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Title: Cold cap subsidence for in situ vitrification and electrodes therefor

Abstract

An electrode for use in in situ vitrification of soil comprises a molybdenum rod received within a conductive sleeve or collar formed of graphite. Electrodes of this type are placed on either side of a region containing buried waste material and an electric current is passed therebetween for vitrifying the soil between the electrodes. The graphite collar enhances the thermal conductivity of the electrode, bringing heat to the surface, and preventing the formation of a cold cap of material above the ground surface. The annulus between the molybdenum rod electrode and the graphite collar is filled with a conductive ceramic powder of a type that sinters upon the molybdenum rod, protecting the same from oxidation as the graphite material is consumed, or a metal powder which liquifies at operating temperatures. The molybdenum rod in the former case may be coated with an oxidation protectant, e.g. of molybdenum disilicide. As insulative blanket is suitably placed on the surface of the soil during processing to promote subsidence by allowing off-gassing and reducing surface heat loss. In other embodiments, connection to vitrification electrodes is provided below ground level to avoid loss of connection due to electrodes deterioration, or a sacrificial electrode may bemore » employed when operation is started. Outboard electrodes can be utilized to square up the vitrified area. Further, the center of the molybdenum rod can be made hollow and filled with a powdered metal, such as copper, which liquifies at operating temperatures. In one embodiment, the molybdenum rod and the graphite collar are physically joined at the bottom.« less

Inventors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. (Richland, WA)
Issue Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA
OSTI Identifier:
868214
Patent Number(s):
5100259
Assignee:
Battelle Memorial Institute (Richland, WA) PNNL
DOE Contract Number:  
AC06-76RL01830
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
cold; cap; subsidence; situ; vitrification; electrodes; electrode; soil; comprises; molybdenum; rod; received; conductive; sleeve; collar; formed; graphite; type; placed; region; containing; buried; waste; material; electric; current; passed; therebetween; vitrifying; enhances; thermal; conductivity; bringing; heat; surface; preventing; formation; ground; annulus; filled; ceramic; powder; sinters; protecting; oxidation; consumed; metal; liquifies; operating; temperatures; former; coated; protectant; disilicide; insulative; blanket; suitably; processing; promote; allowing; off-gassing; reducing; loss; embodiments; connection; provided; below; level; avoid; due; deterioration; sacrificial; employed; operation; started; outboard; utilized; square; vitrified; center; hollow; powdered; copper; embodiment; physically; joined; bottom; region containing; situ vitrification; ground level; graphite collar; heat loss; ceramic powder; buried waste; electric current; thermal conductivity; waste material; operating temperature; operating temperatures; molybdenum disilicide; metal powder; conductive ceramic; powdered metal; ground surface; molybdenum rod; surface heat; physically joined; rod electrode; below ground; cold cap; collar formed; rod received; oil comprises; conductive sleeve; /405/166/219/

Citation Formats

Buelt, James L., Carter, John G., Eschbach, Eugene A., FitzPatrick, Vincent F., Koehmstedt, Paul L., Morgan, William C., Oma, Kenton H., and Timmerman, Craig L. Cold cap subsidence for in situ vitrification and electrodes therefor. United States: N. p., 1992. Web.
Buelt, James L., Carter, John G., Eschbach, Eugene A., FitzPatrick, Vincent F., Koehmstedt, Paul L., Morgan, William C., Oma, Kenton H., & Timmerman, Craig L. Cold cap subsidence for in situ vitrification and electrodes therefor. United States.
Buelt, James L., Carter, John G., Eschbach, Eugene A., FitzPatrick, Vincent F., Koehmstedt, Paul L., Morgan, William C., Oma, Kenton H., and Timmerman, Craig L. Wed . "Cold cap subsidence for in situ vitrification and electrodes therefor". United States. https://www.osti.gov/servlets/purl/868214.
@article{osti_868214,
title = {Cold cap subsidence for in situ vitrification and electrodes therefor},
author = {Buelt, James L. and Carter, John G. and Eschbach, Eugene A. and FitzPatrick, Vincent F. and Koehmstedt, Paul L. and Morgan, William C. and Oma, Kenton H. and Timmerman, Craig L.},
abstractNote = {An electrode for use in in situ vitrification of soil comprises a molybdenum rod received within a conductive sleeve or collar formed of graphite. Electrodes of this type are placed on either side of a region containing buried waste material and an electric current is passed therebetween for vitrifying the soil between the electrodes. The graphite collar enhances the thermal conductivity of the electrode, bringing heat to the surface, and preventing the formation of a cold cap of material above the ground surface. The annulus between the molybdenum rod electrode and the graphite collar is filled with a conductive ceramic powder of a type that sinters upon the molybdenum rod, protecting the same from oxidation as the graphite material is consumed, or a metal powder which liquifies at operating temperatures. The molybdenum rod in the former case may be coated with an oxidation protectant, e.g. of molybdenum disilicide. As insulative blanket is suitably placed on the surface of the soil during processing to promote subsidence by allowing off-gassing and reducing surface heat loss. In other embodiments, connection to vitrification electrodes is provided below ground level to avoid loss of connection due to electrodes deterioration, or a sacrificial electrode may be employed when operation is started. Outboard electrodes can be utilized to square up the vitrified area. Further, the center of the molybdenum rod can be made hollow and filled with a powdered metal, such as copper, which liquifies at operating temperatures. In one embodiment, the molybdenum rod and the graphite collar are physically joined at the bottom.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {1}
}

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