JP2014009284A - Coke produced from byproduct coal as main raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide coke produced from byproduct coal as the main raw material.SOLUTION: Coke is produced by molding a raw material for molding into lumps to obtain a molded product, and carbonizing the molded product. The raw material for molding is composed of byproduct coal generated in a process for producing ashless coal by extracting coal with a solvent, coal, and moisture. The coal is 5 mass% (dry base) or less (including 0 mass%) of the raw material for molding, and the moisture is 8 mass% (dry base) or less (including 0 mass%) of the raw material for molding.

Description

  TECHNICAL FIELD The present invention relates to coke mainly using by-product coal produced in the process of producing ashless coal by extracting coal with a solvent.

  In recent years, development of so-called ashless coal (hypercoal) has been actively promoted from the viewpoint of a raw material for a low ash carbon material. Ashless coal is produced by extracting coal with a solvent, separating only the components that are soluble in the solvent, and then removing the solvent (see, for example, Patent Document 1). Structurally, the ashless coal has a wide molecular weight distribution from a relatively low molecular weight component having 2 to 3 condensed aromatic rings to a high molecular weight component having about 5 or 6 rings. In addition, since ash is not dissolved in a solvent, ashless coal does not substantially contain ash, exhibits high fluidity under heating, and is excellent in thermal fluidity. Some coals, such as caking coal, exhibit thermoplasticity at around 400 ° C., but ashless coal generally melts at 200 to 300 ° C. regardless of the quality of the raw coal (softening and melting). Have sex). Therefore, application development as a binder for coke production is being promoted taking advantage of this characteristic, and in recent years, attempts have been made to produce carbon materials by using this ashless coal as a carbon material raw material. .

  In the production of ashless coal, coal is extracted with a solvent, and a solution (extract) containing a component soluble in the solvent is separated to obtain a residue (solid content concentrate) containing a component insoluble in the solvent. Occurs. And a solvent can be removed from this residue and byproduct charcoal can be obtained (for example, refer patent document 2). By-product charcoal contains ash, but has a small amount of water and has a sufficient calorific value. Therefore, for example, it has been studied whether to use as a part of the coal blend of coke raw material or to use it for various fuels such as boiler fuel without using coke raw coal.

JP 2001-26791 A Japanese Patent No. 4061351

  However, there was a need not only to use by-product charcoal as a part of coke blended coal, but also to use it more actively as the main raw material for coke. .

  This invention is made | formed in view of the said need, The subject is providing the coke which uses by-product coal as a main raw material.

  The invention according to claim 1 is a coke obtained by forming a molding raw material into a lump and forming a molded product, and subjecting the molded product to dry distillation, wherein the molding raw material is obtained by extracting coal with a solvent. The coal consists of by-product coal produced in the process of producing ashless coal, coal, and moisture, and the coal is 5% by mass or less (including 0% by mass) of the raw material for molding. And the water content of the raw material is 8 mass% [dry basis] or less (including 0 mass%).

  The invention according to claim 2 is the coke according to claim 1, which is used as blast furnace charging coke.

  The invention according to claim 3 is the coke according to claim 2, which is used as the central charging coke.

  The invention according to claim 4 is the coke according to claim 2, which is used as ore layer mixing coke.

  The invention according to claim 5 is the coke according to claim 1, which is used as coke for casting.

  According to the present invention, by molding a raw material for molding mainly composed of by-product coal containing a small amount of ash-free coal component and dry-distilling, the ash-free coal component in the by-product coal is obtained during dry distillation. While it softens and melts and exhibits caking properties and acts as a binder, the by-product coal main body part excluding ashless coal components is not softened and melted and does not expand and does not generate pores inside. While having the same strength, coke having a higher density than ordinary coke can be obtained. Moreover, such high-density coke can be suitably used as blast furnace charging coke (particularly, center charging coke or ore layer mixing coke) or casting coke such as cupola.

It is a block diagram which shows typically the modified coal manufacturing apparatus for manufacturing the byproduct coal used in order to manufacture the coke which concerns on this invention.

  Next, a method for producing coke according to the present invention (hereinafter also referred to as “by-product coal coke”) will be described. By-product coal coke is obtained by forming a raw material for molding mainly composed of by-product coal into a lump and then subjecting the molded product to dry distillation. This by-product coal produces ashless coal. It is produced from the residue generated in the process. Note that ashless coal and by-product coal are reformed coal obtained by reforming coal.

  Here, before specifically explaining each process for producing by-product coal coke, with reference to the block diagram shown in FIG. 1, modified coal production for producing by-product coal used in the present invention. An example of the apparatus will be briefly described.

  As shown in FIG. 1, the reformed coal manufacturing apparatus 1 supplies a solvent supply tank 2 for supplying a solvent, a coal supply tank 3 for supplying coal, a supply from the solvent supply tank 2 and the coal supply tank 3. After receiving and preparing a slurry, an extraction tank 4 for extracting a coal component (solvent soluble component) soluble in the solvent from the slurry, a solvent (extract) containing the solvent soluble component, and a coal component insoluble in the solvent From the separation tank 5 for separating the residue containing ash, the ashless coal recovery tank 6 for recovering ashless coal by removing the solvent from the extract separated in the separation tank 5, and the slurry of the residue separated in the separation tank 5 A by-product coal recovery tank 7 for removing the solvent and recovering the by-product coal.

  Here, the solvent removed from the extract in the ashless coal recovery tank 6 may be returned to the solvent supply tank 2 and reused. Similarly, the solvent removed from the residue in the by-product coal recovery tank 7 may be returned to the solvent supply tank 2 and reused. The ashless coal recovered in the ashless coal recovery tank 6 contains substantially no ash because the ash is not dissolved in the solvent, has a water content of approximately 0.5% by mass or less, and is higher than the raw coal. Indicates the calorific value. This ashless coal can be used as a raw material for various carbon materials, as a binder for iron-making coke and forming coal, and the like.

  If the solvent-soluble component and the component unnecessary for the solvent are completely separated in the separation tank 5, ashless coal substantially free of ash can be produced as described above. From the viewpoint of pursuing product performance, it is allowed that a certain amount of ash and unnecessary coal components are mixed in the ashless coal. For example, even if 1 to 3% by mass of ash is contained in ashless coal, there is no problem depending on the application.

  On the other hand, the by-product coal recovered in the by-product coal recovery tank 7 contains ash that was not dissolved in the solvent. Although this by-product charcoal contains ash, it has a small amount of water and has a sufficient calorific value.

  Hereinafter, an embodiment of a method for producing a molded product according to the present invention will be described using the modified coal production apparatus 1 having such a configuration as an example. The method for producing a molded product according to the present invention includes a modified coal production process and a molding process. Hereinafter, each step will be described.

<Modified coal production process>
The modified coal production process of the present invention is a process of collecting by-product coal. Furthermore, it is also a process of recovering ashless coal. That is, the modified coal manufacturing process includes a by-product coal recovery process and an ashless coal recovery process. Specifically, first, coal supplied from the coal supply tank 3 and the solvent supplied from the solvent supply tank 2 are mixed to extract a coal component soluble in the solvent from the coal in the extraction tank 4. . Then, it isolate | separates into an extract and a residue with the separation tank 5, and isolate | separates the said solvent from the said residue by a distillation method or an evaporation method with the byproduct charcoal recovery tank 7, and collect | recovers byproduct charcoal. Further, here, the ashless coal is recovered by separating the solvent from the extract in the ashless coal recovery tank 6 by distillation or evaporation. Here, the extract means a solution containing a coal component extracted in a solvent, and the residue means a solute containing a coal component insoluble in the solvent (coal containing ash, that is, ash coal).

  Known methods can be used as a method for obtaining modified coal (ashless coal and by-product coal), and solvent types and production conditions are designed as raw materials for use such as the properties of carbon and carbon materials. In view of this, it is appropriately selected. A typical method is to mix a coal with a solvent that has a high solvent power for coal, often an aromatic solvent (hydrogen donating or non-hydrogen donating solvent), and heat it in the coal. It is a method of extracting the organic component. However, in order to obtain the modified coal with higher efficiency and lower cost, for example, it is preferable to produce the modified coal by the following method. In the method, first, in the extraction tank 4, a mixture (slurry) obtained by mixing the coal supplied from the coal supply tank 3 and the non-hydrogen donating solvent supplied from the solvent supply tank 2 is heated to produce non-hydrogen. Extract coal components that are soluble in the donor solvent. Next, in the separation tank 5, the extracted slurry is separated into an extract and a residue. And in the ashless coal collection tank 6, ashless coal is collect | recovered by isolate | separating the said non-hydrogen-donating solvent from the said extract. Further, in the byproduct coal recovery tank 7, the byproduct coal is recovered by separating the non-hydrogen donating solvent from the residue.

  There is no restriction | limiting in particular as coal for solvent extraction, Bituminous coal with a high extraction rate (ashless coal recovery rate) may be sufficient, and cheaper inferior quality coal (subbituminous coal, lignite) may be sufficient. The coal is preferably pulverized into as small particles as possible, and the particle size (maximum length) is preferably 1 mm or less.

  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. This non-hydrogen-donating solvent is stable even in a heated state and has excellent affinity with coal. Therefore, the proportion of soluble components (herein, coal components) extracted into the solvent (hereinafter also referred to as extraction rate) In addition, it is a solvent that can be easily recovered by a method such as distillation. The main components of the non-hydrogen donating solvent include bicyclic aromatic naphthalene, methyl naphthalene, dimethyl naphthalene, trimethyl naphthalene and the like, and the other components of the non-hydrogen donating solvent have an aliphatic side chain. Naphthalenes, anthracenes, fluorenes, and also include biphenyl and alkylbenzenes with long-chain aliphatic side chains.

  The extraction rate of coal can be increased by heat extraction using a non-hydrogen-donating solvent. In addition, unlike polar solvents, the solvent can be easily recovered, so that it is easy to circulate the solvent. Furthermore, since it is not necessary to use expensive hydrogen, a catalyst, or the like, coal can be solubilized at a low cost to obtain reformed coal, and economic efficiency can be improved. In the present invention, the solvent is not limited to a non-hydrogen donating solvent such as a bicyclic aromatic compound. That is, hydrogen donating solvents such as tetralin and coal liquefied oil are expensive but generally give a high ashless coal yield. Therefore, it is also within the scope of the present invention to use a hydrogen donating solvent as the solvent.

  Although the coal density | concentration with respect to a 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. If the coal concentration with respect to the solvent is less than 10% by mass, the proportion of the coal component extracted into the solvent decreases with respect to the amount of the 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 prepared slurry becomes high, and it becomes difficult to move the slurry and separate the extract from the residue.

  The heating temperature of the slurry is preferably in the range of 300 to 450 ° C. By setting the heating temperature within this range, the bonds between the molecules constituting the coal are loosened, mild thermal decomposition occurs, and the extraction rate becomes the highest. If heating temperature is less than 300 degreeC, it will become inadequate to weaken the coupling | bonding between the molecules which comprise coal, and an extraction rate will not improve easily. On the other hand, when the temperature exceeds 450 ° C., the pyrolysis reaction of coal becomes very active and recombination of the generated pyrolysis radicals occurs, so that the extraction rate is hardly improved and the alteration of coal is difficult to occur. In addition, More preferably, it is 350-400 degreeC.

  The heating time (extraction time) is a criterion for reaching the dissolution equilibrium, but it is economically disadvantageous to realize it. Therefore, since it differs depending on conditions such as the particle diameter of coal and the type of solvent, it cannot be generally stated, but it is usually about 10 to 60 minutes. If the heating time is less than 10 minutes, the extraction of the coal component tends to be insufficient, while if it exceeds 60 minutes, the extraction does not proceed any further, which is not economical.

  The extraction of the coal component soluble in the non-hydrogen donating solvent is preferably performed in the presence of an inert gas. This is because contact with oxygen is dangerous because it may ignite, and when hydrogen is used, the cost increases. As the inert gas to be used, inexpensive nitrogen is preferably used, but is not particularly limited. The pressure is preferably 1.0 to 2.0 MPa, although it depends on the temperature at the time of extraction and the vapor pressure of the solvent used. When the pressure is lower than the vapor pressure of the solvent, the solvent is volatilized and is not trapped in the liquid phase and cannot be extracted. In order to confine the solvent in the liquid phase, a pressure higher than the vapor pressure of the 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.

  Thus, the slurry after extracting a coal component is isolate | separated into an extract and a residue. As a method for separating the slurry into the extract and the residue, various filtration methods and centrifugal separation methods are generally known. However, the filtration method requires frequent replacement of the filter, and the centrifugation 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 settling tank corresponding to the separation tank 5, an extract liquid (hereinafter, also referred to as a supernatant liquid) that is a solution containing coal components extracted into the solvent is transferred from the lower part of the gravity settling tank to the solvent. It is possible to obtain a residue (hereinafter also referred to as a solid concentrate) that is a solute containing a coal component that is insoluble in water. Although it is ideal that the extract and the residue are completely separated, the residue is mixed in a part of the extract or the extract is mixed in a part of the residue, though it is a little.

  And ashless coal is obtained by isolate | separating a non-hydrogen-donating solvent from this supernatant liquid (extract). Moreover, by-product charcoal is obtained by isolate | separating a non-hydrogen donating solvent from solid content concentrate (residue). As a method for separating the solvent from the supernatant or solid concentrate, a general distillation method or evaporation method (spray drying method, etc.) can be used. From the supernatant, ashless substantially free of ash. Charcoal can be obtained. In addition, by-product charcoal containing ash can be obtained from the solid concentrate. Note that by-product charcoal recovery and ashless coal recovery may be performed first or simultaneously. And the byproduct coal manufactured by the modified coal manufacturing apparatus 1 in this way is provided to a formation process.

  Here, when separating the non-hydrogen donating solvent from the solid concentrate (residue) and recovering the by-product charcoal, the non-hydrogen donating property is obtained by a distillation method or an evaporation method performed at a temperature higher than the boiling point of the non-hydrogen donating solvent Since the solvent is separated, the by-product coal obtained by recovering from the solid concentrate is, for example, in a high temperature state with a temperature of about 150 to 300 ° C. and a moisture content of 0.2 to 3. It is a dry state of about 0% by mass.

  Moreover, the byproduct charcoal obtained by collecting from the solid concentrate is finely powdered, and the particle size (maximum length) is about 0.2 to 1.0 mm. However, in the by-product charcoal, secondary particles in which particles having a particle size (primary particle size) of about 0.2 to 1.0 mm are aggregated are also present. The particle size (secondary particle size) of the secondary particles is, for example, about 0.2 to 50 mm, although it depends on the by-product coal recovery conditions.

  In this way, by-product coal is obtained in a fine powder form in the modified coal production process, raw material coal of usually 3 mm or less, or 1 mm or less is used. This is because the process proceeds. In this way, by-product charcoal is originally obtained in the form of fine powder, so the process of crushing by-product charcoal to fine powder is basically unnecessary prior to the production of the subsequent molded product (however, it is agglomerated and coarsened). In the case of mixed secondary particles, crushing and crushing may be required, but the load is not so large compared to crushing coal.) By using it, coke manufacturing costs can be reduced. On the other hand, if an attempt is made to produce a molded product using only coal without using by-product coal, it is necessary to pulverize the coal or add a binder, which increases the production cost of coke. .

<Molding process>
The forming step is a step in which the recovered by-product charcoal is used as a main component and formed into a lump without using a binder to form a molded product. The molded product as used herein refers to a molded product having a predetermined three-dimensional structure obtained by molding a molding raw material mainly composed of byproduct charcoal into a lump shape. The molding can be molded using a molding machine such as compression molding or two-roll tablet molding.

  Since the molding raw material may contain moisture at the time of molding as described later, it is preferably 120 ° C. or lower. On the other hand, molding is easier at a temperature higher than room temperature, and the strength is further improved. A molding is obtained. Specifically, it is preferably 30 ° C. or higher, and more preferably in the range of 60 to 90 ° C. Such a temperature is assumed to be when the molding material is filled in the molding die. Therefore, when the temperature of the molding material is low, the molding material may be preheated with a heater or the like so that the molding temperature is 30 ° C. or higher, or the mold may be filled. You may make it heat, heating and shaping | molding with a heater etc.

  In order to secure the strength of the coke obtained after dry distillation, the by-product coal occupies 90% by mass [dry basis] or more, preferably 95% by mass [dry basis] of the raw material for molding. The main component is by-product coal. Here, “mass% [based on dry weight]” means mass% with respect to the molding raw material in a dry state.

  In addition, when forming the molded product, when the by-product coal obtained in the modified coal production process is mixed with the coarse secondary particles, by crushing and pulverizing, by-product coal particle size adjustment. The by-product charcoal having the adjusted particle size may be guided to a molding machine.

  Further, in the molding of the molded product, for the purpose of improving the flowability of the powdery by-product coal in continuous molding, the powdery particle size is adjusted to 1 mm or less, preferably 0.5 mm or less with respect to the by-product coal The coal may be added to the molding machine. As the particle size of the powdered coal is reduced, the strength of the molded product increases. However, if the ratio of 50 μm or less is 30% by mass or more, it is not good because it becomes difficult to mold. In addition, for example, powdered coal having a particle size of 1 mm or less is when pulverized coal after pulverization is sieved with a sieve having a mesh opening of 1 mm or less (metal mesh sieve, standard number JIS Z 8801-1 (2006)). It means that the powder is under the sieve. When the powdered coal is added to the by-product coal, the strength of the coke is lowered if the amount is too large, so the ratio of the powdered coal to the total mass (raw material) including these Is at most 5 mass% [dry basis]. The type of coal to be added in the form of powder is not particularly limited, and is arbitrarily selected from strong caking coal, semi-caking coal, weak caking coal, non-caking coal, boiler coal, and the like. Can be selected.

  Further, when molding a molded product, it is preferable to adjust the water content of the molding material in order to perform molding more efficiently (with high productivity). However, if the moisture content of the forming raw material is too high, the apparent density of the molded product decreases, the apparent density of the coke obtained after dry distillation also decreases (that is, the porosity increases), and the desired density is obtained. Coke cannot be obtained. Therefore, the moisture content of the forming raw material is 8% by mass or less. From the viewpoint of increasing the efficiency of molding, the preferable range of the water content of the molding raw material is 0.5 to 8% by mass, and further 1 to 3% by mass.

In addition, the size of the molded product can be appropriately changed according to requirements. For example, it has a cylindrical shape (volume 570 cm ³ ) of φ90 mm × 90 mmH.

  As described above, the method for producing a molded product includes a modified coal production process and a molding process. And, in the method for producing this molded product, for example, a coal pulverizing step for pulverizing raw coal, and unnecessary items such as trash can be provided between or before and after each step within a range that does not adversely affect each step. Other steps such as a removing step to be removed may be included.

<Dry distillation process>
In the carbonization step, the molded product is carbonized to produce coke. A known method can be used for dry distillation. For example, a chamber furnace or a continuous carbonization furnace (shaft furnace) can be mentioned. The dry distillation conditions are not particularly limited, and normal dry distillation conditions can be adopted. For example, the carbonization temperature is 950 to 1200 ° C., more preferably 1000 ° C. to 1050 ° C., and the carbonization time is 8 to 24 h, more preferably 10 to 20 h.

  When the molded product is dry-distilled under the above-mentioned conditions, the ashless coal component remaining in the byproduct coal softens and melts in the temperature rising process, and the caking property is expressed and acts as a binder. Since the by-product coal main body part to be removed does not soften and melt and has no expansibility, no bubbles are generated inside. And at higher temperatures, the ashless coal component re-solidifies and cokes, so at least the same strength as normal coke is obtained, and pores are not generated inside, so it has a higher density than normal coke. Coke is obtained.

The strength and density of the produced coke (by-product coal coke) are preferably those having a strength index DI ⁶⁰⁰ _9.5 of 85 or more and less than 88 and a porosity of 36% or less. Such strength and density can be realized, for example, by appropriately adjusting the amount of water added according to the content of the ashless coal component in the byproduct coal and the proportion of the byproduct coal in the molded product. The reason _why the upper limit of the preferred range of the strength index DI ⁶⁰⁰ _9.5 is set to 88 is from the viewpoint of economy considering the production cost of coke.

  As will be described later, by-product coal coke is used in combination with ordinary coke in blast furnace operation (that is, a part of ordinary coke is replaced with coke using by-product coal). It is recommended that by-product coal coke be produced in some carbonization chambers while normal coke is produced in the other carbonization chambers. Of course, for example, by-product coke using coke may be periodically made and stored using the entire carbonization chamber of the chamber furnace.

  Next, a method of using the by-product coal coke produced as described above as blast furnace charging coke will be described.

<Coke for blast furnace charging>
By-product coal coke produced as described above has at least the same strength as ordinary coke for blast furnace, and has a higher density than ordinary coke. The coke can be used from the top of the blast furnace.

  By-product coal coke may be mixed with normal coke and charged to form a coke layer, but it is charged separately from normal coke as central charge coke or ore layer mixing coke. It is particularly recommended to use it.

  That is, the coke center charging method is a method in which a part of coke is charged into the center of the blast furnace by a route different from the normal charging. By this charging method, the carbon solution loss reaction is suppressed by reducing the amount of ore in the center of the blast furnace, and healthy coke with less generation of powder is supplied to the furnace core. As a result, the liquid permeability of the furnace core is improved, and the molten iron flows out through the center of the hearth during extraction. That is, the annular flow of the hot metal in the hearth is suppressed, the rise of the hearth wall temperature can be prevented, and the life of the furnace can be extended.

  Here, if high-density by-product coal coke is used as the core charging coke, the height of the core decreases due to the effect of increasing the inertial force due to the higher density, resulting in destabilization of the furnace. As well as recovering the core, the flow area is widened and the piston flow area extends to the lower part of the furnace, so it can be used to suppress unsteady phenomena such as shelf hanging (Hideki Kawai et al., “Density and friction of core charged particles” ”Numerical analysis of the effect of characteristics on solid particle flow and core behavior in blast furnace”, Iron and Steel, Japan Iron and Steel Institute, 2008, Vol. 94, No. 4, p. 107-114), center The effect of the coke method can be more reliably exhibited.

On the other hand, the coke mixing charging method is a method in which a small amount of coke is mixed in ore and charged into a blast furnace to form an ore layer. CO ₂ generated by gas reduction of the ore in the ore layer is converted into CO ₂ by coke. By improving the ore by reducing the ore, and improving the air permeability of the softened cohesive zone, the stable operation of the blast furnace and the ratio of reducing material are reduced.

  Here, if high-density by-product coal coke is used as ore layer mixing coke, the difference in apparent density from the ore is reduced, so segregation of coke in the ore layer is suppressed, and gas in the ore layer is suppressed. Is suppressed, the gas flow in the shaft portion is improved, and the coke mixing charging effect can be more reliably exhibited. In general, it is known that the gasification reactivity decreases when the density of coke increases, and there is concern that the effect of improving the reducing property of ore may be hindered. However, by-product coal coke has a catalytic effect on the gasification reaction of metal elements (Fe, etc.) contained in high-concentration ash, so the gasification reactivity is not small for high density, and the ore reduction is improved. It does not inhibit the action.

  In addition, by-product coal coke has an ash content of about 10 to 20% by mass (see Examples below), which is higher than that of less than 10% by mass of normal coke. Then, there is a concern about an increase in the amount of slag generated in the blast furnace. However, of the total amount of coke charged to the blast furnace, the ratio of coke used for central charging and ore layer mixing is at most several mass%, so the entire coke charged to the blast furnace is The ash content with respect to is not so high and has little effect on the amount of slag produced in the blast furnace.

  Next, a method of using by-product coal coke as casting coke will be described.

  By-product coal coke has high strength and high density, so that it can be suitably used as casting coke in addition to the above-mentioned blast furnace center charging coke and ore layer mixing coke.

  That is, in a typical cupola as a cast iron melting furnace, coke is used as a heat source and a carburizing material for a shaft furnace. So-called coke for castings is used. In order to produce such coke, conventionally, anthracite and petroleum coke are used in an amount of 20 to 40% by mass and pitch is further used in an amount of 5 to 15% by mass in addition to normal raw coal (Coke Note 2001 edition). P.101). The reason why the ratio of anthracite coal and petroleum coke is increased is that these raw materials do not expand during the dry distillation process and can suppress the formation of pores that cause a decrease in coke density. In addition, the pitch is used to compensate for the reduction in coke strength due to the use of anthracite or petroleum coke having no caking properties. Typical physical properties of cast coke and blast furnace iron coke are shown below (Coke Note 2001, p. 34-35).

Porosity (%) True density (g / cm ³ )
Coke for blast furnace iron making 49 1.84-1.86
Coke for castings 36-40 1.84-1.91

  As shown in the following examples, by-product coal coke satisfies the physical properties of the casting coke, and can be suitably used as casting coke.

  The by-product coal coke has an ash content of about 10 to 20% by mass (see Examples below), and is slightly higher than about 10 mass allowed as a coke for castings. However, it can be used without any problem by adjusting the ash content of the whole coke to about 10% by mass or less in combination with ordinary casting coke.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. Are all possible and are within the scope of the present invention.

[Production of by-product charcoal]
Australian bituminous coal is used as raw coal (ash content: 6.8% by mass), and 4 times (20 kg) of solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.)) is mixed with 5 kg of this raw coal to make a slurry Was prepared. This slurry was pressurized with 1.2 MPa of nitrogen and extracted in a batch-type autoclave with an internal volume of 30 L under the conditions of 370 ° C. and 1 hour (corresponding to the processing by the extraction tank 4 in FIG. 1 described above). This slurry was separated into a supernatant liquid (extracted liquid) and a solid content concentrated liquid in a gravity sedimentation tank maintained at the same temperature and pressure (corresponding to the treatment by the separation tank 5 in FIG. 1 described above). Next, the solvent was separated and recovered from this solid concentrate by a distillation method using a nitrogen stream to obtain by-product coal (corresponding to the treatment by the by-product coal recovery tank 7 in FIG. 1 described above). The yields of ashless coal and by-product coal by the solvent extraction were 51% by mass and 46% by mass, respectively. Moreover, the obtained powdery byproduct charcoal has a water content of 0.1% by mass, an ash content of 12.5% by mass, and an ashless coal concentration remaining in the byproduct coal of 1.0 to 5.0. It was in the range of mass%.

[Molding process]
The by-product coal thus obtained was pulverized to 1 mm or less, and without adding a binder, coal and moisture were added in various addition amounts, and the coal composition shown in Table 1 below was added. Molding raw materials with different ratios or moisture contents were prepared. In addition, as coal, what grind | pulverized the said raw material coal (Australian bituminous coal) to 1 mm or less was used. Then, 350 g of the molding raw material was filled in a mold having an inner diameter of 90 mm, and a cylindrical tablet (molded product) was molded at a mold temperature of 100 ° C. by applying a surface pressure of 3 ton / cm ² . The molded tablets were measured for moisture content, apparent density, and crush strength. The apparent density of the tablet was calculated from its diameter, height and mass. The crushing strength was determined by applying a compressive load in a direction perpendicular to the center axis of the cylindrical tablet using a crushing tester and measuring a load leading to breakage.

[Dry distillation process]
The tablet (molded product) thus produced was subjected to dry distillation under the conditions of dry distillation temperature: 1000 ° C. and heating rate of 3 ° C./min in a N ₂ atmosphere using a small heating furnace.

[Measurement of coke properties]
The tablet (coke) coked by dry distillation was measured for drop strength, true density, and porosity. The drop strength was measured according to JIS K2151 using a drop strength tester.

[Test results]
The test results are shown in Table 1. About the tablet (coke) after dry distillation, the case where the porosity was 36% or less and the drop strength was 85 or more was regarded as acceptable. In Table 1, those outside the specified range of the present invention and those not satisfying the acceptance criteria are shown by shading numerical values and the like.

  As shown in Table 1, sample No. 1-4, 6, and 7 are invention examples that satisfy the requirements of the present invention, and the physical properties of the coke after dry distillation satisfy the acceptance criteria, have sufficient strength, and have high density coke. .

  In contrast, sample no. No. 5 has excessive moisture in the forming raw material. In Nos. 8 and 9, the coal in the forming raw material is excessive, and the physical properties of coke after dry distillation do not satisfy the acceptance criteria.

  Therefore, the coke according to the present invention (by-product coal coke) is very high strength and high density as coke, coke for blast furnace, particularly as coke for central charging or ore layer mixing, or cupola etc. It was confirmed that it could be suitably used as a casting coke.

DESCRIPTION OF SYMBOLS 1 ... Modified coal manufacturing apparatus 2 ... Solvent supply tank 3 ... Coal supply tank 4 ... Extraction tank 5 ... Separation tank 6 ... Ashless charcoal recovery tank 7 ... Byproduct charcoal recovery tank

Claims (5)

  A molding material is formed into a lump to form a molded product, and coke obtained by dry distillation of the molded product. The molding material is a process in which coal is extracted with a solvent to produce ashless coal. The by-product coal produced, coal, and moisture are included, and the coal is 5% by mass or less (including 0% by mass) of the raw material for molding (including 0% by mass), and the moisture content of the raw material is , 8 mass% [dry basis] or less (including 0 mass%).   The coke according to claim 1, which is used as a blast furnace charging coke.   The coke according to claim 2, which is used as a central charging coke.   The coke according to claim 2, which is used as a coke for mixing ore layers.   The coke according to claim 1, which is used as a casting coke.