JP5487790B2 - Ferro-coke manufacturing method - Google Patents

Description

  The present invention relates to a method for producing ferro-coke produced by molding and carbonizing a mixture of a carbon-containing substance and an iron-containing substance, and particularly relates to a binder used for molding a mixture of a carbon-containing substance and an iron-containing substance.

  Ferro-coke is produced by molding and carbonizing a mixture of a carbon-containing material and an iron-containing material. In the ferro-coke manufacturing process using a continuous vertical type carbonization furnace, tar is generated, but this tar is a low-temperature carbonization tar and is not subjected to thermal decomposition at a high temperature. Therefore, it is generally a tar with more aliphatic side chains and lower aromaticity than the tar generated in the chamber furnace coke oven (see Non-Patent Document 1).

  Low-temperature dry distillation tar, which is a by-product of the ferro-coke manufacturing process as described above, is difficult to process with existing distillation equipment, etc., but is a mixture of raw materials containing carbon and iron. About 6% of the amount of material is generated. For this reason, it is desired to effectively use low-temperature carbonized tar in the tar state.

  Low-temperature carbonized tar is modified to increase aromaticity and is used as a pitch raw material for electrodes. As reforming methods, besides the use of a catalyst, there are a thermal reforming method (pyrolysis method) (see Non-Patent Document 2) and an oxidation reforming method. In the thermal reforming method, low-temperature dry distillation tar is reformed by thermal decomposition at about 400 to 500 ° C. On the other hand, the oxidation reforming method is reformed by blowing an oxidizing gas under a lower temperature condition than the thermal reforming method. The oxidation reforming method is used for petroleum residue (see Non-Patent Document 3).

  In order to effectively use low-temperature carbonized tar in the ferro-coke production process, it is considered to be effective means to use it as a fuel or to modify it and use it as a binder. For example, as a technique similar to ferro-coke, in a continuous molding coke process, coal tar pitch, petroleum heavy oil, synthetic polymer, and the like have been studied as molding binders (see Non-Patent Document 4). . In recent years, utilization of low-temperature dry distillation tar oxidation-modified tar as a binder for molded coke has been studied, and the possibility of replacing coal-based soft pitch has been studied (see Non-Patent Document 5).

  On the other hand, in the continuous ferrocoke manufacturing method, petroleum-based pitch and coal-based soft pitch are simultaneously used as a binder for molding a mixture of a carbon-containing material and an iron-containing material as a raw material (see Patent Document 1). ).

JP 2007-277489 A

Kyoritsu Publishing Co., Ltd. “Coal Chemistry” 1960 140 “Chemical Engineering”, 1984, p. 526, vol. 48 Fuel Association "Fuel Association Journal" 1978, p. 75, vol. 57 Japan Iron and Steel Association "Continuous Forming Coke Manufacturing Technology Research Results Report" 1980 310-338 Japan Iron and Steel Association "Iron and Steel" 1996, p. 453, vol. 82, no. 5

  The following (a)-(c) is mentioned as a characteristic of the continuous ferrocoke manufacturing process described in Patent Document 1.

  (A) There are only two openings of the carbonization furnace, that is, the inlet of the molded product, which is a ferro-coke raw material, and the product discharge part, and each is separated from the main body by a double valve. Moreover, since the dry distillation furnace is integrally provided with a cooling unit in addition to the heating unit, the emission of unburned gas is small.

  (B) High reactive coke needs to be produced and used in order to aim for high-low reductant ratio operation in a blast furnace, but ferro-coke can be highly reactive coke.

  (C) Non-micro-coking coal and non-coking coal unsuitable for coke production should be used as raw materials.

  Since the above three points are factors to compensate for the disadvantages of the chamber coke oven, a ferro-coke dry distillation furnace can be developed as an alternative to the chamber oven coke oven, and the ferro-coke production process may be developed. . However, the fact that the chamber-type coke oven is not used means that the production amount of coal-based pitch, which is a binder of the ferro-coke raw material molded product, is reduced. Also, petroleum-based pitch is expected to become difficult to obtain due to future increases in usage. On the other hand, low-temperature dry distillation tar, which is a by-product from the ferro-coke production process, cannot be treated with existing distillation facilities as described above, and therefore it is desirable to make effective use of low-temperature dry distillation tar.

  Therefore, in the present invention, a low temperature carbonization tar generated in the ferrocoke production process is used as a binder for the ferrocoke raw material molding, thereby enabling a ferrocoke production method that can be effectively used in the ferrocoke production process. The purpose is to provide.

The features of the present invention for solving such problems are as follows.
(1) A method for producing ferro-coke by dry distillation of a molded product obtained by mixing a carbon-containing substance and an iron-containing substance, and reforming a low-temperature dry distillation tar generated during the dry distillation to make it heavy A method for producing ferro-coke, characterized in that a modified tar is formed, and the modified tar is used as a binder and mixed with the carbon-containing material and the iron-containing material to form the molded product.
(2) The method for producing ferro-coke according to (1), wherein the low-temperature dry distillation tar is reformed by heating to 200 to 350 ° C. and blowing air.
(3) The modified tar has a softening point in a range of stirring temperature ± 20 ° C. when the modified tar is mixed with a carbon-containing material and an iron-containing material as a binder and molded (1) Or the manufacturing method of the ferro coke as described in (2).

  ADVANTAGE OF THE INVENTION According to this invention, in a ferro-coke manufacturing process, it can utilize effectively as a binder of a ferro-coke raw material molded object, without discarding the low temperature dry distillation tar which generate | occur | produces with dry distillation. Thereby, the usage-amount of the petroleum-type pitch used as a binder and a coal-type pitch can be reduced.

The graph which shows the intensity | strength measurement result of a molding. Schematic of a test apparatus for oxidation reforming. The graph which shows the oxygen concentration (oxygen content) in reformed tar. The graph which shows H / C ratio of a modified tar. The graph which shows the volatile matter in a modified tar. The graph which shows the aromatic carbon fraction in a modified tar. The graph which shows the relationship between the intensity | strength of a molding, and the softening point of a modified tar.

  Ferro-coke is produced by dry distillation of a molded product obtained by mixing a carbon-containing material such as coal and an iron-containing material such as iron ore. In the present invention, low-temperature carbonization tar (hereinafter referred to as “ferrocoke tar”), which is a by-product generated when carbonized material and iron-containing material are carbonized in a carbonization furnace, is referred to as carbon-containing material. When used as a binder of a molded product with an iron-containing substance, ferro-coke tar is modified and a heavy-weight modified tar is used as a binder. By increasing the weight, a component called β-resin that is insoluble in toluene and soluble in quinoline increases, and can be suitably used as a binder.

  The modification of the ferro-coke tar is preferably an oxidation modification by blowing air into the tar. The oxidation modification is preferably performed by heating to 200 to 350 ° C. Since oxidation reforming can be performed under relatively low temperature conditions, the cost is lower than that of thermal reforming.

  The modified ferro-coke tar (modified tar) preferably has a softening point in a range of ± 20 ° C. from the stirring temperature range of the carbon-containing material, the iron-containing material, and the binder when the molded product is molded. When the softening point of the modified tar is within this range, a high-strength molded product can be produced.

  Hereinafter, the present invention will be specifically described.

  Ferro-coke tar (low-temperature carbonization tar) is produced by cooling a gas generated when carbonized and iron-containing materials are carbonized in a vertical carbonization furnace. Since the evolved gas is not subject to high-temperature pyrolysis in the packed bed of the vertical carbonization furnace, ferro-coke tar is produced as low-temperature carbonization tar. Since the generated tar is mixed with water, the ferrocoke tar and water are separated by specific gravity separation.

  Table 1 shows the properties (industrial analysis, elemental analysis values) of petroleum pitch (ASP: softening point 190 ° C), coal-based soft pitch (SOP: softening point 40 ° C), and ferro-coke tar.

  Ferro coke tar is liquid at room temperature. According to Table 1, it can be seen that ferrocoke tar has a higher volatile content and lower fixed carbon than petroleum pitch and coal pitch.

  When such a ferro coke tar is used as a binder in the production of a molded product of a carbon-containing material and an iron-containing material, the strength of the molded product is reduced as compared with the case where a coal-based soft pitch is used. Therefore, in order to use ferro coke tar as a binder, it is considered necessary to modify and make it heavier.

  Ferro coke tar can be modified by blowing air with heating. Even if air blowing is performed, the increase in oxygen in the reformed tar after reforming is small, the H / C ratio decreases, and the hydrogen content decreases. Moreover, the volatile matter in the tar decreases as the heating time increases, the fixed carbon increases, and the heaviness by the heat treatment proceeds with the heating time.

  The softening point of the modified tar obtained by modifying the ferro-coke tar increases as the heating temperature increases and the heating time increases. Aromatization also proceeds.

  Conventionally, petroleum-based pitches and coal-based soft pitches have been used simultaneously as binders in the production of molded articles of carbon-containing materials and iron-containing materials as described above. When the modified tar obtained by modifying ferro-coke tar is used as a binder, it can be used alone, but it is mixed with petroleum-based pitch, mixed with coal-based soft pitch, and petroleum-based pitch. It can also be used as a mixture with both coal-based soft pitches. When the softening point of the modified tar is around the stirring temperature (stirring temperature ± 20 ° C.) for mixing the carbon-containing material, iron-containing material, and binder when molding the molded product, a high-strength molded product is produced. In addition, when mixed with coal-based soft pitch, it is preferable because it liquefies and increases the interaction with coal-based soft pitch.

  Ferro-coke tar (low-temperature carbonized tar) is produced by continuously charging a molded product of coal and iron ore using a continuous vertical furnace with a height of 3000 mm and a diameter of 250 mm and cooling the generated gas. did. Water was separated from the tar produced by specific gravity separation to obtain ferrocoke tar.

The dry distillation of the molded product was performed by setting an electric heating furnace provided at a position 1000 to 1500 mm from the furnace bottom at 900 ° C. and circulating N ₂ gas at 900 ° C. from a position 1250 mm from the furnace bottom.

  The molded product was produced by kneading coal, iron ore, and a binder at 140 to 160 ° C. for about 2 minutes with a high-speed mixer, and using a molding machine. As a binder, in addition to the above-mentioned ferro-coke tar, coal-based soft pitch, coal tar collected in a chamber furnace coke oven is used. 3% by mass of any of the binders was added. Tables 2 and 3 show molding conditions and raw material conditions of the molded product.

  The strength of the manufactured molded product was measured. The strength of the molded product was evaluated by using a type I drum test apparatus (cylindrical shape with an inner diameter of 130 mm × 700 mm) based on a residual rate of 16 mm or more after 30 rotations at a rotation speed of 20 rotations per minute.

  FIG. 1 shows the strength measurement results of a molded product produced using coal-based soft pitch, coal tar, and ferro-coke tar. It can be seen that when coal tar or ferro coke tar is used, the strength of the molded product is lowered, and particularly when ferro coke tar is used, the strength is greatly reduced.

  Next, oxidative reforming by air blowing was performed in order to reform and ferrocoke tar. FIG. 2 shows a test apparatus for oxidation reforming by air blowing. In a separable flask (500 ml) 1, 200 g of ferro coke tar 2 was weighed and set. After setting an air flow rate of 500 ml / min, the temperature was raised to a predetermined reaction temperature (200, 250, 300 ° C.). The generated gas was recovered by the cold trap 3 even during the temperature rise. After reaching the predetermined reaction temperature, the reaction was performed for each reaction temperature level for a predetermined time (0.5 to 5 hr). After completion of the reaction, the reaction mixture was cooled and the mass of ferrocoke tar was measured.

  FIG. 3 shows the oxygen concentration (oxygen content) in the reformed tar after the oxidation reforming. It is thought that the increase in oxygen in the modified tar accompanying air blowing is small.

  FIG. 4 shows the H / C ratio of the modified tar after oxidation reforming. The H / C ratio of the ferro-coke tar before reforming was 1.46, but it can be seen that the hydrogen content is reduced to about 0.80 by oxidative reforming.

  FIG. 5 shows the volatile matter in the reformed tar after oxidation reforming. It can be seen that the volatile matter decreases as the heating time increases and the fixed carbon increases, so that the heaviness due to the heat treatment proceeds with the heating time.

  Table 4 shows the softening point of the modified tar after the oxidation reforming when the heating temperature and the heating time are changed when the ferrocoke tar is subjected to the oxidation reforming.

  It can be seen that the softening point increases as the tar becomes heavier as the heating temperature increases and the heating time increases.

  Next, the average structure index calculated by the Brown-Ladner method obtained from the elemental analysis result and 1H-NMR bond hydrogen fraction of the reformed tar after oxidation reforming was determined. As an example, the result of the aromatic index (aromatic carbon fraction) indicating aromaticity is shown in FIG. Although the aromatic carbon fraction in the ferro-coke tar before reforming is as low as 0.53, the aromatic index became about 0.85 as the heating temperature and heating time increased, indicating that aromatization progressed. .

  Next, 2 mass% of petroleum-based pitch used as a binder is changed to 2 mass% of modified tar, which is a ferro-coke tar after oxidation reforming, and 1 to 3 mass% of coal-based soft pitch is added thereto to produce a molded product. The strength was measured. Molding conditions followed Table 2. The strength of the molded product was measured by using a type I drum test apparatus (cylindrical shape having an inner diameter of 130 mm × 700 mm) based on a residual rate of 16 mm or more after 30 rotations at a rotation speed of 20 rotations per minute. FIG. 7 shows the relationship between the I-type strength of the molded product and the softening point of the modified tar.

  According to FIG. 7, when the coal-based soft pitch is 3 mass%, the strength of the molded product increases until the softening point of the modified tar reaches 120 ° C., becomes almost constant from 130 to 180 ° C., and is molded at 190 ° C. or higher. The strength decreased. The strength of the molded product was high at 130 to 180 ° C., because the stirring temperature between the binder and the raw material was 140 to 160 ° C., and it was assumed that the modified tar was liquefied and the interaction with the coal-based soft pitch was increased. The On the other hand, when the softening point of the modified tar is low, there are few components that enhance the binder performance in the modified tar, and when the softening point of the modified tar is high, the modified tar does not dissolve, so it is presumed that the strength has decreased. Further, according to FIG. 7, it is considered that a modified tar having a softening point in the range of about ± 20 ° C. from the stirring temperature range of the binder and the raw material (shaded portion in FIG. 7) can be used as a molding binder. .

  The strength test of the molded product when the addition rate of coal-based soft pitch is reduced to 1, 2% by mass shows that the modified tar can be suitably used as a molding binder, and the softening point of the modified tar is 130 to 180 ° C. Went in the range. According to FIG. 7, the strength decreased when the coal-based soft pitch was 1 mass%, while the strength was maintained at 3 mass% when the mass was 2 mass%, and the petroleum-based pitch was selected by appropriately selecting the softening point of the modified tar. It was found that the addition rate of coal-based soft pitch can be reduced.

DESCRIPTION OF SYMBOLS 1 Separable flask 2 Ferro coke star 3 Cold trap 4 Heater 5 Thermometer 6 Dimroth 7 Gas blowing pipe 8 Cooling water pipe 9 Liquid nitrogen trap 10 Trap (liquid paraffin)
11 Air cylinder 12 Flow meter 13 Two-way cock

Claims (2)

A method for producing ferro-coke by dry-distilling a molded product obtained by mixing a carbon-containing material and an iron-containing material,
The low-temperature dry distillation tar generated during the dry distillation is reformed into a heavy reformed tar,
Using the modified tar as a binder, the carbon-containing substance and the iron-containing substance are stirred and mixed during the molding,
A method for producing ferro-coke, wherein the modified tar has a softening point in a range of a stirring temperature of ± 140 ° C within a range of 140 to 160 ° C.   The method for producing ferro-coke according to claim 1, wherein the reforming of low-temperature dry distillation tar is performed by heating to 200 to 350 ° C and blowing air.

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