The effect of chemical composition on the PCT durability of mixed waste glasses from wastewater treatment sludges

Conference · Wed Jan 25 04:00:00 EST 1995

OSTI ID:244574

Resce, J L; Ragsdale, R G; Overcamp, T J ^[1]; Bickford, D F; Cicero, C A ^[2]

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1. Clemson Univ., SC (United States)
2. Savannah River Technology Center, Aiken, SC (United States)

An experimental program has been designed to examine the chemical durability of glass compositions derived from the vitrification of simulated wastewater treatment sludges. These sludges represent the majority of low-level mixed wastes currently in need of treatment by the US DOE. The major oxides in these model glasses included SiO{sub 2}, Al{sub 2}O{sub 3}, B{sub 2}O{sub 3}, Na{sub 2}O, CaO and Fe{sub 2}O{sub 3}. In addition, three minor oxides, BaO, NiO, and PbO, were added as hazardous metals. The major oxides were each varied at two levels resulting in 32 experimental glasses. The chemical durability was measured by the 7-Day Product Consistency Test (PCT). The normalized sodium release rates (NRR{sub Na}) of these glasses ranged from 0.01 to 4.99 g/m{sup 2}. The molar ratio of the glass-former to glass-modifier (F/M) was found to have the greatest effect on PCT durability. Glass-formers included SiO{sub 2}, Al{sub 2}O{sub 3}, and B{sub 2}O{sub 3}, while Na{sub 2}O, CaO, BaO, NiO, and PbO were glass-modifiers. As this ratio increased from 0.75 to 2.0, NRR{sub Na} was found to decrease between one and two orders of magnitude. Another important effect on NRR{sub Na} was the Na{sub 2}O/CaO ratio. As this ratio increased from 0.5 to 2.0, NRR{sub Na} increased up to two orders of magnitude for the glasses with the low F/M ratio but almost no effect was observed for the glasses with the high F/M ratio. Increasing the iron oxide content from 2 to 18 mole% was found to decrease NRR{sub Na} one order of magnitude for the glasses with low F/M but iron had little effect on the glasses with the high F/M ratio. The durability also increased when 10 mole percent Al{sub 2}O{sub 3} was included in low iron oxide glasses but no effect was observed with the high iron glasses. The addition of B{sub 2}O{sub 3} had little effect on durability. The effects of other composition parameters on durability are discussed as well.

• Research Organization: Westinghouse Savannah River Co., Aiken, SC (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC09-89SR18035
• OSTI ID: 244574
• Report Number(s): CONF-950216--161; ON: DE96011209
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
36 MATERIALS SCIENCE
ALUMINIUM OXIDES
BARIUM OXIDES
BORON OXIDES
CALCIUM OXIDES
CHEMICAL COMPOSITION
CORROSION RESISTANCE
GLASS
IRON OXIDES
LEAD OXIDES
LOW-LEVEL RADIOACTIVE WASTES
NICKEL OXIDES
RADIOACTIVE WASTE PROCESSING
SAVANNAH RIVER PLANT
SILICON OXIDES
SLUDGES
SODIUM OXIDES
VITRIFICATION