JP5342794B2 - Carbon material manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inexpensive carbonaceous raw material with a low ash content and excellent self-sintering properties, a method for manufacturing a high strength coke, and the high strength coke. <P>SOLUTION: The method for manufacturing the carbonaceous raw material comprises a slurry heating step for executing a heat treatment of a slurry comprising coal and an aromatic solvent, a separating step for separating the heat-treated slurry into a liquid component with the coal dissolved and a solid component comprising an ash content and insoluble coal, an ashless coal obtaining step for obtaining ashless coal by removing the aromatic solvent from the liquid component, and an ashless coal heating step for applying a heat treatment to the ashless coal so as to obtain the carbonaceous raw material. The volatile content of the carbonaceous raw material measured by the method defined in JIS M 8812 is 24 mass% or more and less than 35 mass%. The method for manufacturing the coke differs from the method for manufacturing the carbonaceous raw material in that the ashless coal heating step is substituted by a dry distillation step. The coke does not contain carbon derived from inertinite in a maceral group of raw material coal for coke production. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  A method for producing a carbon raw material used as a raw material for a carbon material constituting a structural material or an electric material, a method for producing a coke intermediately produced by the carbon raw material produced by this method, and a strength used for metallurgy. It is about high coke.

  Conventionally, carbon materials have been widely used as structural materials and electrical materials because of their excellent heat resistance and chemical stability and electrical conductivity. Further, since carbon exhibits an action of reducing many metal oxides at a high temperature, it is also used as a reducing agent in refining silicon and titanium. The characteristics required for carbon materials vary depending on the application, but it goes without saying that impurities other than carbon (called ash) are not so good. It is a source of contamination. This is especially true when used as a metallurgical reducing agent.

  Now, in the production process of carbon materials, usually, aggregate components such as coke (carbon content is high and carbonizes without melting) and binder components (there is thermoplasticity, and aggregates are bonded together, Carbonized) is mixed and molded, and is carbonized by heat treatment at a high temperature.

  As another method for producing a carbon material, there is a method using a self-sintering carbon raw material. Self-sintering is a property that allows molding without adding a binder component and carbonizes it while maintaining its shape by heat treatment.

  Typical examples of the self-sintering carbon raw material include raw coke (coke produced by dry distillation at around 600 ° C.) and mesocarbon microbeads.

  Raw coke is produced by heat-treating coal tar, coal pitch, or various petroleum refined residue oils. Since the raw material contains ash, it is difficult to convert it into a low ash self-sintering carbon raw material.

  Similarly, mesocarbon microbeads are also carefully treated with coal tar, coal pitch, or various petroleum refining residues to produce microspheres (mesocarbon microbeads) with optical anisotropy, which are separated. (For example, refer to Patent Document 1).

  On the other hand, there can be mentioned so-called ashless coal, which has been actively developed recently from the viewpoint of a low ash carbonaceous material (see, for example, Patent Document 2). Here, ashless coal is produced by extracting coal with a solvent, separating only the components soluble in the solvent, and then removing the solvent. Since ash is not soluble in the solvent, ashless coal is substantially free of ash. This is the first feature of ashless coal. The second feature of ashless coal is that it has excellent thermal fluidity. Some coals exhibit thermoplasticity at around 400 ° C. like caking coal, but ashless coal melts at 200-300 ° C. regardless of the quality of the raw coal.

The conventional carbon raw material production method has the following problems. The mesocarbon microbeads described in Patent Document 1 can increase the purity to some extent and reduce the ash concentration in the separation step. However, the manufacturing method described in Patent Document 1 is not necessarily a manufacturing method that can easily manufacture a self-sintering carbon raw material called mesocarbon microbeads for the following reason.
(1) In order to produce mesocarbon microbeads, a long and highly controlled heat treatment is required.
(2) The yield of mesocarbon microbeads is not so high.
(3) A complicated operation is required for separating mesocarbon microbeads.

  In addition, the ashless coal described in Patent Document 2 is disadvantageous in terms of heat fluidity (meltability), which is one of its features, as a self-sintering carbon raw material. In other words, when manufacturing a structural material or an electric material (carbon material), even if the molded body can be molded from ashless coal, the molded body is melted in the heat treatment process for carbonization. Since the shape is lost, a carbon material having a desired shape cannot be obtained. Therefore, the ashless coal described in Patent Document 2 has a problem that it is inferior in self-sinterability as a carbon material.

  By the way, coke is generally produced by dry distillation of coal, and its strength is desired to be high. That is, in metallurgy, for example, iron making by the blast furnace method, coke is introduced into a large-volume blast furnace together with a large amount of iron ore, and coke is involved in the reduction reaction while blowing air from the lower part of the furnace. Therefore, a high strength that does not deteriorate the flow of the air blown and damaged is required. In order to meet this demand, high-quality coal having high caking properties is particularly preferably used as a raw coal for producing coke.

  Good quality coal is suitable as a raw material for producing high-strength coke, but because of its depletion and expensiveness, research and development to produce high-strength coke while using low-cost coal, although its quality is low Has been performed conventionally. In order to produce high-strength coke, it is indispensable to understand the coking reaction based on the maceral group, which is a group of microstructural components recognized when microscopically observing coal. As a result of conventional research and development, it is known that there is an appropriate range for the ratio of inertinite (inactive component) in coal, and that the bond strength between inertinite coke and active component-derived coke is important. .

Research and development has been conducted to produce high-strength coke with a focus on the coal density in the coke oven and the moisture content of the coal in the blending of multiple types of coal. However, it is difficult to stably produce coke having a strength index DI ⁶⁰⁰ _9.5 of 88.0 or more, which is an index of coke strength. For example, if the coal filling density in the coke oven is increased, high strength coke can be obtained, but if the density is increased to 780 kg / m ³ or more, the pressure in the coke oven may damage the furnace. I want to avoid the use of new coke production methods. In addition, extremely low moisture causes a cost for that purpose. For this reason, the limit of the strength index DI ⁶⁰⁰ _9.5 of coke obtained by a method using a coke production raw coke and using a coke oven is considered to be about 86.0 to 87.0.
JP 2007-186386 A JP 2001-26791 A

  In view of the above circumstances, an object of the present invention is to provide a carbon raw material production method that can produce a carbon raw material that has a low ash content and has excellent self-sintering properties, and that can be carried out at a low cost. .

  Another object of the present invention is to provide a coke production method for realizing high-strength coke and a high-strength coke.

  The method for producing a carbon raw material according to the present invention includes a slurry heating step of heat-treating a slurry containing coal and an aromatic solvent, a liquid component in which coal is dissolved, and an ash content of the slurry heat-treated in the slurry heating step. Obtained by the ashless coal heating step, including a separation step of separating into a solid component made of insoluble coal, and an ashless coal acquisition step of removing the aromatic solvent from the liquid component to acquire ashless coal When measured by the method defined in JIS M 8812, the volatile content of the carbon raw material is less than 35% by mass and 24% by mass or more.

  According to the above procedure, the carbon raw material production method includes a slurry heating step, a separation step, and an ashless coal acquisition step, so that ashless coal having an extremely low ash concentration can be obtained. The ash concentration of the carbon raw material made from the above also decreases. Moreover, the volatile matter of the carbon raw material which consists of ashless coal is prepared in the predetermined range by including the ashless coal heating process which heat-processes ashless coal, and the self-sintering property of a carbon raw material improves. Then, ashless coal is obtained by a simple method of heat treatment (heat extraction) of the slurry, separation of the liquid component in which the coal component is dissolved, and removal of the aromatic solvent from the separated liquid component. Moreover, the self-sinterability which was the fault of the conventional ashless coal improves only by performing the simple method of heat-treating ashless coal.

  The method for producing a carbon raw material according to the present invention is characterized in that in the separation step, the liquid component and the solid component are separated by a gravity sedimentation method. According to the above procedure, the separation operation can be continuously performed by separating the liquid component and the solid component by the gravity sedimentation method.

  The method for producing a carbon raw material according to the present invention is characterized in that, in the ashless coal acquisition step, the aromatic solvent is removed from the liquid component by a distillation method or an evaporation method. According to the above procedure, the removal of the aromatic solvent from the liquid component is performed by the distillation method or the evaporation method, thereby simplifying the operation of removing the aromatic solvent.

  The method for producing coke according to the present invention includes a slurry heating step in which a slurry containing coal and an aromatic solvent is heat-treated, a slurry that has been heat-treated in the slurry heating step, a liquid component in which coal is dissolved, an ash content, and an insoluble matter. Separation step for separating into solid components made of coal, ashless coal acquisition step for removing ash coal by removing aromatic solvent from the liquid component, and ashless coal acquired in the ashless coal acquisition step And a carbonization step of carbonizing.

  In the method for producing coke according to the present invention, in order to suppress excessive expansion of ashless coal in the dry distillation step and to achieve higher strength coke, it is obtained in the ashless coal acquisition step before the dry distillation step. It is preferable to provide a pretreatment step for reducing the expansion of the ashless coal.

The coke according to the present invention is characterized by not containing carbon derived from inertite in the maceral group of coking coal. The strength index DI ⁶⁰⁰ _9.5 of the coke can be 88.0 or more, and the coke according to the present invention is suitable for use in metallurgy such as iron making, and is used in a method for producing pig iron.

  According to the method for producing a carbon raw material according to the present invention, low ash is obtained by including a slurry heating step, a separation step, an ashless coal acquisition step, and an ashless coal heating step of adjusting the volatile content to a predetermined range. Thus, a carbon material having excellent self-sinterability can be produced. Moreover, such a carbon raw material can be easily manufactured.

Since carbon materials have excellent self-sintering properties, when carbon materials are produced using these carbon materials, they can be easily formed into a desired shape without using a binder, and carbonized as it is. Can be made. Accordingly, the produced carbon material can be used as a structural material, an electrical material, or a metallurgical reducing agent.

  Moreover, according to the manufacturing method of the carbon raw material which concerns on this invention, a carbon raw material can be manufactured in large quantities at low cost by performing a separation process by a gravity sedimentation method.

  Furthermore, according to the method for producing a carbon raw material according to the present invention, the carbon raw material can be more easily produced by removing the aromatic solvent in the ashless coal acquisition step by a distillation method or an evaporation method.

  In the coke production method according to the present invention, ashless coal substantially free of inert knit, which has been thought to be appropriate in the past, is dry-distilled, so that high strength coke can be obtained.

  The coke according to the present invention does not contain carbon derived from the inert knit, which is this characteristic, and thus has high strength.

  Next, the manufacturing method of the carbon raw material which concerns on this invention with reference to drawings is demonstrated in detail. In the drawings to be referred to, FIG. 1 is a flowchart for explaining steps of a carbon raw material production method, and FIG. 2 is a schematic diagram showing a solid-liquid separation device for performing a gravity sedimentation method.

<< Method for producing carbon raw materials >>
As shown in FIG. 1, the method for producing a carbon raw material includes a slurry heating step (S1), a separation step (S2), an ashless coal acquisition step (S3), and an ashless coal heating step (S4). Is included.
Hereinafter, each step will be described.

<Slurry heating step (S1)>
The slurry heating step (S1) is a step of preparing a slurry by mixing coal and an aromatic solvent, and heating the slurry containing the coal and the aromatic solvent. And a coal component is heat-extracted by the aromatic solvent by heat-processing a slurry.

  Coal used as a raw material (hereinafter also referred to as “raw coal”) may be non-minor cohesive that has almost no softening and melting properties, or low quality coal such as steam coal, low-grade coal lignite, sub-bituminous coal, etc. preferable. By using inexpensive coal such as these, ashless coal can be produced at a lower cost, so that economic efficiency can be further improved. However, the coal used is not limited to these inferior coals, and bituminous coals may be used.

  In addition, inferior coal here means coals, such as a non-slightly caking coal, a general coal, and a low grade coal. Further, the low-grade coal is coal that contains 20% or more moisture and is desired to be dehydrated. Examples of such low-grade coal include lignite, lignite, and sub-bituminous coal. For example, lignite coal includes Victoria coal, North Dagota coal, Berga coal, and sub-bituminous coal includes West Bagon coal, Binungan coal, Samarangau coal, and the like. The low-grade coal is not limited to those exemplified above, and any coal containing a large amount of water and desired to be dehydrated is included in the low-grade coal referred to in the present invention.

  Generally, aromatic solvents that dissolve coal include monocyclic aromatic compounds such as benzene, toluene, and xylene, and bicyclic aromatic compounds such as naphthalene, methylnaphthalene, dimethylnaphthalene, and trimethylnaphthalene. . The bicyclic aromatic compound includes other naphthalenes having an aliphatic side chain, and biphenyl and alkylbenzene having a long aliphatic side chain. A bicyclic aromatic compound which is a non-hydrogen donating solvent is preferable.

  The non-hydrogen donating solvent is a coal derivative which is a solvent mainly composed of a bicyclic aromatic and purified mainly from a coal carbonization product. Since this non-hydrogen donating solvent is stable even in a heated state and has excellent affinity with coal, the proportion of coal components extracted into the solvent (hereinafter also referred to as “extraction rate”) is high. It is a solvent that can be easily recovered by methods such as distillation. The recovered solvent can be recycled for improving economic efficiency.

  The aromatic solvent preferably has a boiling point of 180 to 330 ° C. When the boiling point is less than 180 ° C., the required pressure in the heat extraction or in the separation step (S2) described later increases, and the loss due to volatilization increases in the step of recovering the aromatic solvent. Solvent recovery is reduced. Furthermore, the extraction rate in the heat extraction decreases. On the other hand, when it exceeds 330 ° C., it becomes difficult to separate the aromatic solvent from the liquid component or the solid component in the separation step (S2), and the solvent recovery rate decreases.

  Although the coal density | concentration with respect to an aromatic solvent is based also on the kind of raw material coal, the range of 10-50 mass% is preferable on a dry coal basis, and the range of 20-35 mass% is more preferable. When the coal concentration with respect to the aromatic solvent is less than 10% by mass, the proportion of the coal component extracted into the aromatic solvent is less than the amount of the aromatic solvent, which is not economical. On the other hand, the higher the coal concentration, the better. However, when it exceeds 50% by mass, the viscosity of the slurry becomes high, and it becomes difficult to move the slurry and separate the liquid component and the solid component in the separation step (S2).

  In the heat treatment (heat extraction) of the slurry, it is preferable that the slurry is extracted at a temperature of 400 to 420 ° C. (the lower limit temperature may be 370 ° C.) for 20 minutes or less and then cooled to 370 ° C. or less.

  When the heating temperature of the slurry is less than 370 ° C., it is insufficient to weaken the bonds between the molecules constituting the coal. When inferior coal is used as the raw coal, in the ashless coal acquisition step (S3) described later The resolidification temperature of the obtained ashless coal cannot be increased. On the other hand, if it exceeds 420 ° C., the pyrolysis reaction of coal becomes very active, and recombination of the generated pyrolysis radical occurs, so that the extraction rate decreases.

  When the heating temperature is in the range of 400 to 420 ° C. (the lower limit temperature may be 370 ° C.), there is no problem for a short time of several minutes to 20 minutes. However, as the extraction time becomes longer, the thermal decomposition reaction proceeds too much and radicals The polymerization reaction proceeds and the extraction rate decreases. However, a relatively high extraction rate is maintained for an extraction time of 20 minutes or less. Further, at a temperature of 370 ° C., the extraction rate becomes maximum when the extraction time is 30 minutes or more, and the extraction rate does not change greatly even after the extraction time of several hours thereafter. Regardless of whether the extraction is performed at two stages of temperature, in order to improve the extraction rate, it is most preferable to heat at 370 to 420 ° C. for 20 minutes or less and then cool to 370 ° C. or less. It is.

  The lower limit of the temperature for cooling is preferably 350 ° C. When the temperature is lower than 350 ° C., the dissolving power of the aromatic solvent is reduced, and re-precipitation of the extracted coal component occurs, so that the yield of ashless coal is reduced.

  In the heat extraction, as described later, for example, the extraction tank may be raised to 400 to 420 ° C. (the lower limit temperature may be 370 ° C.) and immediately cooled, and the lower limit of the extraction time cannot be determined unconditionally. However, from the viewpoint of operation of the extraction tank, the lower limit of the extraction time is preferably set to 1 minute. That is, in this case, the extraction time is preferably in the range of 1 to 20 minutes.

And after heating for 20 minutes or less at the temperature of 400-420 degreeC (a minimum temperature may be 370 degreeC), it cools immediately to 370 degrees C or less. This is because if the cooling to 370 ° C. or lower takes time, the extraction rate decreases accordingly. Here, “immediately cool” means to cool by applying a cooling process as quickly as possible. For example, as soon as possible until the slurry moves to a gravity settling tank described later. In other words, it is cooled by a cooling process.

  Further, the extraction rate is higher as the heating time (extraction time) at a temperature of 400 to 420 ° C. (the lower limit temperature may be 370 ° C.) is shorter. Therefore, in order to further improve the extraction rate, the heating time (extraction time) ) Is preferably 15 minutes or less, more preferably 10 minutes or less, and even more preferably 5 minutes or less. Furthermore, it is more preferable to cool to 370 ° C. or less immediately after the temperature is raised to 0 minutes, that is, 400 to 420 ° C. for extraction.

  Furthermore, in the temperature range of 400 to 420 ° C. (the lower limit temperature may be 370 ° C.), a temperature close to 400 ° C. is preferable, and 400 ° C. is preferable. This is because the closer to 400 ° C., the higher the extraction rate. In this heating extraction, the coal is thermally decomposed to produce aromatic-rich components mainly having an average boiling point (Tb50: 50% distillation temperature) of 200 to 300 ° C. Can be used as part.

  Heat extraction is preferably performed in a non-reducing atmosphere. Specifically, it is performed in the presence of an inert gas. This is because contact with oxygen during heating extraction is dangerous because it may ignite, and the cost increases when hydrogen is used.

  As the inert gas used in the heat extraction, inexpensive nitrogen is preferably used, but is not particularly limited. The pressure in the heat extraction is preferably 1.0 to 2.0 MPa, although it depends on the temperature at the time of heat extraction and the vapor pressure of the aromatic solvent used. When the pressure is lower than the vapor pressure of the aromatic solvent, the aromatic solvent volatilizes and is not trapped in the liquid phase and cannot be extracted. In order to confine the aromatic solvent in the liquid phase, a pressure higher than the vapor pressure of the aromatic solvent is required. On the other hand, if the pressure is too high, the cost of the equipment and the operating cost increase, which is not economical.

<Separation step (S2)>
The separation step (S2) is a step of separating the slurry heat-treated in the slurry heating step (S1) into a liquid component and a solid component. Here, the liquid component means a solution containing a coal component extracted into an aromatic solvent, and the solid component means a slurry containing ash and insoluble coal insoluble in the aromatic solvent.

  The method for separating the slurry into a liquid component and a solid component in the separation step (S2) is not particularly limited, but it is preferable to use a gravity sedimentation method.

  As a method for separating a slurry into a liquid component and a solid component, various filtration methods and centrifugal separation methods are generally known. However, the filtration method requires frequent exchange of filter aids, and the centrifuge method tends to cause clogging with undissolved coal components, making it difficult to implement these methods industrially. Therefore, it is preferable to use a gravity sedimentation method that allows continuous operation of fluid and is suitable for a large amount of processing at low cost. Thereby, from the upper part of the gravity sedimentation tank, a liquid component (hereinafter also referred to as “supernatant liquid”) that is a solution containing the coal component extracted into the aromatic solvent is insoluble in the solvent from the lower part of the gravity sedimentation tank. A solid component that is a slurry containing ash and coal (hereinafter, also referred to as “solid content concentrate”) can be obtained.

Hereinafter, an example of the gravity sedimentation method will be described with reference to FIGS. 1 and 2.
As shown in FIG. 2, in the gravity sedimentation method, in the solid-liquid separation device 100, first, coal as a raw material and an aromatic solvent are mixed in a coal slurry preparation tank 1 to prepare a slurry. Next, a predetermined amount of slurry is supplied from the coal slurry preparation tank 1 to the preheater 3 by the pump 2,
The slurry is heated to 400 to 420 ° C. (the lower limit temperature may be 370 ° C.). Then, the heated slurry is supplied to the extraction tank (extractor) 4, heated at 400 to 420 ° C. for 20 minutes or less while being stirred by the stirrer 10, and then immediately cooled to 370 ° C. or less by the cooler 7 (slurry) Heating step (S1)). In addition, it is preferable to provide a cooling mechanism in the extraction tank 4 for immediate cooling. In addition, “20 minutes or less” here means the total heating time in the preheater 3 and the extraction tank 4, and immediately after the preheater 3 starts heating at 400 to 420 ° C. Time until cooling to 370 ° C. or lower. And the slurry which performed this extraction process is supplied to the gravity sedimentation tank 5, and a slurry is isolate | separated into a supernatant liquid and solid content concentrated liquid (separation process (S2)), and settled in the lower part of the gravity sedimentation tank 5. The solid concentrate is discharged to the solid concentrate receiver 6 and the upper supernatant liquid is discharged to the filter unit 8 by a predetermined amount.

  Here, in the gravity settling tank 5, in order to prevent reprecipitation of the solute eluted from the raw material coal, it is preferable to maintain the temperature at 330 to 370 ° C., that is, the temperature after cooling the slurry, Is preferably in the pressure range of 1.0 to 2.0 MPa. Further, in the gravity settling tank 5, the time for maintaining at the cooled temperature is the time required to separate the slurry into the supernatant liquid and the solid concentrate, and is generally 60 to 120 minutes. It is not particularly limited. It should be noted that by increasing the number of gravity sedimentation tanks 5, it is possible to recover components that are soluble in the aromatic solvent accompanying the solid concentration liquid. It is appropriate to arrange in steps. And the supernatant liquid discharged | emitted from the gravity sedimentation tank 5 is filtered by the filter unit 8 as needed, and is collect | recovered by the supernatant liquid receptacle 9. FIG.

  Then, as will be described below, the aromatic solvent is separated and recovered from this liquid component and solid component using a distillation method or the like, and ashless coal having an extremely low ash concentration is obtained from the liquid component (acquisition of ashless coal). Step (S3)). Moreover, by-product charcoal with which ash content was concentrated can be obtained from a solid component as needed.

<Ashless coal acquisition process (S3)>
The ashless coal acquisition step (S3) is a step of separating the aromatic solvent from the liquid component to acquire ashless coal having an extremely low ash concentration.

  As a method for separating the aromatic solvent from the liquid component (supernatant liquid), a general distillation method or evaporation method (spray drying method, etc.) can be used. The aromatic solvent separated and recovered is prepared as a coal slurry. It can be circulated to the tank 1 (see FIG. 2) and repeatedly used. As a result of separation and recovery of the aromatic solvent, the concentration of ash content of residual inorganic substances (silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, etc.) when coal is incinerated by heating at 815 ° C. As a result, ashless coal with very little can be obtained. The ash content of this ashless coal is 5000 ppm or less (mass basis), preferably 2000 ppm or less. Moreover, this ashless coal does not have any water | moisture content, and shows the performance (thermal fluidity | liquidity) far superior to raw material coal.

  If necessary, in the ashless coal acquisition step (S3), in addition to obtaining ashless coal, the aromatic solvent is separated from the solid component separated in the separation step (S2), and the modified coal You may manufacture by-product coal which is (by-product coal acquisition process).

  The method for separating the aromatic solvent from the solid component (solid content concentrate) is the same as the above-described ashless coal acquisition step (S3) for acquiring ashless coal from the liquid component. The aromatic solvent that can be used and separated and recovered can be circulated to the coal slurry preparation tank 1 (see FIG. 2) and repeatedly used. By separation and recovery of the aromatic solvent, by-product charcoal enriched in ash can be obtained from the solid concentrate.

  Note that only ashless coal without ash from the liquid component is produced as the raw material for the carbon raw material, and only the aromatic solvent is recovered from the solid component, and the ash-enriched byproduct coal may be used as fuel. .

<Ashless charcoal heating process (S4)>
The ashless charcoal heating step (S4) is a step in which the ashless charcoal obtained in the ashless charcoal acquisition step (S3) is heat treated to obtain a carbon raw material. And the volatile matter of the obtained carbon raw material is less than 35 mass% and more than 24 mass%, when measured by the method defined in JIS M 8812. As described above, when the volatile content is adjusted to a predetermined range by heat treatment, the obtained carbon raw material has excellent moldability and self-sinterability.

  Although ashless coal varies depending on the type of coal used as a raw material (coal type) and production conditions, it generally contains 45% by mass or more of volatile matter and 70% by mass or more in severe cases. The fact that it contains a large amount of volatile matter means that it contains a large amount of so-called relatively low molecular weight components, and it is easy to melt. In order to exhibit self-sintering properties, the volatile content needs to be less than 35% by mass. That is, when the volatile content is 35% by mass or more, even if it can be molded, it is deformed in the process of carbonizing the molded body. In addition, the volatile content is not necessarily small. This is because if the volatile content is too small, the ashless coal will be too hard, and pulverization and molding will be difficult. When the volatile content is 24% by mass or more, a carbon raw material having appropriate pulverization properties and moldability can be obtained.

  There is no particular limitation on the heat treatment method for adjusting the volatile matter. It is only necessary to increase the molecular weight of ashless coal by thermal polymerization, to remove a component having a relatively low molecular weight by distillation, or to perform both at the same time. The heat treatment is preferably performed in an inert atmosphere or under reduced pressure. And heat processing conditions are suitably set so that the volatile matter within the predetermined range (less than 35 mass% and more than 24 mass%) may be obtained from the range of the following processing temperature and processing time.

  As processing temperature, 350-425 degreeC is suitable. When the treatment temperature is lower than 350 ° C., the reaction rate (polymerization rate) and the evaporation rate become extremely small, so that a long time is required for the heat treatment, and industrial implementation is difficult. When the treatment temperature exceeds 425 ° C., the reaction rate and the distillation rate become too high, and it is very difficult to control the volatile matter, making industrial implementation difficult. The treatment time varies depending on the properties of ashless coal, the volatile content range to be obtained, or the treatment temperature, but is generally about 30 minutes to 6 hours. It goes without saying that it takes a longer time to perform at lower temperatures.

  In addition, heat processing may heat-treat only ashless coal, or heat-process in the ashless coal solution state using an aromatic compound, coal tar, etc. as a solvent, and isolate | separate ashless coal after that. You can also do it.

  The method for producing a carbon raw material according to the present invention is as described above. However, in performing this production method, for example, raw material coal is used during or before and after each step within a range that does not adversely affect each step. Other steps such as a coal pulverizing step for pulverizing the ash, a removing step for removing unnecessary materials such as dust, and a drying step for drying the obtained ashless coal may be included.

<< Coke production method >>
The method for producing coke according to the present invention is similar to the method for producing carbon raw material according to the present invention, and is a method in which the ashless coal heating step (S4) of the method for producing carbon raw material is replaced with a dry distillation step. . That is, the method for producing coke according to the present invention includes a slurry heating step (S1), a separation step (S2), an ashless coal acquisition step (S3), and a dry distillation step. What is suitable as a manufacturing method of this coke has the pre-processing process for reducing the expansibility with respect to the ashless coal obtained at the ashless coal acquisition process (S3) before the dry distillation process.

  Hereinafter, the present invention will be described by taking a method for producing coke having a pretreatment step as an example, except for the ashless coal heating step (S4), which is the same as the method for producing a carbon raw material according to the present invention, The description may be omitted.

<Pretreatment process>
In the pretreatment step, the expansibility of the ashless coal obtained in the ashless coal acquisition step (S3) is reduced as described above. The ashless coal treated in this step is substantially free of inert knit that does not exhibit softening and melting properties. Here, the presence or absence of inert knit can be confirmed by a method based on JIS M8816 for ashless coal before dry distillation.

  In addition, as a raw material for coke production that does not contain inert knit, some types of coal pitch and petroleum pitch are also conceivable, but because the carbon ratio in coke is low and the latter has more disadvantages such as more sulfur content, As described above, it is preferable to use ashless coal in the method for producing coke.

  The ashless coal obtained in the ashless coal acquisition step (S3) is usually unsuitable as a raw material for producing high-strength coke because of its generally high expansibility. The expansibility of ashless coal for producing high-strength coke can be confirmed based on the following expansion coefficient, and an expansion coefficient of 1.2 or less is suitable.

The expansion coefficient is calculated as follows. A flat bottom quartz test tube having an inner diameter of 16 mm is filled with 3 g of ashless coal pulverized to a particle size of 1 mm or less so as to have a density of 0.72 to 0.78 g / cm ^3, and a cylindrical barite having the same diameter as that of the test tube. (Weight stone weight: 30 g) is placed on ashless coal, then heated under the conditions of inert gas atmosphere, heating rate of 3 ° C./min, reaching temperature of 1000 ° C., reaching 1000 ° C. for 1 hour, and then cooled. . And the value computed by following Formula is employ | adopted as an expansion coefficient on the basis of the test tube axial direction length of the filled ashless coal.
Expansion rate = (length after heating and cooling) / (length before heating)

The expansion rate of the ashless coal obtained in the ashless coal acquisition step (S3) may exceed 5, and when the expansion rate of the ashless coal is high, in order to reduce the expansion property, air oxidation, heat treatment, Pretreatment of ashless coal may be performed by an appropriate method such as solvent fractionation, and it is preferable to heat-treat the ashless coal under an air atmosphere and conditions of 100 to 350 ° C. When this preferred heat treatment is adopted, the thermal expansion of ashless coal decreases as the treatment time increases, and the thermal expansion coefficient of ashless coal is 1 for producing coke having a DI ⁶⁰⁰ _9.5 of 88.0 or more. The heat treatment time for that is different depending on the heat treatment temperature and the properties of the ashless coal, so it cannot be specified unconditionally, but considering the operability and economy, it is 0.5 hours or more. It is preferably 1 hour or longer.

<Dry distillation process>
In the carbonization step, coke is produced by carbonizing ashless coal. Prior to this dry distillation, ashless coal may be pulverized and / or molded, and a binder such as asphalt pitch may be added to the ashless coal.

  When ashless coal is carbonized, coke is produced through softening, melting, and resolidification of ashless coal. Conditions for this carbonization are not particularly limited, and normal carbonization conditions using a coke oven can be adopted. The temperature condition is, for example, 950 ° C. or more and 1200 ° C. or less, more preferably 1000 ° C. or more and 1050 ° C. or less, and the dry distillation time is, for example, 8 hours or more and 24 hours or less, more preferably 10 hours or more and 20 hours or less.

The obtained coke does not contain carbon derived from inertite in the maceral group of coking coal. As long as normal coal is used as coking coal for coke production, inert coal is inevitably included in the raw coal. Therefore, coke produced using the raw coal contains carbon derived from inert coal. End up. However, if ashless coal that has been appropriately pretreated is used as coking coal, coke containing carbon derived from inertite can be produced because ashless coal substantially does not contain inertite. Why is ashless coal substantially free of inertite? Inertite has a fine structure derived from plants and is characterized as a component that does not heat melt, whereas ashless coal has a coal component. This is because, once dissolved as a molecule in a solvent and precipitated and produced, ashless coal cannot have a fine structure derived from plants, that is, it cannot contain inertinite. The same is true for pretreated ashless coal. Therefore, in the confirmation based on JIS M8816, ashless coal substantially does not contain inertinite.

  Conventionally, it was thought that it was necessary to increase the coke strength by using ordinary coal as coking coal for coke production and appropriately setting the amount of inert coal in this coking coal. As a result of extensive exploration of the liquefaction phenomenon, we found that there is no optimal value for the amount of inertite, but that coke with extremely high strength can be produced if ashless coal substantially free of inertit is pretreated and used appropriately It is. The reason why such a high strength can be realized is not necessarily clear, but is presumed to be as follows. That is, according to the conventional theory of coke strength, the strength of coke derived from inertite (inertite-derived carbon) is the strongest, while the strength of coke derived from active component (active component-derived carbon) is relatively weak, and further derived from inertite. The interface between carbon and active ingredient-derived carbon tends to be a defect, and this defect was considered to be a factor that reduces the strength of coke. However, sufficient coke strength is ensured with only the active ingredient-derived carbon. It is not a conventional two-component coke of inertinite-derived carbon and active ingredient-derived carbon, but a single-component coke that uses only ashless coal that is essentially free of inertinty as the coke production raw coal. If so, it is considered that there are essentially no interface defects that cause a reduction in coke strength.

The strength of the produced coke preferably has a strength index DI ⁶⁰⁰ _9.5 of 88.0 or more. This strength can be realized by appropriately setting pretreatment conditions in the pretreatment step. The upper limit of the strength index DI ⁶⁰⁰ _9.5 is not particularly limited.

  The coke obtained by the above-described method for producing coke according to the present invention can be used for metallurgy of non-ferrous metals such as Si and iron metallurgy as is conventionally known, and can also be used naturally for iron making. is there. That is, it can be used for the manufacture of pig iron. Since the said coke is excellent in intensity | strength, it is used suitably also for pig iron manufacture in a blast furnace. And since the intensity | strength of coke is high, there exists an advantage which can implement | achieve the outstanding air permeability in a blast furnace. Another advantage is coke produced from ashless coal as a raw material, so that there is an advantage that metal is not contaminated in metallurgy (including non-ferrous metallurgy).

  The pig iron production method in the blast furnace may be a known method. For example, iron ore and coke are alternately laminated in layers in the blast furnace, hot air from the bottom of the blast furnace, and if necessary, pulverized coal. Can be mentioned.

Next, the carbon raw material production method according to the present invention will be specifically described with reference to examples. In addition, Examples 1-5 and Comparative Examples 1-6 are the Examples and comparative examples regarding the manufacturing method of the carbon raw material which concerns on this invention (Even if it is the description content regarding Comparative Examples 1-6, it concerns on this invention) If it falls under the coke production method or coke, it falls under the coke production method or coke.)

(Examples 1-5)
A slurry was prepared by mixing 4 kg (20 kg) of aromatic solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.)) with 5 kg of raw coal (bituminous coal). This slurry was pressurized with 1.2 MPa of nitrogen and heat-treated (heat extraction) in an autoclave with an internal volume of 30 liters at 370 ° C. for 1 hour. The slurry was separated into a supernatant and a solid concentrate in a gravity sedimentation tank maintained at the same temperature and pressure, and an aromatic solvent was separated and recovered from the supernatant by a distillation method to produce ashless coal.

Next, 100 g of ashless coal was placed in an autoclave having an internal volume of 0.5 liters, and heat treatment was performed under the treatment conditions (temperature and time) shown in Table 1 under a nitrogen flow of 1 liter / min. The heat-treated ashless coal was used as a carbon raw material. And about this carbon raw material, JIS
Volatiles and ash concentrations were measured by the method defined in M8812. The results are shown in Table 1.

Next, the carbon raw material is pulverized so as to be 0.149 mm or less (passing through a sieve having an opening of 1.149 mm), and the pulverized carbon raw material is filled with 5 g in a mold having a cylindrical cavity with a diameter of 30 mm. Then, it was press-molded at a pressure of 0.5 ton / cm ² to produce a molded body having a thickness of 7.1 mm. The molded body was heated at a rate of 1 ° C./min in a nitrogen atmosphere and carbonized at 1200 ° C. to produce a carbide. About the obtained molded object and carbide | carbonized_material, the external appearance was observed visually and evaluated. Further, the apparent specific gravity of the molded body and carbide was measured. Further, carbon yield of carbide [(W / W ₀ ) × 100, (W) is generated carbon (mass of carbide), (W ₀ ) is mass of carbon raw material (mass of heat-treated ashless coal) ] Was calculated. The results are shown in Table 1.

(Comparative Examples 1-6)
About the comparative example 1, the ashless coal was manufactured by the method similar to an Example, and it was set as the carbon raw material, without performing the heat processing of ashless coal. About Comparative Examples 2-6, the ashless coal was manufactured by the method similar to an Example, and it heat-processed on the process conditions different from the Example shown in Table 1, and it was set as the carbon raw material. And about this carbon raw material, the volatile matter and the ash content density | concentration were measured by the method prescribed | regulated to JISM8812. The results are shown in Table 1. Next, molding and carbonization were performed in the same manner as in the example. About the molded object and the carbide | carbonized_material, it carried out similarly to the Example, the external appearance evaluation, the measurement of apparent specific gravity, and the calculation of the carbon yield were performed. The results are shown in Table 1.

  As shown in Table 1, in the carbon raw materials of Examples 1 to 5, since the volatile content of the carbon raw material is within the scope of the claims, a molded body free from cracks and chips was obtained by compression molding (Table 1). 1 appearance “○”). And this molded object was able to be carbonized without expanding, and it was possible to obtain a dense carbide without cracks and chips and maintaining the shape of the molded object (appearance “◯” in Table 1). . Therefore, it was confirmed that the carbon raw material of Examples 1-5 was excellent in self-sintering property. Also, the ash content of the carbon raw material was as low as 0.08% by mass.

  In the carbon raw materials of Comparative Examples 1 to 4, the ash concentration was extremely low as in the Examples. In addition, a compact without cracks or chipping was obtained by compression molding (appearance “◯” in Table 1). However, since the volatile matter of the carbon raw material exceeds the upper limit, when the molded body is carbonized, it foams violently and expands, and after carbonization, it becomes dense and porous, and the molded body cannot be carbonized while maintaining its shape. (Appearance “×” in Table 1). Therefore, it was confirmed that the carbon raw materials of Comparative Examples 1 to 4 were inferior in self-sintering properties.

  The carbon raw materials of Comparative Examples 5 and 6 had very low ash content as in the Examples. However, since the volatile content of the carbon raw material was below the lower limit value, cracking occurred by compression molding, resulting in a brittle molded product (appearance “x” in Table 1). When the molded body was carbonized, cracks progressed, and part of the molded body collapsed and pulverized, so that a dense carbide could not be obtained (appearance “x” in Table 1). Therefore, it was confirmed that the carbon raw materials of Comparative Examples 5 and 6 were inferior in self-sintering properties.

  Next, the manufacturing method of the coke which concerns on this invention, the Example about a coke, and a comparative example are shown.

  The ashless coal produced in the same manner as in the above Examples was pulverized to 1 mm or less, and subjected to pretreatment (see Table 2 below for pretreatment time) in air at 140 ° C. to evaluate the expansibility. Moreover, expansibility was evaluated also about the ashless coal which did not pre-process.

The expansibility was evaluated as follows. The sample was pulverized to a particle size of 1 mm or less, and 3 g of the pulverized sample was filled into a flat bottom quartz test tube having an inner diameter of 16 mm so as to have a density of 0.72 to 0.78 g / cm ³ . After placing a cylindrical barite (massite weight: 30 g) having the same diameter as the inner diameter of the test tube on the sample, an inert gas atmosphere, a heating rate of 3 ° C./min, an ultimate temperature of 1000 ° C., after reaching 1000 ° C. The sample was heated for 1 hour and then cooled. And the expansion coefficient was computed by following Formula on the basis of the test tube axial direction length of the filled sample.
Expansion rate = (length after heating and cooling) / (length before heating)

  The results of pretreatment time and expansion rate are shown in Table 2 below.

  The bituminous coal used in the examples or the ashless coal having an expansion rate of 1.1 after the above pretreatment was used as a raw coal for producing coke, and coke was produced as follows. A can container having a size of width 378 mm × length 121 mm × height 114 mm was filled with coking coal for coke production. Four of these cans are placed in a steel retort (size: width 380 mm × length 430 mm × height 350 mm), and the retort is placed in a double-sided heating electric furnace that can heat the cans in the width direction. The coking coal for coke production was dry-distilled. The dry distillation conditions were 1000 ° C. and 10 hours, and the retort was taken out of the electric furnace and allowed to cool naturally over about 16 hours.

  Four can containers were taken out from the retort after natural cooling, and a 189 mm portion of coke corresponding to half in the width direction was cut out. When performing double-sided heating, the place that hits the middle in the width direction is called a charcoal core, and the calcined coke from the heating surface to the charcoal core is called the head, body, tail from the place close to the heating surface, It is known that a difference in strength occurs due to a difference in heating rate during heating of the head, body, and tail. For this reason, the coke head, body, and tail of the 189mm portion corresponding to half of the width direction are cut into approximately cuboids (one side: approximately 20mm ± 1mm) from each part divided into approximately 60mm and sized. Got coke. The sized coke was washed with distilled water to remove fine coke powder adhering during sizing (at the time of cutting), and dried with a dryer at 150 ° C. ± 2 ° C.

Using the washed and dried coke as a sample for strength measurement, the type I strength (coke strength index DI ⁶⁰⁰ _9.5 ) was measured. The apparatus used for the I-type strength test is a cylindrical container (length: 720 mm, circular bottom diameter: 132 mm) made of SUS material. In this container, 200 g of a strength measurement sample is placed, and 20 minutes per minute. Impacts from a total of 600 rotational motions were applied to the sample at a rotational speed of 1 time. The rotation of the cylinder was performed such that a rotation axis was provided at a position of 360 mm corresponding to the middle of the cylinder length of 720 mm, and the cylinder was rotated around the rotation axis so that the bottom surface of the cylinder drawn a circle with a diameter of 720 mm. After applying an impact by the specified 600 rotations, a sample was taken out from the cylindrical container, and divided by a 9.5 mm sieve to measure the mass on the sieve. At this time, the mass caught on the sieve was also measured on the sieve and the mass was measured. The strength index DI ⁶⁰⁰ _9.5 was calculated as follows.
Strength index DI ⁶⁰⁰ _9.5 = 100 × 9.5 mm Mass on sieve (unit: g) / 200 g

Moreover, when the content of inertite was confirmed based on JIS M8816 about the ashless coal used for manufacture of the coke of an Example, and the bituminous coal used for manufacture of the coke of a comparative example, the inert coal was used for the ashless coal of an Example. The bituminous coal of the comparative example contained 33%.

Table 3 below shows the results of the coke strength index DI ⁶⁰⁰ _9.5 .

It is a flowchart explaining the process of the manufacturing method of the carbon raw material which concerns on this invention. It is a schematic diagram which shows the solid-liquid separator for performing a gravity sedimentation method.

Explanation of symbols

S1 Slurry heating process S2 Separation process S3 Ashless coal acquisition process S4 Ashless coal heating process

Claims (3)

A slurry heating step of heat-treating a slurry containing coal and an aromatic solvent;
A separation step of separating the slurry heat-treated in the slurry heating step into a liquid component in which coal is dissolved and a solid component composed of ash and insoluble coal;
An ashless coal acquisition step of removing the aromatic solvent from the liquid component and acquiring ashless coal;
An ashless coal heating step in which the ashless coal obtained in the ashless coal acquisition step is heat treated to be a carbon raw material,
The volatiles carbon material obtained in the ashless coal heating step, as measured by a method as defined in JIS M 8812, less than 35 wt%, and state, and are more than 24 wt%,
The molding the carbon material obtained in the ashless coal heating process, method of producing a carbon materials, wherein Rukoto obtain a carbon material by carbonization. In the above separation process, the production method of the carbon materials according to claim 1, characterized by the separation of the liquid component and the solid component by gravity sedimentation. Wherein in the no Haisumi acquisition step method of producing a carbon materials according to claim 1 or claim 2, characterized in that conducted by distillation or evaporation to remove the aromatic solvent from the liquid component.

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