Solution-Derived, Chloride-Containing Minerals as a Waste Form for Alkali Chlorides

Journal Article · Mon Oct 01 04:00:00 EDT 2012 · Journal of the American Ceramic Society, 95(10):3115-3123

DOI:https://doi.org/10.1111/j.1551-2916.2012.05363.x· OSTI ID:1054459

Riley, Brian J; Crum, Jarrod V; Matyas, Josef; McCloy, John S; Lepry, William C

Sodalite [Na8(AlSiO4)6Cl2] and cancrinite [(Na,K)6Ca2Al6Si6O24Cl4] are environmentally stable, chloride-containing minerals and are a logical waste form option for the mixed alkali chloride salt waste stream that is generated from a proposed electrochemical separations process during nuclear fuel reprocessing. Due to the volatility of chloride salts at moderate temperatures, the ideal processing route for these salts is a low-temperature approach such as the sol-gel process. The sodalite structure can be easily synthesized by the sol-gel process; however, it is produced in the form of a fine powder with particle sizes on the order of 1–10 µm. Due to the small particle size, these powders require additional treatment to form a monolith. In this study, the sol-gel powders were pressed into pellets and fired to achieve > 90% of theoretical density. The cancrinite structure, identified as the best candidate mineral form in terms of waste loading capacity, was only produced on a limited basis following the sol-gel process and converted to sodalite upon firing. Here we discuss the sol-gel process specifics, chemical durability of select waste forms, and the steps taken to maximize chloride-containing phases, decrease chloride loss during pellet firing, and increase pellet densities.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1054459
• Report Number(s): PNNL-SA-86321; AF5805000
• Journal Information: Journal of the American Ceramic Society, 95(10):3115-3123, Journal Name: Journal of the American Ceramic Society, 95(10):3115-3123
• Country of Publication: United States
• Language: English

Related Subjects

cancrinite
electrochemical
sodalite
sol-gel