WO2015182529A1 - Method for manufacturing blast furnace coke, and blast furnace coke - Google Patents

Method for manufacturing blast furnace coke, and blast furnace coke Download PDF

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Publication number
WO2015182529A1
WO2015182529A1 PCT/JP2015/064824 JP2015064824W WO2015182529A1 WO 2015182529 A1 WO2015182529 A1 WO 2015182529A1 JP 2015064824 W JP2015064824 W JP 2015064824W WO 2015182529 A1 WO2015182529 A1 WO 2015182529A1
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coal
coke
blast furnace
blended
ashless
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PCT/JP2015/064824
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French (fr)
Japanese (ja)
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濱口　眞基
祥平 和田
一秀 石田
貴洋 宍戸
裕子 西端
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株式会社神戸製鋼所
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Priority to CN201580022691.8A priority Critical patent/CN106232776A/en
Priority to KR1020167032669A priority patent/KR101864524B1/en
Priority to EP15799597.8A priority patent/EP3150687A4/en
Publication of WO2015182529A1 publication Critical patent/WO2015182529A1/en

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
    • C10B57/04—Other carbonising or coking processes; Features of destructive distillation processes in general using charges of special composition
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B57/00—Other carbonising or coking processes; Features of destructive distillation processes in general
    • C10B57/08—Non-mechanical pretreatment of the charge, e.g. desulfurization

Definitions

  • the present invention relates to a method for producing coke for blast furnace and coke for blast furnace.
  • Coke used in ironmaking in a blast furnace has a function as a reducing agent for iron ore (iron oxide), a function as a heat source (fuel), and a breathability in the furnace that can withstand the load between the coke itself and iron ore.
  • Three functions are expected for the function as a filler for ensuring the resistance.
  • the coke is required to have a certain strength and reactivity (reducibility and combustibility).
  • coke is produced by steaming coal at a high temperature of 1000 ° C. or higher (hereinafter sometimes referred to as “dry distillation”).
  • dry distillation When obtaining coke with high strength, so-called strong caking coal having high caking properties is used, but such caking coal is relatively expensive. Therefore, for the purpose of reducing the production cost of coke, in addition to weakly caking coal, which has lower caking properties than strongly caking coal, slightly caking coal with poor caking properties and non-caking coal with almost no caking properties.
  • weakly caking coal which has lower caking properties than strongly caking coal
  • slightly caking coal with poor caking properties and non-caking coal with almost no caking properties hereinafter, a combination of slightly caking coal and non-caking coal may be referred to as “non-caking coal”).
  • non-caking coal a combination of slightly caking coal and non-caking coal.
  • the mechanism by which high-strength coke is generated has been clarified to a considerable extent, and various
  • FIG. 1A is a diagram schematically showing this change
  • the left side shows a state in which coal particles before carbonization (strongly caking coal particles 1 and non-slightly caking coal particles 2) are present in the furnace body 10.
  • the right side shows a state in which the continuous phase 1a formed by expansion of the strongly caking coal particles 1 after dry distillation and the altered component 2a of the non-fine caking coal particles 2 are present.
  • the strongly caking coal particles 1 are melted during the dry distillation process, expand by containing the generated gas, and combine with the adjacent caking coal particles 1 to form a continuous phase 1a containing bubbles A.
  • the ratio of the strong caking coal is a certain level or more and the ratio of the non-minor caking coal is small, the non-minor caking coal particles 2 are taken into the caking coal during the above-described continuous phase formation process, so that defects are hardly generated.
  • the ratio of non-slightly caking coal is high as shown in FIG. 1A, adhesion between the strongly caking coal particles 1 is inhibited, and low-strength coke having coarse defects B inside is generated.
  • the above-described method for producing high-strength coke has the following operational problems or difficulties.
  • the method for increasing the packing density in (1) above is a special method such as highly drying coal, forming a part of the coal to increase the density, or performing mechanical treatment such as stamp charging. Work is required and both are costly. Further, increasing the density of the raw material coal may exert a high pressure on the coke oven wall.
  • the present invention has been made based on the circumstances as described above, and a method for producing coke for blast furnace, which can obtain coke with high strength at low cost while suppressing the influence on the coke oven due to expansion, and for such blast furnace
  • the purpose is to provide coke.
  • the present inventors are an extraction component obtained by solvent extraction treatment of coal, and ashless coal that exhibits high fluidity and expansibility in a molten state is used as a raw material coal. It has been found that, by blending the above, the expansion rate of the blended coal is set to 20% or less, and high-strength blast furnace coke can be obtained while suppressing damage to the coke oven due to expansion of the raw coal.
  • the invention made in order to solve the above problems is for a blast furnace comprising a blending step in which ashless coal obtained by solvent extraction treatment of coal is blended with coal to form blended coal, and a step of dry distillation of the blended coal.
  • a method for producing coke wherein the blending amount of the ashless coal in the blending step is 3% by mass or more and the expansion rate of the blended coal is 20% or less.
  • the method for producing coke for blast furnace is to mix the ashless coal with coal in the blending amount in the above range, and this ashless coal melts during dry distillation and fills the gaps in the raw coal. Can be increased. Moreover, the manufacturing method of the said coke for blast furnaces can suppress the influence on the coke oven by expansion
  • the “expansion coefficient” is a value measured according to JIS-M8801: 2004.
  • ⁇ Expansion rate of blended coal in the blending step should be 10% or more.
  • the expansion rate of blended coal 10% or more the generation of coarse defects during dry distillation can be suppressed, and the strength of the resulting coke can be further increased.
  • the coal blended with the above ashless coal may include strong caking coal and non-slightly caking coal, and the proportion of the strong caking coal in the blended coal is preferably 20% by mass or more and 50% by mass or less.
  • strong caking coal generally means that the average maximum reflectance Ro is 1.3% or more and 1.6% or less, and the logarithm (log MF) of the maximum fluidity MF (ddpm) is 0.8 or more and 2.5 or less. Or, Ro is 1.0% or more and 1.3% or less and log MF is 1.5 or more and 4 or less.
  • Non-slightly caking coal is a general term for micro-caking coal and non-caking coal.
  • Ro is less than 0.85 and log MF is 2.5 or less, or Ro is 0.85 or more and log MF is Means 2 or less coal.
  • the “average maximum reflectance Ro” is a value measured in accordance with JIS-M8816: 1992
  • the “maximum fluidity MF” is in accordance with the JIS-M8801: 2004 Guiseller plastometer method. Is a measured value.
  • Another invention made in order to solve the above-mentioned problems is a blast furnace coke obtained by dry distillation of coal blended with ashless coal obtained by solvent extraction treatment of coal in coal,
  • the blending amount of ash coal is 3% by mass or more, and the expansion rate of the blended coal is 20% or less.
  • the blast furnace coke can be manufactured at a low cost while suppressing the influence on the coke oven due to expansion while having high strength for the reasons described above.
  • the blast furnace coke production method of the present invention can provide low-cost and high-strength blast furnace coke while suppressing the influence of expansion on the coke oven.
  • Such blast furnace coke can be suitably used as an iron-making material.
  • the method for producing blast furnace coke includes a step of blending ashless coal obtained by solvent extraction treatment of coal with coal (a blending step) and a step of dry distillation of the blended coal (dry distillation step).
  • ⁇ Mixing process> In the blending step, ashless coal is blended with coal, which is a raw material for coke, to obtain blended coal.
  • Coal used as a raw material for coke in the method for producing coke for blast furnace is not particularly limited. They can be used in combination at an appropriate ratio that enables the entire fusion.
  • the raw coal may include strongly caking coal and non-caking coal.
  • the upper limit of the ratio of the strong caking coal in the raw material coal is preferably 50% by mass and more preferably 40% by mass from the viewpoint of producing high-quality coke at a lower cost.
  • the ratio of strong caking coal in raw material coal is preferred and 30 mass% is more preferred.
  • the ratio of strong caking coal exceeds the said upper limit, there exists a possibility that the manufacturing cost of coke may increase.
  • the ratio of strong caking coal is less than the said minimum, there exists a possibility that the intensity
  • the raw material coal is preferably finely pulverized granular.
  • average particle diameter D20 of raw material coal 3 mm or less is preferable.
  • average particle diameter D20 exceeds 3 mm, there exists a possibility that the mixability with ashless coal and the intensity
  • the “average particle size D20” is the average particle size of the particles remaining on the sieve when all the particles are sieved in order from the largest mesh sieve using a metal mesh sieve defined in JIS-Z8801-1: 2006. It means the size of the sieve mesh when the cumulative volume is 20% of the total particle volume.
  • the raw coal may be dry coal by air drying or the like, but may be one containing moisture.
  • Ashless coal (Hypercoal, HPC) is a type of modified coal obtained by modifying coal, and is a modified coal obtained by removing as much ash and insoluble components as possible from coal using a solvent.
  • the ashless coal may contain ash as long as the fluidity and expansibility of the ashless coal are not significantly impaired.
  • coal contains ash content of 7% by mass or more and 20% by mass or less, but ashless coal used in the method for producing the blast furnace coke may contain ash content of about 2%, and in some cases, about 5%.
  • “Ash” means a value measured in accordance with JIS-M8812: 2004.
  • Such ashless coal is a solvent extraction process in which coal is mixed with a solvent having a high affinity with the coal to obtain an extract from which components insoluble in solvents such as ash are separated, and the solvent is removed from the extract. Can be obtained.
  • the solvent extraction treatment for example, the method disclosed in Japanese Patent No. 4405229 can be used.
  • Ashless coal obtained by such solvent extraction treatment is substantially free of ash, contains many organic substances that are soluble in the solvent and exhibit softening and melting properties, and has two or three condensed aromatic rings structurally. From a relatively low molecular weight component to a high molecular weight component having about 5 or 6 condensed aromatic rings. Therefore, ashless coal exhibits high fluidity under heating and generally melts at 150 ° C.
  • ashless coal expands while producing a large amount of volatile components in the initial stage of dry distillation at about 300 ° C. or more and 500 ° C. or less.
  • the water content is about 0.2% by mass or more and 3% by mass or less and has a sufficient calorific value.
  • ashless coal is excellent in heat fluidity and has high caking properties, so that the caking properties of non-fine caking coal can be compensated.
  • ashless coal particles 4 are dispersed and blended with raw coal particles (strongly caking coal particles 1 and non-slightly caking coal 2), thereby making ashless coal in a coke oven.
  • the particles 4 start to flow at a temperature lower than that of the raw coal particles, and the continuous phase 4a derived from the ashless coal particles 4 is formed substantially uniformly including the center portion of the coke oven where the temperature rise is slow.
  • the continuous phase 1a originating in the strongly caking coal particle 1 and the altered component 2a of the non-slightly caking carbon particle 2 are connected, and the space
  • the lower limit of the blending amount of ashless coal in this blending step is 3% by weight, more preferably 4% by weight, and even more preferably 5% by weight.
  • an upper limit of the compounding quantity of ashless coal 15 mass% is preferable, 12 mass% is more preferable, and 10 mass% is further more preferable.
  • the lower limit of 3% by mass can be calculated as follows. First, the porosity at the time of dry distillation of raw coal not containing ashless coal is approximately 10% by volume. Whether this void can be filled with ashless coal is a problem. Here, ashless coal has a remarkably higher fluidity in the molten state than ordinary coal, and therefore, the expansion rate measurement by the JIS method cannot be applied. Therefore, the expansion rate of ashless coal is measured by the following method.
  • a quartz test tube having an inner diameter of 15 mm is filled with 1.8 g of anthracite pulverized to a particle size of 2 mm or less and 0.2 g of ashless coal pulverized to a particle size of 200 ⁇ m or less, and heat-treated to 500 ° C. at 3 ° C./min. Then, the expansion coefficient V 10% (%) is obtained from the ratio of the height of the sample after heating to the height of the sample before heating.
  • Anthracite coal has the highest degree of coalification among coals, and is often used as a part of raw material coal for producing iron-making coke, but has no caking or fluidity. This is the reason why anthracite is used in the above measurement method, that is, since anthracite does not melt or expand during the carbonization process, ashless coal is mixed with coal particles and carbonized. This is because it is expected that the expansion rate in the process can be estimated with higher accuracy.
  • the quality of the coal used as the raw material for the ashless coal used in the method for producing the blast furnace coke is not particularly limited.
  • the ashless coal is preferably in the form of particles having a small particle size from the viewpoint of increasing dispersibility and increasing the strength of coke.
  • the upper limit of the maximum diameter of ashless coal particles is preferably 1 mm. When the maximum diameter of ashless coal particles exceeds the above range, the above-described coal particle connection effect cannot be obtained sufficiently, and the strength of coke may be insufficient.
  • the maximum diameter of the ashless coal particles means the maximum length (maximum distance between two points) of the outer shape of the ashless coal particles taken with an electron microscope or the like, for example.
  • the lower limit of the logarithm (log MF) of the maximum fluidity of blended coal in which ashless coal is blended with raw coal is preferably 1.8, more preferably 2, and even more preferably 2.1.
  • the upper limit of the log MF of the coal blend is preferably 3, more preferably 2.5, and even more preferably 2.3.
  • the maximum fluidity MF mainly indicates the thermal fluidity
  • the log MF of the blended coal means a value obtained by weighted averaging of the log MFs of all coal and ashless coal contained in the raw coal.
  • the upper limit of the average maximum reflectance Ro of the blended coal is preferably 1.3, and more preferably 1.2.
  • the average maximum reflectance Ro of blended coal is less than the above lower limit, expansion and fusion of the coal or ashless coal is insufficient due to the low degree of coalification of the blended coal, and the strength of the obtained coke is low. May be sufficient.
  • the average maximum reflectance Ro of the blended coal exceeds the above upper limit, the expansion rate becomes too high, which may affect the furnace body.
  • the average maximum reflectance Ro mainly indicates the degree of coalification, and Ro of blended coal means a value obtained by weighted averaging of Ro of all coal and ashless coal contained in raw coal.
  • the upper limit of the coefficient of expansion of the blended coal is 20%, preferably 19%, and more preferably 18%.
  • the lower limit of the coefficient of expansion of the blended coal is preferably 10%, more preferably 12%, and even more preferably 14%.
  • the expansion rate of the blended coal blend exceeds the above upper limit, the coke oven may be damaged due to the expansion of the coal blend.
  • the expansion rate of the blended coal is less than the above lower limit, the expansion and fusion of the coal or ashless coal may be insufficient, and the strength of the resulting coke may be insufficient.
  • the expansion rate of blended coal is not a weighted average of the expansion rates of coal and ashless coal contained in the blended coal. It is difficult to predict.
  • the blending method of the ashless coal to the raw coal is not particularly limited, and for example, a method in which the raw coal and the ashless coal are respectively introduced into a known mixer from a hopper and stirred while being pulverized by a conventional method can be used. .
  • a method in which the raw coal and the ashless coal are respectively introduced into a known mixer from a hopper and stirred while being pulverized by a conventional method can be used.
  • secondary particles in which ashless coal is aggregated can be pulverized and raw material coal can be pulverized into granules.
  • pre-ground coal and ashless coal may be mixed.
  • a binder other than ashless coal may be added to the raw coal, but in the method for producing the coke, coal particles are connected by ashless coal as described above, so it is necessary to add a binder. There is no. Therefore, it is preferable that blended coal does not contain binders other than ashless coal from a viewpoint of cost reduction.
  • coke is obtained by charging the blended coal into a coke oven and performing carbonization.
  • a coke oven for example, one having a furnace body capable of charging about 30 tons per gate can be used.
  • the lower limit of the packing density of instrumentation Nyutoki to coke ovens coal blend preferably 720kg / m 3, 730kg / m 3 and more preferably.
  • the upper limit of the packing density is preferably 850kg / m 3, 800kg / m 3 and more preferably.
  • the filling density exceeds the upper limit, the pressure applied to the furnace body is increased and the furnace body may be damaged, or the production cost of coke may be increased by the work of improving the filling density of the blended coal.
  • “Filling density” means a bulk density measured in accordance with JIS-K2151: 2004.
  • 950 As a lower limit of the dry distillation temperature of the blended coal, 950 ° C is preferable, and 1000 ° C is more preferable. On the other hand, as an upper limit of dry distillation temperature, 1200 degreeC is preferable and 1050 degreeC is more preferable. When the dry distillation temperature is less than the above lower limit, coal may not be sufficiently melted and coke strength may be reduced. On the other hand, when the dry distillation temperature exceeds the above upper limit, the production cost may increase from the viewpoint of heat resistance of the furnace body and fuel consumption.
  • the lower limit of the carbonization time of the blended coal 8 hours is preferable and 10 hours is more preferable.
  • the upper limit of the carbonization time is preferably 24 hours, more preferably 20 hours.
  • the carbonization time is less than the above lower limit, the coal is not sufficiently melted and the strength of the coke may be reduced.
  • the carbonization time exceeds the above upper limit, the production cost may increase from the viewpoint of fuel consumption.
  • the method for producing the blast furnace coke is blended with coal so that the blending amount of ashless coal is in the above range, so that the ashless coal melts during dry distillation and fills the gaps in the raw coal. Strength can be increased. Moreover, the manufacturing method of the said coke for blast furnaces can suppress the influence on the coke oven by expansion
  • the blast furnace coke of the present invention is obtained by dry-distilling coal blended with coal containing ashless coal obtained by coal solvent extraction treatment.
  • the blending amount of the ashless coal in the blended coal and the expansion rate of the blended coal are set in the ranges described above. Therefore, the blast furnace coke has high strength at a low cost.
  • Ashless coal was produced by the following method using a hypercall continuous production facility (Bench Scale Unit). First, Australian bituminous coal is used as raw material coal for ashless coal, and 5 kg (dry coal equivalent mass) of this raw material coal is mixed with 4-fold amount (20 kg) of 1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.) as a solvent. A slurry was prepared. This slurry was put into a batch type autoclave having an internal volume of 30 L, nitrogen was introduced, the pressure was increased to 1.2 MPa, and the mixture was heated at 370 ° C. for 1 hour.
  • Bench Scale Unit Hypercall continuous production facility
  • the slurry is separated into a supernatant and a solid concentrate in the gravity settling tank maintaining the above temperature and pressure, and the solvent is separated and recovered from the supernatant by distillation to obtain 2.7 kg of ashless Charcoal F was obtained.
  • the obtained ashless coal F had an ash content of 0.9% by mass, the logarithm log MF of the maximum fluidity and the average maximum reflectance Ro were as shown in Table 1.
  • the ashless coal F was pulverized so that all (100% by mass) had a maximum diameter of 3 mm or less.
  • the maximum fluidity MF was calculated from the blending ratio of each raw material coal and ashless coal. Further, the expansion ratio of the blended coal was measured in accordance with JIS-M8801: 2004. These values are shown in Table 2.
  • the blended charcoal was put in a steel retort, adjusted to the packing density shown in Table 2 by applying vibration to the retort, and then placed in a double-sided heating electric furnace and dry-distilled in a nitrogen stream. As the dry distillation conditions, the temperature was raised at 3 ° C./min and then heated at 1000 ° C. for 20 minutes. After dry distillation, the retort was removed from the electric furnace and allowed to cool naturally to obtain blast furnace coke.
  • the drum strength index DI was measured for the blast furnace cokes of Examples 1 to 4 and Comparative Examples 1 to 11. Specifically, in accordance with JIS-K2151: 2004, blast furnace coke is rotated 150 times with a drum, and then sorted with a metal plate sieve having an opening of 15 mm as defined in JIS-Z8801-2: 2006. The mass ratio (DI15015) of the remaining blast furnace coke was determined. Moreover, the pass criterion of intensity
  • the blast furnace coke of Examples 1 to 4 blended with 3% by mass or more of ashless coal has a drum strength index DI of 84.5% or more and high strength. Since the expansion rate is 20% or less, damage to the coke oven is prevented. Furthermore, Examples 1 to 4 are excellent in manufacturing cost because the packing density is relatively small at 740 kg / m 3 .
  • the blast furnace coke of Comparative Example 1 having a high proportion of strongly caking coal is excellent in strength, but the expansion rate of the blended coal is as high as 34%, which may damage the coke oven.
  • the blast furnace coke of Comparative Examples 2, 6, and 7 in which the ratio of non-slightly caking coal is increased, but the expansion rate of the blended coal is small, but the strength is insufficient.
  • the coke for blast furnace of Comparative Example 3 in which the ratio of the highly expandable strong caking coal A is increased, although high strength is obtained, the expansion rate of the blended coal is as high as 26%, and the coke oven may be damaged. It is expensive because a large amount of strong caking coal A is used.
  • the blast furnace coke of Comparative Example 4 having an increased filling density has sufficient strength and is less likely to damage the coke oven, but a cost increase is inevitable because a filling process is required.
  • the coke for blast furnace of Comparative Example 5 in which the packing density is increased is insufficient in strength and, like Comparative Example 4, an increase in cost is inevitable.
  • the blast furnace coke of Comparative Example 8 is blended with ashless coal, its blending amount is less than 3% by mass, so that sufficient strength cannot be secured.
  • the blast furnace coke of Comparative Examples 9 to 11 also contains ashless coal, the expansion rate of the strong caking coal G is very high, so the expansion rate of the coal blend is also high. Increased risk of damage.
  • the blast furnace coke production method of the present invention can provide low-cost and high-strength blast furnace coke while suppressing the influence of expansion on the coke oven.
  • Such blast furnace coke can be suitably used as an iron-making material.

Abstract

　This method for manufacturing blast furnace coke is provided with a step for blending, with coal, ashless coal obtained by solvent extraction processing of coal, and a step for carbonizing the blended coal, the blended amount of the ashless coal in the blending step being 3% by mass or greater, and the expansion coefficient of the blended coal being 20% or lower.

Description

高炉用コークスの製造方法及び高炉用コークスMethod for producing blast furnace coke and blast furnace coke
　本発明は、高炉用コークスの製造方法及び高炉用コークスに関する。 The present invention relates to a method for producing coke for blast furnace and coke for blast furnace.
　高炉での製鉄で使用されるコークスには、鉄鉱石（酸化鉄）の還元材としての機能、熱源（燃料）としての機能、及びコークス自体と鉄鉱石との荷重に耐えて炉内の通気性を確保するための充填材としての機能の大きくは３つの機能が期待される。これらの機能を果たすため、上記コークスには一定の強度と反応性（還元性及び燃焼性）とが求められる。 Coke used in ironmaking in a blast furnace has a function as a reducing agent for iron ore (iron oxide), a function as a heat source (fuel), and a breathability in the furnace that can withstand the load between the coke itself and iron ore. Three functions are expected for the function as a filler for ensuring the resistance. In order to fulfill these functions, the coke is required to have a certain strength and reactivity (reducibility and combustibility).
　一般に、コークスは石炭を１０００℃ないしそれ以上の高温で蒸し焼きにする（以下、「乾留する」ということがある。）ことにより製造される。強度の高いコークスを得る場合、粘結性の高い、いわゆる強粘結炭が使用されるが、このような強粘結炭は比較的高価である。そのため、コークスの製造コストの低減を目的として、強粘結炭よりも粘結性の低い弱粘結炭に加え、粘結性に乏しい微粘結炭や粘結性のほとんど無い非粘結炭（以下、微粘結炭と非粘結炭とをあわせて「非微粘結炭」ということがある。）もコークス原料として一定量配合される。高強度のコークスが生成するメカニズムはかなりの程度明らかになっており、高強度コークスを効率的に得るための方法が種々提案されている（例えば、国際公開第２０１０／１０３８２８号公報参照）。 Generally, coke is produced by steaming coal at a high temperature of 1000 ° C. or higher (hereinafter sometimes referred to as “dry distillation”). When obtaining coke with high strength, so-called strong caking coal having high caking properties is used, but such caking coal is relatively expensive. Therefore, for the purpose of reducing the production cost of coke, in addition to weakly caking coal, which has lower caking properties than strongly caking coal, slightly caking coal with poor caking properties and non-caking coal with almost no caking properties. (Hereinafter, a combination of slightly caking coal and non-caking coal may be referred to as “non-caking coal”). The mechanism by which high-strength coke is generated has been clarified to a considerable extent, and various methods for efficiently obtaining high-strength coke have been proposed (see, for example, International Publication No. 2010/103828).
　ここで、乾留過程での石炭粒子の変化について説明する。図１Ａはこの変化を模式的に表現した図であり、左側が乾留前の石炭粒子（強粘結炭粒子１及び非微粘結炭粒子２）が炉体１０の中に存在する状態を示し、右側が乾留後に強粘結炭粒子１が膨張して形成された連続相１ａと非微粘結炭粒子２の変質成分２ａとが存在する状態を示す。強粘結炭粒子１は乾留過程で溶融し、発生するガスを内包して膨張し、隣接する強粘結炭粒子１と結合することで気泡Ａを含む連続相１ａを形成する。強粘結炭の割合が一定以上で非微粘結炭の割合が小さい場合には、非微粘結炭粒子２は上記連続相形成過程で強粘結炭に取り込まれるため、欠陥は生じにくい。ところが、図１Ａのように非微粘結炭の割合が高い場合、強粘結炭粒子１同士の接着が阻害され、内部に粗大欠陥Ｂをもつ強度の低いコークスが生成する。 Here, the change of coal particles during the carbonization process will be explained. FIG. 1A is a diagram schematically showing this change, and the left side shows a state in which coal particles before carbonization (strongly caking coal particles 1 and non-slightly caking coal particles 2) are present in the furnace body 10. The right side shows a state in which the continuous phase 1a formed by expansion of the strongly caking coal particles 1 after dry distillation and the altered component 2a of the non-fine caking coal particles 2 are present. The strongly caking coal particles 1 are melted during the dry distillation process, expand by containing the generated gas, and combine with the adjacent caking coal particles 1 to form a continuous phase 1a containing bubbles A. When the ratio of the strong caking coal is a certain level or more and the ratio of the non-minor caking coal is small, the non-minor caking coal particles 2 are taken into the caking coal during the above-described continuous phase formation process, so that defects are hardly generated. . However, when the ratio of non-slightly caking coal is high as shown in FIG. 1A, adhesion between the strongly caking coal particles 1 is inhibited, and low-strength coke having coarse defects B inside is generated.
　これに対し、コークスの強度を高める方策の一つとして（１）原料石炭の充填密度を通常より高くする方法がある（図１Ｂ参照）。このように充填密度を高めて粒子間の距離を小さくすることで、膨張する強粘結炭により空隙が充填され、欠陥の少ない高強度コークスが生成できる。また、（２）高膨張性の強粘結炭を配合することによっても、コークスの強度を改善できる（図１Ｃ参照）。すなわち、膨張率の極めて大きな高膨張性強粘結炭粒子３を配合することにより、その膨張により非微粘結炭粒子２間に押圧力が作用し、また、粒子空隙がこの高膨張性強粘結炭粒子３に由来する連続相３ａで効果的に充填されるため、コークス強度が改善される。 On the other hand, as one of measures for increasing the strength of coke, there is (1) a method of increasing the packing density of raw material coal than usual (see FIG. 1B). By increasing the packing density and reducing the distance between the particles in this way, the voids are filled with the expanding strong caking coal, and high strength coke with few defects can be generated. Moreover, the intensity | strength of coke can be improved also by mix | blending (2) highly expansible strong caking coal (refer FIG. 1C). That is, by blending the highly expandable strongly caking coal particles 3 with an extremely large expansion rate, a pressing force acts between the non-slightly caking coal particles 2 due to the expansion, and the particle voids are strongly expanded. Since it is effectively filled with the continuous phase 3a derived from the caking coal particles 3, the coke strength is improved.
　ところが、上述の高強度コークスの製造方法は、以下のような操業上の問題、あるいは困難性を有する。まず、上記（１）の充填密度を高める方法は、石炭を高度に乾燥させること、石炭の一部を成形して高密度化させること、スタンプチャージなどの機械的処理を行うこと等の特殊な作業が必要であり、いずれもコストがかかる。また、原料石炭を高密度にすることはコークス炉壁に高い圧力を及ぼすおそれがある。 However, the above-described method for producing high-strength coke has the following operational problems or difficulties. First, the method for increasing the packing density in (1) above is a special method such as highly drying coal, forming a part of the coal to increase the density, or performing mechanical treatment such as stamp charging. Work is required and both are costly. Further, increasing the density of the raw material coal may exert a high pressure on the coke oven wall.
　次に、（２）高膨張性の強粘結炭を使用する方法は、過剰な膨張が発生することにより、コークス炉壁の損傷や破壊、コークス炉からのコークスの排出の困難化等の予測できない操業上のトラブルを発生させる確率が高まるおそれがある。このような（２）の方法の問題点を改善する対策として、（３）タール等の粘結剤を使用することによって石炭の溶融状態での粘性を抑える方法（日本国特開２００１－２１４１７１号公報参照）や、（４）非微粘結炭の膨張率を制御する方法（日本国特開２００８－１５６６６１号公報参照）が提案されている。しかしながら、（３）の方法では粘結剤の添加によるコークスの製造コストの増加が避けられない。また、（４）の方法では、石炭の配合工程が複雑化し、コークスの製造コストが増加し得る。 Next, (2) the method of using highly expandable strong coking coal predicts damage and destruction of the coke oven wall, difficulty in discharging coke from the coke oven, etc. due to excessive expansion. There is a risk of increasing the probability of generating operational trouble that cannot be performed. As a measure for improving the problem of the method (2), (3) a method for suppressing the viscosity of coal in a molten state by using a binder such as tar (Japanese Patent Laid-Open No. 2001-214171). And a method for controlling the expansion rate of non-slightly caking coal (see Japanese Patent Application Laid-Open No. 2008-156661) has been proposed. However, in the method (3), an increase in coke production cost due to the addition of a binder is inevitable. In the method (4), the coal blending process becomes complicated, and the production cost of coke can be increased.
国際公開第２０１０／１０３８２８号公報International Publication No. 2010/103828 日本国特開２００１－２１４１７１号公報Japanese Unexamined Patent Publication No. 2001-214171 日本国特開２００８－１５６６６１号公報Japanese Unexamined Patent Publication No. 2008-156661
　本発明は、上述のような事情に基づいてなされたものであり、膨張によるコークス炉への影響を抑えつつ低コストで高強度のコークスが得られる高炉用コークスの製造方法及びそのような高炉用コークスの提供を目的とする。 The present invention has been made based on the circumstances as described above, and a method for producing coke for blast furnace, which can obtain coke with high strength at low cost while suppressing the influence on the coke oven due to expansion, and for such blast furnace The purpose is to provide coke.
　本発明者らは、上記課題を解決するため鋭意検討した結果、石炭の溶剤抽出処理により得られる抽出成分であり、溶融状態で高い流動性及び膨張性を示す無灰炭を原料石炭に一定値以上配合することで配合炭の膨張率を２０％以下として、原料石炭の膨張によるコークス炉の損傷等を抑制しつつ、高強度の高炉用コークスを得られることを見出した。 As a result of intensive studies to solve the above-mentioned problems, the present inventors are an extraction component obtained by solvent extraction treatment of coal, and ashless coal that exhibits high fluidity and expansibility in a molten state is used as a raw material coal. It has been found that, by blending the above, the expansion rate of the blended coal is set to 20% or less, and high-strength blast furnace coke can be obtained while suppressing damage to the coke oven due to expansion of the raw coal.
　すなわち、上記課題を解決するためになされた発明は、石炭の溶剤抽出処理により得られる無灰炭を石炭に配合して配合炭とする配合工程、及び上記配合炭を乾留する工程を備える高炉用コークスの製造方法であって、上記配合工程における上記無灰炭の配合量を３質量％以上、かつ配合炭の膨張率を２０％以下とすることを特徴とする。 That is, the invention made in order to solve the above problems is for a blast furnace comprising a blending step in which ashless coal obtained by solvent extraction treatment of coal is blended with coal to form blended coal, and a step of dry distillation of the blended coal. A method for producing coke, wherein the blending amount of the ashless coal in the blending step is 3% by mass or more and the expansion rate of the blended coal is 20% or less.
　当該高炉用コークスの製造方法は、上記範囲の配合量で無灰炭を石炭に配合することで、この無灰炭が乾留時に溶融し原料石炭の隙間を充填するため、得られるコークスの強度を高めることができる。また、当該高炉用コークスの製造方法は、配合炭の膨張率を上記範囲とすることで、配合炭の膨張によるコークス炉への影響を抑制することができる。さらに、この配合炭の膨張率の調整は、無灰炭の配合によって容易に達成することができるため、当該高炉用コークスの製造方法では他の粘結剤等を必要としない。その結果、当該高炉用コークスの製造方法は、炉体の長寿命化を図りつつ低コストで高強度の高炉用コークスを得ることができる。なお、「膨張率」とは、ＪＩＳ－Ｍ８８０１：２００４に準拠して測定される値である。 The method for producing coke for blast furnace is to mix the ashless coal with coal in the blending amount in the above range, and this ashless coal melts during dry distillation and fills the gaps in the raw coal. Can be increased. Moreover, the manufacturing method of the said coke for blast furnaces can suppress the influence on the coke oven by expansion | swelling of a combination coal by making the expansion coefficient of a combination coal into the said range. Furthermore, since the adjustment of the expansion rate of the blended coal can be easily achieved by blending ashless coal, no other binder or the like is required in the method for producing coke for blast furnace. As a result, the blast furnace coke manufacturing method can obtain low-cost and high-strength blast furnace coke while extending the life of the furnace body. The “expansion coefficient” is a value measured according to JIS-M8801: 2004.
　上記配合工程における配合炭の膨張率を１０％以上とするとよい。このように配合炭の膨張率を１０％以上とすることで、乾留時の粗大な欠陥の発生を抑制し、得られるコークスの強度をさらに高めることができる。 ¡Expansion rate of blended coal in the blending step should be 10% or more. Thus, by making the expansion rate of blended coal 10% or more, the generation of coarse defects during dry distillation can be suppressed, and the strength of the resulting coke can be further increased.
　上記無灰炭を配合する石炭が強粘結炭及び非微粘結炭を含むとよく、上記配合炭における強粘結炭の割合としては２０質量％以上５０質量％以下が好ましい。強粘結炭の割合をこのような範囲とすることで、低コストで高強度の高炉用コークスをより容易かつ確実に得ることができる。なお、「強粘結炭」とは、一般に平均最大反射率Ｒｏが１．３％以上１．６％以下かつ最高流動度ＭＦ（ｄｄｐｍ）の対数（ｌｏｇＭＦ）が０．８以上２．５以下、あるいはＲｏが１．０％以上１．３％以下かつｌｏｇＭＦが１．５以上４以下の石炭を意味する。「非微粘結炭」とは、一般に微粘結炭及び非粘結炭の総称であり、例えばＲｏが０．８５未満かつｌｏｇＭＦが２．５以下、あるいはＲｏが０．８５以上かつｌｏｇＭＦが２以下の石炭を意味する。ここで、「平均最大反射率Ｒｏ」は、ＪＩＳ－Ｍ８８１６：１９９２に準拠して測定される値であり、「最高流動度ＭＦ」は、ＪＩＳ－Ｍ８８０１：２００４のギーセラープラストメータ法に準拠して測定される値である。 The coal blended with the above ashless coal may include strong caking coal and non-slightly caking coal, and the proportion of the strong caking coal in the blended coal is preferably 20% by mass or more and 50% by mass or less. By setting the ratio of strong caking coal within such a range, low-cost and high-strength blast furnace coke can be obtained more easily and reliably. In addition, “strongly caking coal” generally means that the average maximum reflectance Ro is 1.3% or more and 1.6% or less, and the logarithm (log MF) of the maximum fluidity MF (ddpm) is 0.8 or more and 2.5 or less. Or, Ro is 1.0% or more and 1.3% or less and log MF is 1.5 or more and 4 or less. “Non-slightly caking coal” is a general term for micro-caking coal and non-caking coal. For example, Ro is less than 0.85 and log MF is 2.5 or less, or Ro is 0.85 or more and log MF is Means 2 or less coal. Here, the “average maximum reflectance Ro” is a value measured in accordance with JIS-M8816: 1992, and the “maximum fluidity MF” is in accordance with the JIS-M8801: 2004 Guiseller plastometer method. Is a measured value.
　上記課題を解決するためになされた別の発明は、石炭の溶剤抽出処理により得られる無灰炭を石炭に配合した配合炭を乾留してなる高炉用コークスであって、上記配合炭における上記無灰炭の配合量が３質量％以上、かつ配合炭の膨張率が２０％以下であることを特徴とする。 Another invention made in order to solve the above-mentioned problems is a blast furnace coke obtained by dry distillation of coal blended with ashless coal obtained by solvent extraction treatment of coal in coal, The blending amount of ash coal is 3% by mass or more, and the expansion rate of the blended coal is 20% or less.
　当該高炉用コークスは、上述の理由により、高い強度を有しながら、膨張によるコークス炉への影響を抑えつつ低コストで製造できる。 The blast furnace coke can be manufactured at a low cost while suppressing the influence on the coke oven due to expansion while having high strength for the reasons described above.
　以上説明したように、本発明の高炉用コークスの製造方法は、膨張によるコークス炉への影響を抑えつつ低コストで高強度の高炉用コークスが得られる。このような高炉用コークスは、製鉄材料として好適に用いることができる。 As described above, the blast furnace coke production method of the present invention can provide low-cost and high-strength blast furnace coke while suppressing the influence of expansion on the coke oven. Such blast furnace coke can be suitably used as an iron-making material.
無灰炭を用いない従来のコークスの製造方法における石炭の乾留前後の状態を説明する模式図である。It is a schematic diagram explaining the state before and behind carbonization of the coal in the manufacturing method of the conventional coke which does not use ashless coal. 無灰炭を用いない従来の他のコークスの製造方法（充填密度を高める方法）における石炭の乾留前後の状態を説明する模式図である。It is a schematic diagram explaining the state before and behind dry distillation of coal in the other conventional method for producing coke without using ashless coal (method for increasing packing density). 無灰炭を用いない従来の更に他のコークスの製造方法（強粘着炭を配合する方法）における石炭の乾留前後の状態を説明する模式図である。It is a schematic diagram explaining the state before and after dry distillation of coal in the conventional still another method for producing coke without using ashless coal (method of blending strong coking coal). 無灰炭を配合した石炭の乾留前後の状態を説明する模式図である。It is a schematic diagram explaining the state before and behind dry distillation of the coal which mix | blended ashless coal.
　以下、本発明に係る高炉用コークスの製造方法及び高炉用コークスの実施形態について説明する。  Hereinafter, an embodiment of a method for producing blast furnace coke and a blast furnace coke according to the present invention will be described.
［高炉用コークスの製造方法］ 
　当該高炉用コークスの製造方法は、石炭の溶剤抽出処理により得られる無灰炭を石炭に配合する工程（配合工程）、及び上記配合炭を乾留する工程（乾留工程）を備える。  [Manufacturing method of coke for blast furnace]
The method for producing blast furnace coke includes a step of blending ashless coal obtained by solvent extraction treatment of coal with coal (a blending step) and a step of dry distillation of the blended coal (dry distillation step).
＜配合工程＞ 
　配合工程において、無灰炭をコークスの原料である石炭に配合し、配合炭を得る。  <Mixing process>
In the blending step, ashless coal is blended with coal, which is a raw material for coke, to obtain blended coal.
（石炭）
　当該高炉用コークスの製造方法でコークスの原料として用いる石炭は特に限定されず、強粘結炭、準強粘結炭、弱粘結炭、微粘結炭、非粘結炭等を乾留により石炭全体の融着が可能となる適度な割合で組み合わせて用いることができる。特に、原料石炭は強粘結炭及び非微粘結炭を含むとよい。 (coal)
Coal used as a raw material for coke in the method for producing coke for blast furnace is not particularly limited. They can be used in combination at an appropriate ratio that enables the entire fusion. In particular, the raw coal may include strongly caking coal and non-caking coal.
　原料石炭における強粘結炭の割合の上限としては、より安価に高品質のコークスを製造する観点から、５０質量％が好ましく、４０質量％がより好ましい。一方、原料石炭における強粘結炭の割合の下限としては、２０質量％が好ましく、３０質量％がより好ましい。強粘結炭の割合が上記上限を超える場合、コークスの製造コストが増大するおそれがある。逆に、強粘結炭の割合が上記下限未満の場合、得られるコークスの強度が不十分となるおそれがある。 The upper limit of the ratio of the strong caking coal in the raw material coal is preferably 50% by mass and more preferably 40% by mass from the viewpoint of producing high-quality coke at a lower cost. On the other hand, as a minimum of the ratio of strong caking coal in raw material coal, 20 mass% is preferred and 30 mass% is more preferred. When the ratio of strong caking coal exceeds the said upper limit, there exists a possibility that the manufacturing cost of coke may increase. On the contrary, when the ratio of strong caking coal is less than the said minimum, there exists a possibility that the intensity | strength of the coke obtained may become inadequate.
　原料石炭は、微細に粉砕された粒状とすることが好ましい。原料石炭を粒状とする場合、原料石炭の平均粒子径Ｄ２０としては３ｍｍ以下が好ましい。平均粒子径Ｄ２０が３ｍｍを超える場合、無灰炭との混合性や、得られるコークスの強度が不十分となるおそれがある。なお、「平均粒子径Ｄ２０」とは、全粒子をＪＩＳ－Ｚ８８０１－１：２００６に規定される金属製網篩で目の大きな篩から順に篩分けした際に、篩の上に残った粒子の累積体積が全粒子の体積の２０％になったときの篩の目の大きさを意味する。 The raw material coal is preferably finely pulverized granular. When making raw material coal granular, as average particle diameter D20 of raw material coal, 3 mm or less is preferable. When average particle diameter D20 exceeds 3 mm, there exists a possibility that the mixability with ashless coal and the intensity | strength of the coke obtained may become inadequate. The “average particle size D20” is the average particle size of the particles remaining on the sieve when all the particles are sieved in order from the largest mesh sieve using a metal mesh sieve defined in JIS-Z8801-1: 2006. It means the size of the sieve mesh when the cumulative volume is 20% of the total particle volume.
　なお、原料石炭は、風乾等により乾燥炭としてもよいが、水分を含んだ状態のものを用いてもよい。 Note that the raw coal may be dry coal by air drying or the like, but may be one containing moisture.
（無灰炭）
　無灰炭（ハイパーコール、ＨＰＣ）は、石炭を改質した改質炭の一種であり、溶剤を用いて石炭から灰分と非溶解性成分とを可能な限り除去した改質炭である。しかしながら、無灰炭の流動性や膨張性を著しく損ねない範囲で、無灰炭は灰分を含んでもよい。一般に石炭は７質量％以上２０質量％以下の灰分を含むが、当該高炉用コークスの製造方法に用いる無灰炭においては２％程度、場合によっては５％程度の灰分を含んでもよい。なお、「灰分」とは、ＪＩＳ－Ｍ８８１２：２００４に準拠して測定される値を意味する。 (Ashless coal)
Ashless coal (Hypercoal, HPC) is a type of modified coal obtained by modifying coal, and is a modified coal obtained by removing as much ash and insoluble components as possible from coal using a solvent. However, the ashless coal may contain ash as long as the fluidity and expansibility of the ashless coal are not significantly impaired. In general, coal contains ash content of 7% by mass or more and 20% by mass or less, but ashless coal used in the method for producing the blast furnace coke may contain ash content of about 2%, and in some cases, about 5%. “Ash” means a value measured in accordance with JIS-M8812: 2004.
　このような無灰炭は、石炭をこの石炭と親和性の高い溶剤に混合し、灰分等の溶剤に不溶な成分を分離した抽出液を得て、この抽出液から溶剤を除去する溶剤抽出処理により得ることができる。溶剤抽出処理の具体的な方法としては、例えば日本国特許第４０４５２２９号公報に開示された方法を用いることができる。このような溶剤抽出処理で得られる無灰炭は、実質的に灰分を含まず、溶剤に可溶で軟化溶融性を示す有機物を多く含有し、構造的には縮合芳香環が２又は３環の比較的低分子量の成分から縮合芳香環が５又は６環程度の高分子量の成分まで広い分子量分布を有する。そのため、無灰炭は、加熱下で高い流動性を示し、その原料とした石炭の品質に関わらず一般的に１５０℃以上３００℃以下で溶融する。加えて、無灰炭は、３００℃以上５００℃以下程度の乾留初期過程で多量の揮発分を生成しながら膨張する。また、無灰炭は、石炭と溶剤との混合物（スラリー）の脱水を経て得られるため、水分が０．２質量％以上３質量％以下程度であり、発熱量を十分に有する。 Such ashless coal is a solvent extraction process in which coal is mixed with a solvent having a high affinity with the coal to obtain an extract from which components insoluble in solvents such as ash are separated, and the solvent is removed from the extract. Can be obtained. As a specific method of the solvent extraction treatment, for example, the method disclosed in Japanese Patent No. 4405229 can be used. Ashless coal obtained by such solvent extraction treatment is substantially free of ash, contains many organic substances that are soluble in the solvent and exhibit softening and melting properties, and has two or three condensed aromatic rings structurally. From a relatively low molecular weight component to a high molecular weight component having about 5 or 6 condensed aromatic rings. Therefore, ashless coal exhibits high fluidity under heating and generally melts at 150 ° C. or more and 300 ° C. or less regardless of the quality of the coal used as the raw material. In addition, ashless coal expands while producing a large amount of volatile components in the initial stage of dry distillation at about 300 ° C. or more and 500 ° C. or less. Moreover, since ashless coal is obtained through dehydration of a mixture (slurry) of coal and a solvent, the water content is about 0.2% by mass or more and 3% by mass or less and has a sufficient calorific value.
　このように無灰炭は、熱流動性に優れると共に粘結性が高いため、非微粘結炭の粘結性を補填することができる。具体的には、図２に示すように、無灰炭粒子４を原料石炭粒子（強粘結炭粒子１及び非微粘結炭２）に分散配合することで、コークス炉内で無灰炭粒子４が原料石炭粒子よりも低い温度で流動し始め、温度上昇の遅いコークス炉中心部も含めて無灰炭粒子４に由来する連続相４ａが略均一に形成される。これにより、強粘結炭粒子１に由来する連続相１ａ及び非微粘結炭粒子２の変質成分２ａが連結され、粒子間の空隙が充填される。さらに無灰炭は膨張性が強粘結炭よりも高いために、大きな荷重がかかるコークス炉の下部においても無灰炭粒子４が膨張することで石炭粒子が連結され粒子間の空隙が充填される。その結果、コークスの破壊の起点になり得る石炭粒子間の接着不良（マクロな亀裂）や過剰膨張（粗大な気孔）の発生等の欠陥が軽減され、コークス炉内の位置によるコークスの品質のばらつきを抑制することができる。一方で、無灰炭の溶融状態の粘度は強粘結炭に比べて小さいため、原料石炭に無灰炭を配合した配合炭の膨張率は過度に大きくならない。そのため、無灰炭を配合することで、配合炭の膨張率の増加抑制とコークスの強度向上とを両立することができる。このように無灰炭を粘結剤として用いることで、コークス炉の寿命を延長させながら、高強度の高炉用コークスを低コストで得ることができる。 As described above, ashless coal is excellent in heat fluidity and has high caking properties, so that the caking properties of non-fine caking coal can be compensated. Specifically, as shown in FIG. 2, ashless coal particles 4 are dispersed and blended with raw coal particles (strongly caking coal particles 1 and non-slightly caking coal 2), thereby making ashless coal in a coke oven. The particles 4 start to flow at a temperature lower than that of the raw coal particles, and the continuous phase 4a derived from the ashless coal particles 4 is formed substantially uniformly including the center portion of the coke oven where the temperature rise is slow. Thereby, the continuous phase 1a originating in the strongly caking coal particle 1 and the altered component 2a of the non-slightly caking carbon particle 2 are connected, and the space | gap between particle | grains is filled. Furthermore, since ashless coal has a higher expansibility than strongly caking coal, the coal particles are connected by filling the voids between the particles by expanding the ashless coal particles 4 even in the lower part of the coke oven where a large load is applied. The As a result, defects such as poor adhesion between the coal particles (macro cracks) and excessive expansion (coarse pores) that can be the starting point of coke destruction are reduced, and the coke quality varies depending on the location in the coke oven. Can be suppressed. On the other hand, since the viscosity of the molten state of ashless coal is smaller than that of strongly caking coal, the expansion rate of the blended coal in which ashless coal is blended with the raw coal is not excessively increased. Therefore, by blending ashless coal, it is possible to achieve both suppression of an increase in the coefficient of expansion of the blended coal and improvement in coke strength. By using ashless coal as a binder in this way, high strength blast furnace coke can be obtained at low cost while extending the life of the coke oven.
　本配合工程における無灰炭の配合量の下限としては、３質量％であり、４質量％がより好ましく、５質量％がさらに好ましい。一方、無灰炭の配合量の上限としては、１５質量％が好ましく、１２質量％がより好ましく、１０質量％がさらに好ましい。無灰炭の配合量が上記下限未満の場合、上述した石炭粒子の連結効果が十分得られず、コークスの強度が不十分となるおそれがある。逆に、無灰炭の配合量が上記上限を超える場合、配合炭の膨張率が高くなり過ぎ炉体に影響を与えるおそれがあるほか、コークスの製造コストが増大する。 The lower limit of the blending amount of ashless coal in this blending step is 3% by weight, more preferably 4% by weight, and even more preferably 5% by weight. On the other hand, as an upper limit of the compounding quantity of ashless coal, 15 mass% is preferable, 12 mass% is more preferable, and 10 mass% is further more preferable. When the blending amount of ashless coal is less than the above lower limit, the above-described coal particle connection effect cannot be obtained sufficiently, and the strength of coke may be insufficient. Conversely, when the blending amount of ashless coal exceeds the above upper limit, the expansion rate of the blended coal becomes too high, which may affect the furnace body, and the production cost of coke increases.
　なお、上記下限の３質量％は以下のように算出できる。まず、無灰炭を含まない原料石炭を乾留した際の空隙率はおおよそ１０体積％である。この空隙を無灰炭が満たすことができるかどうかが問題となる。ここで無灰炭は、溶融状態での流動性が通常の石炭に比べて著しく高いため、ＪＩＳ法による膨張率測定は適用できない。そこで、無灰炭の膨張率は以下の方法で測定される。まず、内径１５ｍｍの石英試験管に、粒径２ｍｍ以下に粉砕した無煙炭１．８ｇと、粒径２００μｍ以下に粉砕した無灰炭０．２ｇとを詰め、３℃／ｍｉｎで５００℃まで加熱処理し、加熱前の試料の高さに対する加熱後の試料の高さの比から膨張率Ｖ１０％（％）を求める。つぎに、同じく内径１５ｍｍの石英試験管に、粒径２ｍｍ以下に粉砕した無煙炭１．６ｇと、粒径２００μｍ以下に粉砕した無灰炭０．４ｇとを詰め、３℃／ｍｉｎで５００℃まで加熱処理し、加熱前の試料の高さに対する加熱後の試料の高さの比から膨張率Ｖ２０％（％）を求める。無灰炭の膨張率Ｄ（％）は下記式（１）で求められる。 
　Ｄ＝（Ｖ２０％－Ｖ１０％）／（２０－１０）×１００（％） ・・・（１）  The lower limit of 3% by mass can be calculated as follows. First, the porosity at the time of dry distillation of raw coal not containing ashless coal is approximately 10% by volume. Whether this void can be filled with ashless coal is a problem. Here, ashless coal has a remarkably higher fluidity in the molten state than ordinary coal, and therefore, the expansion rate measurement by the JIS method cannot be applied. Therefore, the expansion rate of ashless coal is measured by the following method. First, a quartz test tube having an inner diameter of 15 mm is filled with 1.8 g of anthracite pulverized to a particle size of 2 mm or less and 0.2 g of ashless coal pulverized to a particle size of 200 μm or less, and heat-treated to 500 ° C. at 3 ° C./min. Then, the expansion coefficient V 10% (%) is obtained from the ratio of the height of the sample after heating to the height of the sample before heating. Next, 1.6 g of anthracite pulverized to a particle diameter of 2 mm or less and 0.4 g of ashless coal pulverized to a particle diameter of 200 μm or less are packed in a quartz test tube having an inner diameter of 15 mm and up to 500 ° C. at 3 ° C./min. Heat treatment is performed, and an expansion coefficient V 20% (%) is obtained from the ratio of the height of the sample after heating to the height of the sample before heating. The expansion coefficient D (%) of ashless coal is obtained by the following formula (1).
D = (V 20% -V 10% ) / (20-10) × 100 (%) (1)
　この方法で測定された無灰炭の膨張率は、無灰炭の原料や製造条件にもよるが、およそ３００％程度（２００％以上５００％以下）である。従って、空隙の大部分、例えば空隙の８０％を充填するのに必要な無灰炭の体積は、１０×０．８／３００×１００％＝２．６体積％となる。無灰炭の比重と原料石炭の比重とは略同じと見なせるため、上記空隙を充填するための無灰炭の質量割合は３質量％とされる。なお、上記測定方法で無煙炭を使用する理由は以下による。無煙炭は、石炭のうちでも石炭化度がもっとも高い部類のものであり、製鉄コークス製造用原料石炭の一部としてしばしば使用されるが、粘結性や流動性を全く持たない。上記測定方法で無煙炭を使用するのはまさにそれが理由であり、すなわち、無煙炭は乾留過程で溶融したり、膨張したりすることがないため、無灰炭が石炭粒子と混合されて乾留される過程での膨張率をより高い精度で推定できると期待されるからである。 The expansion rate of ashless coal measured by this method is about 300% (200% or more and 500% or less), although it depends on the raw material and production conditions of ashless coal. Therefore, the volume of ashless coal required to fill most of the voids, for example 80% of the voids, is 10 × 0.8 / 300 × 100% = 2.6 vol%. Since the specific gravity of the ashless coal and the specific gravity of the raw material coal can be regarded as substantially the same, the mass ratio of the ashless coal for filling the voids is 3% by mass. The reason for using anthracite in the above measurement method is as follows. Anthracite coal has the highest degree of coalification among coals, and is often used as a part of raw material coal for producing iron-making coke, but has no caking or fluidity. This is the reason why anthracite is used in the above measurement method, that is, since anthracite does not melt or expand during the carbonization process, ashless coal is mixed with coal particles and carbonized. This is because it is expected that the expansion rate in the process can be estimated with higher accuracy.
　当該高炉用コークスの製造方法に用いる無灰炭の原料となる石炭については、特に品質を問わない。また、無灰炭は分散性を高めコークスの強度を大きくする観点から粒径の小さい粒子状であることが好ましい。無灰炭粒子の最大径の上限としては、１ｍｍが好ましい。無灰炭粒子の最大径が上記範囲を超える場合、上述した石炭粒子の連結効果が十分得られず、コークスの強度が不十分となるおそれがある。なお、無灰炭粒子の最大径とは、例えば電子顕微鏡等で撮影した無灰炭粒子の外形の最大長さ（２点間の最大距離）を意味する。 The quality of the coal used as the raw material for the ashless coal used in the method for producing the blast furnace coke is not particularly limited. The ashless coal is preferably in the form of particles having a small particle size from the viewpoint of increasing dispersibility and increasing the strength of coke. The upper limit of the maximum diameter of ashless coal particles is preferably 1 mm. When the maximum diameter of ashless coal particles exceeds the above range, the above-described coal particle connection effect cannot be obtained sufficiently, and the strength of coke may be insufficient. The maximum diameter of the ashless coal particles means the maximum length (maximum distance between two points) of the outer shape of the ashless coal particles taken with an electron microscope or the like, for example.
（配合炭）
　原料石炭に無灰炭を配合した配合炭の最高流動度の対数（ｌｏｇＭＦ）の下限としては、１．８が好ましく、２がより好ましく、２．１がさらに好ましい。一方、配合炭のｌｏｇＭＦの上限としては、３が好ましく、２．５がより好ましく、２．３がさらに好ましい。配合炭のｌｏｇＭＦが上記下限未満の場合、配合炭の流動度が不足し、得られるコークスの強度が不十分となるおそれがある。逆に、配合炭のｌｏｇＭＦが上記上限を超える場合、流動度が過剰となってコークス内に気泡が発生し易くなるおそれがある。なお、最高流動度ＭＦは熱流動性の大きさを主に示し、配合炭のｌｏｇＭＦは、原料石炭に含まれる全石炭及び無灰炭のｌｏｇＭＦを加重平均した値を意味する。 (Mixed coal)
The lower limit of the logarithm (log MF) of the maximum fluidity of blended coal in which ashless coal is blended with raw coal is preferably 1.8, more preferably 2, and even more preferably 2.1. On the other hand, the upper limit of the log MF of the coal blend is preferably 3, more preferably 2.5, and even more preferably 2.3. When the log MF of the blended coal is less than the above lower limit, the fluidity of the blended coal is insufficient, and the strength of the resulting coke may be insufficient. Conversely, if the log MF of the blended coal exceeds the above upper limit, the fluidity becomes excessive and air bubbles are likely to be generated in the coke. The maximum fluidity MF mainly indicates the thermal fluidity, and the log MF of the blended coal means a value obtained by weighted averaging of the log MFs of all coal and ashless coal contained in the raw coal.
　配合炭の平均最大反射率Ｒｏの下限としては、０．９５が好ましく、１がより好ましい。一方、配合炭の平均最大反射率Ｒｏの上限としては、１．３が好ましく、１．２がより好ましい。配合炭の平均最大反射率Ｒｏが上記下限未満の場合、配合炭の石炭化度の低さに起因して石炭又は無灰炭の膨張及び融着が不十分となり、得られるコークスの強度が不十分となるおそれがある。逆に、配合炭の平均最大反射率Ｒｏが上記上限を超える場合、膨張率が高くなり過ぎ炉体に影響を与えるおそれがある。なお、平均最大反射率Ｒｏは石炭化度を主に示し、配合炭のＲｏは、原料石炭に含まれる全石炭及び無灰炭のＲｏを加重平均した値を意味する。 As a minimum of average maximum reflectance Ro of combination charcoal, 0.95 is preferred and 1 is more preferred. On the other hand, the upper limit of the average maximum reflectance Ro of the blended coal is preferably 1.3, and more preferably 1.2. When the average maximum reflectance Ro of the blended coal is less than the above lower limit, expansion and fusion of the coal or ashless coal is insufficient due to the low degree of coalification of the blended coal, and the strength of the obtained coke is low. May be sufficient. On the contrary, when the average maximum reflectance Ro of the blended coal exceeds the above upper limit, the expansion rate becomes too high, which may affect the furnace body. The average maximum reflectance Ro mainly indicates the degree of coalification, and Ro of blended coal means a value obtained by weighted averaging of Ro of all coal and ashless coal contained in raw coal.
　配合炭の膨張率の上限としては、２０％であり、１９％が好ましく、１８％がより好ましい。一方、配合炭の膨張率の下限としては、１０％が好ましく、１２％がより好ましく、１４％がさらに好ましい。配合炭の膨張率が上記上限を超える場合、配合炭の膨張によるコークス炉の損傷が発生するおそれがある。逆に、配合炭の膨張率が上記下限未満の場合、石炭又は無灰炭の膨張及び融着が不十分となり、得られるコークスの強度が不十分となるおそれがある。なお、石炭の膨張現象は、石炭粒子間の相互作用に影響を受けるため、配合炭の膨張率は、配合炭に含まれる石炭及び無灰炭の膨張率の加重平均とはならず、正確に予測することは困難とされている。 The upper limit of the coefficient of expansion of the blended coal is 20%, preferably 19%, and more preferably 18%. On the other hand, the lower limit of the coefficient of expansion of the blended coal is preferably 10%, more preferably 12%, and even more preferably 14%. When the expansion rate of the coal blend exceeds the above upper limit, the coke oven may be damaged due to the expansion of the coal blend. On the other hand, when the expansion rate of the blended coal is less than the above lower limit, the expansion and fusion of the coal or ashless coal may be insufficient, and the strength of the resulting coke may be insufficient. In addition, since the expansion phenomenon of coal is affected by the interaction between coal particles, the expansion rate of blended coal is not a weighted average of the expansion rates of coal and ashless coal contained in the blended coal. It is difficult to predict.
　原料石炭への無灰炭の配合方法は、特に限定されず、例えば公知のミキサーに原料石炭及び無灰炭をそれぞれホッパーから投入して、常法で粉砕しながら攪拌する方法を用いることができる。この方法を用いることで、無灰炭が凝集した二次粒子を粉砕すると共に、原料石炭を粒状に粉砕することができる。また、予め粉砕した石炭及び無灰炭を混合してもよい。 The blending method of the ashless coal to the raw coal is not particularly limited, and for example, a method in which the raw coal and the ashless coal are respectively introduced into a known mixer from a hopper and stirred while being pulverized by a conventional method can be used. . By using this method, secondary particles in which ashless coal is aggregated can be pulverized and raw material coal can be pulverized into granules. In addition, pre-ground coal and ashless coal may be mixed.
　また、原料石炭に無灰炭以外の粘結剤を添加してもよいが、当該コークスの製造方法では上述のように無灰炭によって石炭粒子が連結されるため、粘結剤を入れる必要性がない。そのため、コスト低減の観点から配合炭が無灰炭以外の粘結剤を含まないことが好ましい。 In addition, a binder other than ashless coal may be added to the raw coal, but in the method for producing the coke, coal particles are connected by ashless coal as described above, so it is necessary to add a binder. There is no. Therefore, it is preferable that blended coal does not contain binders other than ashless coal from a viewpoint of cost reduction.
＜乾留工程＞
　乾留工程において、上記配合炭をコークス炉に装入し乾留することでコークスを得る。このコークス炉としては例えば１門あたり３０ｔｏｎ程度を装入可能な炉体を有するものを用いることができる。 <Dry distillation process>
In the carbonization step, coke is obtained by charging the blended coal into a coke oven and performing carbonization. As this coke oven, for example, one having a furnace body capable of charging about 30 tons per gate can be used.
　配合炭のコークス炉への装入時の充填密度の下限としては、７２０ｋｇ／ｍ３が好ましく、７３０ｋｇ／ｍ３がより好ましい。一方、上記充填密度の上限としては、８５０ｋｇ／ｍ３が好ましく、８００ｋｇ／ｍ３がより好ましい。上記充填密度が上記下限未満の場合、コークスの強度が不十分となるおそれがある。逆に、上記充填密度が上記上限を超える場合、炉体に加わる圧力が高くなり炉体を損傷するおそれや、配合炭の充填密度を向上させる作業によりコークスの製造コストが上昇するおそれがある。なお、「充填密度」とは、ＪＩＳ－Ｋ２１５１：２００４に準拠して測定されるかさ密度を意味する。 The lower limit of the packing density of instrumentation Nyutoki to coke ovens coal blend, preferably 720kg / m 3, 730kg / m 3 and more preferably. On the other hand, the upper limit of the packing density is preferably 850kg / m 3, 800kg / m 3 and more preferably. When the said packing density is less than the said minimum, there exists a possibility that the intensity | strength of coke may become inadequate. On the other hand, when the filling density exceeds the upper limit, the pressure applied to the furnace body is increased and the furnace body may be damaged, or the production cost of coke may be increased by the work of improving the filling density of the blended coal. “Filling density” means a bulk density measured in accordance with JIS-K2151: 2004.
　配合炭の乾留温度の下限としては、９５０℃が好ましく、１０００℃がより好ましい。一方、乾留温度の上限としては、１２００℃が好ましく、１０５０℃がより好ましい。乾留温度が上記下限未満の場合、石炭の溶融が不十分となりコークスの強度が低下するおそれがある。逆に、乾留温度が上記上限を超える場合、炉体の耐熱性や燃料消費の観点から製造コストが上昇するおそれがある。 950 As a lower limit of the dry distillation temperature of the blended coal, 950 ° C is preferable, and 1000 ° C is more preferable. On the other hand, as an upper limit of dry distillation temperature, 1200 degreeC is preferable and 1050 degreeC is more preferable. When the dry distillation temperature is less than the above lower limit, coal may not be sufficiently melted and coke strength may be reduced. On the other hand, when the dry distillation temperature exceeds the above upper limit, the production cost may increase from the viewpoint of heat resistance of the furnace body and fuel consumption.
　配合炭の乾留時間の下限としては、８時間が好ましく、１０時間がより好ましい。一方、乾留時間の上限としては、２４時間が好ましく、２０時間がより好ましい。乾留時間が上記下限未満の場合、石炭の溶融が不十分となりコークスの強度が低下するおそれがある。逆に、乾留時間が上記上限を超える場合、燃料消費の観点から製造コストが上昇するおそれがある。 As the lower limit of the carbonization time of the blended coal, 8 hours is preferable and 10 hours is more preferable. On the other hand, the upper limit of the carbonization time is preferably 24 hours, more preferably 20 hours. When the carbonization time is less than the above lower limit, the coal is not sufficiently melted and the strength of the coke may be reduced. On the contrary, when the carbonization time exceeds the above upper limit, the production cost may increase from the viewpoint of fuel consumption.
＜利点＞
　当該高炉用コークスの製造方法は、無灰炭の配合量が上記範囲となるよう石炭に配合することで、この無灰炭が乾留時に溶融し原料石炭の隙間を充填するため、得られるコークスの強度を高めることができる。また、当該高炉用コークスの製造方法は、配合炭の膨張率を上記範囲とすることで、配合炭の膨張によるコークス炉への影響を抑制することができる。さらに、この配合炭の膨張率の調整は、無灰炭の配合によって容易に達成することができるため、当該高炉用コークスの製造方法では他の粘結剤等を必要としない。その結果、当該高炉用コークスの製造方法は、炉体の長寿命化を図りつつ低コストで高強度の高炉用コークスを得ることができる。 <Advantages>
The method for producing the blast furnace coke is blended with coal so that the blending amount of ashless coal is in the above range, so that the ashless coal melts during dry distillation and fills the gaps in the raw coal. Strength can be increased. Moreover, the manufacturing method of the said coke for blast furnaces can suppress the influence on the coke oven by expansion | swelling of a combination coal by making the expansion coefficient of a combination coal into the said range. Furthermore, since the adjustment of the expansion rate of the blended coal can be easily achieved by blending ashless coal, no other binder or the like is required in the method for producing coke for blast furnace. As a result, the blast furnace coke manufacturing method can obtain low-cost and high-strength blast furnace coke while extending the life of the furnace body.
［高炉用コークス］
　本発明の高炉用コークスは、石炭の溶剤抽出処理により得られる無灰炭を石炭に配合した配合炭を乾留してなる。当該高炉用コークスは、上記配合炭における上記無灰炭の配合量及び配合炭の膨張率がそれぞれ上述した範囲とされる。そのため、当該高炉用コークスは低コストながら高い強度を有する。 [Coke for blast furnace]
The blast furnace coke of the present invention is obtained by dry-distilling coal blended with coal containing ashless coal obtained by coal solvent extraction treatment. In the blast furnace coke, the blending amount of the ashless coal in the blended coal and the expansion rate of the blended coal are set in the ranges described above. Therefore, the blast furnace coke has high strength at a low cost.
　以下、実施例によって本発明をさらに詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
＜無灰炭の製造＞
　ハイパーコール連続製造設備（Ｂｅｎｃｈ　Ｓｃａｌｅ　Ｕｎｉｔ）を用い、以下の方法により無灰炭を製造した。まず、オーストラリア産瀝青炭を無灰炭の原料石炭とし、この原料石炭５ｋｇ（乾燥炭換算質量）と、溶剤としての４倍量（２０ｋｇ）の１－メチルナフタレン（新日鉄化学社製）とを混合して、スラリーを調製した。このスラリーを内容積３０Ｌのバッチ式オートクレーブ中に入れ窒素を導入して１．２ＭＰａに加圧し、３７０℃で１時間加熱した。このスラリーを上述の温度及び圧力を維持した重力沈降槽内で上澄液と固形分濃縮液とに分離し、上澄液から蒸留法で溶剤を分離及び回収して、２．７ｋｇの無灰炭Ｆを得た。得られた無灰炭Ｆは、灰分が０．９質量％であり、最高流動度の対数ｌｏｇＭＦ及び平均最大反射率Ｒｏが表１に示す通りであった。この無灰炭Ｆをその全て（１００質量％）が最大径３ｍｍ以下になるように粉砕した。 <Manufacture of ashless coal>
Ashless coal was produced by the following method using a hypercall continuous production facility (Bench Scale Unit). First, Australian bituminous coal is used as raw material coal for ashless coal, and 5 kg (dry coal equivalent mass) of this raw material coal is mixed with 4-fold amount (20 kg) of 1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.) as a solvent. A slurry was prepared. This slurry was put into a batch type autoclave having an internal volume of 30 L, nitrogen was introduced, the pressure was increased to 1.2 MPa, and the mixture was heated at 370 ° C. for 1 hour. The slurry is separated into a supernatant and a solid concentrate in the gravity settling tank maintaining the above temperature and pressure, and the solvent is separated and recovered from the supernatant by distillation to obtain 2.7 kg of ashless Charcoal F was obtained. The obtained ashless coal F had an ash content of 0.9% by mass, the logarithm log MF of the maximum fluidity and the average maximum reflectance Ro were as shown in Table 1. The ashless coal F was pulverized so that all (100% by mass) had a maximum diameter of 3 mm or less.
＜実施例１～４及び比較例８＞
　上述のように製造した無灰炭Ｆを用いて、以下の手順で実施例１～４及び比較例８の高炉用コークスを製造した。 <Examples 1 to 4 and Comparative Example 8>
Using the ashless coal F produced as described above, cokes for blast furnaces of Examples 1 to 4 and Comparative Example 8 were produced by the following procedure.
（配合工程）
　上記無灰炭Ｆ及び表１に示す特性の各種原料石炭をそれぞれ水分７．５質量％に調整し、乾燥炭基準で表２に示す配合にて混合し配合炭を得た。このとき、原料石炭はその全て（１００質量％）が最大径３ｍｍ以下になるように粉砕したものを用いた。なお、表１に示す石炭及び無灰炭の最高流動度ＭＦ（ｄｐｐｍ）は、ＪＩＳ－Ｍ８８０１：２００４に準拠しギーセラープラストメータ法にて測定した。また、平均最大反射率Ｒｏ（％）は、ＪＩＳ－Ｍ８８１６：１９９２に準拠して測定し、膨張率（％）は、ＪＩＳ－Ｍ８８０１：２００４に準拠して測定した。 (Mixing process)
The above ashless coal F and various raw material coals having the characteristics shown in Table 1 were adjusted to a moisture content of 7.5% by mass, respectively, and mixed according to the formulation shown in Table 2 on a dry coal basis to obtain blended coal. At this time, the raw material coal used was pulverized so that all (100% by mass) had a maximum diameter of 3 mm or less. The maximum fluidity MF (dppm) of coal and ashless coal shown in Table 1 was measured by the Gieseler plastometer method in accordance with JIS-M8801: 2004. The average maximum reflectance Ro (%) was measured according to JIS-M8816: 1992, and the expansion coefficient (%) was measured according to JIS-M8801: 2004.
　上記配合炭について、各種原料石炭及び無灰炭のそれぞれの配合比から、最高流動度ＭＦを算出した。さらに、ＪＩＳ－Ｍ８８０１：２００４に準拠して配合炭の膨張率を測定した。これらの値を表２に示す。 For the above blended coal, the maximum fluidity MF was calculated from the blending ratio of each raw material coal and ashless coal. Further, the expansion ratio of the blended coal was measured in accordance with JIS-M8801: 2004. These values are shown in Table 2.
（乾留工程）
　上記配合炭を鋼製のレトルトに並べて入れて、このレトルトに振動を与え表２に示す充填密度に調整した後、両面加熱式電気炉に入れ、窒素気流中で乾留した。乾留条件は、３℃／分で昇温した後、１０００℃で２０分間加熱するものとした。乾留後、レトルトを電気炉から取り出して自然放冷し、高炉用コークスを得た。 (Dry distillation process)
The blended charcoal was put in a steel retort, adjusted to the packing density shown in Table 2 by applying vibration to the retort, and then placed in a double-sided heating electric furnace and dry-distilled in a nitrogen stream. As the dry distillation conditions, the temperature was raised at 3 ° C./min and then heated at 1000 ° C. for 20 minutes. After dry distillation, the retort was removed from the electric furnace and allowed to cool naturally to obtain blast furnace coke.
＜比較例１～７＞
　無灰炭を配合しない点以外は、上記実施例１～４及び比較例８と同様の手順で、表２に示す配合で原料石炭を配合し、この配合炭を乾留することで比較例１～７の高炉用コークスを得た。 <Comparative Examples 1 to 7>
Except for not blending ashless charcoal, in the same procedure as in Examples 1 to 4 and Comparative Example 8 above, blending raw coal with the blending shown in Table 2 and subjecting this blended coal to dry distillation, Comparative Examples 1 to 7 blast furnace coke was obtained.
＜比較例９～１１＞
　上記無灰炭Ｆと同様の手順で得た表１に示す性状の無灰炭Ｍを用いた点、並びに表１に示す上記実施例１～４及び比較例１～８で用いたものとは異なる原料石炭を用いた点以外は、上記実施例１～４及び比較例８と同様の手順で、表２に示す配合で原料石炭を配合し、この配合炭を乾留することで比較例９～１１の高炉用コークスを得た。なお、これらの比較例９～１１は、日本国特開２０１４－０１５５０２号公報に記載の実施例の一部である。 <Comparative Examples 9 to 11>
The point using the ashless coal M having the properties shown in Table 1 obtained in the same procedure as the above ashless coal F, and the ones used in Examples 1 to 4 and Comparative Examples 1 to 8 shown in Table 1 Except for using different raw coals, the raw coals were blended in the same manner as in Examples 1 to 4 and Comparative Example 8 with the blending shown in Table 2, and the blended coals were dry-distilled to produce Comparative Examples 9 to Eleven blast furnace cokes were obtained. These Comparative Examples 9 to 11 are part of the examples described in Japanese Patent Application Laid-Open No. 2014-015502.
＜評価＞
　上記実施例１～４及び比較例１～１１の高炉用コークスについて、ドラム強度指数ＤＩを測定した。具体的には、ＪＩＳ－Ｋ２１５１：２００４に準拠し、高炉用コークスをドラムで１５０回転させた後にＪＩＳ－Ｚ８８０１－２：２００６に規定される目開き１５ｍｍの金属板篩で選別し、篩上に残存した高炉用コークスの質量比（ＤＩ１５０１５）を求めた。また、強度の合格基準はＤＩ＞８４．５％とし、これを満たす高炉用コークスを合格としてＡ、満たさない高炉用コークスを不合格としてＢと評価した。これらの結果を表２に示す。 <Evaluation>
The drum strength index DI was measured for the blast furnace cokes of Examples 1 to 4 and Comparative Examples 1 to 11. Specifically, in accordance with JIS-K2151: 2004, blast furnace coke is rotated 150 times with a drum, and then sorted with a metal plate sieve having an opening of 15 mm as defined in JIS-Z8801-2: 2006. The mass ratio (DI15015) of the remaining blast furnace coke was determined. Moreover, the pass criterion of intensity | strength was set to DI> 84.5%, the blast furnace coke which satisfy | fills this was evaluated as A, and the blast furnace coke which was not satisfied was evaluated as B as disqualified. These results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１に示されるように、無灰炭を３質量％以上配合した実施例１～４の高炉用コークスは、ドラム強度指数ＤＩが８４．５％以上であり高い強度を有すると共に、配合炭の膨張率が２０％以下であるため、コークス炉への損傷が防止される。さらに、実施例１～４は、充填密度が７４０ｋｇ／ｍ３と比較的小さいため、製造コストに優れる。 As shown in Table 1, the blast furnace coke of Examples 1 to 4 blended with 3% by mass or more of ashless coal has a drum strength index DI of 84.5% or more and high strength. Since the expansion rate is 20% or less, damage to the coke oven is prevented. Furthermore, Examples 1 to 4 are excellent in manufacturing cost because the packing density is relatively small at 740 kg / m 3 .
　一方、強粘結炭の割合が高い比較例１の高炉用コークスは強度には優れるが配合炭の膨張率が３４％と高く、コークス炉を損傷させるおそれがある。非微粘結炭の割合を増加した比較例２、６、７の高炉用コークスは、配合炭の膨張率は小さいが強度が不十分である。高膨張性の強粘結炭Ａの割合を高めた比較例３の高炉用コークスは、高い強度が得られるものの、配合炭の膨張率が２６％と高くコークス炉を損傷させるおそれがあるほか、強粘結炭Ａを多く使うため高コストである。充填密度を増加させた比較例４の高炉用コークスは、十分な強度を有しコークス炉に損傷を与えるおそれも小さいが、充填処理が必要となるためコスト上昇が避けられない。同じく充填密度を上昇させた比較例５の高炉用コークスは、強度が不足すると共に、比較例４と同様、コスト上昇が避けられない。比較例８の高炉用コークスは、無灰炭を配合しているものの、その配合量が３質量％未満であるため、十分な強度が確保できていない。比較例９～１１の高炉用コークスも無灰炭を配合しているものの、強粘結炭Ｇの膨張率が非常に高いため、配合炭の膨張率も高く、長期的にみるとコークス炉にダメージを与えるおそれが大きくなる。 On the other hand, the blast furnace coke of Comparative Example 1 having a high proportion of strongly caking coal is excellent in strength, but the expansion rate of the blended coal is as high as 34%, which may damage the coke oven. The blast furnace coke of Comparative Examples 2, 6, and 7 in which the ratio of non-slightly caking coal is increased, but the expansion rate of the blended coal is small, but the strength is insufficient. The coke for blast furnace of Comparative Example 3 in which the ratio of the highly expandable strong caking coal A is increased, although high strength is obtained, the expansion rate of the blended coal is as high as 26%, and the coke oven may be damaged. It is expensive because a large amount of strong caking coal A is used. The blast furnace coke of Comparative Example 4 having an increased filling density has sufficient strength and is less likely to damage the coke oven, but a cost increase is inevitable because a filling process is required. Similarly, the coke for blast furnace of Comparative Example 5 in which the packing density is increased is insufficient in strength and, like Comparative Example 4, an increase in cost is inevitable. Although the blast furnace coke of Comparative Example 8 is blended with ashless coal, its blending amount is less than 3% by mass, so that sufficient strength cannot be secured. Although the blast furnace coke of Comparative Examples 9 to 11 also contains ashless coal, the expansion rate of the strong caking coal G is very high, so the expansion rate of the coal blend is also high. Increased risk of damage.
　なお、表２の結果からは、ｌｏｇＭＦと膨張率及びドラム強度指数との間には直接的な相関関係がないことがわかる。そのため、ｌｏｇＭＦを指標として高強度かつ低コストでコークス炉への影響の小さい高炉用コークスを得ることは困難である。 The results in Table 2 show that there is no direct correlation between log MF, expansion coefficient, and drum strength index. For this reason, it is difficult to obtain coke for blast furnace with high strength, low cost and small influence on the coke oven using logMF as an index.
　本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。
　本出願は、２０１４年５月２８日出願の日本特許出願（特願２０１４－１１０１５９）に基づくものであり、その内容はここに参照として取り込まれる。 Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on May 28, 2014 (Japanese Patent Application No. 2014-110159), the contents of which are incorporated herein by reference.
　以上説明したように、本発明の高炉用コークスの製造方法は、膨張によるコークス炉への影響を抑えつつ低コストで高強度の高炉用コークスが得られる。このような高炉用コークスは、製鉄材料として好適に用いることができる。 As described above, the blast furnace coke production method of the present invention can provide low-cost and high-strength blast furnace coke while suppressing the influence of expansion on the coke oven. Such blast furnace coke can be suitably used as an iron-making material.
１　強粘結炭粒子
１ａ　連続相
２　非微粘結炭粒子
２ａ　変質成分
３　高膨張性強粘結炭粒子
３ａ　連続相
４　無灰炭粒子
４ａ　連続相
１０　炉体
Ａ　気泡
Ｂ　粗大欠陥 DESCRIPTION OF SYMBOLS 1 Strong caking coal particle 1a Continuous phase 2 Non-slightly caking carbon particle 2a Alteration component 3 High expansion | swelling strong caking coal particle 3a Continuous phase 4 Ashless coal particle 4a Continuous phase 10 Furnace A Bubble B Coarse defect

Claims (4)

  1. 　石炭の溶剤抽出処理により得られる無灰炭を石炭に配合して配合炭とする配合工程、及び、
    　上記配合炭を乾留する工程 
    を備える高炉用コークスの製造方法であって、 
    　上記配合工程における上記無灰炭の配合量を３質量％以上、かつ配合炭の膨張率を２０％以下とすることを特徴とする高炉用コークスの製造方法。     A blending step of blending coal with coal containing ashless coal obtained by solvent extraction treatment of coal, and
    Process of carbonizing the above blended coal
    A method for producing coke for blast furnace comprising:
    A method for producing coke for blast furnace, wherein the blending amount of the ashless coal in the blending step is 3% by mass or more and the expansion rate of the blended coal is 20% or less.
  2. 　上記配合工程における配合炭の膨張率を１０％以上とする請求項１に記載の高炉用コークスの製造方法。 The method for producing coke for blast furnace according to claim 1, wherein an expansion rate of the blended coal in the blending step is 10% or more.
  3. 　上記無灰炭を配合する石炭が強粘結炭及び非微粘結炭を含み、上記配合炭における強粘結炭の割合が２０質量％以上５０質量％以下である請求項１又は請求項２に記載の高炉用コークスの製造方法。 The coal blended with the ashless coal includes strongly caking coal and non-slightly caking coal, and the proportion of the strong caking coal in the blended coal is 20 mass% or more and 50 mass% or less. A method for producing coke for blast furnace as described in 1.
  4. 　石炭の溶剤抽出処理により得られる無灰炭を石炭に配合した配合炭を乾留してなる高炉用コークスであって、 
    　上記配合炭における上記無灰炭の配合量が３質量％以上、かつ配合炭の膨張率が２０％以下であることを特徴とする高炉用コークス。     A blast furnace coke obtained by dry distillation of coal blended with ashless coal obtained by solvent extraction treatment of coal,
    Blast furnace coke, wherein the blending amount of the ashless coal in the blended coal is 3% by mass or more and the expansion rate of the blended coal is 20% or less.
PCT/JP2015/064824 2014-05-28 2015-05-22 Method for manufacturing blast furnace coke, and blast furnace coke WO2015182529A1 (en)

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