Method and system for continuous pre-reduction of solid granular materials
The method and system for pre-reducing solid granular materials using self-reducing furnace gas create a favorable reducing atmosphere for efficient pre-reduction, addressing the underutilization of waste gas reducing power and enhancing energy reuse in iron-making processes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2026-04-02
AI Technical Summary
Existing methods fail to utilize the reducing power of waste gas from self-reducing furnaces for pre-reducing solid granular materials, and there is a need to effectively reuse the remaining calorific value of this gas.
A method and system for continuous pre-reduction of solid granular materials using reducing gas from a self-reducing iron-making furnace, where the gas is injected into a reactor to pre-reduce the material, creating a favorable reducing atmosphere and utilizing the gas's high CO/CO2 ratio and temperature for efficient pre-reduction.
The method achieves efficient pre-reduction of solid granular materials with improved energy efficiency and allows for the reuse of exhaust gas heat for additional processes, enhancing the overall energy utilization in the iron-making process.
Smart Images
Figure 2026510243000001_ABST
Abstract
Description
Field of Invention
[0001]
[0001] The present invention relates to a method for making steel. More specifically, the present invention relates to a method and system for reusing gas from a steelmaking furnace. Background of the Invention
[0002]
[0002] Classical methods for obtaining primary iron from iron oxide are known by the level of the art. Conventionally, blast furnaces have been used as reduction reactors to produce pig iron. In addition, there are direct reduction reactors to produce sponge iron (directly reduced iron - DRI). In these methods, the most common iron raw materials are sintered ore, pellets, and granulated iron ore.
[0003]
[0003] The blast furnace is a shaft reactor operating in countercurrent mode. Sintered ore, pellets, and granular ore are sequentially fed through the top of the furnace along with a reducing agent (coke / coal) and flux (such as limestone) to form an insertion layer of charged iron and reducing agent. Preheated air is introduced into the lower part of the blast furnace through tuyeres located in the upper region of the crucible (combustion zone). Auxiliary fuels, such as pulverized coal injection (PCI), are used along with the blown air. The reaction between the heated air and the carbon in the coke / coal in the combustion zone generates reducing gases, which rise up the reactor and promote the transfer of energy from the hot gases to the charged solids, the reduction of iron ore to metallic iron, and the formation of molten iron, in addition to the formation of the slag phase.
[0004]
[0004] Some more modern furnaces use self-reducing aggregates, which provide much more favorable conditions for reduction. Such equipment is called a self-reducing furnace. Closer contact between iron oxide and carbonaceous material reduces the diffusion pathway of CO to the pellet, resulting in a favorable reaction rate. Thus, the reduction gas generation and oxide reduction reaction described below take place within the aggregate itself. 2MeO (s) +C (s) →2Me (s) +CO 2(g) CO 2(g) +C (s) →2CO (g) MeO (s) + CO (g) → Me (s) + CO 2(g)
[0005]
[0005] In this sense, the aggregate itself efficiently establishes a semi-closed system in which the atmosphere remains reducing throughout the period during which carbon is available therein. Thus, the self-reducing aggregate acts as a mini-reactor.
[0006]
[0006] The exhaust gas from the self-reducing furnace typically has a higher CO / CO2 ratio than the exhaust gas from the blast furnace, and the reducing power increases.
[0007]
[0007] Currently, some industrial methods utilize the gas from the self-reducing furnace to generate electricity through their combustion. However, the use of this reducing power of the gas in metal oxide reduction applications has not been explored.
[0008]
[0008] The present invention solves the problems from the above state of the art in a simple and efficient manner.
Summary of the Invention
[0009]
[0009] A main object of the present invention is to provide a method and a system for the continuous pre-reduction of a solid granular material that utilize the reducing power of the gas from an iron-making self-reducing furnace rich in fuel and reducing gas.
[0010]
[0010] A secondary object of the present invention is to utilize waste gas in other methods, such as afterburning and the reuse of the remaining calorific value.
[0011]
[0011] To achieve the above object, the present invention provides a method for the continuous pre-reduction of a solid granular material, comprising: (i) continuously passing the solid granular material through a reactor; and (ii) pre-reducing the solid granular material by injecting a pre-reducing gas into the reactor when the solid granular material passes through the reactor, wherein the pre-reducing gas comes from an iron-making self-reducing furnace.
[0012]
[0012] The present invention also provides a system for the continuous pre-reduction of solid granular materials. The system comprises a pre-reduction reactor supplied by exhaust gas from a steelmaking self-reduction furnace. The solid granular material passes continuously through the reactor and is pre-reductioned by the pre-reduction gas.
[0013]
[0013] The following detailed descriptions refer to the accompanying drawings and their respective reference numbers. [Brief explanation of the drawing]
[0014] [Figure 1]
[0014] Figure 1 shows a process flowchart according to a preferred embodiment of the present invention. Detailed description of the invention
[0015]
[0015] First of all, the following description should be considered to be based on preferred embodiments of the present invention that will be obvious to those skilled in the art. However, the present invention is not limited to these particular embodiments.
[0016]
[0016] Accordingly, the present invention provides a method for the continuous pre-reduction of a solid granular material 10, the flowchart of which is shown in Figure 1. In the first step, the method of the present invention includes the step of passing the solid granular material 10 continuously through a reactor 20. Preferably, the solid granular material 10 is iron ore. Such a solid granular material 10 may include a wide variety of particle sizes, including fine and ultrafine. Alternatively, the solid granular material 10 is a solid aggregate, such as a self-reducing briquette.
[0017]
[0017] Preferably, the reactor 20 is a rotary cylindrical reactor or any other reactor capable of pre-reducing the solid granular material 10.
[0018]
[0018] In the second step, the method of the present invention includes a step of pre-reducing the solid granular material 10 by injecting a pre-reducing gas 30 into the reactor 20 as the solid granular material 10 passes through the reactor 20. The pre-reducing gas used in the step of pre-reducing the solid granular material 10 comes from a self-reducing ironmaking furnace 40, and the CO / CO2 ratio present in the composition of the exhaust gas from this type of furnace ensures a reducing atmosphere favorable for the pre-reducing of the solid granular material 10. Preferably, the mass ratio of CO / CO2 present in the composition of the gas from the self-reducing ironmaking furnace 40 varies from 1.5 to 3. Thermodynamically, this ratio may be sufficient to achieve a satisfactory degree of metallization.
[0019]
[0019] The gas from the self-reduction furnace 40 has a high CO content in its composition and an exhaust temperature in the range of 600-800°C, which is sufficient for the preliminary reduction of the solid granular material 10. Therefore, the gas from the self-reduction furnace 40 can be injected directly into the reactor 20 without the need for a cooling / heating system. It is worth noting that in blast furnaces, the temperature of the outlet gas can fluctuate between 100-200°C, making it difficult to use them in the preliminary reduction method.
[0020]
[0020] Preferably, the step of passing the solid granular material 10 continuously through the reactor 20 includes moving the solid granular material 10 continuously from a first end of the reactor 20 to a second end of the reactor 20. In this scenario, the first end of the reactor 20 is the inlet end for the solid granular material 10, and the second end of the reactor 20 is the outlet end for the solid granular material 10.
[0021]
[0021] More preferably, the first end of the reactor 20 to which the solid granular material is added is the gas outlet end after pre-reduction. The second end of the reactor 20 is the inlet end for the pre-reduced gas 30 coming from the iron-making self-reduction furnace 40. Therefore, the pre-reduced gas 30 preferably passes through the reactor 20 in countercurrent with the solid granular material 10, promoting heat and mass transfer between the two materials, and thus improving the efficiency of the pre-reduction process. Furthermore, auxiliary fuel may be used to minimize the energy efficiency loss of the top gas throughout the pre-reduction process.
[0022]
[0022] Preferably, after the pre-reduction process of the solid granular material 10 inside the reactor 20, the exhaust gas exiting the pre-reduction system can be used for another purpose, such as reuse by afterburning of its remaining calorific value. The generated heat can be used for a variety of purposes within the iron-making plant.
[0023]
[0023] Preferably, after the pre-reduction process of the solid granular material 10 inside the reactor 20, it is directly directed to the iron-making self-reduction furnace 40 for material reduction.
[0024]
[0024] Alternatively, crushing, separation, and / or magnetic separation techniques can be used, and then the pre-reduced material is subjected to a process of agglomerating it in a reduction furnace for subsequent purposes. This option (i) avoids the generation of agglomerate fines during pre-reduction caused by crystal transitions resulting from phase transitions, and / or (ii) enables a possible low iron concentration in the pre-reduced agglomerates (when the solid granular material is, for example, iron ore or iron agglomerates).
[0025]
[0025] Alternatively, the material can be pre-reduced to a fine / ultrafine particle size and then agglomerated.
[0026]
[0026] The present invention further provides a system relating to the above method, comprising a reactor 20 and a self-reducing ironmaking furnace 40, wherein a solid granular material 10 passes continuously through the inside of the reactor 20 and is pre-reduced by a pre-reducing gas 30 generated from the self-reducing ironmaking furnace 40.
[0027]
[0027] The system according to the present invention further comprises all the conduits necessary for connecting and transporting solid granular material and pre-reducing gas between the reactor 20 and the ironmaking self-reducing furnace 40.
[0028]
[0028] Optionally, a magnetic separation step 50 is provided after the preliminary reduction of the solid granular material 10 and before the transfer of the material to the ironmaking self-reduction furnace 40, with the aim of beneficiating the magnetic material and separating it from gangue from which the magnetic material originates.
[0029]
[0029] Accordingly, as described above, the present invention first provides a method and system for the continuous pre-reduction of solid granular materials, utilizing the reducing power of gas from a self-reduction furnace rich in fuel and reducing gas. As described above, the gas from the self-reduction furnace has a favorable CO2 concentration compared to CO2 and other compounds, ensuring the formation of a reducing atmosphere in the reactor. Furthermore, the gas outlet temperature from the self-reduction furnace meets the criteria for direct injection into the reactor, eliminating the need for a gas heating system.
[0030]
[0030] Several modifications that affect the scope of protection of this application are permitted. Therefore, it is emphasized that the present invention is not limited to the specific configurations / embodiments described above.
Claims
1. A method for continuous pre-reduction of a solid granular material (10), A step of continuously passing a solid granular material (10) through a reactor (20), The process involves pre-reducing the solid granular material (10) by injecting a pre-reducing gas (30) into the reactor (20) as the solid granular material (10) passes through the reactor (20). A method comprising the above, characterized in that the pre-reducing gas (30) comes from a self-reducing furnace (40) for steelmaking.
2. The method according to claim 1, characterized in that the step of continuously passing the solid granular material (10) through the reactor (20) includes continuously moving the solid granular material (10) from a first end of the reactor (20) to a second end of the reactor (20).
3. The method according to claim 2, characterized in that the first end of the reactor (20) is an inlet end for the solid granular material (10) and an outlet end for the pre-reducing gas (30) from the ironmaking self-reducing furnace (40).
4. The method according to claim 2 or 3, characterized in that the second end of the reactor (20) is an outlet end for solid granular material (10) and an inlet end for pre-reducing gas (30) from the ironmaking self-reducing furnace (40).
5. The method according to any one of claims 1 to 4, characterized by including an additional step of post-combustion of the pre-reducing gas (30) to generate heat after the pre-reduction step of the solid granular material (10) inside the reactor (20).
6. The method according to any one of claims 1 to 5, characterized by including an additional step of directing the solid granular material (10), which has been pre-reduced inside the reactor (20), towards the ironmaking self-reduction furnace (40).
7. The method according to any one of claims 1 to 6, characterized in that the reactor (20) is a rotary cylindrical reactor.
8. The method according to any one of claims 1 to 7, characterized by comprising an additional step of grinding the pre-reduced solid granular material (10).
9. An additional step of separating and / or magnetically separating the pulverized material and / or fine and ultrafine ores obtained in the preliminary reduction step, An additional step of agglomerating the separated and / or concentrated material The method according to claim 8, characterized by including the following:
10. A continuous pre-reduction system for a solid granular material (10), Reactor (20), Self-reducing furnace for steelmaking (40) and The reactor (20) is equipped with such a system, and the solid granular material (10) passes through the reactor (20) continuously. A system characterized in that the solid granular material (10) is pre-reduced by a pre-reducing gas (30) generated from the steelmaking self-reducing furnace (40).
11. The system according to claim 10, wherein the reactor (20) comprises a first end and a second end, and the continuous movement of the solid granular material (10) occurs from the first end to the second end.
12. The system according to claim 11, characterized in that the first end of the reactor (20) is an inlet end for a solid granular material (10) and an outlet end for a pre-reducing gas (30) generated from the ironmaking self-reducing furnace (40).
13. The system according to claim 11 or 12, characterized in that the second end of the reactor (20) is an outlet end for solid granular material (10) and an inlet end for pre-reducing gas (30) coming from the ironmaking self-reducing furnace (40).
14. The system according to any one of claims 11 to 13, characterized in that the solid granular material (10) that has been pre-reduced inside the reactor (20) is directed toward the ironmaking self-reduction furnace (40).