JP5466106B2 - Method for producing iron ore-containing coke - Google Patents

Description

  The present invention relates to a method for producing iron ore-containing coke (sometimes referred to as ferro-coke) by forming a mixture containing coal, iron ore and a binder and then subjecting it to dry distillation.

  Coke is usually produced by heat-drying raw coal at around 1000 ° C. This coke is inserted into the blast furnace so that the coke layer and the iron ore layer overlap each other, and hot air is blown from the tuyere to burn the coke, and the reducing gas generated at this time causes the coke to be contained in the iron ore. Pig iron can be produced by reducing iron oxide.

  In recent years, it has been studied to produce pig iron by blending iron ore-containing coke with iron ore in an iron ore layer. By adding iron ore-containing coke to the iron ore layer, reduction of iron oxide in the iron ore layer is promoted by reducing gas generated by burning the iron ore-containing coke, and iron in the iron ore-containing coke. It is considered that pig iron production efficiency is improved by the catalytic action of the components.

  The iron ore-containing coke can be produced by molding a mixture of coal, which is a raw material for coke, and iron ore, and subjecting the resulting molded body to dry distillation. However, the adhesion between coal and iron ore is weak, and there is a problem in that a molded body cannot be formed, or even if a molded body can be formed, the strength is low and the handleability is poor. Further, since iron ore-containing coke obtained by coking by forming a molded body is put into a blast furnace and used, strength that does not crush in the blast furnace is required.

  Therefore, Patent Document 1 proposes a technique for increasing the strength of a compact formed by molding a mixture of coal and iron ore and the strength of iron ore-containing coke obtained by dry distillation of the compact. In Patent Document 1, a raw material containing coal, an iron source material, and a binder is formed into a lump molded product, and the lump molded product is subjected to dry distillation to produce ferro-coke. A point binder and a low softening point binder having a softening point of less than 150 ° C. are used in combination. And this literature 1 can improve the intensity | strength of the lump molded object after shaping | molding by using the low softening point binder whose softening point is less than 150 degreeC, and uses the high softening point binder whose softening point is 150 degreeC or more. It is described that both the strength of the lump-molded product after molding and the strength of ferro-coke after dry distillation can be increased. Examples of the low softening point binder having a softening point of less than 150 ° C. include SOP (soft pitch), PDA (propane desulfurized asphalt), and medium pitch, and as a high softening point binder having a softening point of 150 ° C. or higher. As an example, ASP (asphalt pitch) is exemplified. The binders exemplified in this document 1 are all derived from crude oil.

  On the other hand, the present inventors have proposed in Patent Document 2 a method for producing an agglomerated composition for iron making by forming an agglomeration composition containing an iron oxide raw material and a carbonaceous material. In this document 2, a softening fluidity promoter is blended together with an iron oxide raw material and a carbonaceous material in order to produce an iron agglomerated carbonaceous material agglomerated product that has high strength and promotes a reduction reaction during ironmaking. As this softening fluidity promoter, coal extract (hypercoal) is used.

JP 2007-277489 A JP 2005-325435 A

  Patent Document 1 proposes a technique for increasing the strength of ferrocoke after dry distillation by using a high softening point binder having a softening point of 150 ° C. or higher. However, as a result of investigations by the present inventors, the strength of ferrocoke sometimes declines even when a high softening point binder is used. In addition, since a crude oil-derived binder such as asphalt pitch contains a large amount of sulfur (S) as an impurity (specifically, about 5% by mass or more), S remains in the ferrocoke after dry distillation, Ferro-coke quality was low. On the other hand, in the said patent document 2, although the coal extract is used as a softening fluidity | liquidity promoter, in this literature 2, it is not described about dry-distilling the carbonaceous material agglomerate for iron making, and it is not in dry distillation. No attention has been paid to improving the strength when subjected to a corresponding thermal history (for example, heating around 1000 ° C.).

  The present invention has been made in view of such circumstances, and an object thereof is to provide a method for producing high-quality iron ore-containing coke having high strength and low S content.

  The present inventors have repeatedly studied in order to provide a method capable of increasing the strength of iron ore-containing coke and improving the quality of iron ore-containing coke. As a result, the strength of the iron ore-containing coke is reduced because the binder to be blended to increase the adhesion between coal and iron ore when forming a compact expands during dry distillation, reducing the density of the iron ore-containing coke. I found out that there is something to do. Moreover, it became clear that in order to reduce the amount of S contained in iron ore-containing coke and improve the quality, it is sufficient to use a coal extract instead of a petroleum-derived compound as the binder.

  That is, the above-mentioned problem is a method of producing an iron ore-containing coke by dry distillation after molding a mixture containing coal, iron ore and a binder. This can be solved by using a coal extract having an expansion rate of 110 to 200%.

  According to the present invention, since the coal extract is used as a binder for enhancing the adhesion between coal and iron ore, the amount of S contained in the iron ore-containing coke can be reduced, and the quality of the iron ore-containing coke can be improved. . Further, in the present invention, among coal extracts, particularly those having an expansion rate of 110 to 200% are selected and used, so that the binder can be prevented from expanding during dry distillation, and the strength of iron ore-containing coke can be prevented. Can be increased.

  In the present invention, a mixture containing coal, iron ore, and a binder is molded and then carbonized to produce iron ore-containing coke. And the manufacturing method of this invention uses a coal extract whose expansion rate is 110-200% when heating to 500 degreeC and performing an expansibility test as a binder for improving the adhesiveness of coal and iron ore. There is a feature.

  First, the binder used in the present invention will be described. In this invention, the amount of S contained in iron ore containing coke can be reduced and quality can be improved by using a coal extract as a binder. As will be described later, the coal extract is obtained by subjecting a soluble component extracted from coal with a solvent to a modification treatment. This soluble component is a component consisting only of an organic substance obtained by removing inorganic substances from coal, and is generally called ashless coal (Hyper Coal; HPC). The amount of S contained in coal is less than the amount of S contained in petroleum, and the amount of S contained in coal is generally 1.5% by mass or less. Therefore, the amount of S contained in the soluble component can be reduced to approximately 1% by mass or less by using coal as a raw material for extracting the soluble component. Therefore, also about the coal extract obtained by carrying out the modification process of a soluble component, S content will be 1 mass% or less in general. As a result, S content can be reduced also about the iron ore containing coke which mix | blended this coal extract as a binder, and the quality of iron ore containing coke can be improved.

  In the present invention, it is important to use a coal extract obtained by modifying the soluble component as a binder, and the coal extract is expanded when heated to 500 ° C. and subjected to an expansibility test. By using the one having a rate of 110 to 200%, the strength of the iron ore-containing coke can be increased.

  That is, as disclosed in the above-mentioned Patent Document 1, when a mixture containing coal, iron ore and a binder is formed and then dry-distilled, as will be clarified in Examples described later, depending on the type of binder used, The strength of iron ore-containing coke sometimes decreased. When this cause was examined, it was found that the strength reduction of the iron ore-containing coke was caused by the density reduction, and this density reduction was caused by the expansion of the binder during dry distillation. The cause of this expansion is considered to be that the binder contains a compound having a low molecular weight and a low boiling point. Since a compound having a low molecular weight and a low boiling point volatilizes during dry distillation, it is considered that the density of the iron ore-containing coke as a whole is reduced by foaming the binder.

  Therefore, the present inventors examined the relationship between the expansion coefficient of the binder and the strength of coke containing iron ore after carbonization, and as a binder for improving the adhesion between coal and iron ore, a coal extract having an expansion coefficient of 200% or less. It has been clarified that the use of can prevent the binder from excessively expanding during the dry distillation and reduce the density of the iron ore-containing coke and can increase the strength. The expansion coefficient is preferably 180% or less, more preferably 160% or less. However, if the expansion coefficient is too small, the softening and melting property due to heating is low, so the coal extract hardly flows and penetrates between the coal and iron ore when dry distillation, increasing the adhesion between the coal and iron ore. I can't. Therefore, in the present invention, a coal extract having an expansion rate of 110% or more is used. Preferably it is 115% or more, More preferably, it is 120% or more.

  The expansion coefficient is the maximum expansion coefficient when the expansion coefficient of the coal extract at room temperature is 0% when the expansion test specified in JIS M8801 is performed and the coal extract is heated to 500 ° C. means. A dilatometer is used to measure the expansion coefficient.

  The test temperature of the expansibility test is from room temperature to 500 ° C. The softening / melting / expansion of the coal extract generally occurs in a temperature range of 500 ° C. or lower, and when the temperature exceeds 500 ° C., the coal extract is solidified, so that the expansion rate cannot be measured. Therefore, the behavior of the coal extract in the dry distillation temperature region (specifically around 1000 ° C.) is predicted by measurement up to 500 ° C.

  Since the softening meltability of coal extract is better than that of coal itself, when trying to measure the expansion rate by the method specified in JIS M8801, the coal extract is not between the cylinder and piston of the dilatometer. Leakage and expansion rate cannot be measured accurately. Therefore, in the present invention, coke breeze powder having almost no expansibility is used and mixed with the coke breeze powder so that the concentration of the coal extract is 20% by mass, 30% by mass or 50% by mass. The expansion rate is measured, and the expansion rate of the coal extract is estimated from the extrapolated value of each measured value.

  A coal extract having an expansion rate of 110 to 200% is obtained by extracting soluble components from coal with a solvent (extraction step), removing undissolved coal from the obtained extract (solid-liquid separation step), Can be produced by subjecting the soluble component contained in the product to a modification treatment (modification step).

<< Extraction process >>
In the extraction process, the soluble component extraction coal is brought into contact with the solvent to extract the soluble component from the coal.

  As a solvent used for extraction of a soluble component, 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.

  The solvent used for extraction of the soluble component preferably has a boiling point of 180 to 330 ° C (particularly 200 to 250 ° C). 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 extract separated in the solid-liquid separation step described later, or to remove the solvent adhering to the coal after extracting the soluble component, Solvent recovery is reduced.

  Although the kind of coal used for extraction of a soluble component is not specifically limited, It is preferable to use inferior quality coal. By using inexpensive coal, soluble components can be manufactured at low cost, so that economic efficiency can be improved. Of course, it is not limited to inferior quality coal, You may use high grade coal, such as bituminous coal.

  Inferior coal refers to coal such as non-thin coal having almost no softening and melting property, steam coal, low-grade coal, and the like. Low-grade coal is coal that normally contains 20% by weight or more of water and is desired to be dewatered. Examples of such low-grade coal include lignite, lignite, and sub-bituminous coal. Examples of the brown coal include Victoria coal, North Dagota coal, and Belga coal. Examples of the subbituminous coal include West Banco coal, Vinungan coal, and Samarangau coal. The low-grade coal is not limited to those exemplified above, and any coal containing a large amount of water and desired to be dehydrated is included in the low-grade coal referred to in the present invention.

  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 while stirring, a soluble component (hypercol) soluble in the solvent contained in coal is 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 process >>
In the solid-liquid separation step, soluble components are extracted from coal in the extraction step, and then undissolved coal (coal remaining after extraction of components soluble in the solvent) is separated to recover the liquid component. This liquid component is composed of a soluble component extracted from coal and a solvent used for extraction.

  The method for solid-liquid separation is not particularly limited, and a known method may be employed, and 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 gravity settling method, liquid content can be obtained from the upper part of the gravity settling tank, and undissolved coal can be obtained from the lower part. Therefore, it is preferable.

  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.

《Reforming process》
In the reforming step, the soluble component extracted from coal is subjected to a reforming treatment, and the expansion rate of the soluble component is adjusted to a range of 110 to 200%.

  In the reforming step, the extraction liquid (liquid component) obtained in the solid-liquid separation step may be subjected to a reforming process described later, or the solvent contained in the extract solution (liquid component) is removed ( You may perform the modification | reformation process mentioned later with respect to the concentration soluble component obtained by a solvent removal process.

  In the solvent removal step, the solvent is separated from the liquid obtained in the solid-liquid separation step. Thereby, a soluble component with little concentration of ash can be obtained. The ash content means residual inorganic substances (silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, etc.) when the soluble component is incinerated at 815 ° C. In the present invention, the content of ash contained in the soluble component is preferably 5000 ppm or less (more preferably 2000 ppm or less) 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.

  In the reforming step, in order to adjust the expansion coefficient of the soluble component to a range of 110 to 200%, the soluble component contained in the extract (liquid component) obtained in the solid-liquid separation step (a) A method of heating at a temperature higher than the extraction temperature and at 400 to 500 ° C., and (b) removing the solvent from the extracted liquid (liquid component) obtained in the solid-liquid separation step in an oxidizing atmosphere. And heating at 100 to 300 ° C.

  As in the method (a) above, by heating the soluble component contained in the liquid component to 400 to 500 ° C. (especially 420 to 480 ° C.), the easily gasifying component that causes expansion during dry distillation is previously obtained. Since it can be removed and the molecular weight of the soluble component can be increased, the boiling point can be increased. As a result, even when the temperature reaches the dry distillation temperature range, the gasification of the soluble component is small, and the expansion rate of the soluble component can be adjusted to a range of 110 to 200%.

  The heating temperature is set higher than the extraction temperature when a soluble component is extracted from coal in the extraction step. After bringing the solvent into contact with coal, heating to 400 to 500 ° C. at once will try to serve both extraction and reforming, so that the polymerization reaction occurs with the thermal decomposition of the coal, so the extraction rate of soluble components decreases. . Therefore, by combining the low temperature extraction and the high temperature reforming, the soluble component can be efficiently extracted, and the expansion coefficient of the soluble component can be adjusted in the range of 110 to 200%.

  The heating time may be set so that the expansion coefficient of the soluble component before the modification treatment and the expansion temperature of the soluble component after the modification treatment are in the range of 110 to 200% according to the heating temperature. .

  The soluble component may be obtained by heating the extract (liquid component) obtained in the solid-liquid separation step to 400 to 500 ° C., or removing the solvent from the extract solution (liquid component) obtained in the solid-liquid separation step. The concentrated soluble component may be recovered once removed, and the concentrated soluble component may be dissolved in another solvent and then heated to 400 to 500 ° C. As another solvent for dissolving the concentrated soluble component, those exemplified as the solvent used when extracting the soluble component from coal in the extraction step can be used. However, since a polar solvent or a hydrogen donating solvent (for example, N-methylpyrrolidone, tetrahydronaphthalene, etc.) changes in quality when heated to 400 ° C. or higher, it is preferable to use a hydrogen non-donating solvent. The solvent used in the extraction step and the solvent used in the modification step may be the same or different. In addition, when heating the said soluble component to 400-500 degreeC in a solvent, it is good to pressurize so that a solvent may not boil.

  On the other hand, even when the soluble component is heated at 100 to 300 ° C. (especially 130 to 270 ° C.) in an oxidizing atmosphere (for example, air) as in the method (b), the expansion coefficient is 110 to 200. % Can be adjusted. By heating in an oxidizing atmosphere, a cross-linked structure of a soluble component is developed by a dehydrogenation reaction or the like, and an expansion coefficient is in a range of 110 to 200%. However, when the heating temperature in the oxidizing atmosphere exceeds 300 ° C., the oxidation reaction becomes remarkable, and in some cases, the soluble component burns. Therefore, the expansion coefficient can be adjusted to a range of 110 to 200%. Can not. In addition, although the said soluble component can adjust an expansion coefficient to the range of 110-200% even if it heats to about 400-500 degreeC in non-oxidizing atmosphere (for example, nitrogen), it heats to this temperature range. In this case, it is convenient to perform the modification treatment in a solvent as an extension of the extraction step as in the method (a).

  The heating time may be set so that the expansion coefficient of the soluble component before the modification treatment and the expansion temperature of the soluble component after the modification treatment are in the range of 110 to 200% according to the heating temperature. .

  The coal extract obtained by adjusting the expansion rate in the range of 110 to 200% as described above is used as a binder for coal and iron ore. The binder is made into a mixture with coal and iron ore (mixing step), then formed (molding step) and dry-distilled (dry distillation step) to become iron ore-containing coke. In the following, description will be given in order.

《Mixing process》
In the mixing step, coal, iron ore, and coal extract are mixed. This is to obtain a uniform mixture.

  The mixing method of coal, iron ore, and coal extract is not particularly limited. In addition to the method of simultaneously mixing coal, iron ore, and coal extract, the coal extract is mixed with coal and iron ore. The method of adding and mixing, the method of adding and mixing iron ore to the mixture of coal and coal extract, the method of adding and mixing coal to the mixture of iron ore and coal extract, etc. It is done.

  The means for mixing coal, iron ore, and coal extract is not particularly limited, and for example, a mixer, a kneader, a single screw mixer, a twin screw mixer, or the like can be used.

(coal)
As coal, the coal illustrated as coal used for the extraction of the said soluble component can be used.

  As for the particle size of coal, it is preferable that 70 mass% or more (more preferably 80 mass% or more, more preferably 90 mass% or more) is 3 mm or less. If the coal having a particle size exceeding 3 mm exceeds 30% by mass, the strength of the obtained iron ore-containing coke may be lowered.

(Iron ore)
The type of iron ore is not particularly limited, and hematite (hematite; Fe ₂ O ₃ ), magnetite (magnetite; Fe ₃ O ₄ ), limonite (Fe ₂ O ₃ .nH ₂ O), etc. are generally mixed Available iron ore can be used. Furthermore, iron oxyhydroxide (FeOOH) can be used as a raw material.

  When the particle size of coal is in the above range, the iron ore particle size is preferably 200 μm or less (more preferably 170 μm or less, and still more preferably 150 μm or less). If the particle size of the iron ore is too large, the stress acting on the interface of the iron ore becomes large, so that the strength of the obtained iron ore-containing coke may be reduced. In addition, the lower limit of the particle size of the iron ore is not particularly limited, and the smaller the better, but for example, it is preferably 30 μm (more preferably 50 μm, still more preferably 70 μm). This is because it takes time and effort to obtain an iron ore having a particle size of less than 30 μm, and the manufacturing cost increases.

(Coal extract)
The particle size of the coal extract is preferably 10 mm or less (more preferably 5 mm or less), more preferably 0.1 mm or more (more preferably 0.5 mm or more) when the coal particle size is in the above range. Is preferred.

  The “particle size” is a value obtained by a sieving method.

(Mixing amount)
The amount of iron ore is preferably 10 parts by mass or more (more preferably 20 parts by mass or more), and preferably 50 parts by mass or less (more preferably 45 parts by mass or less) with respect to 100 parts by mass of coal.

  The mixing ratio of coal and iron ore (coal / iron ore) is preferably, for example, 90/10 to 60/40 (particularly 80/20 to 70/30) on a mass basis.

  The blending amount of the coal extract is preferably 5 parts by mass or more (more preferably 7 parts by mass or more) and 20 parts by mass or less (more preferably 15 parts by mass or less) when the total of coal and iron ore is 100 parts by mass. ) Is preferred.

  In the present invention, as long as the adhesion between coal and iron ore is not impaired, a coal extract having an expansion rate exceeding 200% may be slightly blended.

  The amount of the coal extract whose expansion coefficient exceeds 200% is acceptable up to about 5 parts by mass (more preferably about 3 parts by mass) when the total amount of coal and iron ore is 100 parts by mass.

<Molding process>
In the molding step, the mixture is molded into a molded product having a predetermined strength. When the iron ore-containing coke of the present invention is produced by dry distillation using, for example, a vertical shaft furnace, the molded product is introduced from the top of the shaft furnace, so that it is difficult to separate coal and iron ore (predetermined It is required to have the following strength.

  The method for molding the mixture is not particularly limited. For example, in addition to a method using a double roll (double roll) molding machine using a flat roll, a double roll molding machine having an almond 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 molding of the mixture may be cold molding performed at around room temperature or hot molding 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.

《Dry distillation process》
In the dry distillation step, iron ore-containing coke can be produced by dry distillation of the molded body obtained in the molding step. 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.

  Known conditions can be adopted as the carbonization conditions, the carbonization temperature is about 650 to 1100 ° C. (especially about 700 to 1050 ° C.), and the carbonization time is about 5 minutes to 24 hours (particularly about 10 minutes to 12 hours). do it. The dry distillation atmosphere may be a non-oxidizing gas atmosphere in order to prevent deterioration due to oxidation of coal.

  In the iron ore-containing coke obtained in this way, since the binder hardly expands during dry distillation, the decrease in density is suppressed and the strength is high. Moreover, since the coal extract is used as the binder, the iron ore-containing coke contains almost no S and the quality is high. Therefore, even if this iron ore-containing coke is charged into a blast furnace to produce pig iron, the iron ore-containing coke can be crushed in the blast furnace or the quality of the pig iron can be prevented from being degraded.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the following examples are not intended to limit the present invention, and may be implemented with appropriate modifications within a range that can meet the purpose described above and below. These are all possible and are within the scope of the present invention.

  A mixture containing coal, iron ore and a binder was formed and then carbonized to produce iron ore-containing coke.

"coal"
Coal was adjusted so that the ratio of particles having a particle size of 3 mm or less was 90% by mass or more by using general coal having the component composition shown in Table 1 below. The amount of ash is shown based on the mass when the coal is dried (db), and was measured according to JIS M8812. In addition, d. a. f. (Dry ash free) means the content (mass%) of the organic substance (C, H, N, S, O) obtained by removing moisture and ash from coal, and is measured according to JIS M8819.

"Iron ore"
The iron ore having the component composition shown in Table 2 below was used and pulverized to adjust the diameter to 100 μm or less.

"binder"
Coal extracts a to e prepared by the following procedure were prepared and pulverized so as to have a diameter of 1 mm or less as a binder.

(Coal extract a)
Heat charcoal having the composition shown in Table 1 below was heated and stirred in methyl naphthalene to extract soluble components contained in the heat charcoal. The general charcoal used what was grind | pulverized so that a diameter might be 3 mm or less. Extraction of the soluble component was performed in a nitrogen atmosphere, the extraction temperature was 380 ° C., and the extraction time was 60 minutes. In addition, extraction was performed by pressurizing so that methylnaphthalene would not boil.

  After extracting soluble components from steam coal, the extract was separated into solid and liquid by gravity sedimentation, and separated into steam charcoal undissolved in methylnaphthalene and other liquid components. Methylnaphthalene was removed from the separated liquid and the soluble component was recovered. This soluble component was designated as coal extract a.

(Coal extract b)
The coal extract a is pulverized to a diameter of 1 mm or less, then heated in anthracene oil at 450 ° C. for 30 minutes for reforming treatment, and then the anthracene oil is removed to dissolve the component. The soluble component was designated as coal extract b. The reforming treatment was performed under pressure so that the anthracene oil did not boil. The anthracene oil was removed by heating under reduced pressure.

(Coal extract c)
The coal extract a is pulverized so as to have a diameter of 1 mm or less, heated in anthracene oil at 510 ° C. for 30 minutes for reforming treatment, and then the anthracene oil is removed to remove soluble components. This soluble component was designated as coal extract c. The reforming treatment was performed under pressure so that the anthracene oil did not boil. The anthracene oil was removed by heating under reduced pressure.

(Coal extract d)
The coal extract a was pulverized so as to have a diameter of 1 mm or less, and then subjected to reforming treatment by heating at 180 ° C. for 10 minutes in the air, to be a coal extract d.

(Coal extract e)
The coal extract a was pulverized so as to have a diameter of 1 mm or less, and then subjected to a reforming treatment by heating at 320 ° C. for 10 minutes in air to obtain a coal extract e.

  The coal extracts a to e thus obtained were pulverized so as to have a diameter of 1 mm or less, and then the expansion coefficient was measured.

  The expansion coefficient was measured by conducting an expansibility test (dilatometer method) defined in JIS M8801. A dilatometer was used to measure the expansion coefficient, and the maximum value of the expansion coefficient when heated from room temperature to 500 ° C. was measured. In this example, when measuring the expansion coefficient of the coal extract, a coke breeze powder having almost no expansibility is used, and the concentration of the coal extract is 20% by mass, 30% by mass, and 50% by mass. The coke breeze powder was mixed so that the expansion coefficient of this mixture was measured, and the expansion coefficient of the coal extract was estimated from the extrapolated value of each measurement value. The expansion rates of the coal extracts a to e are shown in Table 3 below.

<< Mixing process, molding process >>
Coal, iron ore, and coal extract are mixed at the ratio shown in Table 3 below at room temperature, and the mixture is pressure-formed while being heated to 300 ° C using a double roll molding machine having an almond-type pocket with a capacity of 5 ml. Thus, a molded body was formed.

《Dry distillation process》
The obtained molded body was heated from room temperature to 850 ° C. at a temperature rising rate of 3 ° C./min in a nitrogen atmosphere, and then kept at this temperature for 10 minutes to dry distillation to produce iron ore-containing coke.

(Strength)
The strength of iron ore-containing coke obtained by dry distillation was evaluated by a crushing load according to ISO 4700. Specifically, when a load was applied to the central portion of the molding surface that was in contact with the double roll, the load when the iron ore-containing coke was crushed was measured. The measurement results are shown in Table 3 below.

(S content)
Moreover, as a result of measuring S content contained in the iron ore containing coke obtained by dry distillation according to JISM8819, S content was 0.3 mass% or less also in any coke.

  From Table 3 below, it can be considered as follows. No. 2 and No. 4 is an example satisfying the requirements defined in the present invention, and a coal extract having an expansion coefficient in the range of 110 to 200% when heated to 500 ° C. as a binder and subjected to an expansion test is used. For this reason, the binder expands appropriately during the carbonization, and the strength of the iron ore-containing coke obtained by the carbonization is increased.

  On the other hand, no. 1, 3, and 5 are examples that do not satisfy the requirements defined in the present invention. In particular, no. No. 1, since the expansion rate of the coal extract used as the binder exceeds 200%, it is estimated that the binder significantly expanded during the dry distillation, and the density of the iron ore-containing coke obtained by the dry distillation is reduced, The strength was lowered.

  No. 3 and no. No. 5, because the expansion rate of the coal extract used as the binder is less than 110%, it is estimated that the binder hardly expanded during the dry distillation, and the adhesion between the coal and iron ore could not be improved. The strength of iron ore-containing coke obtained by carbonization was lowered.

  No. 6 is an example in which a mixture of coal and iron ore was formed and dry-distilled without using a binder. As a result, the compact collapsed during carbonization, and iron ore-containing coke could not be produced.

Claims (3)

A method for producing iron ore-containing coke by dry distillation after molding a mixture containing coal, iron ore and a binder,
The method for producing iron ore-containing coke, wherein the binder is a coal extract and has an expansion rate of 110 to 200% when an expansion test is performed by heating to 500 ° C.   As the coal extract, a soluble component is extracted from coal with a solvent, and after removing undissolved coal from the obtained extract, the soluble component contained in the liquid is higher than the extraction temperature and is 400 to 500 ° C. The manufacturing method according to claim 1, wherein a product that has been heated and reformed is used.   As the coal extract, a soluble component is extracted from coal with a solvent, undissolved coal is removed from the obtained extract, and then the concentrated soluble component obtained by removing the solvent from the liquid is oxidized in an oxidizing atmosphere. The manufacturing method of Claim 1 using what was heated and modified at -300 degreeC.