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Title: Process for treating alkaline wastes for vitrification

A process is described for treating alkaline wastes for vitrification. The process involves acidifying the wastes with an oxidizing agent such as nitric acid, then adding formic acid as a reducing agent, and then mixing with glass formers to produce a melter feed. The nitric acid contributes nitrates that act as an oxidant to balance the redox of the melter feed, prevent reduction of certain species to produce conducting metals, and lower the pH of the wastes to a suitable level for melter operation. The formic acid reduces mercury compounds to elemental mercury for removal by steam stripping, and MnO{sub 2} to the Mn(II) ion to prevent foaming of the glass melt. The optimum amounts of nitric acid and formic acid are determined in relation to the composition of the wastes, including the concentrations of mercury (II) and MnO{sub 2}, noble metal compounds, nitrates, formates and so forth. The process minimizes the amount of hydrogen generated during treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product. 4 figs.
Inventors:
Issue Date:
OSTI Identifier:
87739
Assignee:
Dept. of Energy, Washington, DC (United States) PTO; SCA: 052001; PA: EDB-95:115973; SN: 95001431581
Patent Number(s):
US 5,435,942/A/
Application Number:
PAN: 8-202,619
Contract Number:
AC09-89SR18035
Resource Relation:
Other Information: PBD: 25 Jul 1995
Research Org:
Westinghouse Savannah River Co
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; HAZARDOUS MATERIALS; VITRIFICATION; REDUCTION; RADIOACTIVE WASTE PROCESSING; PH VALUE; PROCESS CONTROL; MANGANESE OXIDES; WASTE FORMS