Vitrification technology

T0088 Battelle Pacific Northwest National Laboratory, Terra-VLT Vitrification Technology T0090 Beco Engineering Company, Alka/Sorb... 

Most of the cost data for vitrification technologies are estimates based on pilot-scale operations. Such data are suspect because they are based more on extrapolation than on experience. Such estimates are difficult to compare because the assumptions on which they are based may vary widely (D18248T, p. 55). 

Many site-specific characteristics have an impact on vitrification technologies. One critical aspect of any thermal technology is the water content of the waste. Water dilutes feed material, requires energy to drive off, and physically limits the feed rate of waste. Feed preparation is another variable, which differs with the technology and with site-specific characteristics. Many estimates do not take into account site preparation and waste disposal costs. Only complete treatment life-cycle assessments can provide reliable comparison data, and such studies are, by definition, highly site and waste specific (D18248T, p. 55). 

Electro-Pyrolysis, Inc. (EPI) has developed the direct current (DC) graphite arc furnace vitrification technology for the ex situ treatment of wastes. The arc furnace can be operated as an oxidation or reduction process. The vendor states that DC arc melter treatment produces a leach-resistant solid and reduces the volume of wastes that require disposal. 

MeItTran, Inc. (MeItTran), has developed the Ultimate Solution, an ex situ vitrification technology that uses a direct current (DC) arc system to treat hazardous wastes. The vendor claims that organic materials are destroyed by the technology and that inorganic materials are melted and cooled into a leach-resistant final waste form. RIMS were unable to obtain information from the vendor in regards to performance or commercial availability. 

Allied Technology Group (ATG) hired PEAT, Inc., to build a TDR system to treat mixed waste from the DOE s Hanford facility in Richland, Washington. The PEAT system will treat 250 lb of mixed waste per hour (D186838, p. 1). The total value of the DOE contract is 24 million and the TDR contract is worth 4.3 million. This calculates a treatment cost of approximately 4700/m of waste treated. At the other DOE sites, treatment costs for other vitrification technologies are estimated between 5600 and 6400/m (D186838, p. 1 D18248T, p. 55). 

Many vitrification technologies operate using plasma, an ionized gas to melt wastes. At high temperatures, electrons are stripped of their nuclei and the matter exists as a mixture of negative electrons, positive nuclei, and atoms. The ionized particles allow plasma to be an excellent conductor of heat and electricity. Plasma vitrification technology is commercially available in the United States and internationally. 

Many site-specific characteristics have an impact on vitrification technologies. One critical aspect of any thermal technology is the water content of the waste. Water dilutes feed material. 

The additional energy input needed for waste vitrification technologies, compared to conventional incinerators that even recover residual energy, may be considered detrimental to the net energy balance of the complete path resource — waste . However, this additional energy requirement can also be considered as the additional price to pay for the efficient exploitation of natural resources. To be sustainable, HT materials should fulfil the following requirements ... 

Ewing, R. C. 1996. Glass as a Waste Form and Vitrification Technology Summary of an International Workshop. National Research Council, National Academy Press, Washington. 

Vitrification technologies may be ex situ or in situ. In ex situ vitrification, any soils, sediments, or buried wastes are excavated. After possible pretreatment to reduce arsenic volatilization, the materials are placed in a furnace and melted at temperatures as high as 2000 °C. The heat may be generated by fossil fuels, electricity, plasma torches, or microwaves (US EPA), 2002a, 5.1). 

Vitrification technology for production of waste forms is the most developed and is only presently utilized at an industrial scale. Currently actual HLW from SNF reprocessing is being vitrified with production of borosilicate glass in France and UK using an inductively-heated (200-300 kHz) metallic (Inconel-690) melter [44,45]. Replacement of the induction-heated metallic melter by a cold-crucible melter is being considered [46]. In the USA and Russia Joule-heated ceramic melters are implemented for HLW vitrification in borosilicate or phosphate [24,47-50] glasses. By the end of 2000 the total amount of vitrified radioactive waste in the world was about 10 000 MT [43]. 

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