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Title: Process for treating alkaline wastes for vitrification

According to its major aspects and broadly stated, the present invention is a process for treating alkaline waste materials, including high level radioactive wastes, for vitrification. The process involves adjusting the pH of the wastes with nitric acid, adding formic acid (or a process stream containing formic acid) to reduce mercury compounds to elemental mercury and MnO{sub 2} to the Mn(II) ion, and mixing with class formers to produce a melter feed. The process minimizes production of hydrogen due to noble metal-catalyzed formic acid decomposition during, treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product. An important feature of the present invention is the use of different acidifying and reducing, agents to treat the wastes. The nitric acid acidifies the wastes to improve yield stress and supplies acid for various reactions; then the formic acid reduces mercury compounds to elemental mercury and MnO{sub 2}) to the Mn(II) ion. When the pH of the waste is lower, reduction of mercury compounds and MnO{sub 2}) is faster and less formic acid is needed, and the production of hydrogen caused by catalytically-active noble metals is decreased.
Inventors:
Issue Date:
OSTI Identifier:
207561
Assignee:
Dept. of Energy SRS; SCA: 052001; PA: EDB-96:063504; NTS-96:012271; SN: 96001550309
Patent Number(s):
PATENTS-US-A8202619
Application Number:
ON: DE96006515; PAN: 8-202,619; TRN: 96:009338
Contract Number:
AC09-89SR18035
Resource Relation:
Other Information: PBD: 1994
Research Org:
Westinghouse Savannah River Co., Aiken, SC (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; HIGH-LEVEL RADIOACTIVE WASTES; VITRIFICATION; INVENTIONS; RADIOCHEMICAL ANALYSIS; RADIOACTIVE WASTE PROCESSING; GLASS; CERAMIC MELTERS; ALKALINE EARTH ISOTOPES; REDUCING AGENTS; ACIDIFICATION