JP2013181062A - Molded coal blend, method for manufacturing the same, coke, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded coal blend easy to handle as coal and ashless coal effectively using by-product coal as a by-product when the ashless coal is manufactured by extracting the coal with a solvent and moreover usable as a raw material for coke with enough strength even if by-product coal with low fluidity or the caking property is included.SOLUTION: Molded coal blend is formed by blending ashless coal comprising an element soluble in coal and by-product coal, from which an element soluble in the solvent is eliminated, with granular coal. The coal blend includes 3 wt.% or more of the ashless coal, 8 wt.% or less of the by-product coal, and the balance of granular coal.

Description

  TECHNICAL FIELD The present invention relates to a blended coal using an ashless coal obtained by extracting coal with a solvent and a by-product coal as a by-product, and a method for producing the same. It relates to coke produced from charcoal.

  The coke used for blast furnace iron making has a certain mechanical strength, reactivity, apparent density, and mass size and distribution necessary to ensure air permeability, etc. Various characteristics are required. The coke raw materials that meet these requirements are usually called “coking coal”, compared with high-quality boiler fuel coal, which has a certain range of caking, fluidity, or degree of coalification. Strong caking coal that is expensive and expensive is used. In recent years, attempts have been made to use cheaper and lower quality coal as a raw material for coke against the backdrop of tight resource prices and soaring prices. For example, technological development for blending a large amount of low-grade coal into strongly caking coal Are implemented in various ways.

  In addition, coal is sometimes used as reformed coal that has been modified for effective use of resources, and in recent years, from the viewpoint of high-efficiency use as fuel, so-called ashless coal (hyper coal) is often used. Development is actively underway. Ashless charcoal is obtained by removing most of the ash from the coal, substantially free of ash (target: 200 ppm by mass or less), and structurally has a relatively low molecular weight with two or three condensed aromatic rings. It has a broad molecular weight distribution from components to high molecular weight components of about 5 or 6 rings. Therefore, it exhibits high fluidity under heating. Some coals, like caking coal, exhibit thermoplasticity at a high temperature of about 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 advanced by making use of this characteristic (see, for example, Patent Document 1), and in recent years, a carbon material is produced by using this ashless coal as a raw material. It has been tried.

  Ashless coal is a solvent that has a high affinity with coal. By extracting the coal at a high temperature, ash that does not dissolve in the solvent settles as a residue and is extracted from the extract (liquid part) separated as a supernatant. It is manufactured by removing the solvent (for example, see Patent Documents 2 to 4). On the other hand, the residue (non-liquid part) from which the extract has been separated is recovered by a distillation method or an evaporation method (see, for example, Patent Document 3), and a residue composed of components insoluble in a solvent such as ash is generated as a by-product. . This by-product is called by-product charcoal and contains a lot of ash. However, it is used for various fuels because it has enough calorific value after moisture is removed during the production of ashless coal. be able to. Furthermore, since the by-product coal is derived from steam coal that is not normally used as a coke raw material, if it can be used as a coke raw material, it is considered that coke can be produced at a lower cost.

JP 2008-174582 A Japanese Patent No. 3198305 Japanese Patent No. 4061351 Japanese Patent No. 4708463

  However, by-product coal is a coal component that remains after obtaining ashless coal, which is a caking component, from coal, so it has poor fluidity and caking properties. It was found that the decrease in coke strength was remarkable.

  The present invention has been made in view of the above problems, and its problem is to handle coal blended with by-product coal in order to more effectively use by-product coal, which is a by-product of ashless coal. The present invention is to provide a coke having a sufficient strength when it is dry-distilled as a coke raw material, and a method for producing the same, even if the molded product is excellent in convenience and further contains by-product coal having low fluidity and cohesiveness. .

  In order to solve the above-mentioned problem, the coal blend according to the present invention is granular of ashless coal composed of a component soluble in a solvent in coal and by-product coal obtained by removing the component soluble in the solvent from coal. This is a blended coal blended with the above coal. The blended coal contains 3% by weight or more of the ashless coal, 8% by weight or less of the by-product coal, and the granular coal as a balance. Further, it is preferable that 90% or more of the granular coal has a diameter of 2 mm or less, and more preferably 60% or more has a diameter of 1 mm or less.

  Thus, by prescribing the combination of ashless coal and by-product coal, the coal such as coal that is difficult to organize as a molded product becomes stronger, and coal, ashless coal, and by-product coal are strongly bound to each other by molding, Even if it contains by-product charcoal, it becomes a blended coal that becomes coke with sufficient strength.

  Further, the granular coal preferably has a maximum fluidity MF value (log (ddpm)) of 0.2 to 2.0 and an average maximum reflectance Ro value of 0.8 to 1.1. In this way, by defining coal with predetermined characteristics, even coal that is unsuitable for coke raw material is formed into coal blend that is produced by dry distillation to produce coke with sufficient strength.

  The coke according to the present invention is obtained by dry-distilling a coal mixture containing the above-mentioned coal blended coal. In this way, by using a coal having a predetermined composition, even if it contains by-product coal, the strength becomes sufficient and uniform coke, and coke having a low raw material cost can be obtained.

  In addition, the method for producing a blended coal according to the present invention includes extracting coal with a solvent, separating an extract and a residue, removing the solvent from the extract, and being soluble in the solvent in the coal. Ashless coal production process for producing ashless coal composed of various components, byproduct coal production process for producing byproduct coal by removing the solvent from the residue separated in the ashless coal production process, and coal A coal pulverizing step to pulverize the pulverized coal, a mixing step of mixing the ashless coal and the by-product coal with the granulated coal to form a blended coal, and a molding step of molding the blended coal, Is to do. The mixing step is characterized in that the blended coal contains 3% by weight or more of the ashless coal and 8% by weight or less of the by-product coal. Furthermore, in the molding step, the temperature of the blended coal is preferably 80 to 200 ° C.

  By carrying out according to such a procedure, coal can be pulverized into granules, so that it can be suitably mixed with ashless coal or the like, and the unity at the time of molding becomes strong. Moreover, the shaping | molding combination coal used as the raw material of coke with sufficient intensity | strength can be manufactured by prescribing | mixing the mixture of ashless coal and byproduct coal. Furthermore, by setting the blended coal to a predetermined temperature at the time of molding, the strength of the blended coal is improved and the surface layer is difficult to peel or exfoliate, and the coal, ashless coal, and by-product coal are more strongly bound to each other. Even if it contains raw charcoal, it is a suitable raw material for coke.

  Furthermore, the manufacturing method of the coke which concerns on this invention dry-distills the coal mixture containing the shaping | molding combination coal manufactured with the manufacturing method of the said shaping | molding combination coal. Thus, since the blended coal is already formed, coke that can be used for the production of pig iron can be produced.

  According to the blended coal according to the present invention, a fuel and coke raw material suitable for storage and transportation can be obtained. According to the coke which concerns on this invention, it becomes sufficient intensity | strength at low raw material cost using byproduct charcoal. Moreover, according to the manufacturing method of the shaping | molding coal blend and the manufacturing method of coke which concern on this invention, since by-product coal can be used effectively, the economical efficiency in manufacture of ashless coal improves.

It is a block diagram which shows typically the modified coal manufacturing apparatus for manufacturing the byproduct coal used as the raw material of the shaping | molding blended coal which concerns on this invention.

The formed coal blend and the manufacturing method thereof according to the present invention will be described in detail.
[Formed coal blend]
The coal blend according to the present invention is obtained by mixing ashless coal and by-product coal into coal and forming it into a lump of a predetermined three-dimensional shape as a coal blend. It is used as a blended coal for fuel and coke raw materials. The shape and size of the formed coal blend are not particularly defined and are designed according to the application. Hereinafter, ashless coal, by-product coal, and coal, which are raw materials of the formed blended coal, will be described.

(Ashless coal: 3% by weight or more)
Ashless coal is a modified coal from which ashes and non-soluble coal components are removed from coal as much as possible. It is substantially free of ash, and at the same time contains many components with high fluidity and caking properties. Ashless coal is obtained by extracting coal with a solvent having a high affinity with the coal to obtain an extract from which insoluble components such as ash are separated, and removing the solvent from the extract by evaporation or the like. Manufactured. Accordingly, ashless coal contains a large amount of organic matter that is soluble and soft and soluble in the solvent among the coal components, and is dehydrated in a mixture (slurry) of coal and solvent before extraction and separation. Therefore, the moisture is reduced to about 0.2 to 3% by mass. Therefore, ashless coal contains a large amount of volatile matter, has excellent thermal fluidity, and has high caking properties, so it may be contained together with low-grade coal and by-product coal such as weakly caking coal and non-caking coal. In particular, as described later, it is molded by heating and has a certain degree of strength, generation of dust is suppressed, and it becomes a blended coal suitable for storage and the like. It is possible to give coke with high strength and coke. In order to give sufficient strength when coke is made in this way, the ashless coal has a content (excluding moisture) in the formed blended coal of 3% by weight or more, and further according to the fluidity of the blended coal. Prepared. The upper limit of the content of ashless coal is not particularly specified, but if it is too much, the strength is lowered when it is made coke, and it is preferably 10% by weight or less. The ashless coal is preferably as small as possible in order to increase the strength of the blended coal and coke, and specifically, the diameter (maximum length) is preferably 1 mm or less. In this invention, quality does not ask | require about raw material coal for obtaining ashless coal. Details of the method for producing ashless coal will be described later.

(By-product charcoal: 8 wt% or less)
By-product coal is a by-product generated in the process of producing ashless coal from coal. As described above, ashless coal is produced by extracting a component soluble in a solvent from coal. On the other hand, the insoluble components separated as a residue are further removed from the solvent to become by-product coal. Therefore, the by-product coal has low softening meltability because the organic matter soluble in the solvent and softening and melting is removed from the raw coal as ashless coal, and the ash content insoluble in the solvent is low. Is concentrated from the raw material coal to a high concentration of about 10 to 20% by mass. However, the main component of by-product coal is carbon (C), as is the case with coal, and, like ashless coal, it is dehydrated in a mixture (slurry) of coal and solvent before extraction and separation. Therefore, the water content is reduced to about 0.2 to 3% by mass and has a sufficient calorific value. By-product charcoal has low fluidity and does not have caking properties. If it is contained in a large amount, strength decreases when coke is formed. Therefore, the content (excluding moisture) in the formed blended coal is 8% by weight or less, Furthermore, it is prepared according to the coalification degree and fluidity of coal to be blended and blending of ashless coal, and is preferably 1% by weight or more. The by-product coal is preferably as small as possible in order to increase the strength of the blended coal and coke, and specifically, the diameter (maximum length) is preferably 1 mm or less. In addition, the ash content in coal refers to a residual inorganic substance when coal is incinerated by heating to 815 ° C. and includes silicic acid, alumina, iron oxide, lime, magnesium oxide, alkali metal oxide, and the like. In the present invention, the quality of the raw material coal for obtaining by-product coal does not matter as in the case of ashless coal. The details of the production method of by-product coal will be described later as part of the ashless coal production process. Moreover, the ashless coal and the by-product coal do not need to be manufactured from the same raw material coal, and do not need to be based on the same manufacturing apparatus and method.

(coal)
About coal, the kind (quality, quality) is selected according to the use of forming blended coal. In particular, in the case of blending coal as a coke raw material, the maximum fluidity MF value (log (ddpm)): 0.2 to 2.0, and the average maximum reflectance Ro value: 0.8 to 1.1 are preferable. . Coal having an MF value of less than 0.2 and an Ro value of less than 0.8 is too low in quality and unsuitable for coke, or extremely reduces the blending and does not reduce costs. On the other hand, coal having an MF value exceeding 2.0 and an Ro value exceeding 1.1 can be produced alone in coke, resulting in high raw material costs. That is, in the bituminous coal, the raw material cost can be reduced by applying the medium-low coalification degree medium-low fluidity coal, which is generally difficult to be used as a coke raw material. Moreover, you may apply two or more types of coal which differ from these ranges of coalification and fluidity | liquidity. In the blended coal, the coal can be contained in an amount of 80% by weight or more, further 85% by weight or more in terms of dry coal. In addition, although coal is good also as dry coal by air drying etc., it may be mixed and shape | molded with ashless coal and byproduct coal in the state containing the water | moisture content.

  The coal is preferably finely pulverized in the same manner as ashless coal and by-product coal. Specifically, 90% or more of the coal is preferably granular with a diameter of 2 mm or less. It is more preferable that the percentage is more than 1 mm in diameter. In this specification, the particle diameter refers to the maximum length of a particle, and 90% or more is a particle having a diameter of 2 mm or less. When coal is passed through a sieve having an eye size of 2 mm, 90% or more is an eye. It means to pass through. In the coal blend according to the present invention, the strength of the coal blend can be increased as the particle size of the coal, ashless coal, and by-product coal is smaller, and the strength when coke is further increased. .

  The coal blend according to the present invention preferably contains a trace amount of water. Water becomes a so-called binder (binder) for bonding ashless coal, by-product coal, and coal particles into a lump, and improves the strength of the blended coal. The water is not particularly defined, and generally used water such as tap water can be used. Therefore, if it is a liquid, it can be molded with water other than water, but water is cheap and easily available, and is also attached to and impregnated with coal itself, and is contained in an amount of about 2 to 8% by mass. In the blended coal, water is added to the coal, including the amount contained in ashless coal and by-product coal, so that it is 0.5 mass% or more and 13 mass% or less. It is preferable to adjust. In addition, since the amount of moisture before blending coal, that is, molding, is substantially the same even after being formed into the blended coal, the moisture amount may be adjusted when coal or the like is mixed. Such water is not particularly defined, and generally used water such as tap water can be used. In the coal blend, the water content of less than 0.5% by mass is insufficient to collect coal, ashless coal, and by-product coal during molding. On the contrary, when water exceeds 13 mass%, it will become difficult to form a water film on the surface of each grain of coal, ashless coal, and byproduct coal, and to adhere to each other. Furthermore, it is preferable that water is 4-9 mass%.

[Manufacturing method of coal blend]
The method for producing a formed coal blend according to the present invention includes an ashless coal production process for producing ashless coal from coal, a byproduct coal production process for producing byproduct coal from coal, and pulverizing the coal into granules. A coal pulverization step, a mixing step of mixing the ashless coal, the by-product coal and the coal to obtain a blended coal, and a molding step of forming the blended coal are performed. Hereinafter, each step will be described.

(Ashless coal production process, by-product coal production process)
In the ashless coal production process, coal is extracted with a solvent, and the solvent is removed from the extract obtained by separating the residue to produce ashless coal. On the other hand, the byproduct charcoal production process produces the byproduct charcoal by removing the solvent from the slurry of the residue. That is, by-product coal is a by-product generated in the process of producing ashless coal from coal. Therefore, in the present embodiment, the ashless coal production process and the byproduct coal production process will be described as one process. As long as the by-product coal is an equivalent component, it may not be obtained as a by-product in the production of ashless coal, and ashless coal and by-product coal are produced in the same process. It is not necessary. A well-known method can be used for the method of manufacturing ashless charcoal (for example, refer to patent documents 2 to 4). Below, it demonstrates with reference to an example of the modified coal manufacturing apparatus which can obtain the ashless coal and byproduct coal shown in FIG.

  As shown in FIG. 1, the reformed coal production apparatus 10 includes a solvent storage tank 1, a slurry preparation tank 2 provided with a stirrer, a preheater 3, an extraction tank 4 provided with a stirrer, and a gravity settling tank 5. The solid content concentrate receiver 6 and the supernatant receiver 7 are further provided with a pump, a distillation means (not shown), a cooling mechanism, and the like as will be described later. Hereinafter, as a by-product coal production process, a method for producing ashless coal and by-product coal using the modified coal production apparatus 10 will be described.

  First, a predetermined amount of coal (raw coal) and solvent from the solvent storage tank 1 are supplied to the slurry preparation tank 2 by a pump. In the slurry preparation tank 2, coal and a solvent are mixed with the equipped stirrer to prepare a slurry. At this time, it is preferable to remove the water | moisture content of coal with the dehydrating means which is not shown in figure. A predetermined amount of the slurry is heated in the preheater 3 and further stirred in the extraction tank 4 for a predetermined time, so that the bonds between the molecules constituting the coal are loosened, causing mild pyrolysis, and the extraction proceeds. The solvent-soluble component is separated into a solvent (extract) in which the solvent-soluble component is dissolved and a component insoluble in the solvent (solid content, residue), and is supplied to the gravity settling tank 5.

  Various extraction methods and centrifugal separation methods are generally known as methods for separating the extract and the residue separately, but in the production of ashless coal, continuous operation of the fluid is possible and low It is preferable to use a gravity sedimentation method which is suitable for a large amount of processing at a cost. That is, the extract is taken out as a supernatant in the gravity sedimentation tank 5 and supplied to the supernatant receiver 7 through the filter unit as necessary. In the supernatant receiver 7, the solvent is removed from the extract to produce ashless coal. On the other hand, the portion containing the sediment settled in the lower part of the gravity sedimentation tank 5 (solid content concentrate) is discharged to the solid content concentrate receiver 6, and the solvent is removed by the solid content concentrate receiver 6 to produce by-product coal. (By-product charcoal).

  In the solid content receiver 6 and the supernatant receiver 7, the solvent can be removed from the extract or the solid concentrate by a known method such as an evaporation method such as a distillation method or a spray drying method. it can. Solute (ashless coal) and solid content (by-product charcoal) obtained by removing the solvent are powdery particles having a diameter of about 0.2 to 1.0 mm, or these particles are aggregated as primary particles. In some cases, secondary particles having a diameter of about 50 mm at the maximum are mixed. On the other hand, the solvent (recovered solvent) removed by the solid content receiver 6 and the supernatant receiver 7 is recovered and regenerated as necessary, and is added to the slurry preparation tank 2 and the solvent storage tank 1. It may be supplied and reused. Hereinafter, conditions and the like in each operation will be described.

  Coal used as a raw material for ashless coal and by-product coal does not need to be the same type as the coal mixed in the formed blended coal regardless of the type (quality, quality, brand). Therefore, bituminous coal with a high extraction rate (ashless coal recovery rate) may be used, or cheaper inferior quality coal (subbituminous coal, lignite) may be used. Also, in order to facilitate the extraction and increase the yield of ashless coal, the coal should be pulverized into as small particles as possible before being introduced into the modified coal production apparatus 10 (slurry preparation tank 2). The particle diameter (maximum length) is preferably 1 mm or less.

  The solvent has a high affinity for coal, that is, a solvent that dissolves coal. Examples of such a solvent include monocyclic aromatic compounds such as benzene, toluene, and xylene, polar solvents such as N-methylpyrrolidone (NMP) and pyridine, and the like of ashless coal (and by-product coal). In the production, it is preferable to use a non-hydrogen donating solvent (aromatic solvent) mainly composed of a bicyclic aromatic compound. Therefore, in the byproduct charcoal manufacturing process in the present embodiment, it is assumed that an aromatic solvent is used as the solvent.

  The aromatic solvent which is a non-hydrogen donating solvent is a coal derivative which is a solvent mainly composed of a bicyclic aromatic and purified mainly from a coal distillation product. Since this aromatic solvent is relatively stable even under the above-described extraction conditions and has excellent affinity with coal, the proportion of the soluble component of coal extracted into the solvent (extraction rate) is sufficiently high, As a result, the yield of ashless coal is high, and at the same time, by-product coal in which soluble components remain as a by-product as much as possible is obtained. The aromatic solvent can be easily recovered from the extract or the like by a method such as distillation, and the recovered solvent can be circulated and reused as it is (see FIG. 1). The main components of the aromatic solvent include bicyclic aromatic compounds such as naphthalene, methylnaphthalene, dimethylnaphthalene, and trimethylnaphthalene. Other components include naphthalenes having an aliphatic side chain, anthracenes, and fluorenes. And also include biphenyl and alkyl benzenes with long aliphatic side chains.

  On the other hand, since the hydrogen donating solvent can realize a higher extraction rate regardless of the type of coal, the yield of ashless coal is further increased. Examples of the hydrogen donating solvent include partially hydrogenated aromatic compounds such as tetralin and tetrahydroquinoline, or hydrogenated liquefied oil of coal. However, hydrogen donating solvents are generally more expensive than aromatic solvents, and once used for extraction, most of the hydrogen donating capacity is lost. Otherwise, it cannot be reused, which further increases the cost. Accordingly, the hydrogen-donating solvent is appropriately selected in consideration of the type of coal and the design as a raw material for the intended use, such as use for coal with a low extraction rate with an aromatic solvent. Further, for example, by using an aromatic solvent and a hydrogen donating solvent in combination, the yield of ashless coal can be increased while suppressing costs (see Patent Document 4).

  The amount of coal mixed with the solvent depends on the type of raw coal, but is preferably in the range of 10 to 50 mass%, more preferably in the range of 20 to 35 mass%, based on the dry coal. When the amount of coal is less than 10% by mass, the amount of coal components extracted with respect to the solvent is small, and the productivity is poor. On the other hand, if the coal exceeds the same amount as the solvent, that is, 50% by mass, the prepared slurry becomes highly viscous and fluidity is deteriorated, making it difficult to move between the processing systems (tanks) and to separate the extract from the residue. There is a case.

  When the slurry is heated to a high temperature, the bonds between the molecules constituting the coal are loosened and mild thermal decomposition is performed, and the extraction proceeds. If the temperature of the slurry is less than 300 ° C., it is insufficient for weakening the bonds between the molecules constituting the coal, and the extraction does not proceed sufficiently. On the other hand, when the temperature of the slurry 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 increased and the coal is not easily altered. Become. Therefore, the heating temperature of the slurry is preferably in the range of 300 to 450 ° C, more preferably in the range of 300 to 400 ° C.

  Since the solvent cannot be extracted unless the solvent in the slurry is volatilized and confined in the liquid phase, in the heating (preheating) to extraction of the slurry, the vapor pressure of the solvent at that temperature is used so that the solvent does not volatilize at the heating temperature. High pressure. On the other hand, if the pressure is excessively high, the reformed coal production apparatus 10 requires expensive equipment such as high hermeticity, and the operation cost is also increased. Specifically, although it depends on the temperature at the time of extraction and the vapor pressure of the solvent, the range of 1.0 to 2.0 MPa is preferable. In addition, since extraction is performed at a high temperature, the solvent and coal components, especially components that are soluble in the solvent, may ignite when they come into contact with oxygen. It is preferable to carry out in an inert gas atmosphere.

  The extraction time (the time within the heating temperature range of the slurry) is a standard until reaching the dissolution equilibrium, but if it is attempted to be realized, the productivity is lowered. Therefore, it is preferable to complete the extraction when the increase in the extraction rate is apparently stopped or considerably slowed down. Such preferable extraction time varies depending on conditions such as the particle size of coal and the type of solvent, but is usually about 10 to 60 minutes. If the extraction time is less than 10 minutes, the extraction often does not proceed sufficiently. On the other hand, if the extraction time exceeds 60 minutes, the extraction is difficult to proceed further, and therefore the productivity is poor.

(Coal crushing process)
In the coal pulverization step, the coal mixed with the formed blended coal is pulverized into granules by a conventional method. As for ashless coal and by-product coal, when coarse secondary particles as described above are mixed, the ashless coal and by-product coal are mixed in the same manner as described above. And may be pulverized together.

(Mixing process)
In the mixing step, ashless coal, by-product coal, coal, and water as necessary are mixed to obtain a mixture (blended coal). Ashless coal, by-product coal, coal blending, and water content are as described for the above-mentioned formed blended coal, respectively, and especially water is coal, ashless coal, and byproduct as described above. In consideration of the moisture content of charcoal, adjust by adding the deficiency. For example, by adding ashless coal, by-product coal, and pre-ground coal from a hopper to a known mixer and stirring while adding water by spraying or the like, secondary ashless coal or by-product coal The particles were easily pulverized and heated immediately after the ashless coal and by-product coal were produced in the ashless coal production process and the byproduct coal production process, that is, to a temperature exceeding 200 ° C. for solvent removal. Even immediately after, it is cooled appropriately. When moisture is adjusted in a state where such ashless coal or by-product coal is at a high temperature, water is added in consideration of the amount evaporated until the subsequent molding step.

(Molding process)
In the molding step, the blended coal is molded into a predetermined three-dimensionally shaped lump to form a blended coal. The blended coal can be molded by known compression molding using a molding machine or two-roll briquette molding, which is also applied in the molding of carbon materials such as ashless coal. The pressure applied to the coal blend for molding is not particularly defined, and may be set according to the molding machine or the like.

  A blended coal with higher temperature is easier to mold due to the fluidity of ashless coal, and the strength is further improved. In addition, coal, ashless coal and by-product coal are strongly linked to each other. A suitable coal blend is obtained. Specifically, the blended charcoal is preferably 80 ° C. or higher, and more preferably in the range of 100 to 150 ° C. Such a temperature shall be at the time when the blended coal is filled in the molding die. Therefore, it may be molded by heating the blended coal or the coal before mixing with a heater or the like so that the temperature at the time of molding is 80 ° C. or higher, and filling the mold, for example, mixing blended coal Or may be heated simultaneously with the adjustment of moisture, or may be heated while forming. On the other hand, when the heating temperature rises, the cost increases, and even when heated above 200 ° C., there is no particular improvement effect such as formability and strength. Therefore, the heating temperature of the blended coal is preferably 200 ° C. or less. .

Next, the coke according to the present invention and the manufacturing method thereof will be described in detail.
[Coke]
The coke according to the present invention is obtained by dry-distilling a coal mixture obtained by mixing the above-described coal blend according to the present invention with coal for other coke raw materials under general conditions as described later. The content of the formed coal blend according to the present invention in the coal mixture is preferably 10 to 30% by mass. Examples of coal for coke feed include strong caking coal, semi-caking caking coal, weak caking coal, and non-caking caking coal commonly used for coke feed. As in the case of manufacturing, the pulverization is performed so that, for example, 80% or more has a particle diameter of 3 mm or less. As described above, the blended coal according to the present invention is formed into a desired shape and has a certain strength, so that it is coke that retains the shape by being carbonized together with the coal for the coke raw material. In addition, it is not necessary to arrange | equalize size and a shape with coal for coke raw materials, and shaping | molding mixing coal may be dry-distilled by mixing with coal for coke raw materials with the shape formed according to the magnitude | size. However, when the coal blend is considerably larger than the coke raw material coal (pulverized), segregation occurs in the coke oven wall due to the difference in flowability from the coke raw material coal particles. Therefore, it is preferable that the blended coal is pulverized to the same size as the coal for the coke raw material. As described above, in the coal blend, coal, ashless coal, and byproduct coal are strongly bound to each other by molding, and this tie persists even when pulverized, so it does not affect the effect of mixing the coal blend according to the present invention. . The coke obtained by dry distillation can be directly put into a blast furnace for the production of pig iron.

[Coke production method]
In the present invention, the conditions of dry distillation are not particularly limited, and normal dry distillation conditions in coke production using a coke oven can be adopted. For example, the volume of 10 to 50 in a chamber furnace charged with about 30 tons per gate. % Of the coal mixture is charged and subjected to dry distillation. Preferably it is 950 ° C. or higher, more preferably 1000 ° C. or higher, preferably 1200 ° C. or lower, more preferably 1050 ° C. or lower, preferably 8 hours or longer, more preferably 10 hours or longer, preferably 24 hours or shorter. More preferably, it is carried out by carbonization for 20 hours or less.

  Next, the blended coal and coke according to the present invention and the production method thereof will be specifically described with reference to Examples and Comparative Examples.

[Coke production]
(Manufacture of ashless coal and by-product coal)
First, ashless coal and by-product coal were produced by the following method.
Australian bituminous coal was used as raw material coal, and this raw material coal (converted to dry coal) and 4 times the amount (20 kg) of solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.)) were mixed to prepare a slurry. Nitrogen was introduced into this slurry, the pressure was increased to 1.2 MPa, and the slurry was extracted in a batch-type autoclave with an internal volume of 30 L at 370 ° C. for 1 hour. This slurry was separated into a supernatant and a solid concentrate in a gravity sedimentation tank maintained at the same temperature and pressure, and the solvent was separated and recovered from the solid concentrate by a distillation method to obtain by-product coal. . On the other hand, the solvent was separated and recovered from the supernatant by distillation to obtain ashless coal. The water content of the obtained ashless coal and by-product coal was 1.5% by mass, respectively. Each 1 kg of these ashless coal and by-product coal was pulverized so that the particle size (maximum length) would be 1 mm or less.

(Mixing, molding)
Australian bituminous coal (maximum fluidity MF value (log (ddpm)) 0.5, average maximum reflectance Ro value 1.01) with a water content of 6.7% by mass as coal to be mixed with the blended coal is 1 mm or less in particle size Ashless coal and by-product coal are mixed at a blending ratio (%) shown in Table 1, and water is further added to 0.5 mass% with respect to the total amount. The mixture (mixed charcoal) was prepared by mixing for 10 minutes. The moisture content of bituminous coal is a value measured according to coal JIS (JIS M8812).

Next, this mixture is filled in a mold having a diameter of 20 mm with 6 g per piece, and heated to 120 ° C., applied with a pressure of 2 ton / cm ² , and molded into a cylindrical tablet. did.

  The formed blended coal was placed in a steel retort, and the retort was placed in a double-sided heating electric furnace, and the formed blended coal was dry-distilled in a nitrogen stream. In the dry distillation, the temperature was raised at 3 ° C./min, heated at 1000 ° C. for 20 minutes, and then the retort was taken out of the electric furnace and allowed to cool naturally. In addition, as an evaluation standard, a coke sample (No. 8) was formed from a coal blend containing no by-product coal. The following evaluation was performed about the obtained coke.

[Evaluation]
(Crush test)
A crush test was performed as an index of strength. A compressive load was applied in a direction (radial direction) perpendicular to the cylindrical axis of the coke, and the load leading to fracture was measured. Table 1 shows the measured load as the crushing load. The acceptance criteria for strength was that the crushing load was 100 kg or more.

(Abrasion test)
An abrasion test was performed as an index for suppressing dust generation. First, 20 cokes were accommodated in a cylindrical container having a diameter of 250 mm and rotated at 30 RPM for 10 minutes. Next, the coke taken out from the cylindrical container was selected with a sieve having an opening of 5.66 mm, and the portion that passed through the sieve was weighed. The weight ratio (%) of the portion that passed through (powder) to the entire coke was calculated and is shown in Table 1 as the powder generation rate. The acceptance standard for suppressing dust generation was a powder generation rate of 10% or less.

  As shown in Table 1, sample no. Nos. 1, 5, and 7 are examples that satisfy the scope of the present invention. Although it became lower than 8, what has sufficient intensity | strength as a raw material of coke was obtained. On the other hand, sample No. Nos. 2, 3, and 6 have low strength due to lack of ashless coal, and in particular, Sample Nos. That do not contain ashless coal. 2 was low. Sample No. No. 4 had low strength due to excessive by-product coal.

  The present invention has been described in detail with reference to the embodiments and examples. However, the gist of the present invention is not limited to the above-described contents, and the scope of rights is broadly based on the description of the claims. Must be interpreted. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

DESCRIPTION OF SYMBOLS 10 Modified coal manufacturing apparatus 1 Solvent storage tank 2 Slurry preparation tank 3 Preheater 4 Extraction tank 5 Gravity sedimentation tank 6 Solid concentration receiver 7 Supernatant receiver

Claims (8)

A coal blend formed by blending granular coal with ashless coal composed of a solvent-soluble component in coal and by-product coal obtained by removing the solvent-soluble component from coal. ,
The blended coal contains 3% by weight or more of the ashless coal, 8% by weight or less of the by-product coal, and the granular coal as a balance.   2. The blended coal according to claim 1, wherein 90% or more of the granular coal has a diameter of 2 mm or less.   3. The blended coal according to claim 2, wherein more than 60% of the granular coal has a diameter of 1 mm or less.   The granular coal has a maximum fluidity MF value (log (ddpm)) of 0.2 to 2.0 and an average maximum reflectance Ro value of 0.8 to 1.1. The shaping | molding blend charcoal as described in any one of thru | or 3.   A coke obtained by dry-distilling a coal mixture containing the formed blended coal according to claim 4. Coal is extracted with a solvent, an extract and a residue are separated, and the solvent is removed from the extract to produce ashless coal made of components soluble in the solvent in the coal. Process,
A by-product coal production process for producing by-product coal by removing the solvent from the residue separated in the ashless coal production process;
A coal crushing step for crushing and granulating coal,
A mixing step in which the ashless coal and the by-product coal are mixed with the granulated coal to obtain a blended coal containing 3% by weight or more of the ashless coal and 8% by weight or less of the by-product coal; ,
And a molding step of molding the blended charcoal.   The method for producing a blended coal according to claim 6, wherein in the molding step, the temperature of the blended coal is 80 to 200 ° C.   The manufacturing method of the coke which carbonizes the coal mixture containing the shaping | molding combination coal manufactured by the manufacturing method of the shaping | molding combination coal of Claim 6 or Claim 7.

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