In situ vitrification processing of soils contaminated with hazardous wastes
In-situ vitrification (ISV) is a thermal treatment process that converts contaminated soil into a chemically inert and stable glass and crystalline product. Figure 1 illustrates how the process operates. A square array of four electrodes is inserted into the ground to the desired treatment depth. Because the soil is not electrically conductive once the moisture has been driven off, a conductive mixture of flaked graphite and glass frit is placed among the electrodes to act as the starter path. An electrical potential is applied to the electrodes, which establishes an electrical current in the starter path. The resultant power heats the starter path and surrounding soil up to 3600/degree/F (2000/degree/C), well above the initial melting temperature or fusion temperature of soils. The normal fusion temperature of soil ranges between 2000--2500/degree/F (1110--1400/degree/C). The graphite starter path is eventually consumed by oxidation, and the current is transferred to the molten soil, which is now electrically conductive. As the vitrified zone grows, it incorporates nonvolatile elements and destroys organic components by pyrolysis. The pyrolyzed by-products migrate to the surface of the vitrified zone, where they combust in the presence of oxygen. A hood placed over the processing area provides confinement for the combustion gases, and the gases are drawn into the off-gas treatment system. This paper describes the large-scale ISV system, discusses its capabilities, and summarizes the results of testing to date. 11 refs., 10 figs., 2 tabs.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6725606
- Report Number(s):
- PNL-SA-15168; CONF-8709366-1; ON: DE89001480
- Resource Relation:
- Conference: 2. national conference on environmental and public health effects of soils contaminated with petroleum products, Amherst, MA, USA, 28 Sep 1987; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
HAZARDOUS MATERIALS
PYROLYSIS
SOILS
IN-SITU PROCESSING
VITRIFICATION
COST ESTIMATION
EVALUATION
FIELD TESTS
GLASS
CHEMICAL REACTIONS
DECOMPOSITION
MATERIALS
PROCESSING
TESTING
THERMOCHEMICAL PROCESSES
052002* - Nuclear Fuels- Waste Disposal & Storage
053000 - Nuclear Fuels- Environmental Aspects