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Thermochemical processing using powder metalfuels of radioactive and hazardous waste
M I Ojovan1�, W E Lee1, I A Sobolev2, S A Dmitriev2, O K Karlina2, V L Klimov2, G A Petrov2
and C N Semenov2
1Immobilization Science Laboratory, Department of Engineering Materials, University of Sheffield, Sheffield, UK2Moscow SIA ‘Radon’, Moscow, Russia
Abstract: An overview of thermochemical treatment technologies (TTTs) for radioactive and toxic wastes
is given. TTTs have been developed for pretreatment (e.g. decontamination), treatment and conditioning of
specific wastes such as mixed, organic or chlorine-containing radioactive waste and contaminated soils.
TTTs use powder metal fuels (PMFs) specifically formulated for the waste composition, which react with
some of the waste components. Thermochemical processing can be carried out in a self-sustaining
regime and enables ecologically safe processing of wastes without complex and expensive equipment. It
leads to almost total confinement of contaminants in a mineral or glass composite end-product with minimal
release of hazardous components and radionuclides in the off-gas.
Keywords: thermochemical processes, waste processing, radioactive waste, toxic waste
NOTATION
IER ion-exchange resin
PMF powder metal fuel
PVC polyvinyl chloride
SHS self-sustaining high-temperature synthesis
SIA Scientific and Industrial Association
TTT thermochemical treatment technology
VRC volume reduction factor
1 INTRODUCTION
Thermochemical processing has been developed predomi-
nantly in Russia to immobilize toxic and radioactive
wastes and utilizes selective combustion of powder metal
fuel (PMF) constituents with the most hazardous waste
components in a heterogeneous system ensuring complete
decomposition of organics and retention of toxic and radio-
active elements in the condensed combustion products.
These are in the form of mineral-like or glass composite
materials suitable for subsequent safe storage, transpor-
tation and eventual reuse of non-radioactive materials or
disposal of radioactive waste.
Thermochemical treatment technologies (TTTs) are
intended for pretreatment (e.g. decontamination), treatment
and conditioning of specific types of radioactive and toxic
waste such as spent ion-exchange resins, inorganic absor-
bents, wastes from research nuclear reactors, irradiated
graphite, mixed, organic or chlorine-containing radioactive
waste, contaminated soils and unburnable heavily surface-
contaminated materials. Table 1 compares TTTs with
other thermal methods for processing of wastes.
Thermochemical processing uses the energy of exothermic
reactions in a mixture of radioactive or hazardous waste with
PMF. The PMF composition is designed to minimize the
release of hazardous substances and radionuclides in the
off-gas and to confine the contaminants in the solid products.
Generally, the PMF consists of combustible powder
metals, oxygen-containing components and some additives
(pore-formingmaterials, stabilizers, surface-active substances
and others), with a predominance of metal powders. Thermo-
dynamic simulation is applied widely during designing of the
PMF, followed by experimental performance and operational
safety assessment tests of TTTs.
2 TTT DEVELOPMENT AND APPLICATIONS
A number of applications of thermochemical processing
methods have been demonstrated, including:
(a) pretreatment: surface decontamination of metals,
asphalt and concrete;
The MS was received on 18 November 2003 and was accepted after revisionfor publication on 14 June 2004.�Corresponding author: Department of Engineering Materials, Universityof Sheffield, Sir Robert Hadfield Building, Mappin Street, SheffieldS1 3JD, UK.
1
E04503 # IMechE 2004 Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering
(b) treatment: processing of organic wastes, namely spent
ion-exchange resins, plastics, polymers and medical
and biological waste;
(c) treatment and immobilization: processing irradiated
reactor graphite with almost total 14C retention;
(d) immobilization: self-sustaining vitrification ash resi-
dues, calcined bottom residues, spent inorganic sor-
bents, contaminated soils.
Potential applications of TTTs have also been investigated,
including:
(a) self-sustaining processing of zirconium-containing radio-
active waste with synthesis of Synroc-type waste forms;
(b) self-sustaining immobilization of U- and Pu-containing
wastes in mineral-like and glass composite materials;
(c) remelting and decontamination of metallic wastes, e.g.
stainless steel.
Initial studies ofwaste thermochemical processingwere carried
out at the end of the 1980s andwere intended to study the feasi-
bility of self-sustaining high-temperature synthesis (SHS). A
novel, highly efficient, ecologically safe and cheap calcination
method evolved from this was with SHS being supplied by
PMF components selectively interacting with nitrogen oxides
[1]. This method, however, has not been used on an industrial
scale, since the Russian vitrification processes used a one-stage
calcination–melting approach utilizing non-calcined wastes.
Nonetheless, TTT was developed to produce ceramic waste
forms immobilizing liquid wastes (bottom residues) using a
clay base to absorb toxicants and SHS to sustain sintering of
the ceramics [2]. In the mid-1990s a thermochemical deconta-
mination method was developed to remove radioactive spots
from asphalt coatings [3]. These studies were followed by
development of a new PMF composition enabling decontami-
nation of metals and concrete surfaces [4, 5]. Moreover, the
possibility was demonstrated of removing deep penetrating
contaminants from up to 100 mm depth of stainless steel
using certain PMF [6].
Incineration of biological waste was a tremendous chal-
lenge in the 1990s, particularly with respect to cattle dis-
eases such as spongiform encephalitis, and led to
development of a new PMF able to incinerate large numbers
of animal cadavers in field conditions [7, 8]. Self-sustaining
vitrification was used to immobilize ash residues, contami-
nated clays and spent inorganic sorbents [9]. A TTT process
was invented to combust organic ion exchangers and
immobilize ash residues [10]. Almost full retention of
radioactive contaminants including the most dangerous con-
stituent of irradiated reactor graphite 14C in a corundum–
carbide waste form via a specially designed SHS process
was demonstrated in a number of studies [11].
TTTs were show to be feasible for synthesizing Synroc-
type waste forms [12]. Mineral-like waste forms were pro-
duced via TTTs to retain long-lived radionuclides, e.g. U
and Pu [13], and this process is currently being tailored for
in situ application in borehole repositories [14]. TTTs were
also demonstrated to be useful for remelting metallic wastes
including stainless steel [15]. Table 2 gives a brief overview
of the most important milestones in developing TTT.
Table 1 Comparison of thermal treatment methods
Method ThermolysisSelf-sustaining high-temperaturesynthesis (SHS) Thermochemical processing (TTTs)
Characteristics Thermal processing withdecomposition of chemicalcompounds on heating
Chemical process that occurs withrelease of heat in autowave regimeof combustion and resulting information of solid products
Thermochemical process that useswaste specific fuels and utilizesconstituents in both synthesis anddecomposition chemical reactions.May involve liquid phase
Area of application Toxic, low- and intermediate-levelradioactive wastes, mixed wastes
Toxic, low-, intermediate- and high-level radioactive wastes, mixedwastes
Toxic, low-, intermediate- and high-level radioactive wastes, mixedwastes
Main targets Decomposition of organics, volumereduction
Synthesis of waste forms Decomposition of organics, volumereduction; synthesis of wasteforms; immobilization throughmelting; decontamination;selective recovery
Stage of implementation Industrial application Laboratory experiments Pilot industrial application
Advantages Universal High efficiency High efficiency and selectivity
Table 2 Thermochemical treatment methods for toxic and radio-
active wastes
Method Reference
Calcination of wastes [1]Sintering of ceramics [2]Decontamination of asphalt [3]Decontamination of concrete [4]Decontamination of metals [5]Deep decontamination of metals [6]Treatment of mixed wastes [7]Incineration of biological wastes [8]Vitrification of ash residues [9]Incineration of ion exchangers [10]Processing of reactor graphite [11]Synthesis of Synroc-type ceramics [12]Synthesis of mineral-like matrices [13]Immobilisation of U- and Pu-containing wastes [14]Remelting of metals [15]
2 M I OJOVAN, W E LEE, I A SOBOLEV, S A DMITRIEV, et al.
Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering E04503 # IMechE 2004
3 THERMOCHEMICAL DECONTAMINATION
The thermochemical decontamination technique can be
used to decontaminate surfaces of materials including
asphalt, concrete and metals. This technology is particularly
suitable when the radioactive contamination is strongly
bonded in the near-surface layers where conventional
decontamination methods cannot efficiently remove the
radionuclides [16]. Thermochemical decontamination is
based on thermal treatment of a superficial layer of contami-
nated material by the heat generated from combustion of a
layer of PMF covering the surface (Fig. 1) [3–6].
The PMF layer on the surface is burning flameless and
continuously within a few minutes. The heat volatilizes
most of the radionuclides, which are then trapped by
the resulting slag layer, which is formed as a result of
PMF combustion. Thermochemical interaction between
the slag layer and decontaminated material may also result
in removal of a near-surface layer along with the
contaminants.
Thermochemical decontamination technology is rather
simple and comprises few operations [3–6]. The first oper-
ation is to determine the extent of and then to cover the con-
taminated region of the surface with a thin (0.8–1 cm) layer
of PMF. This layer is then ignited, combustion lasting
for several to a few tens of minutes, depending on the
PMF type. The last stage following the extinction of the
PMF involves collecting the resulting slag from the surface.
Decontamination efficiency is calculated by the formula
K ¼A0 � Af
A0
100% (1)
where A0 is the radioactivity of the material surface before
decontamination and Af is the radioactivity of the material
surface after decontamination. The decontamination effi-
ciency depends mainly on temperature and duration of sur-
face heating. These variables are determined by the PMF
composition and its consumption per unit of treated area.
Process optimization for various materials includes select-
ing the mixture composition and ensuring the necessary
combustion temperature.
Decontamination of metal surfaces is achieved as a result
of radionuclide volatilization and their fixation in a slag
layer that forms as a result of PMF combustion. To
remove well-bonded radioactive contamination typically
requires removal of a thin layer (�1 mm) of the metal sur-
face. Relatively deep penetration of radioactive contami-
nants into metals may occur owing to corrosive and
mechanical destruction of the near-surface metal structure.
A special thermochemical technique has been developed
for deep (�100 m) decontamination, which combines both
thermal volatilization and chemical surface oxidation of
the metal [6, 15–17].
Thermochemical decontamination of concrete (Fig. 2) is
achieved via thermal shock spallation caused by PMF. The
PMF is coated on the contaminated concrete plate and
ignited. After PMF combustion, the concrete upper layers
crack and spall. These spalled concrete fragments are
embedded in the slag and both are removed after cooling.
Decontamination efficiency for concrete is as high as
90–95 per cent for each decontamination procedure.
The depth of radioactive contamination removed is up to
5–8 mm, and these procedures can be repeated if necessary
to remove several layers of contaminated concrete.
Fig. 1 Schematic of a thermochemical decontamination
technique
Fig. 2 Thermochemical decontamination of a concrete slab: PMF layer covers the contaminated region (left)
and spalled fragments ready for collection (right)
THERMOCHEMICAL PROCESSING USING POWDER METAL FUELS OF RADIOACTIVE AND HAZARDOUS WASTE 3
E04503 # IMechE 2004 Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering
For asphalt decontamination transfer, of the contaminated
layer to the softened state of asphalt is achieved at
130–180 8C. The glass fibre backed PMF filling is applied
to the contaminated asphalt surface. After PMF combustion,
the softened asphalt is removed mechanically to the neces-
sary depth. The deeper the radionuclide contamination of
asphalt, the longer is the PMF combustion and consequently
the thicker the PMF layer needed.
The main characteristics of the thermochemical deconta-
mination method are given in Table 3. Thermochemical
decontamination was successfully used in many cases
when conventional methods were inefficient [3–6, 16, 17].
4 PROCESSING OF ORGANIC WASTES
Some organic radioactive wastes require special treatment
technologies. These include spent ion-exchange resins
(IERs), mixed, polymer and chlorine-containing (for
example PVC) wastes and biological objects. The thermo-
chemical processing of radioactive organic waste is based
on application of a specifically formulated PMF. The com-
position of this PMF is designed using thermodynamic cal-
culations and takes into account the chemical composition
of waste and the need to decompose certain organics but
retain the toxic and radioactive elements. The goal of the
thermodynamic simulation is to achieve simultaneous
decomposition of organic matter in the waste and retention
of hazardous radionuclides and chemical species in the final
ash–slag product.
IERs most generally used in water purification systems at
nuclear power stations and nuclear research centres are
copolymers of styrene and divinylbenzene. The thermo-
chemical technology for spent IERs was developed to
treat resins in a wet state [18, 19]. Spent IERs usually con-
tain a large amount of water, often more than 50 wt %. The
major radioactive contaminants of spent IERs are 137Cs,90Sr, 60Co, 106Ru and 54Mn. In addition, spent IERs are fre-
quently contaminated with heavy and toxic metals. The
metal powders in the PMF (including Al, Mg, Ca and Si)
react with water from the IERs, producing enough heat to
sustain its thermal destruction and interaction with the
PMF-generated slag. As a result, the waste volume is
decreased significantly and contaminants combine with
the PMF slag to form chemically stable compounds. A
number of PMFs have been developed for this purpose
(Table 4).
The process of incineration of IERs mixed with PMFs is
illustrated schematically in Fig. 3. A wet IER and PMF,
previously mixed in the appropriate ratio, are fed into the
furnace where reaction is initiated and combustion occurs,
resulting in the release of a great quantity of heat, evapor-
ation and gasification of the IER. Air is supplied to the
combustion chamber to burn out the products of IER gasifi-
cation and hydrogen resulting from the reaction of the metal
with water.
The process in the furnace is controlled so that radio-
nuclides contained in the wet resin are converted into low-
volatile compounds of ash residue. Figure 4 shows an
actual thermochemical facility (capacity up to 20 kg/h).
Table 3 Main features of thermochemical decontamination process
Material
Maximumtemperatureachieved(8C)
Duration ofPMFcombustionprocess(min)
Efficiency ofdecontamination(%)
Radionuclidecarryover(137Cs) (%)
Metal 1100 20 95–99 0.1–0.5Asphalt 400 15 99.9 0.1–0.5Concrete 1300 20 95–99 0.1–0.5
Table 4 Main characteristics of PMFs for the thermochemical
processing of IERs
PMFMajorcombustible
Heatvalue Hu
(kJ/kg)
Stoichiometriccoefficient L0(kg air/kg PMF)
Bulkdensity(kg/m3)
MTKD-45 Mg, Al 27 000 3.35 680–710SKTKD-50 Mg, Ca, Al,
Si26 000 3.46 900–1000
SKTKD-51 Mg, Al, Si 25 900 3.95 800–900
Fig. 3 Schematic of thermochemical treatment of IER: 1, wet
IER; 2, PMF; 3, mixer; 4, mixture; 5, air supply;
6, reactor; 7, off-gases; 8, ash–slag residue
Fig. 4 View of thermochemical reactor for incineration of
spent ion-exchange resins
4 M I OJOVAN, W E LEE, I A SOBOLEV, S A DMITRIEV, et al.
Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering E04503 # IMechE 2004
Thermochemical treatment of organic polymer materials
is performed in much the same way. In the case of chlorine-
bearing polymers, chlorine from the polymer and the metal
in the PMF combine to form chemical compounds, which
are retained in the slag [19].
Table 5 shows the NOx, SOx and CO content in the
gaseous combustion product of a mixture of wet IER
(KU-2-8) and PMF type MTKD-45 at the furnace outlet.
Note that these gases are directed to the gas purification
system before being discharged into the atmosphere so
that the concentrations of these contaminants are further
diminished by several orders of magnitude.
The volume reduction coefficients (VRCs) depend on the
PMF type used. These were 9.5, 10 and 14 in the case of
PMF types SKTKD-50, MTKD-45 and SKTKD-51 respect-
ively. Analysis of the ash residue shows that the slag con-
fines radionuclides in fixed form at levels of 90 per cent
or more for 137Cs and more than 95 per cent for 90Sr and60Co [18, 19].
The problem of neutralization of hazardous biological
objects, for example, cadavers of animals affected by var-
ious virus and bacteriological diseases, is of great current
interest. Conventional burial of such cadavers may generate
sources of epidemics so that incineration has become
accepted as the best method of rendering harmless this
toxic waste. High temperatures above 1000 8C ensure
destruction of organics and guarantee an absence of viruses
in the resulting ash. However, incineration of animal cada-
vers using hydrocarbon fuels requires complicated and
expensive equipment. It consumes large amounts of conven-
tional fuel because of its two-step nature: drying of the
cadaver, and incineration proper of its constituents, e.g.
proteins, fats and bones. In contrast to this, the application
of a PMF permits practically apparatus-free incineration
of large animal cadavers in field conditions (Fig. 5).
The consumption of the PMF is rather small owing to the
use of the water from a biological object in reactions, thus
ensuring a one-step incineration process. Apparatus-free,
highly efficient technology for incineration of animal cada-
vers in field conditions has been demonstrated using PMF,
including an international demonstration in Brno, Czech
Republic [8, 20]. The performance of the method developed
is governed by the active chemical interaction of the PMF
with water of the biological tissue. Figure 6 shows three
photographs taken during the incineration of a cow in
field conditions.
Chemical analysis of aerosols and gases released from the
reaction zone did not show excessive concentrations of
nitrogen, carbon and sulphur oxides. Analysis of ash and
slag showed an absence of hazardous metals, chemical com-
pounds and any organic substances (Table 6).
The remnant ash–slag residue after cadaver/PMF incin-
eration can also be used as a fertilizer. It should be pointed
that this technology can be applied to the incineration of bio-
logical residues of different origins, including vegetation.
Table 5 Chemical contaminants in off-gases from IER combus-
tion by a PMF
Contaminant
Average/maximumcontent in thecombustion products(mg/m3)
Typical maximumpermittedconcentrations [16](mg/m3)
NO and NO2 20/50 300–500SO2 and SO3 220/430 100–2000CO ,1.25 50–200
Fig. 5 Schematic of PMF field incineration of biological
waste: 1, cadaver of animal; 2, trench; 3, fire grate;
4, air supply; 5, vertical supports; 6, metal hood; 7,
layer of PMF with coke
Fig. 6 PMF field incineration of biological waste: left, before; centre, process under way; right, final ash–slag
residue
THERMOCHEMICAL PROCESSING USING POWDER METAL FUELS OF RADIOACTIVE AND HAZARDOUS WASTE 5
E04503 # IMechE 2004 Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering
5 PROCESSING OF IRRADIATED REACTORGRAPHITE
Graphite waste containing fragments of fuel and activation
and fission products mainly arise during operation of
uranium–graphite reactors. The 14C content in reactor
graphite may be as much as 1 wt %. For safe disposal and
long-term storage, such waste must be properly processed
into chemically stable materials. Other carbon-containing
(including 14C radionuclide) wastes are also the subject of
special attention. Incineration of irradiated carbon is not
permitted because of discharge into the atmosphere of bio-
logically significant 14C in 14CO2 and14CO. To treat 14C-
containing waste, a thermochemical treatment technology
has been developed based on self-sustaining exothermic
reactions in a mixture of carbon (graphite), aluminium and
titanium dioxide [11, 21]
3C (graphite)þ 4Alþ 3TiO2 ! 3TiCþ 2Al2O3
As a result, 14C and other radionuclides become immobi-
lized in a stable carbide–corundum ceramic matrix.
Figure 7 demonstrates the SHS process of formation of
carbide–corundum waste from a mixture of graphite
with PMF.
Thermochemical processing of graphite is carried out in
an inert atmosphere, e.g. in an argon atmosphere. A mixture
of PMF with powdered graphite is placed into a crucible
container where the self-sustaining synthesis reaction
is ignited (Fig. 7, left photo). The self-sustaining process
occurs with substantial release of heat; temperatures
higher than 1700 8C are achieved. Nevertheless, the relative
carryover of carbon is minimized to values of 1024/1027 for
CO and CO2 respectively. The self-sustaining reactions
result in a chemically stable titanium carbide–corundum
matrix acceptable for long-term storage and disposal.
Special additions such as zircon, barium and calcium
metatitanites have also been used to improve radionuclide
retention [22–24].
6 SELF-SUSTAINING IMMOBILIZATION
While vitrification is the best current solution for immobi-
lizing hazardous waste, its use is limited to large-volume
waste streams such as high- and intermediate-level nuclear
waste. This is due to the relative complexity of the vitrifica-
tion technology and the high initial cost of equipment. How-
ever, in addition, a range of accumulated wastes of different
composition and properties from the bulk streams have been
generated during various activities of both industrial facili-
ties and research institutions, usually in relatively small
amounts. Examples include spent ion exchangers, wastes
from research centres, contaminated soils and incinerator
ashes. Owing to the relatively small volumes of such
wastes, the use of conventional vitrification technologies
cannot be justified. A viable alternative is the application
of a self-sustaining immobilization process that utilizes
the energy released during exothermic chemical reactions
Table 6 Results of the analysis of ash–slag residue
Parameter
From the results ofLABTECH Brno,Czech Republic(mg/l)
From the resultsof SIA ‘Radon’(wt %)
Sum of polycyclicaromatichydrocarbons
,0.0006 Not measured
Al 195 4Sb ,0.001 Not measuredPb ,0.05 Not measuredCd ,0.005 Not measuredHg ,0.0008 Not measuredFe ,0.1 Not measuredAmmonia ions 175 Not measuredNitrides 0.22 Not measuredPhosphates 0.6 Not measuredSulphates ,0.6 Not measuredK2O Not measured 3MgO Not measured 49Al2O3 Not measured 20MgAl2O3 Not measured 24
Fig. 7 Thermochemical processing of graphite: left, ignition: centre, downward motion of reactive zone;
right, final product
6 M I OJOVAN, W E LEE, I A SOBOLEV, S A DMITRIEV, et al.
Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering E04503 # IMechE 2004
in a mixture of radioactive waste with specially designed
PMFs [9, 25–28]. PMFs are used to melt the waste and
form a glass-like material without requiring an external
power supply. This process is controlled by the composition
of the initial mixture of waste and PMF. The composition of
the PMF is designed to release sufficient heat to sustain
waste melting and to produce a mineral or glass-like end-
product. Suitable PMF compositions and PMF/waste
ratios are determined through computer simulation, mini-
mizing carryover of hazardous components and ensuring
retention of contaminants in the final waste form. Self-
sustaining immobilization does not require expensive
equipment and is economically justified, particularly for
small-volume hazardous wastes. The possibility of such
processes has been demonstrated for a number of waste
streams including calcined radioactive waste, contaminated
clay soils, ashes and spent inorganic ion exchangers, zirco-
nium alloys and irradiated graphite. New schemes are
designed to be applied in situ, ensuring waste immobiliz-
ation in the final disposal environment [28].
Thermodynamic simulation has been applied to the design
of appropriate PMF formulations [29, 30]. Ash residues
from radioactive waste incineration as well as contaminated
clay soil were used. The b,g-emitting radionuclides of cae-
sium, strontium and cobalt and the a-emitting radionuclides
of heavy metals (actinides, radium, and polonium) were the
main carriers of radioactivity in the ash residue. The radio-
nuclide content in the soil was represented mainly by137Cs. For U- and Pu-containing wastes, natural zircon was
added to the PMF to aid radionuclide retention [31].Table 7 illustrates the properties of the glass composites
obtained through a thermochemical solidification process
such as self-sustaining immobilization. The retention of
radionuclides by glass composite materials is due to high
leaching rates similar to those obtained by conventional
vitrification.
A significant advantage of the thermochemical immobil-
ization process is its autonomy: self-sustaining immobiliz-
ation can be carried out remotely without the need for a
processing area. This method has been proposed recently
for in situ immobilization of waste in borehole-type reposi-
tories [14, 27]. Figure 8 demonstrates the process occurring
in a double-walled container in field tests of in situ
immobilization.
Self-sustaining immobilization has been proven as a
feasible scheme to vitrify ashes produced as a result of
Table 7 Characteristics of self-sustaining immobilization processes and the glass composites obtained
Wastecontent
Processtemperature Density
Compressivestrength
Leach rate� (g/cm2 day)
(wt %) (8C) (g/cm3) (MPa) 137Cs 239Pu
Ash 50 1530 2.8 20 9.0 � 1026 5.4 � 1026
56 1356 2.8 17 4.9 � 1026 2.8 � 1026
60 1245 3.0 16 7.9 � 1025 7.0 � 1025
Soil 45 1905 2.4 10 1.0 � 1025 —50 1627 2.0 10 8.1 � 1026 —56 1530 1.5 8 2.1 � 1026 —
Clinoptilolite 55 1476 1.74 9 4.0 � 1025 —
�Normalized leach rates were measured according to IAEA test protocol ISO 6961-1982.
Fig. 8 Self-sustaining immobilization: (a) process within double-wall container crucible; (b) borehole in situ
testing experiment; (c) monolith block produced in situ
THERMOCHEMICAL PROCESSING USING POWDER METAL FUELS OF RADIOACTIVE AND HAZARDOUS WASTE 7
E04503 # IMechE 2004 Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering
incineration of solid radioactive waste, contaminated soils
and spent ion exchangers, e.g. clinoptilolite. An experimen-
tal ash vitrification plant has been under operation at
Moscow SIA ‘Radon’ for a number of years, and a modular
mobile facility is currently under development. The mobile
facility aims to immobilize ashes, soils and spent sorbents at
their point of generation [26].
7 CONCLUSIONS
Highly efficient thermochemical processes have been devel-
oped to process specific types of toxic and radioactive
waste. These are used for pretreatment (e.g. decontamina-
tion), treatment and conditioning of spent ion-exchange
resins, inorganic absorbents, irradiated graphite, organic
and biological wastes and contaminated soils. Thermo-
chemical processing is based on utilization of powder
metal fuels that can be specifically formulated for each indi-
vidual waste composition. Powder metal fuels selectively
react with the most hazardous constituents of the wastes
to minimize the release of toxic substances. The application
of thermochemical processing results in almost total con-
finement of contaminants in a mineral or glass-like end-
product. Technologies based on thermochemical processing
are simple in implementation and can be realized without
complex production equipment and energy supply.
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14 Sobolev, I. A., Kedrovsky, O. L., Myasoedov, B. F.,
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15 Dmitriev, S. A., Karlina, O. K., Ojovan, M. I., Petrov, A. G.,
Sobolev, I. A., Tivansky, V. M., Khrabrov, S. L.,
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17 Mamaev, L., Khrabrov, S., Tikhomirov, V., Ojovan, M. I.,
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8 M I OJOVAN, W E LEE, I A SOBOLEV, S A DMITRIEV, et al.
Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering E04503 # IMechE 2004
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22 Ojovan,M. I., Karlina, O. K., Klimov, V. L., Bergmam,G. A.,
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25 Karlina, O. K., Klimov, V. L., Pavlova, G. Yu.,
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THERMOCHEMICAL PROCESSING USING POWDER METAL FUELS OF RADIOACTIVE AND HAZARDOUS WASTE 9
E04503 # IMechE 2004 Proc. Instn Mech. Engrs Vol. 218 Part E: J. Process Mechanical Engineering
Proceedings of the Institution of Mechanical Engineers
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