Comparison of glassy slag waste forms produced in laboratory crucibles and in a bench-scale plasma furnace

Abstract

Glassy slags (vitro-ceramics) are glass-crystal composites, and they are composed of various metal oxide crystalline phases embedded in an aluminosilicate glass matrix. Glassy slags are developed to complement homogenous glass waste forms in implementing Minimum Additive Waste Stabilization (MAWS). Glassy slags with compositions developed in crucible melts at Argonne National Laboratory (ANL) were successfully produced in a bench-scale Retech plasma centrifugal furnace (PCF) by MSE, Inc. Detailed examinations of these materials showed that the crucible melts and the PCF produced similar glass and crystalline phases. The two sets of glassy slags exhibited similar chemical durability in terms of normaliied releases of their major components. The slags produced in the PCF furnace using metals were usually less oxidized, although this had no effect on the corrosion behavior of the major components of the slags. However, the normalized release rate of cerium was initially lower for the PCF slags. This difference diminished with time as the redox states of the metal oxides in slags began to be controlled by exposure to air in the tests. Thus, the difference in cerium release due to the differences in slag redox state may be transitory. The cerium solubility is a complex function of redox state and solution pH and Eh.

Minimum Additive Waste Stabilization Using Vitreous Ceramics Interim Progress Report October 1994-September 1995

“…Alternatively, vitreous ceramics can be made such that most of the hazardous and radioactive compounds are concentrated in crystalline phases. Vitreous-ceramic compositions developed through crucible melts were also produced in a Retech pilot-scale plasma centrifugal furnace at Ukiah, California, with up to 100% waste loadings (Feng 1994d). These successful campaigns demonstrate the processibility of vitreous ceramics.…”