Dry-out and low temperature calcination of DST/SST waste blend high temperature melter feed

Abstract

Reprint of historical document PVTD-T3C-95-128 (C95-02.OUlC9543.04CI7). The principle heat sensitiviv for this materid is rhe exother& reaction which is activated when the temperature exceeds about 25OoC. The breakdown of ferrocyanide to ammonia and formate under strongly basic conditions may begin at temperatures less than IOO' C, but the rate increased strongly with increasing temperature and appeared to be cpmpleted in the time of our tests. Differential thermal analysis @TA) results on feed s1,urry witfiout and with ferrocyrn.de showed only endothermic behavior. This is consistent wiih the dry out and low temperature calcine studies which 'did not indicate any exothermic behavior for the feed slurry with and without ferrocyanide. Feed sIurry cont&ning sugar equal in weight to the nitrate plus nitrite conteat (20% of the total oxides per liter POL)), displayed a distinctly kothennic activity witb light' and smoke production.Physical property observations include the following: The feed slurry coats both glass and stainl'ess steel in the liquid state. The material spalls and falls off as it dries leaving a thin, more adherent, film bebind. Tbe only phase separation observed during these tests occurred as a result of the water condensate Ieaching from the slurry boil spatter. Salt containing condensate re-evaporated as it ran down the side of &e reaction vessel leaving a ring of separated white salts on the vessel wall. The sugar containing slurry simulznt exhibited a volume expansion as a result of the exothermic reaction between sugar and njtrate and nitrite. A yellow salt separated from the glass melt made during the quartz crucible test which looks like salts observed to separate from other HLW simulant melts @CAW based) and identified as sodium sulfate with a small amount of potassium chromate..