United States
Environmental Protection
Agency
EPA/540/F-95/503
March 1995
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Emerging Technology Bulletin
Waste Vitrification Through Electric Melting
Ferro Corporation
Technology Description: The objective of vitrification tech-
nology is to convert contaminated soils, sludges, and sediments
into an oxide glass, rendering them suitable for landfilling as a
nonhazardous material. The technology uses joule heating to
melt the waste matrix, destroying organic compounds in the
process, and encapsulating the inorganic constituents in a leach
resistant form.
Figure 1 shows a schematic of the process. An oxide glass
mixture is mixed with the soil in ratios determined in part by the
contaminants to be vitrified. The glass mixture acts as a fixation
medium and facilitates the flow of current between the electrodes
until the soil reaches a temperature and viscosity sufficient to
conduct the current and produce melting. As the thermal gradient
approaches organic materials, these materials vaporize. The cold
layer of feed at the top of the melter acts as a counterflow
scrubber condensing volatiles and keeping them in the melting
process. Combustion products escaping the melt are processed
in an off-gas collection system.
Waste Applicability: Vitrification stabilizes inorganic compo-
nents found in hazardous waste. The high temperature involved
in glass production (about 1500*C) decomposes anthracene,
bis(2-ethylhexyl phthalate) and pentachlorophenol in waste. The
decomposition products can easily be removed from the low
volume of melter off-gas. The technology can be applied to soil,
sludges, and sediments.
Test Results: Several glass compositions were developed for
vitrification of soils contaminated with organic and inorganic com-
ponents. Ten replicates of the glass were processed from EPA
synthetic soil matrix (SSM) and glass making materials, and
subject to Toxicity Characteristic Leaching Procedure (TCLP)
testing. SSM and glass making additives were processed in a
laboratory-scale unit at temperatures of 1500-2000'C. Materials
were processed at the rate of 17 Ib/hr. The laboratory melter was
operated in a variety of electrode configurations with an energy
usage of 3.3 to 3.5 kilowatt hours per kilogram of material
processed. The feed was composed of 67% soil and 33% glass
making additives. During these tests, measurements were taken
to monitor the process and assess the quality of the vitrified
product. The results of the TCLP Analyses for these replicates
are presented in Table 1.
The results of this study show that the Ferro Corporation waste
vitrification technology was able to:
1) utilize glass compositions tailored to the waste being treated
to vitrify hazardous soils and sludges,
2) produce a vitrified product that can pass TCLP requirements
for the release of seven toxic, inorganic components,
3) continuously produce the target glass composition from an
input of typical soils contaminated with organic and inorganic
species, plus glass making materials.
Glass-making
materials
Electrode
Steel
Frit, marbles, etc.
Stable glass
III II
Disposal
Figure 1. Electric furnace vitrification.
Printed on Recycled Paper
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Table 1. rap Analyses Results For Further Information Contact:
. Randy A. Parker
_ TLCPAnalyte Concentration, ppm __ y s EPA Rjs,< Reduction Engineering Laboratory
Metal Remediation Limit Mean of Glass Replicates
s 5 oo (513) 569-7271 (Fax: 569-7620)
Cd 1 <0.010
Cr 5 0.019
Cu 5 0.355
Pb 5 0. 130
Ni 5 <0.010
Zn 5 0.293
BULK RATE
POSTAGE & FEES PAID
United States
Environmental Protection Agency
Center for Environmental Research Information DCDHIT w
._. . ,.,-ยป,, Af.^^n rtnMI I INO.
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
EPA/540/F-95/503
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