CA 02766032 2011-12-19
DESCRIPTION
METHOD FOR PRODUCING CARBON MATERIALS
Technical Field
[0001]
The present invention relates to a method for producing a carbon material
which is included in a nonferrous metal reducing agent, a structural carbon
material or a
carbon material for an electric material, and the present invention
particularly relates to
a method for producing a carbon material which is used as an aggregate of an
anode for
aluminum smelting.
Background Art
[0002]
As a main raw material of an anode for aluminum smelting, there is generally
used petroleum coke produced from residues of petroleum refinery processes.
However, the petroleum coke is produced together with transportation fuels
such as
gasoline, so that there is a problem that the supply quantity thereof is
limited or a
problem that impurities such as sulfur contained in crude oil exerts an
adverse effect on
aluminum purity.
[0003]
On the other hand, coal-derived coke used in blast furnace iron-making has
properties close to those of the petroleum coke, and is distributed in more
than enough
quantities in the market as the main raw material of the anode for aluminum
smelting.
However, the coal-derived coke has a problem in quality, because it contains
coal-
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derived ash in an amount of about 10 mass %. Accordingly, it has not been used
for
this purpose.
[0004]
So, in terms of a raw material of a low-ash carbon material, so-called ashless
coal (hyper-coal) is cited (for example, see Patent Document 1), and recently,
the
development thereof has been actively advanced. Here, the ashless coal is
produced
by extracting coal with a solvent, separating only components soluble in this
solvent,
and thereafter removing the solvent. From the structural point of view, the
molecular
weight of this ashless coal widely distributes from a relatively low-molecular-
weight
component having 2 or 3 condensed aromatic rings to a high-molecular-weight
component having about 5 or 6 condensed aromatic rings. Further, ash is
insoluble in
the solvent, so that the ashless coal substantially contains no ash and shows
high fluidity
under heating. This is excellent in thermal fluidity. Of coals, some such as
caking
coal show thermoplastic properties at around 400 C, but the ashless coal
generally melts
at 200 to 300 C (has thermoplasticity), regardless of the grade of a raw
material coal.
So, taking advantage of this property, the application development as binders
for coke
production has been advanced. Further, in recent years, it has been tried to
produce a
carbon material by using this ashless coal as a raw material of the carbon
material.
Prior-Art Documents
Patent Documents
[0005]
Patent Document 1: JP-A-2001-26791
Summary of the Invention
Problem that the Invention is to Solve
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,
[0006]
However, the conventional methods for producing a carbon material have a
problem as shown below.
As described above, the ashless coal is characterized in that it contains no
ash
and has thermoplasticity. It is therefore known that the ashless coal is
effective as a
caking additive for metallurgical coke making. Further, to contain no ash is a
preferred property for an aggregate (main raw material) of an anode for
aluminum
smelting. However, when conversion to carbon (carbonization) in which the
ashless
coal is subjected to a heating treatment to form a carbon material, the
ashless coal
foams. This is an another general property of the ashless coal. This poses a
problem
in the production of the main raw material coke of the anode for aluminum
smelting
(hereinafter appropriately referred to as the anode coke). That is to say,
when the as-
produced ashless coal is carbonized, pores caused by low-molecular-weight
compound
gases (water vapor, CO, CO2, hydrocarbons and the like) formed when
carbonization
remain as such. Accordingly, there is a problem of not forming dense coke
which is
proper as the anode coke. Also, when the ashless coal is used in a nonferrous
metal
reducing agent, a structural carbon material, a carbon material for an
electric material
other than the anode coke, or the like, the same problem is encountered.
[0007]
The invention has been made in view of the above-mentioned problem, and an
object thereof is to provide a method for producing a carbon material, by
which a high
purity carbon material which is dense and has an extremely low ash
concentration can
be economically obtained.
Means for Solving the Problems
[0008]
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,
The present inventors have studied, and then found that atomic ratio of
hydrogen to carbon (hereinafter appropriately referred to as the H/C atomic
ratio) in
ashless coal is preferably adjusted in a predetermined range for using as a
raw material
of an anode coke, a nonferrous metal reducing agent, a structural carbon
material or a
carbon material for an electric material other than the anode coke.
[0009]
In order to adjust the H/C atomic ratio in the ashless coal in the
predetermined
range, specifically, the ashless coal is subjected to a heating treatment.
Such chemical
and physical changes so as to decrease the hydrogen content, such as
decomposition of
an alkyl group, an aromatization reaction, decomposition of an oxygen-
containing
functional group and removal of a low-molecular-weight component, proceed by
the
heating treatment to gradually decrease the H/C atomic ratio. The present
inventors
have found that expansibility of the ashless coal can be suppressed thereby to
result in
being able to suppress foaming when carbonization, thus achieving the
invention.
[0010]
That is to say, a method for producing a carbon material which can be used as
a
nonferrous metal reducing agent, a structural carbon material, a carbon
material for an
electric material or a raw material thereof, according to the invention, is
characterized
by comprising: an ashless coal production step of producing an ashless coal as
a
modified coal by modifying a coal with a solvent; an ashless coal heating step
of
subjecting the above-mentioned ashless coal produced in the above-mentioned
ashless
coal production step to a heating treatment; and a carbonization step of
obtaining a
carbon material by carbonizing the above-mentioned ashless coal which has been
subjected to the heating treatment in the above-mentioned ashless coal heating
step,
wherein an atomic ratio (H/C) of hydrogen to carbon in the above-mentioned
ashless
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'
,
coal which has been subjected to the heating treatment in the above-mentioned
ashless
coal heating step is from 0.6 to 0.67.
[0011]
According to such a production method, the coal is modified in the ashless
coal
production step, thereby producing the ashless coal as the modified coal
having an
extremely low ash concentration. Next, in the ashless coal heating step, this
ashless
coal is subjected to the heating treatment, thereby specifying the H/C atomic
ratio in the
ashless coal to the range of 0.6 to 0.67. Subsequently, in the carbonization
step, this
ashless coal is carbonized, thereby obtaining the carbon material. Then, the
H/C
atomic ratio in the ashless coal after the heating treatment is 0.6 or more,
resulting in
sufficient sintering properties of the ashless coal, and the H/C atomic ratio
is 0.67 or
less, which suppresses expansibility of the ashless coal to suppress foaming
of the
ashless coal when the carbonization treatment, thereby forming the carbon
material
which is dense and has an extremely low ash concentration.
[0012]
Further, in the method for producing a carbon material according to the
invention, it is preferred that the above-mentioned heating treatment of the
ashless coal
in the above-mentioned ashless coal heating step is performed under the
presence of the
same solvent as used for the modification of the above-mentioned coal in the
above-
mentioned ashless coal production step.
[0013]
According to such a production method, use of the solvent increases the
efficiency of heat transfer to make heating of the ashless coal uniform.
Further, the
same solvent as used for the modification of the coal is used, so that
economic
efficiency is improved.
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Advantages of the Invention
[0014]
According to the method for producing a carbon material of the invention, the
carbon material which is dense and has an extremely low ash concentration can
be
obtained. Further, such a carbon material can be economically obtained.
Brief Description of Drawing
[0015]
[Fig. 1] Fig. 1 is a graph indicating the relationship between the strength
and
the H/C atom number ratio in Examples and Comparative Examples of the
invention.
Embodiment for Carrying Out the Invention
[0016]
The method for producing a carbon material according to the invention will be
described below.
The method for producing a carbon material according to the invention
comprises an ashless coal production step, an ashless coal heating step and a
carbonization step. The respective steps will be described below.
[0017]
<Ashless Coal Production Step>
The ashless coal production step is a step of producing an ashless a coal as a
modified coal by modifying a coal with a solvent.
The ashless coal said in the invention is so-called hyper-coal, and is
produced
by subjecting the coal to solvent extraction to remove ash and insoluble coal
components. This ashless coal has an extremely small ash content (ash
concentration:
1.0 mass % or less) and a water content of about 0.5 mass % or less.
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[0018]
As a method for obtaining the ashless coal, a known method is utilizable, and
the kind of solvent and production conditions are appropriately selected in
view of
properties of the coal and design of the carbon material as a raw material. As
a typical
method, there is a method of heating a mixture of a solvent having high
solubilization
ability to the coal, which is an aromatic solvent (hydrogen-donating or non-
hydrogen-
donating solvent) in many cases, and the coal to extract organic components in
the coal.
However, in order to obtain the ashless coal more efficiently and
inexpensively, it is
preferred to produce the ashless coal, for example, by the following method.
In that
method, first, a mixture (slurry) of the coal and the non-hydrogen-donating
solvent is
heated, thereby extracting coal components soluble in the non-hydrogen-
donating
solvent. Next, the slurry after extraction is separated into a liquid part and
a non-liquid
part, and the above-mentioned non-hydrogen-donating solvent is separated from
the
above-mentioned liquid part, thereby producing the ashless coal.
[0019]
As the coal of the raw material of the ashless coal (hereinafter also referred
to
as the raw material coal), it is preferred to use low rank coal. Use of
inexpensive low
rank coal makes it possible to produce the ashless coal more inexpensively, so
that
economic efficiency can be further improved. However, the coal used is not
limited to
the low rank coal, and bituminous coal may be used as needed.
[0020]
Here, as the low rank coal, there is coal such as non-slightly-caking coal,
steam
coal or low-rank coal (brown coal, subbituminous coal or the like). As the low-
rank
coal, there is, for example, brown coal, lignite, subbituminous coal or the
like.
Further, for example, as the brown coal, there is Victorian coal, North Dakota
coal,
Berga coal or the like, and as the subbituminous coal, there is West Banco
coal,
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Binungan coal, Samarangau coal or the like. The low-rank coal is not limited
to ones
exemplified above. Any coal which contains a large amount of water and is
required to
be dehydrated is included in the low-rank coal called in the present
invention. It is
preferred to previously pulverize the coal into fine grains as small as
possible, and the
grain size is preferably 1 mm or less.
[0021]
The non-hydrogen-donating solvent is a coal derivative as a solvent which is
mainly purified from distillation products of coal and mainly composed of
bicyclic
aromatic compounds. This non-hydrogen-donating solvent is stable even in a
heated
state, and excellent in affinity with the coal. For this reason, when the non-
hydrogen-
donating solvent is used, the rate of soluble components (coal components
herein)
extracted in the solvent (hereinafter also referred to as the extraction rate)
is increased,
and the solvent can be easily recovered by a method such as distillation.
Typical
components of the non-hydrogen-donating solvent include naphthalene,
methylnaphthalene, dimethylnaphthalene, trimethylnaphthalene and the like as
the
bicyclic aromatic compounds. In addition, naphthalenes, anthracenes and
fluorenes,
which have aliphatic side chains, and alkylbenzenes in which biphenyls or long-
chain
aliphatic side chains are added thereto are contained in components of the non-
hydrogen-donating solvent.
[0022]
The extraction rate of the coal achieved by the high temperature extraction
using the non-hydrogen-donating solvent is generally high. Further, the non-
hydrogen-donating solvent is easy to be cyclically used, because it is easily
recoverable,
different from a polar solvent. Further, it is unnecessary to use expensive
hydrogen,
catalyst and the like, so that the ashless coal is obtained by solubilizing
the coal at a low
cost, thereby being able to improve economic efficiency.
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[0023]
The coal concentration based on the solvent is preferably in a range of 10 to
50
mass %, and more preferably in a range of 20 to 35 mass %, on a dry coal
basis,
although it depends on the kind of raw material coal. When the coal
concentration
based on the solvent is less than 10 mass %, the ratio of the coal components
extracted
in the solvent to the amount of the solvent decreases. This is therefore not
economical.
On the other hand, the higher coal concentration is better. However, when the
coal
concentration exceeds 50 mass %, the viscosity of the slurry prepared is
increased.
Accordingly, it is liable to become difficult to handle the slurry or to
separate a liquid
part from a non-liquid part (described later).
[0024]
The extraction temperature of the slurry is preferably within a range of 300
to
450 C. When the extraction temperature is within this range, bonds between
molecules which constitute the coal are loosened to cause mild pyrolysis,
resulting in
the highest extraction rate. When the extraction temperature is less than 300
C, it is
liable to becomes insufficient for weakening the bonds between the molecules
which
constitute the coal, and it is difficult to improve the extraction rate. On
the other hand,
when the extraction temperature exceeds 450 C, the pyrolytic reaction of the
coal
becomes very active to cause recombination of pyrolytic radicals formed.
Accordingly, it is difficult to improve the extraction rate, and modification
of the coal
becomes difficult to occur. The heating temperature is preferably from 300 to
400 C.
[0025]
A criterion of the heating time (extraction time) is a time until reaching
dissolution equilibrium, but realization thereof is economically
disadvantageous.
Accordingly, the heating time is usually from about 10 to 60 minutes, although
it cannot
be said without reservation because it varies depending on conditions such as
the grain
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size of the coal and the kind of solvent. When the heating time is less than
10 minutes,
the extraction of the coal components is liable to become insufficient. On the
other
hand, even when the heating time exceeds 60 minutes, the extraction proceeds
no
further. This is therefore not economical.
[0026]
The extraction of the coal components soluble in the non-hydrogen-donating
solvent is preferably performed under the presence of an inert gas. The
reasons for this
are that contact with oxygen is dangerous because there is a possibility of
catching fire,
and that use of hydrogen causes an increase in cost.
The inert gas used is preferably inexpensive nitrogen, but is not particularly
limited thereto. Further, the pressure is preferably from 1.0 to 2.0 MPa,
although it
depends on the temperature in the extraction or the vapor pressure of the
solvent used.
When the pressure is lower than the vapor pressure of the solvent, the solvent
is
volatilized and not kept in a liquid phase, resulting in impossibility of the
extraction.
In order to keep the solvent in the liquid phase, a pressure higher than the
vapor
pressure of the solvent is required. On the other hand, when the pressure is
too high,
an instrument cost and an operation cost are increased. This is therefore not
economical.
[0027]
After the coal components have been extracted as described above, the slurry
is
separated into the liquid part and the non-liquid part. Here, the liquid part
is a solution
containing the coal components extracted in the solvent, and the non-liquid
part is a
solute containing coal components (ash-containing coal, namely ash coal)
insoluble in
the solvent.
[0028]
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As methods for separating the slurry into the liquid part and the non-liquid
part,
various filtration methods and centrifugation methods are generally known.
However,
in the methods by filtration, frequent replacement of filters is necessary.
Further, in
the methods by centrifugation, blocking caused by undissolved coal components
is
liable to occur. It is therefore difficult to industrially perform these
methods.
Accordingly, it is preferred to use a gravity settling method which can
continuously
operate a fluid and is also suitable for bulk handling at a low cost. The
liquid part
(hereinafter also referred to as the supernatant liquid) as a solution
containing the coal
components extracted in the solvent is obtained thereby from an upper part of
a gravity
settling tank. Further, from a lower part of the gravity settling tank, the
non-liquid part
(hereinafter also referred to as the solid concentrated liquid) as a solvent
containing the
coal components insoluble in the solvent is obtained.
[0029]
Then, the ashless coal is obtained by separating the non-hydrogen-donating
solvent from this liquid part.
As methods for separating the solvent from the supernatant liquid (liquid
part),
there can be used common distillation methods, evaporation methods (such as
spray dry
methods) and the like. From the supernatant liquid, the ashless coal
containing
substantially no ash is obtained. This ashless coal has an ash content of 1.0
mass % or
less, and scarcely contains ash. Further, this ashless coal has a water
content of
approximately 0.5 mass % or less, and shows a calorific value higher than that
of the
raw material coal. Accordingly, the high purity carbon material having an
extremely
low ash concentration can be obtained by carbonizing this ashless coal.
[0030]
<Ashless Coal Heating Step>
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The ashless coal heating step is a step of subjecting the ashless coal
produced
in the above-mentioned ashless coal production step to a heating treatment.
The as-produced ashless coal shows extremely high volumetric expansion.
Accordingly, in order to suppress expansion, the heating treatment is
performed. It is
necessary to perform the heating treatment so that the atomic ratio (H/C) of
hydrogen to
carbon in the ashless coal after the heating treatment is adjusted to a range
of 0.6 to
0.67.
[0031]
Here, the H/C atomic ratio of the as-produced ashless coal which is subjected
to no treatment is in a range of approximately 0.7 to 1.0, although it varies
depending on
the kind of raw material coal or production conditions of the ashless coal.
However,
when the heating treatment is performed to this ashless coal, chemical and
physical
changes so as to decrease the hydrogen content, such as decomposition of an
alkyl
group, an aromatization reaction, decomposition of an oxygen-containing
functional
group and removal of a low-molecular-weight component, proceed to gradually
decrease the H/C atomic ratio. Then, the H/C atomic ratio is adjusted to a
range of 0.6
to 0.67 by the heating treatment.
[0032]
That the H/C atomic ratio is smaller than 0.6 means that the heating treatment
is excessive. When the heating treatment is excessive, sintering properties
become
insufficient to obtain only a powdery carbon material, even though this
ashless coal is
carbonized. For this reason, when the H/C atomic ratio is less than 0.6, the
carbon
material used as the raw material of the anode coke cannot be obtained. On the
other
hand, that the H/C atomic ratio is larger than 0.67 shows that the heating
treatment is
insufficient, and a relatively large amount of hydrogen is contained in the
ashless coal.
For this reason, when the H/C atomic ratio exceeds 0.67, the ashless coal
foams during
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the carbonization in the carbonization step. Thus, foaming of the ashless coal
during
the carbonization can be suppressed while leaving proper sintering properties
by
adjusting the H/C atomic ratio to a range of 0.6 to 0.67 by the heating
treatment of the
ashless coal.
[0033]
A method of the heating treatment of the ashless coal is not particularly
limited, and it can be performed by a known method. For example, the ashless
coal is
heated at 350 to 500 C, preferably at 380 to 460 C, in vacuum, under high
pressure or
in an inert atmosphere. The treating time required is roughly from 10 minutes
to 5
hours, although it varies depending on properties of the ashless coal or the
treating
temperature. Thus, the H/C atomic ratio is regulated to a range of 0.6 to 0.67
by taking
into consideration the properties of the ashless coal, and appropriately
adjusting the
treating temperature and the treating time.
[0034]
Further, the heating treatment of the ashless coal is preferably performed
under
the presence of the same solvent as used for the modification of the coal in
the ashless
coal production step.
That is to say, the ashless coal is mixed with the solvent so as to form a
slurry
form, and thereafter subjected to the heating treatment. The amount of the
solvent
based on the ashless coal is not particularly limited. However, from the
viewpoint of
obtaining the slurry having a proper viscosity, the ashless coal concentration
based on
the solvent is, for example, in a range of 10 to 50 mol %, and preferably in a
range of 20
to 35 mol %, on a dry coal basis. Further, the heating treatment of the
ashless coal as
said herein may be performed without separating the solvent, by heating the
liquid part
as the coal components extracted in the above-mentioned solvent, as it is. As
methods
for separating the solvent from the ashless coal after the heating treatment,
there can be
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used common distillation methods, evaporation methods (such as spray dry
methods)
and the like.
[0035]
By using the solvent, the efficiency of heat transfer is increased more than
the
case of heating the ashless coal as it is, and uniform heating becomes
possible.
Further, use of the same solvent as used for the modification of the coal can
reduce a
production cost. The solvents used for the heating treatment of the ashless
coal
include alkylnaphthalenes, anthracene oil and the like as suitable ones.
[0036]
<Carbonization Step>
The carbonization step is a step of obtaining a carbon material by carbonizing
the ashless coal which has been subjected to the heating treatment in the
above-
mentioned ashless coal heating step. The ashless coal is carbonized by this
carbonization step to obtain the carbon material.
[0037]
A method and conditions of the carbonization treatment are not particularly
limited, and a known technique can be used. Typically, the ashless coal is
baked in an
inert gas atmosphere such as nitrogen or argon at about 1,000 C to be
subjected to the
heating treatment, thereby converting the ashless coal to carbon. Further, of
the rising
temperature rate may be about 0.1 to 5 C/min. This carbonization treatment may
be
performed under pressure using a hot isostatic pressing apparatus or the like.
Furthermore, a binder component such as asphalt pitch or tar may be added as
needed.
In addition, after the ashless coal which has been subjected to the heating
treatment is
appropriately formed, the carbonization step may be performed. There is no
particular
limitation also on the form of a carbonization furnace, and a known one can be
used.
Examples thereof include a pot furnace, a lead hammer furnace, a kiln, a
rotary kiln, a
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shaft furnace, a chamber furnace and the like. However, the carbonization
furnace is
not limited thereto, and another one may be used.
[0038]
Then, the carbon material obtained by the production method of the invention
can be suitably used as the main raw material coke of the anode for aluminum
smelting.
Further, in addition to this, the carbon material obtained by the production
method of
the invention can also be used as the nonferrous metal reducing agent, the
structural
carbon material or the carbon material for an electric material other than the
anode for
aluminum smelting, or can also be used as a raw material of the nonferrous
metal
reducing agent, the structural carbon material or the carbon material for an
electric
material. Here, the nonferrous metal reducing agent is a reducing agent used
for
reduction of a nonferrous metal such as silicon or titanium. Further, the
structural
carbon material is, for example, a carbon material used as a raw material of a
structural
material made of carbon such as a carbon heat insulator or a crucible.
Furthermore,
the carbon material for an electric material is a carbon material used as a
raw material of
an electric material made of carbon such as a carbon electrode, as well as the
anode for
aluminum smelting. The description of being used as a raw material thereof is
described, for example, because it is necessary to perform a secondary
treatment such as
heat treatment to the carbon material in some cases.
[0039]
As described above, the method for producing a carbon material of the
invention comprises the ashless coal production step, the ashless coal heating
step and
the carbonization step. However, in carrying out the invention, another step
such as a
coal pulverization step for pulverizing the raw material coal, a removal step
for
removing unwanted matter such as refuse or a ashless coal drying step for
drying the
ashless coal may be contained between or before or after the above-mentioned
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,
respective steps, within a range not exerting an adverse effect on the above-
mentioned
respective steps.
Examples
[0040]
The method for producing a carbon material according to the invention will be
specifically described below with respect to examples and comparative
examples.
[Production of Ashless Coal]
First, ashless coal was produced by the following method.
A raw material coal is a raw material coal for coke production (coal A) as
bituminous coal or a steam coal for thermal power generation (coal B) as
bituminous
coal. A solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical
Co.,
Ltd.)) is mixed in an amount (20 kg) four times larger than that (5 kg) of
this raw
material coal, thereby preparing a slurry. This slurry was pressurized with
nitrogen of
1.2 MPa, followed by extracting in an autoclave with an internal volume of 30
L under
conditions of 370 C and 1 hour. This slurry was separated into a supernatant
liquid
and a solid concentrated liquid in a gravity settling tank maintained at the
same
temperature and pressure, and the solvent was separated and recovered from the
supernatant liquid by a distillation method to obtain the ashless coal.
[0041]
[Heating Treatment]
Then, the ashless coal is subjected to a heating treatment by the following
method.
The heating treatment of the ashless coal is performed under conditions of
using 1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.) as
a
solvent in an amount three times (three times by mass) that of the ashless
coal, or under
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' =
conditions of using no solvent at all. The heating treatment was performed by
rising
the temperature to a predetermined temperature shown in Table 1 at 10 C/min
while
stirring the ashless coal in an airtight autoclave having an initial nitrogen
pressure of 0.1
MPa, and keeping it for a predetermined period of time shown in Table 1. After
the
treatment, the gas in the autoclave was discharged, and heating was performed
under a
pressure of 0.001 MPa at 150 C for 1 hour, thereby removing by distillation
the solvent
and oil components which were possibly generated. Thereafter, the ashless coal
which
had been subjected to the heating treatment was recovered. Then, the H/C
atomic ratio
is determined by elemental analysis thereof.
[0042]
[Carbonization Treatment]
Next, the ashless coal is subjected to a carbonization treatment by the
following method.
5 g of the ashless coal which had been subjected to the heating treatment and
pulverized to 1 mm or less was filled in a quartz test tube having an internal
diameter of
mm so as to obtain a bulk density of 0.8 g/cc. Thereafter, in the nitrogen
atmosphere, the temperature was rised to 1,000 C at 3 C/min and kept at this
temperature for 30 minutes to perform carbonization, thereby obtaining a
carbon
material.
20 [0043]
The carbon material was cut to a length of 10 mm, a crushing test was
performed to measure the strength. The crushing test is performed by placing a
sample
on a lower pressure plate, compressing the sample with an upper pressure
element, and
measuring the strength (crushing strength) at the time when the sample breaks.
Then,
the sample having a strength of 5.0 MPa or more is judged as a dense carbon
material.
However, the strength also varies depending on the conditions of the
carbonization
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6 1
treatment (the bulk density of the raw material, whether formed or not formed,
or the
heat treatment temperature), so that this value is just a relatively
comparative value.
The carbon material having a higher strength is denser, and suitable as the
raw material
of the anode coke.
[0044]
Table 1 shows the results of this test. In Table 1, the values not satisfying
the
range of the invention are indicated as underlined. Further, 1-
methylnaphthalene is
denoted as MN in the table. Further, Fig. 1 shows a graph indicating the
relationship
between the strength and the H/C atomic ratio. The strength "0.00" indicates
that the
strength could not be measured because of lack of a measurable strength.
[0045]
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[Table 1]
Raw Treating Treating
H/C Strength
No. Material Solvent Temperature Time
Atomic ratio (MPa)
Coal ( C) (min)
1 A MN 440 60 0.61 8.30
2 A MN 440 90 0.62 6.40
3 A MN 460 30 0.64 12.20
4 A MN 440 120 0.58 4.80
A MN 480 30 0.57 1.70
6 A MN 480 120 0.50 0.00
7 A MN 480 0 0.73 0.00
8 A Not used 460 90 0.68 0.00
9 A Not used 420 60 0.74 0.00
A Not used 440 60 0.72 0.00
11 A Not used 460 60 0.70 0.00
12 A Not used 420 90 0.75 0.00
13 A Not used 440 90 0.71 0.00
14 B MN 440 30 0.62 5.90
B MN 430 60 0.64 7.40
16 B MN 440 45 0.65 8.80
17 B MN 440 60 0.64 8.00
18 B MN 450 _ 30 0.64 11.90
19 B MN 460 15 0.65 9.10
B MN 460 30 0.63 11.40
21 B MN 440 60 0.58 1.30
22 B MN 460 30 0.57 0.50
23 B MN 430 _ 30 0.73 0.00
24 B MN 420 60 0.72 0.00
B MN 460 10 0.70 0.00
[0046]
As shown in Table 1 and Fig. 1, Nos. 1 to 3 and 14 to 20 satisfy the range of
5 the invention. These were therefore carbonized without forming in the
carbonization
step to form the dense carbon materials, and the strength thereof was high.
[0047]
19
CA 02766032 2013-01-07
- = = -
On the other hand, Nos. 4 to 6, 21 and 22 have a H/C atomic ratio of less than
the lower limit value. The carbon materials therefore became powdery to fail
to form
the dense carbon materials, and the strength thereof was low. The strength in
No. 6
could not be measured.
Further, Nos. 7 to 13 and 23 to 25 have a H/C atomic ratio exceeding the upper
limit value. The ashless coal was therefore foamed in the carbonization step,
and thus,
the dense carbon materials could not be obtained, and the strength thereof
could not be
measured.
[0048]
The method for producing a carbon material according to the invention has
been described above in detail showing the embodiments and examples. However,
the
gist of the invention is not limited to the contents described above, and the
scope of
right thereof should be broadly interpreted based on the description of the
claims. It
goes without saying that the contents of the invention can be widely modified,
changed,
