JP5151490B2 - Coke production method - Google Patents

Description

  The present invention relates to a method for producing coke, and specifically relates to a method for producing coke by pulverizing a caking additive used as a raw material for coke.

In order to ensure stable air permeability in the blast furnace, it is desirable that the blast furnace coke charged as a reducing material in the furnace has high strength. In addition, in order to perform operation with a low reducing material ratio aiming at reduction of exhausted CO ₂ in a large blast furnace in recent years, blast furnace coke is required to have higher strength. In order to increase the strength of coke, it is effective to use high-quality caking coal as a raw material.

  Because this high-quality caking coal has problems such as being expensive and having a low abundance in terms of resources, the raw material for coke contains as much low-quality and inexpensive non-caking coal as possible. I have to. However, since the strength of coke is reduced when a large amount of non-microcoking coal is blended, it is against the request to increase the strength of coke for blast furnace (hereinafter also referred to simply as “strength”).

  Therefore, in order to compensate for the decrease in caking caused by blending a large amount of non-slightly caking coal, for example, a caking material made of asphalt pyrolysis pitch is blended. That is, the lack of caking property and the decrease in coke strength caused by blending a large amount of non-slightly caking coal are compensated by blending this caking material. Moreover, the mixing | blending of a caking additive can fully compensate for the fall of intensity | strength, and when the margin arises in an intensity | strength, the compounding quantity of good quality caking coal can be reduced.

As described above, coke for blast furnace is produced by blending non-slightly caking coal as much as possible into high-quality caking coal as a coke raw material, and further blending a caking additive.
The coke raw material is pulverized to a desired particle size in advance and then charged into the coke oven. Usually, the particle size of the raw material is controlled at a particle mass ratio of 3 mm or less, and the value is generally about 70 to 80%. However, JIS method sieves that specify the test method for coals do not have a mesh opening of 3 mm, and the closest opening is 2.8 mm. The particle size distribution of the pulverized coal is often expressed by a distribution function (Rosin-Rammler equation) proposed by Rosin-Rammeler. Under normal particle size control, the equivalent number n in the Rosin-Rammler equation is about 0.7. Under this normal particle size control, when the particle ratio of 2.8 mm or less is read as the particle ratio of 3 mm or less by the Rosin-Rammler equation, the particle ratio of 3 mm or less is about 1 to 2% larger than the particle ratio of 2.8 mm or less. Value.

  And the crushing of the raw material for coke is generally (a) a method of crushing in a lump after mixing coal to be fed to a coke oven and a caking additive, and (b) several types classified based on the properties of the coal. It is carried out by any of the methods in which the caking agent is mixed with any of the coal groups and then pulverized.

  As described above, the role of the binder in the production of coke for blast furnace is to compensate for the decrease in the strength of coke caused by poor non-slightly caking coal, and during the charging to the coke oven, The smaller the particle size, the greater the effect of improving the strength of coke. For this reason, when mix | blending the same kind of raw material, high intensity | strength of coke can be achieved by grind | pulverizing a caking additive finely. In other words, it is possible to increase the amount of non-slightly caking coal by reducing the amount of expensive caking coal by the amount of increase in coke strength by finely grinding the caking material. It is desirable to finely pulverize the binder. For this reason, the invention regarding the grinding | pulverization of a caking additive is disclosed until now.

Patent Document 1 discloses an invention relating to a method in which only a binder is pulverized alone and mixed with pulverized coal for blending.
Furthermore, Patent Document 2 discloses that the strength of coke can be increased in accordance with reducing the average particle size of the binder to 4.6 mm, 2.4 mm, or 0.8 mm, and that the binder is made of coal. It is disclosed that the average particle size of coal is 4.6 mm or less when pulverized together.
JP 2007-002052 A JP 2007-016186 A

  However, in order to implement the invention disclosed in Patent Document 1, it is necessary to separately provide equipment for pulverizing only the binder, and it is necessary to provide equipment such as a mixer for uniformly mixing with coal. Equipment costs increase.

  Further, in order to sufficiently improve the strength with the binder according to the invention disclosed in Patent Document 2, it is not sufficient that the average particle diameter of coal is 4.6 mm or less, and the binder is as fine as possible. It is desirable to grind. However, generally, the power required to pulverize the material to be pulverized so that the particle size of the material to be pulverized becomes finer. In order to pulverize to a certain particle size or less, the pulverized fine particles act as a buffer material at the time of pulverization impact, and the power required for pulverization is remarkably increased. For this reason, when the target particle size of the material to be crushed is equal to or smaller than this particle size, it is necessary to newly provide a dedicated facility for pulverizing the particle size to be smaller than this particle size. .

  Thus, in the production of coke, particularly coke for blast furnaces, the desired average particle size of the binder is obtained without newly providing a facility for crushing the binder to be blended with coal into the desired average particle size. The following is required to grind.

  The inventors of the present invention have made extensive studies to solve the above-described problems, and have focused on the difference in coal grindability (HGI). A hard glove grindability index (HGI) is generally used as an index representing the grindability of coal as a raw material. HGI is an evaluation index for grindability described in JIS M 8801 (coals-test method), and the higher the HGI, the better the grindability.

  And when mixing and pulverizing a caking additive with coal, based on the average HGI of the coal to mix, the particle size after crushing of the mixture of caking additive and coal is adjusted or determined, and the particle size after crushing adjusted or determined If the mixture is pulverized so that it becomes, it is possible to finely pulverize the binder to a desired particle size or less without newly installing a facility for pulverizing the binder to the desired particle size. As a result, the present invention was completed.

In the present invention, asphalt pyrolysis pitch as a binder is mixed with one or more kinds of coal having an average HGI of 85 or less, and then the mixture of the binder and coal is based on the average HGI of the coal. Adjusting the particle size after pulverization, and including a step of pulverizing the mixture so as to obtain the adjusted particle size after pulverization; and, when the average HGI is 65 or less, particles of 2.8 mm or less after pulverization of the mixture When the average HGI is greater than 65 and less than or equal to 75, so that the particles of 2.8 mm or less after pulverization of the mixture is greater than 75% by mass. When the average HGI is greater than 75 and less than or equal to 85, the particle size after pulverization is adjusted so that particles of 2.8 mm or less after pulverization of the mixture are greater than 85% by mass. A coke manufacturing method of a.

  In the present invention, after the binder is mixed with one or more kinds of coal, the particle size after pulverization of the mixture of the binder and coal is determined based on the average HGI of the coal, and after the determined pulverization A method for producing coke, comprising a step of pulverizing a mixture so as to have a particle size.

  In these present inventions, “HGI” means a hard glove grindability index, which is a grindability evaluation index defined by JIS M 8801 (coals—test method). In the present invention, the “particle size after pulverization” means a mass ratio of particles of 2.8 mm or less.

  In other words, the present invention is a method of pulverizing a binder after mixing it with one or more types of coal, and based on the average HGI of the coal mixed with the binder, the binder and coal The particle size of the mixture is adjusted or determined, and the mixture is pulverized so as to have the adjusted or determined particle size after pulverization.

Here, it supplements about the invention specific matter in this invention "Based on the average HGI of coal ... Adjusting the particle size after grinding | pulverization of a mixture ...".
A supplementary explanation will be given regarding the typical coal crushing process in the steel industry. The pulverization of coal includes pulverization of raw material coal for coke and pulverization for pulverized coal blown from a blast furnace tuyere. As is understood from the fact that the hard glove grindability index HGI is defined in JIS as a test method for coal, it is a well-known matter for those skilled in the art to consider HGI when crushing coal.

  As described above, the coke raw material needs to be pulverized to a desired particle size in advance. In order to control the particle size, the properties to be studied for coal include pulverization properties (hardness and softness of coal) along with the particle size and moisture before pulverization, and HGI is typically used as an indicator of pulverization properties. On the other hand, on the pulverizer side, adjustment of the number of rotations such as the pulverization gap and the rotor (specific operation contents differ depending on the type of the pulverizer). In addition, there is a coal throughput as an operating factor across both the coal and the pulverizer.

  For this reason, in the present invention, the invention specific matter “based on the average HGI of coal ... adjusting the particle size after pulverization of the mixture ...” is based on coal conditions such as the average HGI of coal. It means that a target particle size after pulverization is obtained by operating a pulverizer by appropriately combining a plurality of operating factors including a processing amount.

  According to the present invention, when producing coke, particularly coke for blast furnace, the caking material is reduced to a desired particle size or less without newly providing a facility for pulverizing the caking material to be blended with coal into a desired particle size. It can be crushed. For this reason, since the effect of improving the strength of coke possessed by the caking additive can be sufficiently obtained, the amount of expensive caking coal required for satisfying a predetermined coke strength is suppressed and an inexpensive non-fine effect is obtained. The blending ratio of caking coal can be increased, and thereby, coke having a desired high strength can be produced at a low cost.

The best mode for carrying out the method for producing coke according to the present invention will be described below in detail with reference to the accompanying drawings.

First, the principle of the present invention will be briefly described.
In general, considering the case where a single coke raw material is pulverized with the same power, a coke raw material with good pulverization is more easily pulverized than a coke raw material with poor pulverization, so it is finely pulverized. Is done. This is true even when two or more brands of coke raw materials are mixed and pulverized. When coke raw materials with relatively good pulverizability are mixed and pulverized with respect to coke raw materials with poor pulverization properties, Excessive power acts on the coke raw material with good properties, so the coke raw material with good grindability is finely ground.

  Generally, caking materials have better grindability compared to coal, so by mixing with coal with poor grindability and grinding, dedicated equipment for fine grinding for the same reason as described above. The caking material can be finely pulverized without newly providing.

  Furthermore, when the pulverization property of coal mixed with the binder is relatively good, the binder can be finely pulverized by setting the particle size to be pulverized smaller. In other words, in the case of pulverizing after mixing the binder with coal having poor pulverizability, the particle size after pulverization may be coarse to obtain the desired particle size of the binder, but conversely, coal having good pulverizability. In the case of pulverization after mixing with, it is possible to obtain a desired binder particle size by setting the particle size after pulverization more finely.

  Thus, when this mixture is pulverized after mixing the caking additive with one or more kinds of coal, the average value of the hard glove grindability index (average HGI), which is an index representing the pulverizability of this coal. ) To adjust or determine the particle size after pulverization of the mixture (that is, the mass ratio of particles of 2.8 mm or less), and the adjusted or determined particle size after pulverization (that is, the mass ratio of particles of 2.8 mm or less). It is effective to grind the mixture in such a manner.

  Specifically, when (A) coal and a binder having an average HGI ≦ 65 are mixed and then pulverized, pulverization is performed so that particles of 2.8 mm or less are larger than 70% in mass ratio, B) In the case of pulverizing after mixing coal and binder with 65 <average HGI ≦ 75, pulverization is performed so that particles of 2.8 mm or less are larger than 75% by mass ratio, (C) 75 < When the coal having an average HGI ≦ 85 and the binder are mixed and then pulverized, it is desirable to pulverize particles having a particle size of 2.8 mm or less to be greater than 85% by mass.

  In addition, it is desirable that the upper limit of the average HGI of coal mixed with the binder is 85 or less. That is, in pulverization with coal having a large average HGI, it is necessary to make the mass ratio of particles of 2.8 mm or less after pulverization greater than at least 85% in order to reduce the binder to 1 mm or less. However, generally, HGI of caking coal is large, and excessive crushing of caking coal is not desirable because it causes a decrease in coke strength after dry distillation. Therefore, it is desirable that the upper limit of the average HGI of coal to be mixed is 85 or less so that most of the caking coal is removed.

  The coke raw material thus pulverized is then charged into a coke oven and dry-distilled by a well-known and commonly used technique to produce coke. For this reason, according to this Embodiment, the blast furnace coke which has desired high intensity | strength can be manufactured at low cost.

Furthermore, the present invention will be described more specifically with reference to examples.
As a result of investigations by the present inventors, it has been found that the particle size after pulverization of the binder which significantly increases the power required for pulverizing the binder is 1 mm.

  Therefore, paying attention to the difference in coal grindability (HGI), when the binder is mixed with coal and pulverized, it is finely pulverized by adjusting the particle size after pulverization based on the average HGI of the coal to be mixed. For this reason, a method for crushing the binder to 1 mm or less was examined without newly providing a dedicated facility.

  Table 1 shows the average HGI of the samples A to L and the blending breakdown of the eight coal types a to h. Twelve types of samples A to L having different average HGI were prepared using the coal types a to h in Table 1.

  Further, as the binder, an asphalt pyrolysis pitch having a sulfur content of about 6.5 mass% and an HGI of about 140 was used. Asphalt pyrolysis pitch is a typical caking material, but the reason for using asphalt pyrolysis pitch as caking material in this example is that the sulfur content of the asphalt pyrolysis pitch is as high as about 10 times that of coal. Therefore, by analyzing the sulfur content in the mixture of the binder and coal, it is possible to accurately calculate the abundance ratio of the binder in the mixture of binder and coal.

  In this example, the binders were mixed with each sample A to L in an external number of 5% by mass, and then pulverized into various particle sizes. And sieving after pulverization, the average particle size of the binder after pulverization by comparing the content of the binder for each sieve mesh with the case of pulverizing without adding the binder for the sulfur content The diameter was estimated.

  The relationship between the average particle size of the binder after pulverization and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less as the particle size after pulverization was examined. The mass ratio of particles having a particle size of 2.8 mm or less was a mass ratio that passed through a sieve having a sieve size of 2.8 mm with respect to the entire mixture of the binder and the coal after pulverization. As a result, it was possible to clarify the relationship between the average HGI of coal and the particle size after pulverization, in which the average particle size of the binder was 1 mm or less.

  Table 2 shows that the mass ratio of particles of 2.8 mm or less (−2.8 mm%) is around 70% when a mixture obtained by mixing a binder with samples A to D having an average HGI of 65 or less is crushed. The results are shown. FIG. 1 is a graph plotting the relationship between the estimation result of the average particle size of the binder and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization.

  As shown in the graph of FIG. 1, in mixing with coal having an average HGI of 65 or less, pulverization is performed so that the mass ratio of particles of 2.8 mm or less (−2.8 mm%) is at least 70% or more. Thus, the average particle size of the binder can be reduced to 1 mm or less.

  Next, Table 3 shows a mass ratio (−3 mm%) of particles of 2.8 mm or less when a mixture obtained by mixing a binder with samples E to H having an average HGI of greater than 65 and 75 or less is pulverized. Shows a result of around 75%. FIG. 2 is a graph plotting the relationship between the estimation result of the average particle diameter of the binder and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization.

  As shown in the graph of FIG. 2, in mixing with coal having an average HGI greater than 65 and less than or equal to 75, the mass ratio of particles less than or equal to 2.8 mm (−2.8 mm%) is at least 75% or more. By crushing, the average particle diameter of the binder can be reduced to 1 mm or less.

  Further, Table 4 shows a mass ratio of particles of 2.8 mm or less (−2.8 mm%) when a mixture obtained by mixing a binder with samples E to H having an average HGI of greater than 75 and 85 or less is pulverized. ) Shows a result of around 85%. FIG. 3 is a graph plotting the relationship between the estimation result of the average particle size of the binder and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization.

  As shown in the graph of FIG. 3, in mixing with coal having an average HGI greater than 75 and less than or equal to 85, the mass ratio of particles less than or equal to 2.8 mm (−2.8 mm%) is at least 85% or more. By crushing, the average particle diameter of the binder can be reduced to 1 mm or less.

FIG. 1 shows the relationship between the estimation result of the average particle size of a binder mixed with coal having an average HGI of 65 or less and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization. This is a plotted graph. FIG. 2 shows the estimation result of the average particle size of the binder mixed with coal having an average HGI of more than 65 and less than 75 and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization. It is the graph which plotted the relationship. FIG. 3 shows the estimation result of the average particle size of the binder mixed with coal having an average HGI of more than 75 and less than 85 and the mass ratio (−2.8 mm%) of particles of 2.8 mm or less after pulverization. It is the graph which plotted the relationship.

Claims (1)

After mixing the asphalt pyrolysis pitch as a binder with one or more types of coal having an average HGI of 85 or less, the particle size after pulverization of the mixture of the binder and coal is determined based on the average HGI of the coal. Adjusting and adjusting the adjusted pulverized particle size to include the step of pulverizing the mixture, and when the average HGI is 65 or less, the particles of 2.8 mm or less after pulverization of the mixture have a mass When the average HGI is greater than 65 and less than or equal to 75 so that the ratio is greater than 70%, the average so that particles 2.8 mm or less after pulverization of the mixture is greater than 75% by mass When the HGI is greater than 75 and less than or equal to 85, the particle size after pulverization is adjusted so that particles of 2.8 mm or less after pulverization of the mixture are greater than 85% by mass. Manufacturing method of coke.

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