JP2016079388A - Method of producing blast furnace coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing blast furnace coke by using poor-quality coal coated with caking coal, at a transportation step of which or the like, exfoliation of the caking coal, which is used for improving compatibility with raw material coal for coke, from the surface of the poor-quality coal can be suppressed and a ratio of the poor-quality coal to the caking coal for improving compatibility with raw material coal for coke can be made higher.SOLUTION: A method of producing blast furnace coke comprises the steps of: adding a liquid binder to a mixture of the poor-quality coal, the caking index of which is lower than 50% and the granularity of which is adjusted so that particles each having the size smaller than 0.1 mm account for 10% or less and particles each having the size of 0.1-5.0 mm account for 70% or more, with the fine-powder caking coal, the caking index of which is higher than 75%, which has 15-35% volatile matter and maximum fluidity of 2.0-4.5 logddpm, and the granularity of which is adjusted so that particles each having the size smaller than 0.6 mm account for 70% or more, so that the liquid binder becomes 8-20 mass% of the mass of the fine-powder caking coal as an outer number; kneading the liquid binder-mixed mixture or kneading/molding the liquid binder-mixed mixture; blending the kneaded or kneaded/molded liquid binder-mixed mixture in the raw material coal for coke so that a mass ratio of the poor-quality coal to the raw material coal for coke becomes 1-40 mass%; and carbonizing the resulting raw material coal for coke.SELECTED DRAWING: Figure 1

Description

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

  In blast furnace operation, massive iron ore, powdered iron ore or agglomerates of iron dust are efficiently reduced by heating to produce pig iron and generate CO reducing gas and ensure the ventilation of the reducing gas. Coke is charged into the blast furnace as a spacer for this purpose.

  In order for the blast furnace coke to be fully effective as a spacer in the blast furnace, it has sufficient strength not to collapse due to impact during loading into the blast furnace or load loading of the charge in the blast furnace. Required. On the other hand, since high-quality caking coal as a raw material for coke is exhausted in terms of resources, many methods for producing coke having the required strength using inferior quality coal have been proposed.

  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 coal pulverization There is a method of blending by adjusting the particle size, etc., and how well blended with good quality caking coal is being studied.

  In the method of blending by adjusting the pulverization particle size of coal, caking coal is coarsely crushed, and inferior coal with a lot of inert is finely pulverized to improve caking property of raw coal during dry distillation. , Improving coke quality. On the other hand, since the coke strength may decrease when the particle size of the inferior coal is reduced, there is a technique for coarsening the particle size of the inferior coal.

  In this regard, in Patent Document 1, there is a case where sufficient coke strength cannot be obtained only by coarsening the grain size of the inferior coal, and this is because the grain size of the inferior coal is coarsened. It is described that the size of both particles becomes the same, and the contact between the particles becomes point contact, so that the method of compatibility (compatibility) between the poor quality coal and the coke raw material coal becomes insufficient. .

  Therefore, in Patent Document 1, 0.01 mm of 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, which is compatible with coke raw material coal. Less than 30%, 0.01 to 1.0 mm of caking coal whose particle size is adjusted to 50% or more, covering the particle surface of inferior coal, and blending with coke raw coal, A technique for improving the compatibility with coke raw coal and obtaining sufficient coke strength is disclosed.

  However, in the technique disclosed in Patent Document 1, since the poor quality coal and the caking coal that improves the compatibility of the coke raw material coal are only mixed and approached, the surface of the poor quality coal is transferred from the surface of the poor quality coal in the conveying process or the like. As a result, there is a problem that the effect of improving the compatibility with the coke raw material coal cannot be obtained sufficiently.

  Moreover, in patent document 1, although the ratio of inferior quality coal with respect to caking coal which improves compatibility with coke raw material coal is set to 1.0 or 1.5, the ratio of cheap inferior quality coal in coke raw material coal is set. In view of the desire to increase, it is desirable to increase the ratio of inferior 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 inferior coal during the conveyance process or the like, the caking coal is bonded to the inferior coal in consideration of the amount of caking coal to be peeled off. Even if the amount of charcoal is increased, that is, the ratio of inferior coal to caking coal is lowered, it is difficult to increase the ratio of inferior charcoal to caking coal.

JP 07-157769 A

  In view of the current state of the prior art described above, the present invention can suppress the peeling of caking coal that improves compatibility with coke raw coal from the surface of inferior coal in the conveyance process and the like. It aims at providing the manufacturing method of the coke using the inferior coal coat | covered with caking coal which can make the ratio of the inferior coal with respect to caking coal which improves the compatibility of caking coal high.

  The present inventors diligently studied a method for solving the above-described problems. In Patent Document 1, in the method of supplementing a binder such as bituminous material, the bituminous material is not necessarily the same as the coal quality, and a homogeneous coke cannot be obtained. It is described that the inferior coal is coated with caking coal that improves compatibility with the coke raw coal because it has the disadvantage of promoting and adversely affecting the coke strength.

  On the other hand, the inventors added a liquid binder such as bitumen to kneaded coal that improves the compatibility between the inferior coal and the coke raw material coal, and kneaded, from the surface of the inferior coal It has been found that an inferior coal coated with caking coal can be obtained which can suppress peeling of fine caking coal and increase the ratio of the inferior coal to caking coal. Furthermore, it discovered that the coke manufactured using the poor quality coal coat | covered with this caking coal had sufficient intensity | strength.

The present invention has been made based on the above findings, and the gist thereof is as follows.
(1) The cohesive strength index is less than 50%, less than 0.1 mm is less than 10%, 0.1 to 5.0 mm is adjusted to a particle size of 70% or more, and the cohesive strength index is 75. % Volatile content 15-35%, maximum fluidity logddpm 2.0-4.5, 0.6mm or less fine powder caking coal adjusted to a particle size of 70% or more, the fine powder caking coal After adding a liquid binder so that the external number is 8 to 20% by mass and kneading these, or kneading and molding, the coke raw coal is inferior to the coke raw coal. A method for producing coke for a blast furnace, characterized in that it is blended so as to be 1 to 40% by mass and dry-distilled.
(2) To the inferior charcoal and the pulverized caking coal, ultrafine caking coal whose 0.06 mm or less is adjusted to a particle size of 70% or more is added, and the content of the liquid binder is reduced to the pulverized caking coal. And the superfine powdered caking coal is added so that the external number is 3 to 26% by mass. The method for producing coke for blast furnace as described in (1) above.
(3) The ultrafine caking coal contains 1 to 10% by mass of the total amount of the fine caking coal and the ultrafine caking coal, as described in (2) above A method for producing coke for blast furnace.
(4) 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 caking coal satisfy the following formula (1): Caking coal is added, The manufacturing method of the coke for blast furnaces as described in said (2) or (3) characterized by the above-mentioned.
(−5/4) × X + 8 ≦ Y ≦ (6/10) × X + 20 (1)

  According to the present invention, from the surface of the inferior coal, it is possible to suppress peeling of the caking coal that improves compatibility with the coke raw material charcoal. High quality blast furnace coke can be manufactured.

It is a figure which shows the flow which knead | mixes and granulates by adding a liquid binder to inferior quality coal and 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 caking coal.

  Hereinafter, the method for producing coke for blast furnace of the present invention (hereinafter referred to as the production method of the present invention) will be described. In addition, below, the content rate (mass%) of the liquid binder with respect to pulverized caking coal and the content rate (mass%) of the liquid binder with respect to the sum total of pulverized caking coal and ultrafine caking coal The content (mass%) of the ultrafine caking coal with respect to the sum of the fine caking coal and the ultrafine caking coal is indicated by an inner number.

  The present inventors can suppress peeling of caking coal that improves compatibility with coke raw coal (hereinafter referred to as “fine caking coal”) from the surface of inferior charcoal. The production method of inferior coal coated with fine caking coal that can increase the ratio of inferior coal was investigated.

  In Patent Document 1, in the method of supplementing a binder such as bituminous material, the bituminous material is not necessarily the same as the coal quality, and a homogeneous coke cannot be obtained. It is described that the inferior coal is coated with caking coal that improves compatibility with the coke raw coal because it has the disadvantage of promoting and adversely affecting the coke strength.

  Then, even if it adds a liquid binder like bitumen to a mixture of inferior charcoal and pulverized caking coal, the coke strength is considered to decrease. By adding a liquid binder to the charcoal and kneading, it was thought that peeling of the fine caking coal could be suppressed from the surface of the inferior coal.

  Therefore, the following tests were conducted. Less than 0.1 mm is 10%, 0.1 to 5.0 mm is 70%, and over 5.0 mm is inferior coal adjusted to a particle size of 20%, the cohesive strength index is 75% or more, and the volatile content is 15 to 15%. A pulverized caking coal having a maximum fluidity of 35 to 35%, logddpm 2.0 to 4.5, and 0.6 mm or less adjusted to a particle size of 90% was prepared.

  Inferior coal and pulverized caking coal are mixed so that the ratio of inferior coal to pulverized caking coal becomes 2.5, and this mixture is in a liquid state so as to be 14% by mass with respect to pulverized caking coal. A binder (tar) was added and kneaded to obtain a test kneaded product 1. Thereafter, the test kneaded product 1 was blended so that the mass of the inferior coal was 10% by mass with respect to the coke raw material coal, and dry-distilled to produce the test coke 1.

  For comparison, inferior coal 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, a cohesive strength index of 75% or more, volatilization 15% to 35% of minute, maximum fluidity is logddpm 2.0 to 4.5, 0.6mm or less is prepared fine pulverized caking coal adjusted to 90% particle size, The inferior quality coal and fine caking coal were mixed without adding a liquid binder (tar) so that the ratio was 2.5, and a test mixture 1 was obtained. Thereafter, the test mixture 1 was mixed with the same coke raw material coal as described above so that the mass of the inferior coal was 10% by mass, and dry-distilled to produce the test coke 2.

  The test kneaded product 1 and the test mixture 1 were impacted and the peeling of the fine caking coal from the surface of the inferior coal was investigated. The test kneaded material 1 was peeled off from the surface of the inferior coal. Although not observed, pulverized caking coal peeled off from the surface of the poor quality coal in the test mixture 1.

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

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

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

By the way, the upper limit of the ratio of inferior coal to pulverized caking coal is not particularly stipulated, and pulverized caking coal covers the surface of the inferior coal particles, and the effect of improving compatibility with coke raw coal is sufficient. In the range which can be obtained, it is so preferable that it is a high ratio, for example, 4.0 is mentioned.
Moreover, when the ratio of the inferior coal with respect to pulverized caking coal is set, according to this ratio, as described later, the mass of the inferior coal with respect to the coke raw coal is 1 to 40% by mass, so that the coke raw coal is 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 caking coal from the surface of the inferior coal, and the coke strength, the following tests were performed. The test is a test similar to the above, and the inferior coal and pulverized caking coal used in the above test are mixed so that the ratio of the inferior coal to the pulverized caking coal becomes 2.5, and the obtained mixture is mixed. Various addition amounts of liquid binder (tar) were added to and kneaded with pulverized caking coal to obtain a test kneaded product. Then, the test kneaded material was blended so that the mass of the inferior coal was 10% by mass with respect to the coke raw material coal, and 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 peeling of fine caking coal from the surface of inferior coal, and by producing coke using this kneaded product, It was found that coke having sufficient strength could be obtained.

  Moreover, it is preferable that the addition amount of a binder can be freely changed according to the price of inferior coal and a binder. Accordingly, the present inventors can suppress peeling of fine caking coal from the surface of the inferior coal even when the amount of the liquid binder is decreased or increased, and a sufficient coke strength is obtained when dry distillation. The kneaded material to be obtained was examined.

  When the amount of the liquid binder is small with respect to the inferior coal and pulverized caking coal, the cross-linking power between the inferior coal and the pulverized caking coal is weakened. Since coke strength could not be obtained, it was considered to increase the bridging power between coals.

  In addition, when the amount of liquid binder is large with respect to inferior coal and finely caking coal, the kneaded product is softened by the excess liquid binder, and the strength cannot be maintained, and further, the kneaded product is in contact with the excess liquid binder. Since the strength due to the sticking of the ink cannot be maintained, it was considered to adsorb or absorb an excessive liquid binder.

  When the present inventors investigated the means for that, it invented adding in addition to a liquid binder to an inferior quality coal and pulverized caking coal, and also adding ultrafine caking coal. That is, when the amount of the liquid binder is small, it is considered that the ultrafine coal powder fills the gap between the inferior coal and the fine coal powder, and bonds the coal particles by the solid crosslinking force. In addition, when the amount of liquid binder is large, the ultrafine caking coal adsorbs or absorbs a 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 I wouldn't let it go.

  Therefore, the following tests were conducted. Less than 0.1 mm is 10%, 0.1 to 5.0 mm is 70%, and over 5.0 mm is inferior coal adjusted to a particle size of 20%, the cohesive strength index is 75% or more, and the volatile content is 15 to 15%. A pulverized caking coal having a maximum fluidity of 35 to 35%, logddpm 2.0 to 4.5, and 0.6 mm or less adjusted to a particle size of 90% was prepared.

  First, in the case where the amount of the liquid binder is small, the inferior coal and the pulverized caking coal are mixed so that the ratio of the inferior coal to the pulverized caking coal becomes 2.5, and 0.06 mm or less is 70%. The ultrafine caking coal adjusted to a particle size of 5% by mass was mixed with respect to the total of the fine caking coal and the ultrafine caking coal. To this mixture, a liquid binder (tar) was added and kneaded so as to be 5% by mass with respect to the total of finely powdered caking coal and ultrafine caking coal, and test kneaded material 2 was obtained. Then, the test coke 3 was manufactured by blending the test kneaded material so that the mass of the inferior coal was 10% by mass with respect to the same coke raw material coal as described above, and dry-distilling.

  Next, in the case where the amount of the liquid binder is large, the pulverized caking coal and the inferior coal used in the production of the test coke 3 are set so that the ratio of the inferior coal to the pulverized caking coal becomes 2.5. Is mixed with pulverized caking coal, and 0.06 mm or less is adjusted to a particle size of 70%, and 5% by mass with respect to the total of pulverized caking coal and ultrafine caking coal. It mixed so that it might become. To this mixture, a liquid binder (tar) was added and kneaded so as to be 24% by mass with respect to the total of finely powdered and ultrafinely powdered coal, and test kneaded material 3 was obtained. Thereafter, the test coke 4 was produced by blending the test kneaded material so that the mass of the inferior coal was 10% by mass with respect to the same coke raw material coal as described above, and dry-distilling.

  As a reference object, a test obtained by adding a liquid binder (tar) to 14% by mass to the above-mentioned finely powdered caking coal and inferior coal, and kneading without adding ultrafine caking coal. The test coke 1 produced by blending the test kneaded product 1 with the kneaded product 1 and coke raw coal and dry-distilling was used.

  When the test kneaded material 2 and the test kneaded material 3 were impacted and the peeling of the fine caking coal from the surface of the inferior coal was investigated, the test kneaded material 2 and the test kneaded material 3 were separated from the surface of the inferior coal. No peeling of caking coal was observed.

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

  From this, when adding a liquid binder to inferior coal and pulverized caking coal and kneading to obtain a kneaded product, by adding ultrafine caking coal, even if the amount of liquid binder is reduced, The fine caking coal fills the gap between the inferior quality coal and the fine caking coal, and the coal particles are bonded by the solid crosslinking force, so the peeling of the fine caking coal can be suppressed from the surface of the inferior coal, Even if the amount of the liquid binder is increased, the ultrafine caking coal adsorbs or absorbs a part of the liquid binder and does not allow excessive liquid binder to ooze out on the surface of the kneaded product. Peeling of fine caking coal can be suppressed from the surface. And the intensity | strength of the coke manufactured using this kneaded material acquired the knowledge that it became comparable or more compared with the coke manufactured using the kneaded material created without adding superfine caking coal. .

  In addition, in order to investigate the relationship between the amount of liquid binder added and the amount of cohesive coal peeled from the surface of inferior coal when the content of ultrafine coking coal was changed, and the coke strength. The following tests were conducted.

  The test is the same test as above, and the inferior coal and pulverized caking coal used in the above test were mixed so that the ratio of the inferior coal to the pulverized caking coal was 2.5, The coal is mixed so as to have various contents with respect to the sum of the finely powdered and ultrafinely caking coal, and the resulting mixture is mixed with the sum of the finely powdered and ultrafinely caking coal. Various addition amounts of liquid binder (tar) were added and kneaded to obtain a test kneaded product. Then, the test kneaded material was blended so that the mass of the inferior coal was 10% by mass with respect to the coke raw material coal, and dry-distilled to produce a test coke.

  As a result of the test, the amount of addition of the liquid binder is 3 to 26 masses based on the total amount of the fine powder caking coal and the ultra fine caking coal by adding the super fine caking coal to the inferior coal and the fine caking coal. %, It was found that the coke having sufficient strength can be obtained from the surface of the inferior coal by suppressing the peeling of the fine caking coal.

  Moreover, even if the amount of liquid binder is reduced by adding 1 to 10% by mass of ultrafine caking coal to the total of fine caking coal and ultrafine caking coal, It was found that coking coal can be prevented from peeling and coke having sufficient strength can be obtained.

The results of the study are summarized as follows.
A liquid binder is added to the inferior coal and pulverized caking coal so as to be 8 to 20% by mass with respect to the pulverized caking coal, kneaded, blended with coke raw coal, and dry-distilled to produce coke. In addition, it is possible to suppress the peeling of the fine caking coal from the surface of the inferior coal, and furthermore, adding the ultra fine caking coal to the inferior charcoal and the fine caking coal to make the total of the fine caking coal and the ultra fine caking coal. On the other hand, by adding and kneading the liquid binder so as to be 3 to 26% by mass, peeling of the fine caking coal can be suppressed from the surface of the inferior coal. And the coke which has sufficient intensity | strength can be obtained by mix | blending the obtained kneaded material with coke raw material charcoal, and carrying out dry distillation and manufacturing coke.

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

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

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

  A caking coal with a caking 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 caking coal is pulverized. Into the pulverizer 4 for grinding or the pulverizer 5 for ultrafine powder. In the pulverizer for fine powder 4, the caking coal is pulverized to a particle size of 0.6% or less to 70% or more to obtain fine powder caking coal. The pulverizer for fine powder 4 is not particularly limited, and those capable of being pulverized to the above particle size can be used. The pulverized caking coal is conveyed to the kneading and granulating equipment 6.

  Predetermined amounts of inferior coal and pulverized caking coal are put into the kneading and granulating equipment 6, and a liquid binder (liquid bitumen) is dropped or sprayed on the pulverized caking coal to create a kneaded product. Alternatively, the mixture is granulated with a molding machine after kneading to create a molded product. The granulation method is not particularly limited.

  The kneaded product or molded product is transported from the kneading / granulating facility 6 to a blending facility with coke raw coal, and the blended coal blended in the blending facility is charged into a coke oven and dry-distilled to produce blast furnace coke. . In addition, you may supply a kneaded material or a molding to coke raw coal on a belt conveyor, without installing a mixing equipment.

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

(Liquid binder: 8-20% by mass)
The liquid binder added at the time of preparing the kneaded product is a liquid bitumen. Liquid bitumen is coal-based binders such as coal tar, petroleum-based binders such as asphalt, and other bituminous binders. Moreover, since the surface water | moisture content of coal has the function to couple | bond coal particles and has a function as a binder, when coal has surface water | moisture content, it is included in the addition amount of a liquid binder. In addition, the surface moisture% of coal is calculated by subtracting the embraced moisture% of JIS-M8803 from the total moisture% of JIS-M8811. Ordinary coal handled at steelworks has a moisture content of around 2%.

  When the addition amount of the liquid binder is less than 8% by mass with respect to the pulverized caking coal, the pulverized caking coal is peeled off from the surface of the inferior quality coal. Moreover, when the addition amount of a liquid binder exceeds 20 mass% with respect to pulverized caking coal, a binder will be excess and it will become impossible to maintain the intensity | strength of a kneaded material.

(Inferior charcoal: less than 0.1 mm is 10% or less, 0.1 to 5.0 mm is 70% or more)
If the inferior coal to be kneaded is blended with more than 10% of less than 0.1 mm, the compatibility between the coals is deteriorated, and a high-quality coke structure cannot be obtained and the coke strength is lowered. Moreover, when the quality of the inferior coal is 0.1 to 5.0 mm and less than 70%, a large crack is formed in the coke structure, and the coke strength is lowered. Incidentally, the balance exceeding 5.0 mm is 20% or less. In addition, in the present invention, inferior coal is intended for those having a cohesive strength index of less than 50%.

(Fine powdered coal: 0.6mm or less is 70% or more)
Fine powder caking coal covering inferior charcoal is less than 70% if it is less than 0.6 mm, poor quality charcoal is not surrounded well, compatibility is deteriorated, good quality coke structure is not obtained, and coke strength is reduced. . Further, if the cohesive strength index of finely ground caking coal is less than 75% or the maximum fluidity is less than logddpm 2.0, the compatibility between the coals deteriorates due to insufficient caking, and a high quality coke structure is obtained. The coke strength decreases. Coal exceeding the maximum fluidity logddpm 4.5 is small in terms of resources. Moreover, if the caking strength index is 75% or more and the caking coal has a maximum fluidity of logddpm 2.0 to 4.5, the volatile content is usually 15 to 35%.

(Kneaded product or molded product: 1 to 40% by mass of inferior coal with respect to coke raw material coal)
If the kneaded product or molded product blended with the coke raw coal is less than 1% by mass of the inferior coal relative to the coke raw coal, the effect of using the inexpensive inferior coal is not sufficiently exhibited. Further, when the kneaded product or the molded product exceeds 40% by mass of the inferior coal with respect to the coke raw material coal, sufficient coke strength cannot be obtained.

[Other forms]
A method for producing coke by adding ultra-fine caking coal to inferior charcoal, fine caking coal and liquid binder to obtain a kneaded product or a molded product will be described. This method implements the process shown with the dotted line which grinds caking coal and adjusts ultrafine caking coal in the flowchart of FIG. In the pulverizer 5 for ultrafine powder, the caking coal is pulverized to a particle size of 0.06 mm or less to 70% or more to obtain ultrafine caking coal. The pulverizer 5 for ultrafine powder is not particularly limited, and a pulverizer having the above particle size can be used. Then, the pulverized ultrafine caking coal is transported to the kneading and granulating equipment 6, and a predetermined amount of inferior coal, fine caking coal, and ultrafine caking coal are added to the fine caking coal and ultrafine caking coal. 3 to 26% by mass of liquid binder (liquid bitumen) is dripped or sprayed with respect to the total amount of charcoal, kneaded to create a kneaded product, or granulated with 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 caking coal: 0.06mm or less is 70% or more)
The particle size of the ultrafine caking coal added at the time of preparing the kneaded product is preferably 0.06 mm or less. The reason is that, when the particle size of the ultrafine caking coal is more than 0.2 times the average particle size of the fine caking coal, the ability to bind the poor quality coal and the fine caking coal by solid crosslinking force May be reduced. Therefore, the particle size of the ultrafine caking coal is preferably 0.2 times or less the average particle size of the fine caking coal. That is, the particle size of the finely powdered caking coal is 0.6 mm or less (for example, the average particle size is 0.3 mm), and therefore the particle size of the ultrafine caking coal is 0.3 mm × 0.2. 06 mm or less is preferable. Ideally, 0.06 mm or less is 100%. In addition to being difficult to completely grind with an actual grinder, a particle size larger than 0.06 mm is 30. % Or less, it is confirmed that there is no problem even if it is mixed. However, if the amount of 0.06 mm or less is less than 70%, the ability to bond the inferior coal and pulverized caking coal with solid cross-linking force may be reduced.

(Liquid binder: 3 to 26% by mass with respect to the total of finely powdered caking coal and ultrafine caking coal)
When creating a kneaded product, in addition to the ultrafine caking coal, the addition amount of the liquid binder is 3 to 26% by mass based on the total of the fine caking coal and the ultrafine caking coal. Add to. When the addition amount of the liquid binder is less than 3% by mass with respect to the total of finely powdered caking coal and ultrafine caking coal, the finely caking coal is peeled off from the surface of the inferior coal. Moreover, when the addition amount of a liquid binder exceeds 26 mass% with respect to the sum total of fine powder caking coal and super fine caking coal, the liquid binder will be excessive and it will become impossible to maintain the intensity | strength of a kneaded material.

(Content of ultrafine caking coal: 1 to 10% by mass with respect to the total of fine caking coal and ultrafine caking coal)
When the content of the ultrafine caking coal added at the time of preparing the kneaded material is less than 1% by mass with respect to the total of the fine caking coal and the ultrafine caking coal, there is a gap between the inferior coal and the fine caking coal. May not be sufficiently exerted by the solid crosslinking force. Moreover, when it is more than 10 mass%, it becomes an excessive quantity with respect to the space | gap between inferior quality coal and pulverized caking coal, and the ultra-fine caking coal which is not knead | mixed may generate | occur | produce. Therefore, the content of the ultrafine caking coal is preferably 1% by mass or more and 10% by mass or less with respect to the total of the fine caking coal and the ultrafine caking coal.

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

  In FIG. 2, the relationship between the content rate of a liquid binder and the content rate of an ultrafine caking coal is shown. The line A shown in FIG. 2 is Y = (− 5/4) × X + 8, and the line B is Y = (6/10) × X + 20. When the content X (mass%) of the ultrafine caking coal is a variable, and the content Y (mass%) of the liquid binder is greater than or equal to the left side of the formula (1), when the kneaded product or molded product is conveyed, The property of preventing dust generation (hereinafter referred to as “non-dust generation”) can be further improved, and if it is equal to or less than the right side of the formula (1), a conveyor belt or a conveyor can be used when conveying a kneaded product or a molded product. It is possible to further improve the property of being difficult to adhere to the chute of the connecting portion (hereinafter referred to as “non-adhesive”).

[Others]
When the particle diameter exceeds 50 mm, the strength of the kneaded product may decrease, and when the particle diameter is less than 8 mm, the bulk density may decrease when mixed with coke raw coal. Therefore, the kneaded product is preferably kneaded in a particle size range of 8 to 50 mm. Moreover, after creating a kneaded product, it is molded to produce a molded product.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on these one example conditions. It is not limited. The present invention can adopt 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 10% or less, 0.1 to 5.0 mm is inferior coal adjusted to a particle size of 70% or more, caking strength index is 75% or more, volatile content is 15 to 35%, and maximum fluidity is log ddpm 2.0 to 4.5, 0.6 mm or less fine powder caking coal adjusted to a particle size of 70 to 95%, and 0.06 mm or less fine powder caking adjusted to a particle size of 70% or more Prepared charcoal. In the examples and comparative examples, this inferior coal, pulverized caking coal, and ultrafine caking coal were used. Table 1 shows the particle sizes of the finely powdered caking coal and the ultrafine caking coal. In Table 1, pulverized caking coal is referred to as “fine powder”, and ultrafine caking coal is referred to as “ultra fine”.

  As an Example, inferior charcoal, pulverized caking coal, and ultrafine caustic so that the ratio of inferior charcoal to caking coal (total of pulverized caking coal and ultrafine caking coal) becomes 1.5-4.0. The knot was mixed. A liquid binder (tar) was added to this mixture so as to be 3 to 25.5% by mass with respect to the total of finely powdered and ultrafinely powdered coal, and kneaded to obtain a kneaded product. . Thereafter, 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 material coal, and dry-distilled to produce coke. Table 1 shows the ratio of inferior coal to caking coal, the amount of liquid binder added, and the blending ratio of the kneaded product to coke raw material coal.

  As a comparative example, inferior coal and pulverized caking coal were mixed so that the ratio of inferior coal to caking coal (total of pulverized caking coal and ultrafine caking coal) was 2-3. Thereafter, this mixture was blended with the coke raw material coal so that the mass of the inferior coal was 10 to 40% by mass, and dry-distilled to produce coke. In Table 1, the ratio of the inferior coal with respect to caking coal, and the mixture ratio of the kneaded material to coke raw material coal are shown.

  About the obtained coke, according to the above-mentioned measuring method, cold strength DI and hot post-reaction strength CSR were measured. Table 2 shows the cold strength DI of the coke and the strength CSR after the hot reaction. Table 2 shows non-adhesiveness and non-dusting properties. Non-adhesiveness means ◎ when there is no adhesion of the kneaded product to the transport device, ○ when there is almost no, x when there is no dust, and non-dusting property, there is no dust generation of the kneaded product during transport Cases are indicated as ◎, almost no cases are indicated as ○, and cases are indicated as ×.

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

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

  In addition, in Examples 2, 4, 6, 8, 10, 12, 14 to 29 in which ultrafine powdered coal was added in addition to inferior coal, fine powdered coal and liquid binder, the amount of liquid binder added was Even if it is less, by adding ultrafine caking coal, peeling of fine caking coal can be suppressed from the surface of inferior coal, and adding ultrafine caking coal even if the amount of liquid binder is increased By doing so, peeling of the fine caking coal can be suppressed from the surface of the poor quality coal. In addition, the coke of Examples 2, 4, 6, 8, 10, 12, and 14 does not add ultrafine caking coal, and uses a kneaded material obtained from inferior charcoal, fine caking coal, and a liquid binder. The cold strength DI and the hot reaction strength CSR are higher than the cokes of Examples 1, 3, 5, 7, 9, 11, and 13 produced.

  In Examples 10, 28, and 29, there was almost no dust generation of the kneaded material during conveyance, and the non-dust generation property was good (good). In Examples 2, 4, 6, 8, 12, 14 to 27, since the relationship between the content of the liquid binder and the content of the ultrafine coal satisfies the relationship of the above-described formula (1), There was no dust generation of the kneaded material at the time of conveyance, and the non-dust generation was ◎ (very good).

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

  As described above, by adding a liquid binder to the inferior coal and pulverized caking coal, peeling of the pulverized caking coal can be suppressed from the surface of the inferior coal, and coke having sufficient strength can be obtained.

  Furthermore, in addition to inferior charcoal, pulverized caking coal and liquid binder, by adding ultrafine caking coal, the amount of liquid binder can be reduced or increased from the surface of the inferior charcoal. Peeling of caking coal can be suppressed and coke having sufficient strength can be obtained.

  According to the present invention, from the surface of the inferior coal, it is possible to suppress peeling of the caking coal that improves compatibility with the coke raw material charcoal. High quality blast furnace coke can be manufactured. Therefore, the present invention has high industrial applicability.

A Line indicating non-dusting boundary B Line indicating non-adhesive boundary

Claims (4)

  The cohesive strength index is less than 50%, less than 0.1 mm is less than 10%, 0.1 to 5.0 mm is adjusted to a grain size of 70% or more, and the cohesive strength index is 75% or more, The volatile matter is 15 to 35%, the maximum fluidity is logddpm 2.0 to 4.5, and 0.6 mm or less is adjusted to a particle size of 70% or more. After the liquid binder is added so that the external number is 8 to 20% by mass and these are kneaded, or after kneading and molding, the coke raw coal is in the mass of inferior coal to the coke raw coal. A method for producing coke for blast furnace, which is blended so as to be 1 to 40% by mass and dry-distilled.   To the inferior charcoal and the pulverized caking coal, an ultrafine caking coal whose 0.06 mm or less is adjusted to a particle size of 70% or more is further added, and the content of the liquid binder is reduced to the pulverized caking coal and the ultracoking coal. The method for producing coke for a blast furnace according to claim 1, wherein the addition is performed so that the external number is 3 to 26% by mass with respect to the total of finely powdered caking coal.   3. The blast furnace coke according to claim 2, wherein the ultrafine caking coal is contained in an amount of 1 to 10% by mass with respect to the total of the fine caking coal and the ultrafine caking 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 caking coal satisfy the following formula (1): The method for producing coke for a blast furnace according to claim 2 or 3, wherein
(−5/4) × X + 8 ≦ Y ≦ (6/10) × X + 20 (1)

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