JP-2026075195-A - Method of charging raw materials into a blast furnace

JP2026075195AJP 2026075195 AJP2026075195 AJP 2026075195AJP-2026075195-A

Abstract

[Problem] To provide a blast furnace raw material charging method that allows reduced iron to be charged into the part of the furnace with a large reduction load in the radial direction without having to install a dedicated hopper at the top of the furnace. [Solution] This method involves mixing ore raw materials and reduced iron and charging them into a bellless blast furnace. When charging the ore raw materials into one of the furnace top bunkers using a charging conveyor, reduced iron is cut onto the ore raw materials being transported by the charging conveyor. This causes the reduced iron to be layered on the ore raw materials in a length range of 18% to 75% of the total length of the ore raw materials, from the leading end in the transport direction. The ore raw materials and reduced iron are then charged into the furnace top bunker in this state. When loading the raw materials from the furnace top bunker into the furnace using a rotating chute, the rotating chute is rotated and tilted to move the raw material charging position from the middle of the furnace towards the furnace wall while charging the raw materials. [Selection Diagram] Figure 2

Inventors

井川大輔
細川敦司
柏原佑介

Assignees

ＪＦＥスチール株式会社

Dates

Publication Date: 20260508
Application Date: 20241022

Claims (12)

In a bellless blast furnace having multiple top bunkers arranged in parallel and a raw material charging device that charges raw materials into the furnace by a swirling chute, a method for charging a blast furnace by mixing ore raw materials (a) including at least one of sintered ore, pellets and lump ore, and metallic iron raw materials (b) including reduced iron and/or granular pig iron, When transporting the ore raw material (a) to the top of the furnace by a charging conveyor and charging it into one of the top furnace bunkers, the metallic iron raw material (b) is cut out onto the ore raw material (a) being transported by the charging conveyor, so that the metallic iron raw material (b) is stacked on the ore raw material (a) in a length range of 18% to 75% of the total length of the ore raw material (a) loaded on the charging conveyor, from the leading edge in the transport direction, and the ore raw material (a) and metallic iron raw material (b) are then charged into the top furnace bunker. A method for charging raw materials into a blast furnace, characterized in that when charging raw materials from the furnace top bunker into the furnace using the rotating chute, the rotating chute is rotated and tilted to move the raw material charging position from the middle of the furnace to the furnace wall side while charging the raw materials.
In a bellless blast furnace having multiple top bunkers arranged in parallel and a raw material charging device that charges raw materials into the furnace by a swirling chute, a method for charging a blast furnace by mixing ore raw materials (a) including at least one of sintered ore, pellets and lump ore, and metallic iron raw materials (b) including reduced iron and/or granular pig iron, When transporting the ore raw material (a) to the top of the furnace by a charging conveyor and charging it into one of the top furnace bunkers, the metallic iron raw material (b) is cut out onto the ore raw material (a) being transported by the charging conveyor, so that the metallic iron raw material (b) is stacked on the ore raw material (a) in a length range of 18% to 75% of the total length of the ore raw material (a) loaded on the charging conveyor, from the leading edge in the transport direction, and the ore raw material (a) and metallic iron raw material (b) are then charged into the top furnace bunker. A method for charging raw materials into a blast furnace, characterized in that, when charging raw materials from the top bunker into the furnace using the rotating chute, the rotating chute is rotated and tilted to move the raw material charging position from the middle of the furnace to the furnace wall side while charging the raw materials, and then the chute is turned back and the raw materials are charged from the furnace wall side to the middle of the furnace side.
A method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that, when transporting ore raw materials (a) to the furnace top using the charging conveyor and charging them into one of the furnace top bunkers, metallic iron raw materials (b) are stacked on top of the ore raw materials (a) in a length range of 32% to 61% of the total length of the ore raw materials (a) loaded on the charging conveyor, where the distance from the leading end in the transport direction is within that range.
When loading one charge's worth of ore raw materials (a) into the furnace in two batches, A method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that a second batch of ore raw materials (a) is mixed with metallic iron raw materials (b) and charged into the furnace.
The method for charging raw materials into a blast furnace according to claim 4, characterized in that the first batch of ore raw materials (a) is charged into the furnace without mixing it with metallic iron raw materials (b).
A segregation control plate is installed inside the furnace top bunker. The method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that when charging the ore raw materials (a) and metallic iron raw materials (b) transported by the charging conveyor into the furnace top bunker, the raw material receiving surface of the segregation control plate faces outward in the furnace radial direction and is inclined downward with respect to the outward direction of the furnace, causing the raw materials falling from above to fall downward via the raw material receiving surface of the segregation control plate and accumulate in the bunker.
A method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that the average apparent density [ρ b ] of the metallic iron raw material (b) is greater than the average apparent density [ρ a ] of the ore raw material (a).
The method for charging raw materials into a blast furnace according to claim 7, characterized in that the ratio [ρ b ]/[ρ a ] of the average apparent density [ρ b ] of the metallic iron raw material (b) to the average apparent density [ρ a ] of the ore raw material (a) is 1.25 or more.
The method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that the aspect ratio of the metallic iron raw material (b) is 1.4 or greater.
A method for charging raw materials into a blast furnace according to claim 1 or 2, characterized in that the average particle size [d b ] of the metallic iron raw material (b) is greater than the average particle size [d a ] of the ore raw material (a).
The method for charging raw materials into a blast furnace according to claim 10, characterized in that the ratio [d b ]/[d a ] of the average particle size [d b ] of the metallic iron raw material (b) to the average particle size [d a ] of the ore raw material (a) is 3.5 or more.
A method for producing molten iron, characterized by comprising the step of charging a blast furnace with a blast furnace by a raw material charging method according to claim 1 or 2, comprising the step of mixing an ore raw material (a) containing at least one of sintered ore, pellets, and lump ore, and a metallic iron raw material (b) containing reduced iron and/or granular pig iron.

Description

This invention relates to a method for charging raw materials into a bellless blast furnace to obtain a desired charge distribution. In recent years, global warming caused by increased CO2 emissions has become a problem, and controlling CO2 emissions is also an important issue for the steel industry. The majority of CO2 emitted from steel mills comes from blast furnaces. Reducing CO2 emissions from blast furnaces is possible by reducing the amount of reducing agents (coke, pulverized coal, natural gas, etc.) used in the blast furnaces. Coke serves several purposes: it acts as a heat source for melting ore raw materials, a reducing agent for the ore raw materials, a carburizing agent to lower the melting point of molten iron, and a spacer to ensure ventilation within the blast furnace. Maintaining ventilation with coke stabilizes the loading of the charges and ensures stable operation of the blast furnace. From the perspective of reducing CO2 emissions, it is desirable to have a low proportion of coke charged into the blast furnace. However, if the proportion of coke is reduced, the role that coke plays as described above will also decrease, so it is necessary to improve the permeability along with improving the reduction efficiency of the ore layer. To address this problem, the use of metallic iron raw materials such as reduced iron and iron scrap has been considered, and various proposals have been made regarding their charging methods. Among these, Patent Document 1 describes a method in which reduced iron and iron scrap, held in a secondary hopper at the top of the furnace, are charged together with the ore held in the main hopper via a swirling chute to a section of the furnace where the exhaust gas utilization rate is high, indicating a high reduction load on the ore. The following describes an example using reduced iron as the metallic iron raw material. According to the method described in Patent Document 1, reduced iron can be charged only to areas with a high reduction load in the radial direction of the blast furnace, thereby effectively stabilizing the reduction state of the ore in the furnace and also stabilizing the gas flow. Japanese Patent Publication No. 2019-183270 Shinroku Matsuzaki, Yoshihiro Taguchi, "Analysis of Segregation Phenomena Considering Both Particle Size and Particle Density," Iron and Steel, 2002, Vol. 88, No. 12, pp. 823-830. This is a schematic diagram illustrating the process in one embodiment of the present invention, from cutting the raw materials onto the charging conveyor to transporting them to the top of the blast furnace.This is a schematic diagram illustrating one embodiment of the present invention, in which raw materials are transported to the top of the blast furnace by a charging conveyor and then loaded into the furnace using a raw material charging device.This graph shows the discharge rate of metallic iron raw material (reduced iron) at each stage of raw material discharge from the top bunker in a test in which raw materials were charged into the top bunker according to the conditions of the present invention.An explanatory diagram schematically showing the loading of raw materials through a swirling chute in one embodiment of the present invention.This graph shows an example of the particle size distribution of ore raw materials (sintered ore) at each stage of raw material discharge from the top bunker in a test in which raw materials were charged into the top bunker according to the conditions of the present invention.This diagram schematically illustrates the usage of a segregation control plate installed in a furnace top bunker in another embodiment of the present invention.This is a schematic diagram illustrating the model experimental setup of an actual blast furnace used in an experiment to measure the emission distribution of raw materials (sintered ore and reduced iron) from the top bunker.This is a schematic diagram illustrating the discharge experiment apparatus used in a measurement experiment simulating the distance reduced iron travels within the furnace top bunker.Figure 8 shows the graph of the measurement results for the distance traveled by reduced iron in an experiment using the discharge experimental apparatus.Based on the measurement results of the reduced iron migration distance using the discharge experimental apparatus shown in Figure 8, the graph shows the relationship between the density ratio [ ρHBI ]/[ ρore ] (the ratio of the average apparent density of reduced iron [ ρHBI ] to the average apparent density of sintered ore [ ρore ]) and the representative migration distance.Based on the measurement results of the reduced iron migration distance using the discharge experimental apparatus shown in Figure 8, the graph shows the relationship between the aspect ratio of reduced iron and its representative migration distance.Based on the measurement results of the reduced iron migration distance using the discharge experimental apparatu