U.S. patent application number 09/953442 was filed with the patent office on 2002-05-23 for method for treating organohalogen compound-containing soil or ash.
Invention is credited to Fujii, Yasuhiko, Hakata, Toshiyuki, Hatakeyama, Satoshi, Imai, Tomoyuki, Matsui, Toshiki, Okita, Tomoko.
Application Number | 20020059818 09/953442 |
Document ID | / |
Family ID | 18772875 |
Filed Date | 2002-05-23 |
United States Patent
Application |
20020059818 |
Kind Code |
A1 |
Imai, Tomoyuki ; et
al. |
May 23, 2002 |
Method for treating organohalogen compound-containing soil or
ash
Abstract
A process for treating an organohalogen compound-containing soil
or ash of the present invention, comprises: mixing the
organohalogen compound-containing soil or ash with an organohalogen
compound-decomposition catalyst composed of a composite catalyst
comprising an amine compound and iron compound particles, and
having an average particle size of 0.01 to 2.0 .mu.m, a phosphorus
content of not more than 0.02% by weight, a sulfur content of not
more than 0.3% by weight and a sodium content of not more than 0.3%
by weight; and having an apparent density (.rho.a) of not more than
0.8 g/ml and a catalytic activity capable of decomposing not less
than 50% by weight of monochlorobenzene; and heat-treating the
obtained mixture at a temperature of 150 to 600.degree. C. The
method for treating an organohalogen compound-containing soil or
ash in order to effectively decompose dioxins and dioxin precursors
such as aromatic organohalogen compounds or aliphatic organohalogen
compounds, e.g., trichloroethylene and dichloromethane, which are
contained in the soil or ash.
Inventors: |
Imai, Tomoyuki;
(Hiroshima-shi, JP) ; Hatakeyama, Satoshi;
(Hiroshima-ken, JP) ; Matsui, Toshiki;
(Hiroshima-shi, JP) ; Fujii, Yasuhiko; (Otake-shi,
JP) ; Okita, Tomoko; (Hatsukaichi-shi, JP) ;
Hakata, Toshiyuki; (Hiroshima-shi, JP) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
1100 North Glebe Road, 8th Floor
Arlington
VA
22201
US
|
Family ID: |
18772875 |
Appl. No.: |
09/953442 |
Filed: |
September 17, 2001 |
Current U.S.
Class: |
71/12 ;
588/316 |
Current CPC
Class: |
A62D 2101/22 20130101;
A62D 3/40 20130101; B09C 1/08 20130101; B09B 3/00 20130101; A62D
2101/28 20130101 |
Class at
Publication: |
71/12 ;
588/213 |
International
Class: |
A62D 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2000 |
JP |
2000-289482 |
Claims
What is claimed is:
1. A process for treating an organohalogen compound-containing soil
or ash, comprising: mixing the organohalogen compound-containing
soil or ash with an organohalogen compound-decomposition catalyst
composed of a composite catalyst comprising an amine compound and
iron compound particles, and having an average particle size of
0.01 to 2.0 .mu.m, a phosphorus content of not more than 0.02% by
weight, a sulfur content of not more than 0.3% by weight and a
sodium content of not more than 0.3% by weight; and having an
apparent density (.rho.a) of not more than 0.8 g/ml and a catalytic
activity capable of decomposing not less than 50% by weight of
monochlorobenzene when 50 mg of the composite catalyst is
heat-treated at 300.degree. C. for 60 minutes in air and then
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a space velocity of 150,000
h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor; and heat-treating the obtained mixture at a temperature of
150 to 600.degree. C.
2. A process according to claim 1, wherein the amount of said
organohalogen compound-decomposition catalyst used is 0.1 to 100
parts by weight based on 100 parts by weight of the organohalogen
compound-containing soil or ash.
3. A process according to claim 1, wherein the heat-treatment is
conducted under an air flow.
4. A process according to claim 1, wherein said iron compound
particles have a BET specific surface area of 0.2 to 200
m.sup.2/g.
5. A process according to claim 1, wherein said amine compound is
at least one compound selected from the group consisting of
alkylamines, alkanolamines and cyclic amines, and has a boiling
point of not less than 150.degree. C.
6. A process according to claim 1, wherein said amine compound is
contained in an amount of 0.01 to 10% by weight based on the weight
of the iron compound particles.
7. A process according to claim 1, wherein the BET specific surface
area of said organohalogen compound-decomposition catalyst is 0.2
to 200 m.sup.2/g.
8. A process according to claim 1, wherein the average particle
size of said organohalogen compound-decomposition catalyst is 0.01
to 2.0 .mu.m.
9. A process according to claim 1, wherein said soil or ash and
said organohalogen compound-decomposition catalyst are mixed
together by a dry mixing method using a sand mill, a Henschel
mixer, a concrete mixer or a Nauter mixer, or by a semi-dry mixing
method using a sand mill, a Henschel mixer, a concrete mixer, a
Nauter mixer or a single-screw or twin-screw kneader-type
mixer.
10. A process according to claim 1, wherein the heat-treatment is
conducted using a continuous- or batch-type rotary kiln,
multiple-hearth furnace or a batch continuous-type pressure
furnace.
11. A process according to claim 1, wherein the iron compound
particles have an average particle size of 0.01 to 2.0 .mu.m, a
phosphorus content of not more than 0.02% by weight, a sulfur
content of not more than 0.3% by weight and a sodium content of not
more than 0.3% by weight; and have a catalytic activity capable of
decomposing not less than 20% by weight of monochlorobenzene when
50 mg of the iron compound particles heat-treated at 300.degree. C.
for 60 minutes in air are instantaneously contacted with
5.0.times.10.sup.-7 mol of monochlorobenzene at 300.degree. C. at a
space velocity of 150,000 h.sup.-1 in an inert gas atmosphere using
a pulse catalytic reactor.
12. A process for treating an organohalogen compound-containing
soil or ash, comprising: mixing 100 parts by weight of the
organohalogen compound-containing soil or ash with 0.1 to 100 parts
by weight of an organohalogen compound-decomposition catalyst
composed of a composite catalyst comprising 0.01 to 10 parts by
weight of an amine compound having a boiling point of not less than
150.degree. C., and 100 parts by weight of iron compound particles
having an average particle size of 0.01 to 2.0 .mu.m, a phosphorus
content of not more than 0.02% by weight, a sulfur content of not
more than 0.3% by weight and a sodium content of not more than 0.3%
by weight; and having an average particle size of 0.01 to 2.0
.mu.m, an apparent density (.rho.a) of not more than 0.8 g/ml and a
catalytic activity capable of decomposing not less than 50% by
weight of monochlorobenzene when 50 mg of the composite catalyst is
heat-treated at 300.degree. C. for 60 minutes in air and then
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a space velocity of 150,000
h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor; and heat-treating the obtained mixture at a temperature of
150 to 600.degree. C. under an air flow.
13. A process for treating an organohalogen compound-containing
soil or ash, comprising: mixing 100 parts by weight of the
organohalogen compound-containing soil or ash with 0.1 to 100 parts
by weight an organohalogen compound-decomposition catalyst by a dry
mixing method using a sand mill, a Henschel mixer, a concrete mixer
or a Nauter mixer, or by a semi-dry mixing method using a sand
mill, a Henschel mixer, a concrete mixer, a Nauter mixer or a
single-screw or twin-screw kneader-type mixer; said organohalogen
compound-decomposition catalyst being composed of a composite
catalyst comprising 0.01 to 10 parts by weight of an amine compound
having a boiling point of not less than 150.degree. C., and 100
parts by weight of iron compound particles having an average
particle size of 0.01 to 2.0 .mu.m, a phosphorus content of not
more than 0.02% by weight, a sulfur content of not more than 0.3%
by weight and a sodium content of not more than 0.3% by weight; and
having an average particle size of 0.01 to 2.0 .mu.m, an apparent
density (.rho.a) of not more than 0.8 g/ml and a catalytic activity
capable of decomposing not less than 50% by weight of
monochlorobenzene when 50 mg of the composite catalyst is
heat-treated at 300.degree. C. for 60 minutes in air and then
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a space velocity of 150,000
h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor; and heat-treating the obtained mixture at a temperature of
150 to 600.degree. C. under an air flow using a continuous- or
batch-type rotary kiln, multiple-hearth furnace or a batch
continuous-type pressure furnace.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method for treating soil
or ash containing organohalogen compounds, and more particularly,
to a method for treating an organohalogen compound-containing soil
or ash in order to effectively decompose dioxins and dioxin
precursors such as aromatic organohalogen compounds or aliphatic
organohalogen compounds, e.g., trichloroethylene and
dichloromethane, which are contained in the soil or ash.
[0002] Exhaust gases, fly ashes and deposited ashes generated from
an incinerator upon burning municipal solid wastes and industrial
wastes therein, contain dioxins which are aromatic halogen
compounds showing an extremely strong toxicity to human bodies,
though the contents thereof are very small. The dioxins generally
include compounds having such a structure that hydrogen atoms of
dibenzo-p-dioxine, dibenzofuran, etc. are substituted with chlorine
atoms.
[0003] Also, the aliphatic organohalogen compounds such as
trichloroethylene and tetrachloroethylene have been extensively
used in many applications such as degreasing of metals,
dry-cleaning and the like.
[0004] The organohalogen compounds have caused significant
environmental problems such as air pollution due to discharge
thereof into atmospheric air, and contamination of ground water and
soils upon disposal thereof, because these compounds are difficult
to decompose and show carcinogenesis. In particular, ashes
discharged from incinerators or soils contaminated with wastes have
a high content of the organohalogen compounds. Therefore, it has
been required to decompose these organohalogen compounds and
convert these compounds into harmless ones. Although various
methods for removing the organohalogen compounds have been
conventionally proposed, satisfactory techniques capable of
decomposing the organohalogen compounds and converting these
compounds into harmless ones in economical and effective manner,
have not been established.
[0005] Hitherto, various techniques for decomposing organohalogen
compounds contained in soils or ashes and converting these
compounds into harmless ones have been reported. For example, there
are known a method of decomposing poly-halogenated aromatic
compounds having at least five carbon atoms by heating at a
temperature of 200 to 550.degree. C. in the presence of a catalyst
such as iron oxide (Japanese Patent Publication (KOKOKU) No.
6-38863(1994)); a method of removing halogenated aromatic compounds
or the like from an exhaust gas or reducing amounts thereof by
heat-treating at a temperature of 300 to 700.degree. C. in the
presence of a catalyst containing iron oxide (Japanese Patent
Application Laid-Open (KOAKI) No. 2-280816(1990)); a method of
introducing an inhibitor for preventing the generation of dioxins
composed of an amine-carrying activated carbon, into an exhaust gas
passing through flues of an incinerator (Japanese Patent
Application Laid-Open (KOAKI) No. 11-9960(1999)); a method of
mixing ashes to be treated, and a dechlorinating agent, and then
heat-treating the resultant mixture (Japanese Patent Application
Laid-Open (KOAKI) No. 11-19616(1999)); a method of decomposing
organohalogen compounds in the presence of oxygen using a solid
catalyst containing iron oxide, etc. and/or titanium dioxide as
base components (Japanese Patent Application Laid-Open (KOAKI) Nos.
11-188235(1999) and 11-188236(1999)); a method of adding
phosphorous acids, hypophosphorous acids with an aluminum compound,
and/or a titanium compound to solid wastes and then heat-treating
the resultant mixture (Japanese Patent Application Laid-Open
(KOAKI) No. 11-290824(1999)); or the like.
[0006] In addition, there are also known an iron compound catalyst
having a specific catalytic activity, and a method of spraying the
iron compound catalyst into a combustion chamber of an incinerator
in order to prevent the generation of dioxins (Japanese Patent
Application Laid-Open (KOAKI) No. 11-267507(1999)).
[0007] However, although it has been presently required to provide
an process for decomposing the organohalogen compounds contained in
soils or ashes and converting these compounds into harmless ones,
the methods described in the above publications are still
unsatisfactory.
[0008] Namely, in the method described in Japanese Patent
Publication (KOKOKU) No. 6-38863(1994), poly-halogenated compounds
which are contained in fly ashes generated in an incinerator or
solid wastes are decomposed under an oxygen-lack atmosphere or an
inert gas atmosphere in a non-pass-through-type or closed-type
apparatus using fly ashes, metals, metal oxides containing iron
oxide, carbonates, silicates and the like as a catalyst. However,
this method must be performed under the specific conditions, i.e.,
under the closed system or the inert gas atmosphere, thereby
requiring large-scale apparatuses with high air-tightness as well
as high costs for installation and maintenance thereof. Therefore,
the above method is unsatisfactory from industrial viewpoints.
[0009] In the method described in Japanese Patent Application
Laid-Open (KOAKI) No. 11-19616(1999), after incineration ashes, fly
ashes or the like are mixed with a dechlorinating agent composed of
alkali substances, the resultant mixture is heat-treated. In this
method, it is required to contact chlorine-containing gases
generated by heating the wastes to be treated, with the alkali
substances. Thus, the wastes to be treated must be heated to an
elevated temperature in order to generate the chlorine-containing
gases. Namely, the method is not directly concerned with such
techniques for decomposing the organohalogen compounds and
converting these compounds into harmless ones. Therefore, the above
method is also unsatisfactory to convert dioxins into harmless
compounds.
[0010] In the method described in Japanese Patent Application
Laid-Open (KOAKI) No. 11-9960(1999), the amine-carrying activated
carbon is introduced into exhaust gases containing dioxins in order
to adsorb the dioxins in the activated carbon by high adsorptivity
of the activated carbon, and then react the dioxins with the amine
compound for decomposition of the dioxins. The amine-carrying
activated carbon exhibits a high dioxin-adsorptivity, but is
insufficient in dioxin-decomposition activity. Further, the
activated carbon cannot sufficiently prevent the generation of
dioxins. Also, the activated carbon tends to be ignitable and
flammable when heated to an elevated temperature. Therefore, the
above method is undesirable in view of safety.
[0011] In the method described in Japanese Patent Application
Laid-Open (KOAKI) Nos. 11-188235(1999) and 11-188236(1999),
organohalogen compounds contained in gases are decomposed in the
presence of oxygen using a solid catalyst containing iron oxide,
etc. and/or titanium dioxide as base components. Thus, the
organohalogen compounds treated by the method are only those
contained in gases, the above method is unsatisfactory for
decomposing organohalogen compounds contained in solids.
[0012] In the method described in Japanese Patent Application
Laid-Open (KOAKI) No. 11-290824(1999), there is used a treating
agent containing phosphorous acids and hypophosphorous acids. As
shown in Comparative Examples below, the treating agent is poor in
dioxin-decomposition percentage. Therefore, the above method is
also unsatisfactory for decomposing dioxins.
[0013] Further, the catalyst described in Japanese Patent
Application Laid-Open (KOAKI) No. 11-267507(1999), is effective to
reduce the amount of dioxins contained in soils or ashes. However,
the activity of the catalyst is still unsatisfactory as shown in
Comparative Examples below.
[0014] As a result of the present inventors' earnest studies for
solving the above problems, it has been found that by mixing
organohalogen compound-containing soil or ash with a specific
organohalogen compound-decomposition catalyst and then
heat-treating the resultant mixture at a temperature of 150 to
600.degree. C., it is possible to effectively decompose dioxins or
dioxin precursors contained in the soil or ash. The present
invention has been attained on the basis of this finding.
SUMMARY OF THE INVENTION
[0015] It is an object of the present invention to provide a method
for effectively treating an organohalogen compound-containing soil
or ash using a simple apparatus without specifying a gas
atmosphere, in order to decompose dioxins as well as dioxin
precursors such as aromatic organohalogen compounds and aliphatic
organohalogen compounds, e.g., trichloroethylene, dichloromethane
or the like, which are contained in the soil or ash.
[0016] To accomplish the aim of the present invention, there is
provided a process for treating an organohalogen
compound-containing soil or ash, comprising:
[0017] mixing the organohalogen compound-containing soil or ash
with an organohalogen compound-decomposition catalyst composed of a
composite catalyst comprising an amine compound and iron compound
particles, and having an average particle size of 0.01 to 2.0
.mu.m, a phosphorus content of not more than 0.02% by weight, a
sulfur content of not more than 0.3% by weight and a sodium content
of not more than 0.3% by weight; and having an apparent density
(.rho.a) of not more than 0.8 g/ml and a catalytic activity capable
of decomposing not less than 50% by weight of monochlorobenzene
when 50 mg of the organohalogen compound-decomposition catalyst is
heat-treated at 300.degree. C. for 60 minutes in air and then
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a space velocity of 150,000
h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor; and
[0018] heat-treating the obtained mixture at a temperature of 150
to 600.degree. C.
[0019] In a second aspect of the present invention, there is
provided a process for treating an organohalogen
compound-containing soil or ash, comprising:
[0020] mixing 100 parts by weight of the organohalogen
compound-containing soil or ash with 0.1 to 100 parts by weight of
an organohalogen compound-decomposition catalyst composed of a
composite catalyst comprising 0.01 to 10 parts by weight of an
amine compound having a boiling point of not less than 150.degree.
C., and 100 parts by weight of iron compound particles, and having
an average particle size of 0.01 to 2.0 .mu.m, a phosphorus content
of not more than 0.02% by weight, a sulfur content of not more than
0.3% by weight and a sodium content of not more than 0.3% by
weight; and having an average particle size of 0.01 to 2.0 .mu.m,
an apparent density (.rho.a) of not more than 0.8 g/ml and a
catalytic activity capable of decomposing not less than 50% by
weight of monochlorobenzene when 50 mg of the organohalogen
compound-decomposition catalyst is heat-treated at 300.degree. C.
for 60 minutes in air and then instantaneously contacted with
5.0.times.10.sup.-7 mol of monochlorobenzene at 300.degree. C. at a
space velocity of 150,000 h.sup.-1 in an inert gas atmosphere using
a pulse catalytic reactor; and
[0021] heat-treating the obtained mixture at a temperature of 150
to 600.degree. C. under an air flow.
[0022] In a third aspect of the present invention, there is
provided a process for treating an organohalogen
compound-containing soil or ash, comprising:
[0023] mixing 100 parts by weight of an organohalogen
compound-containing soil or ash with 0.1 to 100 parts by weight an
organohalogen compound-decomposition catalyst by a dry mixing
method using a sand mill, a Henschel mixer, a concrete mixer or a
Nauter mixer, or by a semi-dry mixing method using a sand mill, a
Henschel mixer, a concrete mixer, a Nauter mixer or a single-screw
or twin-screw kneader-type mixer;
[0024] the organohalogen compound-decomposition catalyst being
composed of a composite catalyst comprising 0.01 to 10 parts by
weight of an amine compound having a boiling point of not less than
150.degree. C. and 100 parts by weight of iron compound particles,
and having an average particle size of 0.01 to 2.0 .mu.m, a
phosphorus content of not more than 0.02% by weight, a sulfur
content of not more than 0.3% by weight and a sodium content of not
more than 0.3% by weight; and having an average particle size of
0.01 to 2.0 .mu.m, an apparent density (.rho.a) of not more than
0.8 g/ml and a catalytic activity capable of decomposing not less
than 50% by weight of monochlorobenzene when 50 mg of the
organohalogen compound-decomposition catalyst is heat-treated at
300.degree. C. for 60 minutes in air and then instantaneously
contacted with 5.0.times.10.sup.-7 mol of monochlorobenzene at
300.degree. C. at a space velocity of 150,000 h.sup.-1 in an inert
gas atmosphere using a pulse catalytic reactor; and
[0025] heat-treating the obtained mixture at a temperature of 150
to 600.degree. C. under an air flow using a continuous- or
batch-type rotary kiln, multiple-hearth furnace or a batch
continuous-type pressure furnace.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The present invention will now be described in detail
below.
[0027] First, an organohalogen compound-decomposition catalyst used
in the method of the present invention is described.
[0028] The organohalogen compound-decomposition catalyst used in
the method of the present invention is constituted by a composite
catalyst comprising iron compound particles and an amine
compound.
[0029] The iron compound particles used in the present invention
have an average particle size of usually 0.01 to 2.0 .mu.m,
preferably 0.02 to 2.0 .mu.m, more preferably 0.02 to 1.0
.mu.m.
[0030] When the average particle size of the iron compound
particles is more than 2.0 .mu.m, the contact efficiency between
the obtained decomposition catalyst and the organohalogen compounds
is deteriorated, so that the decomposition catalyst may fail to
show a sufficient organohalogen compound-decomposition activity.
The mass-production of the iron compound particles having an
average particle size of less than 0.01 .mu.m, is industrially
difficult. Further, a large amount of energy is required to
pulverize agglomerated particles produced by a large coagulation
force between too fine particles. Therefore, the use of such fine
iron compound particles becomes difficult practically.
[0031] The iron compound particles used in the present invention,
have a BET specific surface area of usually 0.2 to 200 m.sup.2/g,
preferably 1.0 to 200 m.sup.2/g, more preferably 2.0 to 150
m.sup.2/g.
[0032] As the iron compound particles used in the present
invention, there may be exemplified iron oxide hydroxide particles
such as goethite, akaganeite and lepidocrocite; and iron oxide
particles such as hematite, maghemite and magnetite. These iron
compound particles may be used alone or in combination of any two
or more thereof. Among these iron compound particles, goethite
particles, hematite particles and magnetite particles are
preferred, and goethite particles and hematite particles are more
preferred.
[0033] The iron compound particles used in the present invention
may be granular particles having either a spherical shape, a
cubical shape, an octahedral shape, a hexahedral shape and a
polyhedral shape, or acicular particles having either an
needle-like shape, a spindle shape or a rice-grain shape. Among
these particles, spindle-shaped particles or acicular particles are
preferred.
[0034] The iron compound particles used in the present invention,
have a phosphorus content of usually not more than 0.02% by weight,
preferably not more than 0.01% by weight, more preferably not more
than 0.005% by weight based on the weight of the particles. When
the phosphorus content is more than 0.02% by weight, since the
catalyst poison ability of the phosphorus becomes large, the
catalytic activity for the decomposition of the organohalogen
compounds may be deteriorated.
[0035] The iron compound particles used in the present invention,
have a sulfur content of usually not more than 0.3% by weight,
preferably not more than 0.1% by weight, more preferably not more
than 0.07% by weight based on the weight of the particles. When the
sulfur content is more than 0.3% by weight, since the catalyst
poison ability of the sulfur becomes large, the catalytic activity
for the decomposition of the organohalogen compounds may be
deteriorated.
[0036] The iron compound particles used in the present invention,
have a sodium content of usually not more than 0.3% by weight,
preferably not more than 0.2% by weight, more preferably not more
than 0.15% by weight based on the weight of the particles. When the
sodium content is more than 0.3% by weight, since the catalyst
poison ability of the sodium becomes large, the catalytic activity
for decomposition of the organohalogen compounds may be
deteriorated.
[0037] Further, the iron compound particles used in the present
invention, have a total content of phosphorus, sulfur and sodium of
preferably not more than 0.5% by weight, more preferably not more
than 0.3% by weight, still more preferably not more than 0.2% by
weight based on the weight of the particles. When the total content
of phosphorus, sulfur and sodium is more than 0.5% by weight, the
catalytic activity for decomposition of the organohalogen compounds
may be deteriorated.
[0038] The iron compound particles used in the present invention
exhibit a catalytic activity capable of decomposing not less than
20% of monochlorobenzene when measured by the following method.
That is, 50 mg of iron oxide particles obtained by heat-treating
the above iron compound particles at 300.degree. C. for 60 minutes
in air, is instantaneously contacted with 5.0.times.10.sup.-7 mol
of monochlorobenzene at 300.degree. C. at a hourly space velocity
of 150,000 h.sup.-1 in an inert gas atmosphere using a pulse
catalytic reactor to determine the percentage of the
monochlorobenzene decomposed.
[0039] In case of composite catalyst produced by using the iron
compound particles having the decomposition activity of
monochlorobenzene of less than 20%, the aimed effects of the
present invention cannot be obtained. The iron compound particles
have a catalytic activity capable of decomposing monochlorobenzene
of preferably not less than 25%, more preferably not less than 30%.
That is, 50 mg of the iron compound particles are heat-treated at
300.degree. C. for 60 minutes in air and then instantaneously
contacted with 5.0.times.10.sup.-7 mol of monochlorobenzene at
300.degree. C. at a hourly space velocity of 150,000 h.sup.-1 in an
inert gas atmosphere using a pulse catalytic reactor to determine
the percentage of the monochlorobenzene decomposed.
[0040] Examples of the amine compound used in the present invention
may include alkylamines such as diethylenetriamine and
triethylenetetramine; alkanolamines such as triethanolamine and
diethanolamine; cyclic amines such as aniline; or the like. These
amine compounds may be used alone or in combination of any two or
more thereof.
[0041] The amine compound used in the present invention has a
boiling point of usually not less than 150.degree. C. When the
boiling point of the amine compound is less than 150.degree. C.,
the amine compound tends to be vaporized when treating the
organohalogen compounds therewith, so that the obtained
organohalogen compound-decomposition catalyst may fail to show the
aimed effects of the present invention.
[0042] The organohalogen compound-decomposition catalyst of the
present invention has substantially the same particle shape,
particle size and the content of the impurities such as phosphorus,
sulfur, sodium or the like as those of the iron compound particles
used. More specifically, the organohalogen compound-decomposition
catalyst has an average particle size of usually 0.01 to 2.0 .mu.m,
preferably 0.02 to 2.0 .mu.m, more preferably 0.02 to 1.0 .mu.m.
The organohalogen compound-decomposition catalyst has a phosphorus
content of usually not more than 0.02% by weight, preferably not
more than 0.01% by weight, more preferably not more than 0.005% by
weight based on the weight of the composite particles. The
organohalogen compound-decomposition catalyst has a sulfur content
of usually not more than 0.3% by weight, preferably not more than
0.1% by weight, more preferably not more than 0.07% by weight based
on the weight of the composite particles. The organohalogen
compound-decomposition catalyst has a sodium content of usually not
more than 0.3% by weight, preferably not more than 0.2% by weight,
more preferably not more than 0.15% by weight based on the weight
of the composite particles. The organohalogen
compound-decomposition catalyst has have a total content of
phosphorus, sulfur and sodium of preferably not more than 0.5% by
weight, more preferably not more than 0.3% by weight, still more
preferably not more than 0.2% by weight based on the weight of the
composite particles.
[0043] Also, the organohalogen compound-decomposition catalyst of
the present invention has an apparent density (.rho.a) of usually
not more than 0.8 g/ml, preferably not more than 0.6 g/ml. When the
apparent density of the organohalogen compound-decomposition
catalyst is more than 0.8 g/ml, the pulverization of agglomerated
particles may be insufficiently conducted, so that it is difficult
to intimately mix the organohalogen compound-decomposition catalyst
with materials to be treated.
[0044] The organohalogen compound-decomposition catalyst of the
present invention has a BET specific surface area of preferably 0.2
to 200 m.sup.2/g, more preferably 1.0 to 200 m.sup.2/g, still more
preferably 2.0 to 150 m.sup.2/g.
[0045] The amount of the amine compound contained in the
organohalogen compound-decomposition catalyst is preferably 0.01 to
10 parts by weight, more preferably 0.05 to 5.0 parts by weight
based on the weight of the iron compound particles. When the
content of the amine compound is less than 0.01 part by weight, the
amine compound may show an insufficient effect of promoting the
decomposition of organohalogen compounds because of a small amount
of the amine compound contained in the catalyst. When the content
of the amine compound is more than 10 parts by weight, the
organohalogen compound-decomposition activity thereof may lower
because of a small amount of the iron compound particles contained
in the composite catalyst.
[0046] The organohalogen compound-decomposition catalyst of the
present invention exhibits a catalytic activity capable of
decomposing preferably not less than 50%, more preferably not less
than 55%, still more preferably not less than 60% of
monochlorobenzene when measured by the following method. That is,
50 mg of the organohalogen compound-decomposition catalyst is
heat-treated at 300.degree. C. for 60 minutes in air and then
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a hourly space velocity of
150,000 h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor to determine the percentage of the monochlorobenzene
decomposed. Incidentally, the catalytic activity obtained by the
above is substantially equal to a value when measured by the
method: 50 mg of a composite material produced from iron oxide
particles obtained by heat-treating the iron compound particles at
300.degree. C. for 60 minutes in air and the amine compound, is
instantaneously contacted with 5.0.times.10.sup.-7 mol of
monochlorobenzene at 300.degree. C. at a hourly space velocity of
150,000 h.sup.-1 in an inert gas atmosphere using a pulse catalytic
reactor.
[0047] When the catalytic activity of the organohalogen
compound-decomposition catalyst for the decomposition of
monochlorobenzene is less than 50%, it is difficult to effectively
decompose the organohalogen compounds.
[0048] In general, since monochlorobenzene is a typical one of the
organohalogen compounds and is also known as a precursor of dioxin,
the catalytic activity for the decomposition of monochlorobenzene
is regarded as an index of the catalytic activity for the
decomposition of the organohalogen compounds such as dioxins.
Meanwhile, the decomposition percentage (conversion) of
monochlorobenzene is represented by the following formula:
Conversion (%)=[1-(amount of monochlorobenzene detected after
reaction/amount of monochlorobenzene initially
charged)].times.100
[0049] Next, the process for producing the organohalogen
compound-decomposition catalyst of the present invention is
described.
[0050] First, the process for producing the iron compound used in
the present invention is described.
[0051] Among the iron compounds used in the present invention, the
acicular-shaped, a spindle-shaped or a rice-grain-shaped goethite
particles and granular-shaped magnetite particles may be produced,
for example, by passing an oxygen-containing gas such as air
through a suspension containing a ferrous-containing precipitate
such as hydroxides of iron or iron carbonates which are obtained by
reacting a ferrous salt with at least one compound selected from
the group consisting of alkali hydroxides, alkali carbonates and
ammonia.
[0052] Among the iron compounds used in the present invention, the
hematite particles may be produced, for example, by
heat-dehydrating or heat-treating the above obtained goethite
particles or magnetite particles at a temperature of 200 to
800.degree. C. in air; the magnetite particles may be produced, for
example, by heat-reducing the above obtained goethite particles or
hematite particles at a temperature of 300 to 600.degree. C. in a
reducing atmosphere; and the maghemite particles may be produced,
for example, by heat-oxidizing the above obtained magnetite
particles in a temperature of 200 to 600.degree. C. in air.
[0053] In the production of the iron compound used in the present
invention, it is necessary to restrict the contents of phosphorus,
sulfur and sodium as catalyst poisons to not more than the
above-mentioned predetermined amounts. More specifically, as the
ferrous iron salt solution, there may be preferably used those
having low contents of phosphorus, sulfur and the like as catalyst
poisons. In addition, the contents of phosphorus, sulfur and sodium
are preferably reduced by avoiding the use of sodium
hexametaphosphate or the like usually added as a sintering
preventive upon heat-calcination step, and by removing sulfate ions
derived from the raw ferrous materials or sodium ions derived from
raw alkali materials by means of purification treatments such as
washing with water or the like.
[0054] Meanwhile, the iron compound particles may be previously
deaggregated in order to reduce the apparent density of the
obtained composite catalyst.
[0055] The composite catalyst composed of the iron compound
particles and the amine compound may be produced by dry-mixing the
iron compound particles with the amine compound using mixers such
as a sand mill, a Henschel mixer and a Nauter mixer, or pulverizers
such as a fine mill and a pin mill.
[0056] In the above dry-mixing treatment, a solvent such as water
or alcohol (e.g. ethanol or isopropyl alcohol) may be present
therein, if required, in order to improve a wettability of the
particles. When any solvent is used, it is preferred that the
solvent be evaporated by heating or under reduced pressure after
the dry-mixing treatment.
[0057] The above dry-mixing treatment is preferably conducted under
the following conditions.
[0058] In case of using the sand mill, the dry-mixing is conducted
at a linear load of 5 to 50 Kg for 15 to 90 minutes.
[0059] In case of using the Henschel mixer, the dry-mixing is
conducted at a temperature of 10 to 100.degree. C. and a stirring
speed of 500 to 3,000 rpm for 1 to 30 minutes.
[0060] In case of using the Nauter mixer, the dry-mixing is
conducted at a rotating velocity of 25 to 200 rpm and a revolving
velocity of 1 to 5 rpm for 15 to 60 minutes.
[0061] In case of using the fine mill or pin mill, the milling or
dry-mixing is conducted at a stirring speed of 1,000 to 10,000 rpm
while adding the amine compound to the iron compound particles.
[0062] The thus obtained composite particles constituting the
organohalogen compound-decomposition catalyst of the present
invention have such a configuration that the amine compound is
carried on a part of the surface of each iron compound
particle.
[0063] Next, the method for treating the organohalogen
compound-containing soil or ash is described.
[0064] In the treating method of the present invention, the
organohalogen compound-containing soil or ash and the organohalogen
compound-decomposition catalyst are first mixed together, and then
heat-treated.
[0065] Thus, in the present invention, the soil or ash is
previously mixed with the organohalogen compound-decomposition
catalyst. The mixing may be conducted by an ordinary dry-mixing
method using a sand mill, a Henschel mixer, a concrete mixer and a
Nauter mixer; a semi-dry-mixing method using the above-mentioned
mixers as well as a single-screw or twin-screw kneader-type mixer
in which water may be added thereto, if required; or the like. The
resultant mixture may be further subjected to compression-molding
or the like molding method in order to enhance the contact
efficiency between the organohalogen compound-decomposition
catalyst and the ash or soil to be treated.
[0066] The amount of the organohalogen compound-decomposition
catalyst added is preferably 0.1 to 100 parts by weight, more
preferably 1.0 to 50 parts by weight, still more preferably 1.0 to
30 parts by weight based on 100 parts by weight of the materials to
be treated. When the amount of the organohalogen
compound-decomposition catalyst added is less than 0.1 part by
weight, the aimed dioxin-decomposition effect of the present
invention cannot be sufficiently obtained. When the amount of the
organohalogen compound-decomposition catalyst added is more than
100 parts by weight, the aimed effect is already saturated.
Therefore, the use of such a large amount of the organohalogen
compound-decomposition catalyst is unnecessary and meaningless.
[0067] The above heat-treatment may be conducted in air, an
oxygen-containing gas or an inert gas atmosphere, within a closed
container or the like, though not particularly restricted. It is
possible to enhance the oxidative decomposition efficiency, by
conducting the heat-treatment under an oxygen-containing gas
flow.
[0068] The treating temperature may be varied according to the
reaction time, and is preferably 150 to 600.degree. C., more
preferably 200 to 400.degree. C. When the treating temperature is
less than 150.degree. C., the decomposition activity of the
organohalogen compound-decomposition catalyst may be deteriorated.
When the treating temperature is more than 600.degree. C., although
the organohalogen compounds can be decomposed, the effect of
decomposing the organohalogen compounds cannot be enhanced to such
a high level as estimated from a large energy required for the
heating.
[0069] The heat-treatment of the present invention may be conducted
using a continuous-type or batch-type rotary kiln, multiple-hearth
furnace or a batch continuous-type pressure furnace. Among them,
the use of the continuous-type or batch-type rotary kiln,
multiple-hearth furnace is preferred.
[0070] When the organohalogen compound-containing soil or ash is
treated by the process of the present invention, it is possible to
reduce the organohalogen compound content in the soil or ash up to
not more than 20%, preferably not more than 17%, more preferably
not more than 10% of the organohalogen compound content in
untreated soil or ash.
[0071] In case of treating soil or ash with the specific
organohalogen compound-decomposition catalyst of the present
invention, the organohalogen compounds contained in the soil or ash
can be effectively and economically decomposed.
[0072] The reason why the organohalogen compounds contained in the
soil or ash can be effectively decomposed, is considered as
follows. That is, it is considered that the organohalogen
compound-decomposition catalyst can exhibit a high catalytic
activity for the decomposition of organohalogen compounds, and can
be sufficiently contacted with the soil or ash.
[0073] The reason why the organohalogen compound-decomposition
catalyst can exhibit a high catalytic activity for the
decomposition of organohalogen compounds, is considered as follows.
That is, it is considered that the iron compound itself can exhibit
an excellent decomposition activity for the organohalogen
compounds; the amine compound carried on a part of the surface of
each iron compound particle can accelerate the adsorption of the
organohalogen compounds thereonto; and both the iron compound and
the amine compound can be contacted with each other, so that the
decomposition reaction of the organohalogen compounds adsorbed by
the amine compound can be accelerated. Further, it is considered
that the amine compound can accelerate not only the adsorption of
the organohalogen compounds but also the dechlorination reaction
thereof.
[0074] Also, since the organohalogen compound-decomposition
catalyst of the present invention has a low apparent density, the
soil or ash to be treated can be readily mixed therewith, and the
resultant mixture can be kept under a close contact condition.
[0075] Thus, the process for treating the organohalogen
compound-containing soil or ash according to the present invention,
can effectively decompose dioxins or dioxin precursors and,
therefore, is suitable as the process for treating the soil or
ash.
EXAMPLES
[0076] The present invention is described in more detail by
Examples and Comparative Examples, but the Examples are only
illustrative and, therefore, not intended to limit the scope of the
present invention.
[0077] Various properties were measured by the following
methods.
[0078] (1) The average particle size of the iron compound particles
and the composite catalyst was expressed by the average of values
measured from an electron micrograph. The specific surface area of
the iron compound particles and the composite catalyst was
expressed by the value measured by a BET method. The apparent
density (.rho.a) of the iron compound particles and the composite
catalyst was expressed by the value measured by the method defined
in JIS K5101.
[0079] (2) The contents of phosphorus and sodium contained in the
iron compound particles and the composite catalyst were expressed
by the values measured by an inductively coupled plasma atomic
emission spectrometer (SPS-4000 Model, manufactured by Seiko Denshi
Kogyo Co., Ltd.).
[0080] (3) The content of sulfur contained in the iron compound
particles and the composite catalyst was expressed by the value
measured by a Carbon-Sulfur Analyzer (EMIA-2200 Model, manufactured
by Horiba Seisakusho Co., Ltd.).
[0081] (4) The catalyst property of the composite catalyst was
measured by the following method.
[0082] That is, 50 mg of the composite catalyst was heat-treated at
300.degree. C. for 60 minutes in air and then instantaneously
contacted with 5.0.times.10.sup.-7 mol of monochlorobenzene at
300.degree. C. at an hourly space velocity of 150,000 h.sup.-1 in
an inert gas atmosphere using a pulse catalytic reactor. The
catalyst property of the composite catalyst is determined by
measuring the amount of monochlorobenzene decomposed in the above
process.
[0083] The pulse catalytic reactor used above is constituted by a
reactor portion and a gas chromatography portion which is
constituted by Gas Chromatography-Mass Spectroscopy GC/MSQP-5050
(manufactured by Shimadzu Co., Ltd.).
[0084] Meanwhile, the evaluation method used herein was conducted
by referring to methods described in the literatures (e.g., R. J.
Kobes, et al, "J. Am. Chem. Soc.", 77, 5860(1955) or "Experimental
Chemistry II-Reaction and Velocity" edited by Chemical Society of
Japan and published by Maruzen, Tokyo (1993)).
Example 1
[0085] <Iron Compound Particles>
[0086] As the iron compound particles 1, there were used
spindle-shaped goethite particles having an average particle size
of 0.25 .mu.m, a phosphorus content of 0.002% by weight, a sulfur
content of 0.05% by weight, a sodium content of 0.08% by weight and
a BET specific surface area of 85 m.sup.2/g.
[0087] When measured by the above evaluation method, the goethite
particles exhibited a monochlorobenzene decomposition percentage at
a temperature of 300.degree. C. of 32%.
[0088] <Production of Organohalogen Compound-Decomposition
Catalyst>
[0089] 1.5 kg of the above spindle-shaped goethite particles and 75
g of triethanolamine (boiling point: 360.degree. C.)(5.0% by weight
based on the weight of the goethite particles) were dry-mixed
together at a temperature of 50.degree. C. for 5 minutes in a
Henschel mixer (nominal capacity: 10 liters) operated at 1,440 rpm,
thereby obtaining goethite particles carrying triethanolamine
thereon (amount of triethanolamine: 5.0% by weight based on the
weight of the goethite particles).
[0090] The thus obtained triethanolamine-carrying goethite
particles (composite particles 1) had an average particle size of
0.25 .mu.m, a phosphorus content of 0.002% by weight, a sulfur
content of 0.05% by weight, a sodium content of 0.08% by weight, a
BET specific surface area of 78 m.sup.2/g and an apparent density
of 0.43 g/ml, and exhibited a monochlorobenzene decomposition
percentage at a temperature of 300.degree. C. of 88% when measured
by the above evaluation method.
[0091] <Decomposition Test for Dioxins>
[0092] 400 g of fly ashes sampled beneath an electric dust
collector in an incineration facility for municipal solid wastes
(concentration of dioxins: 6.9 ng-TEQ/g) and 4 g of the
above-prepared triethanolamine-carrying goethite particles (1.0
part by weight based on 100 parts by weight of the fly ashes to be
treated) were dry-mixed together for 0.5 minute in a Henschel mixer
(nominal capacity: 10 liters) operated at 1,440 rpm. Next, the
resultant mixture was transferred into a batch-type rotary kiln
having a capacity of 11 liters, and heat-treated therein at a
temperature of 300.degree. C. under an air flow (flow rate: 3
liters/min.) for 60 minutes.
[0093] <Measurement of Concentration of Dioxins>
[0094] The measurement of the concentration of dioxins contained in
the fly ashes was conducted by the "Method for Measurement of
Dioxins and Coplanar PCB" prescribed in Notification No. 6 of
Ministry of Public Welfare. As a result, it was confirmed that the
concentration of dioxins contained in the fly ashes was reduced to
0.32 ng-TEQ/g, namely 4.6% of the dioxin content of untreated fly
ashes.
[0095] <Iron Compounds 2 to 7>
[0096] As the iron compound for the organohalogen
compound-decomposition catalyst, iron compounds 2 to 7 were
prepared. The iron compound 7 has an apparent density of 0.98
g/ml.
[0097] <Composite Catalysts 2 to 10>
[0098] As the organohalogen compound-decomposition catalyst,
composite catalysts 2 to 10 were prepared. In the composite
catalyst 7, silica gel having no catalytic activity in itself was
used instead of the iron compound. Various properties of the
obtained composite catalysts are shown in Table 2. The composite
catalyst 10 was obtained by dry-mixing the iron compound 7 with
aniline in Nauter mixer (rotating velocity: 30 rpm, revolving
velocity: 2 rpm, mixing time: 5 minutes).
Examples 2 to 7, Comparative Examples 1 to 8 and Reference Examples
1 and 2
[0099] <Decomposition Test for Dioxins>
[0100] The same decomposition test for organohalogen compounds
contained in ashes or soil as defined in Example 1 was conducted
except that kind of ash, kind of composite catalyst, heat-treating
atmosphere, heat-treating temperature and retention time were
varied.
[0101] Various test conditions used in the decomposition test for
dioxins and the results thereof are shown in Table 3. In
Comparative Example 2, the heat-treatment was conducted using no
catalyst. In Comparative Example 5, the heat-treatment was
conducted using calcium hypophosphite (reagent produced by Kanto
Kagaku Co., Ltd.; purity: not less than 80%) as a catalyst.
Further, analyzed values of ashes before the treatment are also
shown in Table 4 and analyzed values of soil before the treatment
are also shown in Table 5.
1 TABLE 1 Average particle BET specific Iron compound size surface
area catalyst Kind (.mu.m) (m.sup.2/g) Iron compound 1 Goethite
0.25 85 Iron compound 2 Goethite 0.32 52 Iron compound 3 Hematite
0.26 101 Iron compound 4 Goethite 0.30 71 Iron compound 5 Hematite
0.10 11 Iron compound 6 Hematite 0.62 32 Iron compound 7 Hematite
0.25 43 Catalyst property (Conversion of Iron Phosphorus Sulfur
Sodium chlorobenzene at compound content content content
300.degree. C.) catalyst (wt. %) (wt. %) (wt. %) (%) Iron 0.002
0.05 0.08 32 compound 1 Iron 0 0.01 0.05 28 compound 2 Iron 0.002
0.01 0.07 33 compound 3 Iron 0.49 0.08 0.18 2 compound 4 Iron 0.01
0.17 0.48 3 compound 5 Iron 0 0.38 0.09 2 compound 6 Iron 0.002
0.05 0.10 27 compound 7
[0102]
2 TABLE 2 Amine compound Iron Boiling Composite compound and point
catalysts silica gel Kind (.degree. C.) Composite Iron
Triethanolamine 360 catalyst 1 compound 1 Composite Iron
Triethylenetetramine 278 catalyst 2 compound 2 Composite Iron
Aniline 184 catalyst 3 compound 3 Composite Iron Triethanolamine
360 catalyst 4 compound 1 Composite Iron Triethanolamine 360
catalyst 5 compound 4 Composite Iron Triethylenetetramine 278
catalyst 6 compound 5 Composite Silica gel Triethanolamine 360
catalyst 7 Composite Iron Triethylenetetramine 278 catalyst 8
compound 6 Composite Iron Isopropylamine 32 catalyst 9 compound 2
Composite Iron Aniline 184 catalyst 10 compound 7 Amine compound
Amount of amine compound carried Composite catalyst (percentage
based on Average iron compound or particle BET specific Composite
silica gel) size surface area catalysts (wt, %) (.mu.m) (m.sup.2/g)
Composite 5.0 0.25 78 catalyst 1 Composite 1.0 0.32 51 catalyst 2
Composite 0.1 0.26 101 catalyst 3 Composite 0.02 0.25 84 catalyst 4
Composite 1.0 0.30 70 catalyst 5 Composite 5.0 0.10 10 catalyst 6
Composite 5.0 3.5 210 catalyst 7 Composite 3.0 0.62 29 catalyst 8
Composite 5.0 0.32 48 catalyst 9 Composite 5.0 0.25 40 catalyst 10
Composite catalyst Phosphorus Sulfur Sodium Composite content
content content catalysts (wt. %) (wt. %) (wt. %) Composite 0.002
0.05 0.08 catalyst 1 Composite 0 0.01 0.05 catalyst 2 Composite
0.002 0.01 0.07 catalyst 3 Composite 0.002 0.05 0.08 catalyst 4
Composite 0.49 0.08 0.18 catalyst 5 Composite 0.01 0.17 0.48
catalyst 6 Composite -- -- -- catalyst 7 Composite 0 0.38 0.09
catalyst 8 Composite 0 0.01 0.05 catalyst 9 Composite 0.002 0.05
0.10 catalyst 10 Composite catalyst Catalyst property (Conversion
of chlorobenzene at Composite Apparent density 300.degree. C.)
catalysts (g/ml) (%) Composite 0.43 88 catalyst 1 Composite 0.52 83
catalyst 2 Composite 0.39 79 catalyst 3 Composite 0.44 70 catalyst
4 Composite 0.58 18 catalyst 5 Composite 0.95 11 catalyst 6
Composite -- 10 catalyst 7 Composite 0.49 12 catalyst 8 Composite
0.51 29 catalyst 9 Composite 0.92 21 catalyst 10
[0103]
3 TABLE 3 Examples, Comparative Materials to be treated Examples
and Amount Reference treated Catalyst Examples Kind (g) Kind
Example 2 Ash A 400 Composite catalyst 3 Example 3 Ash B 400
Composite catalyst 2 Example 4 Ash B 400 Composite catalyst 1
Example 5 Ash C 400 Composite catalyst 2 Example 6 Ash C 400
Composite catalyst 4 Example 7 Soil D 400 Composite catalyst 1
Comparative Ash A 400 Composite Example 1 catalyst 5 Comparative
Ash B 400 -- Example 2 Comparative Ash C 400 Composite Example 3
catalyst 6 Comparative Ash C 400 Composite Example 4 catalyst 7
Comparative Ash A 400 Calcium Example 5 hypophosphite Comparative
Ash A 400 Composite Example 6 catalyst 8 Comparative Ash B 400
Composite Example 7 catalyst 9 Comparative Ash C 400 Composite
Example 8 catalyst 10 Reference Ash A 400 Iron compound 1 Example 1
Reference Ash B 400 Iron compound 3 Example 2 Examples, Catalyst
Comparative Amount based Examples and Amount of on 100 wt.
Reference catalyst parts of ash Atmosphere Examples (g) (wt. part)
(flow rate) Example 2 20 5 Air (1 liter/min.) Example 3 40 10
N.sub.2 (inert gas) (10 liter/min.) Example 4 100 25 Air (3
liter/min.) Example 5 20 5 Air (0.1 liter/min.) Example 6 10 2.5
Closed system Example 7 20 5 Air (1 liter/min.) Comparative 20 5
Air Example 1 (3 liter/min.) Comparative 0 0 Air Example 2 (10
liter/min.) Comparative 20 5 Closed system Example 3 Comparative 20
5 Air Example 4 (3 liter/min.) Comparative 40 10 Air Example 5 (3
liter/min.) Comparative 120 30 Air Example 6 (3 liter/min.)
Comparative 20 5 Air Example 7 (1 liter/min.) Comparative 40 10
Closed system Example 8 Reference 20 5 Air Example 1 (3 liter/min.)
Reference 40 10 Closed system Example 2 Examples, Comparative
Examples and Heat-treating Reference temperature Retention time
Examples (.degree. C.) (min.) Example 2 220 150 Example 3 300 60
Example 4 370 30 Example 5 255 180 Example 6 400 30 Example 7 350
60 Comparative 260 180 Example 1 Comparative 385 50 Example 2
Comparative 300 50 Example 3 Comparative 300 120 Example 4
Comparative 300 60 Example 5 Comparative 250 30 Example 6
Comparative 300 60 Example 7 Comparative 350 90 Example 8 Reference
300 60 Example 1 Reference 300 30 Example 2 Examples, Percentage of
dioxin Comparative content after treatment Examples and
Concentration of based on initial dioxin Reference dioxins content
Examples (ng-TEQ/g) (%) Example 2 1.2 17 Example 3 0.014 0.25
Example 4 0.0016 0.028 Example 5 0.65 6.6 Example 6 0.0021 0.021
Example 7 0.0021 8.4 Comparative 9.5 138 Example 1 Comparative 13
228 Example 2 Comparative 17 172 Example 3 Comparative 22 222
Example 4 Comparative 12 174 Example 5 Comparative 7.5 109 Example
6 Comparative 4.1 72 Example 7 Comparative 12.6 127 Example 8
Reference 3.9 57 Example 1 Reference 4.2 74 Example 2
[0104]
4TABLE 4 Fly ash Fly ash Fly ash Samples A B C Concentration
ng-TBQ/g 6.9 5.7 9.9 of dioxins Content of T--Fe (wt. %) 0.4 3.4
1.9 each T--Ca (wt. %) 29.6 27.3 37.5 components T--Pb (wt. %) 0.11
0.05 0.16 T--Zn (wt. %) 0.34 0.41 0.27 T--C (wt. %) 4.05 2.53 3.19
T--S (wt. %) 0.94 0.85 0.73 Concentrations Fe (mg/l) N.D.* N.D.*
N.D.* of respective Ca (wt. %) 4.8 4.6 5.7 components Pb (mg/l)
18.3 2.5 11.4 eluted Zn (mg/l) 5.1 2.0 5.8 Cr.sup.6+ (mg/l) 0.068
0.002 0.009 SO.sub.4 (wt. %) 0.93 1.38 0.78 Se (mg/l) 0.002 0.009
0.019 Cd (mg/l) N.D.* N.D.* N.D.* Hg (mg/l) N.D.* 0.0006 N.D.* As
(mg/l) N.D.* 0.009 N.D.* (Note) *"N.D." means "Not Detected", i.e.,
less than the lower detection limit.
[0105]
5 TABLE 5 Soil Sample D Concentration of ng-TEQ/g 0.025 dioxins
Content of each T--Fe (wt. %) 8.4 components T--Si (wt. %) 21.4
T--Al (wt. %) 11.2 Water (wt. %) 5.1
* * * * *