Modified phosphate ceramics for stabilization and solidification of salt mixed211 wastes

摘要

Novel chemically bonded phosphate ceramics have been investigated for211u001estabilization and solidification of chloride and nitrate salt wastes. Using low-211u001etemperature processing, we stabilized and solidified chloride and nitrate 211u001esurrogate salts (with hazardous metals) in magnesium potassium phosphate ceramics 211u001eup to waste loadings of 70-80 wt.%. A variety of characterizations, including 211u001estrength, microstructure, and leaching, were then conducted on the waste forms. 211u001eLeaching tests show that all heavy metals in the leachant are well below the EPAs 211u001euniversal treatment standard limits. Long-term leaching tests, per ANS 16. 1 211u001eprocedure, yields leachability index for nitrate ions > 12. Chloride ions 211u001eare expected to have an even higher (i.e., better) leachability index. Structural 211u001eperformance of these final waste forms, as indicated by compression strength and 211u001edurability in aqueous environments, satisfies the regulatory criteria. Thus, 211u001ebased on the results of this study, it seems that phosphate ceramics are viable 211u001eoption for containment of salt wastes.