Effects of sulfur and potassium on rhenium retention in simplified low-activity waste glass

Abstract

Four consecutive sets of simplified glass feed compositions were designed and tested both with and without rhenium (Re) additions. The objectives of this study concerning the effects of sulfur (S, expressed as SO3 in glass) and potassium (K, K2O in glass) on Re retention during melting of low-activity glass feeds were twofold: (i) design a simplified system that reproduces the Re behavior observed in fully simulated feeds, the system will be used to investigate mechanisms related to Re incorporation into glass and (ii) Provide experimental data that support or reject the mechanisms that have been proposed to explain the previous findings from scaled melter and crucible tests. The simplified system of alkali borosilicate glass feeds in this study successfully reproduced the published results from the melter tests with fully simulated feeds on the effects of S and K on Re behavior. The present study also provides experimental evidence on the combined effect of S and K. The findings from this study regarding the effects of S and K on Re retention also are explained by the previously proposed mechanism on the effect of sulfate on Re retention and by the effect of component concentrations and activity coefficients of volatile species on its vapor pressure, also discussed in a recent study.