Ferro-coke manufacturing method

Abstract

To provide a production method for ferrocoke that can eliminate deterioration of air permeability in a vertical carbonization furnace to obtain the ferrocoke with stable quality.SOLUTION: A production method for ferrocoke in which the ferrocoke is obtained by continuously carbonizing a molded product containing a carbon-containing substance and an iron-containing substance as raw materials in a vertical carbonization furnace comprises: switching charging of the molded product from a furnace top during normal operation when a temperature deviation occurs in a horizontal direction within the vertical carbonization furnace; charging the ferrocoke, preferably having a drum strength (DI (150 / 15)) of 76 or more from the furnace top; cutting the ferrocoke out from a furnace bottom part; and circulating the ferrocoke from the furnace top to the furnace bottom part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing ferro-coke, in which briquettes containing a carbon-containing substance and an iron-containing substance are carbonized in a vertical carbonization furnace to obtain ferro-coke. [Background technology]

[0002] In the field of steelmaking, the raw material iron ore is charged into a blast furnace together with coke, and the two are reacted at high temperatures to produce pig iron. Coke is obtained by carbonizing coal, and in the blast furnace, it functions as a spacer to improve ventilation, a heat source, and a reducing agent. In recent years, it has been proposed to replace part of the coke charged into the blast furnace with ferro-coke in order to increase the efficiency of the steelmaking process in the blast furnace.

[0003] Ferro-coke is produced by compressing and molding iron-containing materials such as powdered iron ore and carbon-containing materials such as powdered coal, and then carbonizing the compressed material. It contains fine particles of metallic iron produced by the reduction of the iron-containing materials. This metallic iron has a catalytic function that promotes the reaction in which CO2 produced during the reaction in the blast furnace reacts with coke (C) to regenerate the reducing gas CO. Therefore, by using ferro-coke, the gasification reaction of the coke can be started at a low temperature in the blast furnace, and the temperature of the thermal reserve zone can be lowered. Therefore, the use of ferro-coke is expected to contribute to energy conservation and reduction of CO2 emissions, as it greatly reduces the reducing agent ratio. Due to such usefulness, research on the manufacturing technology of ferro-coke is being conducted.

[0004] The general metallurgical coke currently in use is produced by carbonizing the raw material coal in a chamber-hearth coke oven. Therefore, methods of producing ferro-coke using a chamber-hearth coke oven have been investigated. For example, (a) a method of charging a mixture of coal and fine iron ore into a chamber-hearth coke oven and carbonizing it, and (b) a method of cold briquetting coal and iron ore, charging the resulting briquette into a chamber-hearth coke oven and carbonizing it have been proposed (Non-Patent Document 1).

[0005] However, since a normal chamber-type coke oven is made of silica bricks, when iron ore is charged and carbonized, silica, which is the main component of the silica bricks, reacts with the iron ore to produce fayalite, which has a low melting point. Since damage to the silica bricks due to this reaction is a problem, the production of ferro-coke using a conventional chamber-type coke oven has not been industrially carried out. Therefore, a method using a vertical carbonization furnace has been proposed as a ferro-coke production method to replace the chamber-type coke production method (Patent Documents 1 and 2). In these methods, a vertical shaft furnace made of chamotte bricks instead of silica bricks is used as the vertical carbonization furnace. In addition, the raw materials, coal and iron ore, are mixed with a binder and molded into a predetermined size in the cold to obtain molded coal, which is then charged into the vertical carbonization furnace. Then, a heat transfer gas is blown into the vertical carbonization furnace from a tuyere to heat the molded coal, thereby producing molded ferro-coke. According to this method, carbonization can be carried out without damage to the bricks caused by the iron ore. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4666114 [Patent Document 2] Patent No. 5504731 [Patent Document 3] JP 2017-137373 A [Patent Document 4] JP 2014-169348 A [Non-patent literature]

[0007] [Non-Patent Document 1] "Coke Technology Annual Report", Fuel Association, 1958, p.38 Summary of the Invention [Problem to be solved by the invention]

[0008] However, when ferro-coke is produced by the above-mentioned method using a vertical carbonization furnace, there is a problem that the degree of carbonization of the obtained ferro-coke varies. This is because the temperature deviation occurs in the vertical carbonization furnace due to the uneven gas flow in the furnace, and the carbonization efficiency of the molded products is partially reduced. Causes of the uneven gas flow in the furnace include blockage of the gas flow path by molded products flowing into the tuyere and deterioration of gas permeability due to powder brought into the furnace, and measures have been taken for each of them. That is, a method of preventing the flow of molded products into the tuyere by devising a tuyere structure to prevent blockage of the gas flow path (Patent Document 3), and a method of sieving the molded products before charging to reduce the amount of powder brought in (Patent Document 4) have been taken to prevent deterioration of gas permeability. However, the method of Patent Document 4 alone is insufficient for preventing deterioration of gas permeability because it cannot prevent powder generation during the transportation process after sieving or in the furnace.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to propose a method for producing ferro-coke for obtaining ferro-coke of stable quality. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention provides a method for producing ferro coke, which involves continuously carbonizing molded materials containing a carbon-containing substance and an iron-containing substance as a raw material in a vertical carbonization furnace to obtain ferro coke, and is characterized in that, when a temperature deviation occurs in the horizontal direction inside the vertical carbonization furnace, the molded materials are switched to ferro coke, and the ferro coke is charged from the top of the furnace and cut out from the bottom of the furnace, thereby circulating the ferro coke from the top to the bottom of the furnace.

[0011] In the method for producing ferro-coke according to the present invention configured as described above, (1) The amount of ferro coke charged from the top of the furnace is set to 0.5W to W with respect to the amount of ferro coke in the furnace during normal operation (W (tons)). (2) When the difference between the maximum and minimum temperatures measured on multiple thermometers installed horizontally within 5 m above the top of the furnace reaches 50°C or more, the molding material to be charged from the top of the furnace is switched to ferro-coke. (3) The drum strength (DI(150 / 15)) of the ferro-coke is 76 or more. This is believed to be a more preferable solution. Here, "drum strength (DI (150 / 15))" refers to the drum strength: DI (150 / 15) specified in JIS K2151. Effect of the Invention

[0012] According to the method for producing ferro-coke of the present invention, the original charge is switched to briquettes containing a carbon-containing material and an iron-containing material, and ferro-coke is charged from the top of the furnace and cut out from the bottom of the furnace. This allows the ferro-coke to be circulated from the top to the bottom of the furnace, and the powder adhering to the inside of the vertical carbonization furnace, which causes the horizontal temperature deviation, can be discharged outside the furnace. Therefore, by operating normally thereafter, the temperature deviation of the briquettes in the vertical carbonization furnace can be eliminated, and ferro-coke with stable quality (≒ strength of ferro-coke) can be produced. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram for explaining an example of an equipment configuration of the present invention. [Diagram 2] FIG. 2 is a schematic diagram for explaining an example of a main part of the equipment configuration of the present invention. [Diagram 3]1A and 1B are graphs showing the transition of furnace body temperature and the transition of ferro-coke strength, respectively, in the case where the countermeasure of the present invention is not applied. [Figure 4] 1A and 1B are graphs showing the transition of furnace body temperature and the transition of ferro-coke strength, respectively, when the countermeasure of the present invention is implemented. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the embodiments of the present invention will be described in detail. Note that the following embodiments are merely examples of devices and methods for embodying the technical ideas of the present invention, and are not intended to limit the configuration to those described below. In other words, the technical ideas of the present invention can be modified in various ways within the technical scope described in the claims.

[0015] <Regarding normal operation of the method for producing ferro-coke according to the present invention> An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a ferro-coke carbonization facility in this embodiment. As shown in FIG. 1, the ferro-coke carbonization facility in this embodiment mainly includes a storage hopper 1, a sieve 2, a charging device 3, a vertical carbonization furnace 4, and a discharge device 5. As shown in FIG. 2, a total of 32 thermometers 6 to 9 are installed on the vertical carbonization furnace 4 in the height direction and the furnace width direction, and the furnace body temperature is constantly measured. The positions of the thermometers are arranged at intervals of a=4500 mm, b=2150 mm, c=4550 mm, d=5100 mm, and e=590 mm. The horizontal thermometer arrangement interval f was 1770 mm.

[0016] Usually, the briquettes are stored in a storage hopper 1, and the briquettes are cut out from the storage hopper 1 through a sieve 2, and then charged into a vertical carbonization furnace 4 by a charging device 3. The charged briquettes are carbonized by hot air blown into the vertical carbonization furnace 4. Meanwhile, in the lower part of the vertical carbonization furnace 4, the ferro-coke after carbonization is cut out at a constant speed by a discharge device 5. Therefore, by making the charging speed of the briquettes into the vertical carbonization furnace 4 constant, the amount of the briquettes in the furnace does not change, and the briquettes gradually move down in the vertical carbonization furnace 4 while being carbonized. The discharge speed of the discharge device is variable, and in order to avoid poor carbonization and over-carbonization, it is preferable to set the amount of cut out per hour to W / X (ton / hr) with respect to the amount of briquettes in the furnace. Here, the range of X is usually 8≦X≦40.

[0017] <Regarding the method for producing ferro-coke according to the present invention> In the method for producing ferro-coke according to the present invention, as in the above-mentioned operating method, briquettes containing a carbon-containing material and an iron-containing material as a raw material are continuously carbonized in a vertical carbonization furnace to obtain ferro-coke. This ferro-coke production method is characterized in that, when a temperature deviation occurs in the horizontal direction inside the vertical carbonization furnace, the briquettes are switched to ferro-coke, which is charged from the top of the furnace and cut out from the bottom of the furnace, thereby circulating the ferro-coke from the top to the bottom of the furnace.

[0018] Normally, the design concept of a vertical carbonization furnace is to heat the furnace walls at the same height so that the temperatures are equal. Therefore, if a temperature deviation occurs in the horizontal direction, this is suspected to be due to equipment problems such as burners or a deterioration in the permeability of the furnace. In the present invention, the powder adhering to the inside of the vertical carbonization furnace, which is the cause of the horizontal temperature deviation, can be discharged to the outside of the furnace by circulating the ferro-coke from the top to the bottom of the furnace. As a result, the deterioration in permeability during subsequent normal operations can be eliminated.

[0019] Here, the "horizontal temperature deviation in the vertical carbonization furnace" may be calculated in real time during normal operation by calculating the horizontal temperatures of all four thermometers 6-9 installed horizontally on the front and back sides of the vertical carbonization furnace 4 in FIG. 2, and using the deviations. However, in practice, it is preferable to calculate the horizontal temperatures using the top four thermometers 6 as representatives and use the deviation between the maximum and minimum values. In the vertical carbonization furnace 4 shown in FIG. 2, the upper thermometer 6 is preferably installed at a height of 5 m or less from the top of the furnace. This is because the upper part of the vertical carbonization furnace 4 is more susceptible to adhesion of powder, which causes a horizontal temperature deviation, than other parts. In addition, due to the nature of the vertical carbonization furnace 4 in which materials flow from top to bottom in the furnace, there is also the effect of reducing the total amount of powder present in the furnace by detecting an increase in the powder rate with the upper thermometer and taking prompt action.

[0020] In addition, the ferro coke produced according to the method for producing ferro coke of the present invention can be used as the "ferro coke" to be charged in place of the briquettes used during normal operation when a temperature deviation occurs in the horizontal direction. Even if the present invention is achieved by charging ferro coke in place of the briquettes used during normal operation by using ferro coke as a product, the ferro coke circulated in the vertical carbonization furnace is cut out from the bottom together with the powder that causes the horizontal temperature deviation. Therefore, if only the powder that causes the horizontal temperature deviation is removed, the ferro coke can be used as it is as a product. The above steps can be performed while maintaining normal operation without stopping it.

[0021] It is preferable to use the ferro-coke having a drum strength (DI (150 / 15)) of 76 or more as specified by JIS K2151. The drum strength (DI (150 / 15)) of ferro-coke normally produced in a vertical carbonization furnace is 60 to 85. Among them, the drum strength (DI (150 / 15)) of ferro-coke used as a product is 76 or more, so that the ferro-coke circulated according to the present invention can be used as a product as it is.

[0022] In addition, regarding the amount of ferro-coke used to discharge the powder adhering to the inside of the vertical carbonization furnace to the outside of the furnace, when the amount of ferro-coke discharged per hour is W / X (ton / hr) relative to the amount of ferro-coke in the furnace W (ton), it is preferable to continue the operation of controlling the amount of ferro-coke charged from the furnace top per hour (W1) and the amount of ferro-coke discharged from the lower part of the furnace (W2) to be equal for 0.5X to X (hr). In other words, it is preferable to set the amount of ferro-coke used to 0.5W to W relative to the amount of ferro-coke in the furnace W (ton) in normal operation. If the amount of ferro-coke used is 0.5W to W relative to the amount of ferro-coke in the furnace W (ton) in normal operation, the effect of discharging the powder adhering to the inside of the vertical carbonization furnace to the outside of the furnace of the present invention can be sufficiently achieved. EXAMPLES

[0023] <Comparative Example> A comparative example based on the conventional technology will be described with reference to Figs. 3(a) and (b). Fig. 3(a) shows the furnace body temperature when the amount of molded products in the furnace and the amount of cut per hour are 130 / 30 (ton / hr) and the countermeasure according to the present invention is not taken. As a representative of the furnace body temperature, the transition of the thermometers 6 at four points on the first row from the top on the surface side of the furnace body shown in Fig. 2 is shown. As shown in Fig. 3(a), the difference in the furnace body temperature began to widen from February 7, and the temperature difference between the hottest place (unit 1) and the coldest place (unit 3) widened to a maximum of about 200°C. As for the strength of the obtained ferro-coke, as shown in Fig. 3(b), the drum strength (DI(150 / 15)), which is the strength index of ferro-coke, also began to decrease after February 7, when the difference in the furnace body temperature began to widen, and the average drum strength (DI(150 / 15)) during this period was 49.

[0024] <Example of the present invention> An example of the present invention based on the technology of the present invention will be described with reference to Figs. 4(a) and (b). Fig. 4(a) shows the furnace body temperature when the amount of material in the furnace and the amount of material cut per hour are 130 / 30 (ton / hr) and the countermeasure according to the present invention is taken. As shown in Fig. 4(a), the difference in the furnace body temperature started to widen from May 9, and when the difference between the maximum and minimum temperatures became 50°C or more, the charging material was switched to ferro-coke, and the charging of ferro-coke and the discharge of the powder and ferro-coke in the furnace were continued for 30 hours. In this case, the charging amount of ferro-coke from the top of the furnace was 130 (tons) compared to the amount of ferro-coke in the furnace in normal operation, 130 (tons). In addition, the difference in the furnace body temperature started to widen from May 11, and when the difference between the maximum and minimum temperatures became 50°C or more, the charging material was switched to ferro-coke, and the charging of ferro-coke and the discharge of the powder and ferro-coke in the furnace were continued for 25 hours. In this case, the amount of ferro-coke charged from the top of the furnace was 108 tons, compared with 130 tons in the furnace during normal operation.

[0025] As a result, the spread of the temperature difference between the hottest place (unit 1) and the coldest place (unit 2) could be suppressed to a maximum of about 80° C. As shown in Fig. 4(b) which shows the change in strength of the ferro-coke obtained, the average drum strength (DI(150 / 15)) during this period was 66, which was 17 points higher than when the countermeasure according to the present invention was not applied (comparative example). [Industrial Applicability]

[0026] In the method for producing ferro-coke of the present invention, when a temperature deviation occurs in the horizontal direction inside a vertical carbonization furnace, charging of briquettes from the furnace top, as in normal operation, is switched to charging ferro-coke from the furnace top and cutting it out from the furnace bottom, thereby circulating the ferro-coke from the furnace top to the furnace bottom. This eliminates the deterioration of gas permeability inside the furnace and makes it possible to obtain ferro-coke of stable quality, which is industrially useful. [Explanation of symbols]

[0027] 1 Storage hopper 2 Screen 3 Loading device 4 Vertical Drying Furnace 5 Discharge device 6 1-stage thermometer 7 2-stage thermometer 8 3-stage thermometer 9 4-stage thermometer

Claims

1. A method for producing ferro coke, comprising continuously carbonizing in a vertical carbonization furnace molded materials containing a carbon-containing material and an iron-containing material as a raw material to obtain ferro coke, characterized in that, when a temperature deviation occurs in the horizontal direction inside the vertical carbonization furnace, the molded materials are switched to ferro coke, and the ferro coke is charged from the top of the furnace and cut out from the bottom of the furnace, thereby circulating the ferro coke from the top to the bottom of the furnace.

2. 2. The method for producing ferro coke according to claim 1, wherein the amount of the ferro coke charged from the top of the furnace is set to 0.5 W to W with respect to the amount W (ton) of ferro coke in the furnace during normal operation.

3. 3. The method for producing ferro coke according to claim 1 or 2, characterized in that when the difference between the maximum and minimum temperature values ​​of a plurality of thermometers installed horizontally at a height of not more than 5 m from the furnace top becomes 50° C. or more, the molded material charged from the furnace top is switched to ferro coke.

4. The method for producing ferro-coke according to claim 1 or 2, characterized in that the drum strength (DI (150 / 15)) of the ferro-coke is 76 or more.

5. The method for producing ferro-coke according to claim 3, characterized in that the drum strength (DI (150 / 15)) of the ferro-coke is 76 or more.

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