Selective Leaching of Chromium from Hanford Tank Sludge 241-U-108

Rapko, Brian M. ; Vienna, John D.

Pacific Northwest National Laboratory (U.S.)

关键词: Leaching;    Sludges;    Oxidizers;    Peroxynitrite;    Hydroxides;   

DOI  :  10.2172/860129
RP-ID  :  PNNL-14019
RP-ID  :  AC05-76RL01830
RP-ID  :  860129

美国|英语

来源: UNT Digital Library

【 摘 要 】

This study evaluated the oxidants permanganate, MnO4-, and peroxynitrite, ONOO-, as selective chromium-leaching agents from washed 241-U-108 tank sludge under varying conditions of hydroxide concentration, temperature, and time. The mass changes and final sludge compositions were evaluated using glass-property models to ascertain the relative impacts of the various oxidative alkaline leach conditions on the amount of borosilicate glass required to immobilize a given amount of washed 241-U-108 Hanford tank sludge. Only permanganate leaching removes sufficient chromium to make the chromium concentration in the oxidatively alkaline leached solids non-limiting. In the absence of added oxidants, continued washing or caustic leaching have no beneficial effects. Peroxynitrite addition reduces the amount of glass required to immobilize a given amount of washed 241-U-108 tank sludge by approximately a factor of two. Depending on the leach conditions and the exact chromium concentration limits, contact with alkaline permanganate solutions reduces the amount of immobilized high-level waste glass by a factor of 10 to 30.