JP2015108065A - Coke production method and coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing coke with high purity at lower cost than a conventional method.SOLUTION: The coke production method of the invention uses: ashless coal; oxidized ashless coal obtained by oxidation treatment to the ashless coal; and petroleum raw coke. With respect to total 100 pts.mass of the ashless coal, oxidized ashless coal, and petroleum raw coke, content of the ashless is 5-40 pts.mass, and total content of the ashless and the oxidized ashless coal is 30-70 pts.mass in the mixture of the ashless coal, oxidized ashless coal, and petroleum raw coke, and the mixture is subjected to dry distillation.

Description

  The present invention relates to a method for producing coke and coke. More specifically, the present invention relates to a method for producing coke suitable for a reducing material for nonferrous metal refining, and coke.

  Conventionally, coke has been used as a reducing material in the refining of non-ferrous metals such as aluminum and titanium. In particular, calcine coke obtained by heating petroleum raw coke (so-called calcined coke) is widely used because it is inexpensive.

  Petroleum coke, the raw material for calcine coke, is a by-product generated during the process of refining oil from crude oil. Therefore, the properties of calcine coke depend on crude oil. For example, impurities (sulfur, nickel, vanadium, sodium, etc.) contained in calcine coke are derived from crude oil as a raw material. Since such impurities become a source of contamination, for example, when used as refining coke, it is desired that impurities (especially the sulfur content, hereinafter the same) be as small as possible. However, since crude oil produced in recent years has a high impurity content, it has been difficult to provide coke with a low impurity content.

  Therefore, the use of ashless coal substantially free of ash as a carbon material having a low impurity content is being studied. For example, Patent Document 1 discloses a method for producing ashless coal used for fuel, coke raw materials, chemical raw materials, and the like.

  However, ashless coal has high heat fluidity and has a property of melting at 200 to 300 ° C. regardless of the quality of the raw coal. Ashless charcoal has the property of expanding when heated to around 400 ° C. Therefore, when ashless coal is molded, heated at a high temperature and subjected to dry distillation treatment, the ashless coal is melted and the shape of the molded body cannot be maintained, and softening meltability has been a problem. In addition, ashless coal foams and expands when heated at high temperatures, overflows from the distillation apparatus, adheres to the inner wall of the distillation apparatus, and cannot be discharged, or the resulting coke becomes a sponge-like porous body and has a bulk specific gravity. There was a problem of expansibility such as a significant decrease. Therefore, ashless coal has problems in softening meltability and expandability, and it has been difficult to use it as a coke raw material.

  In response to such problems, the present inventors have proposed a ashless coal reforming technique (Patent Document 2). Specifically, a slurry heating step for heat-treating a slurry containing coal and an aromatic solvent, a liquid component in which the coal is dissolved in the slurry heat-treated in the slurry heating step, and a solid component composed of ash and insoluble coal The ashless coal acquired in the ashless coal acquisition step, the ashless coal acquisition step of removing the aromatic solvent from the liquid component, and acquiring ashless coal, and the ashless coal acquired in the ashless coal acquisition step are heat-treated. Ashless coal heating step as a carbon raw material, and the volatile content of the carbon raw material obtained in the ashless coal heating step is less than 35% by mass when measured by the method defined in JIS M 8812, and , A method for producing a carbon raw material having a gist of being 24 mass% or more is disclosed.

  According to this technology, by including a slurry heating step, a separation step, an ashless coal acquisition step, and an ashless coal heating step for adjusting the volatile content to a predetermined range, it is low ash and has excellent self-sintering A carbon material having properties can be produced.

JP 2001-26791 A JP 2009-144130 A

  Although the technology of Patent Document 2 has an excellent effect in improving self-sintering properties, it takes time to modify ashless coal, so productivity is not always good, and modified ashless coal is relatively expensive. It was.

  The present invention has been made paying attention to the above-described circumstances, and an object of the present invention is to provide a method for producing high-purity coke at a lower cost than before and a high-purity coke.

  The method for producing the coke of the present invention that has achieved the above-described problem includes ashless coal, oxidized ashless coal obtained by oxidizing ashless coal, and petroleum raw coke, the ashless coal, The total content of the ashless coal is 5 to 40 parts by mass, and the total content of the ashless coal and the oxidized ashless coal is 100 parts by mass in total with the oxidized ashless coal and the petroleum raw coke. It has a gist to dry-distill the mixture which is 30-70 mass parts.

  In the present invention, the mixture is molded and then subjected to dry distillation, the oxygen increase rate of the oxidized ashless coal is 2 to 10%, the oxidation treatment is air oxidation, and the oxidation treatment is 150 ° C. As described above, it is a preferable embodiment to perform at a temperature lower than the ignition point.

It is also a preferred embodiment that the dry distillation is performed in a chamber furnace or a rotary kiln.
The present invention includes ashless coal, oxidized ashless coal obtained by oxidizing ashless coal, and petroleum raw coke, and the ashless coal, the oxidized ashless coal, and the petroleum raw coke, Of the ashless coal is 5 to 40 parts by mass, and the total content of the ashless coal and the oxidized ashless coal is 30 to 70 parts by mass, The coke obtained in this way is also included.

  According to the production method of the present invention, high-purity coke can be produced at low cost using petroleum raw coke. Moreover, according to this invention, a high purity coke can be provided.

FIG. 1 is a flowchart for explaining an example of a manufacturing process of ashless coal. FIG. 2 is a flowchart for explaining an example of a coke production process according to the present invention.

  The present inventors have intensively studied to provide high-purity coke at low cost by using petroleum raw coke as a carbon raw material. As a result, the following knowledge was obtained.

  Ashless coal has a very low impurity content, and mixing ashless coal with petroleum raw coke is useful for reducing the impurity content of coke. However, as pointed out in the prior art, ashless coal has a problem in softening meltability and expansibility.

  Thus, as a result of studies by the present inventors, it was found that if ashless coal is oxidized, the softening meltability and expandability of ashless coal can be improved. However, oxidized ashless coal is finely powdered and has poor caking properties, so in a mixture of oxidized ashless coal and petroleum raw coke, the coke obtained by dry distillation becomes powdery and easily dissipates from the dry distillation equipment. There was a problem that the bulk density of coke also decreased. As a result of diligent investigations to solve such problems, ashless coal becomes oxidized ashless coal and petroleum raw coke by making a mixture containing ashless coal, oxidized ashless coal, and petroleum raw coke. It has been found that it functions as a binding binder and can suppress problems such as coke dusting.

  And, by using a mixture containing ashless coal, oxidized ashless coal, and petroleum raw coke with a predetermined content described later, it becomes possible to suppress melting and expansion of the obtained coke, and to produce high-purity coke. We found that it can be provided at low cost.

  Hereinafter, a method for producing coke according to the present invention will be described based on the flowcharts shown in FIGS. 1 and 2.

  First, the ashless coal used by this invention is demonstrated.

  Ashless coal means ash content of 5% by mass or less, preferably 3% by mass or less. As the ashless coal, those having a very low ash concentration of residual inorganic substances (silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, etc.) when coal is ashed by heating at 815 ° C. are preferred. Specifically, the ash content concentration is more preferably 5000 ppm or less (mass basis), and still more preferably 2000 ppm or less. In addition, ashless coal has no water and exhibits higher thermal fluidity than raw coal.

<Manufacturing process of ashless coal>
Ashless coal can be obtained by various known production methods, for example, by removing the solvent from the solvent extract of coal. For example, ashless coal can be manufactured through the following steps S1 to S3 (see FIG. 1), but the following ashless coal manufacturing steps (S1 to S3) can be appropriately changed, and various processing steps can be performed as necessary. It may be added.

  For example, in the production of ashless coal, within a range that does not adversely affect each step, a coal crushing step for crushing raw coal during or before and after each step, a removal step for removing unnecessary substances such as waste, Other steps such as a drying step of drying the obtained ashless coal may be included.

<Slurry heating process: S1>
The slurry heating step (S1) is a process in which coal and an aromatic solvent are mixed to prepare a slurry, and heat treatment is performed to extract a coal component into the aromatic solvent.
The type of coal as a raw material (hereinafter also referred to as “raw coal”) is not particularly limited. For example, various known coals such as bituminous coal, subbituminous coal, lignite, and lignite can be used. From the viewpoint of economy, it is preferable to use inferior quality coals such as subbituminous coal, lignite and lignite rather than using high-grade coals such as expensive bituminous coal.

  The aromatic solvent is not particularly limited as long as it has a property of dissolving coal. Examples of the aromatic solvent 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. In the present invention, 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 carbonization product of coal. The reason why the non-hydrogen-donating solvent is preferable is that the non-hydrogen-donating solvent is stable even in a heated state and has excellent affinity with coal. This is because it is a solvent that can be easily recovered by a method such as distillation, and the recovered solvent can be recycled.

  If the boiling point of the aromatic solvent is too low, the required pressure in the heat extraction or in the separation step (S2) described later increases, and loss due to volatilization increases in the step of recovering the aromatic solvent. The recovery rate of group solvents is reduced. Furthermore, the extraction rate in heat extraction is also reduced. On the other hand, if the boiling point of the aromatic solvent is too high, 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. The boiling point of the aromatic solvent is preferably 180 to 330 ° C.

  The coal concentration with respect to the aromatic solvent is not particularly limited. Although depending on the type of raw material coal, if the coal concentration relative to the aromatic solvent is low, 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, if the coal concentration is too high, 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). The coal concentration is preferably 10% by mass or more, more preferably 20% by mass or more, preferably 50% by mass or less, more preferably 35% by mass or less, based on dry coal.

  If the temperature of the heat treatment (heat extraction) of the slurry is too low, the bonds between the molecules constituting the coal cannot be sufficiently weakened, and when inferior coal is used as the raw coal, an ashless coal acquisition step (S3 described later) The solidification temperature of ashless coal obtained in (1) cannot be increased. On the other hand, when the heat treatment temperature is too high, the pyrolysis reaction of coal becomes very active, and recombination of the generated pyrolysis radical occurs, so that the extraction rate decreases. The slurry heating temperature is preferably 350 ° C. or higher, more preferably 380 ° C. or higher, and preferably 420 ° C. or lower.

  The heating time (extraction time) is not particularly limited, but if the extraction time is long, the thermal decomposition reaction proceeds too much, the radical polymerization reaction proceeds, and the extraction rate decreases. For example, if it is the said heating temperature, Preferably it is 120 minutes or less, More preferably, it is 60 minutes or less, More preferably, it is 30 minutes or less, Preferably it exceeds 0 minute, More preferably, it is 10 minutes or more.

  After heat extraction, it is preferable to cool to 370 ° C. or lower in order to suppress the thermal decomposition reaction. Further, the lower limit of the temperature at the time of cooling is preferably 300 ° C. or higher. If it cools to less than 300 degreeC, the dissolving power of an aromatic solvent will fall, the reprecipitation of the coal component once extracted will occur, and the yield of ashless coal will fall.

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

  The pressure in the heat extraction depends on the temperature at the time of heat extraction and the vapor pressure of the aromatic solvent used, but when the pressure is lower than the vapor pressure of the aromatic solvent, the aromatic solvent volatilizes and enters the liquid phase. It is not trapped and cannot be extracted. On the other hand, if the pressure is too high, the cost of the equipment and the operating cost increase, which is not economical. A preferable pressure is approximately 1.0 to 2.0 MPa.

<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. The liquid component is a solution containing a coal component extracted into an aromatic solvent. The solid component is a slurry containing ash and insoluble coal insoluble in an 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, and a known separation method such as a filtration method, a centrifugal separation method, or a gravity sedimentation method can be employed. In the present invention, it is preferable to use a gravity sedimentation method that allows continuous operation of a fluid and is suitable for a large amount of processing at a low cost. In the case of the gravity sedimentation method, from the upper part of the gravity sedimentation tank, a liquid component (hereinafter also referred to as “supernatant liquid”) that is a solution containing coal components extracted into an aromatic solvent, and from the lower part of the gravity sedimentation tank, a solvent. It is possible to obtain a solid component (hereinafter also referred to as “solid content concentrate”) which is a slurry containing ash and coal insoluble in water.

  Then, as will be described below, the aromatic solvent is separated and recovered from the supernatant using a distillation method or the like, and ashless coal having an extremely low ash concentration can be obtained (ashless coal acquisition step (S3)). ).

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

  The method for separating the aromatic solvent from the supernatant is not particularly limited, and a general distillation method, evaporation method (spray drying method, etc.), and the like can be used. The aromatic solvent separated and recovered can be used repeatedly. Ash liquid can be obtained from the supernatant by separating and collecting the aromatic solvent. The obtained ashless coal can be used not only as a raw material for the mixture of the present invention but also as a raw material for oxidized ashless coal.

<Other processes>
If necessary, by-product coal in which the ash is concentrated by separating the aromatic solvent from the solid concentrate may be produced (by-product coal acquisition step). The method for separating the aromatic solvent from the solid concentrate can use a general distillation method or evaporation method as in the ashless coal acquisition step (S3) for acquiring ashless coal from the liquid component. .

<Coke production process>
The coke production method of the present invention will be described below with reference to FIG. In the production of coke, within a range that does not adversely affect each process, for example, a pulverization process for pulverizing various raw materials or the like, a removal process for removing unnecessary substances such as dust, etc., before or after each process. Other steps such as a step of subjecting the coke to various treatments may be included.

<Oxidation step: C1>
The oxidation step is a step for obtaining oxidized ashless coal by oxidizing ashless coal. By oxidizing the ashless charcoal, the ashless charcoal can be modified to improve softening meltability and expansibility.

  The oxidation method of ashless coal is not particularly limited. For example, oxidation in an oxidizing atmosphere such as oxygen, ozone, nitrogen dioxide, and air is desirable, and air oxidation using oxygen in the air as an oxidant is preferable.

  The oxygen increase rate of oxidized ashless coal is not particularly limited, but if the oxygen increase rate is too low, the modification effect of ashless coal is not sufficient, and problems may occur due to softening and melting properties during dry distillation. is there. On the other hand, if the rate of increase in oxygen is too high, the yield is reduced, which is not economical. Therefore, the oxygen increase rate is 2% or more, preferably 3% or more, preferably 10% or less, more preferably 5% or less.

  In the present invention, when the oxygen increase rate of ashless coal is set, the ashless coal having an oxygen increase rate lower than the set value even if being oxidized is not handled as the oxidized ashless coal of the present invention. Moreover, when using ashless coal whose oxygen increase rate is lower than an installation value as a carbon raw material, it handles as ashless coal of this invention.

  In the present invention, the oxygen increase rate is obtained by measuring the oxygen content of ashless coal before and after the oxidation treatment based on JIS M 8813 (oxygen content calculation method), and calculating (oxygen content of oxidized ashless coal− The oxygen content of ash coal).

  What is necessary is just to adjust suitably the temperature hold | maintained at the time of oxidation (henceforth, oxidation temperature) so that a desired oxygen increase rate may be obtained. If the oxidation temperature is low, the ashless coal may be insufficiently oxidized, and the above-described reforming effect may not be sufficiently exhibited. Further, when the oxidation temperature is low, it takes time to achieve a desired oxygen increase rate, and the productivity deteriorates. On the other hand, if the oxidation temperature becomes too high, the oxidation rate becomes too fast, making it difficult to control the degree of oxidation of ashless coal. The oxidation temperature is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, preferably less than the ignition point of ashless coal, more preferably 350 ° C. or lower.

  The oxidation time (retention time at a predetermined temperature) may be appropriately adjusted so that a predetermined oxygen increase rate is obtained. If the oxidation time is short, the ashless coal may become insufficiently oxidized. On the other hand, if the oxidation time is long, ashless coal is excessively oxidized, resulting in a decrease in yield and an increase in cost. For example, the preferred oxidation time in the above temperature range is 0.5 hours or more, more preferably 1 hour or more, preferably 6 hours or less, more preferably 3 hours or less. What is necessary is just to cool to room temperature after oxidation.

  In addition, the particle size (equivalent circle diameter, hereinafter, the same particle size) of ashless coal used for the oxidation treatment is not particularly limited. If the particle size of the ashless coal is too large, the inside of the ashless coal will not be sufficiently oxidized, and melting or the like may occur when dry distillation is performed. On the other hand, if the particle size of ashless coal is too small, the handleability deteriorates. The average particle diameter of ashless coal is preferably 3 mm or less, more preferably 1 mm or less, preferably 0.2 mm or more, more preferably 0.3 mm or more. The maximum particle size is also preferably 3 mm or less, more preferably 1 mm or less, and still more preferably 0.5 mm or less from the viewpoint of promoting oxidation.

<Carbon raw material mixing step: C2>
The carbon raw material mixing step is a step of obtaining a mixture (hereinafter referred to as “mixed carbon raw material”) by mixing the ashless coal, the oxidized ashless coal, and petroleum raw coke.

  Petroleum coke is a facility (coker) for producing light oil by heating distillation residue at high temperature (for example, 500 ° C or higher) in the oil refining process and producing it as a by-product along with light oil. It is. In the present invention, various commercially available known petroleum raw cokes can be used as the petroleum raw coke. Preferred petroleum raw coke has a volatile content of 5 to 20% by mass and a sulfur content of 2 to 5% by mass.

  In the present invention, in order to produce high-purity coke, the mixing ratio of ashless coal in the mixed carbon raw material, and the ashless coal and oxidation-free It is necessary to appropriately control the mixing ratio of ash coal.

(I) Content of ashless coal: 5 to 40 parts by mass When the mixing ratio of ashless coal is too small, the function as a binder is not sufficiently exhibited, and coke becomes powdery. On the other hand, if the mixing ratio of ashless coal is too large, softening and melting caused by ashless coal will be excessive, for example, coke will become a sponge-like porous body, the bulk specific gravity will be low, or the inner wall of the dry distillation apparatus Coke may not be discharged due to adhesion.

  In the present invention, the content of ashless coal is 5 parts by mass or more, preferably 10 parts by mass or more, and 40 masses with respect to a total of 100 parts by mass of ashless coal, oxidized ashless coal, and petroleum raw coke. Part or less, preferably 25 parts by weight or less.

(II) Total content of ashless coal and oxidized ashless coal: 30 to 70 parts by mass As described above, the total amount of ashless coal is 40 parts by mass or less. The amount of raw coke used can be reduced, and the impurity content of further coke can be reduced. Since ashless coal and oxidized ashless coal are more expensive than petroleum raw coke, the unit price of coke increases when their total content increases. On the other hand, if the total content of ashless coal and oxidized ashless coal is too low, a sufficient impurity reduction effect cannot be obtained. Therefore, the total content of ashless coal and oxidized ashless coal is 30 parts by mass or more, preferably 35 parts by mass or more, with respect to 100 parts by mass in total of ashless coal, oxidized ashless coal, and petroleum raw coke. Preferably it is 40 mass parts or more, 70 mass parts or less, Preferably it is 65 mass parts or less, More preferably, it is 60 mass parts or less.

  The content of oxidized ashless coal is not particularly limited, but if the content of oxidized ashless coal is too small, coke expands and becomes sponge-like or melts and becomes stuck in the apparatus. The oxidized ashless coal is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 30 parts by mass or more with respect to 100 parts by mass in total of ashless coal, oxidized ashless coal, and petroleum raw coke. It is. On the other hand, the upper limit of oxidized ashless coal may be appropriately adjusted so as to be within the range of the total content (30 to 70 parts by mass) of the above ashless coal and oxidized ashless coal, but preferably 50 parts by mass or less, More preferably, it is 40 parts by mass or less.

  The average particle size of the ashless coal is not particularly limited, but if the average particle size of the ashless coal is too large, the mixed state of the mixture may be uneven and the binder effect may not be sufficiently exhibited. On the other hand, if the average particle size is too small, the handleability may deteriorate. The average particle size of the ashless coal is preferably 1.0 mm or less, more preferably 0.5 mm or less, preferably 0.1 mm or more, more preferably 0.2 mm or more. The maximum particle size of ashless coal is preferably 1.0 mm or less, more preferably 0.5 mm or less, because if the particle size is too large, the mixed state in the molded product may be uneven.

  Moreover, it is desirable to make the average particle size of ashless coal smaller than the average particle size of oxidized ashless coal, because the gap between carbon raw materials is filled and the binder effect is further enhanced.

  The mixture of the present invention only needs to contain ashless coal, oxidized ashless coal, and petroleum raw coke, and other materials (for example, known binders, additives such as coal pitch, etc.) as long as they do not adversely affect the present invention. ) May be contained, but when other materials are included in the mixture, the impurity content of coke may increase due to the materials. Therefore, the total of ashless coal, oxidized ashless coal, and petroleum raw coke in the mixture is preferably 90% by mass or more, and more preferably 100% by mass. 100% by mass means that the mixture is made of ashless coal, oxidized ashless coal, and petroleum raw coke, and the balance is impurities.

  The mixing method of ashless coal, oxidized ashless coal, and petroleum raw coke is not particularly limited, and a known method for obtaining uniform mixing may be employed. A mixer, a kneader, a single screw mixer, a twin screw Examples of such mixers are illustrated.

<Molding process: C3>
The forming step is a step of obtaining a formed body by forming the mixture obtained in the carbon raw material mixing step (C2) into a desired shape as necessary. By forming the mixture into a molded body, a bond between the carbon raw materials can be formed more firmly due to the binder effect of ashless coal, and coke pulverization and a decrease in bulk specific gravity can be suppressed.

  For example, when carbonizing a mixture in a chamber furnace, a load is applied in the vertical direction, so that the distance between the carbon raw materials becomes close, and the carbon raw materials are combined by the binder effect of ashless coal, so that the coke becomes powdery. The bulk specific gravity can be increased. Such an effect can be further improved by forming a molded body.

  On the other hand, when the mixture is carbonized using a horizontal furnace such as a rotary kiln where a vertical load is not sufficiently applied, the binder effect is not sufficiently exhibited. For this reason, the bonds between the carbon raw materials are weak, the coke tends to become powdery, and the bulk specific gravity of the coke also decreases. Therefore, it is desirable to shape the mixture into a desired shape before dry distillation.

  The method for forming the mixture into a molded body is not particularly limited. For example, in addition to a method using a double roll (double roll) type molding machine using a flat roll, a double roll type molding machine having an almond type pocket, Any method such as a method using a uniaxial press, a roller type molding machine, an extrusion molding machine, or press molding using a mold can be adopted. Among these, it is desirable to form a briquette or sheet shaped body by twin roll briquette or roll compaction.

The mixture may be formed by cold forming at around room temperature, but hot forming by heating is preferred. When the mixture is pressure-molded at a high temperature, the ashless coal is plastically deformed to fill the voids between the oxidized ashless coal particles and petroleum raw coke, and a further compacted compact can be obtained. Therefore, coke having a higher bulk specific gravity can be obtained by dry distillation of the compacted compact. On the other hand, if the molding temperature becomes too high, the ashless coal may soften and expand, and bulk specific gravity may not be achieved. The hot molding temperature (device temperature such as molds and rolls) is preferably 100 ° C. or higher, more preferably 200 ° C. or higher, preferably 450 ° C. or lower, more preferably 300 ° C. or lower. The molding pressure is not particularly limited, and known conditions may be adopted. For example, the molding pressure is about 0.5 to 3 ton / cm ² .

<Dry distillation process: C4>
The dry distillation step is a step of obtaining coke by dry distillation of the mixture obtained in the carbon raw material mixing step (C2) or the molded body obtained in the molding step (C3). The shape of the furnace used for dry distillation is not particularly limited, and batch distillation may be performed using a chamber furnace, or continuous distillation may be performed using a vertical shaft furnace. A horizontal rotary furnace such as a rotary kiln may be used.

  Known conditions can be adopted as the dry distillation conditions, and the dry distillation temperature may be appropriately set and is not particularly limited, but is preferably 650 ° C. or higher, more preferably 700 ° C. or higher, preferably 1200 ° C. or lower, more preferably 1050 ° C. or lower. Temperature is fine. Also, the carbonization time at the carbonization temperature is not particularly limited, and may be a desired carbonization time depending on the apparatus configuration, etc., preferably 5 minutes or more, more preferably 10 minutes or more, preferably 24 hours or less, more preferably It may be 12 hours or less.

  The dry distillation atmosphere may be a non-oxidizing gas atmosphere in order to prevent deterioration due to oxidation of coke. Various known gases can be used as the non-oxidizing gas. For example, an inert gas such as nitrogen, helium, or argon, or a reducing gas such as hydrogen gas may be used.

  Petroleum coke becomes calcine coke by calcining and ashless coal acts as a binder between oxidized ashless coal and calcine coke, and the oxidized ashless coal and calcine coke are firmly bonded. Therefore, the strength of coke is also improved.

  When the mixture is carbonized, the carbon raw materials are bonded to each other, and an indeterminate massive coke is obtained. When the mixture is molded, coke having substantially the same shape as the molded body before dry distillation is obtained. Since the coke of the present invention appropriately controls the blending ratio of ashless coal, the coke does not adhere to the dry distillation apparatus and cannot be discharged, and does not become powdery.

The coke thus obtained has higher purity and higher bulk specific gravity than conventionally known coke. Specifically, the mineral content as an impurity is preferably 1% by mass or less, more preferably 0.5% by mass or less. The bulk specific gravity is preferably 0.53 g / cm ³ or more, more preferably 0.6 g / cm ³ or more, still more preferably 0.7 g / cm ³ or more, and most preferably 0.8 g / cm ³ or more. The sulfur content is preferably 2% by mass or less.

  Further, the above mixture does not cause the above-mentioned problems due to softening and melting properties and expandability at the time of dry distillation, so that the obtained coke has an excellent appearance and can be discharged from the dry distillation apparatus.

  As described above, ashless coal, oxidized ashless coal obtained by oxidizing ashless coal, and petroleum raw coke, a total of 100 masses of ashless coal, oxidized ashless coal, and petroleum raw coke Coke formed by dry-distilling a mixture in which the content of ashless coal is 5 to 40 parts by mass and the total content of ashless coal and oxidized ashless coal is 30 to 70 parts by mass, This is a coke having improved high softness and high bulk density, which improves the softening meltability and expandability, which are problematic when using ash charcoal.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to carry out and they are all included in the technical scope of the present invention.

(Manufacture of ashless coal)
(Slurry heating process: S1)
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.

(Separation step: S2)
The obtained slurry was separated into a supernatant and a solid concentrate in a gravity settling tank maintaining the same temperature and pressure.

(Ashless coal acquisition process: S3)
The obtained supernatant was further filtered (a stainless mesh filter having an opening of 1 μm) to obtain an ashless coal solution. Aromatic solvents were separated and recovered from the ashless coal solution by distillation to produce ashless coal. The obtained ashless coal was pulverized so as to pass through a sieve having an opening of 3 mm to obtain ashless coal.

(Measurement of sulfur content)
About this ashless coal, the sulfur concentration was measured by the method defined in JIS M8122. As a result, the sulfur content of the ashless coal was 0.5% by mass.

  (Manufacture of coke)

(Oxidation step: C1)
A part of the ashless coal was pulverized so as to pass through a sieve having an opening of 0.5 mm. The crushed ashless charcoal was heated to a predetermined temperature shown in Table 1 in an air atmosphere, and kept at the same temperature for a predetermined time for oxidation treatment (“oxidation conditions” in Table 1). After the oxidation treatment, the mixture was allowed to cool to room temperature to obtain oxidized ashless coal. In addition, the oxygen concentration of ashless coal and oxidized ashless coal was measured based on JIS M 8813 before and after the oxidation treatment, and the oxygen increase rate of oxidized ashless coal was calculated. The results are shown in Table 1 (in Table 1, “Oxygen increase rate”).

(Oil raw coke)
Commercial petroleum raw coke (volatile content: 9.5% by mass, sulfur content: 3.1% by mass) was pulverized so as to pass through a sieve having an opening of 10 mm.

(Carbon raw material mixing step: C2)
The ashless coal (“A” in the table), oxidized ashless coal (“B” in the table), and raw petroleum coke (“C” in the table) are given in the predetermined ratios shown in Table 1 ( The mixture was obtained by mixing at the raw material mixing ratio “)”.

  In addition, No. In No. 16, the oxygen increase rate of oxidized ashless coal was less than 2% (1.50%), and it was handled as ashless coal. Therefore, no. The blending ratio of 16 is A: B: C = 50 (20% by mass of ashless coal not subjected to oxidation treatment + 30% by mass of ashless coal with an oxygen increase rate of 1.5%): 0:50. . In order to show the details of the blending ratio of 16, for convenience, the blending ratio (“20”) of ashless coal that has not been oxidized is described in the A column in the table, and the oxygen increasing rate is 1 in the B column. The blending ratio (“30”) of .5% ashless coal was described.

(Molding process: C3)
About some mixtures (No. 7-12, 15; "formation presence / absence" in the table | surface) = there exists), the molded object was manufactured on the following conditions.
Molding method: roll compaction method Roll temperature: 100 ° C
Roll diameter: 162mm
Roll width: 60mm (Ayame groove)
Width between rolls: 2mm
Roll rotation speed: 15rpm
Linear pressure: 3 tons / cm

(Dry distillation process: C4)
Mixtures (Nos. 1-6, 13, 14, 16-25) and molded bodies (Nos. 7-12, 15) can be used as chamber furnaces (No. 1-6, 15-25) or kilns (No. 7). ~ 14) was subjected to dry distillation treatment.

(Distillation treatment in a room furnace)
A graphite crucible with an internal volume of 1000 mL was charged with the mixture (No. 1-6, 16-25) or the molded body (No. 15) so that the bulk specific gravity was 0.85 g / cm ^3, and in a nitrogen atmosphere Coke was produced by heating to 1000 ° C. at a rate of 3 ° C./min and holding at that temperature for 5 hours to dry distillation.

(Crying process using rotary kiln)
The mixture (No. 13, 14) or the molded body (No. 7 to 12) was inserted into a heated rotary kiln (diameter 200 mm, total length 4000 mm) at an insertion speed of 1 kg / 1. The heating temperature of the rotary kiln was adjusted so that the inlet temperature was 400 ° C. and the outlet temperature was 1000 ° C. Coke was produced by holding at that temperature in a nitrogen atmosphere for 60 minutes and dry distillation.

(Evaluation method)
The obtained coke was examined for bulk specific gravity, sulfur content, appearance, and the presence or absence of adhesion in the apparatus.

(Bulk specific gravity) (in the table, “bulk specific gravity after dry distillation (g / cm ³ )”)
Coke was filled into a wooden cube container having a side of 100 mm, and the bulk specific gravity (W × 1000 (g / cm ³ )) was determined from the dry mass (W: g) of the filled coke. In this example, a bulk specific gravity of 0.53 g / cm ³ or more was evaluated as acceptable.

(Sulfur content) (“Sulfur content after dry distillation (%)” in the table)
The coke sulfur concentration was measured in the same manner as ashless coal. In this example, if the coke sulfur content was 2.0% or less, it was evaluated as acceptable.

(Appearance, presence or absence of adhesion in the device) (“Coke properties” in the table)
The appearance of the coke was visually observed and evaluated. When carbonized in a chamber furnace (Nos. 1-6, 15-25): When the coke was in a lump, it was set as “Excellent” (“PE” in the table). Further, when the coke is in a lump shape but slightly expanded (bulk specific gravity of 0.53 or more and less than 0.7 g / cm ³ ), it was determined as “Pass” (“P” in the table). When the coke was powdery, it was evaluated as “Fail” (“F” in the table). In addition, when the coke adhered and could not be discharged (“FA” in the table) or expanded (“FB” in the table), it was evaluated as “Fail”. The evaluation is PE>P> (F, FA, FB).

  When carbonized by kiln (Nos. 7 to 14): When the coke is in the form of flakes and no expansion, cracking, chipping, or pulverization occurs, “pass” (in the table, “ P ”), and in the case of powder, or expansion, cracking, chipping or powdering, it was evaluated as“ Fail ”(“ F ”in the table). Further, when the coke adhered and could not be discharged, it was evaluated as “Fail” (“FA” in the table). Evaluation is P> (F, FA).

  As shown in Table 1, No. 1 satisfying the predetermined requirements of the present invention. The cokes of 2 to 5, 8 to 11, 15, 17 to 21, 23, and 24 had a high purity with a sulfur content of 2.0% or less and a high bulk specific gravity. Moreover, the expansion | swelling etc. at the time of a carbonization process were fully suppressed, and the coke property was also favorable. In addition, No. In No. 5, since the blending ratio of ashless coal was high, the coke expanded slightly. No. Since the oxygen increase rate of No. 17 was lower than the other examples, the modification of oxidized ashless coal was inferior to the other examples, and the coke expanded slightly.

  No. 1 is an example in which the blending ratio of ashless coal was low. In this example, since there was little ashless coal which functions as a binder, coke was pulverized by dry distillation treatment.

  No. 6 is an example in which the blending ratio of ashless coal was high. In this example, since there was much ashless coal, expansion | swelling generate | occur | produced when dry-distilling and coke became sponge-like (porous body), and bulk specific gravity fell remarkably.

  No. 7 is an example in which the blending ratio of ashless coal was low. In this example, since there was little ashless coal, when dry-distilling, it pulverized in the kiln.

  No. 12 is an example in which the blending ratio of ashless coal was high. In this example, ashless coal melted during dry distillation, and the molded body expanded and expanded, so that coke adhered to the inner wall of the kiln and could not be discharged.

  No. 13 is an example in which the mixture was dry-distilled in a kiln without forming the mixture. In this example, since sufficient pressure could not be applied to the mixture during dry distillation, oxidized ashless coal and petroleum coke could not be sufficiently combined, and the coke was powdery.

  No. No. 14 is an example of dry distillation in a kiln as a powder without forming the mixture. In this example, no. As with No. 13, oxidized ashless coal and petroleum raw coke cannot be sufficiently combined. Since the content of ashless coal was increased from 13, the coke adhered to the inner wall of the kiln due to the molten and expanded ashless coal, and could not be discharged.

  No. No. 16 is an example in which the oxygen increase rate was low because the oxidation time was short with respect to the oxidation temperature. This example does not include oxidized ashless coal with an ashless coal oxygen increase rate of 2.0% or more, and ashless coal (ashless coal and oxidized ashless coal with an oxygen increase rate of less than 2.0%) ), The ashless coal expanded and expanded, and the bulk specific gravity decreased.

  No. No. 22 is an example in which the blending ratio of petroleum raw coke is large. In this example, the sulfur content after dry distillation was large and the purity of coke was low.

  No. 25 (Reference Example) is an example in which the blending ratio of petroleum raw coke is small. In this example, a coke having a low sulfur content and a high bulk specific gravity was obtained. However, since the blending ratio of the raw petroleum coke was small, the coke became an expensive coke.

Claims (8)

Ashless charcoal,
Oxidized ashless coal obtained by oxidizing ashless coal,
Including petroleum raw coke,
For a total of 100 parts by mass of the ashless coal, the oxidized ashless coal, and the petroleum raw coke,
Coke production characterized by dry-distilling the mixture whose content of the said ashless coal is 5-40 mass parts, and whose total content of the said ashless coal and the said oxidation ashless coal is 30-70 mass parts Method.   The method for producing coke according to claim 1, wherein the mixture is formed and then carbonized.   The method for producing coke according to claim 1 or 2, wherein the oxygen increase rate of the oxidized ashless coal is 2 to 10%.   The method for producing coke according to claim 1, wherein the oxidation treatment is air oxidation.   The method for producing coke according to any one of claims 1 to 4, wherein the oxidation treatment is performed at a temperature of 150 ° C or higher and lower than an ignition point.   The method for producing coke according to any one of claims 1 to 5, wherein the dry distillation is performed in a chamber furnace.   The method for producing coke according to claim 2, wherein the dry distillation is performed in a rotary kiln. Ashless charcoal,
Oxidized ashless coal obtained by oxidizing ashless coal,
Including petroleum raw coke,
For a total of 100 parts by mass of the ashless coal, the oxidized ashless coal, and the petroleum raw coke,
Coke formed by dry-distilling a mixture in which the content of the ashless coal is 5 to 40 parts by mass and the total content of the ashless coal and the oxidized ashless coal is 30 to 70 parts by mass. .

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