Vitusite glass-ceramics wasteforms for immobilization of lanthanide wastes generated by pyro-processing.

Glass-ceramic wasteforms containing vitusite (Na 3 Ce(PO 4 ) 2 ) and Ce-rich crystals were investigated to immobilize lanthanide oxide wastes generated by pyro-processing. Controlled crystallization of alkali borosilicate glasses containing small amounts of P 2 O 5 by heating at T >600 °C for 3 h resulted in formation of vitusite as a major crystalline phase with a minor Ce-rich crystalline phase. Lanthanide oxide waste loading was 11.87 wt%. Rare-earth wastes were efficiently immobilized inside the crystalline phases: lanthanide elements such as Ce and Nd constituted ~26 wt% of vitusite and 80 wt% of Ce-rich crystals. Amounts of Ce and Nd ions released in a product consistency test were below the detection limit (0.1 ppm) of inductively coupled plasma atomic emission spectroscopy. Glass-ceramic wasteforms that contain vitusite crystals are good candidates to immobilize lanthanide wastes generated by pyro-processing. [ABSTRACT FROM AUTHOR]