glasses has been previously described.2 Their approximate oxide composition, in
mole percent, is given in Table 1. These glasses can be classified into two groups, those with low and those with higher
levels of Fe203.
The glass melts were cast into molds to produce disks, 40 mm in diameter by 6 mm in height. The disks were then
quenched at two different rates. Glasses quenched at a medium rate were placed directly into a box furnace at 450* C for
30 minutes and the furnace was then turned off. The glasses then cooled to room temperature in about 2 hours. The
glasses quenched at a slow rate were placed in a furnace at 6500 C for 8 hours and then slowly cooled to room
temperature. The crystallinity of the glasses was determined by powder x-ray diffraction so that they could be classified
into three categories: (1) "amorphous," (2) "crystalline," and (3) "more crystalline."
Chemical durability testing was carried out by both the 7-Day Product Consistency Test (PCT) and the TCLP test. The
sodium normalized elemental release rate (NaNRR), in g-m-2-c', was determined from Equation 1,
(1) NaR = CNa
where CN0 is the concentration of elemental sodium in the leachate, in g-m 3; VL is the volume of the leachate; fv. is the
weight fraction of sodium in the original glass; SA is the surface area of the glass; and t is leaching time. The SAs/VL
ratio is assumed to be 1950 m'.
The PCT NaNRR and the TCLP releases of both Ni and Ba for both the low and high Fe2O3 glasses are reported in
Figures 1 and 2, respectively. These results show that there is almost no devitrification with either quench rate for the low
iron glasses and that there is negligible change in durability. For the high iron glasses, however, some of the slow
quenched glasses are significantly more devitrified and crystalline. In some glasses, this increased crystallinity is found to
lower the NaNRR and Ba TCLP durability. TCLP Ni release was negligible in both cases.
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Resce, J.L.; Wolff, B.M.; Jurgensen, A.R.; Cicero, C.M. & Bickford, D.F. The effect of quench rate on the TCLP and PCT durability of environmental waste glass, report, December 1, 1995; Aiken, South Carolina. (digital.library.unt.edu/ark:/67531/metadc624803/m1/4/: accessed January 16, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.