JP2018024896A - Manufacturing method of reduced iron, manufacturing method of molten steel and blast furnace iron mill including reduced iron manufacturing process - Google Patents

Abstract

[PROBLEMS] To effectively utilize COG, which is a reducing gas discharged from a steelmaking process equipped with a blast furnace, as a reducing material, to optimize the use of energy at a steelworks and to cope with future deterioration of raw materials. Like that. In a steelworks 1 equipped with a blast furnace 2, a coke oven gas produced as a by-product in a coke oven 4 for producing coke supplied to the blast furnace 2 is used as a reducing material, and a shaft furnace 11 or a fluidized bed type reduction furnace. The reduced iron is produced by the above, and the amount of coke supplied to the blast furnace 2 is obtained from the output capacity of the blast furnace 2, and then the amount of coke oven gas produced as a by-product when producing the amount of coke is obtained. In the shaft furnace 11 or the fluidized bed type reducing furnace, the equipment capacity of the shaft furnace 11 or the fluidized bed type reducing furnace is determined according to the amount of reduced iron that can be reduced with the amount of coke oven gas. [Selection] Figure 2

Description

  TECHNICAL FIELD The present invention relates to a method for producing reduced iron, a method for producing molten steel, and a blast furnace ironworks including a reduced iron production process. Specifically, a blast furnace and a shaft furnace or a fluidized bed type reduction furnace using coke oven gas as a reducing material. The present invention relates to a method for producing reduced iron or molten steel in combination and a blast furnace steel works.

  In a large-scale blast furnace method based on a large blast furnace, molten iron is produced by charging a blast furnace with sintered ore fired from iron ore in a sintering furnace and coke produced by steaming coking coal in a coke furnace. The hot metal is refined with oxygen in a converter to produce molten steel. At that time, coke oven gas (COG) generated in the coke oven and blast furnace gas (BFG) generated in the blast furnace are conventionally used as a heating furnace in a lower process such as hot rolling or as a fuel for private power generation.

  However, in the large blast furnace process, if high-quality iron ore and high-quality coking coal are not mixed at a certain ratio or more, the operation becomes unstable. There is a concern that it will worsen and operation will become difficult. For example, from the viewpoint of securing the strength of sintered ore, there is a limit to the blending ratio of fine ore. Therefore, taking into account the deterioration of raw materials such as iron ore and coking coal that are expected to be available in Japan in the near future, the high-efficiency ironmaking method using large blast furnaces and high-quality raw materials that will become the mainstream will last in the future. The possibility is small, and it will be necessary to use a process such as a shaft furnace that can use inferior raw materials.

  Further, COG is a strongly reducing gas containing about 50 to 55% of hydrogen and capable of reducing iron oxide alone, and the value of COG cannot be fully utilized only by burning it as fuel. In other words, the current blast furnace method leaves room for optimization as a steelmaking process.

  In Patent Document 1, the heat of the exhaust gas from the coal gasification process is recovered by a waste heat boiler to generate steam, and the steam is directly heated by the exhaust gas from the iron making process, and the superheated steam is used as an oxidizing agent in the coal gasification furnace. A method is described in which the product gas produced by coal gasification is supplied as fuel directly to the heating and reduction furnace of the iron making process.

  In Patent Document 2, oxygen is blown into a solid carbon material in a vertical gasification furnace with a lance to gasify it, and the gas and the iron ore are heated to 600 ° C. or higher and the metallization rate is 0.4 or higher and 0. A method for producing a prereduced agglomerated product in which a prereduced product of .8 or less is produced, the prereduced product is classified into coarse particles and fine particles, and the fine particles are agglomerated is disclosed.

  Patent Document 3 discloses a direct reduction shaft furnace that uses iron oxide to reduce iron oxide to metallic iron. Patent Document 4 discloses a direct reduction shaft furnace that uses a coke oven gas (COG) and a basic oxygen steelmaking furnace gas (BOFG) to reduce iron oxide to metallic iron, and removes carbon dioxide from a mixture of BOFG. It is described.

  Patent Document 5 discloses a method of reducing iron ore using a direct reduction method, in which a reducing gas is added to exhaust gas and then reheated by electricity to be reused as the reducing gas.

Patent Document 6 discloses a method for producing reduced iron that supplies a reduced gas containing a by-product gas containing at least one of H ₂ and CO generated in an iron making process as a part to a reduced iron production apparatus. Is described as containing by-product gas generated from a coke oven.

Japanese Patent No. 4712082 Japanese Patent No. 5598423 Japanese Patent No. 5713709 Japanese Patent No. 583214 JP-T-2015-532948 International Publication No. 2011/099070

  However, the above-mentioned Patent Document 1 generates steam through coal gasification exhaust gas through a boiler or heat exchange, and does not relate to effective use of COG, which is a reducing gas discharged from the iron making process. Moreover, although the exhaust gas of a rotary hearth furnace (RHF) is used to superheat the steam, it is not necessarily a direct reduction process.

  In Patent Document 2, iron ore is reduced in a shaft furnace or the like using a reducing gas derived from coal. However, in order to generate the reducing gas, it is necessary to newly use a solid carbon material.

  Patent Document 3 and Patent Document 4 relate to a shaft furnace and its peripheral equipment, and do not relate to the effective use of COG by-produced from a blast furnace in the shaft furnace. Patent Document 5 also does not relate to effective use of COG by-produced from equipment equipped with a blast furnace.

  Patent Document 6 describes reforming as a reducing gas, including by-product gas such as COG, as well as gas obtained from gasification of natural gas and steam coal, and by-product from equipment equipped with a blast furnace. It is not related to the effective utilization of the amount of COG produced in the shaft furnace without excess or deficiency.

  The purpose of the present invention is to effectively utilize COG, which is a reducing gas discharged from an ironmaking process equipped with a blast furnace, as a reducing material, to optimize energy use in steelworks, and to reduce the quality of raw materials in the future. Is to be able to cope.

  In order to solve the above problems, the present invention provides a shaft furnace or a fluidized bed using, as a reducing material, a coke oven gas produced as a by-product in a coke oven for producing coke to be supplied to the blast furnace in an iron works equipped with a blast furnace. Reduced iron is produced in a reduction furnace, and the amount of coke supplied to the blast furnace is determined from the output capacity of the blast furnace, and then the amount of coke oven gas produced as a by-product when the amount of coke is produced, Next, in the shaft furnace or the fluidized bed type reduction furnace, the facility capacity of the shaft furnace or the fluidized bed type reduction furnace is determined according to the amount of reduced iron that can be reduced by the coke oven gas amount. A method for producing reduced iron is provided.

In the method for producing reduced iron, the equipment capacity P _D (t / Yr) of the shaft furnace or fluidized bed type reduction furnace may be obtained by the following equation.
P _D = P _P × F _COG × ((C _CO + _{CH 2} + 3 × C _{CH 4} ) ÷ 100) × (η ÷ 100) ÷ F _O ÷ 22.4 × 16.0 (1)
here,
P _P : Blast furnace tapping capacity (t / Yr)
F _COG : COG generation amount per ton of hot metal in the blast furnace (Nm ³ / t)
C _CO : CO content in COG (% by volume)
C _H2 : H ₂ content in COG (% by volume)
C _CH4 : CH ₄ content (% by volume) in COG
η: COG utilization efficiency in shaft furnace or fluidized bed type reduction furnace (%)
F _O: In a shaft furnace or a fluidized bed reduction furnace, the reduced iron mass of oxygen that must be removed when 1t produced (kg-O 2 / _t)
Note that _FO is determined by the quality of the ore used in the shaft furnace or the fluidized bed reduction furnace and the target reduction rate of the product reduced iron.

  Further, the present invention is characterized in that the reduced iron produced by the method for producing reduced iron and the molten iron produced in the blast furnace are mixed and put into a refining furnace, and finish reduction and refining are performed. A manufacturing method is provided.

  Further, the reduced iron produced by the method for producing reduced iron is hot-molded into HBI, and the hot metal produced in the blast furnace is charged into the smelting furnace using the HBI as a raw material for the blast furnace, and finish reduction and refining are performed. A method for producing molten steel is provided.

  Furthermore, the reduced iron produced by the method for producing reduced iron is hot-molded to form HBI, the HBI is sieved, the sieving portion is used as the raw material of the blast furnace, and the molten iron produced in the blast furnace is used as the hot metal. Provided is a method for producing molten steel, which is mixed and charged into a refining furnace to perform finish reduction and refining.

  Furthermore, the present invention provides a coke oven for producing coke to be supplied to the blast furnace, and a shaft for producing reduced iron using a coke oven gas by-produced in the coke oven as a reducing material in an ironworks equipped with a blast furnace. A coke oven that is by-produced when producing the amount of coke to be supplied to the blast furnace, which is obtained from the output capacity of the blast furnace. Provided is a blast furnace steelworks including a reduced iron production process, which has a facility capacity corresponding to the amount of reduced iron that can be reduced by a gas amount.

In the blast furnace steelworks including the reduced iron manufacturing process, the facility capacity P _D (t / Yr) of the shaft furnace or fluidized bed type reduction furnace may be obtained by the following equation.
P _D = P _P × F _COG × ((C _CO + _{CH 2} + 3 × C _{CH 4} ) ÷ 100) × (η ÷ 100) ÷ F _O ÷ 22.4 × 16.0 (1)
here,
P _P : Blast furnace tapping capacity (t / Yr)
F _COG : COG generation amount per ton of hot metal in the blast furnace (Nm ³ / t)
C _CO : CO content in COG (% by volume)
C _H2 : H ₂ content in COG (% by volume)
C _CH4 : CH ₄ content (% by volume) in COG
η: COG utilization efficiency in shaft furnace or fluidized bed type reduction furnace (%)
F _O: In a shaft furnace or a fluidized bed reduction furnace, the reduced iron mass of oxygen that must be removed when 1t produced (kg-O 2 / _t)

  According to the present invention, in a steel mill equipped with a blast furnace, by providing a shaft furnace or a fluidized bed type reduction furnace corresponding to the blast furnace's tapping capacity, COG by-produced in the coke oven can be used as a reducing material without excess or deficiency. It can be used effectively. Therefore, it is possible to optimize the energy use of the steelworks and cope with future deterioration of raw materials.

It is a block diagram which shows the structure and process of the steelworks concerning the 1st Embodiment of this invention. It is a graph which shows the relationship between the blast furnace discharge capability and vertical shaft furnace installation capability in 1st Embodiment. It is a block diagram which shows the structure and process of the steelworks concerning the 2nd Embodiment of this invention. It is a graph which shows the relationship between the blast furnace outflow capability and the vertical shaft furnace installation capability in 2nd Embodiment. It is a block diagram which shows the structure and process of the steel mill concerning the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted. In the following embodiment, an example of a vertical shaft furnace is described as a furnace using COG as a reducing material, but the same can be applied to a fluidized bed type reducing furnace.

<1. First Embodiment>
FIG. 1 shows an outline of the structure and process of an ironworks according to a first embodiment of the present invention.

  The ironworks 1 is provided with a blast furnace 2, and further includes a sintering furnace 3 for firing iron ore to produce sintered ore, and a coke furnace 4 for producing coke from raw coal. Sinter ore and coke are charged into the blast furnace 2, and hot metal is produced in the blast furnace 2. The hot metal is refined in a refining furnace 7 comprising a converter 5 or an electric furnace 6 to produce molten steel. Blast furnace gas (hereinafter referred to as BFG) by-produced in the blast furnace 2 is used as fuel for the power plant 10 for the heating furnace 9 and private power generation.

  In the present embodiment, the shaft-type shaft furnace 11 capable of reducing powder ore in the same site as the blast furnace 2 or in the vicinity of the installation location of the blast furnace 2 of the steel works 1 based on the blast furnace 2 is provided. Is provided. The shaft furnace 11 is charged with powdered ore that is difficult to use in the blast furnace 2 by pre-treatment, for example, by pelletization, and reduced iron is produced by adding a reducing material. By providing such a shaft furnace 11, the width of the raw material properties that can be used at the steelworks 1 can be expanded, and the deterioration of raw materials such as iron ore and raw coal can be dealt with.

  As the reducing material in the shaft furnace 11, coke oven gas (hereinafter referred to as COG) by-produced in the coke oven 4 is used. The COG used as the reducing material may be discharged from the coke oven 4 or may be used after being reformed. A part of the COG may be used as a fuel for the coke oven 4 and the sintering furnace 3.

  The equipment capacity of the shaft furnace 11 is set according to the amount of COG generated in the steelworks 1. That is, first, the amount of coke required to supply to the blast furnace 2 is obtained from the output capacity of the blast furnace 2. Next, the amount of COG by-produced from the coke oven 4 when the amount of coke is produced is determined. The amount of COG that can be supplied to the shaft furnace 11 is a shaft furnace 11 having an equipment capacity such that the amount of reducing material necessary for the amount of reduced iron that can be reduced in the shaft furnace 11 is substantially the same. By determining the equipment capacity of the shaft furnace 11 in this way, COG can be utilized most effectively without excess or deficiency.

Conventionally, in a steel mill, COG is used as a fuel for the heating furnace 9 and is not used as a reducing gas. On the other hand, as the reducing agent of the shaft furnace 11, or using natural gas, coal has been or synthesis gas mixture of CO and H ₂ by gasification. In the present embodiment, inexpensive steam coal is supplied as a fuel to a heating furnace or a power plant that uses COG as a fuel in a conventional steel mill. Further, BFG produced as a by-product in the blast furnace 2 is used as fuel for the heating furnace 9 and the power plant 10 as usual. Thereby, COG which is a strong reducing gas is effectively used as a reducing gas in the shaft furnace 11.

  The reduced iron produced in the shaft furnace 11 is refined in a refining furnace 7 composed of an electric furnace 6 or a converter 5. In other words, the reduced iron is put into the electric furnace 6 as it is, or is compressed and hardened into a hot briquette (HBI), and HBI is put into the converter 5 together with the hot metal produced in the blast furnace 2 and refined in the refining furnace 7. To produce molten steel.

  FIG. 2 shows the relationship between the output capacity of the blast furnace 2 and the equipment capacity of the shaft furnace 11 in the present embodiment.

  When reducing iron produced in the shaft furnace 11 and molten iron produced in the blast furnace 2 are mixed and refined in the smelting furnace 7 to produce molten steel, supply capacity of the blast furnace 2 and coke are supplied to the blast furnace 2. The relationship with the facility capacity of the vertical shaft furnace 11 estimated from the amount of reduced iron that can be reduced by the amount of COG generated from the coke oven 4 was obtained by simulation. In FIG. 2, the solid line indicates the case where the entire amount of COG generated in the coke oven 4 is used as the reducing material of the shaft furnace 11, and the dotted line indicates that the COG used in the coke oven 4 and the sintering furnace 3 is preferentially there. A case is shown in which the excess COG is supplied to the shaft furnace 11. The alternate long and short dash line indicates the minimum capacity of an existing vertical shaft furnace as a commercial process.

The equipment capacity P _D (t / Yr) of the shaft furnace or fluidized bed type reduction furnace was determined by the following formula.
P _D = P _P × F _COG × ((C _CO + _{CH 2} + 3 × C _{CH 4} ) ÷ 100) × (η ÷ 100) ÷ F _O ÷ 22.4 × 16.0 (1)
here,
P _P : Blast furnace tapping capacity (t / Yr)
F _COG : COG generation amount per ton of hot metal in the blast furnace (Nm ³ / t)
C _CO : CO content in COG (% by volume)
C _H2 : H ₂ content in COG (% by volume)
C _CH4 : CH ₄ content (% by volume) in COG
η: COG utilization efficiency in shaft furnace or fluidized bed type reduction furnace (%)
F _O: In a shaft furnace or a fluidized bed reduction furnace, the reduced iron mass of oxygen that must be removed when 1t produced (kg-O 2 / _t)

In carrying out the simulation, when the total amount of COG generated in the coke oven 4 is used as the reducing material of the shaft furnace 11, F _COG = 158.3 (Nm ³ / t), C _CO = 6 in the equation (1). 0.5%, C _H2 = 55%, C _CH4 = 27%, η = 75%, F 2 _O = 434 (kg-O ₂ / t). Further, when COG used in the coke oven 4 and the sintering furnace 3 is preferentially supplied to the coke oven 4 and surplus COG is supplied to the shaft oven 11, F _COG = 130.6 ( Nm ³ / t), C _{CO 2} = 6.5%, C _H2 = 55%, C _CH4 = 27%, η = 75%, F 2 _O = 434 (kg-O ₂ / t).

  When the steelworks 1 has a blast furnace 2 with a certain output capacity or is newly installed, COG produced as a by-product from the coke oven 4 for producing coke to be supplied to the blast furnace 2 can be used as a reducing material without excess or deficiency. The equipment capacity of the shaft furnace 11 that can be utilized is defined by the solid line shown in FIG. When the shaft furnace 11 larger than this solid line is installed, the COG produced as a by-product from the coke oven 4 alone is insufficient for the necessary reducing material, so it is necessary to provide a separate coal gasification facility and natural gas supply base. Resulting in a surge in equipment costs.

  On the other hand, in the steelworks 1, when it is not possible to supply fuel gas other than COG to the coke oven 4 and the sintering furnace 3 due to piping facilities, etc., COG must be preferentially supplied to these processes. The amount of COG that can be supplied to the shaft furnace 11 decreases. In that case, the maximum facility capacity of the shaft furnace 11 determined from the amount of COG decreases to the dotted line in FIG.

  When the shaft furnace 11 smaller than the facility capacity shown by the solid line or the dotted line in FIG. 2 is installed, the COG becomes surplus in any case, but this surplus COG is used as fuel gas for the heating furnace 9 and the like as usual. Because it can be used, there will be no major disadvantages. However, when the shaft furnace 11 having an equipment capacity of less than 0.3 (Mt-DRI / y) shown by the one-dot chain line in FIG. 2 is installed, the ratio of the furnace body surface area to the furnace volume is large, and the heat transfer efficiency is deteriorated. Not economical. Therefore, from the viewpoint of thermoeconomic rationality, it is preferable that the lower limit of the equipment capacity of the newly installed shaft furnace 11 is 0.3 (Mt-DRI / y) or more indicated by a one-dot chain line in FIG. In other words, depending on the output capacity of the existing or newly installed blast furnace 2, the installation of the shaft furnace 11 having the facility capacity in the region between the solid line or the dotted line and the one-dot chain line in FIG. It is preferable from the viewpoint of effective use of COG. Note that the solid line and the dotted line change depending on the amount of coke used in the blast furnace 2, the composition of COG, and the reduction rate of reduced iron produced in the shaft furnace 11.

<2. Second Embodiment>
FIG. 3 shows an outline of the structure and process of the steel mill showing the second embodiment according to the present invention, and FIG. 4 shows the output capacity of the blast furnace 2 and the equipment of the shaft furnace 11 in the second embodiment. Shows the relationship with ability.

  This embodiment is the same as the embodiment shown in FIG. 2 described above, and the structure of the steelworks 1 is the same, but as shown in FIG. 3, the reduced iron produced in the shaft furnace 11 is hot compressed to produce HBI. The density and strength are increased, and HBI is fed into the blast furnace 2 as a blast furnace raw material. The hot metal produced in the blast furnace 2 is subjected to oxygen refining in a refining furnace 7 comprising a converter 5 or an electric furnace 6 to produce molten steel.

  FIG. 4 shows the shaft furnace 11 of the present embodiment in which the output capacity of the blast furnace 2 and the amount of COG generated from the coke oven 4 that supplies coke to the blast furnace 2 are estimated from the amount of reduced iron that can be just reduced. The relationship with the equipment capacity is obtained by simulation. The meanings of the solid line, the dotted line, and the alternate long and short dash line are the same as those in FIG.

In carrying out the simulation, when the total amount of COG generated in the coke oven 4 is used as the reducing material of the shaft furnace 11, F _COG = 134.8 (Nm ³ / t), C _CO = 6 in the equation (1). 0.5%, C _H2 = 55%, C _CH4 = 27%, η = 75%, F 2 _O = 434 (kg-O ₂ / t). Further, when COG used in the coke oven 4 and the sintering furnace 3 is preferentially supplied to the coke oven 4 and surplus COG is supplied to the shaft oven 11, F _COG = 112.2 ( Nm ³ / t), C _{CO 2} = 6.5%, C _H2 = 55%, C _CH4 = 27%, η = 75%, F 2 _O = 434 (kg-O ₂ / t).

  Also in the case of the present embodiment, it is possible to install the shaft furnace 11 having the facility capacity in the region between the solid line in FIG. 4 or the dotted line and the alternate long and short dash line according to the output capacity of the existing or newly installed blast furnace 2. preferable. In FIG. 4, the facility capacity of the largest shaft furnace that can be installed in a blast furnace having the same tapping capacity is smaller than that in FIG. This is because HBI, which consumes less reducing material, is introduced into the blast furnace 2, so that even if the amount of the same output is reduced, the amount of reducing material (coke) required in the blast furnace 2 is reduced. This is because the amount of COG produced is reduced.

  In the case of the present embodiment, there is a merit that the operation of the refining furnace 7 is more stable than the first embodiment described above. That is, since the reduced iron produced in the shaft furnace 11 is charged as HBI into the blast furnace 2, only the molten iron discharged from the blast furnace 2 is supplied to the smelting furnace 7. Therefore, it is not necessary to mix hot metal and reduced iron in the smelting furnace 7 or to carry out a final reduction reaction of the reduced iron. This not only stabilizes the smelting time but also supplies iron oxide into the smelting furnace 7. Minimized and can prevent refractory from melting. Also in the present embodiment, the solid and dotted lines in FIG. 4 vary depending on the amount of coke used in the blast furnace 2, the composition of COG, and the reduction rate of reduced iron produced in the shaft furnace 11.

<3. Third Embodiment>
FIG. 5 shows the outline of the structure and process of an ironworks showing a third embodiment according to the present invention.

  Conventionally, when reducing iron is produced in the shaft furnace 11, it is generally mixed with hot metal in the refining furnace 7 such as the converter 5 or the electric furnace 6 and refined to obtain molten steel as in the first embodiment. Is. However, when the ratio of reduced iron input in the smelting furnace 7 increases, when the reduction rate of the reduced iron fluctuates due to fluctuations in the operation of the shaft furnace 11, the operation of the smelting furnace 7 becomes unstable, and the amount of reduced iron input increases. An upper limit occurs. Further, if a high reduction rate is aimed at in order to stabilize the operation of the refining furnace 7, there is a concern that the productivity of the shaft furnace 11 may be lowered.

  Therefore, in the present embodiment, the reduced iron produced in the shaft furnace 11 is hot-molded into HBI, and further subjected to sieving using, for example, a sieve 21 having a size of about 40 to 50 mm, which is equivalent to sintered ore. Then, the sieving portion (product HBI) is used as a blast furnace raw material together with the sintered ore and charged into the blast furnace 2. Since the product HBI is sufficiently reduced, it is not necessary to reduce it again in the blast furnace 2, and as a result, the amount of tapping from the blast furnace 2 can be increased while maintaining stable blast furnace operation. On the other hand, since the unsieved portion (powder HBI) of the sieve 21 is unreduced and has low strength, it cannot be reused as a blast furnace raw material. Therefore, this powder HBI is charged into the smelting furnace 7 and melted after finishing reduction. When HBI having a low reduction rate is charged into the smelting furnace 7, there is a concern that the operation of the smelting furnace 7 becomes unstable. However, if only the amount under the sieve is used, the amount is small, and the influence can be minimized. Moreover, according to the operation state of the smelting furnace 7, you may operate by adjusting the presence or absence of injection | pouring of powder HBI. In addition, in this Embodiment, the structure of the steelworks 1 other than a sieving process is the same as that of embodiment shown in above-mentioned FIG. 1, FIG.

  As described above, according to the present invention, by-product gas generated in the iron making process by the blast furnace 2 is used without excess or deficiency, another iron making process by the shaft furnace 11 is efficiently operated, and the energy utilization of the steel works 1 is performed. Can be optimized. Furthermore, by using both the blast furnace 2 and the shaft furnace 11 in the steelworks 1, it is possible to produce molten steel from raw materials of quality that cannot be handled in the blast furnace 2 in one steelworks 1, and to handle various raw materials. It becomes like this.

  When COG is not generated as a by-product due to maintenance of the blast furnace 2 or the like, natural gas that has been conventionally used as a reducing material or synthesis gas generated from coal may be used as the reducing material of the shaft furnace 11.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the above embodiment, an example of the vertical shaft furnace 11 is described as a furnace using COG as a reducing material, but the same can be applied to the fluidized bed type reducing furnace 12.

  The present invention is suitable for an ironworks equipped with a blast furnace and a shaft furnace or a fluidized bed type reduction furnace that produces reduced iron using a reducing gas.

DESCRIPTION OF SYMBOLS 1 Steelworks 2 Blast furnace 3 Sintering furnace 4 Coke oven 5 Converter 6 Electric furnace 7 Refining furnace 11 Shaft furnace 12 Fluidized bed type reduction furnace 21 Sieve

Claims (7)

In a steelworks equipped with a blast furnace, coke oven gas produced as a by-product in a coke oven for producing coke supplied to the blast furnace is used as a reducing material, and reduced iron is produced in a shaft furnace or a fluidized bed type reduction furnace,
From the output capacity of the blast furnace, obtain the amount of coke to be supplied to the blast furnace,
Next, determine the amount of coke oven gas produced as a by-product when producing the amount of coke,
Next, in the shaft furnace or the fluidized bed type reduction furnace, the facility capacity of the shaft furnace or the fluidized bed type reduction furnace is determined according to the amount of reduced iron that can be reduced by the coke oven gas amount. A method for producing reduced iron. The method for producing reduced iron according to claim 1, wherein the equipment capacity P _D (t / Yr) of the shaft furnace or the fluidized bed type reduction furnace is obtained by the following formula.
P _D = P _P × F _COG × ((C _CO + _{CH 2} + 3 × C _{CH 4} ) ÷ 100) × (η ÷ 100) ÷ F _O ÷ 22.4 × 16.0 (1)
here,
P _P : Blast furnace tapping capacity (t / Yr)
F _COG : COG generation amount per ton of hot metal in the blast furnace (Nm ³ / t)
C _CO : CO content in COG (% by volume)
C _H2 : H ₂ content in COG (% by volume)
C _CH4 : CH ₄ content (% by volume) in COG
η: COG utilization efficiency in shaft furnace or fluidized bed type reduction furnace (%)
F _O: the shaft furnace or a fluidized bed reduction furnace, the reduced iron mass of oxygen that must be removed when 1t produced (kg-O 2 / _t) The reduced iron produced by the method for producing reduced iron according to claim 1 or 2 and the molten iron produced in the blast furnace are mixed and charged into a refining furnace, and finish reduction and refining are performed. A method for producing molten steel. The reduced iron produced by the method for producing reduced iron according to claim 1 or 2 is hot-molded into HBI, and hot metal produced in the blast furnace is charged into the smelting furnace using the HBI as a raw material for the blast furnace. A method for producing molten steel, characterized by performing finish reduction and refining. The reduced iron produced by the method for producing reduced iron according to claim 1 or 2 is hot-molded to form HBI, the HBI is sieved, the fraction on the sieve is used as a raw material for the blast furnace, Is mixed with hot metal produced in the blast furnace and charged into a refining furnace, and finish reduction and refining are performed. In a steelworks equipped with a blast furnace, a coke oven that produces coke to be supplied to the blast furnace, and a shaft furnace or fluidized bed type reduction that produces reduced iron using coke oven gas by-produced in the coke oven as a reducing material. A furnace,
The shaft furnace or fluidized bed type reduction furnace is
It has a facility capacity according to the amount of reduced iron that can be reduced by the amount of coke oven gas produced as a by-product when producing the amount of coke to be supplied to the blast furnace, which is obtained from the output capacity of the blast furnace. Blast furnace steelworks including iron manufacturing process. The blast furnace ironworks including the reduced iron manufacturing process according to claim 6, wherein the equipment capacity P _D (t / Yr) of the shaft furnace or the fluidized bed type reducing furnace is obtained by the following formula.
P _D = P _P × F _COG × ((C _CO + _{CH 2} + 3 × C _{CH 4} ) ÷ 100) × (η ÷ 100) ÷ F _O ÷ 22.4 × 16.0 (1)
here,
P _P : Blast furnace tapping capacity (t / Yr)
F _COG : COG generation amount per ton of hot metal in the blast furnace (Nm ³ / t)
C _CO : CO content in COG (% by volume)
C _H2 : H ₂ content in COG (% by volume)
C _CH4 : CH ₄ content (% by volume) in COG
η: COG utilization efficiency in shaft furnace or fluidized bed type reduction furnace (%)
F _O: In a shaft furnace or a fluidized bed reduction furnace, the reduced iron mass of oxygen that must be removed when 1t produced (kg-O 2 / _t)

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