초록 ▼

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 vitrify

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.

대표청구항 ▼

A method for in situ vitrification of soil, comprising: forming an electrode by inserting an electrically conductive shaft within an electrically conductive collar formed of a material and having a diameter for providing a higher degree of thermal conduction than said shaft, positioning said electro

A method for in situ vitrification of soil, comprising: forming an electrode by inserting an electrically conductive shaft within an electrically conductive collar formed of a material and having a diameter for providing a higher degree of thermal conduction than said shaft, positioning said electrode in the soil at a location spaced from a second electrode such that a lower portion of the first mentioned electrode is embedded in the soil while an upper portion extends above the soil level, passing an electric current between said electrodes and through the soil therebetween for raising the temperature of the soil and melting said soil at levels along and between said electrodes including conducting heat to the top level of melted soil via said collar in an enhanced manner by virtue of its higher thermal conduction as compared with that of the shaft alone to inhibit formation of cold cap material, and discontinuing the flow of current to permit cooling and solidification of said soil between said electrodes.