Speciation, Dissolution, and Redox Reactions of Chromium Relevant to Pretreatment and Separation of High-Level Tank Wastes

Rai, Dhanpat ; Rao, Linfeng ; Clark, Sue B.

Pacific Northwest National Lab., Richland, WA

关键词: Leaching;    Sludges;    Oxidizers;    Hydroxides;    Redox Reactions;   

DOI  :  10.2172/834814
RP-ID  :  EMSP-81896-2003
RP-ID  :  FG07-01ER14930
RP-ID  :  834814

美国|英语

来源: UNT Digital Library

【 摘 要 】

Chromium, one of the problematic elements in tank sludges, is considered the most important constituent in defining the total volume of high-level waste (HLW) glass. This proposed research seeks to develop fundamental data for Cr reactions that are not currently available but are essential for developing pretreatment processes for removing Cr from HLW sludges. Our objectives are to study (1) the dissolution of several solid phases (e.g., CrOOH, Cr2O3(c), and (Fe,Cr) binary hydroxides, identified to be important from sludge leaching studies) in highly alkaline solutions and in the presence of other electrolytes (e.g., carbonate, phosphate, sulfate, nitrite), and (2) the effect of the nature of Cr solid phases and aqueous species on their redox reactivity with a variety of potential oxidants (e.g., O2 and ferrate). This information will provide critical support for developing enhanced pretreatment strategies for removing Cr from HLW and will achieve a major cost reduction in HLW disposal.