KR20170048512A - Method for deciding blending amount of ash-free coal, and process for producing coke for blast furnace - Google Patents

Abstract

An object of the present invention is to provide an efficient method for determining the blending amount of ashless coal in the production of blast furnace coke and a method for producing blast furnace coke using the same. The present invention relates to a method for determining the amount of ashless coal in the production of a blast furnace coke containing an ashless coal and a raw coal obtained by a solvent extraction treatment of coal, wherein the porosity index Pv [vol%] of the raw coal, the swelling The amount of the ashless coal in the compounded coal is determined by the reference value W [mass%] calculated by the following equation (1) using the index D [volume%] and the true specific gravity? Of the ashless coal. The amount of the above-mentioned ashless coal to be blended is preferably 0.29 W [mass%] or more and 1.00 W [mass%] or less.
&Quot; (1) "

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining blending amount of ashless coal and a method for producing blast furnace coke,

The present invention relates to a method for determining the amount of ashless coal and a method for producing coke for blast furnaces.

The coke used in steel making in the blast furnace is largely of a function as a filler for securing the air permeability in the furnace by enduring the function of the iron ore (iron oxide) as a reducing material, the function as a heat source (fuel), and the load of the coke itself and iron ore. Branch functions are expected. In order to perform these functions, the coke is required to have a certain strength and reactivity (reducing and combustibility).

Generally, coke is produced by burning coal at a high temperature of 1000 ° C or higher (hereinafter sometimes referred to as "dry running"). In the case of obtaining a coke having high strength, a so-called coarse coal having a high degree of cohesion is used, but such coarse carbon is relatively expensive. Therefore, for the purpose of reducing the production cost of coke, in addition to weak coking coal having lower degree of cohesiveness than cohesive coal, uncooked coal having insufficient cohesion property or noncondensable coal having almost no cohesion (hereinafter, uncooked coal and non- ) Is also blended in a certain amount as a coke raw material. The mechanism by which high-strength coke is produced has been found to a considerable extent, and various methods for efficiently obtaining high-strength coke have been proposed (see, for example, International Publication WO 2010/103828).

Here, the change of the coal particles in the carbonization process will be described. 1A is a view schematically showing this change, and the left side shows a state in which coal particles (coarse fine carbon particles 1 and non-fine cemented carbide particles 2) before being dried are present in roughening 10, Shows a state in which the continuous phase 1a formed by expanding the tough coal particle 1 and the altered component 2a of the non-fine cemented carbide particle 2 exist. The coarse-carbon particles 1 are melted in the course of the carbonization process, expanded by containing the generated gas, and joined with the adjacent coarse-grained particles 1 to form a continuous phase 1a containing the bubble A. When the proportion of the coarse carbon particles is more than a predetermined value and the ratio of the non-cemented cement can be small, the non-cemented cemented carbide particles 2 are inserted into the coarse carbon in the continuous phase forming process. However, when the ratio of the non-cemented carbide is high as shown in Fig. 1A, adhesion of the toughness carbon particles 1 is inhibited, and a coke having a coarse defect (B) therein is generated.

On the other hand, as a countermeasure for increasing the strength of the coke, there is known a method of using an ashless coal obtained by a solvent extraction treatment of coal as a cohesive filler (see, for example, JP-A-2014-43583). In this method, as shown in Fig. 1B, the strength of the coke is improved by dispersing and blending the ash-free particles 4 in the raw coal particles (coarse carbon particles 1 and non-fine cemented carbide particles 2). Specifically, the ashless particles 4 in the coke oven begin to flow at a temperature lower than that of the raw coal particles, and the continuous phase 4a (4a) derived from the ashless particle 4, including the center portion of the coke, ) Are formed approximately uniformly. Thereby, the continuous phase (1a) derived from the coarse carbon particles (1) and the denatured component (2a) of the non-coated cemented carbide particles (2) are connected to fill the voids between the particles. In addition, since the unshaped coal has higher expansion than the coarse coal, the unburnt particles 4 are expanded, so that the coal particles are connected to fill the voids between the particles, and high-strength coke can be produced.

However, since the characteristics of the ashless coal depend on the type of coal used as the raw material and the production conditions of the ashless coal, the preferred blending amount of the ashless coal is determined by carrying out a small-scale carbonization test and repeating trial and error. For this reason, it takes time to determine the preferable blending amount of the ashless coal, and the efficiency thereof has been demanded.

International Publication No. 2010/103828 Japanese Patent Application Laid-Open No. 2014-43583

The present invention has been made based on the above-described circumstances, and an object of the present invention is to provide an efficient method for determining the amount of ashless coal during blast furnace coke production and a method for producing blast furnace coke using the same.

As a result of intensive studies, the inventors of the present invention have found out that a suitable amount of ashless coal in blast furnace coke production can be determined by the porosity of the raw coal, the swellability of the ashless coal and the true specific gravity of the ashless coal, .

That is, the invention made to solve the above problems is a method for determining the ashless amount of blast furnace during the production of the blast furnace coke containing the ashless coal and the raw coal obtained by the solvent extraction treatment of coal, and the porosity index Pv [ Mass%] calculated by the following formula (1) using the specific gravity of the ashless carbon and the intrinsic specific gravity of the ashless carbon (% by volume), the swelling index D [vol%] of the ashless carbon, Is determined based on the amount of the component.

The method for determining the amount of ash tundish can calculate a preferable blending amount of ashless tundish at the time of producing the blast furnace coke by previously measuring the porosity of the raw coal, the swellability of the ash tundish and the true specific gravity of the ash tundish. Therefore, in the method for determining the amount of the ashless coal, the amount of ashless coal to be compounded can be efficiently determined without repeating trial and error by the test of carbonation. As a result, high-strength coke can be easily and reliably produced by using the method of determining the amount of ashless coal.

The amount of the above-mentioned ashless coal to be blended is preferably 0.29 W [mass%] or more and 1.00 W [mass%] or less. By setting the blending amount of the ashless coal to the compounded coal within the above-described range, it is possible to fill voids between the coal particles without waste and reliably by ashless coal.

The present invention is a method for producing a coke for blast furnace, comprising a step of blending the ashless coal obtained by the solvent extraction treatment of coal with the raw coal, and the step of dry-blending the blended coal, wherein in the blending step, And determining a blending amount of the ashless coal with respect to the compounding coal by using a crystallization method. The method for producing the blast furnace coke efficiently determines the blending amount of the ashless coal by using the method of determining the blend amount of the ashless coal, so that the high-strength coke can be easily and reliably produced while reducing the production cost.

The true specific gravity? Of the ashless carbon is a value measured in accordance with JIS-Z8807: 2012. The porosity index Pv (vol%) is a value obtained by dividing the mass density of the raw coal in the coke oven by d [kg / m 3] and the true specific gravity of the raw coal by ρc. Is a value calculated by Equation (2). The true specific gravity rho of the ashless coal is slightly different depending on the kind of the raw coal (that is, the coal for obtaining the ash-free coal) and the manufacturing conditions, and the true specific gravity rho c of the raw coal is slightly different depending on the coal tar. , The true specific gravity ρ of the ashless coal and the true specific gravity ρc of the raw coal can be set to 1.3 (see Fuel Analysis Test Method, Nankodo, p.130).

The " expansion index D [vol%] of the ashless coal " is a value measured by the following method. First, 1.8 g of anthracite pulverized to a particle diameter of 2 mm or less and 0.2 g of crushed unbaked carbon having a particle size of 200 탆 or less were filled in a quartz test tube having an inner diameter of 15 mm and heated to 500 캜 at 3 캜 / min. The expansion rate V 10% [volume%] is obtained from the ratio of the height of the sample after heating. Next, 1.6 g of anthracite crushed into a quartz test tube having an inner diameter of 15 mm and having a particle diameter of 2 mm or less and 0.4 g of an unburned carbon crushed to a particle diameter of 200 탆 or less were filled and heated to 500 캜 at 3 캜 / The expansion rate V20% [volume%] is obtained from the ratio of the height of the sample after heating to the height of the sample before. The intumescent index D [volume%] of the ashless carbon is obtained by the following equation (3).

The reason for not measuring the swelling index D of the ashless coal in accordance with the swelling test method of JIS-M8801: 2004 is that since the flowability of the ashless coal in the molten state is remarkably higher than that of ordinary coal, This is because measurements can not be applied. The reason for using anthracite coal in the above measurement method is as follows. Anthracite coal is one of the most abundant types of coal among coal, and is often used as a part of raw coal for the production of steel coke, but it has no integrity or fluidity. That is, since anthracite coal is not melted or expanded in the process of carbonization, the rate of expansion in the process of mixing the ash carbon with the coal particles and carrying out the carbonization is higher in accuracy We can expect to see it.

INDUSTRIAL APPLICABILITY As described above, the method for determining the amount of ashless coal in the present invention can efficiently determine the blending amount of the unburned coal at the time of manufacturing the blast furnace coke, so that the production method of the blast furnace blending method using this method High-strength coke can be easily and reliably produced while reducing the amount of coke.

FIG. 1A is a schematic view for explaining a state before and after carbonization of a coal in a conventional coke making method, and is a case where an ash is not used.
Fig. 1B is a schematic view for explaining a state before and after coal flowing in a conventional coke making method, and it is a case where ash is used.

Hereinafter, an embodiment of a method for producing a coke for a blast furnace using the method for determining the amount of ashless coal according to the present invention will be described.

The method for producing the blast furnace coke includes a step (blending step) of blending the ashless coal obtained by the solvent extraction treatment of coal with the raw coal, and a step (carburizing step) in which the blended carbon is distilled.

<Formulation process>

In the blending process, the ash coal is blended in the raw coal which is the raw material of the coke, and the blended coal is obtained.

(Raw coal)

The raw coal to be used as the raw material of the coke in the method for producing coke for blast furnaces is not particularly limited, and the raw coal of the coke is blended in a suitable ratio at which coarse coal can be fused by coagulation of tough coal, semi-tough coal, weak coking coal, Can be used in combination. Particularly, the raw coal preferably includes coarse coal and non-coking coal.

The lower limit of the ratio of tough coal in the raw coal is preferably 20% by mass, more preferably 30% by mass. The upper limit of the ratio of the coarse coal in the raw coal is preferably 50% by mass and more preferably 40% by mass from the viewpoint of producing a high-quality coke at lower cost. If the ratio of tough coal is less than the lower limit described above, the strength of the obtained coke may be insufficient. On the other hand, when the ratio of the tin coals exceeds the upper limit, there is a fear that the production cost of the coke increases.

It is preferable that the raw coal is finely ground. When the raw material coal is in the form of particles, the average particle diameter D20 of the raw coal is preferably 3 mm or less. When the average particle diameter D20 exceeds the upper limit, there is a fear that the compatibility with the ashless coal and the strength of the obtained coke become insufficient. The term &quot; average particle diameter D20 &quot; means that when the whole particles are sieved in order from a sieve having large eyes in a metal mesh specified in JIS-Z8801-1: 2006, the cumulative volume of the particles remaining on the sieve becomes the volume Of the sieve is 20% of the size of the sieve.

The raw coal may be dry coal by air drying or the like, but may be used in a state containing water.

(Unshi Tan)

Uncooked coal (HPC) is a kind of coal-reformed coal, which is a modified coal obtained by removing ash and inferiority components from coal as much as possible using a solvent. However, the ashless coal may include ash so far as it does not significantly impair the fluidity or expandability of the ashless coal. Generally, coal contains 7% by mass or more and 20% by mass or less of ash. In the ashless coal used in the method for producing the coke for blast furnace, the amount of ash may be about 2%, and in some cases about 5%. The term "ash" means a value measured in accordance with JIS-M8812: 2004.

Such ashless coal can be obtained by a solvent extraction treatment in which coal is mixed with a solvent having high affinity for the coal, an extract solution in which an insoluble component is separated from a solvent such as ash, and the solvent is removed from the extract. As a specific method of the solvent extraction treatment, for example, the method disclosed in Japanese Patent No. 4045229 can be used. The ashless coal obtained in such a solvent extraction treatment contains substantially no ash, is soluble in a solvent, contains a large amount of organic matter exhibiting softening and melting property, and structurally, from a relatively low molecular weight component having a condensed aromatic ring as a 2 or 3 ring, And has a broad molecular weight distribution up to a high molecular weight component having an aromatic ring of about 5 or 6 rings. Therefore, the ashless coal exhibits high fluidity under heating, and is generally melted at 150 ° C or more and 300 ° C or less regardless of the quality of the coal as the raw material. In addition, the ash tuyerase expands while generating a large amount of volatile components in an initial stage of the distillation of about 300 ° C to 500 ° C. Since the ash-free coal is obtained through dehydration of a mixture of coal and a solvent (slurry), the water content is about 0.2 mass% or more and about 3 mass% or less and has a sufficient calorific value.

The quality of the coal to be used as the raw material for the ashless coal used in the method for producing the blast furnace coke is not particularly specified. It is also preferable that the ashless coal has a small grain size in view of increasing the dispersibility and increasing the strength of the coke. The upper limit of the maximum diameter of the non-burnt particles is preferably 1 mm. When the maximum diameter of the ash-free particles exceeds the above-mentioned upper limit, the coupling effect of the above-mentioned coal particles can not be sufficiently obtained, and the strength of the coke may be insufficient. The maximum diameter of the ashless particles means the maximum length (the maximum distance between two points) of the outer shape of the ashless particles photographed by, for example, an electron microscope.

(Blending amount of ash)

The blend amount of the ash coal with respect to the blend coal (the sum of the raw coal and the unburned coal) is determined by the porosity index Pv [vol%] of the raw coal, the swelling index D [vol%] of the ashless coal and the true specific gravity ρ Is determined by the reference value W [mass%] calculated by the following equation (1).

&Quot; (1) &quot;

Here, it is considered that the porosity index Pv of the raw coal, the exponential index D of the ashless coal, and the true specific gravity? Of the ashless coal are all determined depending on the kinds of the raw coal and the ash coal and the conditions of the carbonization, Do. Therefore, the reference value W used in the determination method of the amount of the ash tundane can be calculated without repeating the trial and error by the carbon test.

The lower limit of the blending amount of the above-mentioned ashless coal to the compounded carbon is preferably 0.29 W [mass%], more preferably 0.31 W [mass%] and still more preferably 0.45 W [mass%]. The upper limit of the blend amount of the above-mentioned ashless coal to the compounded coal is preferably 1.00 W [mass%], more preferably 0.80 W [mass%]. In the later-described carbonization process, the ashless coal contains gas and expands, and is crashed together with an increase in temperature and progress of the carbonization, thereby forming an adhesive layer between the coal particles. If the amount of the above-mentioned ashless coal to be blended is less than the above-described lower limit, filling of the voids between the coal particles by the ash-free charging may be insufficient, and sufficient adhesion may not be obtained. On the other hand, when the blend amount of the above-mentioned ashless coal to the compounded carbon exceeds the upper limit, the adhesive layer is thickened, and the ashless coal which does not contribute to filling of the void increases, and the production cost of the coke is likely to increase. In addition, since the excessively expanded unburnt carbon becomes defective, the strength of the coke may be lowered. When the porosity index Pv of the raw coal used for calculating the reference value W, the exponential index D of the ashless coal, and the true specific gravity p of the ashless coal can include a measurement error, by making the blending amount of the ashless coal fall within the above range, The pores between coal can be filled with or without ash and the strength of the coke can be increased.

Here, the reference value W [mass%] is used to determine the amount of ashless coal to be blended to the blend. First, a value Pv / D x 100 [vol%] obtained by dividing the porosity index Pv [vol%] of the raw coal by the exponential index D [vol%] of the unburnt coal at the reference value W It is considered that this represents the volume of the unnecessary ash burnt. Since the ash-free particles have high fluidity when heated, and the pores of the raw coal can be substantially uniformly buried, by adding the amount of ashless coal necessary for embedding the pores of the raw coal to the raw coal, It is considered that the pores of the non-contact type can be efficiently filled with the ash. Therefore, multiplying this Pv / D x 100 by the true specific gravity rho of the ashless coal can be used as a reference value for determining the blending amount [mass%] of the ashless coal.

(Blend)

The lower limit of the logarithm (logMF) of the maximum flowability of the blend containing ashless coal in the raw coal is preferably 1.8, more preferably 2, and further preferably 2.1. On the other hand, the upper limit of logMF of the blend is preferably 3, more preferably 2.5, and still more preferably 2.3. When the logMF of the blended carbon is lower than the lower limit described above, the flowability of the blended carbon is insufficient, and the strength of the resulting coke may be insufficient. On the contrary, when the logMF of the blend exceeds the upper limit, the degree of fluidity becomes excessive, and bubbles may easily be generated in the coke. Also, the maximum flow MF indicates the magnitude of thermal fluidity, and the logMF of the compounded coal means the weighted average of the logMF of the total coal and the unburned coal contained in the raw coal.

The lower limit of the average maximum reflectance Ro of the blend is preferably 0.95, more preferably 1. [ On the other hand, the upper limit of the average maximum reflectance Ro of the compounded carbon is preferably 1.3, more preferably 1.2. When the average maximum reflectance Ro of the blended carbons is less than the lower limit described above, expansion or fusion of the raw coal or the non-coal tends to be insufficient due to the low coalification degree of the blend, which may result in insufficient strength of the obtained coke. On the contrary, when the average maximum reflectance Ro of the blend exceeds the upper limit, the expansion rate becomes too high, which may affect the roving body. In addition, the average maximum reflectance Ro mainly indicates the degree of coalification, and Ro of the compounded coal means a weighted average of Ro of all coal and non-coal included in the raw coal.

The method of mixing the ashless coal with the raw coal is not particularly limited, and for example, a method in which raw coal and unburned coal are introduced into a known mixer through a hopper, and the mixture is pulverized by a conventional method. By using this method, it is possible to pulverize secondary aggregated coarse particles and pulverize the raw coal into particles. Further, the pre-milled raw coal and non-coal may be mixed.

In addition, since the coal particles are connected by the ashless coal as described above in the production method of the coke, it is not necessary to add a binder to the raw coal. Therefore, from the viewpoint of cost reduction, it is preferable that the blended carbon does not contain the point settlement other than the non-coated carbon.

<Carrying process>

In the carbonization process, the compounded carbon is charged into a coke furnace and dried to obtain a coke. As this coke furnace, for example, a furnace having a furnace capable of charging about 30 tons per furnace can be used.

The lower limit of the filled bulk density d at the time of charging the blend coke into the coke oven is preferably 720 kg / m 3, more preferably 730 kg / m 3. The upper limit of the filled bulk density d is preferably 850 kg / m 3, more preferably 800 kg / m 3. When the filled bulk density d is less than the above lower limit, there is a fear that the strength of the coke becomes insufficient. On the other hand, when the filled bulk density d exceeds the upper limit, there is a fear that the pressure applied to the rotoce becomes high, thereby damaging the roto body, and an operation of improving the filling density of the blended carbon, thereby increasing the manufacturing cost of the coke .

The lower limit of the dry-running temperature of the blast furnace is preferably 950 ° C, more preferably 1000 ° C. Further, the upper limit of the gasification temperature is preferably 1200 ° C, and more preferably 1050 ° C. When the dry-running temperature is lower than the lower limit described above, there is a fear that the melting of the coal becomes insufficient and the strength of the coke is lowered. On the other hand, when the gasification temperature exceeds the upper limit, there is a fear that the production cost increases from the viewpoint of the heat resistance of the rosette and the fuel consumption.

The lower limit of the dry time of the compounding coal is preferably 8 hours, more preferably 10 hours. The upper limit of the duration of the dry period is preferably 24 hours, more preferably 20 hours. When the dry time is less than the lower limit described above, the coal is insufficiently melted and the strength of the coke is lowered. On the other hand, when the carbonization time exceeds the upper limit, the production cost may increase from the viewpoint of fuel consumption.

<Advantages>

The method for determining the amount of ash tundish can calculate a preferable blending amount of ashless tundish at the time of producing the blast furnace coke by previously measuring the porosity of the raw coal, the swellability of the ash tundish and the true specific gravity of the ash tundish. Therefore, in the method for determining the amount of the ashless coal, the amount of ashless coal to be compounded can be efficiently determined without repeating trial and error by the test of carbonation. As a result, high-strength coke can be easily and reliably produced by using the method of determining the amount of ashless coal.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

An ashless carbon was produced by the following method using a hypercoke continuous manufacturing facility (Bench Scale Unit). First, 5 kg of coal (that is, coal for obtaining an ash coal) and 4-fold amount of coal as a solvent (dry coal conversion mass) were used as the raw coal of the unburned coal (that is, coal for obtaining the unburned coal) (20 kg) of 1-methylnaphthalene (manufactured by Shinnitetsu Sumikin Kagaku Co., Ltd.) were mixed to prepare a slurry. This slurry was placed in a 30 L internal volume autoclave, pressurized with nitrogen at 1.2 MPa, and heated at 370 캜 for 1 hour. The slurry was separated into a supernatant and a solid concentrate in a gravity sedimentation medium maintained at the above-mentioned temperature and pressure, and the solvent was separated and recovered from the supernatant by a distillation method to obtain 2.7 kg of an unburned X. The ash and the swelling index D of the obtained ashless tan X were as shown in Table 1. [ This non-stratified X was pulverized so that the whole (100 mass%) had a maximum diameter of 3 mm or less.

3.2 kg of ash tantalum Y was obtained in the same manner as in the above-obtained method of obtaining the unsanitary X except that the gravity settling time was changed. Further, 4.5 kg of ashless Z was obtained in the same manner as in the above-mentioned method of obtaining the ashless X except that the gravity settling time was different from the gravitational settling time when the untreated X and the unshown Y were obtained. The obtained ashless aggregates Y and Z ash and the expandability index D were as shown in Table 1. The ash tuyeres Y and Z were pulverized so that the whole (100 mass%) had a maximum diameter of 3 mm or less.

&Lt; Examples 1 to 5 &

The coke for blasting according to Examples 1 to 5 was prepared by using the ashless X in the ashless coal produced as described above by the following procedure.

(Mixing process)

Various raw materials coal A to E having the characteristics shown in Table 2 as raw coal were respectively adjusted to moisture of 7.5% by mass and mixed in a mixing ratio condition 1 shown in Table 2 on a dry coal basis. At this time, the raw coal was pulverized so that the whole (100% by mass) of the raw coal had a maximum diameter of 3 mm or less. The maximum flow MF [dppm] of the raw coal and the ash coal shown in Table 2 was measured by a gypsum plastometer method according to JIS-M8801: 2004. The average maximum reflectance Ro [%] was measured in accordance with JIS-M8816: 1992, and the expansion ratio [vol%] was measured according to JIS-M8801: 2004.

When the bulk density of the raw coal was 740 kg / m 3, the reference value W for the unburned coal X of the raw coal was 10.2% by mass. Here, the true specific gravity of the raw coal and the unburned coal is 1.3. Based on this reference value W, the blend amount V [mass%] of the ashless coal to the blended coal was determined as shown in Table 3, and the raw coal and the ashless coal X were mixed to obtain blended coal.

(Carrying process)

The compounded coal was put in a retort forcibly, vibration was applied to the retort, and the packed bulk density was adjusted to 740 kg / m3. Then, the mixture was placed in a double-side heating type electric furnace and then flowed in a nitrogen stream. The carbonization conditions were such that the temperature was raised at 3 ° C / min and then heated at 1000 ° C for 20 minutes. After the carbonization, the retort was withdrawn from the electric furnace and natural-cooled to obtain a coke for blast furnace.

&Lt; Examples 6 to 8 &

The raw coal and the ashless coal Y were blended in the amounts shown in Table 3 in the same procedure as in Examples 1 to 5 except that the ashless coal used was changed to the ashless coal Y in Table 1, Coke for blast furnace was obtained. The reference value W for the ashless coal Y of the raw coal was 17.5 mass%.

&Lt; Examples 9 and 10 >

The raw coal and the non-coal Z were blended in the amounts shown in Table 3 in the same procedure as in Examples 1 to 5 except that the ashless coal used was changed to the ashless coal Z in Table 1, Coke for blast furnace was obtained. The reference value W for the ashless coal Z of the raw coal was 32.9% by mass.

&Lt; Comparative Example 1 &

Various raw materials coal A to E having the characteristics shown in Table 2 as raw coal were each adjusted to 7.5% by mass of water and mixed in a mixing ratio condition 2 shown in Table 2 on the basis of dry coal to prepare raw coal. At this time, the raw coal was pulverized so that the whole (100% by mass) of the raw coal had a maximum diameter of 3 mm or less. Subsequently, without mixing the ashless coal, only the raw coal was carbonized under the same conditions as in Examples 1 to 5 to obtain a coke for blast furnace of Comparative Example 1. [

&Lt; Comparative Example 2 &

The raw coal was obtained by the same method as in Examples 1 to 5 except that the ashless coal was not mixed with the raw coal, and the raw coal was carbonized under the same conditions as those of Examples 1 to 5 to obtain the blast furnace coke of Comparative Example 2.

<Evaluation>

For the blast furnace coke of Examples 1 to 10 and Comparative Examples 1 and 2, the drum strength index DI was measured. Specifically, in accordance with JIS-K2151: 2004, the blast furnace coke was rotated by a drum for 150 rotations, and the blast furnace coke was sieved with a metal plate having an eye size of 15 mm specified in JIS-Z8801-2: 2000, (DI15015) was determined. The strength was determined based on the following criteria.

A: DI> 84.5%, the strength is very good.

B: DI> 83.3%, the strength is excellent.

C: DI 83.3%, the strength drops.

The manufacturing cost of the blast furnace coke of Examples 1 to 10 and Comparative Examples 1 and 2 was determined based on the following criteria.

A: The blending amount of the non-cemented coal E is 10% or more, and the manufacturing cost is low.

B: The blending amount of the non-cemented carbon E is less than 10%, and the manufacturing cost is high.

The results are shown in Table 3.

From Table 3, it can be seen that Examples 1 to 10, in which the blend amount of ashless coal to blended coal was determined by using the reference value W, was more than that of Comparative Example 2 in which no ash is blended and the reference value W is not used And the production cost is lower than that of Comparative Example 1 in which the blending amount of the non-cemented carbon E is small. Accordingly, it can be seen that the method for producing the blast furnace coke can easily and reliably produce the high-strength coke while reducing the manufacturing cost by using the method for determining the blend amount of the ashless coal.

From Table 3, it can be seen from Table 3 that in Examples 1 to 4, Examples 6 to 7, Examples 6 to 7, in which the blend amount of ashless coal to the compounded coal was set to 0.29 W [mass%] or more and 1.00 W 8 to 10 show high strength of the coke obtained in comparison with Comparative Example 2 in which ashless coal is not blended and Example 5 in which the blending amount of ashless coal exceeds 1.00 W [mass%]. From this, it can be understood that the blending amount of the above-mentioned ash is preferably 0.29 W [mass%] or more and 1.00 W [mass%] or less.

In particular, in Examples 1 to 3 and Example 7, Examples 8 and 10, in which the blending amount of the ashless coal was not less than 0.31 W [mass%] and not more than 0.80 W [mass%], Strength equivalent to that of Comparative Example 1 in which the strength is high and the blending amount of the non-coking coal is small. From this, it can be seen that the strength of the coke is further increased by adjusting the blending amount of the ashless coal within the above range.

The present invention includes the following aspects.

Form 1:

A method for determining the amount of ashless coal during the production of a coke for a blast furnace containing an ashless coal and a raw coal obtained by a solvent extraction treatment of coal,

By the reference value W [mass%] calculated by the following formula (1) using the porosity index Pv [vol%] of the raw coal, the exponential index D [vol%] of the ashless coal and the true specific gravity? Wherein the blending amount of the ashless coal to the compounding coal is determined.

&Quot; (1) &quot;

Mode 2:

The method for determining the amount of ashless coal as set forth in aspect 1, wherein the blending amount of the ashless coal to the compounded coal is 0.29 W [mass%] or more and 1.00 W [mass%] or less.

Form 3:

A step of blending the ashless coal obtained by the solvent extraction treatment of coal into the raw coal, and

Step of carburizing the compounded coal

The method of manufacturing a coke for a blast furnace according to claim 1,

The method for producing a coke for a blast furnace according to claim 1, wherein in the blending step, the blending amount of the ashless coal in the blended coal is determined by using the method for determining the blending amount of ashless coal according to form 1 or 2.

This application is accompanied by a priority claim based on Japanese Patent Application No. 2014-206767 filed on October 7, 2014. Japanese Patent Application No. 2014-206767 is incorporated herein by reference.

INDUSTRIAL APPLICABILITY As described above, the method for determining the amount of ashless coal in the present invention can efficiently determine the blending amount of the unburned coal at the time of manufacturing the blast furnace coke, so that the production method of the blast furnace blending method using this method High-strength coke can be easily and reliably produced while reducing the amount of coke.

1: Strong cohesive particles
1a: Continuous phase
2: Non-sparkling carbon particles
2a: Modified component
4:
4a: Continuous phase
10: Roche
A: Bubble
B: Large defect

Claims (3)

A method for determining the amount of ashless coal during the production of a coke for a blast furnace containing an ashless coal and a raw coal obtained by a solvent extraction treatment of coal,
By the reference value W [mass%] calculated by the following formula (1) using the porosity index Pv [vol%] of the raw coal, the exponential index D [vol%] of the ashless coal and the true specific gravity? Wherein the blending amount of the ashless coal to the compounded coal is determined.
&Quot; (1) &quot;

The method for determining the amount of ashless coal according to claim 1, wherein the amount of the ashless coal to be blended is set to 0.29 W [mass%] or more and 1.00 W [mass%] or less. A step of blending the ashless coal obtained by the solvent extraction treatment of coal into the raw coal, and
Step of carburizing the compounded coal
The method of manufacturing a coke for a blast furnace according to claim 1,
The method for producing a coke for a blast furnace according to claim 1, wherein in the blending step, the amount of the ashless coal to be blended is determined by using the method for determining the blend amount of ashless coal according to claim 1.

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