United States
                                  Environmental Protection
                                  Agency
EPA/540/S-97/501
August 1997
&EPA
                                SUPERFUND INNOVATIVE
                                TECHNOLOGY EVALUATION
                                   Emerging Technology  Summary

                                   Vitrification of Soils Contaminated by
                                   Hazardous and/or  Radioactive  Wastes
                                     A performance summary of  an  ad-
                                   vanced  multifuel-capable combustion
                                   and melting system (CMS) for the vitri-
                                   fication  of hazardous wastes  is pre-
                                   sented.  Vortec  Corporation  has
                                   evaluated its patented CMS for use in
                                   the remediation of soils contaminated
                                   with heavy metals and  radionuclides
                                   under the EPA's SITE  program and
                                   other waste treatment technology evalu-
                                   ation programs. The Vortec CMS has
                                   successfully demonstrated the ability
                                   to effectively treat hazardous and/or ra-
                                   dioactive soils and produce a stable
                                   vitrified  product with excellent leach
                                   resistance. The ability to process con-
                                   taminated soils either as dry granular
                                   solids or in the form of a slurry has
                                   been  demonstrated with  a ORE  of
                                   greater than 99.99% for organic com-
                                   pounds. All the glass produced passed
                                   the TCLP test with the concentration of
                                   contaminants  in the leachates  signifi-
                                   cantly reduced from those of the corre-
                                   sponding feedstocks which did not
                                   pass TCLP. The vitrified product also
                                   demonstrated  superior radionuclide
                                   leach resistance, as no detectable quan-
                                   tities of the surrogate radionuclide were
                                   found by an ANSI/ANS-16.1 test.
                                     This Summary was developed by the
                                   National Risk Management Research
                                   Laboratory's Sustainable  Technology
                                   Division, Cincinnati, OH, to announce
                                   key findings of the SITE Emerging Tech-
                                   nology  program that is fully docu-
                                   mented in a separate report (see Project
                                   Report ordering information at back).

                                   Introduction
                                     Vortec Corporation has developed  an
                                   advanced multifuel-capable  combustion
                                   and melting system (CMS) for the vitrifica-
                                   tion of hazardous wastes.  Vortec has
                                   evaluated the CMS for the remediation of
                                   soils contaminated with heavy metals un-
 der the EPA's SITE Programs, and for the
 remediation of  soils contaminated  with
 heavy metals, organic compounds,  and
 radionuclides under other waste treatment
 technology evaluation programs.
  The soil remediation programs focused
 on demonstrating the ability of the Vortec
 CMS to immobilize heavy metals and ra-
 dionuclides by  incorporating these con-
 taminants into the matrix of a glass—the
 vitrified product. The glass is formed by
 the vitrification of the soil which contains
 the hazardous  constituents.  Depending
 upon the composition of the contaminated
 soil, the addition of inexpensive glass-forming
 agents may be required. The Vortec CMS
 produces a vitrified  product which  has
 long-term stability, reduces the teachabil-
 ity of the heavy metals (and radionuclides)
 below regulatory limits, and results  in  a
 volume reduction of the waste material. In
 the vitrification of contaminated soils  that
 are hazardous  by characteristic and do
 not contain radionuclides, the vitrified prod
 uct would no longer be classified as  a
 hazardous waste.  The Vortec CMS  also
 completely oxidizes any organic compo-
 nents (hazardous  or not)  in the  waste.
 The Vortec CMS has demonstrated a de-
 struction removal efficiency (ORE) greater
 than 99.99% for all organic compounds in
 the soil.
  The unique features of the CMS make
 it particularly suitable for the  rapid  and
 efficient heating of fine granular materials,
 and subsequent vitrification into a glass
 product. A process diagram of the Vortec
 CMS-based soil vitrification system is
 shown in Figure I.
  The basic components of the system
 include:
  • the Vortec multifuel-capable CMS,
    consisting of a counter-rotating vortex
    combustor and a cyclone melter;
  • an upstream storage and feeding sub-
    system;
  • a separator/reservoir assembly;
                                                     AWBERG LIBRARY  U.S.

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                                                                 DATE DUE
                               Fuel Oil
                              or Water
                                      Wet
                                     Grinding
                   Crusher —
                   Dryer/
                   Grinder
                   Dry Soil
                     Bin

                Transport
                   Air
                                              Gla
                                       Agitator
                                        Tank
Glass-Forming
  Additives
 Figure 1.  Vortec's CMS-based contaminated soil vitrificatic
                                                                                                 -r"
                                                                                                        Stack
                                                                                                          ID
                                                                                                         Fan
                                                                                                   Recycled to
                                                                                                  CMS System
                                                                                                   Vitrified
                                                                                                   Product
                                                                                                   Storage
                                                             The Library Store    #47-0106
   •  a cullet handling subsystem;
   •  a heat recoverysubsystem;
   •  a flue gas conditioning assembly; and
   •  an air pollution control subsystem.
   Except for the CMS and the separator/
 reservoir, all other subsystems or assem-
 blies are commercially available or modi-
 fied versions of commercially available
 equipment.
   The basic CMS can be modified to ac-
 commodate the use of a variety of fuels,
 including  pulverized coal, coal slurry fu-
 els, natural gas, oil, waste oils, and waste
 solvents. The CMS is also capable of us-
 ing any combination of these fuels. Natu-
 ral  gas  is  customarily   used   in
 demonstration testing  because of its con-
 venience.
   Complete combustion and in-flight sus-
 pension preheating of the contaminated
 soils, and any  glass-forming  additives,
 takes place in the combustor. The feed-
 stock ingredients are  introduced into the
 combustor through an  injector and are
 rapidly  heated  in  the flame zone.  Any
 carbon-based materials are rapidly volatil-
 ized and oxidized. The inert materials are
 heated  to  nominally  230OF to 280OF,
 depending on the characteristics  of the
 soil, prior  to entering  the cyclone melter.
 Since combustion air is preheated to nomi-
 nally 100OF to 140OF, high local flame
temperatures of more than 400OF can be
achieved in the combustor. However, due
           to the rapid temperature quenching of the
           combustion products by the inert soil par-
           ticles and the staged combustion inherent
           in the  CMS design, the NOx emissions
           have been demonstrated in pilot scale test-
           ing to be lower than DOE's boiler emis-
           sions standard of 0.6 Ibs NOx/MMBtu. NOx
           emissions lower than 2 Ibs NOx/ton glass
           have also been demonstrated.
             The preheated solid materials from the
           combustor enter the cyclone melter, where
           they are  distributed to the chamber walls
           by the cyclone action of the combustion
           products, thus forming  a molten  layer of
           vitrified soil (glass). The glass and the
           combustion products  exit the  cyclone
           melter through a tangential exit  channel
           and  enter  the  separator/reservoir.  The
           separator/reservoir separates the combus-
           tion products from  the  molten glass and
           provides additional  residence time for the
           completion of glass-forming reactions. The
           glass exits the separator/reservoir through
           either a tap hole in the floor or an over-
           flow weir  along a side wall. The combus-
           tion products exit through an exhaust port,
           which discharges   into  a conventional
           radiation-type recuperator for combustion
           air preheating.
             A flue  gas conditioning assembly re-
           duces the  temperature  of the flue gas
           exiting the radiation  recuperator to satisfy
           the temperature requirements of  particu-
           late control devices. Commercially avail-
 able paniculate control devices are incor-
 porated into the  design  as dictated  by
 local environmental regulations. A high ef-
 ficiency venturi scrubber can be used  for
 particulate control in some applications.
 Wet  or dry electrostatic  precipitators
 (ESPs) or baghouses  can be used  to
 achieve higher levels of particulate emis-
 sions control. Additional air pollution con-
 trol, such as acid gas scrubbers, may  be
 easily incorporated if required.
   Two  different techniques for transport-
 ing the contaminated soil into the CMS
 have been investigated. In one feed sys-
 tem, the soil was pneumatically fed to the
 CMS as  dry  granular solids.  However,
 many soils found  at  contaminated sites
 are not  in this preferred (dry) form. There-
 fore, a  second feed system was  devel-
 oped to handle wet soils in the form of a
 slurry. The slurry feed system  provides a
 means  of mixing  the wet contaminated
 soil and a liquid (water), and then deliver-
 ing and  atomizing this slurry into the CMS.
 By processing wet soils in a slurry form,
the preparation and blending of the wet
soil and the  glass-forming materials, as
well as  the introduction of the  resulting
mixture  into the CMS, are simplified. The
Vortec CMS process demonstrated its abil-
ity to process both the dry and slurried
feed materials, while forming a fully-reacted
vitrified product.

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Procedure
  Laboratory melts were conducted  by
Vortec on  EPA's  Synthetic  Soil Matrix
(SSM) to determine whether the addition
of glass-forming agents is required to pro-
duce  a vitrified product that  will consis-
tently pass  the  Toxic Characteristic
Leaching Procedure (TCLP). Table 1 pre-
sents the composition of EPA's SSM and
the resulting feedstock formulation  used
in Vortec's  SITE testing. Vortec, in coop-
eration  with DuPont  Chemicals, estab-
lished the types and quantities of heavy
metal compounds (shown later in Table 2)
that were used to produce the contami-
nated surrogate soil.  Blending  of the sur-
rogate soil,  limestone and the heavy metal
compounds was performed  just prior to
the initiation of testing, thus  minimizing
the possibility of further contamination in
the feedstock.
  The Vortec SITE program has  con-
ducted two  tests at Vortec's nominal 15-20
tons per day pilot facility using surrogate
soil spiked  with heavy metal compounds.
The first test employed the pneumatic feed
system  to  process dry feedstock,  while
the second test used the slurry feed sys-
tem to process an aqueous slurry contain-
ing  contaminated surrogate soil. Prior to
the slurry feed test, an initial combustion
stability test was  successfully  completed
and demonstrated  the ability of the  com-
bustor to accept the designated water flow
rate of 400 pounds per hour. Additional
combustion stability testing was performed
using a slurry of 60% cullet (ground waste
glass) and 40% water. Cullet was used as
the sole constituent, rather than clean soil,
to avoid contamination  of the materials
being used in concurrent testing. The sta-
bility testing using the cullet/water slurry
was also successful and verified the slurry
system design parameters. Finally, a slurry
containing  60%  contaminated surrogate
soil/limestone mixture and 40% water was
used  to perform the second  of Vortec's
contaminated soil  SITE tests. Sampling
and chemical analyses of the influent and
effluent streams from both pilot scale con-
taminated soil tests  were performed  by
DuPont's Water Quality Laboratory, Cham-
bers Works, NJ; and  Geraghty and Miller,
Inc., Pittsburgh, PA.  Under other demon-
stration programs, the  feedstocks  con-
sisted  of  different SSMs, glass-forming
additives, surrogate  heavy  metal com-
pounds, organic compounds, and surro-
gate radionuclides.

Results and Discussion
  The  tests  conducted under the  EPA
SITE Program, as well  as all tests per-
formed  under other  demonstration  pro-
grams,  have satisfied  all  technical and
data quality objectives. Table 2  presents
the metal concentrations in the feedstocks
and the vitrified products produced during
the Vortec SITE tests. Table 2  also  in-
cludes  the results of  the TCLP tests per-
formed on the feedstocks and the vitrified
products.  Due to the high  cadmium  con-
tent in the dry feedstock leachate and the
high cadmium and  lead content in the
slurried feedstock leachate,  both feed-
stocks  failed  TCLP  testing. Therefore,
these feedstocks would be considered haz-
ardous  if classified  as  waste products.
However, all of the glass produced during
Vortec's testing passed TCLP testing, with
the concentration of  heavy metals in the
leachates significantly reduced from those
of the corresponding feedstocks. The  el-
evated chromium content  in  the vitrified
products is due to the leaching of this
element from the refractory present in the
CMS during the SITE testing. Under other
demonstration programs, the vitrified prod-
uct was also evaluated  by the ANSI/
ANS-16.1  test for the leachability of the
surrogate  radionuclide.
  No detectable quantities of the surro-
gate radionuclide were found  in any of the
leachates  collected  during  the ANSI/
ANS-16.1  test procedures.
  Table 3 presents system  mass balances
and emission data for the Vortec SITE
tests. The  production of carbon  dioxide,
Table 1.  EPA's Synthetic Soil Matrix (SSM) and the Feedstock Compositions used during Vortec's
SITE Program
SSM
Si02
A1203
K20
Na20
CaO
Fe203
MgO
Other oxides
Composition
wt%
57.43
11.74
1.55
0.84
20.26
2.32
5.29
0.57
Feedstock
SSM
Limestone
Water
Dry feed test
wt%
80.0
20.0
0.0
Slurry feed test
wt%
48.0
12.0
40.0

water vapor and the volatilization of other
materials present in the feedstock resulted
in the loss  on ignition displayed  in the
table.  Both  uncontrolled and controlled
stack particulate loadings are presented.
During the SITE testing, a venturi  scrub-
ber was used  as the pollution control de-
vice in the CMS exhaust system.  A wet
ESP has  since  been placed in the sys-
tem, and based  on subsequent testing of
a variety of materials, the anticipated emis-
sions under the conditions  that existed
during the SITE tests would be lower than
0.003 gr/dscf.
  As the contaminated soils are processed
within the CMS, the metal contaminants
partition to either the carryover stream or
the glass stream. The volatility of the met-
als and their oxides  is the primary factor
controlling the partitioning of these con-
taminants. The non-volatile metals, chro-
mium, copper,  and  nickel, are  found
primarily in the vitrified product,  while the
semi-volatile metals, cadmium and lead,
have a significantly higher percentage par-
titioning to the  carryover. Table 4 summa-
rizes  the partitioning of  the  metal
contaminants among  all  the  effluent
streams from  the Vortec CMS. Through
the use of  a  high  efficiency particulate
removal system, such as an  ESP (wet or
dry) or a baghouse, the carryover can be
effectively recycled back into the molten
vitrified product  within  the CMS using  a
proprietary  technology developed by
Vortec.  With the implementation  of  this
particulate-carryover  recycle  technology,
the Vortec CMS has the potential  to be-
come a zero  waste discharge  process.
While  the recycling  of  the particulate
carry-over into the  vitrified  product was
not performed  during Vortec's SITE test-
ing, other  programs are currently demon-
strating this carryover recycle feature.

Conclusions and
Recommendations
  Pilot scale vitrification testing has dem-
onstrated that, with the addition  of appro-
priate glass-forming  additives, surrogate
soils representative of EPA Superfund and
other hazardous  waste  sites can be effec-
tively vitrified by the  Vortec CMS. A high
capture rate of the heavy metal contami-
nants into the glass product is achievable
with the  glass consistently  passing the
TCLP testing requirements for the  leach-
ing of RCRA metals. The CMS has dem-
onstrated  DREs  greater than 99.99% for
organic compounds.  In addition, the CMS
has demonstrated the ability  to effectively
process surrogate soil in both wet and dry
forms.  With  the  implementation  of  a pro-
prietary particulate recycling  technology,
the Vortec CMS-based contaminated soil
vitrification system can become a zero
waste discharge  process.

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Table 2.  Summary of Contaminant Concentrations and TCLP Data for the Feedstocks used and the Vitrified Products Collected under Vortec's SITE
 'rogram
Metal
Contaminants
Concentration
 in Feedstock
 Feedstock
TCLP Result
Concentration
   in Glass
   Glass
TCLP Result
   TCLP
RCRA Limit
Dry Feed Test
    PPMa
                                                     PPM"
                           PPMC
                                                                                PPM"
                                                                                                      PPM
Arsenic
Cadmium
Chromium
Copper
Lead
Nickel
Zinc
Slurry Feed Test
(dry basis)
Arsenic
Cadmium
Chromium**
Copper
Lead
Nickel
Zinc
273
187
867
395
2132
128
2395

PPM
112
116
546
235
1106
85
1300
0.97
1.55
0.02
0.06
0.10
1.73
8.71

PPM
1.1
2.7
0.04
3.7
7.5
3.5
26.3
259
75
1615
366
872
189
1615

PPM
275
27
1209
381
505
229
1506
0.00
0.00
0.04
0.04
0.00
0.00
0.12

PPM
0.0
0.008
0.19
0.15
0.13
0.15
0.83
5.
1.0
5.0
N/
5.0
N/
N/

PPM
5.0
1.
5.0
N/A
5.0
N/A
N/A
a Average of 13 samples.
b Average of 19 samples.
c Average of 11 samples.
d Average of 18 samples.
N/A - not applicable.
** Excess levels of chromium leached from refractory into glass.
Table 3.  CMS Performance During Vortec's SITE Program Testing

Mass                                                Dry feed test
                                                  Slurry feed test
Feedstock

Glass produced

Loss on ignition
         Ibs/hr

         Ibs/hr

         Ibs/hr
      947

      721

      195
    450

    212

    235
Emissions data
Uncontrolled particulate

Controlled particulate using
 venturi scrubber

Controlled particulate
 estimate using wet ESP
     % of Feedstock

     % of Feedstock


       grains/dscf
        3.3

        0.3


       <0.003
       0.06

       0.01


     <0.001
Table 4.  Partitioning of Heavy Metals among the CMS Effluent Streams During Vortec's SITE Program

                                  Dry feed test
                                                                            Slurry feed test
Metal
Arsenic
Cadmium
Chromium
Copper
ead
.'Jickel
Zinc
Glass
69.9
50.9
89.4
85.4
44.7
87.5
78.0
Scrubber
27.3
24.6
9.8
12.5
31.6
12.2
16.6
Stack gas
2.8
24.5
0.8
2.1
23.7
0.3
5.4
Glass
91.0
41.2
85.5
96.0
52.7
98.5
92.7
Scrubber
5.4
16.3
11.4
2.2
23.5
0.0
3.7
Stack gas
3.6
42.5
3.1
1.8
23.8
1.5
3.6

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  James G. Hnat Is with Vortec Corporation, Collegeville, PA 19426.
  Ten Richardson is the EPA Project Officer (see below).
  Details of the completed SITE Emerging Technology project are given in an article
    published in Glass Production Technology International, 1994 pp. 103-106.
  The EPA Project Officer can be contacted at:
          Sustainable Technology Division
          National Risk Managemet Research Laboratory
          U.S. Environmental Protection Agency
          Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information (G-72)
Cincinnati, OH 45268


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