JP2012031236A - Method for producing ironmaking coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing ironmaking coke having high reducing performance and high reactivity.SOLUTION: The method includes: sequentially carrying out an extracting step of extracting a soluble component from coal with a solvent, and affording a mixture slurry of a solvent-soluble component and a solvent-insoluble component; a solid-liquid separating step of separating the mixture slurry into the solvent-soluble component and the solvent-insoluble component using a solid-liquid separating means; a solvent-removing step of removing the solvent from the solvent-insoluble component, and affording non-solvent extracted coal; a mixing step of mixing the non-solvent extracted coal with the raw material coal, and affording a mixture; and a carbonizing step of carbonizing the mixture, and affording the highly reactive coke.

Description

  The present invention relates to a method for producing a highly reactive coke used for iron making such as a blast furnace.

  Iron-making coke is usually produced by heat-drying raw coal at around 1000 ° C. This coke is introduced into the blast furnace so that the coke (reducing material) layer and the iron ore layer overlap each other, and hot air is blown from the tuyere to burn the coke. Pig iron can be produced by reducing iron oxide in iron ore.

  Coke for blast furnace is used by being put into the blast furnace, so it is required to have strength that does not crush in the blast furnace, and also functions as a spacer to ensure air permeability in the blast furnace, and has sufficient strength. Need to be. On the other hand, it is known that if coke having high reactivity (reducibility) is used, the reducing material ratio can be reduced and the operation efficiency of the blast furnace can be improved. In particular, reducing the reducing material ratio can contribute to the reduction of greenhouse gas emissions, and therefore, there is a demand for highly reactive coke that can reduce the use of reducing materials.

  As a method for producing blast furnace coke having both high reactivity and strength, for example, in Patent Document 1, a considerable amount of alkaline earth metal or transition metal (hereinafter referred to as “alkaline earth metal etc.”) is mixed with raw coal. A method for producing coke by dry distillation in a coke oven has been proposed.

  Patent Document 2 proposes to spray an aqueous solution containing an alkaline earth metal or the like on coke obtained by carbonizing coal. Specifically, a certain amount of a predetermined alkaline earth metal or the like is mixed with coal containing about 10% of clay mineral mainly composed of silica or alumina, thereby improving the reactivity. Technology is disclosed.

  However, when the clay mineral and the alkaline earth metal coexist during the dry distillation as in Patent Document 1, the catalytic activity is remarkably reduced. Moreover, even if alkaline earth metal etc. are mixed with coke obtained by dry distillation like patent document 2, the added alkaline earth metal etc. react with the clay mineral in coal in a blast furnace, and catalyst activity falls. Resulting in. Therefore, in these technologies, it is necessary to add a large amount of alkaline earth metal etc. in order to maintain the desired catalytic activity, but the addition of a large amount of alkaline earth metal etc. increases the amount of slag discharged from the blast furnace. And may cause problems such as slag blockage, and may adversely affect the heat-resistant bricks on the inner wall of the blast furnace.

  Also, the ash contained in the coal causes troubles such as fouling and slagging in the combustion furnace, and slag clogging in the blast furnace, preventing further efficient use of the coal.

  Accordingly, the present inventors have developed a technology for removing ash from low-grade coal such as non-slightly caking coal and using it as a raw material for coke to make a slurry by mixing coal and a solvent. After extracting the soluble components, using solid-liquid separation means such as a gravity sedimentation tank, solvent soluble components (extracted components) and solvent insoluble components (extracted residues such as inorganic components such as ash and organic components insoluble in solvents) It was proposed to use solvent-extracted coal (ashless coal with an ash concentration of 0.1% by mass or less: HPC) obtained as a coke raw material by solid-liquid separation and then removing the solvent from the solvent-soluble component. (Patent Document 3, Non-Patent Document 1).

  In addition, the present inventors have disclosed a technique for improving the reactivity by adding an alkaline earth metal or the like by ion exchange to the solvent-extracted coal (Patent Document 4).

JP 2003-306681 A JP 2006-206684 A Japanese Patent Laid-Open No. 2005-120185 JP 2009-227730 A

Takahiro Shishido et al., “Coke production technology using hypercall”, Kobe Steel Technical Report, April 2010, p. 62-66

  Although the technique proposed by the present inventors (Patent Document 4) has excellent reactivity, an alkaline earth metal or the like is required as an ion exchange step or additive, and these are the production costs. It was an increase factor. In particular, in recent years, it has been required to provide ironmaking coke having a low cost and high reactivity.

  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 coke for iron making having high reduction performance and high reactivity.

  The production method of the present invention that has achieved the above-described problems includes an extraction step of extracting a soluble component from coal with a solvent to obtain a mixture slurry of a solvent-soluble component and a solvent-insoluble component, and solid-liquid separation of the mixture slurry. A solid-liquid separation step for separating the solvent-soluble component and the solvent-insoluble component using a means, a solvent removal step for removing the solvent from the solvent-insoluble component to obtain a non-solvent extracted coal, the non-solvent extracted coal, and a raw material The gist is to sequentially include a mixing step of mixing charcoal into a mixture and a dry distillation step of carbonizing the mixture to obtain highly reactive coke.

  It is also a preferred embodiment that the non-solvent extracted coal does not contain the solvent-soluble component obtained by the solid-liquid separation step.

  Moreover, it is also a preferable embodiment that the mass ratio of the non-solvent extracted coal and the raw coal in the mixture is 1:99 to 30:70.

  Furthermore, it is also a preferred embodiment that the raw coal is at least one selected from the group consisting of strongly caking coal, semi-caking coal, and slightly caking coal.

  According to the production method of the present invention, iron coke having high reactivity can be produced. In particular, the non-solvent extracted coal used in the production method of the present invention is produced secondarily when producing solvent extracted coal from general coal, and can be supplied at a low cost. In addition to being able to expand resources as a raw coal, it is possible to reduce raw material costs.

FIG. 1 is a flowchart showing a manufacturing process of iron-making coke according to the present invention. FIG. 2 is a schematic flow diagram of a process showing a production process of non-solvent extracted coal used in highly reactive coke. FIG. 3 is a graph showing pore volumes of raw coal, non-solvent extracted coal, and solvent extracted coal.

  The present inventors already add alkaline earth metal or the like by ion exchange to solvent-extracted charcoal (HPC) obtained by solid-liquid separation of the extraction slurry after solvent extraction and removing the solvent from the solvent-soluble component. Although the technology for improving the reactivity is disclosed (Patent Document 3), as a result of further investigation, the solvent is removed from the solvent-insoluble component obtained as a secondary component upon solid-liquid separation. When the non-solvent extracted coal obtained in this way is used as part of the raw coal, it has been found that the reactivity of coke can be improved, and the present invention has been achieved.

  As shown in the examples described later, the present inventors have introduced a raw material coal (Coal-A) that is a raw material used for solvent extraction, a solvent extracted coal (HPC) obtained by removing the solvent after solid-liquid separation, and non- Solvent extracted coal was analyzed. It has been reported that solvent-extracted charcoal is composed of components melted in a solvent, contains almost no ash, and has high softening and melting properties. On the other hand, non-solvent extracted coal shows almost no softening and melting property, but ash (Ash) contained in the coal before extraction and components not melted in the solvent are concentrated, and the catalyst based on the concentrated ash It was found that the effect can be expected.

  As a result of measuring the pore volume of raw coal (Coal-A), solvent-extracted coal, and non-solvent-extracted coal by the mercury intrusion method, as shown in FIG. The pore volume was almost the same, but the pore volume of the non-solvent extracted coal was found to be about twice that of the raw material coal (Coal-A) or solvent extracted coal. This is presumably because the solvent-soluble component was eluted from the raw coal by the solvent.

  And when non-solvent extraction coal was used as a carbonaceous material for coke with other raw coal, it turned out that the pore volume is large and the reactivity improves by the catalytic action of the concentrated ash.

  In the present invention, by using non-solvent extracted coal together with other raw coal as coke raw coal, the coke having sufficient strength can be produced. The non-solvent extracted coal is a residue obtained by removing soluble components from coal with a solvent, as will be described later, but the carbon content is 80% of the concentration of solvent undissolved components (inorganic and organic components) contained in the coal. It is the above coal. In addition, a soluble component is a component which consists only of the organic substance which remove | eliminated the inorganic substance from coal, and may be called ashless coal (hyper coal: HPC).

  As described above, the production method of the present invention is different from the hypercoal utilization technology that has been proposed so far, and uses non-solvent extracted coal (by-product coal) in which ash is concentrated without using hypercoal as a coke raw material. There is a feature in the place. The non-solvent-extracted coal used in the present invention extracts a soluble component from coal with a solvent to form a mixture slurry of a solvent-soluble component and a solvent-imparting component (extraction step), and the obtained mixture slurry is subjected to solid-liquid separation means. It can be obtained by separating into a solvent-soluble component and a solvent-insoluble component (solid-liquid separation step) and removing the solvent from the solvent-insoluble component (solvent removal step). Then, non-solvent extracted coal and raw coal (preferably at least one selected from the group consisting of strongly caking coal, semi-caking coal, and slightly caking coal) are mixed to form a mixture (mixing step), and this mixture Is subjected to dry distillation (dry distillation step), whereby highly reactive coke can be obtained.

  Hereinafter, embodiments of the manufacturing method of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing a manufacturing process of iron-making coke according to the present invention. FIG. 2 is a schematic flow diagram of a process showing a production process of non-solvent extracted coal used in highly reactive coke.

  As shown in FIG. 1, the highly reactive coke production method of the present invention includes a solvent extraction step (S1), a solid-liquid separation step (S2), a solvent removal step (S3), and a mixing step (S4). And carbonization step (S5). Hereinafter, each step will be described.

<Solvent extraction step (S1)>
The extraction step is a step in which coal (raw coal) is brought into contact with a solvent to extract a soluble component from the raw coal into a solvent to obtain a mixture slurry of the solvent soluble component and the solvent insoluble component.

  In FIG. 2, the raw material coal supplied from the coal supply tank and the solvent supplied from the solvent supply tank are mixed and slurried in the slurry preparation tank, and dissolved in the solvent contained in the raw material coal in the extraction tank. A component (solute) is extracted to form a mixture slurry of a solvent-soluble component and a solvent-insoluble component (extraction step).

  As a solvent used for extraction of a soluble component contained in coal, a polar solvent or an aromatic solvent can be used. For example, N-methylpyrrolidone or pyridine is used as the polar solvent. The aromatic solvent is generally a one-ring aromatic compound such as benzene, toluene or xylene, or a two-ring aromatic compound such as naphthalene, methylnaphthalene, dimethylnaphthalene, trimethylnaphthalene or tetrahydronaphthalene (tetralin; registered trademark). An aromatic compound having three or more rings such as a compound and anthracene is used. 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, it is preferable to use a hydrogen non-donating solvent among the polar solvents and aromatic solvents. Examples of the non-hydrogen donating solvent include coal derivatives mainly composed of a bicyclic aromatic compound purified from a coal carbonization product. This non-hydrogen-donating solvent is stable even when heated and has excellent affinity with coal, so the percentage of soluble components extracted into the solvent is high, and it can be easily recovered by methods such as distillation. Is a good solvent. The recovered solvent can be recycled to improve economy. Examples of the hydrogen non-donating solvent include naphthalene, methylnaphthalene, tar light oil, and the like, and a solvent mainly composed of one kind selected from these and a solvent containing two or more kinds can be used.

  Moreover, the solvent used for extraction of a soluble component has a preferable boiling point of 180-330 degreeC (especially 200-250 degreeC). When the boiling point is too low, the extraction rate of soluble components in the extraction process is lowered. Moreover, the required pressure in an extraction process and the solid-liquid separation process mentioned later becomes high. Further, when recovering the solvent, loss due to volatilization increases, and the solvent recovery rate decreases. On the other hand, if the boiling point is too high, it becomes difficult to remove the solvent from the solvent-soluble component or the solvent-insoluble component separated in the solid-liquid separation step described later, or to remove the solvent adhering to the coal. The recovery rate decreases.

  The type of coal used for extraction of soluble components is not particularly limited, but mainly by using cheap coal such as steam coal or non-thin coal with almost no softening and melting property, the economy is improved. be able to. Of course, the present invention is not limited to non-slightly caking coal, and slightly caking coal, semi-slightly caking coal, strongly caking coal, or the like may be used.

  In the extraction step, it is preferable to pulverize the coal to a diameter of about 5 mm or less (preferably 3 mm or less) in order to facilitate extraction of soluble components from the coal.

  Moreover, in the said extraction process, in order to improve the extraction rate when extracting a soluble component from coal, it is preferable to mix coal and a solvent in a slurry form. If this mixture is heated with stirring, soluble components soluble in the solvent contained in the coal are extracted into the solvent.

  For example, the extraction temperature is preferably set to about 300 to 420 ° C. (particularly about 330 to 400 ° C.). If the extraction temperature is too low, the easy gasification component contained in the coal cannot be removed, and it becomes insufficient to weaken the intermolecular bonding force of the component constituting the coal, so that the soluble component contained in the coal is extracted. The rate is lowered. On the other hand, if the extraction temperature is too high, recombination of radicals generated by thermal decomposition of coal occurs, so that the extraction rate when extracting soluble components from coal becomes low.

  The extraction time may be, for example, about 10 to 120 minutes (particularly about 30 to 60 minutes). If the extraction time is too long, the thermal decomposition reaction of the extracted soluble component proceeds and the radical polymerization reaction proceeds, so the extraction rate of the soluble component decreases.

  What is necessary is just to perform an extraction process in presence of inert gas (for example, nitrogen), for example. In addition, it is necessary to pressurize so that a solvent may not boil in an extraction process, and what is necessary is just to adjust a pressure to the range of about 0.8-2.5 MPa (especially 1-2 MPa) normally.

<Solid-liquid separation step S2>
The solid-liquid separation step is a step of separating the slurry treated in the solvent extraction step (S1) into a solvent soluble component and a solvent insoluble component. The solvent-soluble component is mainly composed of a soluble component (extracted component) extracted from coal into a solvent and a solvent used for extraction. The solvent-insoluble component is an extraction residue that is mainly composed of ash and insoluble coal that are insoluble in the solvent, and also includes the solvent used for extraction.

  The solid-liquid separation means is not particularly limited, and a known method may be employed. Examples thereof include various filtration methods, centrifugal separation methods, and gravity sedimentation methods. In the filtration method, since the filtration amount of the filtration filter is limited, a large amount of undissolved coal may not be separated. In the centrifugal separation method, clogging with undissolved coal is likely to occur, and it may be difficult to implement industrially. On the other hand, according to the gravitational sedimentation method, an extract that is mainly liquid can be obtained from the upper part of the gravity sedimentation tank, and an extraction residue that is mainly a solid concentrate can be obtained from the lower part. This is preferable because it is possible and is suitable for a large amount of processing at a low cost.

  In addition, it is preferable to set the temperature of the solvent in a solid-liquid separation process, and the pressure at the time of solid-liquid separation to the same range as the temperature and pressure which were set at the said extraction process. This is to prevent reprecipitation of the solute eluted from the raw material coal.

  In FIG. 2, a mixture slurry of a solvent-soluble component and a solvent-insoluble component is supplied from the extraction step to a gravity floatation tank. In the gravity floatation tank, it is separated into a solvent soluble component and a solvent insoluble component. The solvent-insoluble component settled in the lower part of the gravity settling tank is discharged to the non-extracted charcoal concentrate receiver, and the solvent-soluble component in the upper part is converted into a solvent-soluble component via a filter unit (not shown) as necessary. After removing the solvent-insoluble component contained, it is discharged to the extracted charcoal solution receiver.

<Solvent removal step S3>
A solvent removal process is a process of removing a solvent from the said solvent insoluble component, and obtaining non-solvent extraction charcoal. By removing the solvent from the solvent-insoluble component, it is possible to obtain non-solvent extracted coal in which extraction residues such as ash and undissolved coal are concentrated.

  The ash content means residual inorganic substances (silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, etc.) when incinerated at 815 ° C. In this invention, it is preferable that the content rate of the ash content contained in non-solvent extraction charcoal is about 15-25% on a mass basis.

  As a method for separating the solvent, a general distillation method or evaporation method (spray drying method or the like) can be used. In the present invention, it is preferable to reuse the separated and recovered solvent as a part of the solvent used in the extraction step.

  Similarly, ashless charcoal (HPC) having an extremely low ash content can be obtained by removing the solvent-soluble component using a distillation method or the like. Ashless coal contains almost no inorganic matter contained in the coal (ash content 5000 ppm or less) and is composed of organic matter. However, HPC is not used in the present invention.

<Mixing step S4>
A mixing process is a process which mixes the non-solvent extraction charcoal obtained by removing a solvent from a solvent insoluble component at the said solvent removal process (S3), and raw material charcoal.

  The mixing method of the non-solvent extracted coal and the raw coal is not particularly limited, and a known method that can obtain uniform mixing may be employed. For example, a mixer, a kneader, a single screw mixer, a twin screw mixer, etc. Can be used.

  The type of coal that can be used as the raw coal to be mixed with the non-solvent extracted coal is not particularly limited, but in particular, at least one selected from the group consisting of strongly caking coal, semi-caking coal, and slightly caking coal may be used. desirable. This is because, when these are used as raw coal, reactivity can be improved while suppressing a decrease in strength even when mixed with non-solvent extracted coal.

  In the present invention, the strongly caking coal is a coal having an average maximum reflectance (Ro) of more than 1.1 to 1.5 and a Gieseller fluidity (log MF) of 0.5 to 3.5, and semi-caking coal. , Ro is 0.7 to 1.1 or less, log MF is more than 2.5 to 3.5 coal, slightly caking coal, Ro is 0.7 to 1.1 or less, log MF is 0.5 to 2 .5 or less coal.

  Strongly caking coal, semi-strongly caking coal, and slightly caking coal can also be used in combination of multiple types, and may be combined as appropriate according to the required coke characteristics.

  In general, strong caking coal has high caking properties, and increasing the blending amount of the strong caking coal improves the strength of the resulting coke. Moreover, since semi-strongly caking coal has the viscosity next to strongly caking coal, and has the characteristics of high fluidity and high expansibility, the properties of the blended coal can be controlled by appropriately combining these coals. In addition, although slightly caking coal is inexpensive but has poor meltability and expandability, increasing the blending amount of the slightly caking coal decreases the strength of the coke obtained.

  In the present invention, in order to obtain coke having high reactivity and sufficient strength as a spacer, the ratio of (strongly caking coal and semi-caking coal): slightly caking coal is set to 85:15. The ratio is preferably 40:60, more preferably 80:20 to 50:50.

  The particle size of the raw coal is preferably 70% by mass or more (more preferably 80% by mass or more, and still more preferably 90% by mass or more) of 3 mm or less. If the coal having a particle size exceeding 3 mm exceeds 30% by mass, the strength of the obtained coke may be lowered. In the present invention, the “particle size” is a value obtained by a sieving method, and specifically, a value obtained by a particle size test method (JIS M8801).

  The non-solvent extracted coal is obtained through the above-described process, and the non-solvent extracted coal is a coal having a carbon content of 80% or more which is concentrated by solvent-insoluble components (ash and organic components) contained in the coal. . Further, the Gieseller fluidity (log MF) has a property that cannot be measured because the non-solvent extracted coal does not melt.

  The particle size of the non-solvent extracted coal is not particularly limited, but when the particle size of the non-solvent extracted coal is large, it may cause cracks in the coke. Therefore, the particle size of the non-solvent extracted coal is preferably 1 mm or less (more preferably 0.5 mm or less) when the particle size of the raw coal is in the above range. The lower limit of the particle size of the non-solvent extracted coal is not particularly limited. However, if the particle size is too small, it may adhere to the apparatus, and costs for pulverization occur. 0.10 mm or more).

  The particle size of the non-solvent extracted coal can also be adjusted by changing the conditions in the above production method, but the non-solvent extracted coal obtained in the above step is sieved or separately pulverized. The particle size of the non-solvent extracted coal can be controlled.

  The pore volume of the non-solvent extracted coal is desirably larger than that of the solvent extracted coal or the raw coal. This is because the larger the pore volume, the better the coke reactivity.

  The mixing ratio of the non-solvent extracted coal and the raw coal is not particularly limited. However, if the mixing ratio of the non-solvent extracted coal is too high, the handling property is deteriorated, for example, the strength of the coke is reduced and the coke is crushed in the blast furnace. On the other hand, when the mixing ratio of the non-solvent extracted coal becomes too low, the reactivity improvement effect by the non-solvent extracted coal cannot be sufficiently obtained. Therefore, the mixing ratio of non-solvent extracted coal and raw coal (non-solvent extracted coal: coking coal) is 1:99 to 30:70 (more preferable lower limit is 5:95 or more and more preferable upper limit is 15:85 on a mass basis). Hereinafter, a more preferable upper limit is preferably 10:90 or less.

  In the production of the mixture, known additives and the like may be included as necessary, but the mixture is obtained by using solvent-extracted charcoal obtained by removing the solvent from the solvent-soluble component after solid-liquid separation as a carbon material. Not included. As described above, the solvent-extracted charcoal has a high softening and melting property, acts as a binder, and improves the strength, so that the reactivity may be reduced.

  In the present invention, the above mixture may be formed into a desired shape into a lump. The method for forming the lump is not particularly limited. For example, in addition to a method using a double roll type molding machine using flat rolls, a double roll type molding machine having an almond type pocket, Any method such as a method using a shaft press, a roller type molding machine, or an extrusion molding machine can be adopted.

  The forming of the lump may be cold forming performed at around room temperature or hot forming performed by heating. The hot forming is preferably performed at a temperature exceeding room temperature and not higher than about 400 ° C. When the molding temperature exceeds 400 ° C., coal is thermally decomposed, tar is generated, and the coal components are lost. Preferably, hot forming is performed at about 250 to 350 ° C. The molding pressure is not particularly limited, and known conditions may be adopted.

  For example, using a double-roll type molding machine, heat-press molding may be performed at 200 to 400 ° C. (more preferably 250 to 350 ° C.).

  The size of the lump (molded product) obtained through the molding as described above is approximately 10 to 30 mm, although it varies depending on the type of raw iron ore and coal, production conditions, or operating conditions in a blast furnace.

<Dry distillation process S5>
The dry distillation step is a step of dry distillation of the mixture obtained in the mixing step (S4). The coal portion is coked by dry distillation, and highly reactive coke can be produced.

  The carbonization process can be performed using an existing coke oven. 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. When a vertical shaft furnace is used, the iron ore-containing coke is charged from above the furnace, dry-distilled while moving in the furnace from top to bottom, and dry-distilled from the bottom of the furnace. Is discharged.

  As the carbonization conditions, known conditions can be adopted, the carbonization temperature is about 650 to 1200 ° C. (particularly about 700 to 1100 ° C.), and the carbonization time is about 5 minutes to 24 hours (particularly about 10 minutes to 16 hours). do it. In the dry distillation atmosphere, it is not necessary to flow a non-oxidizing gas in particular. If the furnace is sealed, oxygen is consumed and the coal becomes a volatilizing atmosphere. If necessary, in order to prevent deterioration due to oxidation of coal. A non-oxidizing gas atmosphere may be used.

  The iron coke thus obtained has a sufficient strength and has a higher reactivity than conventional coke.

  As mentioned above, although the manufacturing method of the coke for steel manufacture which concerns on this invention was demonstrated, you may provide a new process between each process, or before and behind in the range which does not have a bad influence on each process. For example, a coal pulverization step for pulverizing raw coal, a step for adjusting softening and melting properties by heat treatment, a removal step for removing unnecessary substances such as dust, a drying step for drying the obtained non-solvent extract, etc. Good.

  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. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

  The production method of the highly reactive coke according to the present invention will be specifically described with reference to examples.

<Manufacture of non-extracted coal>
A slurry was prepared using Coal-A (5 kg), which is a general coal as a raw material coal, and methylnaphthalene (20 kg) as a solvent. This slurry was pressurized with 1.2 MPa of nitrogen and heat-treated in an autoclave with an internal volume of 30 L (liter) at 370 ° C. for 1 hour (extraction process). Next, the slurry is transferred to a gravity sedimentation tank maintained at the same temperature and pressure, separated into a solvent-soluble component and a solvent-insoluble component (solid-liquid separation process), and after extracting the solvent-insoluble component from the lower part of the gravity sedimentation tank The solvent was separated and removed by distillation (solvent removal step) to obtain non-solvent extracted charcoal. Similarly, after extracting the solvent-soluble component from the upper part of the gravity settling tank, the solvent was separated and removed by distillation to obtain solvent-extracted charcoal.

<Properties of raw coal, non-solvent extracted coal, solvent extracted coal>
Components shown in Tables 1 and 2 were analyzed for raw coal (Coal-A), non-solvent extracted coal, and solvent extracted coal.

  Specifically, these ash concentrations were measured according to industrial analysis (JIS M8812). Further, regarding the metal element concentration, Na and K were incinerated at a temperature at which volatilization did not occur (700 ° C.), extracted with hydrochloric acid, and then quantified by an atomic absorption method. Si was incinerated at 815 ° C., dissolved with sodium carbonate or a mixture (sodium carbonate + sodium tetraborate), extracted with hydrochloric acid, and quantified by absorptiometry or ICP emission spectroscopic analysis depending on the concentration. Other metals (Al, Fe, Mg, Ca, Ti) were incinerated at 815 ° C., dissolved in the above mixture, extracted with hydrochloric acid, and quantified by atomic absorption or ICP emission spectroscopic analysis depending on the concentration. C, H, N, S, N, and Cl were measured by the method of JIS M8813. The moisture was measured by the method of JIS M8811. The calorific value was measured by the method of JIS M8814.

  These results are shown in Tables 1 and 2.

  From the results in Tables 1 and 2, the non-solvent extracted coal is rich in ash and contains many elements such as Fe and Ca, compared to raw coal (Coal-A) and solvent extracted coal. I found out.

  Moreover, it measured by the mercury method about the pore volume of raw material coal (Coal-A), non-solvent extraction coal, and solvent extraction coal. The results are shown in FIG.

  From FIG. 3, although the pore volume of raw material coal (Coal-A) and solvent extraction coal was substantially the same, the pore volume of non-solvent extraction coal compared with raw material coal (Coal-A) and solvent extraction coal. It was found that the pore volume was about twice.

<Manufacture of coke>
(Mixing process)
Various raw coals listed in Table 3 (strongly caking coal A, strong caking coal B, semi-caking coal C, and slightly caking coal D) and non-solvent extracted coal obtained as described above In the ratio shown in Table 4 below, the mixture was mixed well at room temperature, and adjusted to a packing density of 800 kg / m ³ and a moisture content of 7.8% to obtain a mixture (mixing step). The raw coal used was pulverized so that the particle size of 3 mm or less was 80% by mass or more. The non-solvent extracted coal used was pulverized so that the particle size of 1 mm or less was 100% by mass. Table 3 shows the results of examining the components of each raw coal and non-solvent extracted coal.

Volatile content (VM) was measured based on JIS M8812.
Ash content (Ash) was measured based on JIS M8812.
The reflectance (Ro) was measured based on JIS M8816.

  The softening and melting property (log MF) was measured by the Gieseler plastometer method defined in JIS M8801.

(Dry distillation process)
Coke was produced in a can baking test using a 300 kg scale test furnace. Specifically, the mixture obtained in the above step was heated from room temperature to 1050 ° C. at a rate of temperature increase of 3 ° C./min, and then kept in a furnace controlled at 1050 ° C. to 1060 ° C. for about 16 hours and dry-distilled. (Crying process), coke of Example 1 and Comparative Example 1 was produced.

<Characteristic evaluation of coke>
(Strength)
The strength of the coke obtained by dry distillation was measured with a drum index DI ¹⁵⁰ ₁₅ based on JIS K2151. As a result, both the coke of Example 1 and Comparative Example 1 exhibited a drum index (DI ¹⁵⁰ ₁₅ ) of 80 or more and had sufficient strength.

(Hot reactivity: CRI)
For the hot reactivity, the reaction was performed for 2 hours at 1100 ° C. in a carbon dioxide atmosphere, and the reaction rate was calculated from the change in weight after the reaction.

(Strength after reaction: CSR)
The strength after the reaction was evaluated based on the weight on a 9.5 mm sieve after applying an impact of 600 revolutions (20 revolutions per minute) to the sample after the hot reactivity test with a type I strength tester. Table 4 shows the test blend ratios and the results. Although the strength decreases after the reaction, this coke is a highly reactive coke, and there is no problem in use if the high strength coke is distinguished from the form of use.

  Example 1 is a coke for iron making obtained by a production method that satisfies the requirements of the present invention, in which non-solvent extracted coal was blended, and showed high hot reactivity (41.3). . On the other hand, although the comparative example 1 is the coke which mix | blended the slightly caking coal D instead of the non-solvent extraction charcoal, hot reactivity was inferior to Example 1. FIG. In addition, although the post-reaction strength of Example 1 is lower than that of Comparative Example 1, there is no problem in use if this coke is a highly reactive coke and the high-strength coke is distinguished from the form of use.

  In this example, the result of coke in which a part of slightly caking coal was replaced with non-solvent extracted coal was described, but if it is replaced with good quality coal (caking coal), further improvement in reactivity is expected. it can. It has been found that application of the present invention makes it possible to obtain highly reactive coke with an inexpensive raw material and is useful as a method for producing highly reactive coke.

Claims (4)

An extraction step of extracting a soluble component from coal with a solvent to obtain a mixture slurry of the solvent-soluble component and the solvent-insoluble component;
A solid-liquid separation step of separating the mixture slurry into a solvent-soluble component and a solvent-insoluble component using solid-liquid separation means;
Removing the solvent from the solvent-insoluble component to obtain a non-solvent extracted charcoal; and
A mixing step in which the non-solvent extracted coal and raw coal are mixed to form a mixture;
A carbonization step of carbonizing the mixture to obtain highly reactive coke;
A method for producing coke for iron making, comprising:   The method for producing coke for iron making according to claim 1, wherein the non-solvent extracted coal does not contain the solvent-soluble component obtained by the solid-liquid separation step.   The method for producing coke for iron making according to claim 1 or 2, wherein a mass ratio of the non-solvent extracted coal and the raw coal in the mixture is 1:99 to 30:70.   The method for producing coke for iron making according to any one of claims 1 to 3, wherein the raw coal is at least one selected from the group consisting of strongly caking coal, semi-caking coal, and slightly caking coal.

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