JP6716874B2 - Blast furnace coke manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing blast furnace coke, and more particularly to a method for producing blast furnace coke using inferior coal coated with caking coal.

In blast furnace operation, in order to efficiently heat and reduce agglomerated iron ore, agglomerated iron ore or agglomerates of iron-making dust to produce pig iron, generate CO-reducing gas and ensure aeration of reducing gas Coke is charged into the blast furnace as a spacer for this purpose.

In order for the blast furnace coke to exert its full effect as a spacer in the blast furnace, it must have sufficient strength to prevent it from collapsing due to impact during charging into the blast furnace or load loading of the charge inside the blast furnace. Required. On the other hand, since high-quality coking coal as a raw material for coke is in a resource-depleted state, many methods have been proposed for producing coke having necessary strength by using poor quality coal.

As a method of producing coke having the required strength using inferior coal, a method of increasing the charging density of the charging coal into the coke oven, a method of adding a binder such as tar to the charging coal, and crushing of coal There is a method of adjusting the particle size and mixing, and how to mix it with good quality coking coal is being studied.

In the method of adjusting the crushing particle size of coal and blending it, the caking coal is roughly crushed and the poor quality coal with a large amount of inert is finely crushed to improve the caking property of the raw coal during carbonization. , Has improved coke quality. On the other hand, if the grain size of the poor quality coal becomes fine, the coke strength may decrease, so there is also a technique for making the grain size of the poor quality coal coarse.

In this regard, in Patent Document 1, sufficient coke strength may not be obtained only by coarsening the grain size of inferior coal, and it is because coarse grain size of inferior coal causes coarse coke strength and coke coking coal to be obtained. It is described that the size of both particles of the above is similar, and as a result, the particles come into point contact with each other, resulting in insufficient compatibility (compatibility) between the poor quality coal and the coking coking coal. ..

Therefore, in Patent Document 1, 0.01 mm of coal that is compatible with coke raw coal and has a cohesion index of 75% or more, a volatile content of 15 to 35%, and a maximum fluidity of logddpm 2.0 to 4.5. Less than 30%, and 0.01 to 1.0 mm of particle size is adjusted to 50% or more by caking coal to cover the particle surface of inferior coal and mix it with coke raw coal to produce inferior coal. A technique for improving compatibility with coke coking coal and obtaining sufficient coke strength is disclosed.

However, in the technique disclosed in Patent Document 1, since the poor quality coal and the coking coal that improves the compatibility with the coke coking coal are simply mixed and brought close to each other, the viscosity of the poor quality coal from the surface of the poor quality coal may be increased during the transportation process. There was a problem that the coal was peeled off, and as a result, the effect of improving the compatibility with the coke raw coal was not sufficiently obtained.

Further, in Patent Document 1, the ratio of the poor quality coal to the coking coal that improves the compatibility with the coke raw coal is set to 1.0 or 1.5, but the ratio of the cheap poor quality coal to the coke raw coal is set to 1.0. From the demand of increasing, it is desirable to increase the ratio of poor quality coal to exhibit the same effect. However, in the technique disclosed in Patent Document 1, since the caking coal is peeled off from the surface of the poor quality coal during the transportation process or the like, the amount of the caking coal that is peeled off is taken into consideration, Even if the amount of charcoal is increased, that is, the ratio of inferior coal to caking coal is decreased, it is difficult to increase the ratio of inferior coal to caking coal.

JP, 07-157769, A

In view of the above-mentioned conventional state of the art, the present invention can suppress the peeling of caking coal that improves the compatibility with coke raw coal in the transportation process and the like, and further, with the coke raw coal, It is an object of the present invention to provide a method for producing coke using inferior coal coated with coking coal, which can increase the ratio of inferior coal to coking coal that improves the compatibility of the above.

The present inventors diligently studied a method for solving the above problems. In Patent Document 1, in a method of supplementing a binder such as a bituminous substance, the bituminous substance is not always the same as the quality of coal, a homogeneous coke cannot be obtained, and an excessive addition of the bituminous substance causes expansion. It is described that the poor quality coal is coated with a coking coal which improves the compatibility with the coking raw coal because it has a defect that it accelerates and adversely affects the coke strength.

On the other hand, the inventors of the present invention, inferior coal, and the fine powder caking coal to improve the compatibility with coke raw coal, when a liquid binder such as bituminous was added and kneaded, from the surface of the inferior coal It has been found that a caking coal-coated poor quality coal can be obtained which can suppress the peeling of fine powder caking coal and can increase the ratio of the poor quality coal to the caking coal. Furthermore, it was found that the coke produced by using the poor quality coal coated with this coking coal has sufficient strength.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) Cohesion index is less than 50%, less than 0.1 mm is 10% or less, 0.1-5.0 mm is adjusted to a particle size of 70% or more, and cohesion index is 75. % Or more, volatile matter is 15 to 35%, maximum fluidity is logddpm 2.0 to 4.5, and 0.6 mm or less is fine powder coking coal adjusted to a particle size of 70% or more, and further 0.06 mm. following addition of ultrafine powder caking coal which is adjusted to 70% or more of particle size, 3 to 26 mass outside number content of liquid binder to the total of the ultrafine caking coal and the pulverized caking coal % Of the liquid binder, and after kneading them, or after kneading and molding, the coke raw coal is added to the coke raw coal in an amount of 1 to 40% by mass of inferior coal. A method for producing coke for a blast furnace, which comprises:
(2) The ultrafine powder caking coal is contained in an amount of 1 to 10% by mass with respect to the total amount of the fine powder caking coal and the ultrafine powder caking coal. Method for manufacturing blast furnace coke.
(3) The liquid binder and the ultrafine powder so that the content Y (mass%) of the liquid binder and the content X (mass%) of the ultrafine powder caking coal satisfy the following formula (1). Caking coal is added, The manufacturing method of the blast furnace coke as described in said (1) or (2) characterized by the above-mentioned.
(−5/4)×X+8≦Y≦(6/10)×X+20 (1)

ADVANTAGE OF THE INVENTION According to this invention, peeling of the coking coal which improves the compatibility with coke raw material coal can be suppressed from the surface of inferior coal, and also even if cheap inferior coal is mix|blended with caking coal in large quantities. It is possible to produce good quality blast furnace coke.

It is a figure which shows the flow which mixes and granulates by adding a liquid binder to inferior coal and a pulverized caking coal. It is a figure which shows the relationship between the content rate of a liquid binder, and the content rate of an ultrafine powder caking coal.

Hereinafter, a method for producing the blast furnace coke of the present invention (hereinafter referred to as the production method of the present invention) will be described. In the following, the content rate (mass %) of the liquid binder with respect to the fine caking coal and the content rate (mass %) of the liquid binder with respect to the total of the fine caking coal and the ultrafine caking coal are outside numbers. The content (mass %) of the ultrafine powder caking coal with respect to the total of the fine powder caking coal and the ultrafine powder caking coal is shown by the number inside.

The present inventors can suppress the peeling of caking coal (hereinafter, referred to as “fine powder caking coal”) that improves the compatibility with the coke raw coal from the surface of the poor quality coal, and further, for fine powder caking coal, A method for producing inferior coal coated with fine powder caking coal, which can increase the ratio of inferior coal, was examined.

In Patent Document 1, in a method of supplementing a binder such as a bituminous substance, the bituminous substance is not always the same as the quality of coal, a homogeneous coke cannot be obtained, and an excessive addition of the bituminous substance causes expansion. It is described that the poor quality coal is coated with a coking coal which improves the compatibility with the coking raw coal because it has a defect that it accelerates and adversely affects the coke strength.

Then, even for a mixture of inferior coal and pulverized caking coal, when a liquid binder such as a bituminous material is added, it is considered that the coke strength is reduced. It was thought that by adding a liquid binder to the charcoal and kneading, it is possible to suppress the peeling of the fine cohesive coal from the surface of the poor quality charcoal.

Therefore, the following test was conducted. Less than 0.1 mm is 10%, 0.1-5.0 mm is 70%, 5.0 mm is less than 20% adjusted to a particle size of poor quality coal, cohesion index is 75% or more, volatile matter is 15- 35%, the maximum fluidity was logddpm 2.0-4.5, and 0.6 mm or less of fine powder caking coal adjusted to a particle size of 90% was prepared.

In order to have a ratio of inferior coal to pulverized coking coal of 2.5, inferior coal and pulverized cohesive coal are mixed, and the mixture is in a liquid state so as to be 14 mass% with respect to pulverized cohesive coal. A binder (tar) was added and kneaded to obtain a test kneaded product 1. After that, the test kneaded material 1 was blended so that the mass of the poor quality coal was 10% by mass with respect to the coke raw material coal, and the mixture was dry-distilled to produce the test coke 1.

For comparison, inferior charcoal adjusted to a particle size of 10% less than 0.1 mm, 70% 0.1 to 5.0 mm, and 20% more than 5.0 mm, and a cohesion index of 75% or more and volatilization. 15 to 35% of content, maximum fluidity is logddpm 2.0 to 4.5, and 0.6 mm or less prepares fine cohesive coal adjusted to a particle size of 90%. Inferior coal and fine cohesive coal were mixed without adding a liquid binder (tar) so that the ratio was 2.5, and a test mixture 1 was obtained. Then, the test mixture 1 was blended with the same coke raw coal as described above so that the mass of inferior coal was 10% by mass, and the mixture was subjected to dry distillation to produce a test coke 2.

When the peeling of the fine cohesive coal from the surface of the poor quality coal was investigated by applying an impact to the test kneaded product 1 and the test mixture 1, the test kneaded product 1 showed that the fine powder caking coal was peeled from the surface of the poor quality coal. Although not observed, in the test mixture 1, fine cohesive coal was peeled off from the surface of the poor quality coal.

Next, the coke strength (cold strength, strength after hot reaction) of the test cokes 1 and 2 was measured. As for the cold strength (DI), after the coke was rotated 150 times by a drum tester described in JIS K2151, the percentage DI ¹⁵⁰ ₁₅ of the coke on a 15 mm sieve was measured. Regarding the strength (CSR) after hot reaction, 200 g of coke having a particle size of 20 mm was reacted with CO ₂ gas at a high temperature of 1100° C. for 2 hours, and then the rotational strength was measured by an I-type drum.

The cold strength DI of the test coke 1 was 86.0%, the post-hot reaction strength CSR was 58%, and the cold strength DI of the test coke 2 was 79.5%, the post-hot reaction strength. The CSR was 50%, and the test coke 1 had higher coke strength than the test coke 2.

From this, inferior coal and pulverized caking coal, a kneaded product obtained by kneading by adding a liquid binder, from the surface of the inferior coal, peeling of the pulverized caking coal is suppressed, and when coke is produced using this kneaded product. It was found that coke having sufficient strength can be obtained. In addition, the ratio of inferior coal to fine cohesive coal was set to 2.5, and it was also found that inexpensive inferior coal can be mixed in a large amount with respect to caking coal.

Incidentally, the upper limit of the ratio of inferior coal to fine cohesive coal is not particularly specified, fine cohesive coal covers the particle surface of inferior coal, the effect of improving the compatibility with coke raw coal is sufficient. A higher ratio is more preferable as long as it can be obtained, and for example, 4.0 can be mentioned.
Moreover, when the ratio of inferior coal to fine cohesive coal is set, the mass of inferior coal to coke coking coal will be 1 to 40% by mass, depending on this ratio, as described below. The properties and blending amount will be adjusted.

Next, in order to investigate the relationship between the addition amount of the liquid binder, the peeling of the fine cohesive coal from the surface of the poor quality coal, and the coke strength, the following test was performed. The test is a test similar to the above, inferior coal and fine cohesive coal used in the above test were mixed so that the ratio of inferior coal to fine cohesive coal was 2.5, and the resulting mixture Various amounts of the liquid binder (tar) were added to the fine powder caking coal and kneaded to obtain a test kneaded product. Then, the test kneaded product was blended with the coke raw coal so that the mass of the poor quality coal was 10% by mass, and the mixture was dry-distilled to produce a test coke.

As a result of the test, by adding 8 to 20% by mass of the liquid binder, it is possible to suppress the peeling of the fine powder caking coal from the surface of the poor quality coal, and by producing coke using this kneaded product, It was found that coke having sufficient strength can be obtained.

Further, it is preferable that the addition amount of the binder can be freely changed according to the prices of the poor quality coal and the binder. Therefore, the inventors of the present invention can suppress the peeling of the fine cohesive coal from the surface of the inferior coal even if the amount of the liquid binder is decreased or increased, and obtain a sufficient coke strength when carbonized. The kneaded material to be used was examined.

When the amount of liquid binder is small with respect to inferior coal and pulverized caking coal, the bridging force between the inferior coal and pulverized caking coal is weakened, and the pulverized caking coal is peeled off from the surface of the inferior coal, Since coke strength may not be obtained, it was considered to increase the bridging force between coals.

Further, when the amount of the liquid binder is large with respect to the inferior coal and the pulverized caking coal, the kneaded product is softened by the excess liquid binder and the strength cannot be maintained. Since it becomes impossible to maintain the strength due to the adherence of, it was considered to absorb or absorb an excess liquid binder.

The inventors of the present invention investigated the means therefor, and then conceived that in addition to the liquid binder, in addition to the liquid binder, the ultrafine powder caking coal was added to the poor quality coal and the fine caking coal. That is, it was considered that when the amount of the liquid binder was small, the ultrafine powder caking coal filled the voids between the inferior coal and the fine powder caking coal to bond the coal particles by the solid crosslinking force. When the amount of the liquid binder is large, the ultrafine powder caking coal absorbs or absorbs part of the liquid binder due to the large specific surface area of the ultrafine coal, and the excess liquid binder oozes on the surface of the kneaded product. I thought it wouldn't.

Therefore, the following test was conducted. Less than 0.1 mm is 10%, 0.1-5.0 mm is 70%, 5.0 mm is less than 20% adjusted to a particle size of poor quality coal, cohesion index is 75% or more, volatile matter is 15- 35%, the maximum fluidity was logddpm 2.0-4.5, and 0.6 mm or less of fine powder caking coal adjusted to a particle size of 90% was prepared.

First, when the amount of the liquid binder is small, the poor quality coal and the fine quality caking coal are mixed so that the ratio of the poor quality coal to the fine quality caking coal is 2.5, and 0.06 mm or less is 70%. The ultrafine cohesive coal adjusted to the particle size of was mixed so as to be 5% by mass with respect to the total of the fine cohesive coal and the ultrafine cohesive coal. A liquid binder (tar) was added to this mixture so as to be 5% by mass based on the total amount of the fine cohesive coal and the ultrafine cohesive coal, and the mixture was kneaded to obtain a test kneaded product 2. Then, the test kneaded product was blended with the same coke raw coal as described above so that the mass of the inferior coal was 10% by mass, and the mixture was subjected to dry distillation to produce a test coke 3.

Next, when the amount of the liquid binder is large, the fine cohesive coal and the poor coal used in the production of the test coke 3 are inferior coal so that the ratio of the poor coal to the fine cohesive coal is 2.5. 5% by mass based on the total amount of the fine cohesive coal and the ultrafine cohesive coal, in which 0.06 mm or less is adjusted to a particle size of 70%. Mixed so that A liquid binder (tar) was added to this mixture so as to be 24% by mass with respect to the total amount of the fine cohesive coal and the ultrafine cohesive coal, and the mixture was kneaded to obtain a test kneaded product 3. Then, the test coke 4 was manufactured by adding the test kneaded material to the same coke raw coal as described above so that the mass of the inferior coal was 10% by mass, and carrying out dry distillation.

As a reference object, a test obtained by kneading the above-mentioned fine powder caking coal and poor quality coal with a liquid binder (tar) added so as to be 14% by mass, and without adding ultrafine powder caking coal. A test coke 1 produced by blending the kneaded product 1 and the coke raw material carbon with the test kneaded product 1 and carrying out dry distillation was used.

When the peeling of the fine cohesive coal from the surface of the inferior coal was investigated by applying an impact to the test kneaded product 2 and the test kneaded product 3, it was found that the test kneaded product 2 and the test kneaded product 3 were fine powder from the surface of the inferior coal. No peeling of caking coal was observed.

Next, the cold strength DI and the post-hot reaction strength CSR of the test coke 3 and the test coke 4 were measured. The cold strength DI of the test coke 3 was 86.5%, the post-hot reaction strength CSR was 60%, and the cold strength DI of the test coke 4 was 86.0%, the post-hot reaction strength. The CSR was 70%. On the other hand, as described above, the cold strength DI of the test coke 1 is 86.0%, the strength CSR after hot reaction is 58%, and the test coke 3 and the test coke 4 are Coke strength increased.

From this, when the liquid binder is added to the inferior coal and the fine cohesive coal and kneaded to obtain a kneaded product, by adding the ultrafine cohesive coal, even if the amount of the liquid binder is reduced, The fine cohesive coal fills the voids between the inferior coal and the fine cohesive coal, and bonds the coal particles by the solid cross-linking force, so that the peeling of the fine cohesive coal can be suppressed from the surface of the inferior coal. In addition, even if the amount of liquid binder is increased, the ultrafine powder caking coal adsorbs or absorbs a part of the liquid binder and does not allow excess liquid binder to ooze to the surface of the kneaded product. Peeling of fine cohesive coal can be suppressed from the surface. And, it was found that the strength of the coke produced using this kneaded product was about the same as or higher than that of the coke produced using the kneaded product prepared without adding the ultrafine powder caking coal. ..

In addition, in order to investigate the relationship between the amount of the liquid binder added and the content of the ultra-fine coking coal, the peeling of the fine coking coal from the surface of the inferior coal, and the coke strength. The following tests were conducted.

The test is a test similar to the above, mixing the inferior coal and the fine cohesive coal used in the above test so that the ratio of the inferior coal to the fine cohesive coal is 2.5, Baking coal was mixed so as to have various contents with respect to the total amount of the fine cohesive coal and the ultrafine cohesive coal, and the resulting mixture was added to the total amount of the fine cohesive coal and the ultrafine cohesive coal. Various amounts of liquid binder (tar) were added and kneaded to obtain test kneaded products. Then, the test kneaded product was blended with the coke raw coal so that the mass of the poor quality coal was 10% by mass, and the mixture was dry-distilled to produce a test coke.

As a result of the test, the addition amount of the liquid binder was 3 to 26 mass with respect to the total amount of the fine cohesive coal and the superfine cohesive coal by including the ultrafine cohesive coal in the poor quality coal and the fine cohesive coal. It was also found that, even when the percentage is %, it is possible to suppress peeling of the fine cohesive coal from the surface of the poor quality coal, and to obtain coke having sufficient strength.

Further, by adding 1 to 10% by mass of the ultrafine powder caking coal to the total of the fine powder caking coal and the ultrafine caking coal, even if the amount of the liquid binder is reduced, it is possible to obtain fine powder from the surface of the poor quality coal. It was found that the caking coal can be prevented from peeling and coke having sufficient strength can be obtained.

The summary of the examination results is as follows.
A liquid binder is added to inferior coal and fine cohesive coal in a proportion of 8 to 20% by mass with respect to fine cohesive coal, and the mixture is kneaded, blended with coke raw coal, and carbonized to produce coke. Thus, it is possible to suppress the peeling of fine cohesive coal from the surface of inferior coal, and further add ultrafine cohesive coal to inferior coal and fine cohesive coal to make the total of fine cohesive coal and ultrafine cohesive coal On the other hand, by adding and kneading the liquid binder so as to be 3 to 26% by mass, it is possible to suppress the peeling of the fine powder caking coal from the surface of the poor quality coal. Then, the obtained kneaded product is blended with the coke raw material carbon, and the carbonization is carried out to produce coke, whereby coke having sufficient strength can be obtained.

The manufacturing method of the present invention has reached the inventions described in (1) to (3) above through the above-described examination process.

[Basic form]
Next, the manufacturing method of the present invention will be specifically described with reference to a flow chart. FIG. 1 shows a flow of kneading and granulating by adding a liquid binder to inferior coal and fine caking coal.

Inferior coal having a cohesive strength index of less than 50% is put in the inferior coal hopper 1, and a predetermined amount of inferior coal is put in the crusher 2. In the pulverizer 2, the inferior carbon is pulverized to a particle size of less than 0.1 mm, 10% or less, 0.1 to 5.0 mm, 70% or more, and more than 5.0 mm, 20% or less. The crusher 2 is not particularly limited, and one that can be crushed to the above particle size can be used. The crushed inferior coal is conveyed to the kneading/granulating equipment 6.

Caking coal having a cohesive strength index of 75% or more, a volatile content of 15 to 35%, and a maximum fluidity of logddpm 2.0 to 4.5 is put into the caking coal hopper 3, and a predetermined amount of the caking coal is finely powdered. It is put in the crusher 4 for powder or the crusher 5 for ultrafine powder. In the pulverizer 4 for fine powder, caking coal is pulverized to a particle size of 70% or more with 0.6 mm or less to obtain fine caking coal. The pulverizer 4 for fine powder is not particularly limited, and one capable of pulverizing to the above particle size can be used. The crushed fine powder caking coal is conveyed to the kneading/granulating equipment 6.

A predetermined amount of inferior coal and fine powder caking coal are put in the kneading/granulating equipment 6, and liquid binder (liquid bituminous material) is dropped or sprayed to the fine powder caking coal and kneaded to prepare a kneaded product. Or, after kneading, granulate with a molding machine to prepare a molded product. The granulation method is not particularly limited.

From the kneading/granulating facility 6, the kneaded product or molded product is conveyed to the blending facility with the coke raw coal, and the blended coal blended in the blending facility is charged into the coke oven and dry distilled to produce blast furnace coke. .. The kneaded product or the molded product may be supplied to the coke raw coal on the belt conveyor without installing the compounding equipment.

Next, necessary and preferable requirements for the production method of the present invention will be described.

(Liquid binder: 8 to 20 mass%)
The liquid binder added when preparing the kneaded product is a liquid bituminous product or the like. Liquid bituminous materials are coal-based binders such as coal tar, petroleum-based binders such as asphalt, and other bituminous binders. Further, the surface moisture of coal has a function of binding coal particles and has a function as a binder. Therefore, when coal has surface moisture, it is included in the addition amount of the liquid binder. The surface water content% of coal is calculated by subtracting the water content% of JIS-M8803 from the total water content of JIS-M8811. Ordinary coal used in steel mills has a moisture content of about 2%.

When the addition amount of the liquid binder is less than 8 mass% with respect to the fine caking coal, the fine caking coal is peeled off from the surface of the poor quality coal. Further, if the amount of the liquid binder added to the fine powder caking coal exceeds 20% by mass, the amount of the binder is excessive and the strength of the kneaded product cannot be maintained.

(Poor coal: less than 0.1 mm is 10% or less, 0.1-5.0 mm is 70% or more)
If less than 0.1 mm of the poor quality coal to be kneaded is blended with more than 10%, the compatibility between the coals deteriorates, a good coke structure cannot be obtained, and the coke strength decreases. If less than 70% of low-grade coal has a coke structure of 0.1 to 5.0 mm, a large crack is formed in the coke structure and the coke strength decreases. By the way, the balance of more than 5.0 mm is 20% or less. Further, in the present invention, the inferior coal has a caking strength index of less than 50%.

(Fine powder caking coal: 0.6% or less 70% or more)
If the fine cohesive coal covering the inferior coal is less than 70% in the amount of 0.6 mm or less, the inferior coal cannot be surrounded well and the compatibility deteriorates, so that a good coke structure cannot be obtained and the coke strength decreases. .. When the cohesion index of the pulverized coking coal is less than 75% or the maximum fluidity is less than logddpm 2.0, the compatibility between coals is deteriorated due to insufficient cohesion and a good coke structure can be obtained. Without coke strength is reduced. The amount of coal having a maximum fluidity logdddpm of 4.5 is small in terms of resources. Further, in the case of a caking coal having a caking strength index of 75% or more and a maximum fluidity of logddpm 2.0 to 4.5, the volatile content is usually 15 to 35%.

(Kneaded product or molded product: 1-40% by mass of inferior coal with respect to coke raw coal)
If the kneaded product or molded product to be mixed with the coke raw coal is less than 1% by mass of the poor coal with respect to the coke raw coal, the effect of using the inexpensive poor coal will not be sufficiently exhibited. Further, if the kneaded product or the molded product is more than 40% by mass of the poor quality coal with respect to the coke raw coal, sufficient coke strength cannot be obtained.

[Other forms]
A method for producing coke by adding a superfine powder caking coal to the poor quality coal, a fine powder caking coal and a liquid binder to obtain a kneaded product or a molded product will be described. This method is to carry out the process indicated by a dotted line in the flow chart of FIG. 1 in which caking coal is crushed to prepare ultrafine caking coal. In the pulverizer 5 for ultrafine powder, caking coal is pulverized to a particle size of 70% or more with 0.06 mm or less to obtain ultrafine powder caking coal. The pulverizer 5 for ultrafine powder is not particularly limited, and one capable of pulverizing to the above particle size can be used. Then, the pulverized ultrafine caking coal is conveyed to the kneading/granulating facility 6, and a predetermined amount of inferior coal, fine caking coal, and ultrafine caking coal are mixed into fine caking coal and ultrafine caking coal. Liquid binder (liquid bituminous material) of 3 to 26 mass% with respect to the total amount of charcoal is dropped or sprayed and kneaded to prepare a kneaded product, or granulated by a molding machine after kneading to create a molded product. To do.
Next, regarding this method, necessary requirements and preferable requirements will be described.

(Ultra fine cohesive coal: 70% or more for 0.06 mm or less)
The particle size of the ultrafine cohesive coal added when preparing the kneaded product is preferably 0.06 mm or less. The reason for this is that if the particle size of the ultrafine cohesive coal is more than 0.2 times the average particle size of the fine cohesive coal, the ability to bond the poor quality coal and the fine cohesive coal by the solid crosslinking force. May be reduced. Therefore, the particle size of the ultra-fine caking coal is preferably 0.2 times or less the average particle size of the fine caking coal. That is, since the particle size of the fine powder caking coal is 0.6 mm or less (for example, the average particle size 0.3 mm), the particle size of the ultrafine powder caking coal is 0. It is preferably 06 mm or less. Further, it is ideal that particles having a diameter of 0.06 mm or less are 100%, but it is difficult to completely grind with an actual grinder, and in addition, a particle diameter larger than 0.06 mm is 30%. It has been confirmed that there is no problem even if it is mixed if it is less than %. However, if less than 0.06 mm is less than 70%, the ability to bond the poor quality coal and the fine cohesive coal by the solid crosslinking force may be reduced.

(Liquid binder: 3 to 26% by mass based on the total amount of fine cohesive coal and ultrafine cohesive coal)
When preparing the kneaded product, in addition to the ultrafine powder caking coal, the addition amount of the liquid binder should be 3 to 26% by mass as an external number with respect to the total amount of the fine powder caking coal and the ultrafine powder caking coal. Added to. When the addition amount of the liquid binder is less than 3% by mass based on the total amount of the fine cohesive coal and the ultrafine cohesive coal, the fine cohesive coal is peeled off from the surface of the poor quality coal. Further, if the addition amount of the liquid binder exceeds 26 mass% with respect to the total amount of the fine powder caking coal and the ultrafine powder caking coal, the liquid binder is excessive and the strength of the kneaded product cannot be maintained.

(Content of ultrafine caking coal: 1 to 10% by mass based on the total of fine caking coal and ultrafine caking coal)
When the content of the ultra-fine cohesive coal added during the preparation of the kneaded product is less than 1% by mass based on the total amount of the fine-cohesive coal and the ultra-fine cohesive coal, there is a gap between the poor-quality coal and the fine-caking coal. In some cases, the effect of bonding by the solid crosslinking force may not be sufficiently exerted. On the other hand, if it is more than 10% by mass, the amount becomes excessive with respect to the voids between the poor quality coal and the fine powder caking coal, and ultrafine powder caking coal that is not kneaded may be generated. Therefore, the content ratio of the ultrafine powder caking coal is preferably 1% by mass or more and 10% by mass or less with respect to the total amount of the fine powder caking coal and the ultrafine powder caking coal.

(Relationship between content of liquid binder and content of ultrafine cohesive coal)
As shown in Examples below, when a kneaded product was prepared in a combination of liquid binders with various contents and ultrafine coking coal, the content Y of liquid binders (mass%) and It has been found that it is preferable to add a liquid binder and ultrafine caking coal so that the content X (mass %) of the fine caking coal satisfies the following formula (1).
(−5/4)×X+8≦Y≦(6/10)×X+20 (1)

FIG. 2 shows the relationship between the content of the liquid binder and the content of the ultrafine powder caking coal. Line A shown in FIG. 2 is Y=(−5/4)×X+8, and line B is Y=(6/10)×X+20. When the content Y (mass %) of the liquid binder is set to the left side or more of the formula (1) with the content X (mass %) of the ultrafine powder caking coal as a variable, when the kneaded product or the molded product is conveyed, It is possible to further improve the property of hardly generating dust (hereinafter referred to as "non-dusting property"), and when it is set to the right side of the formula (1) or less, a conveyor belt or a conveyor can be used when a kneaded product or a molded product is conveyed. It is possible to further improve the property of being hard to adhere to the chute of the connecting portion (hereinafter referred to as “non-adhesiveness”).

[Other]
When the particle size of the kneaded product exceeds 50 mm, the strength may decrease, and when the particle size is less than 8 mm, the bulk density may decrease when mixed with the coke raw coal. Therefore, it is preferable that the kneaded product is kneaded to have a particle size of 8 to 50 mm. Moreover, after forming a kneaded product, it is molded to form a molded product.

Next, examples of the present invention will be described. The conditions in the examples are one condition example adopted for confirming the feasibility and effects of the present invention, and the present invention is based on the one condition example. It is not limited. The present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

Less than 0.1 mm is less than 10%, 0.1-5.0 mm is less than 70% adjusted granularity, cohesion index is 75% or more, volatile matter is 15-35%, maximum fluidity is logddpm 2.0 to 4.5, fine powder caking coal adjusted to a particle size of 70 to 95% for 0.6 mm or less, and ultra fine powder caking adjusted to a particle size of 70% or more for 0.06 mm or less. I prepared charcoal. In the examples and the comparative examples, the inferior coal, the fine cohesive coal and the ultrafine cohesive coal were used. Table 1 shows the particle sizes of the fine cohesive coal and the ultrafine cohesive coal. In Table 1, fine cohesive coal is referred to as "fine powder" and ultrafine cohesive coal is referred to as "ultrafine powder".

As an example, inferior coal, fine cohesive coal and ultrafine cohesive coal, such that the ratio of inferior coal to coking coal (the total of fine cohesive coal and ultrafine cohesive coal) is 1.5 to 4.0. The knots were mixed. A liquid binder (tar) was added to this mixture so as to be 3 to 25.5 mass% with respect to the total of the fine powder caking coal and the ultrafine powder caking coal, and the mixture was kneaded to obtain a kneaded product. .. Then, the kneaded material was blended so that the mass of the inferior coal was 10 to 40% by mass with respect to the coke raw coal, and the coke was produced by dry distillation. Table 1 shows the ratio of inferior coal to coking coal, the amount of liquid binder added, and the blending ratio of the kneaded product to the coke raw coal.

As a comparative example, inferior coal and fine cohesive coal were mixed so that the ratio of inferior coal to coking coal (the total of fine cohesive coal and ultrafine cohesive coal) was 2-3. Then, this mixture was blended so that the mass of inferior coal was 10 to 40 mass% with respect to the coke raw coal, and the carbon was produced by dry distillation. Table 1 shows the ratio of the poor quality coal to the coking coal and the mixing ratio of the kneaded material to the coke raw coal.

With respect to the obtained coke, the cold strength DI and the strength CSR after hot reaction were measured according to the above-described measuring method. Table 2 shows the cold strength DI and the post-hot reaction strength CSR of the coke. In addition, Table 2 shows non-adhesiveness and non-dusting property. Non-adhesion is ◎ when there is no adhesion of the kneaded material to the conveying device, ○ when there is almost no adhesion, x when there is almost no dust generation, and there is no dusting of the kneaded material during transportation. The case is indicated as ⊚, the case where there is almost no is indicated as ○, and the case where there is almost is indicated as ×.

In Examples 1 to 29, peeling of the fine cohesive coal was not observed from the surface of the poor quality coal. On the other hand, in Comparative Examples 1 to 7, peeling of the fine powder caking coal was observed from the surface of the poor quality coal.

The cold strength DI and post-hot reaction strength CSR of Examples 1 to 29 are higher than the cold strength DI and post-hot reaction strength CSR of Comparative Examples 1 to 7. From this, inferior coal and pulverized caking coal, by adding a liquid binder and kneaded to form a kneaded product, it is possible to suppress peeling of the pulverized caking coal from the surface of the inferior coal, and use this kneaded product. It can be seen that the coke having sufficient strength can be obtained by producing the coke.

In addition, in Examples 2, 4, 6, 8, 10, 12, 14 to 29, in which ultrafine powder caking coal was added in addition to inferior coal, fine powder caking coal and liquid binder, the addition amount of the liquid binder was changed. At least, by adding ultrafine cohesive coal, it is possible to suppress the exfoliation of fine cohesive coal from the surface of inferior coal, and even if the amount of liquid binder added is increased, ultrafine cohesive coal is added. By doing so, peeling of the fine powder caking coal from the surface of the poor quality coal can be suppressed. Moreover, the cokes of Examples 2, 4, 6, 8, 10, 12 and 14 were prepared using a kneaded product obtained from inferior coal, fine cohesive coal and a liquid binder without adding ultrafine cohesive coal. The cold strength DI and the post-hot reaction strength CSR are higher than those of the produced cokes of Examples 1, 3, 5, 7, 9, 11, and 13.

In Examples 10, 28 and 29, there was almost no dust generation of the kneaded material during transportation, and the non-dust generation was good (good). In Examples 2, 4, 6, 8, 12, and 14 to 27, the relationship between the content ratio of the liquid binder and the content ratio of the ultrafine coal satisfies the relationship of the above formula (1). The kneaded product did not generate dust during transportation, and the non-dusting property was ⊚ (very good).

In Examples 24 to 27, there was almost no adhesion of the kneaded material to the transfer device, and the non-adhesion was good (good). In Examples 2, 4, 6, 8, 10, 12, 14 to 23, 28 and 29, the relationship between the content rate of the liquid binder and the content rate of the ultrafine coal is the relationship of the above formula (1). Since the content was satisfied, there was no adhesion of the kneaded material to the transfer device, and the non-adhesion was ⊚ (very good).

As described above, by adding the liquid binder to the inferior coal and the pulverized coking coal, it is possible to suppress peeling of the pulverized cohesive coal from the surface of the inferior coal and to obtain coke having sufficient strength.

Furthermore, in addition to inferior coal, fine cohesive coal and liquid binder, by adding ultra-fine cohesive coal, even if the amount of liquid binder added is reduced or increased, from the surface of inferior coal, fine powder Caking coal can be prevented from peeling off, and coke having sufficient strength can be obtained.

ADVANTAGE OF THE INVENTION According to this invention, peeling of the coking coal which improves the compatibility with coke raw material coal can be suppressed from the surface of inferior coal, and also even if cheap inferior coal is mix|blended with caking coal in large quantities. It is possible to produce good quality blast furnace coke. Therefore, the present invention has high industrial applicability.

A Line showing non-dusting boundary B Line showing non-sticking boundary

Claims (3)

The cohesion index is less than 50%, less than 0.1 mm is 10% or less, 0.1-5.0 mm is adjusted to a particle size of 70% or more, and cohesion index is 75% or more, The volatile content is 15 to 35%, the maximum fluidity is logddpm 2.0 to 4.5, and 0.6 mm or less is fine pulverized coking coal adjusted to a particle size of 70% or more, and further 0.06 mm or less is 70. Additionally% or more micronized caking coal which is adjusted to a particle size, the content of the liquid binder is 3 to 26 mass% outside the number of the total of the ultrafine caking coal and the pulverized caking coal As described above, after adding the liquid binder and kneading these, or after kneading and molding, the coke raw coal is adjusted so that the mass of inferior coal to the coke raw coal is 1 to 40% by mass. A method for producing coke for a blast furnace, which comprises blending and carbonizing. The pulverized coke for blast furnace according to claim 1, wherein the ultrafine pulverized coking coal is contained in an amount of 1 to 10% by mass with respect to the total of the pulverized cohesive coal and the ultrafine cohesive coal. Production method. The liquid binder and the ultrafine caking coal so that the content Y (mass%) of the liquid binder and the content X (mass%) of the ultrafine powder caking coal satisfy the following formula (1). The method for producing blast furnace coke according to claim 1 or 2, further comprising:
(−5/4)×X+8≦Y≦(6/10)×X+20 (1)

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